geologic evolution of the iraqi zagros and its influence on the distribution of hydrocarbons in the kurdistan region whereas the vast majority of discovered hydrocarbon reserves in iraq reside in cretaceous and cenozoic reservoirs numerous oil and gas fields have been discovered recently in deeper jurassic and triassic reservoirs in the kurdistan region of iraq this study presents a middle upper jurassic thermal maturity map for the kurdistan region of iraq and demonstrates that regional first order trends in jurassic source rock maturity show a close correlation to the spatial distribution of oil gravities within the overlying jurassic and cretaceous reservoirs this distribution is consistent with compartmentalization of the active source rock kitchens due to zagros folding resulting in relatively short distance migration and charge of the anticlinal structures from the adjacent synclinal lows the thermal maturity map confirms relatively low maturity over the mosul high where the cretaceous and cenozoic section overlying the source rock interval is relatively thin and increasing maturity to the southeast as the thickness of the cenozoic foredeep sediments increases toward the depocenter located in the southeastern iraqi zagros and the adjacent iranian zagros the correlative trend in oil gravities is exemplified by the recent jurassic discoveries low to medium gravity oils 14 27 api in shaikan and atrush to the northwest light oil 39 47 api in mirawa and bina bawi and gas condensate 55 api in miran west to the southeast understanding thermal maturity patterns and hydrocarbon fluid type distributions will help to guide risk assessment for remaining prospectivity and future exploration drilling within the kurdistan region of iraq

sulphuric acid speleogenesis and landscape evolution montecchio cave albegna river valley southern tuscany italy abstract montecchio cave grosseto province tuscany italy opens at 320 m asl in a small outcrop of jurassic limestone calcare massiccio fm close to the albegna river this area is characterised by the presence of several thermal springs and the outcropping of travertine deposits at different altitudes the montecchio cave with passage length development of over 1700 m is characterised by the presence of several sub horizontal passages and many medium and small scale morphologies indicative of sulphuric acid speleogenesis sas the thermal aquifer is intercepted at a depth of about 100 m below the entrance the water temperature exceeds 30 c and sulphate content is over 1300 mg l 1 the cave hosts large gypsum deposits from 40 to 100 m below the entrance that are by products of the reaction between sulphuric acid and the carbonate host rock the lower part of the cave hosts over 1 m thick calcite cave raft deposits which are evidence of long standing probably thermal water in an evaporative environment related to significant air currents sulphur isotopes of gypsum have negative 34 s values from 28 3 to 24 2 typical of sas calcite cave rafts and speleogenetic gypsum both yield young u th ages varying from 68 5 ka to 2 ka bp indicating a rapid phase of dewatering followed by gypsum precipitation in aerate environment this fast water table lowering is related to a rapid incision of the nearby albegna river and was followed by a 20 30 m fluctuation of the thermal water table as recorded in the calcite raft deposits and gypsum crusts

constrains on the origin and history of the eastern mediterranean basin abstract the basin formed along the northern passive margin of gondwanaland as a relict of the mesozoic neotethys in early mesozoic time though direct information from the basin itself is meagre the geology of its passive margins and the regional framework of the tethys evolution constrain the formation and history of the basin the eastern mediterranean and its passive margins are interpreted to have formed as a result of several faulting and continental breakup phases from early permian to middle jurassic times before pangaea s complete disintegration this led to the detachment of the eratosthenes and tauride blocks from the margins of the levant and herodotus basins respectively the latter merged in the northeast with the cyprus basin that extended along arabia s northern margin the main rifting probably occurred in the triassic leading to seafloor spreading in the herodotus and cyprus basins while along the levant margin important rifting also occurred in the jurassic during the initial rifting stages extension perpendicular to the levant margin was important but subsequently the tauride block drifted mainly northward the existence of the passive margins and slopes of the eastern mediterranean is documented at least from the end of the middle jurassic until then the basin was probably narrow 200 300 km but during the main phase of the africa laurasia separation it grew to twice its present width or more this scenario depends critically on the interpretation that the tauride block was originally located next to northeastern africa on the western side of the eratosthenes block plate convergence and consumption of the northern portion of the basin have taken place since mid cretaceous times but the active convergent boundary on its northern side formed only in the neogene by modification of earlier structures some intra plate deformation also took place especially in the neogene but it hardly changed the original configuration of the remaining portion of the basin

late cretaceous to palaeogene thin skinned tectonics of the palmyrides belt syria abstract detailed mapping in the palmyrides belt syria shows that its structure resulted from thin skinned tectonics and includes duplexes anticlinal stacks and imbricate thrusts in the frontal palmyrides the main decollement level is formed by triassic evaporites but a cenomanian marl interval locally forms a subsidiary decollement ramps linking the two decollement levels generate duplexes formed by thin horses of jurassic and lower cretaceous material to the north in the central palmyrides the decollement ramps down from a triassic to an eocambrian level in which it continues as a main basal decollement the ramp connection between the cambrian and triassic decollement levels is responsible for the anticlinal structure of the central palmyrides bilas block accurate mapping balanced cross sections and forward deformation modelling allowed calculation of the amount of shortening of the sedimentary cover the minimum estimate is 20 km this independent field based result is compatible with previous estimates from a general seismic study of the cenozoic mesozoic series due to the presence of folded neogene deposits the deformation of the palmyrides belt was thought to be miocene pliocene in age however eocene carbonates unconformably overlie various thrust units in the frontal palmyrides reconstruction indicates 15 km of shortening during the late maastrichtian to upper eocene and 5 km of shortening since the late miocene thus the main shortening event of the palmyrides occurred during the palaeocene seismic well and gravity data are used to integrate the shallow structure in a crustal scale deformation model gravity modelling confirms previous interpretations of a relatively flat moho beneath the palmyrides belt and suggests that deformation of the belt resulted from a movement of the sedimentary cover of northern syria 20 km to the south along a 200 km long flat decollement within the eocambrian this syrian decollement between the sedimentary cover and the basement is supposed to root down north of syria within the north arabian plate boundary such a decollement implies four times more shortening in the sedimentary cover than in the palmyrides basement

crustal shortening in the palmyride fold belt syria and implications for movement along the dead sea fault system an edited version of this paper was published in tectonics by the american geophysical union agu copyright 1990 agu see also http www agu org journals tc http atlas geo cornell edu syria chaimov tectonics 1990 html

the structure of the crust and upper mantle in the dead sea rift abstract the previously published results of a deep seismic refraction study of the dead sea gulf of elat rift show crustal thinning underneath the rift and the presence of a 5 km thick velocity transition zone in the lower crust along the rift the structural interpretation of the first arrival data was revised using the detailed velocity depth distribution the revised crustal thicknesses are 35 km near elat and 27 km 160 km south of elat the crustal thinning and the presence of the velocity transition zone are interpreted as being the result of intrusion of upper mantle material into the lower crust possibly representing the initial shape of the processes which have been active further south in the red sea since earlier times

fault reactivation and structural inversion backarc and intraplate compressive deformations example of the eastern sunda shelf indonesia the tectonic evolution of the eastern sunda platform in indonesia is revealed by the study of seismic profiles and comprises three general tectonic periods during the cenozoic extension with graben infill from the paleogene to the early miocene a tectonically quiet period with only broad subsidence and a middle miocene recent period of folding inversion and thrusting these structures reveal changes in the intraplate stress field which was controlled by the changes in the boundary conditions of the plates collisions on the northern and eastern sides and interplate coupling southward along the java subduction zone inversions often occurred without reactivation of pre existing normal fault planes at the upper levels of these faults the factors controlling these deformations are discussed with special interest placed on the conditions for the potential reactivation of cohesionless normal faults inversion and reactivations were mostly controlled by the orientation of the pre existing fault planes in relation with the regional stress field and by the tectonic stress regime in a strike slip regime effective principal stresses 1 and 3 horizontal with 1 2 3 the optimum conditions for reactivation in isotropic rocks are pre existing faults that strike close to the potential two vertical conjugate failure planes the same mechanical properties as for pre existing fault prevail in such conditions strike slip movements and reverse strike slip movements and associated en echelon folds were generally observed in a compressive regime 1 and 2 horizontal with 1 2 3 typical steeply dipping normal faults are difficult to reactivate by slip movements we suggest that reverse slip movements occurred in the deeper levels of faults and were accommodated by flexure above the pre existing fault planes and the inversion of grabens the strongly inverted grabens are those whose orientation is perpendicular to the regional compression nevertheless with strong regional shortening large uplifts and thrust faults were observed with reactivation in the form of reverse or reverse strike slip movements along pre existing steeply dipping normal fault planes

the syrian arc system an overview abstract a comparison between the ne directed negev and palmyra foreland monoclines of the syrian arc shows strong similarity in both their statigraphy and late mesozoic and cenozoic tectonic history a first phase of simple folding in the senonian was followed by a phase of reverse faulting in the miocene and ended with a phase of post miocene uplift in the style of fault bend fold this triple deformation of the north arabian subplate was contemporaneous with the thrusting of the tauros zagros zone the ne sw direction of the syrian arc as well as many other structures on the african and arabian plates are an inherited ancient feature predating any contact with the eurasian plate the continental drift proposed for turkey and arabia is reviewed and rejected for both the amounts of horizontal displacement of the dead sea rift and the east anatolian fault are estimated to be 45 and 27 km respectively it is suggested that the stress system upon the levant has been nw directed since the late cretaceous to the present time the dead sea rift n s stress direction is a local post miocene response to limited regional shift and to intense uplift

downslope migrating large dunes in the chattian carbonate ramp of the majella mountains central apennines italy abstract this work is the result of detailed geological mapping and stratigraphic analysis of the lepidocyclina limestone in the northern sector of the majella mountains central apennines the lepidocyclina limestone represents an informal member of the bolognano formation chattian to messinian in age four main lithofacies have been recognized planar cross bedded grainstone fa moderate angle cross bedded grainstone to packstone fb sigmoidal cross bedded grainstone fc and bioturbated marly packstone to wackestone fd a detailed description of the recognized lithofacies and facies association of the lepidocyclina limestone is given in this work together with an interpretation of the corresponding depositional setting and a discussion of the related larger scale processes in summary the depositional profile of the lepidocyclina limestone is consistent with a carbonate ramp where most of the sediments appear to be parautochthonous in the middle ramp environment and autochthonous dominated in the outer ramp environment palaeocurrent patterns indicate a strong generally north west basin ward direction that affected the middle ramp environment and developed a wide down slope migrating dune field considering that the warm oligocene climate of the mediterranean area was favorable to tropical cyclone development both in terms of frequency and intensity it is suggested that return currents generated by strong winds or storms were common on the lepidocyclina carbonate ramp thus favoring the development of the observed dune field

basement depth and sedimentary velocity structure in the northern arabian platform eastern syria an edited version of this paper was published in geophysical journal international by blackwell publishing blackwell publishing retains the copyright see also http www blackwellpublishing com journal asp ref 0956 540xs http atlas geo cornell edu syria brew gji 1997 htm

plio quaternary uplift rates in the outer zone of the central apennines fold and thrust belt italy abstract geological seismic and borehole data permitted the reconstruction of the plio quaternary uplift subsidence and erosion sedimentation history for the outer sector of the central apennines during the latest contractional stages middle late pliocene the frontal sector of the belt experienced a net subsidence locally compensated by the growth of the fold and thrust system this tectonic uplift was localized at the axial culmination of the anticlines and particularly for the major structures was responsible for exhumation and erosion of the neogene succession and for near flat planation surfaces development on meso cenozoic carbonate rocks at the crest of the anticlines since the early middle pleistocene a regional doming involved the outer part of the belt peri adriatic domain this process interacted with quaternary eustatic sea level fluctuations and caused the basinward migration of shallow marine deposits forming an overall prograding system quaternary shoreline retreat base level drop and climatic changes were mainly associated with valley deepening and fluvial terrace formation the present study outlines that fold thrust growth and regional doming driving processes characterized by different amplitude wavelength and uplift rate amounts are both responsible for the morphological setting of the central apennines external zones

corrosion morphology and cave wall alteration in an alpine sulfuric acid cave kraushohle austria abstract whereas most karstic caves worldwide are formed by carbonic acid a small but significant number of sub surface cavities are the product of sulfuric acid speleogenesis sas in the eastern alps no cave has so far been attributed to this type in this multidisciplinary study we demonstrate that kraushohle in northern styria was indeed formed by sas the cave pattern shows individual chambers 3d mazes and blind galleries as well as typical sas morphologies such as cupolas gypsum replacement pockets corrosion notches and convection niches ceiling pendant drip holes are described here for the first time and these corrosion features are fully consistent with the sas model other features of kraushohle include thick gypsum deposits with strongly depleted 34 s values and other minerals mostly sulfates indicating highly acidic conditions we also studied acid rock interaction processes giving rise to widespread corrosion and concomitant replacement by gypsum petrographic and geochemical analyses reveal the presence of a distinctive alteration layer of highly increased porosity at the interface between the host limestone and the secondary gypsum dissolution and replacement of the limestone was fast enough to prevent the development of c and o isotopic alteration halos but resulted in selective leaching of elements this stable isotope signal is thus different from the pronounced isotope gradient commonly observed in co 2 dominated hypogenic caves petrographic observations reveal that the limestone gypsum replacement was a nearly constant volume process

petroleum prospects of lebanon some remarks from sedimentological and diagenetic studies of jurassic carbonates abstract only seven exploration wells have been drilled in lebanon to date failing to encounter oil or gas in commercial quantities and to penetrate into unexposed pre jurassic reservoirs this paper shows that the sedimentological and diagenetic characteristics of the major lebanese jurassic carbonate rock unit the kesrouane formation thickness 1000 m negate jurassic hydrocarbon prospectivity in northern mount lebanon the jurassic platform in this region was subjected to a first emergence and invasion by meteoric waters in the late jurassic causing a pervasive cementation a second phase of uplift and meteoric flushing occurred in the cenozoic thus only the areas located far from the jurassic and post cretaceous phreatic realms e g offshore tripoli nw lebanon may have been less affected by meteoric diagenesis and still provide promising prospects a 1993 seismic survey offshore tripoli confirmed the presence of late triassic evaporites in northern lebanon this also adds confidence to the results of the nahr ibrahim electrical survey which earlier suggested the presence of these evaporites in the subsurface of central lebanon the pre jurassic sequence hence is sealed and protected from the meteoric invasion observed in the overlying jurassic rocks accordingly the qartaba horst structure central northern lebanon would be equally if not more attractive for a pre jurassic play

the cretaceous paleogene boundary in jordan abstract the cretaceous paleogene k pg boundary in jordan is marked by a major depositional hiatus that differs in magnitude from place to place due to variable structural movements of the syrian arc fold belt that resulted in irregularity of jordan levant depositional basin after the deposition of maastrichtian succession to elucidate the nature of this hiatus fieldwork was carried out at a number of locations including lithofacies and stratigraphic analysis and a multi proxy study of microplanktonic biostratigraphy calcareous nannofossilis and planktonic formaminifera however the duration of this hiatus extended over latest maastrichtian and early danian stages this is based on the absence of the planktonic foraminifera pseudoguembelina hariaensis cf3 pseudoguembelina palpebra cf2 plummerita hantkeninoides cf1 guembelitria cretacea p0 parvularugoglobigerina eugubina p zones and parasubbotina pseudobulloides p1a subzones and the coeval calcareous nannofossils nephrolithus frequens and markalius inversus zones we estimate that in the paleo lows areas an unexpected 3 96 ma hiatus is present conversely in swell areas the duration of the hiatus represents the entire danian selandian interval and revealed an unexpected 10 33 ma hiatus especially in the central part of jordan subsequently a marked transgression took place over the whole of jordan which resulted in the prevalence of deep water conditions zones p4 or equivalent np7 8 this caused the deposition of a retrogradational parasequence set of middle shelf pelagic marl and chalk during a rapid relative rise of sea level a correlative hiatus and time gap have also been reported in different parts of the arabian and african plates indicating that jordan was influenced by regional tectonics that combined with the latest maastrichtian sea level fall resulted in a long term sub marine hiatus and or non deposition of sediments a combination of sea level changes and tectonic uplift are the likely cause for such a long gap in the sediment record in the region

sulfur and oxygen isotopes in the gypsum deposits of the provalata sulfuric acid cave macedonia abstract sulfur stable isotopes from cave sulfates mainly gypsum have been used in a number of studies to trace the source of sulfur in caves formed by sulfuric acid but only few studies apply combined use of sulfur and oxygen stable isotopes to further understand the processes operating in sulfuric acid speleogenesis sas here we present results of a detailed study of the distribution of sulfur and oxygen stable isotopes within the gypsum deposits formed during sulfuric acid speleogenesis of provalata cave macedonia the 18o vs vsmow values range between 3 9 and 8 2 and the 34s vs cdt values between 7 5 and 0 7 we found a strong positive correlation between the 18o and 34s values with a 0 5 increase in the 34s for every 1 increase in the 18o indicating that both oxygen and sulfur isotopes were concurrently affected during the oxidation process we attribute these effects to be either due to environmental control concentrations of h2s and o2 or due to isotope fractionation during multi step microbial oxidation also affected by the environmental conditions additionally a shift of 1 85 in the 34s values prior to the h2s oxidation is found indicating evolution of the h2s 34s in the sas system the wide range of both 18o and 34s values in the gypsum deposits of the small provalata cave show that both the number of samples and their location can be an important factor for the understanding of sulfuric acid speleogenesis using stable isotopes

the oligocene miocene stratigraphic evolution of the majella carbonate platform central apennines italy abstract the stratigraphic architecture of the bolognano formation documents the evolution of the majella carbonate platform in response to global and local changes that affected the mediterranean area during the oligocene miocene interval the bolognano formation consists of a homoclinal ramp that developed in a warm subtropical environment five different lithofacies associations have been identified lepidocyclina calcarenites cherty marly limestones bryozon calcarenites hemipelagic marls and marly limestones and lithothamnion limestones each association corresponds to a single lithostratigraphic unit except for the lepidocyclina calcarenites that form two distinct lithostratigraphic units lepidocyclina calcarenites 1 and 2 these six units reflect alternation of shallow water carbonate production and drowning specifically two of the three stages of shallow water carbonate production regard the development of wide dune fields within the middle ramp one stage dominated by red algae and a sea grass carbonate factory whereas the two drowning phases are represented by marly cherty limestones and calcareous marls a new biostratigraphic framework for bolognano formation is presented based on high resolution analysis of calcareous nannofossil assemblages which proved to be very useful for biostratigraphic constraints also in shallow water settings using this approach we have linked the first drowning phase late chattian aquitanian p p in age to western mediterranean volcanism and the mi 1 event and the second drowning phase late burdigalian serravallian in age to the closure of the indo pacific passage and the occurrence of the global monterey event these results permit a new deciphering in terms of sequence stratigraphy of the bolognano formation that is interpreted as a 2nd order super sequence that can be subdivided into 3 transgressive regressive sequences

deformation around stepovers in strike slip fault zones abstract this stuck addresses the kinematics of stepovers in strike slip fault zones where left lateral faults step rightward or right lateral faults step leftward a stepover is regarded as containing an internal strike slip fault whose ends link to transform faults surrounded by uniformly distributed deformation the kinematics are governed by k the ratio of slip rates on the internal fault and transform faults and gq the angle between these taults the convergence direction across the deformation at angle to the internal fault is an azimuth along which vectors do not rotate around vertical axes the lebanon stopover on the dead sea fault zone and the big bend stepover on the san andreas fault zone provide case studies in lebanon the time averaged deformation since 15 ma involves k 0 06 32 and 34 it accounts for 30 of anticlockwise rotation of cretaceous magnetization vectors in the lebanon mountains and 50 rotation of jurassic vectors the present phase of deformation around the big bend which began at 5 7 ma and imolves k 0 89 20 and 98 has instead only caused small rotations both clockwise and anticlockwise much of this region s structure including the dramatic up to 80 clockwise rotation of magnetization vectors in the transverse ranges is shown to relate instead to an earlier deformation phase with much lower k

crustal structure variations and transcurrent faulting at the eastern and western margins of the eastern mediterranean abstract crustal structure variations within the crust of the eastern mediterranean as well as within the continental crust of the land areas east and west of the basin have caused segmentation of the collision zones which extend from sicily through the calabrian arc the hellenic arc and the cyprian arc to the taurus chain on both sides of the eastern mediterranean in southeastern sicily and in the levant similar tectonic features have developed hinge faults exist along both continental margins due to the different modes of collision between the land areas and the adjacent oceanic areas landward of the margins two large transcurrent fault systems the scicli fault zone and the dead sea rift have developed due to the existence of unique crustal units within the continental crust adjacent to the margins on both sides these units are more buoyant than the adjacent crust and resist underthrusting the initial faulting along both transcurrent fault systems probably started at the collision zone in the north and propagated to the south where large extensional areas the pantelleria rift and the red sea exist

sulfuric acid speleogenesis sas close to the water table examples from southern france austria and sicily caves formed by rising sulfuric waters have been described from all over the world in a wide variety of climate settings from arid regions to mid latitude and alpine areas h2s is generally formed at depth by reduction of sulfates in the presence of hydrocarbons and is transported in solution through the deep aquifers in tectonically disturbed areas major fractures eventually allow these h2s bearing fluids to rise to the surface where oxidation processes can become active producing sulfuric acid this extremely strong acid reacts with the carbonate bedrock creating caves some of which are among the largest and most spectacular in the world production of sulfuric acid mostly occurs at or close to the water table but also in subaerial conditions in moisture films and droplets in the cave environment these caves are generated at or immediately above the water table where condensation corrosion processes are dominant creating a set of characteristic meso and micromorphologies due to their close connection to the base level these caves can also precisely record past hydrological and geomorphological settings certain authigenic cave minerals produced during the sulfuric acid speleogenesis sas phase allow determination of the exact timing of speleogenesis this paper deals with the morphological geochemical and mineralogical description of four very typical sulfuric acid water table caves in europe the grotte du chat in the southern french alps the acqua fitusa cave in sicily italy and the bad deutsch altenburg and kraushohle caves in austria

crustal structure of central syria the intracontinental palmyride mountain belt an edited version of this paper was published in tectonophysics by elsevier science copyright 1992 elsevier science see also http dx doi org 10 1016 0040 1951 92 90395 m http atlas geo cornell edu syria al saad et al 1992 html

when did the northern apennine become a mountain chain abstract the purpose of the present paper is to bracket the age of the initial uplift of the northern apennine chain by means of all the available evidence the collected data show that the age of the lacustrine or fluvio lacustrine units which have aggraded in the intramontane basins is late pliocene in the northwestern tip of the northern apennine and mostly early pleistocene elsewhere the age of the oldest terraced fluvial deposits showing the initiation of incision is mostly middle pleistocene the uplift of the summit areas of low relief most likely took place during the middle pleistocene it is concluded that the uplift occurring during middle and upper pleistocene caused an area of rather low relief to become the northern apennine mountain chain an eastward shift of the uplift through time is likely

iron oxide copper gold mineralization of the devonian laoshankou deposit xinjiang nw china in the central asian orogenic belt abstract the laoshankou iron oxide cu au iocg deposit 41 km southwest of qinghe city xinjiang nw china is the most important magnetite deposit with economic cu and au metal reserve 3 26 mt fe 33 5 36 4 9 8 kt cu 0 2 0 4 and 0 14 t au 0 5 1 3 g t in the east junggar terrane of the central asian orogenic belt caob the deposit is hosted by volcanic rocks of the middle devonian beitashan formation in this study four hypogene hydrothermal alteration stages have been identified including the ca silicate alteration stage i amphibole epidote magnetite alteration mineralization stage ii pyrite chalcopyrite mineralization stage iii and late hydrothermal veining stage iv mineralogical fluid inclusion including laser raman spectroscopy and mineral sulfur oxygen hydrogen and carbon isotope analyses were carried out to elucidate the nature and origin of the hydrothermal fluids at laoshankou stage i hydrothermal fluids were likely derived from a 590 c magmatic fluid with 18 o water 9 2 9 7 subsequently the magnetite epidote amphibole assemblage may have precipitated from the fluids 530 c formed by the mixing of high temperature magmatic fluids with the seawater that reacted with 18 o rich wall rocks the fluid rock reactions are reflected from the 18 o water 9 6 10 7 and d water 25 5 23 8 values the sub economic stage iii a pyrite epidote quartz garnet mineralization likely occurred at 415 c and was formed by fluids with 34 s fluid 3 7 0 5 d water 110 94 and 18 o water 7 92 8 9 the lower temperature and presence of organic matter of the stage iii a fluids may have reflected the involvement of meteoric water and organic matter from the wall rocks the economic cu mineralization stage iii b was probably formed by the mixing of a meteoric water dominated fluid medium temperature low salinity and na dominated and a ca rich formation water in equilibrium with the volcanic wall rocks medium temperature medium salinity and ca fe mg dominated with 34 s fluid 2 6 18 o water 5 6 5 8 13 c water 3 3 3 1 and d water 92 95 towards the end of the fluid evolution meteoric water incursion may have continued and generated the ore barren low temperature low salinity and na dominated fluids although the laoshankou deposit contains distinct skarn alteration the ore mineral assemblage and ore fluid features indicate that it is not a typical skarn deposit but share many similarities with many central andean iocg deposits we conclude that the iocg ore forming setting in the devonian east junggar was analogous to the cretaceous central andes in that they both occurred during basin inversion in a volcanic arc setting

sulfuric acid speleogenesis of carlsbad cavern and its relationship to hydrocarbons delaware basin new mexico and texas sulfur isotope data and ph dependence of the mineral endellite support the hypothesis that carlsbad cavern and other caves in the guadalupe mountains were dissolved primarily by sulfuric acid rather than by carbonic acid floor gypsum deposits up to 10 m thick and native sulfur in the caves are significantly enriched in 32 s isotope 34 s values as low as 25 8 per mil cdt indicate that the cave sulfur and gypsum are the end products of microbial reactions associated with hydrocarbons a model for a genetic connection between hydrocarbons in the basin and caves in the guadalupe mountains is proposed as the guadalupe mountains were uplifted during the late pliocene pleistocene oil and gas moved updip in the basin the gas reacted with sulfate anions derived from dissolution of the castile anhydrite to form h 2 s co 2 and castile limestone the hydrogen sulfide rose into the capitan reef along joints forereef carbonate beds or bell canyon siliciclastic beds and there reacted with oxygenated groundwater to form sulfuric acid and carlsbad cavern a sulfuric acid mode of dissolution may be responsible for large scale porosity of some delaware basin reservoirs and for oil field karst reservoirs in other petroleum basins of the world

sulfuric acid caves of italy a review abstract in italy especially along the apennine chain numerous active and inactive sulfuric acid speleogenetic sas caves have been documented in the last two decades here we present an overview of these peculiar hypogene systems illustrating their main geomorphological and mineralogical features and the microbial signatures observed in the active underground environment sas caves are widely distributed in the northern and central apennines whereas they are less abundant in the southern apennines in the apulian foreland in sicily and in sardinia their location is significantly influenced by lithological and structural rock properties as they occur in carbonate areas where acidic fluids deriving from the interactions with deep seated sulfates and or sulfides rise through deeply rooted geological structures geomorphological observations demonstrated sub horizontal maze passages to be one of the most favorite arrangements for sas caves whereas gypsum sulfur and alunite supergroup minerals are the most typical sulfuric acid by products the 34 s results demonstrated the deep seated h2s sources to be mainly related to the interaction between triassic evaporites and hydrocarbons

occurrence of hypogenic caves in a karst region examples from central italy the caves of the umbria and marche regions in central italy are made up of three dimensional maze systems that display different general morphologies due to the various geological and structural contexts at the same time the internal morphologies of the passages galleries and shafts present some similarity with solutional galleries characterized by cupolas and blind pits anastamotic passages roof pendants and phreatic passages situated at different levels some of these caves are still active as is the case for frassassi gorge parrano gorge and acquasanta terme with galleries that reach the phreatic zone where there is a rising of highly mineralized water rich in hydrosulfydric acid and with erosion of limestone walls and the formation of gypsum elsewhere there are fossil caves such as monte cucco and pozzi della piana where large speleothems of gypsum are present 500 m or more above the regional water table in all of these important karst systems it is possible to recognize basal input points through fracture and intergranular porosity networks at the base of the oxidizing zone in the core of the anticline where mineralized water rises up from the triassic evaporitic layers in small hydrogeological circuits different underground morphologies can derive from the presence of a water table related to an external stream or from the confined setting of the carbonate rocks underlying low permeable sedimentary cover where artesian conditions can occur

the structural relationship between the east anatolian and dead sea fault zones in southeastern turkey abstract the complex structural relationship between the east anatolian and dead sea fault zones is examined mostly based on field observations in southeastern turkey where the two fault zones are close together several faults previously poorly documented can be traced to connect either to the east anatolian fault zone or to the dead sea fault zone one of these faults connects the dead sea fault zone to the east to the amanos fault to the west the amanos fault a n trending normal fault is a part of the east anatolian fault zone since it is apparently a left step fault between the main and southern strands of the east anatolian fault zone the dead sea fault zone also is connected to the east anatolian fault zone northeast of the town of narli and or northeast of the hazar lake therefore we suggest that the two fault zones can be considered as one broad fault system in southeastern turkey although they are well recognized as two different fault zones this fault system is responsible for several complex neogene structural features of the western part of the southeastern turkey one of these is the hatay graben which can be divided into southern central and northern parts the graben contains down to the west normal faults in its southern part the central part of the graben is a divergent strike slip basin and the northern part is a half graben

sulfuric acid speleogenesis in the majella massif abruzzo central apennines italy abstract many active and inactive hypogene sulfuric acid cave systems are known along the apennines italy the cavallone bove cave system is located in the external part of the central apennine chain in the majella massif and opens at 1470 m asl along the taranta gorge south of chieti the presence in these caves of peculiar geomorphological features such as feeders rising channels megacusps cupolas and replacement pockets offers evidence of rising acidic fluids the secondary mineral deposits including meter size white gypsum deposits alunite jarosite black layers of iron manganese oxides and hydroxides along with a rare association of authigenic rutile ilmenite minerals indicate a sulfuric acid origin stable isotope analyses of sulfates further confirm a sulfuric acid speleogenetic sas origin of these minerals and in general of the whole cave system with h2s coming from the bacterial sulfate reduction of deep seated triassic evaporites interacting with hydrocarbons alunite dating demonstrates this water table sas cave to have been active at least until 1 52 0 28 ma all the evidence suggests that cavallone bove is an ancient sulfuric acid karst system that was uplifted

geological evolution of the afro arabian dome abstract the afro arabian dome includes the elevated continental regions enclosing the red sea gulf of aden and the ethiopian rift system and extends northwards as far as jordan it is more than an order of magnitude larger than other african uplifts both the structures and the igneous rocks of the dome appear to be products of the superimposition of two perhaps three semi independent generating systems initiated at different times but all still active a strain pattern dominated by nw trending basins and rifts first became established early in the cretaceous by the end of the oligocene much of the extensional strain had been taken up along the red sea and gulf of aden axes which subsequently developed into an ocean palaeogene trap volcanism of mildly alkaline to transitional character was related to this horizontal extension rather than to doming further west the east sahara swell has a history of intermittent alkaline volcanicity which began in the mesozoic and was independent of magmatism in the afro arabian dome volcanicity specifically related to doming began in the miocene along a n s zone of uplift extending from ethiopia to syria this elongated swell forms the northern termination of the east african system of domes and rifts characterized by episodic vertical uplift but very little extension superimposition of epeirogenic uplift upon structures formed by horizontal extension took place in the neogene volcanicity related to vertical tectonics is mildly alkaline in character whereas transitional and tholeiitic magmas are found along the spreading axes

late miocene deformation kinematics along the nw zagros fold thrust belt kurdistan region of iraq constraints from apatite u th he thermochronometry and balanced cross sections

kinematic consistency between the dead sea fault zone and the neogene and quaternary left lateral faulting in se turkey a revised quantitative kinematic model has been determined for the dead sea fault zone dsfz and the left lateral fault zones in se turkey the relative motions of the african and arabian plates across the dsfz are represented by relative rotation about 31 1 n 26 7 e at 0 40 0 02 ma 1 the northern dsfz in syria and southern turkey is interpreted for the first time as a series of transpressional stepovers along which the left lateral slip rate is substantially less than the rate of relative plate motion because this slip is oblique to the plate motion the slip rate on the east anatolian fault zone eafz is estimated as 8 mm a 1 restoring its observed slip thus requires its age to be 4 ma the previous phase of deformation which involved slip on the malatya ovacik fault zone mofz before the eafz came into being is thus dated to 7 4 ma suggesting initiation of the north anatolian fault zone nafz at 7 ma not 5 ma as previously thought the total left lateral slip on the northern dsfz in southernmost turkey is estimated as at least 65 km partitioned with 45 km on the amanos fault 10 km on the east hatay fault and a further 10 km on the kirkpinar fault farther east much of this slip is inferred to have occurred during the miocene before the modern geometry of this plate boundary zone developed when it first formed the af ar plate boundary was relatively complex it initially reactivated preexisting structures in the palmyra foldbelt in syria and in the gaziantep region of southern turkey which were significantly misaligned relative to the plate motion requiring major components of shortening as well as left lateral slip the transition from this initial rather diffuse geometry to the present localised geometry of the dsfz across western syria occurred within the miocene the predicted rate of relative motion between the stable interiors of the turkish and african plates in the vicinity of their common boundary onshore of iskenderun gulf in southern turkey is estimated as westward at 9 mm a 1 however this promontory of the african plate is itself moving westward relative to the stable interior of this plate at 7 8 mm a 1 the rate of localised left lateral slip on the onshore part of this boundary the ne trending yakapinar goksun fault is thus estimated as only 2 mm a 1 this locality can also be regarded as within the distributed boundary zone between the turkish and arabian plates the estimated relative motion between these plates is at 8 7 mm a 1 towards the ssw partitioned between localised left lateral slip at 2 mm a 1 on the yakapinar goksun fault and at least 1 mm a 1 on the amanos fault and 2 5 mm a 1 on east hatay fault with at most distributed left lateral simple shear at 3 2 mm a 1 across the amanos mountains in between however the combined slip on left lateral faults east of the amanos mountains may be as high as 6 mm a 1 with slip at 1 7 mm a 1 on the amanos fault and at 4 3 mm a 1 on the east hatay fault and any active faults farther east this requires no more than 0 7 mm a 1 of distributed simple shear across the amanos mountains raising the possibility that this component of deformation may in fact be zero this small nonzero estimate possibly indicating a closure error arising from minor errors in predicted values of other relative motion vectors it is proposed that this boundary between the turkish and african plates first developed at the same time as the mofz and nafz but its original geometry involving left lateral slip on the karatas osmaniye fault has since become locked by the presence of relatively strong ophiolitic crust within this fault zone this quantitative kinematic model demonstrates for the first time how it is possible for the left lateral faulting accommodating the nnw sse relative motion between the arabian and african plates in nw syria to dovetail into the left lateral faulting accommodating the wsw ene relative motion between the turkish and arabian plates in se turkey

microbiology and geochemistry in a hydrogen sulphide rich karst environment abstract cueva de villa luz a hypogenic cave in tabasco mexico offers a remarkable opportunity to observe chemotrophic microbial interactions within a karst environment the cave water and atmosphere are both rich in hydrogen sulphide measured h 2 s levels in the cave atmosphere reach 210 ppm and so 2 commonly exceeds 35 ppm these gases plus oxygen from the cave air are absorbed by freshwater that accumulates on cave walls from infiltration and condensation oxidation of sulphur and hydrogen sulphide forms concentrated sulphuric acid drip waters contain mean ph values of 1 4 with minimum values as low as 0 1 the cave is fed by at least 26 groundwater inlets with a combined flow of 200 300 l s inlet waters fall into two categories those with high h 2 s content 300 500 mg l mean p co 2 0 03 0 1 atm and no measurable o 2 and those with less than 0 1 mg l h 2 s mean p co 2 0 02 atm and modest o 2 content up to 4 3 mg l both water types have a similar source as shown by their dissolved solid content however the oxygenated water has been exposed to aerated conditions upstream from the inlets so that original h 2 s has been largely lost due to outgassing and oxidation to sulphate increasing the sulphate concentration by about 4 chemical modelling of the water shows that it can be produced by the dissolution of common sulphate carbonate and chloride minerals redox reactions in the cave appear to be microbially mediated sequence analysis of small subunit 16 s ribosomal rna genes of 19 bacterial clones from microbial colonies associated with water drips revealed that 18 were most similar to three thiobacilli spp a genus that often obtains its energy from the oxidation of sulphur compounds the other clone was most similar to acidimicrobium ferrooxidans a moderately thermophilic mineral sulphide oxidizing bacterium oxidation of hydrogen sulphide to sulphuric acid and hence the cave enlargement is probably enhanced by these bacteria two cave enlarging processes were identified 1 sulphuric acid derived from oxidation of the hydrogen sulphide converts subaerial limestone surfaces to gypsum the gypsum falls into the cave stream and is dissolved 2 strongly acidic droplets form on the gypsum and on microbial filaments dissolving limestone where they drip onto the cave floors the source of the h 2 s in the spring waters has not been positively identified the villahermosa petroleum basin within 50 km to the northwest or the el chichon volcano 50 km to the west may serve as source areas for the rising water depletion of 34 s values 11 7 for sulphur stabilized from h 2 s in the cave atmosphere along with the hydrochemistry of the spring waters favour a basinal source

active faulting in the dead sea rift abstract manifestations of late quaternary and holocene faulting were studied in a 500 km long segment of the dead sea transform rift most prominent are left slip faults whose characteristic physiographic features are recognizable along most of the studied segment where these faults bend or are stepped to the left rhomb shaped grabens or pull aparts are produced forming depressions in the reverse situation compressional features such as pressure ridges domes and folds form positive topographic features such structures are combined on a variety of scales ranging from a few hundred meters long to tens of kilometers normal faults sub parallel to the left slip faults produce a trough like valley along much of the dead sea transform but are most prominent along the margins of the large rhomb grabens e g the dead sea trough they apparently record a small component of transverse extension generally their motion is slow young slip did not occur along some segments during the last few 10 4 y elsewhere throws of 10 20 m at least occurred in this period the dead sea transform is seismically active the instrumental and historic records indicate a seismic slip rate of 0 15 0 35 cm y during the last 1000 1500 y while estimates of the average pliocene pleistocene rate are 0 7 1 0 cm y either much creep takes place or the slip rate varies over periods of a few 10 3 y

seismotectonics of the southern boundary of anatolia eastern mediterranean region subduction collision and arc jumping the pattern of seismicity and fault plane solutions of earthquakes are used to outline the tectonic features of the southern boundary of anatolia in the eastern mediterranean and southeastern turkey the results of this study show that this boundary is composed of two distinct parts one in southeastern turkey and syria is a wide and complex zone of continental collision the other in the levantine basin of the eastern mediterranean is a zone of oceanic subduction in the region of continental collision three zones of seismicity are observed most of the seismic activity in this region follows the bitlis zone and is associated with a zone of thrusting and mountain building this appears to be the zone of most active deformation and plate consumption in the plate boundary region between arabia and turkey a less active zone of seismicity to the north of the bitlis zone is interpreted to have been more active in the past whereas another active zone of seismicity to the south is interpreted to be a zone which may be more active in the future as the main zone of plate consumption jumps to the south in the subduction zone of the eastern mediterranean the depth of the subducted slab and the rate of seismicity generally increase from east to west the zone of present day convergence between africa and turkey in the levantine basin can be best outlined by the northern edge of the mediterranean ridge the subduction zone in this area sequentially jumps to the south as small continental fragments collide with existing zones of subduction deep seismic activity near the gulf of antalya is associated with a detached subducted slab north of the anaximander mountains that is distinctly different from the seismic trend which is associated with present day active subduction the plate boundary between africa and turkey at the center of the levantine basin appears to have shifted to the south of the anaximander mountains and florence rise most of the focal mechanisms of the earthquakes along the entire southern boundary of anatolia indicate that n to nnw thrusting is the dominant mode of seismic deformation the present set of data is inconsistent with a major transform fault in the cyprean arc east of cyprus and in southeastern turkey

lower silurian hot shales in north africa and arabia regional distribution and depositional model abstract lowermost silurian organic rich hot shales are the origin of 80 90 of palaeozoic sourced hydrocarbons in north africa and also played a major role in petroleum generation on the arabian peninsula in most cases the shales were deposited directly above upper ordovician peri glacial sandstones during the initial early silurian transgression that was a result of the melting of the late ordovician icecap deposition of the main organic rich shale unit in the north african arabian region was restricted to the earliest silurian rhuddanian stage acuminatus atavus and probably early cyphus graptolite biozones during this short period 1 2 m y a favourable combination of factors existed which led to the development of exceptionally strong oxygen deficiency in the area in most countries of the study area the post rhuddanian silurian shales are organically lean and have not contributed to petroleum generation the distribution and thickness of the basal silurian hot shales have been mapped in detail for the whole north african region using logs from some 300 exploration wells in libya tunisia algeria and morocco in addition all relevant accessible published and unpublished surface and subsurface data of the lower silurian shales in north africa and arabia have been reviewed including sedimentological biostratigraphic and organic geochemical data the lowermost silurian hot shales of northern gondwana are laterally discontinuous and their distribution and thickness were controlled by the early silurian palaeorelief which was shaped mainly by glacial processes of the late ordovician ice age and by pan african and infracambrian compressional and extensional tectonism the thickest and areally most extensive basal silurian organic rich shales in north africa occur in algeria tunisia and western libya while on the arabian peninsula they are most prolific in saudi arabia oman jordan and iraq the hot shales were not deposited in egypt which was a large palaeohigh at that time the depositional model presented may help in better understanding the source potential of the basal silurian shales in less explored regions of north africa and arabia including morocco northern niger and the kufra basin in southeast libya

senonian basin inversion and rejuvenation of rifting in africa and arabia synthesis and implications to plate scale tectonics abstract the late paleozoic to tertiary stratigraphic record of much of the african plate reflects the effects of continental rifting and passive margin development several short lived but widespread and tectonically important compressional or wrench dominated events occurred however during the permian to recent evolution of africa we focus here on the best documented of these events which occurred during the late santonian at that time older sedimentary basins mostly ene wsw trending were folded and inverted including some basins along the tethyan margin from morocco to the syrian arc and the intraplate benue southern chad basins and the lugh mandera basin in oman ophiolites were obducted following the santonian tectonism an extensive phase of rifting occurred in central and north africa and northern arabia spanning from campanian to maastrichtian or paleocene times rejuvenation or acceleration of subsidence occurred in several basins located along the tethyan margin along the atlantic and indian ocean margins as well as within the intraplate domain rifting was sometimes accompanied by magmatic activity especially in offshore northern libya and along the indian ocean margin compressional deformations rejuvenated or developed by latest maastrichtian times along the tethyan margin and locally within the intraplate domain one of the most remarkable attributes of the santonian tectonic event which we consider representative of the major trans african stress field changes is the rapidity with which the change was reflected stratigraphically across north and central africa and its short duration the cause of the santonian compressional event is directly linked to the change in poles of rotation for the opening of the atlantic at 83 85 ma the end of the cretaceous normal magnetic quiet zone this was also synchronous with the obduction of ophiolites along the northeast margin of arabia oman the onset of separation between india and madagascar with formation of the mascarene oceanic basin and the development of the european alpine chain we interpret these phenomena as causally related aspects of a global tectonic event the santonian compressional event as well as the campanian maastrichtian rifting event and the end cretaceous compressional event illustrate the critical connection between intraplate tectonic histories and processes occurring at sometimes very distant plate boundaries

tomographic imaging of lg and sn propagation in the middle east observations based on relatively limited data recorded by sparsely distributed stations have indicated that regional seismic phase propagation lg and sn is very complex in the middle east accurate characterization of regional seismic wave propagation in this region necessitates the use of a large number of seismic stations we have compiled a large data set of regional and local seismograms recorded in the middle east this data set comprises approximately four years of data from national short period networks in turkey and syria data from temporary broadband arrays in saudi arabia and the caspian sea region and data from gsn mednet and geofon stations in the middle east we have used this data set to decipher the character and pattern of regional seismic wave propagation we have mapped zones of blockage as well as inefficient and efficient propagation for lg pg and sn throughout the middle east two tomographic techniques have been developed in order to objectively determine regions of lithospheric attenuation in the middle east we observe evidence of major increase in lg attenuation relative to pg across the bitlis suture and the zagros fold and thrust belt corresponding to the boundary between the arabian and eurasian plates we also observe a zone of inefficient sn propagation along the dead sea fault system which coincides with low pn velocities along most of the dead sea fault system and with previous observations of poor sn propagation in western jordan our observations indicate that in the northern portion of the arabian plate south of the bitlis suture there is also a zone of inefficient sn propagation that would not have been predicted from prior measurements of relatively low pn velocities mapped high attenuation of sn correlates well with regions of cenozoic and holocene basaltic volcanism these regions of uppermost mantle shear wave attenuation most probably have anomously hot and possibly thin lithosphere

a review of the tectonics of the northern middle east region the structure of the northern part of the arabian platform is reviewed in the light of hitherto unpublished exploration data and the presently accepted kinematic model of plate motion in the region the palmyra and sinjar zones share a common history of development involving two stages of rifting one in the triassic jurassic and the other during late cretaceous to early tertiary times deformation of the palmyra zone during the mio pliocene is attributed to north south compression on the eastern block of the dead sea transcurrent system which occurred after continental collision in the north in southeast turkey the asymmetry of the palmyra zone is believed to result from northward underthrusting along the southern boundary facilitated by the presence of shallow triassic evaporites an important nw se cross plate shear zone has been identified which can be traced for 600 km and which controls the course of the river euphrates over long distances in syria and iraq transcurrent motion along this zone resulted in the formation of narrow grabens during the late cretaceous which were compressed during the mio pliocene to a large extent present day structures in the region result from compressional reactivation of old lineaments within the arabian plate by the transcurrent motion of the dead sea fault zone and subsequent continental collision

sulfuric acid caves in calabria south italy cave morphology and sulfate deposits abstract research on karst in the calabria region recognized three different hypogenic cave systems all related to sulfidic thermal springs cave morphology the depositional setting and isotopic characteristics of gypsum deposits reveal that the main process for cave formation was the oxidation of h2s to sulfuric acid this process known as sulfuric acid speleogenesis was induced by thermal water rising towards the oxidizing zone in tectonic windows where dolomitic or limestone rocks outcrop the 34s values of most gypsum deposits prove they originated from sulfuric acid produced by h2s oxidation in the cave atmospheres most gypsum deposits in the calabrian caves in fact exhibit 34s values very similar to those of h2s not to those of sulfate in the groundwater on the contrary the barite and part of the gypsum in the terme luigiane have 34s values similar to those for sulfate in the water implying that the sulfate minerals precipitated in a subaqueous environment a large scale deposition of replacement gypsum occurred only in the water table caves of cassano where subaerial corrosion greatly influenced cave morphology and the typical passage cross sections in the terme luigiane and mount sellaro cave systems these subaerial processes caused only minor changes in inclined passages that had evolved mainly in subaqueous conditions

some outstanding issues in the geology of lebanon and their importance in the tectonic evolution of the levantine region abstract the concept of pervasive and disruptive late neogene quaternary strike slip tectonics in lebanon has made establishing a satisfactory pre neogene palaeogeographic and palaeotectonic history for the area difficult research has allowed clarification of three fundamental issues that permit the setting of lebanon against its adjacent regions to be more firmly assigned the first issue is the identification of the significance of the 100 km long nne ssw trending monocline of the western lebanon flexure this feature is interpreted as a modified and rejuvenated early mesozoic hinge line that is presumed to be the northern continuation of the carmel sinai hinge line to the south the second issue is the correlation of the mount lebanon bekaa and anti lebanon complex with the adjacent intracontinental palmyride fold belt of syria through recognition in each of common divisions in structural style between a higher northern zone dominated by broadly spaced box folds and a lower southern zone with more numerous closely spaced and more internally complex folds the third issue involves the identification of major two stage late cretaceous to palaeogene syrian arc tectonism within lebanon resolution of these issues suggests a tectonic model for the region whereby the levantine region formed in two main phases the first of these was the multiphase late palaeozoic early mesozoic rifting of the area which imposed a fundamental extensional fabric over much of the region the second tectonic phase was the subsequent inversion of these extensional structures in the two stage syrian arc deformation of senonian and late palaeogene age which gave rise to the main lebanon structures it is this syrian arc tectonism rather than the late cenozoic strike slip that was probably the main structuring agent which affected the lebanon area the transpression from the braided dead sea fault motion although locally complex is an essentially neotectonic overprint on an already existing fabric offset of syrian arc structures in lebanon suggests that the total sinistral motion of the yammouneh fault segment of the dead sea fault is around 47 km

reflux stratabound dolostone and hydrothermal volcanism associated dolostone a two stage dolomitization model jurassic lebanon the kesrouane formation which is characterized by pervasive dolomitization has a stratigraphic thickness that exceeds 1000 m it is part of a broad carbonate platform deposited in the levant region and represents 60 of the lebanese jurassic rocks two genetically distinct dolostones are recognized within this unit 1 fine to medium crystalline non planar grey dolostone and 2 coarse crystalline planar beige dolostone the former is stratabound and of early jurassic age 87 sr 86 sr 0ae707455 this dolostone locally exhibits pseudomorphs of evaporite nodules pointing towards seepage reflux dolomitization by hypersaline to marine related fluids exposures of the coarse crystalline dolostone are associated with regional pre cretaceous faults along which late jurassic volcanics also occur sedimentological and diagenetic considerations coupled with microthermometry support a hydrothermal origin for this dolostone with th values of primary inclusions between 50 and 80 c the related dolomitizing fluids are mesosaline 3ae5 12ae0 eq wt nacl and are believed to result from the mixing of evaporative brines and sea water dolomitization is thus believed to have occurred in two stages whereby fluids invaded the host rocks first by seepage reflux explaining the resulting early jurassic stratabound dolostone and later through fracture flow along the faults associated with the late jurassic volcanism explaining the coarse crystalline hydrothemal dolostone

dynamic equilibrium among erosion river incision and coastal uplift in the northern and central apennines italy erosion river incision and uplift rates in the northern and central apennines italy since 0 9 ma are determined from new cosmogenic nuclide data beryllium 10 concentrations in modern and middle pleistocene sediments indicate erosion rates from 0 20 to 0 58 mm yr these rates are similar to estimates of sediment yield 0 12 0 44 mm yr river incision 0 35 mm yr and uplift 0 01 1 0 mm yr rates inferred from other methods that integrate landscape process rates since the early pleistocene these rates of landscape change are significantly lower than long term exhumation rates of 1 2 mm yr since ca 4 5 ma inferred from thermochronometry collectively these data suggest that hillslope erosion and river incision rates in the northern and central apennines have balanced local uplift rates for 1 my but that exhumation rates have slowed significantly since emergence of the mountain chain in the pliocene this condition of dynamic equilibrium was potentially achieved within ca 3 ma similar to some model predictions of hillslope and fluvial system adjustment

structure of the earth s crust in jordan from potential field data abstract gravity and magnetic data were collected and used to study the crustal structure of jordan three new geophysical maps of jordan were created a moho discontinuity map a crystalline basement surface map and a map showing the lowest limit of magnetic blocks depths of the curie isotherm were also calculated results indicate that the depth to the moho discontinuity in jordan varies from 32 to 33 km in the northwest to 38 km in the southeast the basement complex rocks outcrop on the surface in the southwest but lie at about 8 km in the northeast the curie isotherm 585 c lies at a depth of about 10 km in the area east of the dead sea and dips southeastward towards the al sirhan wadi sirhan southeast jordan where it is located at 35 km depth local isostasy of rock masses blocks in jordan does not occur nevertheless this does not rule out the possible existence of isostasy in a regional scale at greater depths within the mantle

iron and aluminum hydroxysulfates from acid sulfate waters acid sulfate waters are produced mostly by the oxidation of common sulfide minerals such as pyrite chalcopyrite pyrrhotite and marcasite in rocks soils sediments and industrial wastes this spontaneous process of mineral weathering plays a fundamental role in the supergene alteration of ore deposits the formation of acid sulfate soils and the mobilization and release of acidity and metals to surface and ground waters the purely natural process of acid rock drainage is often intensified by human activities related to mining mineral processing construction soil drainage and dredging geochemical reaction rates are accelerated because physical disturbance gives greater exposure of mineral surfaces to air and water and to microbes that catalyze the reaction process large quantities of reactive sulfides are also concentrated and exposed to air as a result of mining and mineral processing acid sulfate waters produce a number of fairly insoluble hydroxysulfate and oxyhydroxide minerals that precipitate during oxidation hydrolysis and neutralization the objective of this chapter is to describe the formation properties fate and environmental implications of the nano to microphase hydroxy sulfates of fe and al that are precipitated from acid sulfate waters these minerals are commonly of poor crystallinity and difficult to characterize much remains to be learned about their occurrence formation and properties mine drainage the best known examples of acid sulfate waters are those released from mines where coal and metallic sulfide ores have been exploited ash et al 1951 barton 1978 nordstrom 1982a rose and cravotta 1998 nordstrom and alpers 1999 there may be as many as 500 000 inactive or abandoned mine sites in the united states alone lyon et al 1993 although most of these pose no immediate water quality problem kleinmann 1989 estimated that about 19 300 km of streams and more than 72 000 ha of lakes and reservoirs have been

constraints on arabian plate motion and extensional history of the red sea analysis of the geologic and geophysical data from the western and northern margin of the arabian plate combined with data from the red sea gulf of aden leads to an interpretation of arabian plate motion that supports an episodic extensional history in the red sea and gulf of aden phase 1 extension began in medial to late eocene and was caused by the nw propagation of the reoriented central indian ridge spreading center it stretched and thinned continental crust along numerous wrench and normal faults that reactivated preexisting structures first phase extension stopped when the arabian plate terminally sutured to eurasia in the medial miocene and halted northward movement of arabia relative to africa the combined african arabian plates moved north more slowly constricting and thickening continental crust in the bitlis zagros sutures while the red sea remained technically quiescent and accumulated salt by the early pliocene continued northward movement was accommodated by lateral extrusion of large continental wedges north of the bitlis zagros sutures this allowed arabia to move northward faster than africa and reopen the red sea where phase 2 extension was expressed by seafloor spreading extension within the red sea gulf of aden rift system has been controlled by the interactions and effects of two factors 1 convergent processes between the north margin of the arabian plate and the eurasian plate to the north and 2 northwest propagation of extension associated with the medial eocene reorganization of the central indian spreading center

the epicontinental subsiding margin of the triassic in northern israel north arabian plate abstract the triassic sedimentary pattern of the north arabian margin represents a transition from continental to deep marine we here present a transect part of this suite from southern to northern israel cuttings from the ramalla s and devora n boreholes were studied by petrographic and cathodoluminescence microscopy biotic and sedimentological components were grouped into microfacies upon which a carbonate evaporitic depositional facies model was based mid to inner ramp conditions persisted along the transect essentially following a s n depositional strike with outer ramp to basinal facies to the west five low order lo cycles were identified and integrated into a sequence stratigraphic model with eustatic tectonic and differential subsidence components lo cycle 1 is late anisian pelsonian cycle 2 is late anisian to longobardian cycle 3 is early carnian cycle 4 is late carnian and cycle 5 is at the carnian norian transition facies range from supratidal via lagoonal facies in late hst or lst to calcarenitic shoals and short term deepening to offshore at maximum flooding cycles 1 and 2 are non evaporitic with a clastic influx event in cycle 2 cycles 3 and 4 contain sabkha or salina evaporites in the lagoonal facies that end in the lower part of cycle 5 these facies group into a higher order cyclicity with discrete events that can be correlated between the boreholes depositional and burial history were correlated to alpine and arabian plate stratigraphy over 20 myr from the anisian pelsonian to the norian siliciclastic carbonate and evaporite dominated environments indicate climates ranging from relatively humid to extremely arid rapid subsidence in the late anisian is attributed to neotethyan rifting of northeastern gondwana from latest anisian to early carnian reduced subsidence took place in the face of eustatic sea level rise renewed subsidence in the carnian is attributed to further neotethyan rifting subsidence terminated in the norian with uplift to the north attributed to pre volcanic doming

continental margin evolution of the northern arabian platform in syria copyright aapg 1993 reprinted by permission of the aapg whose permission is required for further use see also http atlas geo cornell edu syria best 1993 html

effect of basement tectonics on hydrocarbon generation migration and accumulation in northern iraq 1 stratigraphic geophysical and remote sensing evidence shows that the basement of northern iraq is fragmented at various scales two large blocks have been recognized the northern mosul block south of the east west to west northwest east southeast trending taurus suture zone and the kirkuk block southwest of the northwest southeast trending zagros suture zone these blocks are in turn subdivided into smaller longitudinal blocks relative to the fold trends the mosul block was less stable and more uplifted relative to the kirkuk block and therefore its stratigraphic record is characterized by wider and more extensive erosion and or periods of nondeposition this led to a relatively poor development of the middle jurassic upper cretaceous potential source rocks ove the mosul block the difference in hydrocarbon resources between the mosul and kirkuk blocks is apparent from the estimated reserves of oil and gas in each development of grabens or half grabens enhanced the already favorable stratigraphic circumstances for the deposition and preservation of potential source rocks in the kirkuk block and locally improved the otherwise inhibiting environment in the mosul block these features show significant difference in their plan shape and relative arrangement in the two blocks in addition within each of the large blocks the synorogenic differential movement on longitudinal basement faults fault stacking had a great effect on hydrocarbon generation migration and entrapment the difference in basement tectonics between the mosul and kirkuk blocks reflects a regional difference in the afro arabian plate margin history along the taurus and zagros belts

tectonic evolution of the ne palmyride mountain belt syria the bishri crustal block investigation of the bishri block centrally positioned amid the diverse tectonic and structural zones of syria reveals details of the intraplate phanerozoic development of the northern arabian platform the bishri block is a broad ne plunging inverted basin located at the ne portion of the palmyride mountain belt where the mountains intersect the euphrates fault system well and seismic data show that subsidence and sedimentation in the bishri area was generally continuous from carboniferous to paleocene time with the bishri block part of the extensive palmyride sinjar trough major bounding faults and a rift type environment are documented in the permo triassic jurassic and cretaceous the present bishri structural and topographic high has been formed through transpressive structural inversion since the mid miocene high angle mesozoic bounding normal faults now have net reverse offsets with a significant dextral strike slip component east of the bishri block towards the euphrates fault system nnw sse striking normal faults exhibit less reverse movement this deformation history correlates with the opening and closing of the nearby neotethys ocean that has driven the evolution of intracontinental syria

cyrenaican shock absorber and associated inversion strain shadow in the collision zone of northeast africa far field compressional stresses resulting from arc collisions with the northeast coast of africa arabia propagated across the african plate in the santonian ca 84 ma and later similar pulses occurred through much of the cenozoic waves of inversion related features including folds thrusts and igneous activity developed during the compressional events structures generated were uneven in intensity and distribution and were commonly concentrated in existing rifts because of the irregular shapes of the north african continental margin and associated inboard basins cyrenaica underwent the most severe shortening although deformation extended eastward from libya to the levant areas south and southeast of cyrenaica the sirt basin and the far western desert of egypt underwent very little shortening because they occupied a regional strain shadow the eastern region of the western desert and sinai which were not sheltered by the stress absorbing cyrenaica inversion recorded strong compressional deformation synchronous with that in cyrenaica as closure of the mediterranean continues cyrenaica will become an indenter comparable to those of other orogenic belts the detailed tectonic evolution of individual northeast african basins has depended on their positions in relation to the cyrenaican strain shadow no single subsidence and paleostress history reflects the complete regional development of the converging mediterranean north african margin

upper crustal velocity structure and basement morphology beneath the intracontinental palmyride fold thrust belt and north arabian platform in syria an edited version of this paper was published in geophysical journal international by blackwell publishing copyright 1993 blackwell publishing see also http www blackwellpublishing com journal asp ref 0956 540xs http atlas geo cornell edu syria seber gji 1993 htm

the maras triple junction southern turkey based on digital elevation model and satellite imagery interpretation this paper describes major structures in the area of the triple junction of the african anatolian and arabian plates near maras southern turkey a review of the literature on the paleogeographic evolution since mid cretaceous time leads to the idea of the southern tethys mesogea persisting between anatolia and africa arabia until middle late miocene consequently collision may have started later and northward subducting lithosphere may still exist under anatolia the dead sea fault may have initiated near the first collision between the anatolian continent and the western corner of the african arabian continent at which point it may have propagated southward a digital elevation model spot and landsat mss images and field work suggest relief js mainly related to finite deformation resulting from on going collision that began at around 13 ma the images show that the east anatolian fault does not crosscut the central taurus belt field data argue that this belt is a left lateral oblique slip fault zone the southern contact of anatolia passes north of the amanos range continental par t of the african plate and connects with the misis range to the southwest the adana low plain may be regarded as a basin formed at a releasing bend the karasu fault zone which belongs to the dead sea fault zone seems to be transpressive and in this case the karasu basin is not a graben north of the amanos range the giirun arc is thrust to the north and may be considered the result of local collision of the uplifting amanos range into anatolia the maras triple junction is accompanied by deformations affecting all plates at the regional scale

the interaction of extensional and contractional deformations in the outer zones of the central apennines italy abstract the relationships among normal faults and thrusts in the apennines of italy are often unclear and the local absence of syn tectonic stratigraphic controls have led to contrasting interpretations on the relative chronology for both classes of structures the activity of normal faults has been variously regarded as due to pre syn or post orogenic extension and the contrasting evidence from different sites has produced an ongoing debate on the normal fault thrust interaction the results of a kinematic analysis on selected composite structures of the outer zones of the central apennines make it possible to unequivocally establish a relative chronology of extensional and contractional deformations detailed mapping outcrop scale observations and structural overprinting relationships support a positive inversion tectonic history where normal faults and fault controlled escarpments formed first and were later deformed by thrusts and related folds all normal faults control the distribution of foredeep deposits thus indicating that the recognised episode of positive inversion is related to the incipient stages of construction of the apennine thrust belt the systematic collection of structural data may help to unravel the evolution of adjacent sectors of the apennine chain as well as of other belt foredeep foreland systems whose extension contraction relationships are poorly constrained

field geometry petrography and geochemistry of a dolomitization front late jurassic central lebanon this contribution describes the field geometry petrography and geochemistry of a well exposed dolomitization front in upper jurassic carbonates and attempts to highlight the sedimentological structural and relative sea level controls on multiphase dolomitization and related diagenetic events the data presented reflect the superposition of various diagenetic phases which have resulted in a single dolostone body whose dimensions are well defined in the field local microbial intraclastic dolomites of late tithonian age accumulated in a hypersaline lagoon during relative sea level fall these pre date beige hydrothermal dolostones 51 to 55 mol caco3 18o 9 3 to 4 0 v pdb 13c 1 5 to 2 1 v pdb 87sr 86sr 0 70742 matrix porosity 6 klinkenberg permeability 0 5 md whose dolomitizing fluid circulated along faults and invaded the nearby facies first the burrows were dolomitized then the bulk rocks resulting in the investigated tongue shaped dolomite body upon late jurassic early cretaceous uplift near surface water percolated through and altered the underlying beige dolostones this event was followed by a ferroan dolomite cement phase which occurred during further burial this contribution featuring a well defined geometric pattern of a dolomitization front with a large petrographic and geochemical data set may also serve as a case study illustrating the complexity of superimposed diagenetic processes which have to be taken into account in modelling exercises of multiphase hydrothermal dolomitization

geological and geomorphological evidence for the southwestern extension of the east anatolian fault zone turkey abstract the left lateral strike slip east anatolian fault zone eafz is the main structural link between the north anatolian fault zone nafz in north and subduction in the mediterranean sea and the transform dead sea fault zone dsfz in south we studied the southwestern continuation of the eafz using combined field investigations including geomorphology geology and paleoseismology mapping of offset drainages lineaments shutter ridges and fault planes in young geological units suggests existence of active faults between the mediterranean coast and turkoglu where it intersects with the dsfz yumurtalik and toprakkale faults are the main tectonic structures and detailed examination of geological and geomorphological evidences suggest their quaternary activity paleoseismic trenching on these faults provided evidence for at least two surface rupturing events in the last 9 000 yr detailed examination of paleo valleys of the ceyhan river suggests that the course of the river migrated due to the activity of the toprakkale fault obtained geological and geomorphological data indicates that the eafz continues across the amanos mountains and the slip transfer is mainly accommodated by the toprakkale and yumurtalik faults

structural geometry and evolution of the dead sea jordan rift system as deduced from new subsurface data abstract analysis of deep drilling data and seismic reflection surveys obtained in recent years permit establishment of a tectonic model of the dead sea jordan rift system that is in part conformable with some of the many often controversial theories on this subject but which also introduces new information negating some concepts that are widely accepted in the literature the dead sea jordan rift system is not a tensional graben between two parallel sets of faults but instead can be best defined as a sinistral transform connecting an incipient oceanic ridge the red sea with an upthrusted collision zone the taurus range the shear is caused by the opening of the red sea and the motion of the arabian sub plate away from the african plate the shearing occurs along a largely south north trending slightly arcuate une consisting of a series of en echelon left stepping left lateral strike slip master faults of varying lengths these faults characteristically die out to the north by bending outward northeast and the movement is taken up by the strike slip faults to the left i e to the west where overlap of the two faults occurs very narrow and very deep grabens have evolved in places the width being equal to the depth the narrowness of these grabens is dictated by the closeness of the overlapping segments of the successive strike slip faults this feature points to the probability that the en echelon strike slip faults have a common root zone at great depth these grabens are not typical leaky pull aparts in that they have no gravimetric magnetic or heat flow anomalies nor are they closed on all four sides by large faults their northern ends are characterized by gradually rising graben floors without major diagonal cross faults the dead sea jordan rift system sensu stricto extends over a distance of 420 km from the northern shore of the gulf of elat to the northern margin of the hula valley southward it is connected with the red sea along the gulf of elat transition zone which has elements of strike slip as well as tensional opening a northern transition zone exists between the hula valley and the taurus arc where diminishing strike slip movement is compensated by several underthrust belts the time of the beginning of the movement along the rift can be established as pre middle miocene because mid miocene sediments overlie an upper cretaceous graben floor rifting has continued intermittently to the present volcanism in the northern fifth of the rift is genetically associated with the seismically active tensional golan hauran jebel drouz wadi sirhan tectonic trend which has a north west southeast orientation and not with the north south trending dead sea jordan rift

structure and evolution of the petroliferous euphrates graben system southeast syria the northwest trending euphrates graben system is an aborted intracontinental rift of late cretaceous age that has subsequently been hidden by cenozoic burial approximately 100 km wide the system comprises an extensive network of grabens and half grabens extending some 160 km from the anah graben in western iraq to the palmyride fold belt in central syria where it becomes more subdued the youngest prerift rocks are presently at a maximum depth of about 5 km based primarily on interpretation of 1500 km of seismic reflection profiles and data from 35 wells we mapped a complex network of numerous branching normal and strike slip faults generally striking northwest and west northwest both branched and single strand linear normal faults of generally steep dip as well as positive and negative flower structures are manifest on seismic sections no single rift bounding fault is observed instead a major flexure coupled with minor normal faulting marks the southwestern edge of the basin with considerable variation along strike to the northeast deformation diminishes on the rawda high near the iraqi border the euphrates graben system likely formed in a transtensional regime with active rifting primarily restricted to the senonian and with an estimated maximum extension of about 6 km minor cenozoic inversion of some structures also is evident approximately 30 oil fields have been discovered in the euphrates graben system since 1984 recoverable reserves discovered to date reportedly exceed 1 billion barrels of oil and lesser amounts of gas light oil is primarily found in lower cretaceous sandstone reservoirs juxtaposed by normal faulting against upper cretaceous synrift sources and seals

morphotectonic study of the lower sangro river valley abruzzi central italy abstract this work analyses the morphotectonic setting of the adriatic piedmont of central italy in order to outline the role of tectonics in the development of the fluvial landscape in this area particularly it focuses on the sangro river which flows in the southern abruzzi from the apennines through the piedmont to the adriatic coast the piedmont area developed in a marine environment from the pliocene to the early pleistocene resulting in the deposition of a clayey sandy sequence afterwards regional uplift processes with ne tilting led to the deposition of a regressive conglomeratic sequence as the area evolved into a continental environment this work is based on the qualitative and quantitative study of drainage patterns and on the analysis and correlation of selected morphological evidence of tectonics on fluvial terraces in order to define the role of tectonics in the geomorphological evolution of the lower sangro river valley the drainage network and its statistical azimuthal distributions are analysed the distribution and the transverse and longitudinal profiles of fluvial terraces are investigated and the morphological evidence for tectonics is then assessed river bends linear valleys beheaded and hanging valleys counterflow confluences of streams space and time correlation of these features allows us to highlight the effects of regional uplift tilting and local tectonics on drainage development following the emergence of the piedmont area middle pleistocene uplift and tilting determined a sw ne consequent and parallel drainage progressive incision shaped the sangro valley as a consequent valley local tectonics along nnw sse and wnw ese faults and fractures resulted in the incision of linear valleys beheading the previous sw ne drainage and controlled the development of a rectangular drainage network late middle pleistocene the drainage network was then rearranged by selective erosion processes maintaining a strong inheritance from of its middle pleistocene configuration

displaced terranes and crustal evolution of the levant and the eastern mediterranean geophysical data from the levant and the eastern mediterranean suggest that this area can be divided into distinct crustal units of different origins for example a marked difference in crustal structure and structural style exists in the levant between samaria and judea south of the carmel structure and the galilee and lebanon north of it on the other hand several microcontinental fragments such as cyprus and the eratosthenes and anaximander seamounts are embedded within the oceanic crust of the eastern mediterranean the present location of these units has resulted from complex tectonic processes which were active during the mid paleozoic mesozoic evolution of this area during this period several crustal units were accreted to the northern margin of africa while others were detached away from it the crustal evolution of the eastern mediterranean and the levant is intimately linked with the closure of the paleo tethys the formation of the neo tethys and its subsequent closure

topographic expression of active faults in the foothills of the northern apennines abstract active faults that rupture the earth s surface leave an imprint on the topography that is recognized using a combination of geomorphic and geologic metrics including triangular facets the shape of mountain fronts the drainage network and incised river valleys with inset terraces we document the presence of a network of active high angle extensional faults collectively embedded in the actively shortening mountain front of the northern apennines that possess unique geomorphic expressions we measure the strain rate for these structures and find that they have a constant throw to length ratio we demonstrate the necessary and sufficient conditions for triangular facet development in the footwalls of these faults and argue that rock type exerts the strongest control the slip rates of these faults range from 0 1 to 0 3 mm yr which is similar to the average rate of river incision and mountain front unroofing determined by corollary studies the faults are a near surface manifestation of deeper crustal processes that are actively uplifting rocks and growing topography at a rate commensurate with surface processes that are eroding the mountain front to base level

speleogenesis of the world s longest cave in hybrid arenites krem puri meghalaya india abstract meghalaya nw india is one of the regions in the world with highest recorded rainfalls because of these peculiar climatic conditions and intense solutional weathering karstic caves are widely reported in the numerous limestone areas of this part of india likewise the extremely high rainfall and the tropical monsoon climate have fostered the formation of several caves in silicate rich lithologies the most important of these caves is krem puri over 25 5 km long characterized by a fracture controlled labyrinth forming a bi dimensional maze with mostly phreatic morphologies and some recent still active vadose entrenchments a detailed petrographic study of the host rocks has shown this cave to be formed along a set of quartzarenite hybrid arenite and calcarenite layers in a mostly siliciclastic sedimentary succession xrf elemental analysis of the different rock strata guiding the speleogenesis confirms that the early stage of cave development is confined mainly in the calcium carbonate rich layers geochemical analyses carried out on water flowing in the cave drips streams have shown that carbonate dissolution is the dominant chemical weathering process contributing to krem puri water solutes whereas the dissolution of quartz feldspars and clays play only a secondary role in rock weathering the morphology of the cave points to a lithology guided dissolution of the carbonate rich layers and piping of the residual quartz sand in phreatic conditions when the surface river network was not yet evolved and the water table was at the level of or higher than the cave this phreatic speleogenetic phase predates the start of river network entrenchment that started not earlier 5 ma ago and probably accelerated around 3 5 ma which deactivated the karst maze with a low denudation rate of 0 15 mm yr this active phreatic cave level which currently lies beneath a more or less 120 m overburden was originally covered by a sedimentary sequence at least 1 2 km thick after its decoupling from the underground drainage system denudation slowly brought the surface close to the maze system gradually introducing infiltration of vadose waters into the conduits this caused the formation of the vadose entrenchments probably