the origin and mechanisms of salinization of the lower jordan river the chemical and isotopic 87 sr 86 sr 11 b 34 ssulfate 18 owater 15 nnitrate compositions of water from the lower jordan river and its major tributaries between the sea of galilee and the dead sea were determined in order to reveal the origin of the salinity of the jordan river we identified three separate hydrological zones along the flow of the river 1 a northern section 20 km downstream of its source where the base flow composed of diverted saline and wastewaters is modified due to discharge of shallow sulfate rich groundwater characterized by low 87 sr 86 sr 0 7072 34 ssulfate 2 high 11 b 36 15 nnitrate 15 and high 18 owater 2 to 3 values the shallow groundwater is derived from agricultural drainage water mixed with natural saline groundwater and discharges to both the jordan and yarmouk rivers the contribution of the groundwater component in the jordan river flow deduced from mixing relationships of solutes and strontium isotopes varies from 20 to 50 of the total flow 2 a central zone 20 50 km downstream from its source where salt variations are minimal and the rise of 87 sr 86 sr and so4 cl ratios reflects predominance of eastern surface water flows 3 a southern section 50 100 km downstream of its source where the total dissolved solids of the jordan river increase particularly during the spring 70 80 km and summer 80 100 km to values as high as 11 1 g l variations in the chemical and isotopic compositions of river water along the southern section suggest that the zarqa river 87 sr 86 sr0 70865 11 b25 has a negligible affect on the jordan river instead the river quality is influenced primarily by groundwater discharge composed of sulfate rich saline groundwater cl 31 180 mm so4 cl0 2 0 5 br cl2 310 3 87 sr 86 sr0 70805 11 b30 15 nnitrate 17 34 ssulfate4 10 and ca chloride rift valley brines cl 846 1500 mm br cl 6 8 10 3 87 sr 86 sr0 7080 11 b40 34 ssulfate4 10 mixing calculations indicate that the groundwater discharged to the river is composed of varying proportions of brines and sulfate rich saline groundwater solute mass balance calculations point to a 10 contribution of saline groundwater cl282 to 564 mm to the river a high nitrate level up to 2 5 mm in the groundwater suggests that drainage of wastewater derived irrigation water is an important source for the groundwater this irrigation water appears to leach pleistocene sediments of the jordan valley resulting in elevated sulfate contents and altered strontium and boron isotopic compo sitions of the groundwater that in turn impacts the water quality of the lower jordan river copyright 2004 elsevier ltd

carbonate platform evolution from a bioconstructed platform margin to a sand shoal system devonian guilin south china the depositional organization and architecture of the middle late devonian yangdi rimmed carbonate platform margin in the guilin area of south china were related to oblique extensional faulting in a strike slip setting the platform margin shows two main stages of construction in the late givetian to frasnian with a bioconstructed margin evolving into a sand shoal system in the late givetian the platform margin was rimmed with microbial buildups composed mainly of cyanobacterial colonies mostly renalcis and epiphyton these grew upwards and produced an aggradational locally slightly retrogradational architecture with steep foreslope clinoforms three depositional sequences s3 s5 are recognized in the upper givetian strata which are dominated by extensive microbialites metre scale depositional cyclicity occurs in most facies associations except in the platform margin buildups and upper foreslope facies in the latest givetian at the top of sequence s5 relative platform uplift subaerial exposure and associated rapid basin subsidence probably a block tilting effect caused large scale platform collapse and slope erosion to give local scalloped embayments along the platform margin and the synchronous demise of microbial buildups subsequently sand shoals and banks composed of ooids and peloids and a little later stromatoporoid buildups on the palaeohighs developed along the platform margin from which abundant loose sediment was transported downslope to form gravity flow deposits another strong tectonic episode caused further platform collapse in the early frasnian at the top of sequence s6 leading to large scale breccia release and the death of the stromatoporoid buildups siliceous facies banded cherts and siliceous shales were then deposited extensively in the basin centre as a result of the influx of hydrothermal fluids the platform margin sand shoal bank system possibly with gullies on the slope persisted into the latest frasnian until the restoration of microbial buildups four sequences s6 s9 characterized by abundant sand shoal deposits on the margin and gravity flow and hemipelagic deposits on the slope are distinguished in the frasnian strata smaller scale depositional cyclicity is evident in all facies associations across the platform slope basin transect the distinctive depositional architecture and evolution of this yangdi platform are interpreted as having been controlled mainly by regional tectonics with contributions from eustasy environmental factors oceanographic setting biotic and sedimentary fabrics

evidence for extended hercynian basement and a preserved jurassic basin margin tract in northern calabria southern italy the longobucco basin abstract in the longobucco basin northeastern calabria southern italy a mesozoic succession covers the hercynian basement documenting the evolution of a continental margin during the early jurassic extensional tectonic phase correlated with the western tethys rift the basin evolved from continental red beds around the rhaetian hettangian boundary to shallow marine and eventually deep sea siliciclastic turbidites in the late pliensbachian toarcian to dominantly pelagic deposits middle jurassic onwards around the sinemurian pliensbachian boundary following a prominent phase of normal faulting sedimentation took different paths in either hangingwall block or footwall block settings this study based on geological mapping focuses on the southwestern boundary of the longobucco basin and in particular on the mutual relationships existing between the deeper water basin fill units fiume trionto and fosso petrone formations the basement and the shallow water limestone of the caloveto formation which forms a narrow strip running parallel to the rift shoulder the contacts among the above mentioned units are generally all stratigraphic unconformities of various types onlap downlap nonconformity these characteristics separate the study area from the depocentral parts of the basin in terms of vertical stratigraphy nature of contacts among stratigraphic units unconformable vs conformable and impact of synsedimentary tectonics the signature of early jurassic extension occurs in the form of 1 laterally continuous clastic bodies interpreted as products of catastrophic basin margin collapse and avalanching 2 exhumation of the pre rift units which are otherwise deeply buried and 3 neptunian dykes of at least two generations our new data provide evidence for the presence of a 20 km long nw se trending preserved paleoescarpment where the basinal units onlap either the basement or the caloveto formation which forms a fringing carbonate body with intriguing facies and bio sedimentological features the paleoescarpment was the submarine morphological expression of a sinemurian pliensbachian fault as testified by the age of the clastic body that seals it another pulse of synsedimentary extension took place in the latest pliensbachian toarcian overprinting the existing rift architecture and reviving the production of megaclastic deposits

dolomitization of miocene carbonates gulf of suez egypt abstract miocene reef and platform carbonates exposed along the red sea coast at gebel abu shaar and west gemsa are entirely dolostone while exhibiting all the textures and fabrics of a metastable suite of carbonate sediments that has undergone meteoric diagenesis the microfabrics of former mg calcite fibrous marine cements and bioclasts and calcite particles are well preserved and commonly mimetically replaced originally aragonitic components typically illustrate little to no microfabric retention or are leached yielding moldic to vuggy porosity dolomite cement and replacement crystals have inclusion rich or dissolved cores and relatively inclusion free rims most crystals are anhedral and many have an irregular microtopography generated by leaching of crystal surfaces carbon and oxygen isotope values vary widely many samples have the low positive values characteristic of marine precipitates but others are depleted in 13c and 180 reaching minimum 13c and 18o values of 8 9 and 8 0 0 pdb respectively the origin of these dolostones can be explained by two hypotheses the first is dolomitization of a partially stabilized or unaltered mg calcite and aragonite sediment in a zone of mixed freshwater and seawater following dolomite formation the progressive lowering of sea level and resultant freshening of the mixing zone caused leaching of dolomite crystal cores and corrosion of crystal faces the second hypothesis invokes two dolomitization events an earlier pervasive dolomitization by marine or hypersaline waters followed by recrystallization in meteoric or hydrothermal fluids and then selective dissolution both hypotheses are consistent with the geologic setting of these sediments but the pervasive nature of the dolostone favors the recrystallization hypothesis vadose calcite cement ferric oxide hydroxide crusts and secondary evaporite cement are the latest precipitates although they occlude only a minor amount of primary and secondary porosity

patterns of accretion of reefs in the sudanese red sea abstract reefs in the north towartit and shambaya groups of the sudanese red sea rest on major blocks which have been defined by large scale fault movements the dominant surface features in these areas have been formed by the sub aerial sculpting of tertiary and later limestones during late pleistocene periods of low sea level stand this has resulted in the formation of large numbers of closed depressions reaching 30 m depth these punctuate a surface lying between 20 and 30 m which is itself probably a residual of an older undulating higher level surface the margins of depressions are submarine cliffs the smooth floors are blanketted with recent sediments while the intervening ridges have become the sites for reef accretion present coral growth began about 6000 years ago and has reached a thickness of 10 to 20 m it has been limited in deeper water but in shallower areas may have been aided by establishment on existing pinnacles steep margins occur on both the windward baraja and leeward towartit harvey margins of reefs these may result from inequalities of growth but cannot be directly related to environmental energy windward and leeward shores are characterised by contrasted coral associations a windward acropora association and a leeward porites association this distribution reflects a depletion of resources downcurrent rather than major differences in water movement reef edges are the most important sediment generating zones and patterns of dispersal point to a dominant westward downwind movement 50 80 of sediments coarser than 1 o are coral and algal fragments mollusc shells are a minor component but reach 26 on the towartit fringe homotrema benthic forams bryozoa crustacean and echinoderm fragments rarely rise above a few percent each mean sizes of sediments range from 2 3167 to 1 2333 o with the coarsest close to the reef edges and the finest in deep water or down current most are poorly sorted and values for standard deviation range between 2 1714 and 0 9512 o skewness values indicate symmetrical or coarse skewed distributions 0 0132 to 0 4982 finally figures for normalised kurtosis range between 0 6023 and 0 4532 these suggest that sediments consist of at least two sub populations 1 a base stock generated in the edge zone with characteristics varying systematically down current and 2 grains formed within the transport system with characters owing more to ecological factors than hydrodynamics the irregular mixing of these two accounts for the variation shown in conclusion the character of the reefs depends both upon present day processes and an inherited morphology

stratal architecture and platform evolution of an early frasnian syn tectonic carbonate platform canning basin australia facies architecture and platform evolution of an early frasnian reef complex in the northern canning basin of north western australia were strongly controlled by syn depositional faulting during a phase of basin extension the margin attached hull platform developed on a fault block of precambrian basement with accommodation largely generated by movement along the mount elma fault zone recognition of major subaerial exposure and flooding surfaces in the hull platform from outcrop and drillcore has enabled comparison of facies associations within a temporal framework and led to identification of three stages of platform evolution stage 1 records initial ramp development on the hangingwall dip slope with predominantly deep subtidal conditions that prevented any cyclic facies arrangements this stage is characterised by basal siliciclastic deposits and a major deepening upward facies pattern that is capped by a sequence boundary towards the footwall north west and a major flooding surface towards the hangingwall stage 2 reflects the bulk of platform aggradation significant platform growth towards the hangingwall and the development of reef margins and cyclic facies arrangements thickening of this stage towards the hangingwall indicates that accommodation was generated by rotation of the fault block and overlying platform stage 3 records a major flooding and backstep of the platform margin the hull platform illustrates important elements of margin attached carbonate platforms in a half graben setting including i prominent but limited coarse siliciclastic input that does not have a major detrimental effect on carbonate production near the rift margin in arid to semi arid settings ii wedge shaped accommodation created by syn depositional rotation of fault blocks and tilting of the hangingwall dip slope resulting in shallow water facies and subaerial exposure up dip of the rotational axis and deeper water facies down dip and iii evolution of a ramp to rimmed shelf coincident with a sequence boundary flooding surface that is accelerated by tilting of the hangingwall dip slope during fault block rotation

the paradox of drowned reefs and carbonate platforms shallow water carbonate platforms and reefs are drowned when tectonic subsidence or rising sea level outpaces carbonate accumulation and benthonic carbonate production ceases drowned platforms are common in the geologic record but they present a paradox if one considers rates of processes involved during the early holocene when sea level rose at rates of 6 000 to 10 000 m yr mm 1 000 yr most reefs and platforms were outpaced by the rising sea during the late holocene with sea level rising 500 to 3 000 m yr in the atlantic caribbean area reefs and platforms started to recover built to sea level and prograded seaward 1 000 m yr is thus a conservative estimate of the average growth potential of modern reefs and platforms independently accumulation rates of prograding platforms in the geologic record suggest growth potential in excess of several hundred microns per year the growth potential of 1 000 m yr exceeds any relative rise of sea level caused by long term processes in the geologic record newly formed ocean crust subsides at a maximum of 250 m yr basin subsidence averages 10 to 100 m yr and sea level rises due to increased sea floor spreading amount to less than 10 m yr rapid pulses of relative rise of sea level or reduction of benthic growth by deterioration of the environment remain the only plausible explanations of drowning the geologic record shows examples of both of these processes global mass extinctions of reefs and platforms occurred in the middle cretaceous eustatic rise due to submarine volcanism or desiccation of a small ocean basin and the late devonian global crisis of ocean environment extraterrestrial cause drowning controlled by regional tectonics prevailed in the jurassic and early cretaceous of the tethyan realm and the drowning of mesozoic platforms in the western north atlantic seems to have been dictated by plate tectonic drift to higher latitudes

tracing tectonic deformation using the sedimentary record an overview tectonic activity on a range of scales is a fundamental control on sedimentary activity the range of structural deformation within a region extends from the plate tectonic scale governing for example rift initiation to the basin scale with the formation of basin bounding faults internal basin configuration is also strongly influenced by tectonic activity however the relationship between tectonic activity and sedimentation is a complex one given the many additional factors which can also influence sedimentary activity including erosion sediment transport source area lithology groundwater chemistry range of depositional environments climate eustasy and the relative location of an area and its distality to marine influences in this paper we provide a selective overview of the issues associated with the interlinked themes of tectonics and sedimentation examining the main basin types forming in both extensional and compressional plate settings we then review the various models of sedimentation in the selected basins both on a local and a basinal scale finally we look to the future providing a series of possible research areas almost exclusively multidisciplinary which would help to improve existing models of interlinked sediment tectonics systems

hydrogeochemical characteristics of surface water and groundwater in the karst basin southwest china groundwater is a very significant water source used for irrigation and drinking purposes in the karst region and therefore understanding the hydrogeochemistry of karst water is extremely important surface water and groundwater were collected and major chemical compositions and environmental isotopes in the water were measured in order to reveal the geochemical processes affecting water quality in the gaoping karst basin southwest china dominated by ca 2 mg 2 hco 3 and so 4 2 the groundwater is typically characterized by ca mg hco 3 type in a shallow aquifer and ca mg so 4 type in a deeper aquifer dissolution of dolomite aquifer with gypsiferous rocks and dedolomitization in karst aquifers are important processes for chemical compositions of water in the study basin and produce water with increased mg 2 ca 2 and so 4 2 concentrations and also increased tds in surface water and groundwater mg 2 ca 2 molar ratios in groundwater decrease slightly due to dedolomitization while the mixing of discharge of groundwater with high mg 2 ca 2 ratios may be responsible for mg 2 ca 2 ratios obviously increasing in surface water and mg 2 ca 2 ratios in both surface water and groundwater finally tending to a constant in combination with environmental isotopic analyses the major mechanism responsible for the water chemistry and its geochemical evolution in the study basin can be revealed as being mainly from the water rock interaction in karst aquifers the agricultural irrigation and its infiltration the mixing of surface water and groundwater and the water movement along faults and joints in the karst basin

the chemical evolution of kurnub group paleowater in the sinai negev province a mass balance approach abstract the chemical evolution of the kurnub group paleowater was studied starting from rainwater in recharge areas of the sinai and along groundwater flowpaths leading to the natural outlets of this regional aquifer this was achieved by investigating the chemical composition of groundwater ionic ratios degrees of saturation with common mineral species normative analysis of dissolved salts and by modeling of rock water interaction and mixing processes occurring along groundwater flow paths the initial groundwater composition used is from the nakhel well in sinai it evolves from desert rainwater percolating through typical kurnub group lithology in sinai this rainwater dissolves mainly gypsum halite and dolomite together with smaller amounts of marine aerosol and k feldspar at the same time it precipitates calcite sio 2 smectite and degasses co 2 between the area of nakhel and the northern negev the chemistry of kurnub group waters is influenced by dissolution of halite and lesser amounts of gypsum of surficial origin in recharge areas small amounts of feldspars and of dolomite cement in sandstones eroded from the arabo nubian igneous massif of sinai and organic degradation derived co 2 concomitantly there is precipitation of calcite smectite sio 2 and probably analcime characteristic of sediments in continental closed basins north of the negev the kurnub group fluids are diluted and altered by mixing with judea group aquifer groundwaters on the e there is mixing with residual brines from the water body ancestral to the dead sea prior to discharge into the arava valley rock water interaction indicated by netpath and phreeqc modeling is in agreement with lithology and facies changes previously observed in the kurnub group sequence

aeolian microtextures in silica spheres induced in a wind tunnel experiment comparison with aeolian quartz abstract microtextures in quartz attributed to aeolian transport principally bulbous edges and abrasion fatigue have seldom been tested in the laboratory under controlled conditions a wind tunnel experiment was conducted using glass spheres 70 sio 2 as a proxy for quartz with the objective of determining the extent of mechanical damage to silica glass transported in a mixture with quartz beach sand the microspheres were microscopically imaged prior to transport in a wind tunnel subjected at velocities ranging from 4 to 13 m s in sequential runs of 10 min the range in velocity is capable of lifting grains into the air column or saltating quartz grains and silica glass spheres to produce mechanical impact i e abrasion commonly experienced in aeolian transport with increasing velocity silica glass spheres which displayed minor imperfections prior to transport began to show significant grain damage exhibiting increasing depth into the silica glass fabric a result of mechanical contact as well as increasing frequency of craters dislodged plates and abrasion fatigue while pits appear earlier in the experiment 8 m s dislodged plates and abrasion fatigue need a threshold velocity of near 10 m s to become more frequent bulbous edges on the grain surface often considered the hallmark of aeolian transport are not seen in the grain population analyzed possibly because of the initial near perfect sphericity of the silica glass spheres the experiment proved that aeolian transport throughout short distances and during a relatively short period of time is enough to imprint significant abrasion marks in microspheres in fact the microtextures produced were fresh surfaces fractures and abrasion that imprinted areas of different sizes a comparison of microtextural imprints on silica glass spheres relative to coastal dune sands was made to better understand energy thresholds required to achieve grain damage

environmental isotope study of the major karst springs in damascus limestone aquifer systems case of the figeh and barada springs abstract the groundwaters of major karst springs and several piezometers and wells in the damascus limestone aquifer systems syria have been investigated using chemical and environmental isotope techniques the groundwater bodies of major karst springs mainly originate from direct infiltration of atmospheric water the groundwaters emerging from the figeh main spring have lower stable isotope concentrations than those emerging from the barada spring stable isotopes show that the elevation of the recharge zones of the figeh main spring 1750 m above sea level is higher than those for the figeh side spring 1500 m and the harouch spring 1300 m the groundwater in the barada spring seems to be recharged in a catchment area with a mean elevation of about 1250 m the temporal evolution of stable isotope concentrations tritium content and hydrochemistry show the existence of an interconnection between the aquifers of the figeh main spring and the figeh side spring especially during flood periods the distinct independent isotopic composition of harouch spring from those of figeh main and side springs suggests no interconnection with the figeh aquifers adopting a model with exponential time distribution the mean turnover time residence time of groundwater in figeh main spring was evaluated to be 50 years on the basis of this evaluation a value of about 3 9 billion m 3 was obtained for the maximum groundwater reservoir size 1997 elsevier science b v

facies and geologic history of an exposed miocene rift margin carbonate platform gulf of suez egypt abu shaar is a small exhumed carbonate platform of lower to middle miocene age on a horst of precambrian crystalline rock along the western side of the gulf of suez the reef rimmed complex is entirely dolomite but with exquisitely preserved primary and diagenetic microfabrics similar platforms some of which contain hydrocarbons are buried beneath evaporites in the gulf the platform developed in three stages defined as local members of the rudeis formation the first stage records deposition during progressive marine onlap as aprons of mixed terrigenous carbonate sediments evolved into a wide reef rimmed platform synsedimentary platform margin collapse subsequently removed the most seaward portions of the reefs along the eastern gulf facing margin these truncation surfaces were then covered by a second phase of reef growth and deposition of fore reef carbonates the third and final stage deposited following a sea level drop and subaerial exposure is a series of well bedded peritidal carbonates that become progressively more evaporitic upward fore reef facies are again truncated by synsedimentary slope failure former evaporites are now recorded as collapse breccias contorted bedding black chert nodules and evaporite molds porosity is mainly secondary as vugs and molds and is highest in platform interior facies these more porous sediments contained more aragonitic components originally and were less affected by submarine cementation in contrast the higher degree of synsedimentary lithification of platform margin reef and fore reef sediments is comparable with what is commonly observed in modern reef dominated platform margins

early permian deep water allochthonous limestone facies and reservoir west texas conventional cores from six wells in southwest reagan and northern crockett counties texas recovered interbedded limestone conglomerate intraclast and bioclast limestone calcarenite and shale twenty one lithologies are grouped into six lithofacies based on study of slabbed core surfaces lithoclast rudstone floatstone porous bioclast lithoclast rudstone floatstone bioclast wackestone intraclast floatstone rudstone thin bedded grainstone packstone calcarenite and dark gray shale the limestone facies are interpreted on the basis of petrologic characteristics biota regional stratigraphic setting and facies stratigraphy as deep water and allochthonous biotic constituents within the lithoclasts and matrix indicate an early permian wolfcamp age the porous bioclast lithoclast rudstone floatstone facies contains a modest but geologically significant oil reservoir at gunnx field southwest reagan county production is from 10 ft 3 m of perforations in about 42 ft 13 m of pale yellow brown porous limestone with intercrystalline reduced and solution enlarged biomoldic intraskeletal fracture and possible intergranular porosity moldic porosity appears to be mainly within lithoclasts baroque dolomite is rare to common and partly to completely fills former void space in addition to calcite spar and micrite porosity generally ranges 7 18 the producing depth is about 9 450 ft 2 880 m and the trap is stratigraphic the cored sequence at gunnx is interpreted as a basin floor complex of debris flow sheets which contain the reservoir overlain by interbedded thin carbonate turbidites thin debris flow sheets and shale the lowermost debris flow at gunnx was deposited on a thin generally undated shale the lower part of which is late pennsylvanian at west world field the shale is interpreted as representing starved basin floor deposition and abruptly overlies shallow water strawn limestone in core at west world field carbonate detrital components in the limestone at gunnx were probably derived from a wolfcamp platform at least 10 mi 16 km west and were emplaced by various submarine gravity flow processes age and facies determinations from cores in the gunnx area significantly alter earlier stratigraphic interpretations made with wireline logs alone late paleozoic allochthonous carbonate facies may provide significant new reserves in the permian basin

tertiary syntectonic carbonate platform development in indonesia cenozoic tropical carbonate sedimentation was strongly influenced by local and regional tectonics in se asia this paper outlines the evolution of the syntectonic eocene to middle miocene tonasa formation of south sulawesi evaluating controls on sedimentation facies distribution and sequence development development of a facies model for this cenozoic tropical carbonate platform provides a meaningful analogue for similar less well studied se asian carbonates which commonly comprise targets for hydrocarbon exploration this study also has considerable implications for the study of syntectonic carbonates controls on carbonate sedimentation carbonate platform development in backarc areas and se asian tectonics detailed facies mapping logging petrographic and biostratigraphic analyses indicate that the tonasa formation was deposited initially as part of a transgressive sequence in a backarc setting by late eocene times shallow water carbonates were being deposited over much of south sulawesi forming a widespread 100 km long platform area shallow water sedimentation continued unabated in some areas of the platform until the middle miocene elsewhere active normal faulting resulted in fault block platforms with local subaerial exposure of footwall blocks and the formation of basinal graben in adjacent hangingwall areas platform top facies were aggradational and dominated by larger benthic foraminifera low angle slopes particularly hangingwall dip slopes were characterized by the development of ramps faults controlled in part by pre existing structures were periodically active and formed steep escarpment margins variable regional subsidence strongly influenced the development of the tonasa carbonate platform whereas platform wide effects caused by regional eustacy have not been identified computer modelling of the tonasa platform confirms that the accommodation space and sedimentary geometries observed can be produced by block faulting and regional subsidence alone modelling also reveals that regional subsidence and extension oblique to the main stretching direction were low on the margins of the backarc basin shallow water accumulation rates for this foraminifera dominated tropical carbonate platform were an order of magnitude lower than those for modern warm water platforms dominated by corals or ooids

the geochemistry of groundwater resources in the jordan valley the impact of the rift valley brines the chemical composition of groundwater in the jordan valley along the section between the sea of galilee and the dead sea is investigated in order to evaluate the origin of the groundwater resources and in particular to elucidate the role of deep brines on the chemical composition of the regional groundwater resources in the jordan valley samples were collected from shallow groundwater in research boreholes on two sites in the northern and southern parts of the jordan valley adjacent to the jordan river data is also compiled from previous published studies geochemical data e g br cl na cl and so4 cl ratios and b o sr and s isotopic compositions are used to define groundwater groups to map their distribution in the jordan valley and to evaluate their origin the combined geochemical tools enabled the delineation of three major sources of solutes that differentially affect the quality of groundwater in the jordan valley 1 flow and mixing with hypersaline brines with high br cl 2 10 3 and low na cl 0 8 ratios 2 dissolution of highly soluble salts e g halite gypsum in the host sediments resulting in typically lower br cl signal 2 10 3 and 3 recharge of anthropogenic effluents primarily derived from evaporated agricultural return flow that has interacted e g base exchange reactions with the overlying soil it is shown that shallow saline groundwaters influenced by brine mixing exhibit a north south variation in their br cl and na cl ratios this chemical trend was observed also in hypersaline brines in the jordan valley which suggests a local mixing process between the water bodies

listric normal faults an illustrated summary movement along listric normal faults is instrumental in formation of several types of structural traps e g rollover anticlines and upthrown fault block closures this type of fault may occur where brittle rocks overlie ductile rocks in an extensional regime the extensional regime may be locally derived within a broader stress regime of another type as evidenced by transtension associated with strike slip movement and arched strata in a compressive setting the flattening of the fault reflects an increase in ductility of the rocks with depth and in some cases deformation of the fault due to compaction or tilting of the upthrown block the dip angle may vary along the strike of the fault in response to changes in throw in cross section a listric fault may consist of relatively short en echelon fault segments this geometry may be particularly characteristic of growth faults sedimentary faults may sole in ductile strata or they may represent the brittle part of a fault flow system fault patterns commonly are characterized by bifurcation some of which may occur near the ends of individual faults comprising a zone although unequivocal recognition of listric normal faults requires unusually extensive outcrop data close subsurface control or high quality seismic data their presence is suggested indirectly by such features as increasing dip either depth toward the controlling fault reverse drag thick progradational sandstone overlying ductile strata and in some cases arcuate fault patterns basins or uplifts listric normal faults form during rifting drifting and evolution of passive continental margins with concomitant basinal development the basement is offset by listric faults as a fundamental element in the development of other types of basins including those which formed during postorogenic extension they also occur as secondary extensional features in an overall compressive stress regime due to plate convergence and during transform or strike slip faulting modified journal abstract

tectonic control on carbonate platform facies distribution and sequence development miocene gulf of suez abstract mid miocene deposition in the southwestern gulf of suez was governed by an extensional fault block topography shallow marine carbonates and clastics were deposited around the exposed block crests and in marginal half grabens of the rift while central troughs were filled by slope aprons and turbiditic and pelagic mudstones fan deltas developed at points along the fault block escarpments syn rift platform carbonates from one block crest esh el mellaha are described here the platform evolved in three stages generating three sedimentary sequences sequences 1 and 2 were separated by boundary fault reactivation sequences 2 and 3 by sea level drawdown exposure and karstification the sediments comprise six lithofacies associations la 1 6 reef la 1 fore reef la 2 and back reef embayment la 3 sediments form a small reef rimmed platform in sequence 1 at the southern end of the block fringing reefs and reef lagoon systems also developed along the footwall escarpment and on fan deltas which bridged the block bounding fault fringing reefs in sequence 2 generated a carbonate talus veneer la 4 along the whole 80 km length of the esh el mellaha fault scarp carbonate slope and reefal sediments preserved on the footwall exhibit abundant evidence of syndepositional fault movements with truncation of escarpment fringing sequences and repeated generation of reefal wedges minor drowning at the sequence 1 2 boundary caused deepening of lagoons progradation of leeward reefal margins with lagoonal patch reef development and back stepping and vertical accretion of the reefal rim platform development was followed by algal laminated dolomitic sediments la 5 in the area of the old platform interior sequence 3 much of the esh el mellaha ridge remained exposed during platform growth and shed coarse alluvial clastic sediments la 6 into the peripheral marine environments the relationships demonstrated between miocene sedimentation and structural setting have parallels in the modern environments of the zeit bay area

hydrochemical processes in the lower jordan valley and in the dead sea area abstract changes in the concentrations of major some minor and trace elements occurring in both surface and groundwater of the lower jordan river dead sea drainage basin have been investigated in order to identify the characteristics of the regional aquifers and their recharge areas spider patterns of elements and rare earth distribution patterns pinpoint the characteristic chemical features of groundwater as compared to seawater the high br cl ratios in groundwater are caused either by high br cl ratios in precipitation by leaching of br from bituminous matter or by mixing with brines beyond the epsomite stage the locations of groundwater samples with enhanced b contents coincide with the distribution of gypsum in the beds of the lisan formation which produces water with nearly constant b so 4 2 molar ratios aeolian distribution of the unconsolidated lisan sediments influences the b so 4 ratio in the area of lake tiberias and in the jordan highlands the high gd anomaly in the dead sea water is of geologic origin whereas that in the jordan river and in nahal stream qidron is largely anthropogenic the anthropogenic gd input to the dead sea is insignificant compared to the actual amount in the water of the dead sea hot saline water encountered along the western shores of the dead sea with high gd anomalies indicate that they contain large amounts of ancient dead sea water that mix as hot ascending brines with fresh water the recharge area of groundwater in the lower jordan valley extends largely over limestone and dolomite outcrops of the upper cretaceous judea group weathering of locally underlying lower cretaceous volcanics in the area of pezael beqaot and argaman yield groundwater with 34 s so 4 2 values ranging from 2 to 4 the presence of sulphide bearing bodies in this area is attested to magnetic anomalies detected at depths of several kilometres 34 s so 4 2 indicates very deep groundwater circulation high 34 s so 4 2 15 is typical for marine sulphates from the judea and avedat group limestone the springs located along the northwestern shore of the dead sea discharge water replenished on the eastern judea mountains the increase in the salinity of this water is due to brines flushed from sediments and from adjacent sedimentary rocks which host entrapped brines from the precursors of the dead sea formed during the late stages of lake lisan fresher water flushes out these residual brines as a result of falling sea level salinity increase in groundwater is also affected by the ascent of deep seated hot brines from pre sedom periods along the rift faults calculations of mixing between fresh and highly saline end members show that leaching of anhydrite from sediments precipitation of calcite formation of dolomite albitization of plagioclase and ion exchange with abundant clay minerals control the major element composition of the saline groundwater

surface textures of heavy mineral grains a new contribution to provenance studies abstract the study zone is geologically very complex and corresponds to the western limits of the betic cordilleras sw spain materials from the triassic to holocene are found here this study demonstrates that most of the surface textures seen on quartz are present on the seven selected heavy minerals sem analysis of heavy mineral grains reveals that certain morphologies are in part associated with particular surface textures this textural analysis enables the source areas to be differentiated more clearly equally it contributes to a deeper knowledge of the various stages of the grains provenance a good example is the study of the heavy minerals of the guadalete river terraces

ca chloride brines at common outlets of the bet shean harod multiple aquifer system israel abstract the bet shean and harod valleys are regional recipients and mixing zones for groundwaters draining into them from a multiple aquifer system which includes carbonate and basalt aquifers and deep seated reservoirs of brine the outlets of the three aquifers are located at the mountain border separating the valleys from the gilboa and ramot issakhar mts the aquifers drain through two types of outlets unique and common the latter type is mainly conditioned by the occurrence of fault blocks acting as connecting media between the aquifers upon reaching the interconnecting zones fresh groundwater flowing from carbonate and basalt aquifers intermix losing their hydrochemical identities ca chloride brines originating from deep seated and confined reservoirs leak along the deep seated faults characterizing the common outlet zones and contaminate the relatively fresh mixing products originating from the three regional aquifers two types of dilute ca chloride brines were identified in the study area the devora type is a hot and hypersaline source brine which was identified at great depth and under very high hydrostatic pressures this brine could be the residual product of seawater that evaporated during the cambrian cretaceous continental interval and subsequent prolonged interaction with surrounding carbonate rocks the neve ur type brine seems to be genetically related to the neogene inland sdom sea that preceeded the contemporary dead sea

characterization of surface water and groundwater in the damascus ghotta basin hydrochemical and environmental isotopes approaches the hydrochemistry of major ions and environmental isotope compositions 18o 2h and tritium of water samples have been used to investigate the characteristics of rainfalls surface water and groundwater in the damascus ghotta basin the groundwater salinity in the damascus ghotta basin gradually increases as the groundwater moves from western to south eastern and north eastern parts of the basin a strong relationship exists between the barada river and the surrounded groundwaters mainly in terms of recharge by infiltration of surface waters the groundwater quality in the adra region has clearly become less saline as a result of establishment of the sewage water treatment station in this area since 1997 the uncommon depleted stable isotope concentrations in the vicinity of al ateibeh lake and adra valley could be interpreted as a result of sub flow recharge from the cenomanian turonian aquifer mostly prolonged along the damascus fault which forms direct contact between this complex and the quaternary alluvium aquifers the extensive exploitation of water from the cenomanian turonian aquifer for drinking water supply would shortly be reflected by a gradual decline of the groundwater table in the damascus ghotta basin amelioration of water quality in the damascus basin still requires further management strategies and efforts to be taken within the forthcoming years

acidification of shallow groundwater in the unconfined sandy aquifer of the city of douala cameroon western africa implications for groundwater quality and use the alluvial aquifer underlying the city of douala comprises shallow quaternary deposits where groundwater is the main source for domestic and drinking purposes shallow groundwater in the area show signs of acidification with average ph range of 3 8 6 8 long term groundwater chemistry data 1998 2013 hydrogeochemical and r mode factor analysis were used to establish the acidification process of shallow groundwater and also determine possible origin and implications for water quality and use in the area twenty six groundwater sample points three streams and three rain sample points were studied seasonally in the 2006 2008 and the 2010 2013 study periods the data were compared with result of a study 7 years earlier 1998 1999 the results show evidence of acidification manifested by depletion of hco3 a decrease in the ph and increase in so4 and no3 concentrations of shallow groundwater average groundwater ph range is 3 94 7 70 1998 1999 3 8 6 91 2006 2008 and 3 7 6 8 2010 2013 only approximately 16 1998 1999 14 2006 2008 and 11 11 2010 2013 of water samples fall within the range of ph 6 5 8 5 for potable water according to who 1993 the alkalinity acid neutralizing capacity of the shallow groundwater has decreased significantly coupled with increase in the number of zero alkalinities recorded in the 2010 2013 the shallow groundwater is generally undersaturated with common carbonate minerals calcite dolomite therefore providing insufficient acid buffer principal component analysis in combination with hydrogeochemical studies revealed that four main factors are responsible for the groundwater chemistry and acidity 1 acid atmospheric deposition 2 anthropogenic activities industrial effluent discharges and acid spill 3 chemical weathering and 4 coastal atmospheric deposition cation exchange in general the shallow groundwater is not suitable for drinking and domestic purposes with respect to the low ph and elevated nitrate concentration in view of the implications such as increase in corrosion and increased mobilization of toxic elements e g al pb cu zn mn as well as their possible harmful effect on health it is recommended that the causes rate of acidification and the mobility of trace elements be investigated with more details

evaporitic subtidal stromatolites produced by in situ precipitation textures facies associations and temporal significance abstract the transition between carbonate platforms or isolated carbonate buildups and overlying evaporites commonly is marked by assemblages of stromatolites and interlaminated carbonates and evaporites stromatolites display lamination textures that vary from peloidal and discontinuous on a scale of a millimeter to a few centimeters to isopachous and continuously laminated on a scale of a centimeter to a few meters the isopachous lamination texture may be composed of either 1 micritic or radial fibrous calcite or 2 dolomite isopachous stromatolitic laminae are remarkably uniform varying little in thickness over a given lateral distance in contrast to stromatolites formed of peloidal laminae which show marked variation in thickness over an equivalent lateral distance these isopachous textures are uncommon on most open marine carbonate platforms and apparently developed in transitional carbonate to evaporite settings because of increasing temperature salinity and anoxia related to water stratification which would have created ecologic restriction and an opportunity for stromatolite growth stromatolites with isopachous lamination are here interpreted to have formed as a result of in situ precipitation of sea floor encrusting calcite and possibly dolomite whereas the stromatolites composed of peloidal discontinuous lamination are inferred to have formed by trapping and binding of loose carbonate sediment in microbial mats while the presence of microbes in almost all near surface environments nullifies use of the term abiotic to describe most precipitated minerals we interpret growth of the isopachous stromatolites to have been dominated by chemogenic precipitation in the absence of microbial mats and the growth of peloidal stromatolites to have been controlled by sedimentation in the presence of microbial mats these transitional stromatolite facies are best developed atop proterozoic and paleozoic carbonate platforms that underlie major evaporite successions however inspection of jurassic and younger evaporite basins such as the messinian of the mediterranean region shows that stromatolites with thin isopachous lamination and radial fibrous textures though present are rare instead these facies may have been replaced by stromatolites with peloidal clastic textures and by low diversity diatomaceous and coccolith mudstones accumulation of the mudstones would have imposed two important effects 1 production of coccoliths would have helped extract calcium carbonate from seawater thus lowering the growth potential for precipitation of sea floor encrusting stromatolites 2 settling of both coccoliths and diatoms would have created a sediment flux to the sea floor which would have served to impede growth of precipitated stromatolites because of smothering of growing crystals

sedimentation during carbonate ramp to slope evolution in a tectonically active area bowland basin dinantian northern england the bowland basin northern england contains a series of carbonates and terrigenous mudstones deposited during the ivorian to early brigantian two regional depositional environments are indicated by facies and facies associations wackestone packstone and calcarenite facies indicate deposition in a carbonate ramp environment while lime mudstone wackestone calcarenite and limestone breccia conglomerate facies often extensively slumped represent a carbonate slope environment stratigraphic relations suggest that the depositional environment evolved from a ramp into a slope through the dinantian two main sediment sources are indicated by the sequence an extra basinal terrigenous mud source and a supply of carbonate from the margins of the basin deposition from suspension and from sediment gravity flows in situ production and remobilization of sediment during sedimentary sliding were important processes operating within the basin periods of enhanced tectonic activity in the late chadian to early arundian and late asbian to early brigantian are indicated by basin wide horizons of sedimentary slide and mass flow deposits both intervals were marked by a decline in carbonate production resulting from inundation and uplift emergence the first of these intervals separates deposition on a seafloor with gentle topography carbonate ramp from a situation where major lateral thickness and facies variations were present and deposition took place in a carbonate slope environment the second interval marks the end of major carbonate deposition within the bowland basin and the onset of regional terrigenous sedimentation

breccia hosted manganese rich minerals of alpi apuane italy a marine redox generated deposit mn rich beds occur within the brecce di seravezza formation bsfm intercalated between norian metadolostone megalodontic marble and hettangian marble in the alpi apuane italy the bsfm is a rockfall talus deposit that accumulates at the base of the footwall scarp of normal faults bordering extensional marine coastal basins the type sequence of metabreccia ends with a bed of chloritoid schist interpreted as the metamorphic equivalent of lateritic soils the four main types of mn mineral assemblages are 1 braunite piemontite and rare hausmannite 2 piemontite braunite hollandite and minor rhodochrosite and kutnahorite 3 braunite hollandite and rare piemontite the other minerals are quartz calcite muscovite phlogopite baryte and minor hematite rutile and apatite during the alpine orogeny pressures of 4 6 kb and temperatures of 350 380 c were attained mn assemblages with hematite and phlogopite indicate o2 10 8 for t 350 c and o2 10 6 when braunite appears on the mn rich rocks ti fe nb sn ta hf th ga rb pr k na nd were identified as detrital in origin and are positively correlated with al u is positively correlated with co pb bi mo the rare earth element patterns normalized to seawater show a negative slope towards the heavy rare earth elements with positive ce anomalies in some samples positive ce and eu anomalies in other samples and negative ce and positive eu anomalies in a third group the eu concentrations are nearly constant and the eu anomalies reflect differences in the concentration of other rare earth elements for ce a positive correlation with al2o3 sio2 indicate that a detrital signature prevails on that produced by duration of seawater exposure but a significant good correlation of la tm lu with mg could indicate at least for these elements a seawater signature only in some samples ba eu sr show anomalously high concentrations likely of hydrothermal origin however generally in all the chemical variation diagrams the bsfm samples fall outside the field of hydrothermal and hydrogenous deposits as defined in the literature for other mn deposits in addition metabasites and metavolcaniclastic beds are absent from the bsfm sequence and bsfm coastal basins were for the most part separated from the open ocean and related streams that must be excluded as possible mn sources owing to the arid climate of late triassic the runoff was negligible and the groundwater oxidizing and alkaline were unable to mobilize mn the bsfm basins are then the most suitable depositional environment for mn the water column was stagnant and stratified only where bottom of the basin was deeper than the oxic anoxic boundary reducing marine bottom waters percolated within the fractured basement and leached mn from disseminated minerals of metamorphic rocks and then rising along fault and fractures supplied mn to the bottom waters afterwards when tectonic uplift and sealevel drop brought the bottom into the oxic field mn precipitated and formed the mn rich matrix of the bsfm deposits

carbonate platform flanks slope angle and sediment fabric more than 20 examples of fossil carbonate platform systems were compared for slope angle and sediment fabric plots of slope angle versus sediment fabric show that grainy non cohesive mud free sediments build steeper slopes than muddy cohesive sediments examples near the end members of grainy and muddy carbonate platform flanks are found in the triassic of the dolomites in northern italy and in the bahamas respectively they document the flank geometry and the processes readjusting the slope profile once the limiting slope angle is exceeded the grainy flank sediments in the dolomites modified by shearing and avalanching produce straight slope profiles with declivities up to 35 whereas the muddy bahamian flank sediments modified by large scale creep and rotational to translational sliding and slumping produce a concave upwards slope profile inclined at less than 4 the comparison between slope angle and sediment fabric indicates that the physical behaviour of sediments in the gravity field angle of shearing and mode of readjustment processes is linked to the composition of the slope sediment among the variables such as sea level subsidence climate plate motion and oceanographic setting windward leeward sediment fabric is suggested to be a major if not the major control on slope angle and slope curvature of carbonate platform flanks besides the recently documented tendency of carbonate sediments to build steeper slopes than siliciclastics this proposed relation sheds new light on the analysis and quantification of the variables influencing the geometry and depositional evolution of carbonate systems furthermore it provides an opportunity to deduce sediment composition from seismic lines and predict lithology prior to drilling

recharge and salination processes in the carbonate aquifers in israel limestone and dolostone aquifers play a major role in the water supply system of israel in many cases there are brackish to saline springs at their outlets the source of the saline water and the mechanism of salinization differ from place to place in some cases it is due to mixing with seawater mediterranean or dead sea at the fresh saline water interface while in other cases deepseated brines emerge along regional faults the general policy for reclaiming the fresh component of the water before mixing with the saline component is to try to catch the fresh water as far as possible upstream from the outlet in most cases this is the area where the mixing takes place the main case histories in israel are discussed in this paper

mixed carbonate siliciclastic sedimentation on a miocene fault block gulf of suez egypt abstract the miocene sediments at abu shaar red sea egypt include both carbonates and detrital silicates whose distribution is closely related to a pre miocene basement fault block as such they demonstrate the relationships between local distensional tectonics and sedimentation because of the vertical bathymetric relief of the basement block the carbonates include both a spectacular talus and massive platform facies in spite of the presence of scattered corals sedimentation is not truly reefal as deposits consist essentially of muddy bioclastic and silicate sands the most typical ecological elements are numerous spectacular stromatolites rigidity of the sedimentary mass was mainly induced by early marine cementation carbonate siliciclastic transitions on and around the abu shaar platform were determined mainly by basement morphology and related pre miocene tectonics

the importance of microbial binding in neogene quaternary steep slopes abstract the geometry and inclination of carbonate platform slopes are typically described as the result of the sediment texture components and grain size occurring in the slope three carbonate slopes from the holocene of the tongue of the ocean bahamas and three slopes from an upper miocene carbonate platform in se spain are investigated to identify the factors controlling dip angles although platforms differ in size and elevation with regard to the surrounding basin both locations present slopes with linear profiles and steep angles over 35 the slope facies in both locations are very similar with the matrix and some bioclasts presenting microfabrics that evidence microbial activity during deposition these include 1 clotted micrite patches locally connecting bioclasts or infilling primary pores 2 porostromate structures in the micrite 3 dense micritic masses 4 binding structures 5 micritic crusts and 6 peloidal textures the holocene and miocene depositional geometries and facies distribution are the response to various sedimentary processes including rockfalls gravity flows and in situ carbonate production extensive microbial binding is identified as the controlling factor for early stabilization of the slope which in combination with subsequent rapid cementation produces and maintains the steep slope angles consequently microbial induced stabilization of modern and neogene slopes is as significant as in paleozoic and triassic examples

chattermark trails surface features on detrital quartz grains indicative of a tropical climate abstract with respect to weathering erosional processes and sediment transport quartz is one of the most stable minerals and makes up to 98 of the mineral volume of siliciclastic sands pettijohn et al 1987 although a major component in a wide variety of rocks quartz has almost no characteristic properties that allow determining parent rock types quartz does not contain characteristic cleavage planes and quartz grains react to impact or collision with other sediment particles by producing conchoidal fractures very similar to those observed for broken glass for sedimentologists physical geographers and soil scientists detrital quartz grains are poor in characteristic features except for a suite of surface features that may be indicative of various transport environments or even climate related alterations one of these surface features are chattermark trails chattermark trails are a series of linearly arranged rune like grooves on surfaces of minerals grains such as quartz and garnet lacking any type of cleavage these trails have been described from many unconsolidated sediments and are attributed mostly to glacial sediments laboratory experiments on polished quartz beads reveal that chattermark trails are not primary surface features but become visible after etching by dilute hydrofluoric acid comparison of the etched and non etched surface of the same quartz bead reveals that mechanically produced invisible cracks related to blunt collisions with other polished quartz beads became visible only after chemical etching chattermark trails on detrital quartz grains are the product of two processes the dynamic one is an invisible transport related blunt collision followed by a second stationary process which enables quartz dissolution to make the chattermarks visible in the broad field of laterite research it is well accepted that quartz dissolution in surface or near surface deposits is restricted to stationary chemical weathering in a wet tropical or at least subtropical climate drawing on this information chattermark trails are no longer considered a product of a specific sedimentary environment but reveal a distinct history of the quartz grain they are formed by blunt collisions in a sediment transport stage before experiencing some dissolution during a depositional stage in a tropical climate grains can be remobilized in an active sediment transport system collectively the results reveal that chattermark trails on quartz grains provide unique insights into the transport and climate history of sediments

the hydrochemical evolution of brackish groundwater in central and northern sinai egypt and in the western negev israel summary cretaceous trans boundary aquifers in the central and northern parts of sinai egypt and the negev israel are geographically and geologically both contiguous and continuous hydrogeological and hydrochemical studies of these aquifers with disregard to political boundaries are scarce the lower cretaceous kurnub group aquifer in sinai and the negev hosts paleowater mostly replenished during the pleistocene the objectives of this study are to elucidate the relationship between regional structural elements and the salinization of groundwater in the kurnub group in sinai and further downstream in the negev the stable plateaus in southern sinai and the fold structures in the north continuing into the negev are separated by the w e striking minshara ramon shear zone with the exception of higher salinities in the north the chemical composition of kurnub group groundwater north and south of the shear zone is similar similarly groundwater in the overlying upper cretaceous aquifer differs from kurnub groundwater only within and north of the shear zone and is characterized by higher cl concentrations lower mg rca ratios due to high ca in the calcareous aquifer and by a heavier isotopic signature inverse hydrogeochemical modeling using phreeqc indicates that the increase in salinity of kurnub groundwater within the shear zone and in adjacent areas could be due to two different sources first the salinization process could be the result of mixing with sulfate rich brackish groundwater occurring in jurassic formations which are in fault controlled lateral contact with the kurnub group aquifer second the salinity differences could be from unflushed seawater in the subsurface of the northern sinai and western negev i e possible remnants of the post messinian lower pliocene transgression which penetrated into northern sinai the western negev and the coastal plain of israel both through erosional channels which were incised during the neogene and by flooding over outcrops of permeable formations

hydrodynamic evolution from quartz microtextures of a beach ridge in qinghai lake china abstract beach ridges are landforms that exist on beach shorelines and can supply abundant information regarding palaeoenvironments to better understand the hydrodynamic processes of beach ridges a quartz microtexture analysis was carried out in this study the microtextural features of a total of 1063 quartz grains from seven beach ridge samples and eight reference samples from rivers a dune and a nearby beach were observed and analysed by scanning electron microscopy the qualitative and quantitative results suggest that the quartz microtextures of the beach ridge samples present more fresh surfaces and percussion marks than the river samples but less angularity the upper sequence samples from the beach ridge present higher values of fresh surfaces and percussion marks and lower dissolution than the lower sequence samples a cluster analysis shows that the hydrodynamic conditions of qinghai lake underwent pronounced changes from weak to strong and then to weak at the present time furthermore quantitative analyses indicate that the beach ridge and river sedimentary environments can be distinguished through the microtextural features of the 250 125 m size fraction however more grain size fractions should be observed and analysed to interpret the hydrodynamic conditions the quartz microtextural analysis of beach ridges may be an effective method reflecting the palaeohydrodynamic conditions

synsedimentary fault control on the deposition of the duitschland formation south africa implications for depositional settings paleoproterozoic stratigraphic correlations and the goe abstract the paleoproterozoic great oxidation event goe marks the first significant oxidation of atmosphere and surface environments and is causally associated with the global disappearance of mass independent sulfur isotope fractionation mif s however fundamental sedimentary aspects of successions recording this event e g depositional environment tectonic setting and stratigraphic correlation are poorly constrained and often debated restricting full understanding of causes and effects related to the goe in south africa mif s disappears across the mid duitschland unconformity mdu in the duitschland formation transvaal supergroup new sedimentological observations of the lower duitschland formation have identified up to 5 times thicker and more diverse chert pebble conglomerates than previously documented new facies observed include lenticular conglomerates which incise cross bedded dolomites and imbricated conglomerates the overlying mdu is angular in nature recording an 15 n dip of the lower duitschland strata elsewhere it possesses a disconformable geometry a new depositional model is proposed where shallow marine carbonate ramp deposition interfaced with wave influenced gilbert type fan deltas in an isolated depocentre produced during synsedimentary faulting there is no evidence that the mdu formed due to direct glaciation as proposed previously however glacio eustatic changes may have had an influence this study supports the lithostratigraphic correlation of the duitschland and rooihoogte formations this interpretation challenges the idea that they are separate lithostratigraphic units that record oscillations in mif s this apparent oscillation in mif s is a stratigraphic artefact the correlation proposed in this study implies a unique mif s signal and has important consequences for differentiating true spatiotemporal oscillations in mif s chemistry from artificial variations caused by unresolved stratigraphic relations

kalkowsky s stromatolites revisited lower triassic buntsandstein harz mountains germany abstract the term stromatolite was proposed by kalkowsky 1908 z dt geol ges 60 68 125 for structures he discovered in the carbonates of the lower triassic buntsandstein of the harz mountains in central germany we have re examined these localities to clarify kalkowsky s descriptions and to deduce the environmental conditions of stromatolitic growth the lower buntsandstein was deposited in a closed lacustrine basin the central european permo triassic basin the depositional environment was a playa lake with variable salinity in the centre of the basin oolite beds are intercalated in the mainly siliciclastic succession which is composed of 20 fining upward cycles thought to have been produced by climatic variations stromatolites occur almost exclusively on the surface of oolite beds stromatolitic structures consist of millimetre thick laminated crusts and centimetre high branching columnar forms smaller and bigger 2 m high domes are composed of secondary order columns and intercalated crusts occasionally upper surfaces of the domes are pitted due to syndepositional dissolution despite of the overall intense sparitization two groups of stromatolitic microstructures can be distinguished spongy fenestrate and fan like fabrics the spongy fenestrate fabric is similar to that one caused by the recent cyanobacteria phormidium calothrix and dichothrix and the fan like fabric to rivularia laminated crusts called stromatoid by kalkowsky are interpreted as being of cement origin and formed by quick precipitation the change from columnar to domical forms may reflect changes of hydrodynamic conditions clear photoautotrophism suggests that cyanobacteria or eukaryotes were the dominant organisms involved in the formation of kalkowsky s stromatolites influx of ooids or siliciclastic mud interrupted or terminated the stromatolitic growth the morphology growth pattern and fabrics of stromatolites were most likely controlled by ecological factors which all seem to be related to the general hydro climatic evolution of the lower buntsandstein

the 2011 japanese 9 0 magnitude earthquake test of a kinetic energy wave model using coastal configuration and offshore gradient of earth and beyond abstract based on geological investigations of coastal geometry and stratigraphy offshore gradient variation wave velocity energy and quartz grain microtexture analysis of key sites inundated by tsunamis during the holocene we have developed a postulated model that could be used to assess modern and ancient onshore environmental conditions during tsunami emplacement given that tsunami waves can travel up to 900 km h the kinetic energy of the wave is determined by frictional release on the offshore slope to seabed nearshore sand and sediment supply and coastal geomorphology specifically coast linearity or embayments that constrict wave energy with gentle offshore gradients and relatively linear coastlines the kinetic energy of the tsunami is decreased by friction with the seabed and radiated outward along the coast thus producing reduced flooding of the affected coast and fewer collisions of entrained grains in contrast steep offshore gradients reduce friction to mere milliseconds of wave impact and embayments specifically narrow coastal constrictions increase wave energy both of which increase on land run up heights and importantly to our proposed model grain collision effects damage to quartz grains deposited by tsunamis along coastal extents ranges from slight on linear coasts with gentle offshore gradients to highly resurfaced mineral surfaces on coasts with steep offshore gradients and narrow embayments our model can be further tested through collection analyses and comparison of quartz grains in relatively low and high energy environments of the recently tsunami impacted northeastern coast of japan for example the location of the fukushima nuclear plant along a linear coastline with a less steep offshore gradient may have attenuated the energy of the incoming wave and thus yielding less resurfaced grains when compared to the coastline located to the north of sendai city where coastal embayments of variable size coupled with steep offshore gradients would produce higher energy waves of greater magnitude as attested by greater penetration inland with considerable loss of life and property damage and resulting highly deformed grain surfaces the model could be applicable for assessing modern and ancient coastal environmental conditions on earth and postulated ancient marine conditions on the red planet

a facies distribution model controlled by a tectonically inherited sea bottom topography in the carbonate rimmed shelf of the upper tithonian valanginian southern tethyan continental margin nw sicily italy the upper tithonian valanginian shallow water carbonates outcropping in the palermo mts nw sicily consist of several facies associations reflecting different depositional environments of a carbonate rimmed shelf pertaining to the southern tethyan continental margin the reconstructed depositional model based on the sedimentological features cyclic facies arrangement and biota distribution shows that a wide protected lagoon dominated by algae molluscs and scattered patch reefs was bordered landward by a tidal flat where stromatolitic algal mats were cyclically subaerial exposed and seaward by a marine sand belt and reef complex oolitic packstone grainstone lithofacies cyclically subjected to subaerial exposure suggests the occurrence of a barrier island located nearly to the lagoonal carbonate shoreline allowing the development of narrow embayments with restricted circulation in the outer platform the oolitic lithofacies of the marine sand belt pass landward into the protected lagoon where washover oolite sands occur and seaward into a high energy zone back reef apron gradually merging in the reef complex in the latter coral framestone occupied the inner sector reef flat while the facies association dominated by boundstone with ellipsactinia sp developed in the outer sectors reef wall adjacent to the fore reef and upper slope environments stratigraphic evidence associated with the recognized facies associations helped to reconstruct the geo tectonic setting of the carbonate platform where the distribution of the depositional facies along the shelf and their extension were influenced by the tectonically inherited sea bottom topography in a regime of extensional tectonics localized and thin succession of high energy prograding oolite sand belt depositional facies occupied structural highs footwall uplift while the largely diffused and thick low energy aggrading peritidal to lagoonal depositional facies developed in subsiding hanging wall the reef complex and the fore reef depositional facies exhibiting lateral migration and prograding geometries with clinoforms and downlap stratal terminations developed on a subsident stepped margin adjacent to a faulted shelf break this morphostructural setting can be comprised in a model where the tilted and faulted blocks inner platform and stepped margin outer platform paleo topography inherited from the rifting tectonics was the most important factor controlling the geometry and depositional architecture of a carbonate platform growing on the southern tethyan passive margin

hydrochemistry of groundwater at unique outlets of the bet shean harod multiple aquifer system israel abstract the bet shean and harod valleys are regional recipients and mixing zones for groundwater draining to these valleys from a multiple aquifer system which includes carbonate and basalt aquifers and deep seated reservoirs of brine the outlets of these aquifers are located at the mountain border separating the valleys from the gilboa and ramot issakhar mts the aquifers drain through two types of outlets unique and common the latter type is mainly conditioned by the occurrence of fault blocks acting as connecting media between the aquifers ionic ratios of groundwaters flowing through different carbonate aquifers have not sufficient contrast to facilitate precise identification of source aquifers in the case of basalt aquifers the ratios are unequivocal and sufficient contrast enables such an identification

microtextural analysis of quartz grains of tsunami and non tsunami deposits a case study from tirua chile abstract in order to estimate the tsunami hazard it is essential to reliably identify and differentiate tsunami deposits from other high energy events like storms recently the microtextural analysis of quartz grain surfaces was introduced as a method to differentiate between tsunami and other deposits using tsunami deposits sampled from a bank profile of the tirua river central chile an area that was significantly affected by the 2010 and 1960 chile tsunamis we tested the microtextural analysis method for its capability to identify tsunami deposits a total of 815 quartz grain surfaces of two tsunami layers two non tsunami marsh sediment samples and three reference samples from nearby beach dune and river were analyzed using scanning electron microscopy sem we grouped the detected microtexture features into five microtextural families angularity fresh surfaces percussion marks adhering particles and dissolution features both the tsunami deposits and reference samples reveal high numbers of fresh surfaces and percussion marks thus there are no statistically significant differences between tsunami beach dune and river deposits in characteristics and abundances in all microtextural families our study indicates that the microtextural analysis of quartz grains may not be a suitable method to identify tsunami deposits in tirua chile due to local factors such as high numbers of inherited microtextures and the possible effects of the high amount of heavy minerals

oxygen 17 anomaly in soil nitrate a new precipitation proxy for desert landscapes abstract the nitrogen cycle in desert soil ecosystems is particularly sensitive to changes in precipitation even of relatively small magnitude and short duration because it is already under water stress this suggests that desert soils may have preserved past evidence of small variations in continental precipitation we have measured nitrate no 3 concentrations in soils from the atacama chile kumtag china mojave us and thar india deserts and stable nitrogen and oxygen isotope 15 n 17 o and 18 o abundances of the soil no 3 17 o anomalies 17 o the deviations from the mass independent isotopic fractionation were detected in soil no 3 from almost all sites of these four deserts there was a strong negative correlation between the mean annual precipitation map and soil no 3 17 o values o no 3 soil 17 this map o no 3 soil 17 correlation advocated o no 3 soil 17 as a new precipitation proxy and was then used to assess precipitation changes in southwestern us at the pliocene pleistocene boundary in south america during the miocene and the sahara desert in the past 10 kyr using no 3 17 o in paleosols or ancient aquifers global and the us maps of surface o no 3 soil 17 were also projected with available map datasets based on the map o no 3 soil 17 model

miocene sandstone provenance relations in the gulf of suez insights into synrift unroofing and uplift history time compositional relations inferred from point counts of 46 upper oligocene to middle miocene syn rift sandstones from gulf of suez outcrops are used to further constrain the uplift and unroofing history of this neogene continental rift although earliest rifting began by approximately 24 ma as evidenced by minor basaltic volcanism the main phase of crustal extension tectonic subsidence of the axial trough and rift margin uplift began approximately 19 ma oligocene and basal miocene nukhul formation sandstones are dominated by monocrystalline quartz and clasts derived from only the youngest pre rift strata eocene indicating that relief was probably less than 200 m until 20 ma the lower miocene rudeis formation records both major subsidence in the axial trough and peak unroofing of the pre rift sedimentary sequence from 19 16 ma middle miocene sandstones derived from the kareem and belayim formations are increasingly dominated by crystalline basement derived detritus recording rapid increase in rift margin relief after approximately 14 ma diachronism in the first appearance of unroofed basement detritus across the rift indicates uplift of the western margin may have preceded that of the eastern margin by as much as 2 m y once rapid uplift began between about 20 17 ma unroofing of a maximum of 1000 m of the pre rift strata occurred in less than 2 m y

chemical composition of rainfall and groundwater in recharge areas of the bet shean harod multiple aquifer system israel the bet shean and harod valleys are regional recipients and mixing zones for groundwaters draining from a regional multiple aquifer system comprising two different carbonate and two basalt aquifers as well as deep seated reservoirs of confined brines this paper the first of two describes the hydrochemistry of the groundwater bodies related to this multiple aquifer system the paper deals with the chemical composition of rain falling on natural recharge areas the chemical contribution of the aquifer rocks and the chemical evolution of groundwaters in the upper flow courses of all aquifers of this regional system the methodology applied is based on the determination of major dissolved ions and on the examination of their ratios and changes along the upper flow paths rain water falling on natural recharge areas has an average chlorinity of 12mgl 1cl and a calcium bicarbonate composition caused by dust borne terrigenous material this rain water salinity decreases with distance from the sea shore fresh groundwaters flowing through the different aquifers may be identified and differentiated by their characteristic salinity levels and ionic ratios groundwaters flowing through carbonate aquifers are identified by different salinity levels and by distinct rmg rca ratios reflecting dolomite calcite ratios in aquiferr rocks the groundwaters of the two basalt aquifers have typical cation assemblages and high na and mg2 concentrations far in excess of those typical of the recharging rainfall groundwater in the upper flow courses of all aquifers investigated is deficient in so2 4 and k relative to recharging rain water

carbonate platforms of passive extensional continental margins types characteristics and evolution abstract carbonate platforms of extensional margins may be grouped into several major categories homoclinal ramps have gentle slopes into deep water may have skeletal or ooid pellet sand shoal complexes that grade without break in slope into deep ramp nodular limestone and then into pelagic hemipelagic basin facies they generally lack significant slump and sediment gravity flow deposits in the deeper water facies distally steepened ramps differ from the above in having a marked increase in slope at the seaward edge of the deep ramp and abundant slumps slope breccias and turbidites however clasts of shallow platform margin facies are generally absent from breccias rimmed shelves have linear trends of shelf edge lime sands and reefs a marked increase in slope into deep water and foreslope and slope sands breccias with clasts of platform margin rocks and turbidites grading seaward into basin hemipelagic pelagic muds they may be divided into accretionary bypass and erosional margins isolated platforms are broad flat topped shallow platforms surrounded by deeper water few hundred meters to 4 km deep many are bypass margins but accretionary and erosional margins also occur finally incipiently to completely drowned or open platforms may develop by rapid submergence of ramps shelves or isolated platforms shallow platform margin facies are shifted landward and the earlier shallow water platform is covered with transgressive lags and deeper water blankets of hemipelagic or pelagic facies or open marine whole fossil wackestone the carbonate prisms commonly develop above a basal clastic phase ramps develop early and evolve into rimmed shelves however with drowning rimmed shelves may evolve up into ramps rimmed shelves may also develop into ramps where miogeoclinal faces prograde into filling marginal basins carbonate miogeocline deposition terminates when the shelf becomes a prograding clastic shelf or where it becomes part of a collisional orogen the various platform types may be recognized from continental margin sequences ranging from proterozoic to holocene in age

research on the lithofacies and paleogeography of the lower cambrian xiaoerbulake formation in the northern tarim basin northwestern china based on the study of cores thin sections and outcrops the sedimentary facies of the lower cambrian carbonate rocks in the northern tarim basin can be divided into four types restricted platform

surface textural analysis of quartz grains by scanning electron microscopy sem from sample preparation to environmental interpretation abstract surface microtextures on quartz grains provide an insight into the sedimentary history of clastic sediments not only information on the depositional environment is provided but also in some cases successive sedimentary cycles can be recognised sample preparation and sem imaging are the initial and therefore crucial steps in the study of microtextures a sample preparation procedure using 15 hydrochloric acid and 50 g l tetrasodium pyrophosphate solutions removes most of the grain coatings and adhering particles the study of microtextures on 1300 quartz grains from a wide variety of environments was complemented with the reference works and atlases krinsley and doornkamp 1973 le ribault 1977 higgs 1979 mahaney 2002 to construct an interpretation scheme allowing to differentiate between fluvial marine eolian glacial and diagenetic alteration environments based on microtextures in a case study the known littoral setting of two samples was confirmed by using the interpretation scheme for quartz microtextures furthermore successive reworking of the grains in eolian and intertidal environments was recognised by presenting the research of microtextures from starting point to interpretation new researchers may find this review a useful and practical introduction into the technique

carbonate apron models alternatives to the submarine fan model for paleoenvironmental analysis and hydrocarbon exploration sediment gravity flow deposition along the deep water flanks of carbonate platforms typically does not produce submarine fans rather wedge shaped carbonate aprons develop parallel to the adjacent shelf slope break the major difference between submarine fans and carbonate aprons is a point source with channelized sedimentation on fans versus a line source with sheet flow sedimentation on aprons two types of carbonate aprons may develop along relatively gentle 4 platform margin slopes aprons form immediately adjacent to the shallow water platform and are referred to as carbonate slope aprons along relatively steep 4 15 platform margin slopes redeposited limestones accumulate in a base of slope setting by passing an upper slope via a multitude of small submarine canyons and are referred to as carbonate base of slope aprons both apron types are further subdivided into inner and outer facies belts inner apron sediments consist of thick mud supported conglomerates and megabreccias facies f as well as thick coarse grained turbidites facies a interbedded with subordinate amounts of fine grained peri platform ooze facies g outer apron sediments consist of thinner grain supported conglomerates and turbidites facies a as well as classical turbidites facies c with recognizable bouma divisions interbedded with approximately equal proportions of peri platform ooze facies g seaward aprons grade laterally into basinal facies of thin base cut out carbonate turbidites facies d that are subordinate to peri platform oozes facies g carbonate base of slope aprons grade shelfward into an upper slope facies of fine grained peri platform ooze facies g cut by numerous small canyons that are filled with coarse debris as well as intraformational truncation surfaces which result from submarine sliding in contrast slope aprons grade shelfward immediately into shoal water platform margin facies without an intervening by pass slope the two carbonate apron models presented here offer alternatives to the submarine fan model for paleoenvironmental analysis and hydrocarbon exploration for mass transported carbonate facies

climatic signatures in shallow water carbonates high resolution stratigraphic markers in structurally controlled carbonate buildups late miocene southern spain abstract neogene intramontane basins of the betic cordillera se spain have a complex tectonic and sedimentary history in the eastern almeria province movements along the carboneras strike slip fault system n50 e and its conjugated faults n140 e controlled the distributions of depocenters and stratigraphic architectures of late miocene sediments we have chosen the agua amarga area 1 to exemplify the potential of climatic signatures of biogenic associations in shallow water carbonates for high resolution chronostratigraphic correlations and 2 to describe stratigraphic architectures and facies distributions in a setting subject to synsedimentary tectonics the southwestern margin la higuera is formed by a gentle ramp dipping in a n50 e direction late tortonian and messinian deep and shallow water carbonates divide into eight depositional units neptunian autoclastic breccias neptunian dikes and submarine biogenic pavements unit h 1 document rapid flooding of the basin during a phase of intense tectonic dilatation late tortonian units h 2 7 late tortonian early messinian form wedges which dip and thicken in a basinward direction little lateral facies change and internal stratifications parallel with the basal surfaces imply deposition on a subhorizontal substratum the upper bounding surfaces are erosional and formed by truncation of tilted strata from wedge to wedge the angle of dip decreases upsection and is near zero in between the last units which have parallel bounding surfaces and rest subhorizontally unit h 7 8 this pattern results from cumulative rotational uplift which decreased upward but does not necessarily exclude vertical displacements of the youngest units the southeastern margin of the basin is mostly eroded but may have trended n50 e as indicated by the distribution of slumped reef blocks a relict of the margin is preserved at mesa de roldan and exhibits steep clinoforms dipping towards the nw n300 e and w n250 e synsedimentary tectonics are documented by nine shallow marine depositional units unit r 1 conglomerates associated with neptunian dikes units r 2 9 skeletal carbonates and reefs bounded by deep erosion surfaces and or truncation of individual units along a miocene fault at both flanks the shallow water biofacies record an identical trend of climatic warming and therefore bracket a similar amount of time temperate conditions prevailed during the latest tortonian and earliest messinian whereas tropical temperatures existed during the early and late messinian and perhaps during the tortonian messinian transition the number of depositional units reflecting these climatic periods of time and the stratal geometries however differ at both sites and within the basin which implies spatial variations in the generation of accomodation space on independent fault blocks these data also suggest that there cannot be any universal sequence stratigraphic model for late miocene shallow water carbonates of se spain and that the downstepping geometries observed in many other early messinian reefs of the betic cordillera reflect tectonic uplift

the provenance of beach sediments on rhodes southeastern greece indicated by sediment texture composition and roundness abstract the texture composition provenance and transport of beach sediments and the roundness of sediment grains were studied on the coasts of the island of rhodes in southeastern greece all the studied beaches are intermediate or high carbonate beaches where the texture and mineral composition of beach sediments and roundness of sediment grains display some degree of local variation beach sediments consist mainly of medium and coarse sand and granule gravel being moderately or poorly sorted symmetrical or negatively skewed and leptokurtic or very leptokurtic on pocket beaches the mineral composition is closely related to nearby exposed coastal formations sea cliffs bluffs and rocks the grain size frequency distributions of beach sediments being nearly normal and the roundness of sediment grains good where rivers discharge on to the beach or near to it the mineral content of these beaches is related both to the formations situated inland in the catchment basins of the rivers and to coastal formations river sediments 55 60 and coastal abrasion sediments 40 45 on shores are mixed by waves and littoral drift low mg calcite and quartz are the most common minerals in the beach sediments of rhodes the other common minerals are dolomite feldspars olivine and magnetite the sources being mainly the ophiolites on the mountains of northern rhodes the direction of net littoral drift is determined mainly by the predominant wind and waves approaching from the direction of the greatest fetch these same waves determine to a large extent the direction of seasonal littoral drift in the beach and swash zones whereas in the surf zone on the nw coast of rhodes it is determined mainly by the prevailing wind and waves

lower miocene nukhul formation gebel el zeit egypt model for structural control on early synrift strata and reservoirs gulf of suez the aquitanian early burdigalian lower miocene nukhul formation at gebel el zeit egypt was deposited during early stages of gulf of suez rifting the unit dips 8 15 less than underlying prerift strata indicating that significant rotation and extension preceded subsidence of the gebel el zeit fault block the nukhul formation at gebel el zeit is up to 75 m thick in outcrop and consists of a lower sandstone and an upper carbonate unit the formation varies considerably along strike because of syndepositional differential movement of small fault bounded blocks the lower clastic unit at south gebel el zeit contains poorly sorted conglomeratic marly sandstone that commonly displays grading and bouma sequences beds were deposited below storm base by sediment gravity flows thicker intervals are inferred to fill small structurally controlled submarine gullies that funneled sand and gravel southwestward to a half graben basin in contrast an inferred correlative thin basal conglomeratic unit in north gebel el zeit was deposited in a shallow marine setting the presence of basement clasts in nukhul strata indicates early syndepositional uplift due to structural tilting the upper carbonate unit consists of bioclast peloid and intraclast packstone wackestone and grainstone with minor floatstone rudstone and coral algal boundstone carbonate strata were deposited variously in deep marine low energy peritidal and subtidal and reefal environments deeper submerged blocks were the site of carbonate resedimentation or deeper shelf deposition reefs and shallow marine bioclast shoals formed on higher submerged blocks nukhul strata show that synrift reservoir prediction in the gulf of suez the red sea and presumably in other rifts requires mapping of synrift cross faults and fault block by fault block facies analysis robert winn is a consulting geologist he received a ph d from the university of wisconsin madison in 1975 and joined marathon oil company as a research geologist in 1977 he left marathon in 1994 for the university of papua new guinea where he was senior lecturer and then associate professor he was head of the geology department from 1996 to 2000 his primary interests are in clastic sedimentology and sequence stratigraphy paul crevello is a consulting geologist and technical director of petrexasia which he formed in 1997 he received an m s degree from the university of miami 1978 and a ph d from colorado school of mines 1989 he was employed by marathon oil as a research geologist from 1978 to 1994 and by the university of brunei as senior lecturer from 1994 to 1997 his specialties are in sequence stratigraphy and sedimentology of carbonate and turbidite systems and the integrated calibration of 3 d reservoir models william bosworth is employed by marathon oil company he joined marathon in 1984 and has worked principally on international exploration and development projects from 1980 to 1984 he taught structural geology and tectonics at colgate university in hamilton new york his research interests are principally in extensional tectonics continental stress field evolution and the paleogeodynamics of the african plate

modern carbonate siliciclastic transitions humid and arid tropical examples climate and tectonic setting largely control characteristics of transitions between carbonate and siliciclastic sediments in depositional systems three examples selected from both humid and arid tropical settings are discussed order to illustrate details of these relationships the eastern shelf area of nicaragua is an area where siliciclastic and carbonate sediments actively interfinger under humid tropical conditions extremely high rainfall 4 5 m yr 1 in the southern part of coastal plain coupled with a correspondently high sediment flux to the nearshore shelf results in an inner shelf that is dominated by siliciclastics density gradients and persistent momentum provided by the trade winds force turbid coastal waters to the south and confine siliciclastic sediments to a coast parallel zone approximately 20 km wide the remainder of the broad shelf is characterized by carbonate sediments and reefs the mid shelf area has a coarse carbonate sediment cover composed largely of the calcareous green alga halimeda the outer shelf displays rugged topography associated with reef development skeletal carbonates containing abundant coral and coralline algal grains are characteristic of the seaward margin of the shelf significant amounts of siliciclastic sediment are confined to the nearshore part of the shelf and the transition from siliclastics to carbonates occurs over a distance of 20 km or less a second example from the humid tropics focuses on the living reefs of indonesia that are surrounded by fine grained siliciclastics a warm rainy climate results in rapid weathering of volcanic rocks from the indonesian archipelago and abundant sediment input to the shallow 40 70 m deep sunda shelf in the northern hemisphere winter monsoonally driven marine processes rrive water and sediment to the east down the axis of the java sea during summer the direction of transport is reversed this bidirectional process regime not only leaves its imprint in reef and carbonate platform morphology but also results in widespread distribution of siliciclastics from adjacent source areas isolated reefs as well as small and generally elongate reef rimmed carbonate platforms 0 5 10 km long rise 40 50 m above a sea floor composed largely of siliciclastic sediments in these cases facies transitions are very abrupt until environmental conditions curtail the carbonate producing communities of these platforms carbonate buildups and associated skeletal sediments will coexist with wider spread and more abundant siliciclastics a third example from a low latitude arid setting shows that facies transitions from carbonates to siliciclastics typically take place over short distances the lack of significant rainfall coupled with high relief along fault controlled basin margins promotes aperiodic but powerful episodes of siliciclastic that build directly into the marine environment high sloping and narrow coastal plains composed of overlapping fans result the steep seaward ends of these fans are maintained and protected from marine erosion by coral reefs and associated carbonates regionally siliciclastic to carbonate facies changes in these arid settings take place over very shor distances a few kilometers at most however on a local scale carbonates may be replaced by siliciclastics over distances as small as a few tens of meters

paleoclimatic controls on sedimentation diagenesis and reservoir quality lessons from miocene carbonates miocene carbonates worldwide were deposited in a wide range of paleogeographic and tectonic settings and form important reservoirs in several regions the reservoir quality of these carbonates appears to have been primarily controlled by the prevailing paleoclimate which exerted a major control on both the depositional patterns and diagenetic pathways two end members are discussed here 1 humid oceanic tropical subtropical settings and 2 arid land locked temperate subtropical settings in humid oceanic tropical subtropical settings e g miocene of southeast asia a warming trend paralleled by generally rising sea level allowed thick coral reefs and skeletal banks to develop most of which are seismically resolvable these carbonates typically represent several stages or cycles of development largely third order separated by discontinuities in platform growth with episodic subaerial exposure development of economic reservoirs is mainly related to relative sea level falls and associated meteoric diagenesis trends and patterns of reservoir distribution can be predicted within a sequence stratigraphic framework basal transgressive carbonates are mostly tight because of their relatively fine grained textures intense compaction and isolation from meteoric water influence best reservoir quality is commonly developed beneath subaerial unconformities in highstand buildups where effects of meteoric water leaching and karstification are most intense in contrast in arid land locked subtropical temperate settings unfavorable environmental conditions caused by periodically increased salinity and probably relatively low temperature restricted the full growth of carbonate buildups as a result relatively thin and narrow fringing coral reefs with small poorly developed lagoons in rhodalgal ramps are the most common facies type in the upper miocene of the mediterranean and the middle miocene of the gulf of suez and red sea whereas the lower miocene of the middle east is characterized by low energy shallow shelfal and lagoonal carbonates under arid climatic conditions recharge of fresh groundwaters is limited thus minimizing meteoric dissolution and cementation during subaerial exposure instead sea level fall and lowstand ommonly resulted in extensive evaporitic conditions hypersaline brines originated within evaporitic basins or lagoons were the main cause of the pervasive dolomitization leaching of metastable skeletal grains and generation of moldic vuggy and intercrystalline porosity often associated with these arid land locked carbonates is the widespread anhydrite cement that precipitated over a wide range of burial depths porosity distribution in these carbonates thus depends not only on the original depositional fabrics but more importantly on the degree to which the porosity occluding anhydrite cement was dissolved or the low permeability carbonates were fractured these miocene examples illustrate the contrasting diagenetic patterns and reservoir styles controlled by paleoclimatic and paleoceanographic trends and demonstrate the importance of the often overlooked hypersaline diagenesis in arid land locked subtropical temperate settings the development of exploration and production strategies for carbonates that were deposited in different climatic settings should acknowledge and use these fundamentally different styles of diagenesis and reservoir characteristics

miocene platform margin reefs gulf of suez egypt jebel abu shaar is a completely dolomitized carbonate platform atop a crystalline basement horst on the western side of the gulf of suez margins of the platform where not removed by synsedimentary faulting are formed by well developed coral reefs the massive reef carbonates consistently illustrate two stages of growth a basal paucispecific unit of branching coral bafflestone mostly stylophora and a thicker upper unit of diverse coral framestone dominated by faviids in the upper unit the reef crest is massive columnar porites and less common caulastrea framestone the back reef is a framestone of diverse faviids mainly montastrea favites and tarbellastrea and interbedded reef flat rhodolite rudstones the back reef and reef flat facies grade onshelf into stylophora bafflestone biostromers and faviid bioherms the reef front is a shallow to intermediate depth zone of numerous and diverse faviids dominated by montastrea and acanthastrea framestones bioclastic sands and hardgrounds deeper zones are mostly small acanthastrea mounds or rhodolite bivalve rudstones with scattered faviids and acanthastrea synsedimentary lithification internal sedimentationm and bioerosion prevail throughout a deep water slope parallel biostrome of ahermatypic corals dominated by dendrophyllia and containing numerous balanophyllia and madracis is present 10 km north of abu shaar corals are well cemented by numerous rinds of marinemore cement which is overlain by geopetal internal sediment containing planktonic foraminifers and pteropods less

the geometrical evolution of normal fault systems abstract the purpose of this paper is to examine the kinematic behaviour of normal fault systems and see what general conditions govern their geometrical evolution we pay particular attention to seismological and surface data from regions of present day active normal faulting as the instantaneous three dimensional geometry at the time of fault movement is better known in active regions than in areas where the faults are now static most normal faults are concave upward or listric this shape can be produced by geometric constraints either because the faults reactivate curved thrusts or because they must be curved to accommodate rotations another effect which will produce curved faults is the variation of rheology with depth brittle failure at shallow depths produces less fault rotation than does distributed creep in the lower part of the crust an important geometric feature of normal faulting is the uplift of the footwall the amount of such uplift is related not only to the elastic properties of the lithosphere but also to the throw and dip of the fault a striking feature of active normal faults is that they occur in groups in which all the faults dip in the same direction this behaviour arises because the faults cannot intersect if they do one must cease to be active the rotation which such fault systems produce reduces the dip of the faults until a new steeply dipping fault is formed once a new fault cuts pre existing faults the earlier faults become locked and a new set of faults must propagate rapidly across the whole region involved many of these geometric constraints also apply to thrust faulting

petroleum geology and potential hydrocarbon plays in the gulf of suez rift basin egypt the gulf of suez in egypt has a north northwest south southeast orientation and is located at the junction of the african and arabian plates where it separates the northeast african continent from the sinai peninsula it has excellent hydrocarbon potential with the prospective sedimentary basin area measuring approximately 19 000 km 2 and it is considered as the most prolific oil province rift basin in africa and the middle east this basin contains more than 80 oil fields with reserves ranging from 1350 to less than 1 million bbl in reservoirs of precambrian to quaternary age the lithostratigraphic units in the gulf of suez can be subdivided into three megasequences a prerift succession pre miocene or paleozoic eocene a synrift succession oligocene miocene and a postrift succession post miocene or pliocene holocene these units vary in lithology thickness areal distribution depositional environment and hydrocarbon importance geological and geophysical data show that the northern and central gulf of suez consist of several narrow elongated depositional troughs whereas the southern part is dominated by a tilt block terrane containing numerous offset linear highs major prerift and synrift source rocks have potential to yield oil and or gas and are mature enough in the deep kitchens to generate hydrocarbons geochemical parameters sterane distribution and biomarker correlations are consistent with oils generated from marine source rocks oils in the gulf of suez were sourced from potential source rock intervals in the prerift succession that are typically oil prone type i and in places oil and gas prone type ii or are composites of more than one type multiple types i ii or iii for oil prone oil and gas prone or gas prone respectively the reservoirs can be classified into prerift reservoirs such as the precambrian granitic rocks paleozoic cretaceous nubian sandstones upper cretaceous nezzazat sandstones and the fractured eocene thebes limestone and synrift reservoirs such the miocene sandstones and carbonates of the nukhul rudeis kareem and belayim formations and the sandstones of south gharib zeit and

recharge mechanisms and geochemical processes in a semi arid sedimentary basin eastern cape south africa abstract stable isotope 18 o and 2 h and geochemical signatures are used to gain some insight into recharge processes and groundwater salinization mechanisms in a semi arid rangeland catchment the 665 km 2 catchment is underlain by fractured lower beaufort sandstones and mudstones and is intruded by several dolerite dykes chloride and isotopic relationships suggest that chloride ions in ground water are of meteoric origin the hypothesized recharge and salinization mechanism is that large storm events periodically dissolve accumulated surficial meteoric salts and after a period of evaporative enrichment at or near the soil surface leach them into the ground water geochemical variations imply that spatial differences exist in recharge volumes in evaporative enrichment or in the extent of leaching of surficial salts meteoric sodium chloride contributes greater than 90 of the dissolved sodium except at low salinities where cation exchange processes yield additional sodium inputs in exchange for dissolved calcium and magnesium at high salinities this process reverses and sodium is adsorbed releasing calcium and magnesium this process accounts for up to 40 of the dissolved calcium and magnesium contributions from geochemical weathering are relatively uniform in spite of highly variable salinities which implies that residence times are also relatively uniform

earthquakes recorded stratigraphically on carbonate platforms the longest records of earthquake activity1 may be preserved near the edges of carbonate platforms where reefs have bordered active faults because the carbonate sediments build up almost to low tide level because their character and lithification are very sensitive to deviations from that datum and because they commonly lithify soon after deposition2 strata can precisely record changes in lithospheric flexure3 which in turn record the buildup and release of elastic strain energy during stick slip faulting the approximate stratigraphy is predictable for a given history of faulting comparison of predictions with observations leads to an explanation for some of the hemicyclic sedimentary sequences common4 6 on carbonate platforms these records are important for characterizing the seismicity of atlantic type continental margins in general after rifting faults evidently remain active7 but major earthquakes are so rare that their recurrence times cannot be established from direct observations

a genetic classification of carbonate platforms based on their basinal and tectonic settings in the cenozoic abstract this paper reassesses the usefulness of the morphological classification of carbonate platforms into rimmed shelves and ramps whilst the existing classifications have value in describing platform margin morphology at any one time the terms rimmed shelf and ramp are less successful at categorising the entire morphology and stratigraphy of carbonate platforms research on cenozoic carbonate platforms from a range of different tectono stratigraphic settings indicates that the basinal and tectonic setting of a platform can be used to erect a first order genetic classification of carbonate platforms the basinal and tectonic setting of carbonate platforms is shown to control their occurrence the overall 3 d platform morphology the large scale stratigraphic features and depositional sequences climate ocean chemistry and biological evolution control grain types facies and some elements of platform margins but not the larger scale features considered in this new classification from a review of well exposed outcropping and seismically imaged cenozoic platforms it is proposed that eight types of carbonate platform can currently be recognised and characterised based on their basinal and tectonic setting fault block salt diapir subsiding margin offshore bank volcanic pedestal thrust top delta top and foreland margin carbonate platforms these eight types are described using information from cenozoic platforms worldwide and the controls on their development are discussed many platform types e g subsiding margin offshore bank salt diapir thrust top and foreland margin are typical of particular classes of sedimentary basins others e g fault block volcanic pedestal and delta top are more widespread in their occurrence and occur in a range of basin types the value of this classification is that it is genetic rather than morphological the classification reflects the entire morphology and large scale stratigraphy of the platform and the controls on its development in addition the platform models can be used to understand the details of less well exposed or seismically imaged platforms so that they can be characterised and understood in terms of tectono sedimentary processes conversely the classification also provides valuable information on basin evolution as carbonate platforms house information on palaeoenvironments sea level change and are sensitive recorders of the tectonic environment

hydrochemical variation in the springs water between jerusalem ramallah mountains and jericho fault palestine the spatial and temporal changes of the composition of the groundwater from the springs along the wadi qilt stream running from the jerusalem ramallah mountains towards the jericho plain is studied during the hydrological year 2006 2007 the residence time and the intensity of recharge play an important role in controlling the chemical composition of spring water which mainly depends on distance from the main recharge area a very important factor is the oxidation of organics derived from sewage and garbage resulting in variable dissolved co2 and associated hco3 concentration high co2 yields lower ph values and thus under saturation with respect to calcite and dolomite low co2 concentrations result in over saturation only at the beginning and at the end of the rainy season calcite saturation is achieved the degradation of dissolved organic matter is a major source for increasing water hardness besides dissolution of carbonates dissolved species such as nitrate chloride and sulfate are leached from soil and aquifer rocks together with only small amounts of mg mg not only originates from carbonates but also from mg cl waters are leached from aquifer rocks leaching of mg cl brines is particularly high at the beginning of the winter season and lowest at its end two zones of recharge are distinguishable zone 1 represented by ein fara and ein qilt is fed directly through the infiltration of meteoric water and surface runoff from the mountains along the eastern mountain slopes with little groundwater residence time and high flow rate the second zone is near the western border of jericho at the foothills which is mainly fed by the under groundwater flow from the eastern slopes with low surface infiltration rate this zone shows higher groundwater residence time and slower flow rate than zone 1 groundwater residence time and the flow rate within the aquifer systems are controlled by the geological structure of the aquifer the amount of active recharge to the aquifer and the recharge mechanism the results of this study may be useful in increasing the efficiency of freshwater exploitation in the region some precautions however should be taken in future plans of artificial recharge of the aquifers or surface water harvesting in the wadi because of evaporation and associated groundwater deterioration the runoff water should be artificially infiltrated in zones of wadis with high storage capacity of aquifers natural infiltration along the wadis lead to evaporation losses and less quality of groundwater

saline groundwater in israel its bearing on the water crisis in the country abstract one of the major causes for the deterioration of water quality bearing heavily on the water crisis in israel is the ongoing contamination of its water resources by saline water bodies the present paper reviews the geochemical processes forming saline water lists and explains certain chemical and isotopic parameters which enable understanding these processes and describes the saline groundwater bodies and various salinization phenomena occurring in the country s various aquifers deterioration of groundwater in israel is caused by numerous natural processes such as encroachment of sea water migration of connate highly pressurized brines penetrating into fresh groundwater by subsurface dissolution of soluble salts originating in surrounding country rocks and by water rock interaction in addition to sea water two saline water bodies were identified as the main factors causing salinization of fresh groundwater a ca chloride brines encountered in the jordan dead sea rift valley in various parts of the negev and of the coastal plain and b na chloride saline water identified in the subsurface of the negev and in the southern part of the coastal plain intensive exploitation of groundwater in israel has disturbed the natural equilibrium which prevailed between fresh and saline water the newly established groundwater flow regimes have facilitated the migration of saline water bodies their participation in the active hydrological cycle and the progressive contamination of fresh groundwater these processes which were not anticipated by planners and water resources managers emphasize that large scale groundwater exploitation was undertaken without giving sufficient consideration to the occurrence and subsurface migration of saline water and brines

the hydrochemical identification of groundwater flowing to the bet she an harod multiaquifer system lower jordan valley by rare earth elements yttrium stable isotopes h o and tritium abstract the bet she an and harod valleys in israel are regional recipients and mixing zones for groundwater draining from a multiple aquifer system which includes carbonate and basalt aquifers and deep seated pressurized brines the aquifers drain through two types of outlets distinct and mixed the latter type is mainly conditioned by the occurrence of fault blocks related to the jordan rift system which act as connecting media between the aquifers and facilitate interaquifer flow conjoint application of rare earth element distribution and water isotopes enables detection of the local areas replenishment by rainfall infiltration and in connection with the position of wells or springs the identification of groundwater flow paths once stationary equilibria are established changes of rey composition between rey in groundwater and their surface adsorption are negligible in areas with little soil coverage and vegetation even recharge over young tertiary and diagenetic cretaceous limestones is distinguishable by their rey distribution patterns groundwater recharged over tertiary limestones show higher rey abundance and more significant ce anomalies than those derived from the cretaceous limestones weathering of alkali olivine basalts leads to rey patterns in groundwater depleted in the middle ree the improved knowledge of the hydrological systems is thought to be useful for regional hydrogeological modeling and for designing rational water management schemes

developing carbonate platforms southern gulf of suez northern red sea abstract the ashrafi reef complex represents two small 8 10 2 km carbonate platforms and associated shoals located along the western side of the jubal strait at the gulf of suez s southern end these features are developing in an active marine environment that is operating within the geologic constraints of a tectonic trough characterized by mountainous fault controlled margins origin of the platforms is uncertain but the present morphology appears to be a product of the dynamic marine setting in which they are developing tidal flow between the red sea and the gulf results in strong rectilinear currents commonly 50 cm s 1 of the current velocities 5 10 cm s 1 can be attributed to surface currents driven by a regional unidirectional wind that blows from north to south down the axis of the gulf throughout the year side scan sonar data coupled with echo sounder profiles direct observations via scuba and bottom sampling indicate that the ashrafi platforms are actively building northward by windward reef accretion and extending to the south by sediment transport and accumulation the drumstick shape is a product of wave induced reef development along the northern margin and sediment distribution forced by strong tidal currents which coupled with unidirectional wind drift favors net transport to the south small reefs and hard grounds along the downdrift platform flanks assume a linearity consistent with the long axis of the platform the intensely mounded sediment of the platform flanks suggests that bioejection of particles in the mound building process together with a strong flow field is a downdrift sediment transport agent although the ambient salinity of surrounding gulf water is 41 platform top water masses were measured at 47 a lack of significant coral growth on the shallow platform top and the almost total exclusion of sediment producing calcareous green algae may be related to these hypersaline conditions sediments for the platform flanks are largely provided by the breakdown of platform margin reef communities and in situ organisms largely foraminifera

hydrochemical changes induced by overexploitation of groundwater at common outlets of the bet shean harod multiple aquifer system israel abstract the bet shean and harod valleys are regional recipients and mixing zones for groundwaters draining into them from a multiple aquifer system which includes carbonate and basalt aquifers and deep seated reservoirs of brine the aquifers drain through two types of outlets unique and common the latter type is mainly conditioned by the occurrence of fault blocks acting as connecting media between the aquifers ca chloride brines originating from deep seated and confined reservoirs leak along the major faults and contaminate the relatively fresh groundwaters originating from the regional aquifers during the last two decades the salinity of groundwaters at the outlets of aquifers and in springs discharging into the valleys have increased as the result of overexploitation the changes in the chemical composition of these waters indicated inflow of dilute ca chloride brines which replace at an ever increasing rate the fresh water of the area the inflow of brines is limited to fault zones and seems to be controlled by the counterpressure of the overlying fresh water overexploitation diminishes this counterpressure thus facilitating the progressive upflow of brines

early depositional history of a rift basin miocene in western sinai abstract the cenozoic stratigraphic record in the gulf of suez provides a model of six events for the early sedimentologic history of a rifted basin classic exposures on the east coast of the suez in the western sinai yield a composite section of the miocene succession 1 1 oligocene early miocene nukul formation terrigenous clastics in fluvial fandelta and littoral environments filled local valleys 2 2 during early miocene transgression lower rudies member nearshore and shelf sediments accumulated at a rate no less than 4 cm 1000 yrs rates of accumulation increased dramatically at the beginning of the middle miocene 3 3 during the early part of the middle miocene basinal muds and evaporites upper rudeis member kareem formation and part of belayim formation accumulated at a rate of 106 146 cm 1000 yrs 4 4 rates slowed during short term shoaling periods when shelf carbonates hammam faraun member were deposited 5 5 a fifth event is represented by more than 2 km of late miocene evaporites zeit south gharib formations which accumulated at a minimum rate of 32 cm 1000 yrs 6 6 the post evaporite event of alluvial and shallow deep marine sedimentation began in the pliocene and is continuing today local carbonate buildups developed upon fault blocks during the second and fourth stages evaporite deposition can be a very rapid process in the filling of rifted basins

variations in the surface texture of suspended quartz grains in the loire river an sem study statistical size distribution and scanning electron microscopic studies of suspended sand grains in the loire river at montjean france were carried out over a period of a year hydrological cycle to discern seasonal variations the sand fraction in suspension is better sorted during winter average mean 0 69 mm median 0 65 0 95 mm sorting value 1 1 1 35 and is dominated by quartzo feldspathic minerals during summer on the contrary this fraction is rich in mica minerals and is poorly sorted average mean 1 21 mm median 0 33 0 95 mm sorting value 1 4 2 0 the grain size of the coarser fraction shows a tendency to increase with river discharge up to an optimum discharge of about 1000 m3 s 1 and thereafter decreases scanning electron photomicroscopy of quartz grains from the suspended sand population indicates that both mechanical and chemical features occur the former conchoidal fractures mechanical fractures and breakage dominate in the samples collected near the water surface during winter floods and the latter solution pits vermicular features silica flowers neogene silica and diatoms in the samples from the bottom during low summer flows during summer chemical action takes place on sediments prior to or upon their deposition sediments that are resuspended during winter floods undergo mainly physical processes attrition abrasion mixed surface features are therefore observed during average and low river discharge inheritance of these surface features from the source area is however not completely excluded thus the history of quartz grains in suspension can be reconstructed from sem exoscopic studies therefore it can be proposed that the fluvial quartz grain surface textures result from a combination of alternating chemical and physical processes

imprints in silica grains induced during an open channel flow experiment determination of microtextural signatures during aqueous transport abstract the aim of this work is to identify and characterize microtextural signatures in silica glass grains used as analogous to quartz that are produced during aqueous transport at different flow velocities with variable sediment concentrations transport distances and time intervals to achieve this an open channel flow experiment was conducted with a mixture of sand and silica glass microspheres in varying conditions velocity from 0 67 to 1 4 m s duration 1 or 10 minutes distance 0 to 2 5 m and sediment concentration 60 or 80 experimental conditions were used to replicate natural phenomena such as river superficial velocity or coastal swash processes before the experiment the microsphere surfaces were imaged and clear of any microtextural imprint increasing velocity distance and sediment concentration exhibited a strong correlation with higher numbers of surfaces abundantly covered with microtextures of mechanical origin i e craters abrasion marks and v shaped percussion marks sem microphotographs of silica were analyzed and classified to provide examples of the specific microtextures produced during the open channel flow experiment the purpose of the experiment was to characterize surface microscopic signatures in quartz grains replicating hydrodynamic conditions of coastal and fluvial environments the results demonstrated a strong correlation between higher velocities and higher sediment concentrations and a larger presence of microtextural mechanical imprints in the grains analyzed thus demonstrating a clear relation between microtextural imprints and water flow modes these results have important implications for future microtextural works analyzing grain imprints and their relation to sediment transport types an example demonstrated here is that the higher presence of v marks could be used as an indicator of supercritical flow conditions

origin dimensions and distribution of remobilized carbonate deposits in a tectonically active zone eocene thebes formation sinai egypt abstract determination of the distribution and mechanism for carbonate dominated mass transport sediments is often compromised by the scale and access to exposures consequently many studies lack the resolution to capture the heterogeneity and dimensions of mass transport deposits this study documents the size shape and stratal assemblage of remobilized carbonates in the eocene thebes formation in the hammam faraun fault block hffb of western sinai revealing the complexities of carbonate mass transport deposits at sub seismic scale present day pseudo three dimensional exposure of the thebes formation in a large fault block formed during the opening of the gulf of suez allowed for lateral and down dip measurement of slope and basinal facies in the field and from photos remobilized facies were digitized in the photos and evaluated using image analysis software a technique with a wide range of applications to outcrop studies of sedimentary architecture debris flow deposits in the lower section of the thebes formation comprises clasts with differing fossil assemblages a relative sea level rise at the start of upper thebes formation deposition resulted in basinal sediments comprising periodic incursions of high density turbidite grainstones encased within a background of planktonic foraminiferal wackestones foraminiferal assemblages of remobilized facies imply multiple sources on the carbonate platform demonstrating the effect of short lived tectonism on slope instability and deposition of mass transport deposits the results of the study confirm that tectonism associated with the syrian arc fold belt which altered the style of basin sedimentation between egypt and syria persisted into the eocene at least as far south as wadi araba in the western desert and hammam faraun in sinai in addition the shape size and extent of the two dominant remobilized facies debris flows and grainstone turbidites are influenced by their mud rich versus grainy compositions

carbonate evaporite siliciclastic transitions in quaternary rift sediments of the northwestern red sea abstract the quaternary and recent coastal environments of the egyptian red sea and gulf of suez are characterized by rapid lateral variations carbonates evaporites and siliciclastic sediments exist in close proximity although the climate is exceptionally dry the numerous wadis draining high hinterland relief deliver important quantities of coarse clastics to coastal environments during the rare periods of flash flooding however because this efficient supply is sporadic coastal waters are contaminated for short catastrophic periods which are followed by a rapid return to clear water carbonate sedimentation the warm arid conditions on the other hand favour both carbonate reef production and evaporite mineral precipitation rapid lateral transitions between continental siliciclastic and marine carbonate facies are favoured by a particular morphology closely related to the active distensional tectonic setting within the red sea rift block faulting which began in the early miocene and continues today has resulted in numerous subparallel grabens and horsts situated between the onshore basement relief and the coast the structural depressions grabens tend to trap much of the episodic siliciclastic input favouring permanent carbonate production in the nearby littoral environments

microtextural characteristics of quartz grains transported and deposited by tsunamis and storms article i nfo the complex transport and depositional processes associated with tsunamis and storms and the peculiarities of local inundation present questions associated with the recognition and differentiation of the sedimentary signature of these events this work presents a study of quartz grains transported and deposited by tsunami and storm waves with the objective of identifying specific microtextural signatures caused by high energy marine inundations and to correlate them with their principal sedimentary sources in this empirical study 1150 quartz grains 78 samples and their microtextural signatures were observed analyzed and classified using scanning electron microscope photomicrographs the results suggest that although no specific microtextural signature is associated with high energy inundations there are strong increases in the percent age of fresh surfaces and percussion marks when compared with the potential source material moreover tsunami and storm grains present the greatest microtextural variance among all the grains analyzed never theless specific local conditions and sediment concentrations constrain the microtextural implications on tsunami or storm grains one laboratory experiment was designed to test microtextural implications in grains subjected to variable velocities sediment concentration and time the surface microscopic signature in quartz grains of high energy events further contributes to the development of more efficient sedimentological criteria to identify deposits associated with tsunami and storm events

groundwater flow modeling of two levels perched karstic leaking aquifers as a tool for estimating recharge and hydraulic parameters summary perched springs in nature emerge from aquifers laying on aquitards within the unsaturated zone some of which emerge one above the other a finite element model was introduced using the feflow code for simulating the groundwater flow regime in each of these aquifers for quantifying the fraction of rain that recharges the aquifers and for estimating the hydrogeological parameters of the aquifers and aquitards many of the perched springs in israel are found in the judea group aquifer a stratified carbonate rock unit characterised by a well developed karst system the batir and jamia springs exemplifies such a system where batir is the upper spring discharging at the contact between aminadav and moza formations and jamia is the lower one discharging at the contact between kesalon and sorek formations the 25 year long measured spring s hydrographs were used to calibrate the spring s coefficients the hydraulic conductivities of the different layers the karst features and the yearly amount of rain recharging the spring

architecture and depositional sequences of tertiary fault block carbonate platforms an analysis from outcrop miocene gulf of suez and computer modelling abstract this study combines outcrop with seismic data and tectonostratigraphic modelling to characterise the stratigraphy of tertiary fault block carbonate platforms seismic sections from the middle east and southeast asia indicate that carbonate platforms commonly develop on fault blocks in the late syn rift to post rift stage of basin evolution they are characterised by retrogradational or drowning morphologies with deep water clastics evaporites sealing the platforms a new tectono stratigraphic modelling program simulates the development of carbonate platforms on domino style fault blocks and predicts a distinctive tectonic control on the evolving syn rift stratigraphy detailed field work from a three dimensionally exposed miocene syn rift platform from the gulf of suez gebel abu shaar egypt shows the existence of unconformity bound depositional sequences which are predicted by the program and are interpreted to have formed in response to fault block rotation the sequences are characterised by synchronous hangingwall subsidence and footwall uplift and erosion the seismic images the modelling and the outcrop study provide different levels of information on fault block platforms and their characteristic stratigraphy the scale of the modelling is of particular value as it provides a link between the seismic scale imaging and outcrop data

hydrological and hydrogeochemical methods for the delineation of complex groundwater flow systems as evidenced in the bet shean valley israel abstract the bet shean valley northern israel is the base level of groundwater draining from three regional aquifers in the natural undisturbed state i e at the beginning of the six ties groundwater drained through many springs with widely different chemical composition and with a total discharge of about 135 million m 3 for the efficient utilization of water resources it was decided to recover groundwater from wells at the cost of a considerable reduction of spring discharges since the sequence and the rate of spring decay diverged from the pattern that had been predicted it became necessary to delineate aquifers and their connections to the various springs three groups of methods were employed for this purpose a analysis of discharge characteristics and their relation to source aquifers b methods for the identification of well fields that affect the discharge of a particular spring and c hydrogeochemical methods for the delineation of flow paths the paper presents the relevant data the methods employed and the results that were achieved the utility and the limitations of the various methods were discussed and general guidelines for the delineation of groundwater flow in multi aquifer systems were formulated

rare earths and yttrium hydrostratigraphy along the lake kinneret dead sea arava transform fault israel and adjoining territories rare earth elements and y rey have been analysed in 49 groundwaters from localities in the areas of lake kinneret and the jordan and arava valleys these waters originate from various aquifers and the rey abundances are expected to be controlled by the aquifer rocks the rey pattern allow one to distinguish interaction of waters with basalts basalt limestone interaction zones silicified limestones limestones from the judea and avdat groups upper cretaceous and eocene respectively and sandstones of the lower cretaceous kurnub group groundwater from the quaternary alluvial fill dead sea group are either controlled by judea group limestone or kurnub group sandstone the rey patterns show characteristic features for each group in hydrogeological systems the rocks of natural replenishment areas are usually not the same as rock units from which the waters are collected this becomes evident by comparing the lithostratigraphic groups from which the waters were collected and the hydrochemical grouping according to rey patterns with their characteristic trends and anomalies in many cases there is a correspondence between the lithostratigraphic and the hydrochemical grouping in other cases the 2 groupings disagree this disagreement proves inter aquifer flow of groundwater in some cases the geologically derived aquifers rocks of origin differ from those indicated by rey patterns thus applying the rey grouping new fundamental information for hydrological models can be given and sources of salinisation can be elucidated

miocene evaporites of the red sea rift yemen republic sedimentology of the salif halite abstract miocene evaporites are spectacularly exposed along the red sea coastal plain of yemen especially in the region of salif over one thousand metres of bedded halite containing regular millimetre thick laminae of anhydrite were precipitated below wave base which need not have been very deep in a relatively quiet and protected basin virtually cut off from the open sea of the mediterranean and indian ocean a metre thick unit of laminated and rippled anhydrite within the halite is the result of a major decrease in salinity within the basin gypsum overlying the halite is bedded and laminated but does contain vague vertical structures suggestive of an original selenitic mineralogy this sulphate was probably precipitated as bottom growth gypsum and decanted crystals more open circulation in the basin was established in the early pliocene when carbonate muds and siliciclastics were deposited these miocene evaporites were precipitated during the continental rifting and opening of the red sea gulf of aden when half graben structures were formed and fed by occasional influxes of marine water subsequent sedimentation and tectonic deformation led to major halokinesis the development of diapirs and exposure of the halite along the coastal plain

patterns of reef sedimentation and diagenesis in the miocene of cyprus abstract an early tertiary regressive sedimentary succession developed along an active plate margin in cyprus a varied clastic and carbonate succession of the miocene pakhna formation and then messinian evaporites culminate the regression within the pakhna formation two phases of reef growth were developed the aquitanian burdigalian terra member and the tortonian koronia member the terra member is exposed only in west and southeast cyprus mainly between pelagic carbonates the koronia member is exposed around the margins of the troodos massif in north south and west cyprus and on the akamas peninsula in northwest cyprus there was little tectonic influence on the growth pattern of the terra member reefs the koronia member reefs however are developed on up faulted blocks most of the koronia member fore reef facies and associated clastic input was shed into downfaulted basinal depocentres there are differences between the first and second miocene reef phases in cyprus in primary reef construction and in the level of background carbonate pelagic sedimentation the terra member reefs are dominantly framestones comprising faviids and domal poritids with several types of secondary reef dwelling corals there is no indication of a connection with the indo pacific coral faunal province benthonic foraminifera and fragments of crustose coralline algae are abundant in the off reef by contrast the koronia member is a bindstone comprising virtually monospecific laminar poritid corals but with coralline algae also playing a role in encrustation the koronia member off reef facies comprises decimetre thick beds of bioclastic reef detritus in north cyprus however beds of similar detritus centimetres in thickness are overlain by progressively thicker up to several metres debris flow sheets the terra member reefs have limited acicular fringe cement probably aragonitic this is overlain by an abundant marine bladed formerly high mg calcite cement later cements present in the reef facies include micritised calcite spars perhaps indicating microboring in cements during their precipitation neomorphism was extensive converting most cements to low mg calcite stable isotopic data for all the cyprus calcites exhibit depletion in the heavier isotopes 18 o and 13 c indicative of meteoric alteration the koronia member limestones show abundant indication of early lithification with fringing acicular aragonite and micrite cements stable isotopic data of the botryoidal aragonite cements indicate a marine origin the dolomite is thought to result from marine freshwater mixing and to be of pliocene age on the basis of stratigraphical solution replacement fabric and stable isotopic data sr isotopic data do not contradict a pliocene age dolomite characteristically replaces the pliocene fissure fill contents in southeast cyprus and off reef horizons in the terra member of west cyprus and koronia member of north cyprus the growth and burial history of miocene reefs contribute to the understanding of the tectonic history and palaeogeographical evolution of cyprus

carbonate platform facies models various types of carbonate platforms are characterized by distinctive profiles facies and evolutionary sequences ramps may be homoclinal or distally steepened and may have fringing or barrier shoal water complexes of ooid pellet sands or skeletal banks homoclinal ramps pass seaward into deeper water without major break in slope and lack deep water breccias distally steepened ramps may be low energy and characterized by widespread shallow subwave base mud blankets or high energy with coastal beach dune complexes and widespread skeletal sand blankets slope facies may contain abundant breccias of slope derived clasts rimmed shelves have relatively flat tops and marked break in slopes at the high energy shallow shelf edge where they pass into deep water such shelves may be aggraded with peritidal facies extending over much of the shelf or incipiently drowned depending on magnitude of sea level fluctuations they may be accretionary or bypass types that include gullied slope escarpment and high relief erosional forms intrashelf basins occur on some shelves controlling distribution of reservoir and source beds isolated platforms are surrounded by deeper water and may be located on rifted continental margins or on submarine volcanoes most have high relief rimmed margins platforms that have been subjected to rapid sea level rise may be incipiently drowned and characterized by raised rims elevated patch or pinnacle reefs and widespread subwave base carbonate or fine clastic blankets completely drowned shelves develop where the shelf is submerged to subphotic depths terminating shallow water deposition and commonly resulting in blanketing of the shelf by deeper water facies some margins show extensive down to basin faulting that is contemporaneous with carbonate deposition or associated with thick prograding clastic sequences the various types of platforms change in response to variations in sedimentation subsidence or sea level rise and may form distinctive evolutionary sequences the relatively few models presented appear to accommodate most geological examples some of which contain major reservoir facies

carbonates and relative changes in sea level abstract in the geologic record some of the most accurate gauges of changes in sea level are the sediment type geometry and diagenesis of carbonate shelves and platforms this is because carbonates frequently occur at or very near sea level and are usually less compacted than siliciclastics world wide changes in relative sea level the sum of eustatic sea level changes sedimentation and crustal movements have occurred repeatedly and cyclicly through geologic time producing characteristic responses in carbonates 1 1 relative rises in sea level usually caused by the cumulative effect of tectonic subsidence and eustatic rise may result in the following 1 1 a drowned carbonate reefs or platforms here carbonate growth potential is exceeded by relative sea level rise and is characterized by shallow water sediments overlain by hardgrounds and or deep water sediments some of which may be condensed sequences 1 2 b platforms where only the fast growing rim and patches of the interior are able to match sea level rise while the remainder of the platform is drowned temporarily 1 3 c platforms which keep up and maintain a flat top at sea level and contain shallow water sediments whose thickness at the least matches the height of the sea level rise if terrigenous supply is limited prograding sheets of shelf carbonate occur frequently capped by supratidal evaporites with prograding shelf margin carbonate clinoforms and turbidites if terrigenous supply is high the shelf carbonates encroach on deltaics 2 2 relative drops in sea level caused by crustal uplift or by subsidence being outpaced by a eustatic drop in sea level cause karst and soil development over shelves and platforms deposition of deep water evaporites in adjacent semi enclosed basins and in open marine basins the deposition of deltaic and aeolian clastics that bypassed the shelf falls are accompanied by platform wide fresh water diagenesis during relative sea level rises marine diagenesis is common in the subtidal portions of the shoaling upward carbonates and fresh water diagenesis and dolomitization and sulphate deposition is common in their intertidal and supratidal portions the stratigraphic significance of these reponses to relative sea level change is that many are tied to eustatic events and so are predictable within a basin of deposition

extension and rifting the zeit region gulf of suez abstract a field analysis of faults and fractures in the ras gharib ras gemsa region of the gulf of suez shows that the main late cenozoic extension occurred perpendicular to the rift axis three main types of dip slip normal faults successively developed as the tilt of blocks bounded by antithetic normal faults increased determinations of the amount of extension from structural data are compatible with estimates made using subsidence data through a simplified model of lithospheric stretching the uplift of rift shoulders is related in chronology and volume to the subsidence of the rift the geometry of fault patterns and directions of extension suggests that the late cenozoic total movement corresponds to a counterclockwise rotation of 4 5 of sinai relative to africa with a pole close to cairo

using the cl br ratio as a tracer to identify the origin of salinity in aquifers in spain and portugal summary a study on the applicability of the cl br molar ratio for identifying the origin of groundwater salinity is presented according to the experience gained in spain and portugal cl br ratios in atmospheric bulk deposition have helped to distinguish groundwater in which cl derives only from atmospheric sources from groundwater in which cl is contributed by endogenous lithological or anthropogenic sources considering the seawater cl br ratio of 655 4 cl br ratios may be increased up to 1500 in groundwater by the addition of wastewater loaded with nacl or leaching of solid waste and decreased to 300 by the use of br based pesticides or leaching farm animal or septic waste leaching and dissolution of natural and industrial nacl and of gypsum rich formations containing some nacl may yield cl br ratios between one thousand and several thousand although leaching of potassium halides near salt mines produces cl br ratios below the seawater ratio when cl content in groundwater is not affected by extreme evaporation up to halite saturation at 6 2 mol l 1 of nacl and if there are no other cl sources recharge by rainfall can be estimated by relating cl in atmospheric bulk deposition to derived groundwater the cl br ratio appears to be a good tracer for discriminating non atmospheric cl contributions to groundwater provided chemical analyses are accurate since its variability is not wide data have been collected from different areas of spain and portugal and are explained and illustrated by two cases described in detail the donana aquifer in southwest spain and the canary islands both showing the mixing paths