middle pleistocene deposits at frog hall pit stretton on dunsmore warwickshire english midlands and their implications for the age of the type wolstonian organic sediment from frog hall pit near coventry has produced pollen plant macrofossil insect ostracod and molluscan data indicative of the early part of a temperate episode in the middle pleistocene the regional stratigraphy and clast lithological characteristics of the gravels underlying the temperate deposits show that the whole sequence at the site post dates the major glaciation the wolstonian sensu mitchell et al 1973 of the midlands amino acid d l ratios from molluscan shells give mean values of 0 24 which is consistent with an age in oxygen isotope stage 9 and comparable with those from the hoxnian interglacial of east anglia this age estimate for the frog hall organic deposit places a minimum age on the wolstonian glaciation of the midlands in oxygen isotope stage 10 and therefore close in time to the anglian oxygen isotope stage 12 cold stage 1997 john wiley sons ltd

fold related faults in the syrian arc belt of northern egypt abstract late cretaceous early tertiary syrian arc folds in northern egypt include both inversion and non inversion folds these folds are well exposed in northern sinai and the northern eastern desert but exist in the subsurface in the northern western desert in northern sinai the maghara yelleg and halal inversion folds are 45 50 km long similar size inversion folds with opposite vergence exist in the subsurface in the northern western desert and include the kattaniya mubarak alamein razzak and matruh basin folds smaller non inversion compressional folds include the falig and meneidret el etheili folds in northern sinai as well as the abu gharadig anticline in the subsurface in the northern western desert among others detailed surface and subsurface structural mapping made use of the excellent exposures and good 2d and 3d seismic data and led to the identification of the fault patterns of the inversion and non inversion syrian arc folds inversion folds have fault patterns that differ from the backlimb to the forelimb the backlimbs are pervasively dissected by long nw se oriented normal faults that were formed by the regional stress field on the contrary the forelimbs of inversion folds as well as the two limbs of non inversion folds are affected by the local stress in the folded areas and are dissected by three shorter fault sets a set of hinge transverse normal faults and two conjugate sets of hinge oblique faults that have oblique slip the hinge oblique faults dominate the steeper limbs of asymmetric non inversion folds

significance of the record provided by pleistocene fluvial deposits and their included molluscan faunas for palaeoenvironmental reconstruction and stratigraphy case studies from the english midlands abstract the vast majority of pleistocene fluvial deposits in northwest europe are of cold climate origin with the most important sediment type being coarse sands and gravels formed under nival regimes less commonly sands and silts of interglacial deposition are preserved in the lower levels of major aggradations or in channels preserved beneath them molluscan faunas are common in both types of deposit although the fine grained temperate sediments show the best preservation and the most diverse assemblages this paper will discuss the types of molluscan faunas found in fluvial deposits and assess their suitability for both climatic reconstruction and stratigraphic studies while it has been clear for many years that reliable local environmental reconstructions can be made using mollusca they have been less used for regional climatic assessment work in england over the past thirty years shows that faunas obtained from fluvial sediments particularly if they contain both freshwater and terrestrial species can provide a basis for regional climatic reconstruction mollusca may also allow the separation from each other of interglacials and interstadials and permit these episodes to be more precisely defined than is allowed by other means such as palynology molluscan faunas may offer potential for the identification of temperature episodes which may have the same climatic status as interglacials but which are not recognised as such by other palaeontological evidence such as pollen the use of molluscan faunas for biostratigraphy has been firmly rejected by previous authors however recent work concentrating on sites of similar facies within single catchments has shown that both presence and absence of individual species particularly those now exotic to the british isles e g belgrandia marginata michaud and corbicula fluminalis muller can be a useful guide to relative age examples illustrating the significance of these faunas in the stratigraphic record are largely taken from the fluvial deposits of the major rivers of the english midlands warwickshire avon great ouse nene but reference is also made to other studies on the deposits of the thames the ages of the faunas described range from the cromerian interglacial to the devensian glacial stage and includes data from sites in integlacials identified in the stratigraphic record but so far not formally named

late middle pleistocene interglacial deposits at upper strensham worcestershire england pleistocene deposits containing the disarticulated skeleton of a mammoth and associated faunal and floral remains were discovered in july 1990 at upper strensham worcestershire the environmental evidence from the fauna and flora together with limited geological evidence indicates that the deposits accumulated within a low energy fluvial environment with a surrounding marsh and restricted tree cover on or close to the floodplain the patchy occurrence of trees in a species rich grassland is discussed and the climatic significance of the fauna and flora is considered the strensham site lies within the valley of the river avon which is known to contain at least five altitudinally distinct river terraces the deposits at strensham lie beneath a terraced surface that cannot be accommodated within the existing framework of terrace development in the valley and evidence is presented which may suggest that these deposits form a previously unrecognised fluvial unit the strensham member of the avon valley formation amino acid age estimates from shells taken from the fossiliferous sediments of the strensham member suggest a correlation with oxygen isotope stage 7 this correlation suggests that the temperate deposits at this site should be correlated with the temperate phase recorded at marsworth buckinghamshire and stoke goldington in the vafley of the great ouse journal of quaternary science

north sea rift system abstract the mesozoic north sea rift forms an integral part of the arctic north atlantic rift system rifting activity in the north sea commenced during the earliest triassic during the mid jurassic the central north sea underwent a temporary doming stage crustal extension peaked during the late jurassic earliest cretaceous abated subsequently and terminated altogether during the paleocene the saucer shaped cenozoic post rift basin straddles the axis of the viking and central grabens this speaks for the applicability of a depth dependent pure shear model rather than a simple shear model geophysical data indicate an important discrepancy between upper and lower crustal attenuation across the north sea rift suggesting that during rifting processes the mono discontinuity was seriously destabilized this requires a basic modification of currently favoured crustal stretching models

sedimentology palaeoecology and geochronology of last interglacial deposits from deeping st james lincolnshire england pollen plant macrofossil molluscan and coleopteran data from organic muds below the low terrace of the river welland at deeping st james lincolnshire indicate deposition in the mixed oak forest phase of a late pleistocene interglacial coleopteran and molluscan data suggest summer temperatures up to 4 c warmer than at present in eastern england and plant macrofossil material suggests a climate more continental than that of britain in the holocene no direct analogue of this biota however exists currently in europe biostratigraphical indications from the pollen coleoptera and mollusca suggest an age in the ipswichian interglacial thermoluminescence dates between 120 ka and 75 ka and amino acid ratios with a mean of 0 11 show that deposition of the sediments took place during oxygen isotope stage 5 this accurate dating of a partial ipswichian succession allows discussion of the ages of a number of other interglacial sites in eastern england of assumed ipswichian age copyright 1999 john wiley sons ltd

surface expression of the syrian arc kattaniya inverted basin in the abu roash area northeast western desert egypt structural style and tectonic history abstract the present study concerns the structural interpretation and tectonic evolution of the syrian arc structures of the kattaniya basin northeast western desert egypt published subsurface data on this basin indicates a positive inversion of jurassic early cretaceous extensional structures during the late cretaceous time in the northeastern part of the kataniya basin the abu roash area offers unique and excellent exposures to examine the structural style and constrain any deformational events upper cretaceous strata of the abu roash area are deformed by a series of ne trending left stepped en echelon oblique folds which are sequentially dissected by faults of the following development order ene and wnw trending right lateral wrenches ne trending reverse faults n s to nnw trending left lateral faults and nw tending normal faults the abu roash area is subdivided into nine structural assemblages locating on both sides of the cairo alex road detailed surface mapping and structural analysis indicate that these structural assemblages were developed throughout a transpressional wrenching mechanism oblique inversion with different convergence angles 45 at the northern margin and 30 at the southern margin in summary the tectonic history of the northeastern segment of the kattaniya inverted basin is dominated by an extension during the jurassic early cretaceous times such an extension was rejuvenated during the late cretaceous as manifested by the angular relationships within turonian strata of the abu roash formation this extensional phase was followed by a compressional phase tectonic inversion started during the santonian time reaching its paroxysm by the late senonian inversion gradually abated and there is evidence for complete cessation at the latest senonian and non deposition of the lower eocene sediments during the middle late eocene this compressional regime had completely ceased later during oligo miocene times the study area recorded a ne extension and was crossed by nw trending normal faults

the enigma of the jonah high in the middle of the levant basin and its significance to the history of rifting abstract recent giant gas discoveries within deeply buried structural highs in the middle of the levant basin have attracted the attention of the industrial and academic communities striving to understand the origin of such structures their relations to the tectonic history of the basin and their evolution through time here we focus on the jonah high which is one of the largest structures in the basin and is particularly enigmatic in its geometry dimensions and location compared to nearby structures it is buried under more than 3 km of late tertiary sediments and is associated with one of the largest magnetic anomalies in the basin though no significant gravity anomaly is observed previous studies raised several possibilities explaining its origin an ancient horst related to the early stage of basin formation late paleozoic or early mesozoic a syrian arc fold late cretaceous to neogene a giant volcanic seamount and an intrusive magmatic body a reconstruction of the evolution of this structure is proposed here based on newly produced pre stack depth migration of five selected seismic reflection lines crossing the jonah high combined with a basin wide interpretation of more than 500 2 d time migrated lines we suggest that the jonah high is a horst bounded by grabens most probably formed during continental breakup related to the neo tethys formation however unlike other extensional structures that were reactivated and inverted during the syrian arc deformation the jonah high was never reactivated rather it formed a prominent seamount that persisted for 120 140 ma until the early miocene when it was finally buried in a wider perspective the jonah horst is similar to the eratosthenes seamount a fragment of continental crust between the levant and herodotus basins

sinai hinge belt a major crustal boundary in ne africa the sinai hinge belt is a major crustal boundary in northern sinai separating different tectonic terranes this boundary started as a number of ene wsw oriented faults of precambrian or palaeozoic age and played a major role in the mesozoic and cenozoic tectonic evolution of ne africa the sinai hinge belt was reactivated by normal faulting during early mesozoic opening of neotethys and was later reactivated by dextral transpression during late cretaceous early tertiary closure of neotethys and dextral transtension in the miocene this study highlights the structural characteristics of the hinge belt and the nature of deformation of its fault segments it also highlights the role of this basement structure as a crustal boundary between terranes of different tectonic settings as well as its relationship to the structural development of the nearby areas in ne africa supplementary material a google earth image and structural form line map of rishat saada fault google earth image and landsat tm image of rishat lehman fault and g ras ebeid geological map of el risha el hamra fault landsat tm image and structural form line map of the burqa riash fault and google earth image and geological map of el bruk fault are available at www geolsoc org uk sup18697

geology and geochemistry of the huilvshan gold deposit xinjiang china implications for mechanism of gold precipitation the huilvshan gold deposit in the west junggar xinjiang china is hosted in chloritized basalts chlorite siderite altered basalts and quartz siderite rocks our study demonstrated that all these rocks were derived by alteration of basalts in a shear zone the orebodies consisting of quartz sulfide veins and disseminated sulfides formed in five stages quartz muscovite i disseminated sulfides ii quartz ankerite sulfide iii quartz calcite sulfide iv and quartz calcite v auriferous minerals are native gold in stage iii and electrum in stage iv during alteration of basalts in the shear zone ore forming elements were released from basalts to ore forming fluid compared with fresh basalts sulfide bearing chloritized basalts contain much higher sr ba p la ce u mn ni zn as ag and au contents phase analysis of the as cu fe s o system with the supcrt92 software package indicates that a decrease of the ah2s value caused by the fluid rock reactions and crystallization of sulfides induced gold precipitation

late pleistocene deposits at block fen cambridgeshire england organic sediments in a gravel quarry at block fen cambridgeshire form a sheet dividing lower from upper gravels analyses of pollen macroscopic plant remains and molluscs from these organic sediments are presented they indicate the presence of temperate freshwater and slightly brackish fine floodplain sediments which on the basis of the palaeobotany are correlated with the temperate ipswichian stage the freshwater sediments ascribed to ipswichian substage iib occur at ca 3 m od marine influenced tidal sediments ascribed to ipswichian substage iii occur at ca 6 m od no evidence was found for the presence of more than one temperate stage in the sequence the lower gravels are then correlated with the cold wolstonian stage and the upper gravels with the cold devensian stage in contrast to the woodland environments indicated by the palaeobotany of the ipswichian organic sediments post ipswichian pollen diagrams and macroscopic plant remains in the upper suite of sands and gravels indicate open tree less vegetation typical of the cold devensian stage they also contain a typical cold stage mollusc fauna the sediments containing these floras and faunas are associated with thermal contraction cracks indicating the presence of permafrost the final sand and gravel aggradation in the devensian forms the block fen terrace near 0 m od the evidence indicates that it is younger than the lacustrine sediments resulting from the blocking of the fenland at the wash by late devensian ice at ca 18 5 ka bp the sequence at block fen is related to nearby ipswichian and devensian sediments at chatteris march wimblington and mepal and to deposits at wretton on the east margin of fenland the correlation permits an outline reconstruction of the history of the valley carrying the river great ouse between the isle of ely and the chatteris and march islands from the time of a gravel aggradation before the ipswichian to the flandrian the reconstruction shows the time and level of the ipswichian marine incursion into the middle level of fenland and the extent of aggradation and erosion in the devensian

structural architecture and tectonic evolution of the yelleg inverted half graben northern sinai egypt abstract the gebel yelleg area includes a number of folds belonging to the northern sinai syrian arc structures detailed surface structural mapping and subsurface seismic and borehole data show that the gebel yelleg structures are related to late cretaceous early tertiary inversion of a jurassic asymmetric or half graben formed during the opening of neotethys the inversion structures include a large 45 km long asymmetric fold yelleg anticline with a steep flank overlying the southeastern main bounding fault of the inverted half graben as well as some right stepped en echelon folds overlying the northwestern bounding fault of the half graben the large inversion anticline is dissected by a large number of long nearly orthogonal normal faults whereas the en echelon folds are dissected by transverse normal faults and two sets of oblique slip faults inversion of the northern sinai extensional basins is related to africa eurasia convergence and was probably transpressional with a small component of dextral slip this study shows that the magnitude of inversion in the northern sinai fold belt decreases toward the southern boundary of the jurassic extensional province

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

luminescence dating of sediments using single aliquots new procedures abstract the application of luminescence dating to quaternary sediments has been hampered by the labour intensive procedures involved determination of equivalent doses using single aliquots measured using an automated luminescence reader offers a significant reduction in labour equivalent dose determinations using two single aliquot additive dose methods are compared with equivalent doses measured using standard multiple aliquot methods for a suite of 12 dune sand samples from southwest north island new zealand the single aliquot correction method based upon adjusting the magnitude of the measured luminescence signal is found to give underestimates for those samples whose equivalent dose is greater than 80 gy and whose luminescence response to dose is non linear a second correction method based upon adjusting the value of the total added dose that the sample has received is described this second method gives equivalent dose results similar to those measured using standard multiple aliquot methods over the range from 0 1 to 400 gy

a late middle pleistocene temperate periglacial temperate sequence oxygen isotope stages 7 5e near marsworth buckinghamshire uk abstract river channel and colluvial deposits near marsworth buckinghamshire record a temperate periglacial temperate sequence during the late middle pleistocene the deposits of a lower channel contain tufa clasts bearing leaf impressions that include acer sp and sorbus aucuparia and containing temperate arboreal pollen attributed to ash dominated woodland the tufa probably formed at the mouth of a limestone spring before being redeposited in a small river whose deposits contain plant remains mollusca coleoptera ostracoda and vertebrate bones of temperate affinities the sediments sedimentary structures and limited biological remains above the lower channel deposits indicate that fluvial deposition preceded climatic cooling into periglacial conditions fluvial deposition recurred during a later temperate episode as shown by the mammalian bone assemblage in stratigraphically higher channel deposits the upper channel deposits are confidently attributed to oxygen isotope sub stage 5e ipswichian on the basis of their vertebrate remains however the age of the lower channel deposits is less clear the mammalian and coleopteran remains in the lower channel strongly suggest correlation with oxygen isotope stage 7 on the basis of their similarities to other sites whose stratigraphy is better known and the clear difference of the lower channel assemblage from well established faunas of ipswichian or any other age by contrast u th dating of the tufa clasts suggests an age post 160 ka bp while aile ile ratios on mollusca point to an ipswichian age and younger four ways of interpreting this age discrepancy are considered the preferred one correlating the lower channel deposits with oxygen isotope stage 7

optical dating studies of quartz and feldspar sediment extracts abstract continuing developmental work into optical dating has led to some clarification of the optical behaviour of quartz and feldspar sediment extracts we have verified the key assumption intrinsic to the method that the optical signal is zeroed completely upon exposure to daylight we also show that the rate of zeroing in optical dating is much more rapid than it is in tl dating studies concerned with the extraction of the thermally stable signal from laboratory irradiated samples showed that problems may arise from medium to high temperature preheating of young samples optical alternatives to thermal stabilization were tested using dye and krypton lasers using a krypton laser we have succeeded in obtaining an equivalent dose of 0 0 0 7 gy for the quartz from a modern intertidal sand and an average dose of 120 22 gy for the feldspar extract of a 70 ka sand unit both were obtained using six wavelengths from the infrared to the violet and no dependence on wavelength was found we found that the photon energies of infrared and deep red light can stimulate luminescence in unirradiated quartz and feldspar extracts of sediments this was not expected and suggests that the process of trap emptying is more complex than we had envisioned but implies a far greater than expected degree of technical flexibility for the optical dating method

tectonic analysis of the dead sea rift region since the late cretaceous based on mesostructures we have measured the orientations of small faults slickensides tectonic stylolites vein with secondary mineralization small folds and dikes in israel and sinai these structures are indicators of paleo stress or strain and provide the pattern of tectonic deformation data were collected at 130 stations most with tens of separate measurements most stations showed consistent deformation stations were located on exposures ranging from precambrian crystalline rocks to pleistocene sediments we have defined two tectonic stress fields each relatively uniform in both time and space one stress field with dominating maximum horizontal compression trending w to wnw in the late cretaceous to eocene rocks in the folds and plateaus west of the dead sea rift the second field with dominating horizontal extension trending e to ene in all rocks inside the rift and proximal thereto the first stress field is called the syrian arc stress and the second is called the dead sea stress a change in style of tectonic deformation which corresponds to the two stress fields is manifested also in the major structures in israel the late cretaceous to neogene deformation is characterized by long wavelength folds and monoclines whereas the neogene to recent deformation is characterized by normal and strike slip faults and volcanic activity

structural architecture and tectonic evolution of the maghara inverted basin northern sinai egypt abstract large ne sw oriented asymmetric inversion anticlines bounded on their southeastern sides by reverse faults affect the exposed mesozoic and cenozoic sedimentary rocks of the maghara area northern sinai seismic data indicate an earlier jurassic rifting phase and surface structures indicate late cretaceous early tertiary inversion phase the geometry of the early extensional fault system clearly affected the sense of slip of the inverted faults and the geometry of the inversion anticlines rift parallel fault segments were reactivated by reverse slip whereas rift oblique fault segments were reactivated as oblique slip faults or lateral oblique ramps new syn inversion faults include two short conjugate strike slip sets dissecting the forelimbs of inversion anticlines and the inverted faults as well as a set of transverse normal faults dissecting the backlimbs small anticline syncline fold pairs ornamenting the steep flanks of the inversion anticlines are located at the transfer zones between en echelon segments of the inverted faults

palaeobiogeography of the bajocian oxfordian macrofauna of gebel maghara north sinai egypt implications for eustacy and basin topography abstract based on newly collected material from the bajocian oxfordian rocks of gebel maghara north sinai egypt and available published information the palaeobiogeographic pattern and the dispersal potential of the macrofauna including bivalves ammonites corals and brachiopods are investigated both clustering methods and ordination techniques were applied and evaluated during bajocian times g maghara occupied an intracratonic setting and was isolated from the main ocean by islands and shallows these barriers may have limited the dispersal potential of the macrofauna and impeded the faunal exchange with even nearby areas although these barriers had disappeared by rejuvenation of faults during an active rift stage in bathonian times the same biogeographic patterns continued which may be related to the global sea level lowstand by callovian times a time of global sea level highstand in contrast the fauna of the study area became very similar to that of northeastern africa similarly diversity and extinction rates increased from the middle bathonian onward which may reflect intrusion of cosmopolitan taxa due to the newly established open marine setting and the global sea level highstand towards the oxfordian lowering of temperature may have limited the dispersal ranges of the macrofauna within the ethiopian province as a result a southeastern subprovince indo malagasy including tanzania madagascar and india became established although the geographic patterns of the different faunal groups exhibit some similarities resulting from abiotic factors such as sea level climate and basin topography biotic characteristics such as life habits and larval development played the dominant role in shaping the distribution pattern the dispersal potential was highest for ammonites followed by that of corals and then bivalves brachiopods had the lowest dispersal potential

an analysis of the molluscs from an ipswichian interglacial river channel deposit at maxey cambridgeshire england a freshwater and land molluscan assemblage from an ipswichian stream channel at maxey cambridgeshire is discussed the presence of belgrandia marginata and vallonia enniensis suggests that summer temperatures may have been somewhat warmer in the ipswichian period the assemblage represents the silting processes under relatively quiet water conditions possibly in a side channel or backwater of a meandering river system

towards a late middle pleistocene non marine molluscan biostratigraphy for the british isles abstract the fossils of non marine mollusca are among the most prominent in pleistocene deposits they were one of the first fossil groups to be noted in the literature as early as the beginning of the 18th century with the stabilisation of taxonomies in the 19th century numerous publications appeared with faunal lists of interglacial taxa but few attempts were made to use the data for interpretation work from 1950 onwards especially by sparks and kerney in britain puissegur in france and by lo ek in central europe used a quantitative approach to sorting counting and interpreting assemblages despite the adoption of this rigorous methodology to molluscan studies interglacial faunas were used primarily to reconstruct past environments and although faunal changes through the pleistocene were recognised it was thought that non marine mollusca were inherently badly fitted for use as tools for dating in the classic geological sense recent work coupled with the re evaluation of sites described in the literature has allowed non marine molluscan faunas to be used as biostratigraphic indicators biostratigraphic schemes evolved from this work are comparable with parallel investigations using mammalia coleoptera and lithostratigraphy calibrated by a number of geochronometric methods but may be at variance with pollen biostratigraphies

structure and deformation history of the bitlis suture near lake hazar southeastern turkey detailed mapping of the bitlis suture zone near lake hazar shows that it is composed of three tectonostratigraphic units which crop out as distinct north dipping thrust slices from south to north these are the puturge metamorphic complex the maden melange and the elazig igneous complex the puturge metamorphic complex consists of pre tertiary continental margin sediments metamorphosed to the greenschist facies during the campanian maastrichtian and deformed by four generations of structures these are in sequence 1 isoclinal folds and a transposition foliation 2 open folds crenulation cleavage and north dipping thrust faults 3 kink bands and 4 small displacement faults the maden melange represents middle eocene back arc basin sediments and volcanics metamorphosed to the greenschist facies and deformed by three generations of structures 1 a north dipping cleavage 2 kink bands and 3 small displacement faults the elazig igneous complex comprises an imbricated maastrichtian early eocene island arc and young marginal basin terrain thrust faults between units are north dipping listric and form a thin skinned system these features suggest the following deformational and tectonic history the puturge metamorphic complex was generated by isoclinal folding and metamorphism of sediments composing the arabian continental margin during campanian maastrichtian ophiolite obduction to the south the elazig arc developed on the deformed margin because of subsequent southward subduction of oceanic lithosphere the arc migrated to the north opening a back arc basin by the early eocene the back arc basin was filling with volcaniclastics of the maden melange and the elazig arc collided with a continent to the north during middle to late eocene convergence caused thrust stacking of the elazig maden and puturge complexes second generation deformation in the puturge complex and first generation deformation in the maden melange continued convergence with the arabian plate in the late miocene caused kink banding in the puturge and maden complexes since the late miocene this convergence has been accommodated by shortening and thickening along numerous internal faults

pleistocene deposits at stoke goldington in the valley of the great ouse uk at stoke goldington in the valley of the great ouse in buckinghamshire a river terrace at a height of about 7 m above the floodplain is underlain by fluvial sediments representing climatic fluctuations in the late middle pleistocene near the base of the succession at a level only 1 m above the modern floodplain a fossil assemblage including pollen plant macrofossils molluscs insects and ostracods provides evidence for the local development of herb rich grassland under temperate climatic conditions the fossil record amino acid racemisation ratios and uranium disequilibrium dating all suggest deposition of this material during oxygen isotope stage 7 the deposits containing the temperate assemblage are immediately overlain by typical cold climate gravels of the great ouse these have been subjected to a later cut and fill episode with the fill accumulating in cool climatic conditions the cut and fill episode was succeeded by aggradation forming the overlying terrace surface amino acid racemisation ratios indicate that the fill was emplaced and the terrace surface created during or after oxygen isotope stage 5 1996 john wiley sons ltd

longitudinal evolution of the suez rift structure egypt abstract a three dimensional study of the structure of the suez rift has been carried out using field and subsurface data in an attempt to determine the role of transverse faults and the longitudinal evolution of the rift as in most intracontinental rifts the structure of the gulf of suez area is governed by normal faults and tilted blocks whose crests constitute the main target of exploratory wells the fault pattern consists of two major sets of trends 1 1 longitudinal faults parallel to the rift axis and created in an extensional regime where 3 was trending ene wsw and 2 2 transverse faults with a n s to nne ssw dominant trend the transverse faults are inherited passive discontinuities while most of the longitudinal faults were created during neogene times in a purely extensional regime both sets were simultaneously active producing a zigzag pattern and rhombic shaped blocks the transverse faults can show horizontal strike slip components and act as relays between major normal faults although the suez rift appears as a simple narrow elongated trough dominated by two almost symmetrical shoulders its internal structure is asymmetrical cross profiles show that all the major blocks are tilted in the same direction however the tilt direction changes twice along the rift to the north and to the south of the rift the blocks are tilted eastward while in the central part they are tilted westward to the north the change of dip is accompan ed by a graben type twist zone without transverse faulting at least in the neogene series to the south the change of dip is accompanied by a more complex structure involving both a major transverse fault and a horst type twist zone in this latter case the transverse fault does not cut through the entire rift balanced cross sections established from subsurface data show that the tilt angle and the amount of extension increase from north to south while the width of the blocks decreases indicating a pole of opening close to the northern end of the gulf minimum values for the amount of opening range from 5 km in the north to about 20 km in the south

rejuvenation of the tethyan passive continental margin of northern sinai deformation style and age gebel yelleq area abstract detailed field mapping and structural analysis of the northeastern and southeastern parts of gebel yelleq the largest fold among the northern sinai folds indicate the presence of two ene oriented dextral wrench zones the northern meneidret el etheili wrench zone is represented by right stepped en echelon doubly plunging folds whereas throughgoing wrench faults characterize the southern minsherah wrench zone the steep southeastern flank of gebel yelleq asymmetric fold makes an acute angle with the wrench zones and is orthogonal to the nw se directed shortening direction indicated by mesostructures similar structural relations are evident in the other major folds of northern sinai gebels el maghara and halal a structural model is proposed for the deformation of northern sinai late cretaceous tertiary rejuvenation of the early mesozoic passive continental margin of the neotethys proceeded via right lateral wrenching in northern sinai and is related to the oblique convergence between africa arabia and eurasia during the closure of the neotethys as a result wrench zones developed above the early rift faults e g meneidret el etheili and minsherah wrench zones also nw se directed shortening related to and parallel to the convergence of africa arabia and eurasia deformed the blocks lying between the wrench zones through the development of ne sw oriented thrust faults at acute angles to the wrench zones these thrusts ruptured the precambrian basement and propagated upward through the overlying sedimentary cover as listric thrust faults forming large fault propagation folds in gebels yelleq el maghara and halal these thrusts underlie the steep southeastern flanks of these folds and are exposed in gebels el maghara and hamayir the depth to detachment of these thrusts progressively increases southward to a value underneath the gebel yelleq area close to the brittle ductile transition of the crust the deformation reached its zenith in the early late senonian and probably continued into the early miocene the northern sinai fold belt characterizes an unstable crustal block separated from a tectonically stable crustal block to the south in central and southern sinai by a belt of ene oriented closely spaced faults forming what is called the central sinai hinge belt

fault block rotation and footwall erosion in the southern suez rift implications for hydrocarbon exploration abstract a dataset in the southern suez rift including 400 km 2 of 3d depth migrated seismic data thirty six boreholes with geological information and outcrop data from several exposures was examined and interpreted in order to understand the controls on the erosion of the pre rift reservoirs at the updip edges of tilted fault blocks and its impact on hydrocarbon exploration surface and subsurface mapping demonstrated the existence of five regional major tilted fault blocks bounded by major down to the northeast rift parallel normal faults these blocks are characterized by steep stratal dip 30 40 and their bounding faults are dipping at 20 30 toward the ne the major faults in the area have been subdivided into three phases based on their age the first phase faults were formed at the early rift opening phase and were contemporaneous with the deposition of the lowermost syn rift unit nukhul formation the second phase faults are contemporaneous with deposition of the rudeis formation main syn rift unit while the third phase faults are the youngest detailed study indicates that the first phase faults controlled the rotation of the tilted fault blocks and played a major role in the erosion of the pre rift reservoirs and top seal units at the updip edges of these blocks the lowermost syn rift unit nukhul formation was deposited in the downdip areas of the tilted faults blocks and did not cover the updip eroded areas a proposed model to demonstrate the risk of drilling the crests of tilted fault blocks close to the main block bounding faults is described in this paper and can be applied in other highly extended rift basins

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

eemian climate fluctuations observed in a european pollen record recent ice core data from greenland1 2 suggest that the climate during the last interglacial period the eemian was more unstable than that of the holocene about 10 000 years ago to the present being characterized in particular by a series of cold episodes each lasting about 70 to 750 years subsequent analysis of a second greenland ice core3 4 however failed to corroborate the details of these eemian climate fluctuations a result that may be attributable to the effects of ice flow4 to resolve this discrepancy it is imperative to seek alternative sources of information about the eemian climate here we present climate reconstructions from pollen data from the annually laminated eemian lake sediment record at bispingen5 and from the eemian and holocene peat records at la grande pile6 the former record indicates that an initially warm period of 2 900 yr was followed by cooling and a series of colder episodes one of which had winter temperatures comparable to those at the end of the preceding cold stage the latter records show greater climate instability during the eemian than the holocene these results are in broad agreement with those from the grip ice core but contrast both with the gisp2 core3 4 and with recent high resolution marine records from the north atlantic7 8

an absolute chronology for the raised beach and associated deposits at sewerby east yorkshire england the raised beach sediments revealed in the cliffs at sewerby east yorkshire are widely regarded as ipswichian in age previously reported evidence for this dating is reviewed and new results from a range of luminescence dating techniques applied to the blown sand deposit overlying the raised beach are reported these provide the first absolute date for the sewerby site of 120 84 11 82 ka which places the blown sand at the boundary between oxygen isotope stages ois 5e and 5d as the underlying raised beach is little older than the blown sand it probably formed during ois stage 5e as suggested by the faunal evidence

evidence of two temperate episodes in late pleistocene deposits at marsworth uk in the british quaternary two post cromerian interglacials the hoxnian and the ipswichian are recognized1 evidence of additional interglacials in this interval is widely accepted in the oceanic record of quaternary events2 and the possibility that at least one additional interglacial of this age is represented in britain has been discussed3 5 however in the absence of datable interglacial deposits which are seen to overlie one another the issue has remained controversial we describe here deposits at marsworth uk fig 1 where there is evidence of two temperate episodes and of intervening periglacial conditions stratigraphical superposition is established beyond any reasonable doubt the later deposit relates to the temperate woodland stage of the ipswichian interglacial dating of the earlier temperate material by the 230th 234u disequilibrium method indicates an interglacial episode not previously established in the british quaternary

superpositional tectonic patterns along the continental margin of the southeastern mediterranean a review abstract resurgent tectonic phases superimposed their structural imprints on the continental margin of the southeastern mediterranean this margin underwent a complete cycle from a margin of a marine basin in the paleozoic to the margin of the incipient neo tethys ocean in the early jurassic through the margin of the mature ocean in the late jurassic cretaceous and paleogene it became the margin of a desiccated marine basin in the late miocene and finally became the margin of a rejuvenated marine basin after the pliocene the margin was affected by folding faulting and intermittent volcanism during the early liassic early neocomian late cretaceous oligocene and early miocene the younger tectonic phases were superimposed on the older ones reactivating them in some places and masking them in others the geological characteristics and this complex tectonic history are masked effectively by the thick messinian evaporitic sequence this smoothing effect was further enhanced by the huge pile of sediments that has been deposited by the river nile since the early pliocene

control of extensional transfer zones on syntectonic and post tectonic sedimentation implications for hydrocarbon exploration the gulf of suez red sea rift system exhibits superb outcrop examples of extensional transfer zones and displays the control of these zones on syntectonic and post tectonic sedimentation hard and soft linkage transfer zones were identified at variable scales hard linkage transfer zones form inward and outward fault kinks whereas soft linkage transfer zones form relay ramps between overlapping rift parallel faults the two types of transfer zones invariably exerted fundamental control on the deposition of syn and post tectonic sediments flow direction of drainage systems and locations of sediment entry points as well as the intensity of erosion patterns of the structurally high sediment source areas this study highlights the close relationship between the transfer zones and hydrocarbon accumulations in clastic syntectonic reservoirs in rift basins

structural style and evolution of inversion structures of horus field alamein basin northern western desert of egypt abstract high quality three dimensional 3d seismic reflection and borehole data are used to characterize in detail the structural style and evolution of inversion structures in horus oil field this field lies in the central part of alamein basin northern western desert of egypt in the hanging wall of a major jurassic early cretaceous normal fault this fault delineates the northwestern margin of the basin and extends in an ene wsw direction bounding a half graben trough in its hanging wall this trough had continued subsidence during early cretaceous time with depositional thickening of the lower cretaceous alam el bueib formation fault displacement had ceased near the top of barremian level aptian lower senonian seismically traced levels show a major ne plunging asymmetrical anticline overlying the jurassic barremian half graben this anticline is sub parallel to the inherited jurassic rifting fault at shallower cretaceous levels this fault is replaced by a set of wnw ese trending en echelon faults of considerable displacements which probably indicates a strike slip component of deformation these faults display normal separation on all displaced stratigraphic levels and tip upwards in the upper part of the upper cretaceous succession this marks a considerable change in the tectonic mode of the area nw se extensional faults were developed perpendicular to the fold axis dissecting the anticline into several blocks entrapping hydrocarbons detailed seismic structural analysis of growth strata indicates that the fold initiated in early senonian time was associated with the inversion of the earlier jurassic barremian half graben this basin inversion is attributed to the syrian arc event that dominated north africa during the late cretaceous time and continued through to the early miocene low fold amplitude coupled with normal displacements on the deep seated ene wsw trending jurassic barremian fault indicate a mild phase of positive inversion the upper senonian eocene stratigraphic sequences increased in thickness in the back troughs that were associated with basin inversion

land sea correlations in the pleistocene based on isoleucine epimerization in non marine molluscs the correlation between the oxygen isotope stratigraphy of the oceans and continental stratigraphic records is one of the main challenges for quaternary research most continental classifications however are based on techniques and hypotheses that predate recent advances nevertheless the deep sea oxygen isotope global stratigraphic framework has been extended to the continents by means of some long sequences1 but these are exceptional and regional geology is unsatisfactorily classified for correlation with the oxygen isotope signal because successive geological events produced similar evidence homotaxis geochronometric dating is essential for correlation but available methods are highly site regional or sample specific fortunately non marine molluscs are ubiquitous in time and space and here we use the time dependent epimerization of l isoleucine in these fossils to subdivide the pleistocene of the british isles and to identify more events than recognized by the existing classification2 by calibrating the relative aminostratigraphic scale with independent dating methods we have set up a geochronology which is the basis for land sea correlations back to oxygen isotope stage 15