geology and structure of the continental margin off northern israel and the adjacent part of the levantine basin abstract the continental margin off northern israel and southern lebanon is characterized by a narrow coastal plain in places it is absent a narrow shelf a narrow slope which is incised by numerous submarine canyons and by a complex topography of the adjacent deep sea levantine platform detailed seismic reflection surveys have revealed the development of the area since the late miocene during the messinian when the level of the mediterranean sea dropped the present continental slope area was exposed eroded and covered by thinly scattered sediments in the deep basin evaporite bearing series accumulated reaching 1 km in thickness about 60 km offshore during the pliocene quaternary the area was covered by a fine clastic sequence up to 1 5 km thick that forms the present continental margin basinward gravitational slumping of these sediments over the messinian evaporites which acted as a lubricant resulted in a complex topography and many shore parallel rootless growth faults along the base of the continental slope and the adjacent deep sea young faults which are exposed in northern israel and extend seaward comprise the most important structural feature of the study area these faults were active during the pliocene and quaternary possibly also during the miocene the major nw trending young yagur carmel fault and e w trending rosh hanniqra fault extend to the base of the continental slope where they converge enclosing the complex western galilee graben the relief of the base of the pliocene quaternary sequence was affected by motions of these faults and of smaller faults inside the graben farther seaward a horst like block is developed along the extension of the carmel fault still farther basinward there is a group of diapiric ridges trending nw to e w they were formed by flowage of messinian evaporites in some cases these ridges seem to be aligned along underlying faults this group of diapirs is unique in the area the diapir ridges are interpreted as expressions of deeply rooted faults

structural evolution of the latakia ridge and cyprus basin at the front of the cyprus arc eastern mediterranean sea abstract the active deformation front between the african and anatolian plates in the eastern mediterranean is delineated by the cyprus arc present plate kinematic vectors and earthquake data suggest that the movement along the eastern extent of the cyprus arc is largely sinistral strike slip it is however widely accepted that subduction took place beneath cyprus until the early miocene subduction has since thought to have become impeded by the collision of the eratosthenes seamount with the island of cyprus the deformation front of the cyprus arc is dominated by the latakia ridge a steep narrow high which merges gradually with the lower slope of the broad hecataeus rise in the west and extends to the northern levantine coast in the east where the expression of the ridge changes to a number of narrow northeast trending ridges and basins the latakia ridge has previously been interpreted as either a thrust culmination or a positive flower structure this study uses high resolution marine seismic reflection profiles to delineate the stratigraphic and structural architecture of the deformation front from seismic profiles four stratigraphic units bounded by major basin wide unconformities can be identified these units are eocene lower miocene miocene uppermost miocene messinian and pliocene quaternary the timing of deformation determined from growth stratal architectures on the flanks of the major structures show that two main phases of deformation characterize the structural history of the deformation front each of these phases represents a different kinematic regime a compressional regime dominated during the miocene whereas a strike slip regime dominated in the pliocene quaternary

salt tectonics off northern israel the messinian evaporites in the eastern mediterranean represent a world class site to study thin skinned salt tectonic processes like gravity gliding or gravity spreading in contrast to the mesozoic evaporites in the atlantic the related structures are just slightly overprinted by additional tectonic events new high resolution reflection seismic data image for the first time the entire lateral succession of gravity gliding related features as they were suggested by analog models and demonstrate therewith the validity of those models for the messinian evaporites all three regimes of extension translation and compression are present within the range of the seismic profiles however additional observations lead to an adapted and improved model the generation of a critical slope angle caused by subsidence of the levantine basin is considered to be the main driving force for the thin skinned salt tectonics and the lateral basinward creep of the basinal messinian evaporites in the extensional section beneath or near to the continental slope where the basinal evaporites have been withdrawn listric and antithetic listric growth faults rollovers and keystone grabens form asymmetric turtleback structures above salt welds and salt rollers further basinwards an area with little or no deformation of the evaporites defines the translational segment in the compressional region the lower and thickest part of the evaporites show ductile deformation buckle folds and the upper evaporites reveal brittle deformation reverse faults and pop up structures here the basinal evaporites have a maximum thickness of about 1500 m the extensional zone shows continuous synsedimentary tectonic activity until recent times whereas the compressional structures have developed later in a rather sudden event there is clear evidence for neotectonics off the israeli coast which is not related to salt dynamics faults cut through the entire pile of evaporites and the post messinian overburden where the faults pierce the sea floor mud escape structures have been observed deep rooted faults have been interpreted at the base of the messinian paleo slope suggesting a shear zone off israel and parallel to the dead sea transform

controls on the basinwide architecture of late miocene messinian evaporites on the levant margin eastern mediterranean abstract interpretation of 2d and 3d seismic data from the levant margin eastern mediterranean has revealed the complex depositional and structural setting of the basinwide late miocene messinian evaporites the data set covers a total area of 20 000 km2 permitting a semi regional investigation of the thick up to 1 8 km evaporitic wedge the sequential analysis of time structure maps isochron maps and seismic cross sections highlighted the main morphological and structural features characterizing the pre syn and post evaporitic levant margin this approach provided insights on the impact of local vs regional factors in governing the distribution of the messinian salinity crisis in the region two regional features have been recognized as the most significant controlling factors for the architecture of the messinian evaporites firstly a series of anticlines of the syrian arc foldbelt acted as a structural barrier indirectly governing the overall landward extension of the evaporites secondly submarine canyons active in the area at least since the oligocene afiq el arish and ashdod canyons represented preferential sites of erosion and deposition of evaporites our results document therefore the importance of the deep seated structures and relict drainage for the architecture of the messinian evaporites on the levant margin the new insights provided can be additionally used to infer the original depositional geometry of the evaporites in the study area and as an analogue in other mediterranean areas where 3d seismic is not available yet and sub salt imaging is limited

palaeogene and neogene cold seep communities in barbados trinidad and venezuela an overview palaeogene and neogene fossiliferous carbonates from barbados trinidad and northern venezuela are interpreted to have formed at ancient cold seep sites the hydrocarbon seepage that fuelled these chemosymbiotic ecosystems was related to tectonic activity in the southern caribbean region particularly the subduction of the caribbean plate beneath the north atlantic plate the carbonates and fossils from the scotland district north eastern barbados are eocene miocene in age and are associated with two distinct tectonic units the sub oceanic fault zone and a diapiric melange the sub oceanic fault zone is the tectonic junction between accretionary prism sediments and over lying thrust sheets of fore arc basin sediments the loading of the thrust sheets caused methane rich fluids to be expelled from the accretionary prism sediments and channelled to the sea floor via the sub oceanic fault zone where it supported chemosymbiotic invertebrate communities containing vesicomyid lucinid thyasirid solemyid and nuculanid bivalves a variety of gastropods and possibly vestimentiferan tube worms the diapiric melange is considered to represent sediment that failed under pressure in the accretionary prism and was remobilised as a diapir that extruded onto the sea floor providing a conduit for methane and other hydrocarbons that sustained a chemosynthesis based community of vesicomyid lucinid and nuculanid bivalves and various gastropods the geological setting of fossiliferous carbonates known as freeman s bay limestone in southwest trinidad has been less fully investigated the freeman s bay limestone is a member of the miocene lengua formation which is believed to have formed in a fore deep basin on lapping onto an accretionary prism formed by the subduction of proto caribbean crust beneath the south american plate the carbonates and fossils of the fbl including the bivalves pleurophopsis unioides van winkle 1919 and thyasira adoccasa van winkle 1919 lucinids nuculanids and bathymodiolins and provannid and other gastropods are interpreted to have formed at palaeo seep sites on the accretionary prism little is currently known about the geological setting of the fossils collected from the miocene huso member of the pozon formation from northern venezuela but a seep origin is strongly suspected based on the taxa present like the fossil assemblages from barbados and trinidad the venezuelan material is dominated by vesicomyid bivalves together with lucinid thyasirid bathymodiolin and solemyid bivalves and various gastropods these taxa are characteristics of modern cold seep communities most comparisons between the fossil caribbean and modern seep fauna are necessarily at the generic or family level although in some cases individual species are found at both ancient and modern seep sites for example the gastropod cataegis meroglypta is found in seep carbonate from the sofz of barbados and the fbl of trinidad as well as at modern seeps on the barbados prism at the generic level this study has revealed the first fossil occurrences of abyssochrysos and provanna in the caribbean such temporal and spatial links further the understanding of both local and global patterns of biogeographic distribution of cold seep fauna

late jurassic early cretaceous hydrocarbon seep boulders from novaya zemlya and their faunas the paper describes late jurassic early cretaceous seep carbonate boulders from the russian arctic island of novaya zemlya collected in 1875 by a e nordenskiold during his expedition to siberia the carbonates are significantly depleted in heavy carbon isotopes 13c values as low as ca 40 and show textures typical for carbonates formed under the influence of hydrocarbons such as fibrous carbonate cements and corrosion cavities the rocks contain index fossils of late oxfordian early kimmeridgian late tithonian jurassic and latest berriasian early valanginian cretaceous age the fossil fauna is species rich and dominated by molluscs with subordinate brachiopods echinoderms foraminifera serpulids and ostracods most of the species including two chemosymbiotic bivalve species likely belong to the background fauna only a species of a hokkaidoconchid gastropod and a possible abyssochrysoid gastropod can be interpreted as restricted to the seep environment other seep faunas with similar taxonomic structure are suggestive of rather shallow water settings but in case of novaya zemlya seep faunas such structure might result also from high northern latitude

structural analogy between the piano key faults of deep water lebanon and the extensional faults of the canyonlands grabens utah united states the levant basin is a deep water basin in the eastern mediterranean region a large part of the basin contains a characteristic set of closely spaced normal faults informally called the piano key faults these normal faults trending nw se have a fairly high frequency map view spacing of approximately 3 4 km on average and tens to hundreds of meters of interpreted throw a large part of the pre messinian sedimentary strata is faulted including the entire miocene to oligocene sequence at depth all the faults consistently die out at the same intra eocene detachment level this stratigraphic level is interpreted to have a regionally developed shale sequence acting as the basal detachment surface for the piano key faults the amount of throw on the individual faults appears to decrease toward the basin margin and the faults do not extend into the adjacent basins of the broader eastern mediterranean area

the structural evolution of the messinian evaporites in the levantine basin abstract the levantine basin in the south eastern mediterranean sea is a world class site for studying the initial stages of salt tectonics driven by differential sediment load because the messinian evaporites are comparatively young the sediment load varies along the basin margin they are hardly tectonically overprinted and the geometry of the basin and the overburden is well defined in this study we analyse depositional phases of the evaporites and their structural evolution by means of high resolution multi channel seismic data the basinal evaporites have a maximum thickness of about 2 km precipitated during the messinian salinity crisis 5 3 5 9 ma ago the evaporite body is characterized by 5 transparent layers sequenced by four internal reflections we suggest that each of the internal reflection bands indicate a change of evaporite facies possibly interbedded clastic sediments which were deposited during temporal sea level rises all of these internal reflections are differently folded and distorted proving that the deformation was syn depositional thrust angles up to 14 are observed backstripping of the pliocene quaternary reveals that salt tectonic is mainly driven by the sediment load of the nile cone the direction of lateral salt displacement is mainly ssw nne and parallel to the bathymetric trend apparent rollback anticlines off israel result rather from differential subsidence than from lateral salt displacement in the south eastern basin margin the deposition of the isreali slump complex isc is coeval with the onset of salt tectonic faulting suggesting a causal link between slumping processes and salt tectonics the superposition of thin skinned tectonics and thick skinned tectonics becomes apparent in several locations the fold belt off the israeli mediterranean slope mainly results from active strike slip tectonics which becomes evident in faults which reach from the seafloor well below the base of the evaporites owing to the wrenching of the crustal segments which are bounded by deep rooted fault lines like the damietta latakia pelusium and shelf edge hinge line the setting is transpressional south of 32 n where the fault lines bend further towards the west this adds a component of thick skinned transpression to the generally thin skinned compressional regime in the basin above 1 5 km of evaporites a mud volcano is observed with the mud source seemingly within the evaporite layer at the eastern cyprus arc the convergence zone of the african and the anatolian plates deep rooted compression heavily deformed the base of the evaporites whereas at the eratosthenes seamount mainly superficial compression affecting the post messinian sediments and the top of the evaporites is observed

the nile deep sea fan an example of interacting sedimentation salt tectonics and inherited subsalt paleotopographic features abstract structural analysis of the nile deep sea fan ndsf indicates that post miocene deformation is largely controlled by down slope movement above a messinian salt layer in contrast to other similar systems the ndsf shows significant lateral asymmetry and three distinct provinces can be recognized regional variations in salt thickness and base salt geometry within the system have led to the presence of structures typical of both gravity gliding and gravity spreading trends of structures within the western and central parts of the ndsf are consistent with forming due to gravity gliding processes this pattern contrasts with that in the eastern ndsf that seem to be much more consistent with deformation due to gravity spreading observed differences in structural style across the ndsf can be related directly to the paleomorphological evolution of the nile cone during messinian time which is perhaps partly related to features that have been inherited from early mesozoic evolution of the north egypt passive margin in the east part of the ndsf the structural evolution has been significantly influenced by the proximity of eratosthenes seamount this large topographic buttress has served to both limit and deflect northeastward allochthonous advance of the messinian evaporites and has thus severely complicated deformation of the overlying plio quaternary sedimentary cover within the broad corridor that runs nnw sse and cuts obliquely across the modern bathymetry of the nile cone

evolution of the last koninckinids athyridida koninckinidae a precursor signal of the early toarcian mass extinction event in the western tethys abstract koninckinids are a suitable group to shed light on the biotic crisis suffered by brachiopod fauna in the early jurassic koninckinid fauna recorded in the late pliensbachian early toarcian from the easternmost subbetic basin is analyzed and identified as a precursor signal for one of the most conspicuous mass extinction events of the phylum brachiopoda a multi phased interval with episodes of changing environmental conditions whose onset can be detected from the elisa mirabile subzones up to the early toarcian extinction boundary in the lowermost serpentinum zone t oae the koninckinid fauna had a previously well established migration pattern from the intra tethyan to the nw european basins but a first phase with a progressive warming episode in the pliensbachian toarcian transition triggered a koninckinid fauna exodus from the eastern central tethys toward the westernmost mediterranean margins a second stage shows an adaptive response to more adverse conditions in the westernmost tethyan margins and finally an escape and extinction phase is detected in the atlantic areas from the mid polymorphum zone onwards up to their global extinction in the lowermost serpentinum zone this migration pattern is independent of the paleogeographic bioprovinciality and is unrelated to a facies controlled pattern the anoxic suboxic environmental conditions should only be considered as a minor factor of partial control since well oxygenated habitats are noted in the intra tethyan basins and this factor is noticeable only in the second westward migratory stage with dwarf taxa and oligotypical assemblages the analysis of cold seep proxies in the subbetic deposits suggests a radiation that is independent of methane releases in the subbetic basin

paleocene methane seep and wood fall marine environments from spitsbergen svalbard abstract here we describe a paleocene aged methane seep locality and an associated layer of sunken wood from fossildalen on spitsbergen svalbard hosted in offshore to prodelta siltstones of the basilika formation van mijenfjorden group the fossiliferous seep carbonates were first identified in museum collections from expeditions in the 1920s and 1970s and subsequently sampled as ex situ blocks in the field in 2015 the isotopically light composition 13c values approaching 50 v pdb and characteristic petrographic textures of the carbonates combined with the isotopically light archaeal lipids are consistent with their formation at fossil hydrocarbon seep environment the invertebrate fauna within the carbonates is of moderate diversity 17 species and has a shallow water affinity wood specimens within the carbonates contain the borings and shells of wood boring bivalves the seep fauna is dominated by a species of the thyasirid genus conchocele common to other seeps of similar age the data shed new light onto the history of methane seepage on svalbard and the evolution and ecology of seep and wood fall faunas during the latest cretaceous earliest paleogene time interval

a new lower cretaceous hydrocarbon seep locality from the czech carpathians and its fauna abstract a new lower cretaceous hydrocarbon seep locality at baska in the czech carpathians is described the seep carbonate and associated mollusk fauna have been encountered in deep water claystones and siltstones of the upper barremian upper part of the hradist formation associated with pillow lavas of so called teschenite association the investigated carbonate displays petrographic characters typical of seep sediments clotted micrite isopachous rim cements and layered pyrite aggregations the carbon isotopic composition 20 0 to 23 5 vs v pdb most likely indicates anaerobic oxidation of thermogenic methane the fossils recovered from this locality are rather poorly preserved but hokkaidoconchid gastropods and lucinid bivalves in association with trochid and zygopleurid gastropods are identified this finding confirms the existence of seep faunas in the western carpathians which was anticipated based on the presence of seep mollusks and brachiopods in old monographs that cover lower cretaceous fossils of this region the fossils illustrated in the monograph of ascher 1906 are here briefly re evaluated and possible seep members are indicated

methane seep brachiopod fauna within turbidites of the sinaia formation eastern carpathian mountains romania abstract this study elucidates the paleoecology and paleobiogeography of the early cretaceous brachiopod peregrinella known in museum collections from a few localities in romania supplemented with new material from a rediscovered locality first mentioned in the 1870s most peregrinella fossils are enclosed in mass waste deposits but at two sites authigenic limestones with assemblages of brachiopods preserved in life position have been recognized paleontological petrographic stable isotopic and organic geochemical investigations of these brachiopod bearing limestones from the upper sinaia formation eastern carpathian mountains romania confirm peregrinella as having lived at methane seeps in a siliciclastic dominated flysch basin the seeps developed on the slope of the external dacides basin the new collections of peregrinella indicate that shells derived from contemporaneous intrabasin methane seeps and were transported downslope by turbidity currents previous paleoecological models that consider peregrinella to be solely derived from transport downslope from shelf environments are questionable especially as peregrinella has never been recovered from typical shelf faunas in the instance documented here from the external dacides basin methane seep faunas with peregrinella are likely to be the origin of such allochthonous faunas the sinaia formation was deposited in a deep water marine basin derived from an intracontinental rift that developed during late jurassic early cretaceous extension the fractured and faulted basin margin provided the backdrop for the development of the methane seepage and the associated fauna foraminifera from background sediments in the sequence with turbidites confirm a late hauterivian to early barremian age for peregrinella within the sinaia formation this is significant because it indicates that peregrinella ranged through into the barremian whereas it has typically been considered to range only as high as the hauterivian

intense salt deformation in the levant basin in the middle of the messinian salinity crisis abstract while numerous studies have shown that salt related deformation in the levant basin began in the late pliocene or early pleistocene here we show that the first salt related deformation event occurred 3 4 myr earlier in the middle of the messinian salinity crisis considering that the entire crisis lasted only about 650 kyr and that halite deposition in the deep basin may have lasted only 50 kyr this deformation event must have been very short at some point after deposition of nearly half of the evaporitic sequence the upper 200 m thick clastic rich layer glided downdip and formed a series of steep contractional ridges on the deep basin floor however unlike the recent salt motion which is derived from northwestward tilting of the levant continental margin towards the cyprus arc and by basinward progradation of the nile derived overburden the short intra messinian deformation event is enigmatic it predates the nile derived overburden and its direction does not match northwestward tilting we postulate that it may reflect the uplift of the carmel block northeast of the study area and possibly the entire north levant coast in a wider view intra messinian deformation is a circum mediterranean phenomenon possibly reflecting reorganization of the africa eurasia boundary

multiple origins of methane in the earth methane occurrences in the earth s crust are predominantly of biogenic origin i e their ultimate source is biologically formed organic matter methane can also form through inorganic reactions and is consequently termed abiogenic biogenic methanes can either form through bacterial or thermogenic processes bacterial processes follow a co2 reduction and or fermentation pathway the fermentation processes are quantitatively more important in recent fresh sediments and swamps methane formed by co2 reduction however is most common in older sediments and commercial gasfields temperature organic substrate and age may be the major factors controlling the relative importance of the two pathways stable isotope concentrations in thermogenic methanes seem to be controlled by the extent of conversion of organic matter the timing of gas expulsion and trapping the different character of methane in individual sedimentary basins may be a result of the geologic history geothermal methanes are most likely derived from pyrolysis of organic matter abiogenic methane occurs in hydrothermal vents and ophiolite complexes inorganic reactions either surficial or deep seated are the likely source of such methanes a uniform mantle origin of methane is not supported by the observed isotope variations in naturally occurring methanes

taphonomy and palaeoecology of deep water chemosymbiotic bivalves from the eocene of outer eastern carpathians ukraine abstract the paper reports rare occurrence of deep water solemyid and lucinid bivalves from cenozoic sequences of outer eastern carpathians ukraine the studied bivalves occur in the eocene pasichna formation represented by deep water marls and pelagic limestones intercalated with thin bedded calcareous sandstones yielding material re deposited from shallow water this find offered a chance to study the unaltered shell breakage pattern of these deep burrowing solemyid bivalves buried in situ by turbidites the breakage includes arcuate breaks representing likely syn vivo damage related to active burrowing of the animal while telescopic breaks are most likely post mortem distortions produced by the load of the heavy sediment covering sea bottom after a turbiditic event taxonomic study indicates that both solemyid and lucinid bivalves from the eocene of the pasichna formation are most similar to deep water members of their respective clades known from roughly coeval deposits from the tethys the available evidence indicates that bivalves in question lived on the deep sea muddy bottom influenced by turbidite deposits and were buried by them syn vivo or early post mortem this is in contrast to the great majority of molluskan faunas from the carpathian paleogene reworked during transport downbasin from shallow marine settings by mass gravity flows the detailed study of the occurrence mode of deep water bivalves in the carpathian part of the tethys during the paleogene influenced by frequent build up of oxygen depleted waters offers implications for the evolutionary histories of both groups in question for both solemyids and lucinids adaptations to oxygen depleted environments are primordial and are carried from the silurian until today as supported by the presented fossil and actualistic evidence this is in contrast to their histories in high redox potential environments with solemyids known from cold seeps from the devonian onwards and lucinid seep record only from the jurassic onwards

fault controlled evaporite deformation in the levant basin eastern mediterranean abstract during the messinian salinity crisis a multi layered salt giant of 1 5 km thickness was precipitated in the levant basin easternmost mediterranean sea incipient deformation of this geologically young salt layer was commonly explained by gravity driven processes only based on high quality depth migrated seismic data we show for the first time how sub salt extensional faults influence the internal deformation pattern of the messinian evaporites in the levant basin extensional faulting started in the middle miocene and lasted until late messinian times we suggest faulting to have caused the development of fault propagation folds within the evaporite unit subsequently folds may have accommodated tectonic shortening at the latakia ridge and evolved into the presently observed complex intra evaporite fold pattern while fault controlled evaporite deformation is evident in the northern part of the levant basin only evaporites are increasingly influenced by nile derived differential sediment loading towards the south locally zones of reduced amplitudes in the sub salt domain terminate into phase reversed bright spots within the lower part of the evaporites indicating active fluid migration and potentially evaporite dissolution finally we present a high resolution velocity model of the messinian evaporites based on model based processing and residual moveout analysis relatively high interval velocities of acoustically transparent evaporites 3850 4240 km s are consistent with halite whereas lower velocities of reflective layers 3650 4030 km s may point towards the presence of low velocity evaporite facies like gypsum

flexural response of a continental margin to sedimentary loading and lithospheric rupturing the mountain ridge between the levant basin and the dead sea transform during the past 37 myr the levant basin subsided under a 6 km sedimentary section while the adjacent area israel s mountainous backbone judea hills emerged to an elevation of 1 km above sea level what was the flexural contribution of offshore loading to the inland uplift that was also affected at that time by widespread geodynamic heating and uplifting this question becomes particularly challenging considering that in the middle of this period the lithosphere adjacent to the basin 100 200 km east ruptured and a new plate boundary was formed along the dead sea transform dst how did this influence the strength of the lithosphere and how did it change the shape of the flexure we model the flexure caused by offshore sedimentary loading in two phases the pre dst phase applies a flexural solution for an elastic plate without lithospheric rupturing infinite boundaries the post dst phase applies a flexural solution of an elastic plate with a free edge set to resemble a lithosphere with no friction and free to move vertically the apparently unrealistic free edge simplification for a plate boundary provides an upper limit for the uplift it is shown that before the initiation of the dst the flexural effect of the offshore loading on the inland region was negligible and thus most of the observed inland uplift should be explained in terms of deep seated tectonic processes on the contrary the last phase of uplift postdating the formation of the dst was influenced by flexural loading offshore that was intensified near the plate edge

the internal geometry of salt structures a first look using 3d seismic data from the zechstein of the netherlands abstract we present a first look at the large scale complexly folded and faulted internal structure of zechstein salt bodies in nw europe using 3d reflection seismic reflection data from two surveys on the groningen high and the cleaver bank high we focus on a relatively brittle folded and boudinaged claystone carbonate anhydrite layer the z3 stringer enclosed in ductile salt a first classification of the structures is presented and compared with observations from salt mines and analogue and numerical models z3 stringers not only are reservoirs for hydrocarbons but can also present a serious drilling problem in some areas results of this study could provide the basis for better prediction of zones of drilling problems more generally the techniques presented here can be used to predict the internal structure of salt bodies to estimate the geometry of economic deposits of all kinds and locate zones suitable for storage caverns structures observed include an extensive network of zones with increased thickness of the stringer these we infer to have formed by early diagenesis karstification gravitational sliding and associated local sedimentation later this template was deformed into large scale folds and boudins during salt tectonics salt flow was rarely plane strain producing complex fold and boudin geometries deformation was further complicated by the stronger zones of increased thickness which led to strongly non cylindrical structures we present some indications that the thicker zones also influence the locations of later suprasalt structures suggesting a feedback between the early internal evolution of this salt giant and later salt tectonics this study opens the possibility to study the internal structure of the zechstein and other salt giants in 3d using this technique exposing a previously poorly known structure which is comparable in size and complexity to the internal parts of some orogens

tectono stratigraphic evolution of the northern levant basin offshore lebanon abstract seismic interpretation constrained by a detailed assessment of the levant paleogeography allowed subdividing the sedimentary infill of the northern levant basin offshore lebanon in eight major seismic packages fifteen seismic facies have been identified with distinctive characteristics the levant basin architecture is pre determined by a late paleozoic early mesozoic rift that led to the formation of a passive margin dominant aggrading carbonate platforms are observed along the levant margin and deepwater mixed settings i e carbonates and siliciclastics are suggested to prevail in the basin the collision of afro arabia with eurasia led to the development of a flexural basin in the northernmost offshore lebanon since the late cretaceous a southward migration of this flexural depocenter in the miocene is hindered by the change in the stress field along the latakia ridge and by the westward escape of the anatolian plate in late miocene and pliocene times interplay between major geodynamic events as well as sea level fluctuations in the mesozoic and cenozoic induced important marginal uplifts and emersion sediments sourced from the erosion of nubian siliciclastic material and from the exposed granitic red sea rift shoulders and arabian shield were driven into the levant basin the sediment sources diversity the mechanisms of sediment transport through varied pathways i e the levant margin canyons the latakia region and the nile delta deep sea cone are expected to strongly impact the reservoir characteristics and prospectivity of the northern levant basin

late cretaceous maastrichtian shallow water hydrocarbon seeps from snow hill and seymour islands james ross basin antarctica fossil hydrocarbon seeps are present in latest cretaceous maastrichtian volcaniclastic shallow shelf sediments exposed on snow hill and seymour islands james ross basin antarctica the seeps occur in the snow hill island formation on snow hill island and are manifest as large sized cement rich carbonate bodies containing abundant thyasirid bivalves and rarer ammonites and solemyid bivalves these bodies have typical seep cement phases with 13c values between 20 4 and 10 7 and contain molecular fossils indicative of terrigenous organic material and the micro organisms involved in the anaerobic oxidation of methane including methanotrophic archaea and sulphate reducing bacteria on seymour island the seeps occur as micrite cemented burrow systems in the lopez de bertodano formation and are associated with thyasirid solemyid and lucinid bivalves and background molluscan taxa the cemented burrows also have typical seep cement phases with 13c values between 58 0 and 24 6 there is evidence from other data that hydrocarbon seepage was a common feature in the james ross basin throughout the maastrichtian and into the eocene the snow hill and seymour island examples comprise the third known area of maastrichtian hydrocarbon seepage but compared to most other ancient and modern seep communities the james ross basin seep fauna is of very low diversity being dominated by infaunal bivalves all of which probably had thiotrophic chemosymbionts but which were unlikely to have been seep obligates absent from the james ross basin seep fauna are typical obligate seep taxa from the cretaceous and the cenozoic reasons for this may have been temporal palaeolatitudinal palaeobathymetric or palaeoecological

tectonic isolation of the levant basin offshore galilee lebanon effects of the dead sea fault plate boundary on the levant continental margin eastern mediterranean abstract the continental margin of the central levant offshore northern israel and southern lebanon is characterized by a sharp continental oceanic crustal transition exhibited on the bathymetry as a steep continental slope at the base of the slope a narrow zone of faulting deforms the upper messinian recent sedimentary sequence further into the basin no major deformations are observed however onland a restraining bend along the dead sea fault plate boundary results in the formation of the lebanon and anti lebanon mountain ranges which exhibit a large positive isostatic anomaly not compensated at depth all these geologic features follow a nne ssw trend a dense network of multi channel and single channel seismic profiles covering 5000 km of ship track offshore northern israel and southern lebanon was analyzed for the purpose of characterizing the continental margin additional seismic surveys covering the area between the levant margin and the cyprean arc were examined data were then incorporated with magnetic gravity and earthquake measurements to reveal the deep crustal structure of the area and integrated with bathymetry data to describe the behavior of the young sedimentary basin fill results indicate that the levant basin offshore northern israel and southern lebanon up to beirut is more or less unaffected by the intense tectonic deformation occurring onland the transition between the deformed area onland and the undeformed levant basin occurs along the base of the continental slope along the base the upper messinian recent sedimentary sequence is cut by two sets of faults shallow growth faults resulting from salt tectonics and high angle faults marking the surface expression of a deeper crustal discontinuity the marine extension of the carmel fault zone the central levant continental margin is being reactivated by transpressional faulting of the marine continuation of the carmel fault at the base of the continental slope this fault system coincides with the sharp continental oceanic crustal transition and acts as an isolator between the levant basin and its land counterpart to the north this feature may initiate the formation of a new triple junction with the latakia ridge part of the eastern cyprean arc and the east anatolian fault

nd isotope composition of seep carbonates towards a new approach for constraining subseafloor fluid circulation at hydrocarbon seeps abstract the carbonates forming at deep sea hydrocarbon seeps provide an archive for the source and migration pathways of the seeping fluids interpretation of the archived isotopic and elemental signatures is however not straightforward because of mixing between the signals of fluids and ambient seawater limited understanding of subseafloor fluid circulation and effects of diagenetic alteration the nd isotope system is among the most widely used tracers of circulation patterns in modern and past oceans but to date nd isotopes have been rarely used in investigations of fluid migration pathways at hydrocarbon seeps to test the sensitivity of nd isotope signals of seep carbonates to record past interactions between the seeping fluids and 143nd enriched volcanic derived mineral components we performed nd sr and stable isotope analyses of the lower cretaceous barremian seep carbonates found in baska czech carpathians these seep deposits are directly underlain by a complex of mafic igneous rocks which the methane charged fluids must have passed through on their way to the seafloor the end t values measured in the seep carbonates are significantly more radiogenic than the inferred signal of contemporaneous local seawater and shifted towards the composition typical of the underlying basaltoids this is in agreement with the 87sr 86sr ratios which are markedly lower that the coeval seawater signature consistent co variance trends are observed among the measured end t 87sr 86sr and 13c values attesting increasing role of the volcanic derived fluid component with increasing contribution of methane derived carbon the results of the present approach reveal the potential of nd isotopes to fingerprint exotic fluid end members present in plumbing systems of both fossil and modern methane discharges the method can be of particular use in studies of seeps associated with plate margins where 143nd enriched igneous materials are commonly encountered in the basement or in the sediment column

3d seismic study of complex intra salt deformation an example from the upper permian zechstein 3 stringer western dutch offshore mostoftheinformationonsubsurfaceevaporiticstructurescomesfrom3dseismicdata however this data only provide limited information about the internal structure of the evaporites which is known from salt mines and salt diapir outcrops brittle intra salt layers carbonate anhy drite clay ofatleast 10 m thicknessform goodreflectors inevaporites but the structure and dynam ics of such stringers in the salt movement are poorly understood in this study we investigate the intra salt zechstein 3 z3 stringer from 3d seismic data in an area offshore the netherlands observations show complex deformation including boudinage folding and stacking reflections from thin and steep stringer parts are strongly reduced and we present different structural models andtestsofthese wecompareourobservationstostructuralmodelsfromsaltminesandanalogue numerical models of intra salt deformation a smoothed representation of the upper surface of the stringer fragments follows the shape of top salt but smaller scale stringer geometries strongly differ from this and imply boudinage the imaged disharmonic patterns of constrictional folds pro vide evidence for the complexity of the intra salt in agreement with observations in salt mines this may be explained by interaction of the layered salt rheology complex three dimensional salt flow different phases and styles of basement tectonics and movement of the overburden

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

late tertiary seismic facies and structures of the levant passive margin off central israel eastern mediterranean abstract the late tertiary seismic facies and structures of the levant passive margin off central israel in the eastern mediterranean sea were studied by the interpretation of more than 3000 km of seismic reflection profiles most of them previously unpublished single channel profiles the neogene growth and evolution of this margin was influenced by the interaction of three main processes 1 the outbuilding and loading of the margin by the nile sediments since the pliocene 2 uplift and tectonic subsidence related to the tectonic activity along the dead sea transform and 3 the effect of the above processes on the thick messinian evaporites which caused many salt tectonic features including flowage piercement diapirs slumps and en echelon listric normal faults in the supra salt sediments we suggest that the study area may be divided into two segments north and south of caesarea these segments vary in their depositional environment the amount of sediment supply and load salt related features and tectonic activity we propose that the northern segment is affected by low sediment supply and by the continued uplift of the carmel structure and that this segment may even be a part of this structure the southern segment has been affected by the deposition and loading in the nile derived sediments since the pliocene three main depositional sequences were observed in the southern segment 1 sequence i early pliocene onlaps the top of the messinian evaporites representing a rise of sea level and renewed subsidence 2 sequence ii early pleistocene is lens shaped thinning to the north west and east and was derived during a relatively short time interval from the pre nile and 3 sequence iii since the pleistocene represents a major episode of continental shelf construction

crustal structure of the levant basin eastern mediterranean abstract a seismic refraction wide angle reflection experiment was undertaken in the levant basin eastern mediterranean two roughly east west profiles extend from the continental shelf of israel toward the levant basin the northern profile crosses the eratosthenes seamount and the southern profile crosses several distinct magnetic anomalies the marine operation used 16 ocean bottom seismometers deployed along the profiles with an air gun array and explosive charges as energy sources the results of this study strongly suggest the existence of oceanic crust under portions of the levant basin and continental crust under the eratosthenes seamount the seismic refraction data also indicate a large sedimentary sequence 10 14 km thick in the levant basin and below the levant continental margin assuming the crust is of cretaceous age this gives a fairly high sedimentation rate the sequence can be divided into several units a prominent unit is the 4 2 km s layer which is probably composed of the messinian evaporites overlying the evaporitic layer are layers composed of plio pleistocene sediments whose velocity is 2 0 km s the refraction profiles and gravity and magnetic models indicate that a transition from a two layer continental to a single layer oceanic crust takes place along the levant margin the transition in the structure along the southern profile is located beyond the continental margin and it is quite gradual the northern profile north of the carmel structure presents a different structure the continental crust is much thinner there and the transition in the crustal structure is more rapid the crustal thinning begins under western galilee and terminates at the continental slope the results of the present study indicate that the levant basin is composed of distinct crustal units and that the levant continental margin is divided into at least two provinces of different crustal structure

large scale submarine rotational slumps and growth faults in the eastern mediterranean submarine slumps with areas of 1000 km2 and more disturb the continental margin of israel and nearby areas in them the plio quaternary silty clayey sediments up to 1 5 2 km thick are broken by shore parallel growth faults into 5 10 blocks which are generally rotated and tilted landward the faults flatten downward and become rooted in ridges formed by deformation of the underlying mobile messinian evaporite bearing series deformation is thin skinned and does not visibly extend to deeper levels slumping occurred only where a sufficiently thick overburden accumulated over a sufficiently well developed mobile substrate then gravitational instability developed and led to basinward sliding of the continental margin sediments over the messinian series which acted as a lubricant and a level of decollement the mobility of this series is probably caused by overpressured shale beds that are confined between the impervious evaporites this mechanism explains all the features of the slumps hitherto faults directly related to the slumps of the eastern mediterranean were not identified but since the region is tectonically active it is not possible to exclude the possibility that basinward sliding was triggered either by motion of minor underlying faults or by seismic shaking however it seems that even if this were the case slumping could be triggered only because the continental margin was anyhow gravitationally unstable or close to such a state therefore the gravitational instability was the main factor that controlled the deformation of the pliocene quaternary sediments the slumps of the eastern mediterranean resemble large scale slumps that are known from other passive continental margins in the world

origin and nature of the rapid late tertiary filling of the levant basin the recent huge gas discovery in early miocene siliciclastics offshore israel highlighted a new world class gas province and has subsequently sparked great interest in the oligocene miocene deep water sediments of the levant basin based on a dense network of seismic data we present two fundamental observations first more than half of its sedimentary column accumulated within a mere 15 of the basin9s life span i e an 6 km thick section accumulated within 37 m y post middle eocene second this young section first accumulated in the deep basin and only then did large amounts of sediments amass along the eastern levant continental margin these fundamental observations allude to two feasible source to sink scenarios 1 the thick late tertiary section is composed of large amounts of terrigenous material that originated in arabia and was transported via the israeli margin and 2 the terrigenous material originated in africa and was transported northward via the region that eventually evolved into the nile river cone our data emphasize the difficulties of the first scenario and suggest that africa was the dominant sediment source this suggestion requires the submarine transport of sediments from offshore north africa to have been northeastward and thus raises new questions regarding ocean circulation at a time in which the neo tethys was closing and the marine connection to the mesopotamian basin gradually ceased

diagenetic alteration affecting δ18o δ13c and 87sr 86sr signatures of carbonates a case study on cretaceous seep deposits from yarlung zangbo suture zone tibet china abstract seep carbonates provide excellent records of past seepage activities and have been commonly considered to preserve primary unaltered stable carbon isotope signatures however late diagenetic reactions may overprint original isotopic compositions but the mode and effect of such alterations are poorly understood in particular there are significant uncertainties regarding how carbon and strontium isotopic compositions of seep carbonates respond to diagenesis this study reports recently discovered cretaceous hydrocarbon seep deposits from the yarlung zangbo suture zone tibet china that have experienced substantial diagenetic alteration that is shown by recrystallization and secondary veins unitary linear recursive analysis was applied to 13 c values and 87 sr 86 sr ratios of the seep carbonates to evaluate the degree of secondary modification and to quantitatively constrain the compositions of primary carbonates and late diagenetic fluids the 18 o values range from 11 8 to 2 2 13 c values from 34 1 to 12 9 and 87 sr 86 sr ratios from 0 706221 to 0 706808 the heterogeneity in isotopic compositions and the observation that the most negative 18 o values occur in samples with the most extensive recrystallization indicate significant and spatially heterogeneous modification of isotope compositions during late diagenesis the linear correlations between 13 c values and 18 o values for matrix micrites r 2 0 54 and between bulk carbonate 87 sr 86 sr ratios and 18 o values r 2 0 85 are best explained by burial diagenetic overprinting of oxygen strontium and even carbon isotopic compositions rather than by meteoric water hypergenesis extrapolated values of 13 c and ratios of 87 sr 86 sr against a 18 o value of 2 average value of calcite precipitated in isotopic equilibrium with coeval cretaceous seawater that would characterize the primary carbonate give an end member 13 c value of 34 and an end member 87 sr 86 sr ratio of 0 7072 the end member isotopic values obtained by this extrapolation suggest that the primary seep carbonates with low 13 c values and high 87 sr 86 sr ratios were formed by anaerobic oxidation of methane near the seafloor in contrast the measured 18 o values and 87 sr 86 sr ratios reflect late diagenetic fluids represented by burial pore water characterized by a low 87 sr 86 sr ratio and high temperature our findings reveal that 13 c values can only be moderately and 87 sr 86 sr ratios can be significantly altered during late diagenesis and show that it is possible to quantitatively assess the primary composition of diagenetically altered seep carbonates

a prominent isotopic fingerprint of nitrogen uptake by anaerobic methanotrophic archaea abstract marine sediments represent the largest reservoir of methane on earth anaerobic oxidation of methane aom mediated by anaerobic methanotrophic archaea anme and associated sulfate reducing bacteria is the main process controlling methane emission from marine sediments recent laboratory studies have revealed that anme or aom consortia can mediate nitrogen n fixation and ammonium assimilation these processes are known to preferentially utilize 14n rather than the 15n isotope however geochemical fingerprints of microbial nitrogen uptake in marine sediments are lacking limiting our understanding of its role in modern and ancient sedimentary environments here we report prominent negative excursions of bulk sediment 15n values up to 5 at sulfate methane transitions smts where anme show peak abundances in sediments at four sites of the haima seeps of the south china sea such 15n excursions are restricted to smts suggesting that 15n depletion results from anme mediated nitrogen uptake we posit that this process is ubiquitous at the smt a reaction front in coastal and continental margin sediments worldwide resulting in similar isotope patterns negative 15n excursions are consequently a promising proxy to track aom in the geological record and to better constrain carbon and nitrogen cycling in ancient sedimentary environments

miocene to recent tectonic evolution of the eastern mediterranean new pieces of the old mediterranean puzzle the mediterranean sea and its surrounding land mass fig 1 have long been recognized as an excellent bnatural laboratoryq for the study of fundamental plate tectonic processes including rifting passive margin development contraction and associated subduction ophiolite emplacement and orogenesis and as such it is one of the most extensively studied regions of the world e g hsu et al 1975 dixon and robertson 1984 kastens et al 1990 emeis et al 1996 comas et al 1996 robertson 1998 mcclusky et al 2000 the late cretaceous to holocene tectonic evolution of the eastern mediterranean region is extremely complex and controversial and several commonly conflicting hypotheses have been proposed the scope of this special issue does not permit a full discussion of these hypotheses we refer the reader to robertson 1998 for a review however there is general agreement that the eastern mediterranean evolved as a small ocean basin during the late triassic robertson and dixon 1984 robertson et al 1991 this embryonic ocean achieved its maximum

internal configuration of the levantine basin from seismic reflection data eastern mediterranean abstract in the easternmost mediterranean the levantine basin is filled by up to 10 km of mesozoic to recent sediments next to the alpine deformation front of the cyprean arc near the junction between africa and arabia away from the deformation front the basin has undergone little deformation for the past 100 ma as evidenced by deep seismic reflection profiles mostly subhorizontal reflections image the undisturbed sedimentation above a possibly paleozoic basement two marked reflections are identified within the sedimentary fill m and k they correspond to unconformities near the deformation front and their laterally equivalent concordant surfaces basinward in the deepest part of the basin there are more than 4 km of tertiary to recent sediments within which the m reflection is well defined above the 1 5 km thick messinian evaporites and beneath the 500 m thick plio quaternary sedimentary sequence pre tertiary sediments reach up to 6 km thick beneath the k reflection and above the top basement reflection they are little deformed and possibly correspond to late jurassic cretaceous age the limit with the cyprean arc deformation front is a sharp tectonic boundary south of the hecateaus rise where the whole sedimentary fill terminates against a subvertical fault zone that can be followed down to more than 14 km depth to the east this limit changes into a 30 km wide zone of strike slip deformation that includes flower structures progressively buried basinward by tertiary to recent syntectonic sediments possibly since paleocene times the basin corresponds to the almost undisturbed part of a larger basin whose northern side has been incorporated within the alpine deformation of the cyprean arc and limited to the east by the dead sea transform system

early stage orogenesis in the timor sea region nw australia neogene collision between the australian eurasia and pacific plates was coeval with the growth of major depocentres in the timor sea seismic cross sections across these troughs identify a characteristic architecture all three lie inboard of diffuse horst like structural highs and all mimic older depressions in the top permian and upper jurassic surfaces distortion of pre tectonic aptian oligo miocene sequences indicates apparent trough subsidence was coupled to uplift of outboard highs rudimentary cross section restoration identifies negligible strike normal length change we interpret apparent neogene subsidence to reflect amplification of basement topography this was not accommodated by discrete structural inversion rather landward propagation of contractional strain caused continuous vertical amplification of basement topography at shallow levels normal faulting accommodated flexure and thin skinned collapse of detached sedimentary cover permitting it to shed away from structural highs and pond in adjacent troughs we infer that shortening of the north west shelf accommodated oblique convergence between australia and the eurasia pacific arc and speculate that the transcurrent component of this deformation was partitioned well outboard neogene modification is interpreted to reflect the earliest stages of collisional orogenesis

cretaceous alkaline lamprophyres from northeastern czech republic geochemistry and petrogenesis the northeast part of the czech republic moravia and the adjoining part of poland host a 100 km long and 15 to 25 km wide belt containing numerous isolated bodies mainly sills of lamprophyre of lower cretaceous age the lamprophyres range from mafic melanocratic to evolved feldspar rich mesocratic variants mineralogically they are characterized by compositionally zoned kaersutite phenocrysts biotite and high al ti salitic to diopsidic clinopyroxene the lamprophyres are typically alkaline as shown by high contents of p2o5 tio2 alkalies and incompatible trace elements such as light ree zr nb y ba and sr and by high ti v 50 and chondrite normalized la yb n 8 25 ratios they resemble alkali basalts basanites and nephelinites major element composition and trace element patterns and nd sr isotopic values end ca 5 5 to 6 6 and esr ca 9 5 to 24 0 indicate that the lamprophyric magma was derived from a mantle source that was compositionally similar to the source of ocean island basalts with himu affinities and some continental extension related alkali basaltic suites the lamprophyres do not show any subduction imprint they were generated in the garnet stability field by a variable degree of melting evolved lamprophyres were formed by clinopyroxene dominated fractional crystallization of mafic lamprophyric magma the lamprophyres are interpreted to have been emplaced along conduits formed during the formation of a basin graben structure in the early cretaceous

characteristics of rainfall induced landslides in miocene formations a case study of the shenmu watershed central taiwan abstract fractured and high permeability miocene formations exhibiting shallow soil layers and dense faults and an increasing number of heavy rainfall events have caused severe and frequent landslides in the shenmu watershed of central taiwan the shenmu watershed exhibited a landslide ratio that was typically greater than 1 0 during heavy rainfall events between 1996 and 2009 and can be considered one of the most landslide prone areas in taiwan the landslide ratio in the lower hillslopes is approximately 2 8 to 43 3 times greater compared with that in the upper hillslopes analyzing based on a self organized criticality soc perspective indicated that the value of the shenmu watershed 1 24 1 26 was the lowest among landslide prone areas implying that small landslides dominated the distribution of landslides documented in available records the six large landslides that occurred include four shallow landsides and two deep seated landslides with a landslide depth greater than 10 m approximately 82 3 of the small landslides constituted bank erosion landslides in the downstream watershed whereas 96 2 of the large landslides occurred in upstream areas with dense faults large landslides occurred during only heavy rainfall events in which the accumulated rainfall was greater than 1000 mm in fractured and high permeability strata with dense faults the large landslides deposited considerable amounts of sediment into streams inducing significant bank erosion landslides in the downstream watershed bank erosion in the downstream watershed caused additional small landslides along the river large landslides were typically caused by a fault density of 693 6 m km2 fractured strata with a permeability of 10 3 to 10 4 m s and high levels of accumulated rainfall exceeding 1000 mm the apparent increase in bank erosion which increased from 103 to 136 between 1996 and 2009 resulted from an increasing number of heavy rainfall events and the amount of sediment deposition caused by major landslides frequent landslides result from the increasing number of heavy rainfall events fractured rock exhibiting dense faults and steep and shallow soil morphology in the shenmu watershed

experimental models of extensional forced folds we have used single layer and multilayer clay models to study the development of forced folds above normal faults our modeling results show that the deformation patterns associated with extensional forced folding depend on the dip of the underlying normal fault and the presence of layer parallel detachments in single layer clay models extensional forced folds are upward widening monoclines anticlinal axial surfaces dip in the same direction as underlying master normal faults and synclinal axial surfaces dip in the opposite direction of master normal faults most secondary faults are upward steepening normal faults if master normal faults are steeply dipping however many secondary normal faults become high angle reverse faults at shallow depths the propagation and linkage of secondary faults into through going normal faults terminates the development of extensional forced folds more folding occurs prior to fault linkage if the master normal fault is steeply dipping rather than gently dipping most dipping beds and secondary faults are preserved in the hanging walls of the through oing normal faults in multilayer clay models with layer parallel detachments extensional forced folds are also upward widening monoclines slip on the lowest detachment laterally transfers extension induced by normal faulting and forced folding from the master normal fault to the detachment edge slip on overlying detachments accommodates minor thickness changes associated with upward widening of the fold secondary faults include low angle normal faults near the anticlinal axial surface minor thrust faults near the synclinal axial surface and high angle normal faults above the detachment edge the model predicted deformation patterns are similar to those of extensional forced folds from the gulf of suez and offshore norway this similarity suggests that our modeling results apply to extensional forced folds and can provide guidelines for interpreting field well and seismic data

the nile deep sea fan preliminary results from a swath bathymetry survey we present and discuss a set of data mainly swath bathymetry backscatter images and a few seismic data that have been recently recorded over large areas of the nile deep sea fan between water depths of 1200 and 3000 m these data demonstrate the presence of at least three distinct morphostructural provinces where interacting sedimentary tectonic and salt tectonic processes control the present day morphology and the recent evolution of the major mediterranean deep sea fan the role of the ongoing collision presently occurring between the continental eratosthenes seamount and the cyprus arc may have been and still is a determining parameter for the development of the nile deep sea fan

kinematic modelling of extensional fault propagation folding abstract many studies have shown that in extensional basins discrete faulting at depth is commonly linked to more distributed deformation in particular folding at higher levels such extensional fault propagation folds are particularly common where there is a distinct mechanical contrast between faulted basement and sedimentary cover outcrop and analogue modelling studies indicate that such folds form as upward widening zones of distributed deformation monoclines above discrete faults at depth with increasing displacement strain the folds are cut by faults as they propagate upwards into the cover to date however there has been little investigation into the kinematics of linked basement faulting and extensional fault propagation folding here we present a two dimensional kinematic model of linked basement faulting and fault propagation folding which is based upon trishear the model allows investigation of the influence of shear zone geometry and the rate of fault propagation upon the style of folds and the strains associated with them the evolution of linked basement faulting and folding predicted by the model is compared in detail to that observed in an analogue model the kinematic model reproduces well many of the features seen both in the analogue model and reported from outcrop and seismic studies

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