reply to discussion on geological offsets and age constraints along the northern dead sea fault syria journal 167 1001 1008 we welcome discussion on the geology of the dead sea fault in syria but we have to disagree with westaway s 2004 and discussion mapping assumptions his estimates of timing of fault slip and his proposed offsets and slip rates as he notes our new 40ar 39ar ages on the basalts adjacent to the dead sea fault significantly clarify and refine the chronology of the lavas westaway 2004 used the old whole rock k ar ages of mouty et al 1992 in nw syria to constrain timing of fault motion and slip rates the dispute appears to relate to the interpretation of the relationship between the basalts and the strike slip fault westaway suggests that the northern dead sea fault was active before eruption of the lavas our mapping clearly shows that the fault post dates and cuts both the coastal ranges folding and the basaltic flows that unconformably overlie the folded mesozoic sedimentary rocks westaway claims that the northern dead sea fault in western syria is transpressive not transtensional this is difficult to understand when the northern dead sea fault is split along the al ghab depression a classic rhomb shaped transtensional basin where inward dipping normal faults searle et al 2010 fig 3a e

the quaternary evolution of the gulf of corinth central greece coupling between surface processes and flow in the lower continental crust abstract the gulf of corinth in central greece is an active normal fault zone with particularly clear evidence of isostatic footwall uplift constrained by quaternary marine terraces and hanging wall subsidence and sedimentation it is bounded to the south by a pliocene to early pleistocene sedimentary basin which is now eroding into the gulf previous work has suggested that the relief across this region has increased dramatically since the early pleistocene due to the isostatic response to increased rates of footwall erosion and hanging wall sedimentation it is indeed assumed here that incision accompanying the draw down of global sea level at 0 9 ma during the first major pleistocene glaciation initiated the erosion of the basin south of the gulf of corinth and so abruptly increased the sedimentation rate in the gulf the resulting transient thermal and isostatic response to these changes is modelled with the subsiding depocentre and eroding sediment source coupled by flow in the lower continental crust the subsequent enhancement of relief involving an increase in bathymetry from near zero to 900 m and 500 m of uplift of the eroding land surface in the sediment source is shown to be a direct consequence of this change the model is sensitive to the effective viscosity of the lower crust and can thus resolve this parameter by matching observations a value of 6 1019 pa s is indicated suggesting a viscosity at the moho no greater than 1018 pa s similar transient topographic effects caused by increased rates of sedimentation and erosion are likely to be widespread within the geological record suggesting that this coupling process involving flow in the weak lower crust may be of major geological and geomorphological importance

rheological differences between archaean and younger crust can determine rates of quaternary vertical motions revealed by fluvial geomorphology surface uplift is widely observed in subaerial regions of continental crust that are distant from plate boundaries often revealed by river terrace staircases with altitude ranges of several hundred metres which typically span the quaternary this characteristic geomorphology has been explained by forcing of flow in the weak lower crustal layer by surface processes non steady state erosion and cyclical loading by ice sheets and sea level fluctuations this study tests this interpretation by showing that analogous river terrace staircases are absent in archaean crust which lacks the weak lower crustal layer found elsewhere

the obliquity controlled early pleistocene terrace sequence of the gediz river western turkey a revised correlation and chronology the buried early pleistocene river terrace record of the gediz river around kula western turkey has previously been considered to span the time interval equivalent to marine isotope stages mis 58 37 c 1 6 1 2 ma with the frequency of terrace formation mirroring obliquity driven climate change whereas progressive pleistocene incision of the gediz river is seen as a response to regional uplift the timing of fluvial incision leading to terrace formation and subsequent new floodplain development is believed to be climate controlled with incision deposition cycles resulting from varying sediment discharge conditions a direct consequence of changing climate and related vegetation change new outcrop observations downstream of the original field area alongside recently published geochronological data and improved understanding of the volcanic sequence all now suggest that the previously published interpretation is incorrect here we present a revised stratigraphy based upon terrace gradients of c 0 004 0 005 previously 0 001 in which 11 terraces are identified but only terraces gt11 the oldest to gt6 pre lava incursion predate volcanism the available geochronology suggests that terraces gt6 post first lava incursion to gt1 relate to the time interval mis38 28 c 1 26 1 ma however despite penecontemporaneous volcanism terrace formation continues to reflect sediment discharge changes predominantly controlled by regional climate change

kinematics of active left lateral faulting in se turkey from offset pleistocene river gorges improved constraint on the rate and history of relative motion between the turkish and arabian plates in the arabian platform of se turkey abundant evidence exists of fluvial incision by c 110 10 m since the late early pleistocene starting in or around marine oxygen isotope stage 22 at 870 ka this incision which has accompanied regional surface uplift as the isostatic response to regional erosion has progressively locked rivers into their gorges in landscape that formerly had much lower relief we use this effect to estimate 4 44 0 06 km of left lateral slip on this time scale on the golbasi turkoglu fault a segment of the east anatolian fault zone from offset river gorges giving a slip rate of 5 10 0 07 mm a 1 piercing points indicate that this fault has slipped a total of 19 km making its age 3 73 0 05 ma a total of 33 km of relative motion between the turkish and arabian plates is documented on this time scale in the vicinity of golbasi at an overall time averaged rate of 8 85 0 12 mm a 1 the estimated euler vector for relative motion between these plates being 0 89 0 01 ma 1 about 33 4 n 42 3 e this method can be readily applied to determine slip rates time averaged since the late early pleistocene on other strike slip fault zones worldwide

the river orontes in syria and turkey downstream variation of fluvial archives in different crustal blocks the geomorphology and quaternary history of the river orontes in western syria and south central turkey have been studied using a combination of methods field survey differential gps satellite imagery analysis of sediments to determine provenance flow direction and fluvial environment incorporation of evidence from fossils for both palaeoenvironments and biostratigraphy uranium series dating of calcrete cement reconciliation of palaeolithic archaeological contents and uplift modelling based on terrace height distribution the results underline the contrasting nature of different reaches of the orontes in part reflecting different crustal blocks with different histories of landscape evolution upstream from homs the orontes has a system of calcreted terraces that form a staircase extending to 200 m above the river new u series dating provides an age constraint within the lower part of the sequence that suggests underestimation of terrace ages in previous reviews this upper valley is separated from another terraced reach in the middle orontes by a gorge cut through the late miocene early pliocene homs basalt the middle orontes terraces have long been recognized as a source of mammalian fossils and palaeolithic artefacts particularly from latamneh near the downstream end of the reach this terraced section of the valley ends at a fault scarp marking the edge of the subsiding ghab basin a segment of the dead sea fault zone which has been filled to a depth of 1 km by dominantly lacustrine sediments of pliocene quaternary age review of the fauna from latamneh suggests that its age is 1 2 0 9 ma significantly older than previously supposed and commensurate with less uplift in this reach than both the upper and lower orontes two localities near the downstream end of the ghab have provided molluscan and ostracod assemblages that record somewhat saline environments perhaps caused by desiccation within the former lacustrine basin although they include fluvial elements the ghab is separated from another subsiding and formerly lacustrine depocentre the amik basin of hatay province turkey by a second gorge implicit of uplift this time cut through palaeogene limestone the ne sw oriented lowermost reach of the orontes is again terraced with a third and most dramatic gorge through the northern edge of the ziyaret dagi mountains which are known to have experienced rapid uplift probably again enhanced by movement on an active fault indeed a conclusion of the research in which these various reaches are compared is that the crust in the hatay region is significantly more dynamic than that further upstream where uplift has been less rapid and less continuous

quantifying the slip rates spatial distribution and evolution of active normal faults from geomorphic analysis field examples from an oblique extensional graben southern turkey abstract quantifying the extent to which geomorphic features can be used to extract tectonic signals is a key challenge in the earth sciences here we analyse the drainage patterns geomorphic impact and long profiles of bedrock rivers that drain across and around normal faults in a regionally significant oblique extensional graben hatay graben in southern turkey that has been mapped geologically but for which there are poor constraints on the activity slip rates and plio pleistocene evolution of basin bounding faults we show that drainage in the hatay graben is strongly asymmetric and by mapping the distribution of wind gaps we are able to evaluate how the drainage network has evolved through time by comparing the presence size and distribution of long profile convexities we demonstrate that the northern margin of the graben is tectonically quiescent whereas the southern margin is bounded by active faults our analysis suggests that rivers crossing these latter faults are undergoing a transient response to ongoing tectonic uplift and this interpretation is supported by classic signals of transience such as gorge formation and hill slope rejuvenation within the convex reach additionally we show that the height of long profile convexities varies systematically along the strike of the southern margin faults and we argue that this effect is best explained if fault linkage has led to an increase in slip rate on the faults through time from 0 1 to 0 45 mm yr by measuring the average length of the original fault segments we estimate the slip rate enhancement along the faults and thus calculate the range of times for which fault acceleration could have occurred given geological estimates of fault throw these values are compared with the times and slip rates required to grow the documented long profile convexities enabling us to quantify both the present day slip rate on the fault 0 45 0 05 mm yr and the timing of fault acceleration 1 4 0 2 ma our results have substantial implications for predicting earthquake hazard in this densely populated area calculated potential mw 6 0 6 6 enable us to constrain the tectonic evolution of the graben through time and more widely demonstrate that geomorphic analysis can be used as an effective tool for estimating fault slip rates over time periods 106 years even in the absence of direct geodetic constraints

dating quaternary volcanism and incision by the river tigris at diyarbakir southeast turkey new high precision ar ar dating of basalt underlying the city of diyarbakir southeast turkey constrains the quaternary incision history of the river tigris strengthening the pre existing chronology based on magnetostratigraphy and k ar dates the basalt which overlies tigris terrace gravel 70 m above the river is part of the karacadag shield volcano complex centred ca 60 km to the southwest the reverse magnetised diyarbakir basalt one of relatively few flow units to reach the tigris valley axis has been dated to 1196 19 ka 2 two lower terraces have been recognised in the diyarbakir area 46 and 32 m above the present river with at least one other further downstream from this evidence the rate of middle late pleistocene incision by the tigris can be estimated it probably reached ca 0 07 mm a 1 reflecting the characteristic global increase in uplift rates observed at that time copyright 2007 john wiley sons ltd

improved modelling of the quaternary evolution of the gulf of corinth incorporating erosion and sedimentation coupled by lower crustal flow abstract numerical modelling incorporating coupling between surface processes and induced flow in the lower continental crust is used to address the quaternary evolution of the gulf of corinth region in central greece the post early pleistocene marine depocentre beneath this gulf overlies the northern margin of an older early pleistocene and earlier lacustrine basin the proto gulf of corinth basin or pgcb in the late early pleistocene relief in this region was minimal but subsequently dramatic relief has developed involving the creation of 900 m of bathymetry within the gulf and the uplift by many hundreds of metres of the part of the pgcb south of the modern gulf which forms the gulf s main sediment supply it is assumed that as a result of climate change around 0 9 ma erosion of this sediment source region and re deposition of this material within the gulf began both processes occurring at spatial average rates of 0 2 mm a 1 modelling of the resulting isostatic response indicates that the local effective viscosity of the lower crust is 4 10 19 pa s indicating a moho temperature of 560 c it predicts that the 10 mm a 1 of extension across this 70 km wide model region at an extensional strain rate of 0 15 ma 1 is partitioned with 3 mm a 1 across the sediment source 2 mm a 1 across the depocentre and 5 mm a 1 across the hinge zone in between the latter value being an estimate of the extension rate on normal faults forming the major topographic escarpment at the southern margin of the gulf this modelling confirms the view suggested previously that coupling between this depocentre and sediment source by lower crustal flow can explain the dramatic development in local relief since the late early pleistocene the effective viscosity of the lower crust in this region is not particularly low the strong coupling interpreted between the sediment source and depocentre results instead from their close proximity in detail the effective viscosity of the lower crust is expected to decrease northward across this model region due to the northward increase in exposure of the base of the continental lithosphere to the asthenosphere in the south the two are separated by the subducting hellenic slab the isostatic consequences of such a lateral variation in viscosity provide a natural explanation for why since 0 9 ma the modern gulf has developed asymmetrically over the northern part of the pgcb leaving the rest of the pgcb to act as its sediment source

active crustal shortening in ne syria revealed by deformed terraces of the river euphrates the africa arabia plate boundary comprises the red sea oceanic spreading centre and the left lateral dead sea fault zone dsfz however previous work has indicated kinematic inconsistency between its continental and oceanic parts the palmyra fold belt pfb splays ene from the dsfz in sw syria and persists for 400 km to the river euphrates but its significance within the regional pattern of active crustal deformation has hitherto been unclear we report deformation of euphrates terraces consistent with quaternary right lateral transpression within the pfb indicating anticlockwise rotation estimated as 0 3 ma 1 about 36 0 n 39 8 e of the block between the pfb and the northern dsfz relative to the arabian plate interior the northern dsfz is shown to be kinematically consistent with the combination of euler vectors for the pfb and the red sea spreading resolving the inconsistency previously evident the sw pfb causes a significant earthquake hazard previously unrecognized to the city of damascus

reconstructing the interacting effects of base level climate and tectonic uplift in the lower mino river terrace record a gradient modelling evaluation the origin of the lower mino river terraces in the nw iberian peninsula has been a topic of debate since the 1940s various hypotheses about their main controlling factors have been put forward but general consensus is still lacking field studies of terrace distribution and the weathering of quartzite pebbles in the terrace deposits demonstrated that terrace longitudinal correlation is not parallel to the current river bed in addition the longitudinal profile model fluver2 was used to simulate the profile evolution of the mino river over the past 450 ka a reconstructed longitudinal profile and an offshore climate record were used as inputs several scenarios with variable uplift rates were investigated and evaluated against properties of four selected reaches along the river for a match with the number of terraces their relative altitude timing and sediment thickness an uplift scenario with a net constant vertical uplift rate of 0 08 m ka 1 yielded the best results the best fit scenarios indicate that base level changes from glacioeustatic changes in combination with tectonic uplift are the main driving forces of the observed terrace formation and valley incision contrary to most nw european fluvial systems the timing of upstream controlled sediment supply has a less dominant effect on terrace formation this can be explained by the close proximity to the narrow passive atlantic margin

ar ar dating of late cenozoic basaltic volcanism in northern syria implications for the history of incision by the river euphrates and uplift of the northern arabian platform 1 ar ar dating of basalt flows capping terrace deposits of the river euphrates in northern syria has provided a new quantitative chronology for the late cenozoic evolution of this important river system and for the associated history of surface uplift of the northern arabian platform through which it flows a region of relatively strong crust that has experienced only slow deformation notably fluvial deposits 65 m above the euphrates are overlain by basalt dated to 2717 20 ka those 45 m above the river are overlain by basalt dated to 2116 39 ka and those 8 9 m above the river are overlain by basalt dated to 402 11 ka these new dates require the previous dating scheme based on paleolithic archaeology to be revised the euphrates terrace deposits and the associated incised valley are much older than was previously thought rates of incision by the euphrates providing a proxy for regional surface uplift that is inferred to be the isostatic response to regional erosion have varied significantly over the past 3 ma with indications that between 1 2 and 0 9 ma there was regional subsidence which gave rise to fluvial aggradation this unusual pattern involving reversals in the sense of vertical crustal motions is interpreted to be a consequence of a relatively cold and thin mobile lower crustal layer no more than 5 km thick evidently due to the presence of a much thicker underlying layer of mafic underplating at the base of the crust this study thus indicates previously unsuspected complexity in the isostatic response to regional erosion in an area of high crustal stability

late cenozoic surface uplift revealed by incision by the river euphrates at birecik southeast turkey incision by the river euphrates has created a dramatic erosional landscape in the northern arabian platform in se turkey we obtain accurate heights of its terrace deposits in the birecik area using differential gps and summarise evidence regarding heights of late miocene basalt flows and low altitude wetland sediments we thus estimate 600 m of uplift since the early late miocene 9 ma represented by 270 m of fluvial incision the difference reflecting downstream channel lengthening as the coastline has retreated to the persian gulf 1400 km away the oldest recognised sediments inset below this level form a thick aggradation between 100 and 130 m above the present level of the euphrates we estimate that this accumulated during 5 3 ma when uplift rates were low such that aggradation was necessary to maintain a downstream channel gradient in response to the coastal retreat palaeolithic artefacts have been reported locally in euphrates deposits up to 80 m above present river level which we tentatively date to 1 8 ma the euphrates subsequently incised to within 10 m of its present level before aggrading 45 m higher in the late early pleistocene the final 55 m of incision reflects the increase in uplift rates observed worldwide in the early middle pleistocene following the mid pleistocene revolution

circulation changes and nutrient concentrations in the late quaternary aegean sea a nonsteady state concept for sapropel formation sapropel forming conditions we identify the start of seasonal stratification and highlight a lag in d 18 o response of the planktonic foraminifer n pachyderma to termination t1b as identified in the d 18 o record of g ruber by use of a simple model we determine that this offset cannot be a function of bioturbation effects the lag is of the order of 1 kyr and suggests that isolation of intermediate deep water preceded the start of sapropel formation by up to 1 5 kyr using this discovery we propose an explanation for the major unresolved problem in sapropel studies namely the source of nutrient supply required for export productivity to reach levels needed for sustained sapropel deposition we suggest that nutrients had been accumulating in astagnant basin for 1 1 5 kyr and that these accumulated resources wereutilized duringthe deposition of s1 in addition we provide a first quantitative estimate of the diffusive 1 e mixing timescale for the eastern mediterranean in its stratified sapropel mode which is of the order of 450 years index terms 1050 geochemistry marine geochemistry 4835 4850 3030 marine geology and geophysics micropaleontology 3339 meteorology and atmospheric dynamics ocean atmosphere interactions 0312 4504 4267 oceanography general paleoceanography 4870 oceanography biological and chemical stable isotopes keywords sapropel mediterranean holocene foraminifera climate variability

late cenozoic uplift of the amanos mountains and incision of the middle ceyhan river gorge southern turkey ar ar dating of the duzici basalt using the ar ar technique we have obtained the first numerical dates for the pleistocene volcanism along the valley of the river ceyhan in the duzici area of southern turkey in the western foothills of the amanos mountains our six dates indicate a single abrupt episode of volcanism at 270 ka we have identified a staircase of 7 fluvial terraces at altitudes of up to 230 m above the present level of the ceyhan using the disposition of the basalt as an age constraint we assign these terraces to cold climate stages between marine oxygen isotope stages 16 and 2 indicating rates of fluvial incision equated to surface uplift that increase upstream through the western foothills of this mountain range at between 0 25 and 0 4 mm a 1 extrapolation of these uplift rates into the axis of the range suggests that the entire 2300 m of present day relief has developed since the mid pliocene a view that we confirm using numerical modelling since 3 7 ma the amanos mountains have formed a transpressive stepover along the northern part of the dead sea fault zone where crustal shortening is required by the geometry using a physics based technique we have modelled the overall isostatic response to the combination of processes occurring including crustal thickening caused by the shortening erosion caused by orographic precipitation and the resulting outward flow of mobile lower crustal material in order to predict the resulting history of surface uplift this modelling suggests that the effective viscosity of the lower crust in this region is in the range 1 2 1019 pa s consistent with a moho temperature of 590 10 c the latter value being in agreement with heat flow data this modelling shows that the nature of the active crustal deformation is now understood to first order at least in this key locality within the boundary zone between the african and arabian plates the structure and geomorphology of which have been fundamentally misunderstood in the past

mineral phases and facies characterization in metalliferous sediments of atlantis ii deep red sea abstract metalliferous sediments from the atlantis ii deep red sea exhibit significant vertical variations in the composition and distribution of the mineral phases although the sediment facies classified earlier can be recognized in the core some fluctuations exist due to the elemental migration external mineral contribution and diagenetic processes the carbonate minerals constitute considerably thick layers in the sediments and need to be characterized as a separate facies sulfate sulfide sulfate oxide sulfate carbonate and carbonate sulfide associations are considered to have been developed due to mixing of different mineral phases formed under specific conditions either during deposition or after burial in the biogenic material dominant lower sections of the cores most of the mineral phases are either euhedral or subhedral contrary to the massive forms in the middle and upper horizons manganese appears to be mostly concentrated in manganosiderite and manganite phases in the lower sulfide facies only zinc and copper are incorporated in sphalerite and chalcopyrite whereas in other facies no x ray detectable mineral forms of these metals are noticed

early and middle pleistocene faunal and hominins dispersals through southwestern asia abstract this review summarizes the paleoecology of the early and middle pleistocene of southwestern asia based on both flora and fauna retrieved from a series of windows provided by the excavated sites the incomplete chrono stratigraphy of this vast region does not allow to accept the direct chronological correlation between the available sites and events of faunal and hominin dispersals from africa it also demonstrates that hominins survived in a mixed landscape of open parkland with forested surrounding hills in addition the prevailing environmental conditions are not sufficient to explain successful adaptations to new ecological niches away from the african savanna of the bearers of core and flake and the acheulian industries the differences in knapping and secondary shaping of stone artifacts probably reflect the learned traditions of different groups of hominins the current distribution of lithic industries across eurasia is undoubtedly incomplete due to lack of cultural continuities as well as paucity of field research in several sub regions this observation supports the contention that what we view as a constant stream of migrants was actually interrupted many times the continuous occupation of southwestern asia by the makers of the acheulian is in contrast with neighboring regions such as the iranian plateau and eastern europe a more complex model is required to explain the recorded eurasian archaeological cultural mosaic

a dynamic concept for eastern mediterranean circulation and oxygenation during sapropel formation we propose that intermittent bottom water ventilation occurred throughout periods of sapropel deposition and that the recently reported sapropel interruptions represent centennial scale episodes of enhanced frequency intensity of that process in essence the modern high frequency variability in deep water formation affected by climatic variability over the northern basins on seasonal to longer time scales prevailed also at times of sapropel deposition although the overall ventilation state was much reduced this concept is supported by detailed multiple species isotope records for three aegean cores the presence of abundant globorotalia truncatulinoides within especially sapropels s7 and s8 in the western levantine basin observations of three rapid benthic repopulations within sapropel s6 in the deep western levantine basin a report of continuous benthic presence through sapropel s1 at intermediate deep locations offshore libya and further supporting information from the literature in the aegean records concomitant abundance of low oxygen tolerant benthic foraminifera and presence of the more oxyphilic benthic foraminifer uvigerina mediterranea with surface similar 13c values indicate repeated deep water re oxygenation events throughout the deposition of s1 the observations of a continuous benthic presence through s1 offshore from libya imply that no persistent anoxia developed at mid depth levels in that region which is far removed from direct deep ventilation influences the abundance of deep mesopelagic g truncatulinoides through several sapropels from the western levantine basin also suggests the presence of bio available oxygen at many hundreds of meters of depth moreover the rapid intermittent benthic repopulations within sapropels from the deep eastern mediterranean imply that bottom water anoxia was spatially restricted and or of a highly intermittent nature the short time scales of these repopulation events are incompatible with titration of an extensively anoxic water column and subsequent re establishment of water column anoxia we suggest that where anoxic azoic conditions were present they most likely were restricted to a veneer at the sediment water interface the extent of such an anoxic blanket depends on the balance between advective oxygen supply into the deep sea and biological and chemical oxygen demand the demand functions imply a decoupling of oxygenation from water mass advection allowing export production and corg posting rates to the sea floor to delimit the extent of the anoxic blanket in both space and time low productivity regions would develop no anoxic blanket allowing for the observed persistence of deep dwelling planktonic and bottom dwelling benthic faunas

discussion on geological offsets and age constraints along the northern dead sea fault syria journal 167 1001 1008 searle et al 2010 present significant new evidence regarding the eruption chronology of the homs basalt which adjoins the misyaf fault part of the northern dead sea fault zone in western syria their ar ar date of 3 7 0 1 ma for the youngest basalt east of this fault at jebel barshin significantly post dates any previously published hitherto the youngest numerical date for any part of the homs basalt has been 4 8 0 2 ma sharkov et al 1994 searle et al 2010 also report a 4 0 0 1 ma ar ar date for a basalt outlier west of the misyaf fault near the village of kafroun this is mapped ponikarov et al 1963 a as a proximal part of one of the most westerly homs basalt flow units which cascaded southwestward to the mediterranean palaeo coastline around the town of safsafeh where it overlies early pliocene marine sediments e g ponikarov et al 1963 a b 1966 1967 notwithstanding the vagaries and inconsistencies in the site location information provided by mouty et al 1992 the new 4 0 0 1 ma ar ar date is evidently from the same flow unit and possibly even from the same outlier as yielded their 8 1 0 2 ma whole rock k ar date the revision now evident to the numerical age of this flow unit brings it into line with the age constraint from the underlying sediments moreover this revision calls into question all extant dates for the homs basalt from mouty et al 1992 sharkov et al 1994 and butler spencer 1999 all are whole rock k ar dates and so may well be systematically old as a result of the effect of excess argon in phenocrysts see kelley 2002 this conclusion is supported by other new ar ar dates of 6 4 0 1 ma and 5 8

crustal uplift in southern england evidence from the river terrace records abstract much of the past work on the quaternary rivers of northwest europe has been concerned with river terraces which characterise almost every valley while these terraces are undoubtedly striking features of the landscape the incision achieved by quaternary rivers is equally significant in terms of river behaviour and for an understanding of the factors affecting landform development during the quaternary this paper examines the incision achieved during the quaternary by the thames in both its upper and lower catchments and by the hampshire avon in southern england valley incision rates of ca 0 07 0 10 m ka 1 have been identified although in the lower catchment of the thames these have been enhanced by additional incision in response to glacio isostasy and valley shortening a model is proposed in which regional uplift is recognized as the primary cause of incision by these quaternary rivers possible mechanisms for regional uplift are considered

river terrace development in the ne mediterranean region syria and turkey patterns in relation to crustal type it is widely recognized that the optimal development of river terraces globally has been in the temperate latitudes with nw and central europe being areas of particular importance for the preservation of such archives of quaternary environmental change there is also a growing consensus that the principal drivers of terrace formation have been climatic fluctuation against a background of progressive but variable uplift nonetheless river terraces are widely preserved in the mediterranean region where they have often been attributed to the effects of neotectonic activity with a continuing debate about the relative significance of fluctuating temperature glacials interglacials and precipitation pluvials interpluvials research in syria and southern central turkey specifically in the valleys of the tigris and ceyhan in turkey the kebir in syria and the trans border rivers orontes and euphrates has underlined the importance of uplift rates in dictating the preservation pattern of fluvial archives and has revealed different patterns that can be related to crustal type the ne mediterranean coastal region has experienced unusually rapid uplift in the late quaternary the relation between the kebir terraces and the staircase of interglacial raised beaches preserved along the mediterranean coastline of nw syria reinforces previous conclusions that the emplacement of the fluvial terrace deposits in the mediterranean has occurred during colder climatic episodes

implications of sediment flux dependent river incision models for landscape evolution 1 developing a quantitative understanding of the factors that control the rate of river incision into bedrock is critical to studies of landscape evolution and the linkages between climate erosion and tectonics current models of long term river network incision differ significantly in their treatment of the role of sediment flux we analyze the implications of various sediment flux dependent incision models for large scale topography in an attempt 1 to identify quantifiable and diagnostic differences between models that could be detected from topographic data or from the transient responses of perturbed systems and 2 to explain the apparent ubiquity of mixed bedrock alluvial channels in active orogens although certain forms of the various models can be discarded as inconsistent with morphological data we find that the relative intrinsic concavity indices of detachment and transport limited systems defined herein largely dictate whether the various models can be tied to distinctive steady state morphologies preliminary data suggest that no such diagnostic differences may exist and other methods must be developed to test models accordingly we develop and explore differences in the scaling behavior of topographic relief and the extent of detachment versus transport limited channels as a function of rock uplift rate that may allow discrimination among various models further we explore potentially diagnostic differences in the rates and patterns of transient channel response to changes in rock uplift rate in addition to general differences between detachment and transport limited systems our analysis identifies an interesting hysteresis in landscape evolution hybrid channels at the threshold between detachment and transport limited conditions are expected to act as detachment limited systems in response to an increase in rock uplift rate or base level fall and as transport limited systems in response to a decrease in rock uplift rate especially during postorogenic topographic decline the analyses presented set the stage for field studies designed to test quantitatively the various river incision models that have been proposed

long term fluvial archives in nw france response of the seine and somme rivers to tectonic movements climatic variations and sea level changes the seine and the somme are the two main rivers flowing from northwestern france into the channel during the pleistocene cold stages both rivers were tributaries of the river manche which was exporting sediments into the central deeps of the channel the river seine has a very well developed terrace system recording incision that began at around 1 ma the same age is proposed for the beginning of the main incision in the somme valley on the basis of morphostratigraphy pedostratigraphy palaeontology palaeomagnetism and esr datings the uplift rate deduced from analysis of the seine and somme terrace systems is of 55 to 60 m ma since the end of the lower pleistocene the response of the two rivers to climatic variations uplift and sea level changes is complex and variable in the different parts of the river courses for example the evolution of the lower seine system is influenced by uplift and climate changes but dominated by sea level changes in the middle seine the system is beyond the impact of sea level variations and shows a very detailed response to climatic variations during the middle and upper pleistocene in a context of uplift the somme valley response appears to be more homogeneous especially in the middle valley where the terrace system shows a regular pattern in which incision occurs at the beginning of each glacial period against a general background of uplift nevertheless the lower somme valley and the palaeo somme in the channel area indicate some strong differences compared with the middle valley influence of sea level variations and probably differences in rates of tectonic uplift between the channel and the present continent the differences in the responses of the two river valleys during the pleistocene are related to differences in the size of the fluvial basins to the local tectonic characteristics to the geometry of the platform connected to the lower parts of the valleys and to the hydrodynamic characteristics of each river finally it is shown from these examples that the multidisciplinary study of pleistocene rivers is a very efficient tool for the investigation of neotectonic activity

first indications of high slip rates on active reverse faults nw of damascus syria from observations of deformed quaternary sediments implications for the partitioning of crustal deformation in the middle eastern region recent research on rates of crustal shortening within the palmyra fold belt pfb in syria has drawn attention to the possibility that reverse faults near the city of damascus which adjoins the sw pfb have significant slip rates we infer that the damascus fault directly adjacent to the city has developed a throw of 2500 m and report the discovery of the en echelon bassimeh fault with a throw of 1000 m this fault being revealed by warping of the local bedrock and of a terrace of inferred late pleistocene age of the river barada we estimate that this set of faults became active circa 0 9 ma synchronous with changes to the pattern of faulting previously reported farther southwest in the northern jordan valley vertical slip rates on the bassimeh and damascus faults of 1 1 and 2 8 mm a 1 respectively are thus estimated we also infer that large historical earthquakes previously attributed to left lateral faulting farther west on the dead sea fault zone dsfz probably occurred on this set of reverse faults these faults thus represent a significant hazard to the city of damascus our observations indicate that as much as half of the northward motion of the arabian plate relative to the african plate may be absorbed by crustal shortening within the pfb potentially explaining the low slip rate recently measured geodetically on the northern dsfz in western syria

uplift driven valley incision and river terrace formation in southern england outside the limits of middle pleistocene glaciation the river basins of southern england contain long cenozoic terrestrial sedimentary records of greatest importance are the river terrace sequences which contain biostratigraphical and sedimentary evidence that testifies to the high amplitude climatic changes of the quaternary however trends in valley development cannot easily be accommodated within the framework of quaternary climatic change it is argued in this paper that episodic incision and terrace development result from uplift a consequence of the interplay between continuing alpine orogenic movements and erosion driven isostasy using a simple linear model height age an uplift rate of ca 7 cm ka 1 is estimated for the terrace sequence in the upper thames valley this preliminary model is evaluated using the records of adjacent basins 1997 john wiley sons ltd

pleistocene evolution of the nile valley in northern upper egypt abstract in the el minia district of northern upper egypt the pleistocene deposits of the nile valley include early pleistocene conglomerates of the armant formation and middle pleistocene sands of the qena formation these sediments are exposed along both sides of the valley in terraces at different heights unconformably overlying eocene limestones field observations suggest that the conglomerate facies of the armant formation was deposited in proximal and mid alluvial fans the sands of the qena formation are differentiated into two facies a cross bedded sandstone representative of alluvial fan braided stream environments and a facies of sand interbedded with mud that may have been deposited by a meandering river the heavy minerals of the armant formation are markedly different from those of the qena formation suggesting derivation from different sources surface textures of quartz grains from the qena sands observed by sem exhibit chemical features attributed to a fluviatile origin sand from the armant formation is characterized by mechanical and chemical surface textural features that suggest original aeolian derivation followed by later fluvial sedimentation

late cenozoic regional uplift and localised crustal deformation within the northern arabian platform in southeast turkey investigation of the euphrates terrace staircase using multidisciplinary techniques we present the results of detailed field investigations of the fluvial succession exposed along the euphrates valley adjoining the ataturk dam in the northern part of the arabian platform within se turkey this work which has used differential gps surveying to obtain accurate heights of deposits and shuttle radar topographic mission imagery for location purposes has included documentation of many fresh sections exposed by quarrying the work has been supplemented by unspiked kar dating of late middle miocene to late miocene basalt flows which are widespread in the region providing a chronology for the early stages of development of this river system following regional emergence above sea level in the early middle miocene for example beside the ataturk dam lake at siverek iskelesi basalt dated to 10 24 0 22 ma 2 caps a polymict euphrates gravel some 80 m above the modern river this is the oldest euphrates terrace currently recognised however amounts and rates of fluvial incision are shown to vary across the northern arabian platform in a complex manner due to the interaction between regional uplift and localised vertical crustal motions caused by slip on active reverse faults beneath anticlines the study reach downstream of the ataturk dam includes the footwall of one such fault beneath the bozova anticline we estimate that the resulting rate of localised subsidence superimposed onto the regional uplift that has also been occurring has been 0 01 mm a 1 during the present phase of crustal deformation which began at 3 7 3 6 ma but was higher maybe 0 03 mm a 1 during the previous phase which began at 6 ma when the pattern of plate motions in the surrounding region was different a large palaeo lake centred north of the present study region around the city of adiyaman is inferred to have existed during this 6 ma to 3 7 3 6 ma phase of plate motion apparently because the relatively rapid localised hanging wall uplift on the northern flank of the bozova anticline dammed the euphrates valley near the site of the modern ataturk dam the uppermost part of a thick fluvial aggradation west of the euphrates near karababa bridge inferred to date from around the mid pliocene reaches 100 m above the modern river and after correction for an estimated 30 m of localised subsidence and by 50 m for subsequent downstream lengthening of the euphrates channel indicates 180 m of subsequent regional uplift the euphrates then incised to within 20 m of its present level by the mid early pleistocene then a switch to regional subsidence accompanied the deposition of a second thick fluvial aggradation the top of which is 70 m above the modern river subsequent renewed regional uplift following the mid pleistocene revolution has resulted in the development of a succession of fluvial terraces typically inset into these older aggradations which are correlated with the cold stages of milankovitch climate cycles the early part of the euphrates chronology constrained mainly by the disposition of basalt flows indicates 800 m of regional uplift since the early middle miocene of which an estimated 330 m is masked by the subsequent downstream lengthening of the river components of localised uplift and subsidence caused by slip on reverse faults beneath anticlines are superimposed onto this regional pattern the hanging wall uplift being much larger in one case roughly five times larger than the footwall subsidence our results provide for the first time detailed documentation of the complex development of the euphrates valley in se turkey during the late cenozoic due to the interaction between regional uplift and localised crustal deformation this work also demonstrates the benefits of applying multidisciplinary techniques to investigate an important but hitherto poorly documented river system

arabia eurasia collision and the forcing of mid cenozoic global cooling the end of the eocene greenhouse world was the most dramatic phase in the long term cooling trend of the cenozoic era here we show that the arabia eurasia collision and the closure of the tethys ocean gateway began in the late eocene at 35 ma up to 25 million years earlier than in many reconstructions we suggest that global cooling was forced by processes associated with the initial collision that reduced atmospheric co2 these are 1 waning volcanism across southwest asia 2 increased organic carbon storage in paratethyan basins e g black sea and south caspian 3 increased silicate weathering in the collision zone and 4 a shift towards modern patterns of ocean currents associated with increased vigour in circulation and organic productivity

late cenozoic landscape development and its tectonic implications for the guadalhorce valley near alora southern spain abstract landscape evolution is the result of a variety of geomorphological processes and their controls in time in southern spain tectonics climate and sea level fluctuations have been some of the main variables controlling long term late cenozoic landscape evolution in the guadalhorce valley malaga geomorphological reconstructions can be undertaken using sedimentary evidence from marine and fluvial deposits as well as erosional evidence such as terrain form and longitudinal profile analysis data are obtained and analysed from the upper miocene to present these allow reconstructions which add information and constraints to the uplift history and landscape development of the area main sedimentation phases are the late tortonian early pliocene and pleistocene important erosional hiatus are found for the middle miocene messinian and late pliocene to early pleistocene these phases of erosion and sedimentation resulted in a relative large and elongated tortonian marine valley filled with complex sedimentary structures next a prolonged stage of erosion of these deposits and incision of the major valley system took place during the messinian in the pliocene a short palaeo guadalhorce in a narrow and much smaller valley existed this valley was partly filled with marine sediments and prograding fan delta complexes during the pleistocene a wider and larger incising river system resulted in rearrangements of the drainage network evaluating the uplift history of the area we found that rates of tectonic activity were higher during the tortonian messinian and upper pleistocene while tectonic activity was lower during the pliocene relative uplift rates for the study area range for the messinian between 160 and 276 m ma 1 for the pliocene between 10 and 15 m ma 1 and for the pleistocene between 40 and 100 m ma 1

uplift driven valley incision and climate controlled river terrace development in the thames valley uk abstract the sequence of terraces of the river thames in southeast england has previously been shown to span the period from the earliest pleistocene to the present this terrace sequence contains biostratigraphical and sedimentary evidence that testifies to the high amplitude climatic changes of the quaternary large scale fluvial incision resulting in basin wide terrace formation appears to have been concentrated at the warming limbs of the major climatic glacial interglacial cycles when sediment supply was greatly reduced this incision and subsequent valley floor widening created the accommodation space for the later aggradation of the terrace sediments during the following warm cold transitions and during the cold stages when high sediment supply conditions prevailed although the timing of terrace aggradation may be controlled by climate change the progressive valley incision recorded by terrace staircases cannot easily be explained in terms of quaternary climatic change alone and recently developed models suggest that long term incision by the thames has been driven by uplift this paper presents an overview of the available terrace data and tabulates incision amounts and rates between key stratigraphic horizons superimposed upon these broad changes revealed by the complex internal sedimentary architecture of many terrace sediments are the geomorphological system responses to both higher frequency climate driven changes and more localized intrinsic fluvial system adjustments

fluvial networks of the iberian peninsula a chronological framework abstract knowledge of the evolution of spanish fluvial networks has improved during recent years as more river systems have been studied and more geochronological data has become available however the chronological framework is a major issue as the range of applications is limited by methodological constraints and spatial coverage is sparse integration of absolute dating methods with biostratigraphy and palaeomagnetism permits the recent evolution of these river systems to be reviewed the timing of incision from the late neogene to the present varies between the major iberian fluvial systems depending on the substrata and tectonic settings early pleistocene and older fluvial sequences in the core areas of the iberian peninsula provide a more extensive record of fluvial evolution and are better preserved than the terrace flights in the coastal lowlands middle pleistocene sequences are well developed in most of the major river systems in iberia particularly those of the tajo guadalquivir and aguas river and frequently represent the principal climatic cycles of that period although tectonic and sea level effects can also be seen for late pleistocene to holocene times the scheme becomes more complex our review suggests that each river system has responded differently to local and regional climate control glacial and periglacial processes in headwaters in high mountain areas glacio eustatic sea level changes and local and regional tectonic patterns

an obliquity controlled early pleistocene river terrace record from western turkey investigation of the pleistocene sequence of the gediz river western turkey has revealed a record of early pleistocene river terraces eleven terraces spanning the interval from 1 67 to 1 245 million years ago mis 59 37 are preserved beneath basaltic lava flows the high number of terraces over this short time period reflects high frequency sedimentation incision cycles preserved due to the fortuitous combination of relatively high uplift rates 0 16 mm yr 1 and progressive southwards valley migration comparison of this record with odp967 from the eastern mediterranean basin suggests a link between the production of terraces and obliquity driven 41 000 year climate cycles in the early pleistocene

saalian supercycle mindel riss interglacial and milankovitch s dating abstract there are five pleistocene glacial interglacial cycles recorded in deep sea sediments from the last half million years but only two classic interglacials are recognized on land the dilemma stems from the different understanding and identification of glacials and interglacials in the geologic records on land and in the ocean only those intervals of warm climate that followed a major southward ice sheet advance and were accompanied by a deep penetrating oceanic transgression were recognized in their type areas of northern europe as true interglacials only those ice advances which left moraines farther south than younger ones were recognized as glacials in contrast all intervals reflecting exceptionally low global ice volume high sea level and warm sea surface are taken as interglacials in the deep sea record classic subdivisions are aligned with the glacial interglacial cycles of marine isotope stage stratigraphies by proposed higher order units called supercycles sc bracketed by superterminations st the saalian supercycle sc2 includes glacial cycles c d and e composed of marine isotope stages mis 6 7 8 9 10 and 11 the units mis 7 to mis 11 correspond to the great gross interglacial estimated from the early geologic considerations to be about 240 millennia long penck and bruckner 1909 die alpen im eiszeitalter vols 1 3 christian herman tauchnitz leipzig and determined from astronomic computations to last 235 millennia milankovitch 1941 kanon der erdbestrahlung und seine anwendung auf das eiszeitenproblem academie royale serbe editions speciales section des sciences mathematiques et naturelles tome cxxxiii stamparija mihaila curcica beograd 633pp the current high precision radiometric dating fully confirms the accuracy of milankovitch s determination and the pivotal role of orbital mechanisms in pleistocene climate change

mediterranean pluvial periods and sapropel formation over the last 200 000 years abstract three mediterranean deep sea cores have been studied to reconstruct the hydrological conditions at the time of deposition of interglacial and glacial sapropels during the time interval 200 60 kyr bp the isotopic and sea surface temperature records of planktonic foraminifera were used to estimate the oxygen isotopic composition of surface water w in the tyrrhenian sea and levantine basin our results show a strong w salinity decrease in both basins associated with each sapropel these w decreases reflect a drastic change in the local freshwater budget and were comparable to that observed during the last sapropel s 1 centred at ca 8 kyr bp a strong precipitation increase transformed the whole mediterranean sea into a non concentration basin the low surface salinity was responsible for the water column stratification while nutrients brought in by the runoff enhanced productivity it resulted in a significant reduction in the rate of deep water oxygenation and sapropel formation in the eastern basin in addition the mediterranean sea 18 o record is very similar to that of the bay of bengal as the latter is very sensitive to the summer monsoon rain this similarity suggests that both glacial and interglacial sapropels result from enhanced monsoon like precipitation due to an increase in summer insolation driven by precession variations

interpreting the response of a dryland river system to late quaternary climate change abstract a u series calcrete chronology has been constructed for three late quaternary terrace units termed the d1 d2 and d3 terraces in age descending order from the rio aguas river system of the sorbas basin southeast spain the d1 terrace formed between 30 300 4400 year bp and 12 140 360 year bp correlating well with the last glacial maximum when rates of sediment supply would have increased greatly because of higher rates of weathering reduced vegetation cover and weak soil development the d2 terrace formed between 12 800 1100 year bp and 9 600 530 year bp correlating well with the younger dryas event the d3 terrace could only be poorly constrained to the early holocene and no unequivocal cause could be assigned to this period of aggradation the sedimentology and geomorphology of the d2 terrace suggests however that the aggradation of this unit was a response to diapirism karstic processes occurring within the underlying messinian gypsum strata and the subsequent damming of the aguas system therefore despite its coincident occurrence with the younger dryas aggradation of the d2 terrace is unrelated to climate change the style of this response controlled predominantly by the characteristics of the underlying bedrock makes correlating the terrace record of the aguas with other systems in the mediterranean unreliable this study therefore highlights the problems of correlating fluvial sequences in regions of variable tectonics climatic history and bedrock geology and emphasises the need to properly understand the main controls on individual fluvial systems before any attempt is made to correlate their depositional histories

the mid pleistocene climate transition onset of 100 ka cycle lags ice volume build up by 280 ka the mid pleistocene climate transition mpt is the complex climatic change which brought the late pleistocene ice ages we explore the mpt in the time and frequency domains by new methods of time series analysis high resolution oxygen isotope records reveal that the ice volume related increase in 18o mean amplitude 0 29 0 05 1 transition midpoint 922 12 ka duration 40 9 ka significantly preceded the abrupt increase in the amplitude of the 100 ka cycle at 641 9 ka this finding can be quantitatively simulated using a simple ice bedrock model in which due to the additional ice the calving threshold is exceeded the simulated calving events prior to 650 ka are separated by 77 ka whereas after 650 ka they occur pseudo periodically with a mean period of nearly 100 ka the cause for the delay of the 100 ka calving cycle was not a slow bedrock relaxation rather the coincidental combination of insolation existing ice mass and bedrock depression