cyclostratigraphy of lower triassic terrestrial successions in the junggar basin northwestern china abstract the astrochronology for the early triassic has been constructed from well preserved marine successions however astronomical analyses of terrestrial strata have continued to be rare and problematic physical logs natural gamma ray logging data from two wells in the junggar basin northwestern china cover the entire lower triassic terrestrial baikouquan formation and have been shown to be a powerful tool in cycle analysis therefore these logs offer an excellent opportunity to detect astronomically forced sedimentation in a terrestrial setting from mid to high latitudes power spectral analysis revealed that the sedimentary cycles had wavelengths of 31 3 35 9 m 8 4 10 0 m 4 0 4 6 m and 4 0 m these are interpreted to correspond to the orbital eccentricity cycles of 405 kyr and 100 kyr and to the obliquity cycles of 51 kyr and 34 kyr respectively we thus established an astronomical time scale for the studied interval assuming that the 31 3 35 9 m cycles represent the 405 kyr eccentricity cycles this astrochronology indicated that the duration of the baikouquan formation was 2 0 0 1 myr statistical evaluations of optimal sediment accumulation rates using the correlation coefficient approach showed that the rates of the investigated successions were approximately 6 0 12 0 cm kyr orbitally controlled climate change was the major dynamic mechanism for the formation of early triassic fan delta successions in the junggar basin

correlation of fluvial sequences in the mediterranean basin over the last 200 ka and their relationship to climate change macklin mark fuller i c lewin j maas g a 2002 correlation of fluvial sequences in the mediterranean basin over the last 200 ka and their relationship to climate change quaternary science reviews 21 14 15 pp 1633 1641 rae2008

climatic controls on late pleistocene alluvial fans cyprus alluvial fans are commonly associated with tectonically active mountain ranges and tectonism is frequently held responsible for abrupt coarsening and cyclical sedimentation of alluvial fan sequences whilst it is accepted that tectonism provides the opportunity for alluvial fan development through the creation of topography increasing gradients of fluvial systems supplying sediments and creating accommodation for the storage of sediment flux the role of climate in fan development is frequently neglected the hypothesis that climatically controlled events can produce recognisable sedimentary signatures in alluvial fan deposits is tested in the active supra subduction zone setting of the late pleistocene of southern cyprus this study demonstrates through architectural analysis and the reconstruction of palaeoflood hydrology a recorded pattern of increasing and decreasing palaeoflow dynamics with switches from a wetter to drier mode clearly exhibited by changes in the sedimentology of the fan at the present day cyprus has a semi arid climate and is influenced by a strongly seasonal rainfall pattern largely restricted to the winter months plus rare occurrences of summer cyclones however at precession minima increased activity of western mediterranean depressions produces wetter summers using inference we propose that longer term increases in rainfall increased river discharge as recorded in the fan palaeoflood hydrology and occurred at minima in the precession these periods correlate with the deposition of conglomeratic channels and open framework gravels drier periods are exhibited by sandier braided fluvial deposits shorter term or seasonal change is recorded in the form of 2nd and 3rd low order bounding surfaces this increased activity of mediterranean summer depressions increased precipitation to the wider levantine area and was coincident with increased intensity of the north african and indian ocean sw monsoons the resultant increase in river discharges at precession minima from both the nile and the wider levant resulted in the formation of sapropels in the eastern mediterranean and is recorded as wet periods in speleothem deposits in the soreq and peqiin caves of israel the predominant control of sedimentation on the late pleistocene alluvial fans of southern cyprus was climate

temporal buffering of climate driven sediment flux cycles by transient catchment response abstract the marine sedimentary record can exhibit a systematic cyclicity that is consistent with climate variability driven by milankovitch scale forcing milankovitch band cyclicity is widely interpreted in the hemipelagic and pelagic sediments of the marine realm and in terrestrial paleoenvironments has been observed in lacustrine sediments soils and river floodplain successions it remains unclear however if and how mountain catchments as a primary sediment source respond to these high frequency 6 yr climatic cycles and whether particulate sediment flux signals can be expected to be recorded in the clastic sedimentary record of adjacent basin fills recent field and theoretical studies suggest that mountain catchments respond transiently to high frequency forcing and so sediment discharge from the catchment is a non linear function of forcing variables using a catchment basin model we demonstrate that climate driven cyclicity in particulate sediment discharge is strongly damped when the period of climate variability is shorter than the response timescale of the eroding landscape given that the response timescale of landscapes is of the order of 10 6 yr and that milankovitch driven climate cyclicity is of the order of 10 4 10 5 yr it is likely that climate driven perturbation of upland catchments at these periods will be strongly damped by transient landscape behaviour our results therefore suggest that stratigraphy built by particulate fluxes from upland catchments and long term trends in the sediment delivery to the ocean may be relatively insensitive to short term climate variability

the miocene pakhna formation southern cyprus and its relationship to the neogene tectonic evolution of the eastern mediterranean abstract the miocene pakhna formation is interpreted as relating to onset of the present northward subduction of the african plate beneath cyprus and is thus critical to understanding of the neogene evolution of the eastern mediterranean basin following a perios of deep water pelagic chalk deposition in the late eocene and oligocene upper lefkara fm the pakhna formation records heterogeneous mainly carbonate sedimentation the pakhna formation is bounded by the limassol forest block an uplifted ophiolitic terrain to the north and by the akrotiri high a ridge of exotic mesozoic lithologies to the south two sub basins maroni in the e and khalassa in the w within the pakhna formation were separated by the wnw ese trending yerasa lineament located near the s margin of the ophiolite in most areas the pakhna formation overlies the lefkara formation disconformably the succession begins with deep water pelagic carbonates and shows increased input of shallow water bioclastic and terrigenous sediment upward during the early to mid miocene the ophiolitic terrain to the n was uplifted deformed and eroded followed by marine transgression and patch reef development in the tortonian late miocene ophiolite derived clastics were mixed with shallow water bioclastic sediment reworked in a high energy coastal setting and transported downslope within channels into the basin accumulating as massive sands debris flows and calciturbidites in the maroni sub basin localised debris aprons prograded into a pelagic carbonate environment to the se further west in the khalassa sub basin little uplift occurred along the basin margins and redeposited sediment was mainly bioclastic contrasting sediment including chert was derived from the allochthonous mamonia complex exposed on the akrotiri high to the s and its possible offshore extension bioclastic sediment including reef talus was also derived from an intrabasinal high in the khalassa sub basin eventually normal marine deposition was ended by the messinian salinity crisis

geomorphology internal structure and evolution of alluvial fans at motozintla chiapas mexico abstract alluvial fans and terraces develop in diverse regions responding to different tectonic and climatic conditions the motozintla basin is located in the state of chiapas southern mexico and has an e w orientation following the trace of the left lateral polochic fault the evolution of the motozintla basin and the alluvial plain is related to several factors such as fault movement intense erosion by hydrometeorological events and anthropogenic activity this study presents the geomorphology of the alluvial plain that between the villages of motozintla and mazapa de juarez exposes 31 alluvial fans 5 hanging terraces and 13 ramps fourteen of these alluvial fans have been truncated by the polochic fault exposing maximum uplifts of 12 m the internal structure of truncated fans consists of single massive beds monolithologic fans or stacked beds polygenetic fans the fans stratigraphy is made of debris flow deposits separated by paleosols and minor hyperconcentrated flows fluviatile beds and pyroclastic fall deposits the reconstruction of the stratigraphy assisted by radiocarbon geochronology suggests that these fans have been active since late pleistocene 25 ka to the present this record suggests that at least 10 events have been recorded at the fan interior during the past 1840 years one of these events at 355 65 14 c yrs bp cal yrs ad 1438 to 1652 can be correlated across the fans and is likely associated with an extreme hydrometeorologic event the presence of a 165 60 14 c yrs bp cal yrs ad 1652 1949 debris flow deposit within the fans suggests that movement along the polochic fault formed the fans scarp afterwards in fact a historic earthquake along the fault occurred east of motozintla on july 22 1816 with a m w of 7 5 7 75 recent catastrophic floods have affected motozintla in 1998 and 2005 induced by extreme hydrometeorological events and anthropogenic factors therefore scenarios for motozintla involved several types of mass movement processes that pose a serious hazard and threat to the inhabitants of the region

measuring alluvial fan sensitivity to past climate changes using a self similarity approach to grain size fining death valley california the effects of climate change on eroding landscapes and the terrestrial sedimentary record are poorly understood using mountain catchment alluvial fan systems as simple analogues for larger landscapes a wide range of theoretical studies numerical models and physical experiments have hypothesised that a change in precipitation rate could leave a characteristic signal in alluvial fan sediment flux grain size and down system fining rate however this hypothesis remains largely untested in real landscapes this study measures grain size fining rates from apex to toe on two alluvial fan systems in northern death valley california usa which each have well exposed modern and ca 70 ka surfaces and where the long term tectonic boundary conditions can be constrained between them these surfaces capture a well constrained temporal gradient in climate a grain size fining model is adapted based on self similarity and selective deposition for application to these alluvial fans this model is then integrated with cosmogenic nuclide constraints on catchment erosion rates and observed grain size fining data from two catchment fan systems to estimate the change in sediment flux from canyon to alluvial fan that occurred between mid glacial and modern interglacial conditions in a fan system with negligible sediment recycling an approximately 30 decrease in precipitation rate led to a 20 decrease in sediment flux and a clear increase in the down fan rate of fining supporting existing landscape evolution models consequently this study shows that small mountain catchments and their alluvial fan stratigraphy can be highly sensitive to orbital climate changes over 105 year timescales however in the second fan system it is observed that this sensitivity is completely lost when sediment is remobilised and recycled over a time period longer than the duration of the climatic perturbation these analyses offer a new approach to quantitatively reconstructing the effects of past climate changes on sedimentation using simple grain size data measured in the field this article is protected by copyright all rights reserved

climatic and tectonic controls on alluvial fan and axial fluvial sedimentation in the plio pleistocene palomas half graben southern rio grande rift abstract six steep 0 6 4 3 short radial length 1 5 5 km deeply incised pliocene to early pleistocene paleofans and associated axial fluvial strata are preserved adjacent to the footwall of the palomas half graben in the southern rio grande rift two different scales of interbedding of lithofacies are evident in the exposed basin fill sediment the footwall derived alluvial fan strata are arranged into 3 10 m thick cyclothems representing three events 1 development of calcic paleosols that were contemporaneously or subsequently truncated by channels up to 4 m deep 2 infilling of channels by turbulent flow horizontally bedded and cross bedded conglomerates and 3 deposition of hyperconcentrated flow pebbly sandstones these cyclothems probably resulted from paleoclimatic changes on the scale of 150 kyr on a larger geographic and temporal scale the axial river ancestral rio grande which primarily deposited cross bedded pebbly sand experienced kilometer scale lateral movement toward the footwall block resulting in one thick 80 m axial fluvial lithosome in the northern part of the basin and two or three thinner 8 25 m axial fluvial lithosomes in the south a protracted period of fault movement and consequent basin tilting was the probable driving force behind lateral movement of the river and toe cutting of the fans by the river was the dominant process

framework dilation winnowing and matrix particle size the behavior of some sand gravel mixtures in a laboratory flume abstract a series of experiments have been carried out in a laboratory flume to simulate the conditions in a gravel bed river with a supply of finer sand size material under flow conditions where some or all of the material is in motion the experimental program incorporated three sets of experiments 1 where flows were just above the theoretical threshold for entrainment of the sand 2 where flows were at the theoretical threshold for entrainment of the gravel and 3 where flows were well above the threshold for both transport of sand and gravel particle movements were monitored using a new digital photographic and image analysis method that allows detection of motions over periods as small as 0 04 s the results show that where flows are capable of moving only the finer material grain size of the matrix is controlled by a combination of winnowing and particle overpassing under these conditions the grain size of the fine material trapped in the pore spaces of the gravel declines downstream once the gravel becomes entrained the processes are very different just before the surface gravel layer is eroded the framework lifts and dilates causing matrix particles to move down into subsurface pores under these conditions matrix grain size increases downstream because larger matrix particles are more likely to become stuck in pore throats and entrained with the gravel framework the dilation process is hitherto unreported and has many implications for sediment transport it appears that lift not drag is the important force during the early stages of entrainment and as a result fine matrix particles can be less mobile than those of the coarser framework

climatic versus tectonic controls of fan sequences lessons from the dead sea israel tectonic activity is commonly held responsible for abrupt coarsening of alluvial fan sequences and the role of climate is often relegated the pleistocene fans of the dead sea rift indicate clearly the problems of differentiating the sedimentary signatures of climatic and tectonic adjustments in a closed lake basin exposures are excellent the rivers are currently incising in response to the low lake levels of the holocene producing cliffs 50m high these reveal an interdigitation of lake deposits dominantly fine grained carbonates and the coarse river gravels which characterize the fan deposits the bounds of each facies are sharp river sediments are superimposed on lake sediments with little evidence of either reworking or loading in turn aragonite crusts are draped over alluvial gravels indicating the sudden return of still water conditions neither can be explained by gradual adjustment of the hinterland river system after tectonic shock instead it is clear that the coarse alluvium was deposited by discrete high magnitude floods that occurred only sporadically because of the infrequent nature of rainfall in this arid environment in interpreting basin development in ancient settings it is always tempting to assume that coarse deposits are indicative of tectonism however the dead sea fans demonstrate that climate is just as likely to be responsible for the conglomerates in a sedimentary sequence

translocated plio pleistocene drainage systems along the arava fault of the dead sea transform abstract geomorphic and sedimentologic field studies and analyses of landsat 5 images and topographic maps indicate 15 km of left lateral displacement of a pliocene large stream and alluvial fans along the dead sea transform in southern israel and jordan in the central arava valley a rift valley located along the transform there is a notable discrepancy between the number and location of the feeding drainage basins within the eastern margins of the arava valley and those of the alluvial fans and the cross rift large stream a few of these large alluvial fans lack any feeding drainage basin furthermore east of the large stream there is no drainage basin that could have fed it these discrepancies between the physiography locations sizes and lithological compositions of the feeding drainage basins and of the alluvial fans can be explained by 15 km of left lateral movement since the late pliocene or the early pleistocene along the arava dead sea segment of the transform this is one of the largest displacements of a landform and surficial alluvial deposit in the world however the resulting average long term rate of movement is relatively small 0 3 0 75 cm year

late quaternary uplift of the troodos ophiolite cyprus uranium series dating of pleistocene coral in an attempt to constrain the timing and mode of tectonic uplift of the classic troodos ophiolite colonial corals were collected from quaternary littoral raised terraces in coastal southern cyprus and dated using the uranium series disequilibrium method a total of 28 samples of cladocora caespitosa were collected at five localities from the 8 11 m high and 3 m high marine terraces the corals yield systematic ages of 185 192 ka ka 103 yr and 116 130 ka for the 8 11 m and 3 m terraces respectively when correlated with the global oxygen isotope stages the results suggest that southern cyprus was uplifted by 18 m during the past 185 192 ka as a single tectonic entity of this uplift 13 m took place between 130 and 185 ka at 24 cm ka and a maximum of 6 m of uplift at 5 cm ka took place over the past 116 ka but with some evidence of coastal subsidence in more recent time an exception the extreme southeast of cyprus cape greco was perhaps uplifted faster during the past 141 ka at a rate of 12 cm ka

the development of a laterally confined laboratory fan delta under sediment supply reduction abstract in previous fan delta experiments the effect of lateral confinement was generally ignored as these fans were usually unconfined with semiconical geometries however in gorge areas fan development is usually laterally confined by valley walls this study investigates autogenic processes of fan deltas in a laterally confined experimental tank the experiment is divided into three phases the sediment supply is held constant within each phase so the autogenic processes of the fan are separated from the allogenic forcings results indicate that laterally confined fan deltas have higher progradation and aggradation potential more regular channel braiding and more even transverse sedimentation than unconfined fans besides responses of fan deltas to sediment supply reduction are investigated in this research at the initiation of the second and third phases sediment feed rates are instantaneously reduced so that the allogenic forcings are predominant observations show that under sediment supply reduction channelization on fan deltas are more pronounced and durations of the fluvial cycles are longer the adjustment of fan morphology becomes slower as the self regulation capacity of the fan decreases with reduced sediment supply

climate environment and stratigraphy of the last pleistocene glacial stage in poland abstract the aim of the paper is to present general characteristics of the climate in poland during the vistulian weichselian expressed by changes of its continentality during warm and cold intervals this last glacial stage in poland is commonly subdivided into early vistulian mis 5d a lower plenivistulian mis 4 interplenivistulian mis 3 and upper plenivistulian and late vistulian mis 2 main climatic features of this glacial stage could be reconstructed based on compilation from published data concerning characteristics of glacial fluvial and aeolian sedimentary environments geomorphology analysis of indicator plant species coleoptera and geographical distribution of periglacial structures these data were indicative especially for evaluation of mean temperature of the warmest and the coldest months but could be also helpful in determination of drier intervals and some aspects of general atmospheric circulation paleoclimatic characteristics of the last glacial stage from the territory of poland were put into the european context during the early vistulian in eastern poland higher continentality was characteristic for interstadials amersfoort brorup and odderade and was considerably lower during the intervening colder stadials herning a cooling between amersfoort and brorup rederstall among the interstadials the most continental climate occurred during brorup similar continentality as at present considerably less during amersfoort and the least during odderade a decreasing trend of continentality for the cold stadials of the early weichselian eastwards in europe could result from a remarkably less dynamic gulf stream in the north atlantic when the ocean was covered with vast sea ice during winters whereas the adjoining continent was occupied by permafrost and the atmospheric circulation was presumably driven also by the scandinavian ice sheet

the depositional conditions of the fluvio aeolian succession during the last climate minimum based on the examples from poland and nw ukraine abstract the object of the study was the fluvio aeolian sedimentary succession in eight sites located in the central part of the european sand belt in poland and nw ukraine based on the lithofacies pedological and morphoscopic analyses the analyses of frost structures and grain size as well as the tl ir osl and 14 c dating three lithofacies complexes deposited at the turn of the weichselian and holocene were documented the fluvial complex was deposited in the pleniglacial within a sandbed braided river which in the final stage of deposition of the complex was transformed into an anastomosing river these rivers functioned in continuous permafrost coverage the fluvio aeolian complex was the result of aeolian deposition and fluvial redeposition resulting from the degradation of continuous permafrost at the turn of the pleni and late glacial these processes operated in the areas abandoned by regular flow the aeolian complex was accumulated following the development of aeolian sand forms sandy and silt covers as well as parabolic and longitudinal dunes after the complete degradation of permafrost at the end of the late glacial and holocene improving climatic conditions were expressed by the presence of fossil levels of initial gley soil in the roof of the fluvio aeolian complex as well as poorly developed podzolic and colluvial soils in the aeolian complex

river incision and terrace formation in the late cenozoic of europe abstract late cenozoic environmental changes which affected european rivers are reviewed focusing especially on those of mid pleistocene times c 1 2 0 8 ma or around mis 22 and thereafter these involved dominating but fluctuating cold climate periglacial conditions shorter but major episodes of glaciation and brief interglacials there were also related sea level and tectonic responses the known history of european rivers in this period is individually varied but is predominantly marked by multiple stages of episodic incision the form of which changed in style at around the mid pleistocene transition it is suggested that the nature of climatic oscillations the dating of incision episodes and the processes that achieve this incision are as yet insufficiently understood fluvial process studies suggest that the onset of incision may broadly relate to changes in slope discharge sediment load and calibre and bedrock erodibility and these may all have been transformed as the direct or indirect result of mid pleistocene climatic changes common properties of basal sediments on strath terraces suggest that it was during the extended but variable cold stage episodes that both valley deepening and lateral widening occurred and that climatic change was the principal driver of episodic deep valley incision

an experimental study of the effects of base level change on fluvial coastal plain and shelf systems abstract several of the concepts of sequence stratigraphic models were tested by experiments in a large flume using different gradients for successive runs a physical model of a fluvial drainage basin coastal plain continental shelf and continental slope was constructed in all experiments initial gradients of the coastal plain and shelf were identical systematic raising and lowering of the water surface simulated the changes in relative sea level i e base level that are similar to most sequence stratigraphic models base level changes significantly affected the shelf area but they had little effect on the fluvial drainage basin during base level falls fluvio deltaic progradation occurred fluvial aggradation occurred only during periods of base level stillstand or rise because of the slow rate of head ward erosion of incised valleys a significant time gap existed from the time base level first fell below the shelfbreak and the development of a cross shelf bypass valley during this lag time deposition occurred on the exposed shelf to form a fluvial braid plain concurrently channels developed at the shelfbreak and grew by headward erosion at various rates continuous incision and widening of these channels formed valleys these valleys were not linked directly to the main drainage basin unt l ultimately one captured the flow from that drainage at that point other valleys were abandoned and ceased to grow during the subsequent base level rise the single large cross shelf valley filled with coarser sediments while the other valleys partially filled with finer suspended load sediments the main cross shelf valley also supplied coarser sediments to the slope

timing and hydrological conditions of sapropel events in the eastern mediterranean as evident from speleothems soreq cave israel this paper explores the connection between the timing of sapropel events in the eastern mediterranean sea and the time of low 18o events in speleothems of the soreq cave israel a new well dated 18o and 13c profile of the soreq cave speleothems for the last 140 kyr reveals five prominent low 18o events dated at 124 to 119 kyr with the main peak at 122 kyr event v 108 to 100 kyr with peaks at 107 and 102 kyr event iv 85 to 79 kyr with peak at 80 kyr event iii 55 to 52 kyr with a peak at 54 kyr event ii and 8 5 to 7 kyr with peaks at 8 5 and 7 kyr event i these events are characteristic of period of enhanced rainfall in the eastern mediterranean area particularly so for events v and i where the marked decrease in 18o and the correspondingly marked increase in 13c indicate very wet conditions the chronology of the low 18o events v iv iii and i match the ages estimated for the formation of sapropels s5 s4 s3 and s1 which are also associated with high hydrological activity thus it is suggested that the low 18o events in the soreq cave speleothems constrain the maximum duration of the sapropel formation pollen data from the sapropel layers and the isotopic pattern of the speleothems indicate that sapropels s5 and s1 were deposited during very wet periods when there were major decrease in the sea surface salinity coupled with frost free winters and drought free summers sapropels s4 and s3 were formed during periods of increased precipitation but ones in which the general climate was mediterranean semi arid

the pissouri basin fan delta complex southwestern cyprus abstract the pliocene pleistocene sedimentary fill of a small 70 km 2 sub basin in southwestern cyprus is interpreted as representing a fan delta complex with braid channels which shows a broadly progradational sequence influenced by both sea level fluctuation and tectonic activity basin differentiation began in middle late miocene with the tectonic break up of uniform carbonate deposition along southern cyprus during the latest miocene messinian salinity crisis the pissouri basin was a shallow silled depression in which thick gypsum deposits accumulated renewed basin margin faulting led to the local development of slope fan deltas followed by extensive deeper marine micrites and marlstones upwards these are intercalated with terrigenous siltstone sandstone turbidites that represent the bottomsets and foresets of a large fan delta continued uplift and erosion of troodos resulted in the southward progradation of stacked micro gilbert type deltas with interbedded terra rossa palaeosols that form the fan delta topset unit a distinctive bioclastic calcarenite sandstone body appears to represent a local channelised unit within the fan delta complex

climatic and tectonic controls on fluvial incision and aggradation in the spanish pyrenees the influences of tectonic and climatic changes on upland river systems are investigated using data from plio pleistocene terraces of the rio cinca river in the southern pyrenees this river runs transverse to the main thrust fault structures and is a major conduit for sediment delivery to the ebro basin detailed field mapping combined with long profile and palaeohydraulic reconstructions yields a comprehensive picture of changes in palaeoriver character during the plio pleistocene as the area is over 150 km from the basin outlet in the mediterranean sea changes in base level are unlikely to have influenced terrace development although tectonic activity has exerted a strong control on the position of the river the main period of thrust propagation pre dates the terraces and activity has waned from the pliocene through to the present it is concluded that the main control on incision in this area is climate through its influence on sediment supply rivers which are starved of sediment by climate change will have the power to incise whereas aggradational phases are linked to periods of increased sediment flux

landslides triggered by the 8 october 2005 kashmir earthquake abstract the 8 october 2005 kashmir earthquake triggered several thousand landslides these were mainly rock falls and debris falls although translational rock and debris slides also occurred in addition a sturzstrom debris avalanche comprising 80 million m3 buried four villages and blocked streams to create two lakes although landsliding occurred throughout the region covering an area of 7500 km2 the failures were highly concentrated associated with six geomorphic geologic anthropogenic settings including natural failures in 1 highly fractured carbonate rocks comprising the lowest beds in the hanging wall of the likely earthquake fault 2 tertiary siliciclastic rocks along antecedent drainages that traverse the hazara kashmir syntaxis 3 steep 50 slopes comprising precambrian and lower paleozoic rocks 4 very steep 50 lower slopes of fluvially undercut quaternary valley fills and 5 ridges and spur crests the sixth setting was associated with road construction extensive fissuring in many of the valley slopes together with the freshly mobilized landslide debris constitutes a potential hazard in the coming snowmelt and monsoon seasons this study supports the view that earthquake triggered landslides are highly concentrated in specific zones associated with the lithology structure geomorphology topography and human presence

evolution of quaternary alluvial fans and terraces in the intramontane pinjaur dun sub himalaya nw india interaction between tectonics and climate change quaternary alluvial fans in the tectonically active pinjaur dun an intramontane valley in the sub himalaya were deposited in front of the nalagarh thrust and were influenced both by tectonics and glacial climate fluctuations the surface morphology indicates that an earlier set of first order fans qf1 became entrenched and onlapped by a series of second order fans qf2 the younger fan segments were then cut by a pair of terraces t1 and t2 quartz optically stimulated luminescence dating establishes that the qf1 aggradational phase was initiated before 96ae 5 2 5ae3 ka and terminated after 83ae 7 1 6ae3 ka this was followed by a period of incision before qf2 fan deposition started at 72ae 4 1 3ae4 ka and continued until 24ae 5 4 ae 9k a sediment was deposited on the t1 upper and t2 lower terraces at 16ae 3 2 ae1 and 4ae5 ka respectively recording a return to overall degradation punctuated by minor deposition on terraces the period of incision separating the younger and older fan deposits coincided with enhanced sw monsoon precipitation the subsequent development of the qf2 fans and their progradation until 20 ka suggest erosional unloading of the thrust hangingwall during a tectonically quiescent phase toe cutting deposition of axial river and lacustrine facies and retreat of qf2 around 45 ka indicate fanward shift of the axial river due to tilting of the valley towards the ne in response to reactivation of the nalagarh thrust the cessation of qf2 deposition around 20 ka and the onset of through fan entrenchment suggest reduced sediment supply but relatively high stream power during the last glacial maxima lgm the prolonged stream incision since the cessation of qf2 deposition with only minor depositional phases at 16ae 3 2 ae1 and 4ae 5k a resulted from high water discharge and low sediment input during intensification of the sw monsoon and vegetation changes in the hinterland

monitoring and modelling morphological change in a braided gravel bed river using high resolution gps based survey recent research in fluvial geomorphology has emphasized the direct monitoring of channel topography as a useful tool to better understand the interrelationship between river form and process and in particular to estimate bedload transport rates and reach scale sediment budgets until recently however this morphometric approach has been limited to comparison of repeatedly surveyed cross sections with the associated problems of low frequency sampling and an emphasis on cross stream as opposed to downstream morphological dynamics recent advances in analytical photogrammetry have however permitted the acquisition of data at sufficient resolutions to represent macroform 101 m and microform 10 m channel geometry in fully three dimensions while inherently spatially distributed the photogrammetric approach to land surveying is however restricted to observable areas of the channel and is thus of limited use in the subaqueous zone especially if flows are turbid or highly coloured this paper presents an alternative approach to the study of three dimensional morphological dynamics of a divided reach of the gravelly river feshie scotland in which topographic survey of both exposed and submerged areas of the reach was undertaken using the global positioning system gps survey results from two field programmes in 1998 and 1999 are presented in which a geotronics geotracer 2000 real time kinematic gps receiving unit was used to survey a 200 80 m reach rapid radial survey methods were employed permitting the collection of 2000 survey points per day giving a mean density over the 13 ha reach of 1 1 points per square metre a detailed assessment of survey errors and dem quality is presented and a limit of detection of c 10 cm proposed as an upper threshold for the identification of significant change between dems preliminary interpretation of channel dynamics in 1998 99 reveals relatively little change to the overall macroscale reach structure dem differencing techniques however highlight important local changes including the progradation of submerged bar fronts bar head aggradation and scour along major channel thalwegs and the erosion of fines from sloughs copyright 2000 john wiley sons ltd

sea land oxygen isotopic relationships from planktonic foraminifera and speleothems in the eastern mediterranean region and their implication for paleorainfall during interglacial intervals the oxygen and carbon stable isotope compositions of cave speleothems provide a powerful method for understanding continental climate change here we examine the question of the regionality of this isotopic record and its linkage with the marine isotopic record in the eastern mediterranean em region the study presents a new accurately dated 250 kyr 18o and 13c record determined from speleothems of the peqiin cave northern israel its comparison with the continuous 185 kyr isotopic record of the soreq cave speleothems from central israel reveals striking similarities thus a strong regional climatic signal brought about by variations in temperature and rainfall amount is reflected in both cave records low 18o minima in the peqiin profile for the last 250 to 185 kyr period interglacial marine isotopic stage 7 match the timing of sapropels 9 to 7 and are indicative of high rainfall in the em region at these times the combined soreq and peqiin 18o record for the last 250 kyr excellently matches the published globigerinoides ruber g ruber marine 18o record for the em sea with the isotopic compositional difference g ruber speleothems remaining relatively constant at 5 6 0 7 thus establishing for the first time a robust exploitable link between the land and the marine isotopic records the correspondence of low 18o speleothem values and high cave water stands with low g ruber 18o values during interglacial sapropel events indicates that these periods were characterized by enhanced rainfall in the em land and sea regions by use of sea surface temperatures derived from alkenone data as a proxy for land temperatures at the soreq cave we calculate the paleorainfall 18o values and its amounts maximum rainfall and lowest temperature conditions occurred at the beginning of the sapropel events and were followed by decrease in rainfall and increase in temperatures leading to arid conditions the record for the last 7000 yr shows a trend toward increasing aridity and agrees well with climatic and archeological data from north africa and the middle east

natural oscillations in coupled geomorphic systems an alternative origin for cyclic sedimentation internally oscillating cycles of cutting and filling occur naturally in many coupled geomorphic systems as a demonstration we have modeled stream entrenchment and backfilling where alluvial systems couple to uplifting mountain blocks this simple model tracksbedrockstreamerosionandtransportofalluviumtobaselevel internaloscillations arise from coupling of a kinematic wave model for mountain erosion to a diffusion model for the alluvial basin decaying periodic cutting andfilling occur on time scales of 10 5 yr the largest magnitudes are found at the coupling point model results suggest that cyclic sedimentation may result from the tintinnabulation of single perturbations applied to natural systems and need not record cyclic changes in climate tectonics or base level

tectonic controls on drainage evolution and development of terminal alluvial fans southern pyrenees spain an understanding of how drainage patterns respond to tectonics can provide an insight into past deformational events within mountain belts and where sediment flux is supplied to depositional basins the transverse rivers draining the spanish pyrenees show sudden diversions to axial courses and the capture of lateral systems producing large trunk rivers that break through the thrust front at structurally controlled points the drainage reorganization from the initial regularly spaced pattern in the late eocene caused by the growth of thrust controlled topography influenced the location of outlets into the ebro basin the headward capture and merger of rivers as a result of structural diversion formed two large terminal fan systems during the oligo miocene along the pyrenean thrust front the early structural topographic controls on drainage evolution will have long term effects on sedimentation and stratigraphic architecture of foreland basins this will only be maintained as long as there is tectonic uplift and the river systems strive to re attain a regular drainage spacing across the orogenic belt as partly achieved in the pyrenees

tectonic and climatic controls on fan systems the kohrud mountain belt central iran abstract late pleistocene to holocene fans of the kohrud mountain belt central iran illustrate the problems of differentiating tectonic and climatic drivers for the sedimentary signatures of alluvial fan successions it is widely recognised that tectonic processes create the topography that causes fan development the existence and position of fans along the kohrud mountain belt ne of esfahan are controlled by faulting along the qom zefreh fault system and associated fault zones these faults display moderate amounts of historical and instrumental seismicity and so may be considered to be tectonically active however fluvial systems on the fans are currently incising in response to low gavkhoni playa lake levels since the mid holocene producing incised gullies on the fans up to 30 m deep these gullies expose an interdigitation of lake deposits dominated by fine grained silts and clays with evaporites and coarse gravels that characterise the alluvial fan sediments the boundaries of each facies are mostly sharp with fan sediments superimposed on lake sediments with little to no evidence of reworking in turn anhydrite glauberite mirabilite and halite crusts drape over the gravels recording a rapid return to still water shallow ephemeral saline lake sedimentation neither transition can be explained by adjustment of the hinterland drainage system after tectonic uplift the potential influence in central iran of enhanced monsoons the northward drift of the intertopical convergence zone itcz and mediterranean climates for the early holocene 6 10 ka point to episodic rainfall during winter months associated with discrete high magnitude floods on the fan surfaces the fan sediments were deposited under the general influence of a highstand playa lake whose level was fluctuating in response to climate this study demonstrates that although tectonism can induce fan development it is the sensitive balance between aridity and humidity resulting from changes in the climate regime of central iran that influences the nature of fan sequences and how they interrelate to associated facies

glacial interglacial climate changes recorded by debris flow fan deposits owens valley california abstract it is hotly debated whether and how climate changes are recorded by terrestrial stratigraphy basin sediments produced by catchment alluvial fan systems may record past climate over a variety of timescales and could offer unique information about how climate controls sedimentation unfortunately there are fundamental uncertainties about how climatic variables such as rainfall and temperature translate into sedimentological signals here we examine 35 debris flow fan surfaces in owens valley california that record deposition throughout the past 125 000 years during which climate has varied significantly we show that the last full glacial interglacial cycle is recorded with high fidelity by the grain size distributions of the debris flow deposits these flows transported finer sediment during the cooler glacial climate and became systematically coarser grained as the climate warmed and dried we explore the physical mechanisms that might explain this signal and rule out changes in sediment supply through time instead we propose that grain size records past changes in storm intensity which is responsible for debris flow initiation in this area and is decoupled from average rainfall rates this is supported by an exponential clausius clapeyron style scaling between grain size and temperature and also reconciles with climate dynamics and the initiation of debris flows the fact that these alluvial fans exhibit a strong sustained sensitivity to orbital climate changes sheds new light on how eroding landscapes and their sedimentary products respond to climatic forcing finally our findings highlight the importance of threshold controlled events such as storms and debris flows in driving erosion and sedimentation at the earth s surface in response to climate change

the role of base level change in the dissection of alluvial fans case studies from southeast spain and nevada abstract tectonics climate and base level are the underlying controls of alluvial fan development on many fans base level is stable but where base level change occurs it may itself be a response to tectonics or climatic change tectonically induced base level change will be temporally independent of climatic change and will show spatial variability depending on the rate of propagation of tectonically induced regional dissection this is illustrated by the tabernas fans southeast spain the timing of climatically induced base level change follows the timing of climatic change itself and will show more consistency of spatial relationships within groups of fans affected alluvial fans which toe out in coastal zones or at lake shorelines may be influenced by climatically controlled base level changes conventionally a fall in base level would be expected to cause dissection of the distal fan zone however the reverse may occur with fan progradation taking place in response to a base level fall and dissection occurring in response to a base level rise two contrasted case studies are considered based in part on previously published work from dry region alluvial fan zones the coastal cabo de gata fans in southeast spain and the stillwater and cold springs fans in nevada usa in these areas base level changes occurred in response to late quaternary eustatic changes of sea level and changes in the levels of pluvial lakes respectively within both areas there are fans not affected by base level change cabo de gata west coast and inland fans cold springs fans and others where base level change has been important in fan evolution cabo de gata east coast fans stillwater fans the differences in geomorphic regime between those fans influenced by base level changes and those not are expressed in morphometric contrasts and different fan profile and plan characteristics within those fans influenced by base level changes the different mechanisms have influenced the location and elevation of the zone of incision the differences can be attributed in part to the temporal interactions of base level change with climatically induced changes in sediment supply and in part to differences in gradients of the foreshore exposed by the falling sea or lake base levels

quantitative mapping of alluvial fan evolution using ground based reflectance spectroscopy abstract the ability of field based reflectance spectroscopy to resolve the relative proportions of fe oxides and clays in soils was used to map the composition relative age and distribution of segments within late quaternary fan systems in sfakia southwest crete the spectrometric results demonstrate that luvisols that have formed on the surfaces of fan segments are characterized by distinctive fe oxides types and clay minerals species furthermore fe oxide and clay concentrations display a clear and consistent trend whereby for each study fan luvisols formed on increasingly proximal fan segments are characterized by a progressive build up of spectrally distinct secondary iron oxides and clay minerals which suggests that proximal segments formed first the relative ages and hence order of formation of segments suggested by the spectral data are strongly supported by an optically stimulated luminescence osl based geochronology which provides a tentative maximum age of 144 ka for the oldest stage 1 surface and 11 2 ka for the youngest stage 2c surface moreover the chronometric data indicate that time intervals of the order 20 to 25 000 years are necessary to generate sufficient differences in pedogenic fe oxides and clay concentrations to enable differentiation of fan segments by field spectroscopy

pliocene pleistocene sedimentary and geomorphologic development of the vasilikos river catchment s cyprus in relation to uplift of the troodos ophiolite and climate related changes the pleistocene development of the vasilikos river exemplifies the interaction of focused tectonically induced surface uplift and climate influenced changes the resulting sediments are well exposed in vasilikos quarry and in the main river catchment further east an important erosional surface incises the highest level oldest fluvial conglomerates down into late pliocene early pleistocene open marine mudrocks nicosia formation allowing integration with the circum cyprus sedimentary geomorphic development f1 f4 stages to determine where the quarry deposits lie in relation to the vasilikos river catchment the fluvial deposits were mapped and valley profiles were constructed revealing four main episodes each associated with incision and distinctive fluvial deposition source lithology strongly influenced channel morphology infill and adjacent slope sediment colluvium composition palaeosols particularly red brown terra rossa developed on abandoned fluvial terraces and adjacent hillslopes especially overlying f3 surfaces the combined evidence allows close correlation of the vasilikos river and quarry deposits relatively coarse chalky conglomerate breccia and fine grained colluvium calcareous silt cyprus harvara developed especially on lower hillslopes following incision mainly above f2 and f3 surfaces based on regional comparisons overall sediment aggregation ended during the early pleistocene the f1 f2 surfaces and deposits are inferred to be middle pleistocene the f3 ones later middle pleistocene and the f4 ones near the middle late pleistocene boundary geomorphology and deposition were tectonically forced during strong focused early middle pleistocene surface uplift coarse clastic ruff off and palaeosol development terra rossa and related sediment aggradation are inferred to have increased during warm humid periods late pleistocene geomorphology and deposition were more influenced by climatic change with semi perennial streamflow rapid sediment aggradation and palaeosol terra rossa development during warm humid periods interglacials cooler glacial periods enhanced fluvial incision sediment bypassing and hillslope colluvial processes e g frost shattering downslope creep and mass flow when sediment transport bypassing exceeded sediment supply neotectonic faulting affected the catchment but did not greatly affect geomorphology or sediment supply although climate climate change and eustatic sea level change had an important influence tectonics is interpreted as the fundamental driver of geomorphological development and fluvial sedimentation with implications for other areas regionally to globally

high resolution record of northern hemisphere climate extending into the last interglacial period high resolution record of northern hemisphere climate extending into the last interglacial period

late quaternary alluvial fan terraces langshan inner mongolia china abstract alluvial fan terraces of the langshan range in the northwestern hetao basin of northern china records uplift on range bounding faults and late quaternary climate change alluvial fan profiles are segmented in the central part of the range front which lack strath terraces that developed in the southwest sw and northeast ne parts the stream channels in the central part have higher channel gradients and lower ratios of the valley floor width to valley height v four episodes of alluvial fan terraces were upstream from the range bounding fault which formation ages were estimated as 116 64 35 and 10 ka bp according to optically stimulated luminescence osl dating combined with previous 14 c and osl ages the correlation between time of the terraces formation and climatic fluctuations recorded in a guliya ice core reveals that alluvial fan aggradation was concentrated during the cold stages and that incision occurred during the succeeding cold to warm transitions a majority of alluvial fan terraces developed in accelerated uplift since 64 ka which indicates that tectonic uplift provided the driving force for continuous downcutting after climatic change triggered it geomorphic indices channel gradient and v distribution reconstructs the model of discrepant uplift in the langshan range with the fastest uplift rate in the central part which is controlled by range bounding faults

development and response of a coupled catchment fan system under changing tectonic and climatic forcing sediment fans are a potentially useful and underexploited recorder of earth s climatic and tectonic history but historical observations have led to conflicting views on the importance of tectonic climatic and lithologic variables in controlling fan morphology and deposition a one dimensional model of a sediment fan and its associated catchment is used to explore the sensitivity of such simple sediment routing systems to perturbations in fault slip and precipitation rates a transport limited catchment is coupled to a fan whose surface slope is set by the balance between catchment sediment efflux and the available tectonically generated basin accommodation rock uplift rate is spatially variable across the model space increasing the fault slip rate or decreasing the precipitation rate leads to an increase in fan slope temporary back stepping of the fan toe and a pronounced angular unconformity conversely a decrease in slip rate or an increase in precipitation rate results in a decrease in fan slope and progradation and eventual stabilization of the fan toe once perturbed the system evolves toward a new equilibrium state with time constants of 0 5 to 2 myr these response times are insensitive to slip rate but are strongly dependent on precipitation rate variations in fan slope are well described by a dimensionless parameter that expresses equilibrium slope as a function of slip rate precipitation rate system size and catchment lithology this parameter holds promise as a predictive tool in inverting the morphology of natural fans for environmental variables

facies and depositional model of alluvial fan dominated by episodic flood events in arid conditions an example from the quaternary poplar fan north western china

coastal laterite profiles at po chue tam lantau island hong kong the origin and implication abstract seven lithostratigraphic units were identified from a 180 m long up to 6 m high coastal cliff exposure at po chue tam lantau island hong kong they include older slope wash debris flow deposits raised beach deposits slope debris stream flood gravels hyperconcentrated flood gravels and younger slope wash laterite profiles had developed in the older slope wash and the debris flow deposits the profile in the former includes from bottom to top slightly weathered but ferruginized bedrock a mottled pebble cobble zone and a vesicular laterite horizon in contrast the profile in the latter consists of only debris flow deposits that contain detrital laterite fragments and underlying slightly weathered bedrock the deposits have been cemented and indurated there are no genetic links between the main zones in the laterite profiles this is evidenced by the sharp bed contact the absence of a leaching zone in the bedrock and the general constraint of the main zones by stratigraphic sequences the present study highlights that both relative accumulation of iron from pedogenic weathering and absolute accumulation of iron from a lateral source through groundwater and or surface water occur concomitantly and superimpose upon each other this leads to the development of a polygenetic laterite profile rather than a single monogenetic profile caution should be exercised to ascertain the origin of laterite before attempting to explore the paleoclimatic imprints or reconstruct landscape evolution laterites of both pedogenic and groundwater origins can represent paleosurfaces that required prolonged subaerial exposure quiescent tectonism and climatic stability

tectonic controls on the morphometry of alluvial fans around danehkhoshk anticline zagros iran article i nfo alluvial fans are important landforms where their morphology and morphometry reflect changes in tectonic climate base level and drainage basin characteristics along the margins of tectonically active mountain ranges like the zagros mountains alluvial fans are generally assumed to act as useful landforms for identify ing the level of tectonic activity the purpose of this paper is to evaluate the relationship between active tec tonics and morphometric characteristics of alluvial fans around danehkhoshk anticline in the simply folded belt of zagros morphometric characteristics of alluvial fans such as area fa slope sf length of base bf width length ratio w l radius r sweep angle sa and entrenchment e as well as valley floor width to height ratio vf and strata dips of anticline limbs dal were measured the study area was sub divided into eight tectonic zones and then the mean values of the above mentioned parameters were calculated in each zone result reveals that values of sa bf and e are directly proportional to dal the poor relationships between catchment characteristics slope and area and fan parameters are probably due to extensive karstic landforms of catchments having complex hydrologic systems and hence result in complex catchment fan relations the highly entrenched fans with high sweep angles and long bases are characteristic of tectonically active fronts of danehkhoshk anticline having v shaped valleys higher vf values steep triangular facets and more rotated limbs higher dal values apart from the tectonic control on fan development the fan head entrenchment and negative accumulation spaces on most alluvial fans can be attributed to decreased sediment load and discharge the drier the present day climate regime

review and new aspects concerning the formation of eastern mediterranean sapropels abstract in this paper it is proposed that the formation of eastern mediterranean sapropels occurred in an anti estuarine type of circulation which was to some degree weakened relative to the present in response to reduction of the eastern mediterranean excess of evaporation over freshwater input this reduction of excess evaporation would have been imposed by intensifications of 1 the indian ocean summer sw monsoon influencing the eastern mediterranean via increased nile discharge and 2 the system of mediterranean depressions an element of the westerly atlantic system causing increased precipitation and decreased evaporation both the indian ocean summer monsoon and the westerly atlantic system would be intensified in response to the occurrence of distinct minima in the cycle of precession it is demonstrated that reduced excess evaporation whether or not coinciding with global phases of deglaciation would lead to reduction of surface water salinities in the eastern mediterranean causing isolation of previously formed high salinity cooler deep water thus mixing was severely reduced possibly even restricted to eddy diffusion with only occasional convective events that because of the existing density gradient hardly ever would reach the deepest parts of the basin the consequently diminished oxygen advection down from a few hundred meters in the water column favoured preservation of the sinking organic matter this would however suffice only to enable the formation of sapropels with low organic carbon contents the high organic carbon contents observed in various sapropels are argued to reflect superimposed increases of export production the described scenario accounts for previously reported 1 increases of organic carbon content with increasing depth of deposition within individual sapropels and 2 asymmetrical sequences of sapropel deposition characterized by gradual build up and rather abrupt ending it is furthermore in agreement with 3 isotopic and faunal reconstructions of the history of exchange transports through both the strait of sicily and the strait of gibraltar and 4 faunal and floral reflections of the presence or absence of a distinct deep chlorophyll maximum with its associated increases in export production indicating the presence or absence of a shallow pycnocline within the euphotic layer moreover the described scenario 5 is in no way conflicting with the reports of sapropels in the western mediterranean and 6 seems to be endorsed by occasionally intercalated intervals suggestive of somewhat improved oxygenation amidst anoxic benthic desert levels a situation that has been observed in a few quaternary and pliocene sapropels

cement fabrics and optical luminescence ages of beachrock north cyprus implications for holocene sea level changes abstract caco 3 cemented beachrocks are widely found along the northern coast of cyprus in this study we aim to discuss the cementation history of beachrocks at ten particular sites within the context of holocene sea level changes cement fabrics petrographic and geochemical characteristics and optically stimulated luminescence ages of buried quartz grains were studied the seaward inclined 5 10 parallel stratified beds are composed mostly of sandstone alternating with conglomerate ooids benthic and planktic foraminifera bioclasts of red algae echinoid spines and gastropods make up a significant proportion of the cemented beds with caco 3 content ranging between 37 and 65 poorly sorted grains are bonded by four distinct cements circumgranular micritic coatings sparry calcite infillings pore fills and meniscus bridges this consecutive nature of cementation is typical of a marine phreatic and meteoric vadose environment when the sea level was lower than present but had a tendency to increase during middle to late holocene osl ages ranging from 5 4 ka to 0 38 ka indicate that the deposition and ensuing cementation of the quartz grains occurred during two main stages younger beds dated between 2 3 ka and 0 38 ka and older beds from 2 3 ka to 5 4 ka a period devoid of beachrock formation was attested between 3 5 ka and 2 3 ka

braided stream and flood plain architecture the rio vero formation spanish pyrenees early to middle miocene fluvial sandstones of the rio vero formation were studied in an area around the town of barbastro south central pyrenees spain the outstanding quality of outcrops in this area allows a three dimensional study of architectural elements six architectural elements are recognised described in detail and interpreted from three key localities seven main lithofacies were identified and sub divided into gravelly sandy and fine grained lithofacies the architectural elements and lithofacies have been combined with a hierarchy of depositional bounding surfaces to fully interpret the evolution of the depositional system at the meso and macro scale not only the different architectural elements and lithofacies of the complete braided fluvial system but also the lateral variation of the architectural elements were emphasised in this study differential tectonic movements seasonal climate change and their effect on vertical and lateral evolution of the area were the main control on basin sedimentation channel interconnection palaeocurrent patterns and consequently the fluvial architecture the presence of lateral ramp anticlines caused the fluvial system to be laterally restricted with the main channel belts being located in the areas of highest subsidence and lowest topography intervening topographic highs acted as both flood plains and lateral barriers between the main channel systems the proposed depositional model comprises broad low sinuosity perennial but seasonal moderate energy streams the sandstone architecture is dominated by channel fill and sheet sands and associated simple and more complex bars adjacent to the main channel belts fine grained sandstones siltstones and immature paleosols occur the along strike relationship between major fluvial systems and their outlets into a foreland basin has important implications for the infill of the basin and the modelling of fluvial systems along mountain belt fronts

climate of the last 53 000 years in the eastern mediterranean based on soil sequence stratigraphy in the coastal plain of israel abstract in this paper we present a detailed record of proxy climatic events in the coastal belt of the eastern mediterranean during the past 53 000 years a sequence of alternating palaeosols aeolianites and dune sands which have been dated by luminescence and by 14c was studied by the magnetic susceptibility particle size distribution clay mineralogy and soil micromorphology thirteen proxy climatic events demonstrating fluctuations of relatively dry and wet episodes were recognized the soil parent materials as well as the different soil types were rated in a semi quantitative dry to wet scale the palaeosol sequence is compared to a proxy climatic record of oxygen and carbon isotopes in speleothems from a karstic cave in central israel and to a record of lake levels of lake lisan and its successor which is known as the dead sea a genuine red mediterranean soil rhodoxeralfs localy designated as hamra soil developed during the last glacial stage from 40 to 12 5 thousand calendar years bp climatic fluctuations that were recorded in speleothems and in changing lake levels were not preserved in this soil during the cold and dry younger dryas ca 12 5 to 11 5 calendar ka bp a thick bed of loess material deriving from atmospheric dust of the sahara and arabian deserts covered the entire coastal belt during this phase lake lisan was desiccated and turned into the modern smaller dead sea during the early holocene some 10 7 5 calendar ka bp a second red hamra soil developed in warm and wet environments associated with a relatively high stand of the dead sea level a depletion of 18o and a significant enrichment of 13c in the speleothems were recorded during this episode this event was in phase with the widespread distribution of freshwater lakes in the sahara desert and the accumulation of the s1 sapropel in the eastern mediterranean several small scale dry and somewhat wet fluctuations of the late holocene from 7 5 calendar ka bp to the present were recorded in the coastal belt changes in human history as reflected in archaeological records are associated with proxy climatic fluctuations periods of desertification and deterioration are coupled with dry episodes periods of relative human prosperity are coupled with wetter episodes

structures and textures in triassic braided stream conglomerates bunter pebble beds in the sherwood sandstone group north staffordshire england in the northern parts of the needwood and stafford eccleshall basins england the pebble beds of the sherwood sandstone group contain thick successions of texturally mature fluvial pebble cobble conglomerates which are organized into either horizontal or cross stratified sets the horizontally lying sets generally coarser grained and more poorly sorted than the cross bedded sets are usually disorganized and either matrix or clast supported although thin lenses of well sorted occasionally openwork units interpreted as falling stage phenomena are often present the cross stratified conglomerates have foresets exhibiting remarkable textural organization with a coarse bimodal sometimes matrix supported part grading upwards or being abruptly overlain by a finer well sorted occasionally openwork part and finally capped by sandstone these rhythmic textural changes are attributed partly to an avalanche process at high stage and partly to falling stage conditions the most common types of vertical association are thick successions of horizontally bedded conglomerates up to 20 m and sequences of an upwards coarsening nature 2 12 m in which cross stratified sets are overlain by flat lying sets the environment of deposition of the gravels is interpreted as one in which water depths at high stage were greater than depths in most modern braided stream plains proglacial or alluvial fan but shallower than depths associated with the pleistocene catastrophic floods from which texturally mature giant gravel bars have been recorded recent braided streams with relatively confined channels and considerable bar channel relief are better analogues in particular medial or mid channel bars with a two tier structure subaqueous and partly emergent portions may explain the upward coarsening sequences in which horizontally lying conglomerates overlie cross stratified conglomerates the thicker sequences of horizontally stratified conglomerates represent proximal longitudinal bar deposits sheets of pebbly sandstone and argillaceous sandstone lying between the conglomerates and commonly occurring towards the top of the succession largely represent deposition from sandwaves and dunes finer interbedded argillaceous sandstones siltstones and mudstones are interpreted as overbank and waning flood deposits basin forming tectonism of increasing intensity probably caused the initial coarsening upwards of the lower part of the succession whilst more stable tectonic conditions and decreasing relief on the margins of the basins and in the areas of provenance in the midlands and the hercynides account for the upwards fining of the upper part of the succession

quaternary uplift and sea level change at an active plate boundary cyprus a combination of northward underthrusting of the african plate and serpentinite diapirism resulted in progressive uplift of cyprus during the quaternary the uplift was associated with the development of succession of alluvial fans and marine terraces marine terraces in coastal southern cyprus are developed at 350 360 m 110 100 m 60 50 m 11 8 m and 2 3 m above present sea level the terraces display sequences of regressive deltaic carbonate and siliciclastic sub littoral to littoral and sub aerial type alluvial fans of the fanglomerate group crop out on the northern flanks of the troodos massif forming extensive dissected peneplaned terraces later uplift resulted in the formation of channel fans and river terraces proximal sheetflood conglomerates pass distally into channelized braid plain environments on the southern margin of the troodos massif the fanglomerate group comprises braided channelized and floodplain sequences which pass laterally into littoral facies provenence studies indicate that uplift and resulting erosion of cyprus was centred on the troodos massif mount olympus radiometric dates indicate that uplift was rapid in the early and mid pleistocene in the late pleistocene holocene eustatic sea level changes and anthropogenic effects dominated while the rate of uplift was reduced with local submergence of southern coastal areas

lake levels and sequence stratigraphy of lake lisan the late pleistocene precursor of the dead sea lake lisan the late pleistocene precursor of the dead sea existed from 70 000 to 15 000 yr b p it evolved through frequent water level fluctuations which reflected the regional hydrological and climatic conditions we determined the water level of the lake for the time interval 55 000 15 000 cal yr b p by mapping offshore nearshore and fan delta sediments by application of sequence stratigraphy methods and by dating with radiocarbon and u series methods during the studied time interval the lake level fluctuated between 340 and 160 m below mean sea level msl between 55 000 and 30 000 cal yr b p the lake evolved through short term fluctuations around 280 290 m below msl punctuated at 48 000 43 000 cal yr b p by a drop event to at least 340 m below msl at 27 000 cal yr b p the lake began to rise sharply reaching its maximum elevation of about 164 m below msl between 26 000 and 23 000 cal yr b p then it began dropping and reached 300 m below msl at 15 000 cal yr b p during the holocene the lake corresponding to the present dead sea stabilized at ca 400 m below msl with minor fluctuations the hypsometric curve of the basin indicates that large changes in lake area are expected at above 403 and 385 m below msl at these elevations the lake level is buffered lake lisan was always higher than 380 m below msl indicating a significantly large water contribution to the basin the long and repetitious periods of stabilization at 280 290 m below msl during lake lisan time indicate hydrological control combined with the existence of a physical sill at this elevation crossing this sill could not have been achieved without a dramatic increase in the total water input to the lake as occurred during the fast and intense lake rise from 280 to 160 m below msl at 27 000 cal yr b p

a chronology of alluvial fan response to late quaternary sea level and climate change crete abstract to better understand how fluvial systems respond to late quaternary climatic forcing osl and u series dating was applied to stratigraphically significant sedimentary units within a small 2 alluvial fan system the sphakia fan in southwest crete the resultant chronology comprising 32 osl and u series ages makes sphakia fan one of the best dated systems in the mediterranean and suggests that cretan fans responded to climate in two ways first during the transitions between marine isotope stage mis 5a 4 and mis 2 1 sphakia fan was characterised by significant entrenchment and distal shift in the zone of deposition it is proposed that the phases of entrenchment were driven by sea level induced base level fall during mis 5a 4 and landscape stabilisation during the onset of the current interglacial mis 2 1 second with the exception of these two entrenchment episodes fan alluviation occurred across the entire last interglacial glacial cycle in all climatic settings i e interglacials interstadials and stadials it is likely that the topographic setting of the catchment supplying sediment to sphakia fan maintained high sediment transfer rates during most climatic settings enabling fan aggradation to occur except during major climatic driven transitions i e major sea level fall and postglacial vegetation development

the sedimentology and accretionary styles of an ancient gravel bed stream the budleigh salterton pebble beds lower triassic southwest england abstract three accretionary styles are present in the fluvial conglomerates and pebbly sandstones of the lower triassic budleigh salterton pebble beds bspb of east devon the lower portions of this 20 30 m sequence are dominated by extensive 50 m sheets or narrow lenses of planar cross bedded conglomerate sets 1 3 m thick these abruptly pass both downstream and laterally into horizontally bedded conglomerates cross bedded sandstones and muddy sandstones this accretionary style reflects deposition from linguoid shaped macroforms whose distal margins were bounded by slipfaces they accreted at anabranch confluences and as bank attached bars in relatively confined and channelised gravel bed streams lateral facies changes represent macroform evolution resulting from changing discharges or abandonment of a channel reach followed by accretion of a new macroform the upper portions of the bspb mainly comprise couplets of horizontally bedded conglomerate overlain by large scale trough cross bedded sandstone the conglomerate shows local channel macroform relief and lateral and downstream transitions into sets of gently dipping conglomerate this style of accretion represents deposition in less confined and less channelised fluvial systems by relatively low relief gravel macroforms and large sand dunes the third style recognised in the bspb is much more localised it consists of wedge like sets of large scale trough cross bedded conglomerate the sets are formed by erosion and subsequent fill of scours cut into a thick sandy substrate techniques of lateral profile analysis and hierarchical ordering of bounding surfaces can usefully be applied to some parts of the bspb this is important as the approach was originally developed for the deposits of sand bed streams however this approach is more difficult to apply to fluvial conglomerates because of the cryptic nature of some gravel stratification the appearance and character of some hierarchies of bounding surfaces may differ from their equivalents in fluvial sandstones

river avulsions and sedimentary evolution of the luanhe fan delta system north china since the late pleistocene abstract the luanhe fan delta lfd is one of the most important coastal deltas in north china numerous investigations on the late quaternary evolution of this fan delta system have been implemented during the 1980s however few detailed sedimentologic studies have been undertaken based on comprehensive analysis of sedimentary facies grain size microfossils radiocarbon dates ams14c and optically stimulated luminescence osl ages from three 30 m long cores along with recent reports from a series of cores and seismic profiles from the coastal areas we reconstructed the detailed late quaternary sedimentary evolution of the northern bohai coast which evolved from a coastal barrier lagoon system during mis5 to an alluvial plain with river channels and floodplains between mis4 and the early holocene a variety of transgressive coastal depositional environments freshwater marshes beach ridges sandy barriers shallow seas developed during the early holocene these environments were followed by delta progradation the delta system then gradually turned into a coastal barrier lagoon system under the combined impact of prevailing wave driven currents and local subsidence two dramatic 90 degree diversions of the lower luanhe river course likely influenced the sedimentary evolution of the lfd in its inner portion the first avulsion took place in qianxi probably at the end of the late pleistocene 15 000 cal a bp it led to the abandonment of the luanhe alluvial fan in the western part of the northern bohai coastal plain nbcp and to the formation of a new alluvial fan in the eastern nbcp this alluvial fan evolved into a fan delta system 7000 3500 cal a bp during the holocene transgression the second avulsion occurred at zhuacun during the late holocene probably at 3600 100 cal a bp following this latter avulsion the luanhe river shifted toward the east and formed a new fan delta system 3700 cal a bp present with its apex in luanzhou abrupt tectonic uplift in this highly seismic region likely controlled the two avulsions and the dramatic shift of the alluvial fan complexes climate and sea level changes may also have partly influenced the development of the lfd

sedimentology of two fan delta systems in the pliocene pleistocene of the mesaoria basin cyprus abstract two fan delta systems have been recognised in the pliocene pleistocene deposits of the mesaoria basin an asymmetrical half graben located on the northern side of the troodos ophiolite cyprus the older fan delta system the pliocene nicosia formation was deposited when the mesaoria basin was actively subsiding it comprises a number of small isolated fan deltas which built across a narrow

impact of periodicity on sediment flux in alluvial systems grain to basin scale periodicity is a common component of many sedimentological processes but seldom is it considered across all scales of fluvial processes in order to understand the complete impact on sediment supply to basins temporal changes in sediment supply within drainage systems and sedimentary basins are a consequence of the inherent instability in transport processes the causes of fluctuations are of 2 main types i changes in factors endemic to the supply of sediment but which are at least partly independent of erosive forces and ii changes in the magnitude of forces available to transport sediment fluctuations at spatial scales from grain through reach to basin scales and at temporal scales from minutes to millennia are discussed and evaluated all fluctuations are reflected in sedimentary deposits in some way for example irregular patterns of bed break up during erosion can generate bedforms that are recorded in deposits the passage of waves of sediment can cause cycles of incision and aggradation in a reach large flood events will flush sediment into coastal regions and will be recorded as an identifiable package in the deposits many models of basin processes and products assume a consistent supply of sediment which is far from the case in nature one of the challenges in the coming decade is to move away from using long term averages of sediment supply and to link models directly into geomorphic processes

a retreating fan delta system in the northwestern junggar basin northwestern china characteristics evolution and controlling factors abstract in this study we use seismic reflection logging and core data to investigate the depositional systems and their controlling factors in the lower triassic in the northwestern margin of junggar basin the succession shows strong lateral and vertical facies variation the facies associations indicate the development of conglomeratic fan delta system with characteristics of fining upward and landward migration of facies belts a critical balance between progradation aggradation and retrogradation controlled the evolution of delta successions within an overall transgressive regime migration of the locus of active faulting exerted the primary control on fan delta thickness variations on the sandy component and gravel type within the fan delta system among different units indicate the control of provenance the climate significantly influenced the mode of sediment transfer from the feeder system to the basin the significant climate change from arid to humid played a primary role in controlling the fan delta architecture our study suggests that in tectonic active basin the controls of tectonics on the sequence stratigraphy are still fundamental however during the tectonic quiescence or rift depression transition stage significant changes of climate would play a primary role in controlling the sediment dispersal the current study reveals that the hydrocarbon reservoir shows a landward migration trend within a retreating fan delta system

late quaternary alluvial fans of emli valley in the ecemis fault zone south central turkey insights from cosmogenic nuclides abstract alluvial fans within the paraglacial ecemis river drainages on the aladaglar mountains in south central turkey were studied using geomorphological sedimentological and chlorine 36 terrestrial cosmogenic nuclide tcn surface exposure dating methods to examine the timing of alluvial fan abandonment incision and to understand the role of climatic and tectonic processes in the region these alluvial fan complexes are among the best preserved succession of alluvial fans in turkey and they were offset by the major strike slip ecemis fault of the central anatolian fault zone the alluvial fans are mostly composed of well lithified limestone cobbles 5 to 25 cm in size and comprise crudely stratified thick beds with a total thickness reaching up to about 80 m tcn surface exposure dating indicates that the oldest alluvial fan surface yalak fan was likely formed and subsequently abandoned latest by 136 0 23 4 ka ago largely on the transition of the penultimate glaciation marine isotope stage 6 mis 6 to the last interglacial mis 5 i e termination ii the second set of alluvial fan emli fan was possibly developed during the last interglacial mis 5 and incised twice by between roughly 97 0 13 8 and 81 2 13 2 ka ago a younger alluvial fan deposit placed on relatively older erosional terraces of the emli fan suggests that it may have been produced during the last glacial cycle mis 2 these events are similar to findings from other fluvial and lacustrine deposits throughout central anatolia the incision times of the ecemis alluvial fan surfaces largely coincide with major climatic shifts from the cooler glacial periods to warmer interglacial interstadial conditions this indicates that alluvial fans were produced by outwash sediments of paleoglaciers during cooler conditions and later when glaciers started to retreat due to a major warming event the excess water released from the glaciers incised the pre existing fan surfaces an alluvial fan in the study area was also cut by the ecemis fault highlighting the influence of tectonics on fan development it was offset vertically 35 3 m since at least 97 0 13 8 ka which suggests a 0 36 0 06 mm a 1 vertical slip rate of the fault

the reconstruction of past climates using multi proxy evidence an example of the weichselian pleniglacial in northwest and central europe abstract different lines of terrestrial biotic and abiotic evidence are used for large scale climate reconstructions to transform proxy data into climate parameter values standardisation procedures are defined and described as each type of biotic and abiotic proxy provides its own climate parameter a detailed climate reconstruction may be obtained the multi proxy database for palaeoclimate reconstruction is a specially designed computer database that facilitates data processing and management of weichselian climate proxies this paper describes the application of multi proxy evidence to reconstruct the climate across lowland northwest and central europe during the interval 41 38 bp for this period the mean temperature of the warmest month is estimated at 10 to 11 c and the mean temperature of the coldest month ranges from 27 to 20 c the annual range suggests a cold continental setting with an estimated mean annual temperature between 9 and 4 c a north to south transition from dis continuous permafrost to seasonally frozen ground is suggested by periglacial evidence

pleistocene terrace deposition related to tectonically controlled surface uplift an example of the kyrenia range lineament in the northern part of cyprus abstract in this study we consider how surface uplift of a narrow mountain range has interacted with glacial related sea level cyclicity and climatic change to produce a series of marine and non marine terrace systems the terrace deposits of the kyrenia range record rapid surface uplift of a long lived tectonic lineament during the early pleistocene followed by continued surface uplift at a reduced rate during mid late pleistocene six terrace depositional systems are distinguished and correlated along the northern and southern flanks of the range termed k0 to k5 the oldest and highest k0 terrace system is present only within the central part of the range the k2 k5 terrace systems formed later at sequentially lower levels away from the range the earliest stage of surface uplift k0 terrace system comprises lacustrine carbonates interbedded with mass flow facies early pleistocene the subsequent terrace system k1 is made up of colluvial conglomerate and aeolian dune facies on both flanks of the range the later terrace systems k2 to k5 each begin with a basal marine deposit interpreted as a marine transgression deltaic conglomerates prograded during inferred global interglacial stages overlying aeolian dune facies represent marine regressions probably related to global glacial stages each terrace depositional system was uplifted and preserved followed by subsequent deposits at progressively lower topographic levels climatic variation during interglacial glacial cycles and autocyclic processes also exerted an influence on deposition particularly on short period fluvial and aeolian deposition

vegetation and climate in the early and pleni weichselian in northern central europe analysis of numerous pollen diagrams from north and central germany and from the adjacent lowlands of the netherlands denmark poland and belarus have facilitated a regional comparison of the vegetation and climatic evolution from the beginning of the early weichselian glaciation to the weichselian pleniglacial data from geological studies and analysis of fossil beetles and plant macroremains have been used to supplement the palaeoclimatic reconstruction up to the end of the oerel interstadial the palaeoclimate was characterised by increasing continentality the winter temperatures in particular tended to fall continuously during the stadials and the interstadials of the early weichselian and early pleniglacial in the brorup and odderade interstadials summer temperatures where sufficiently high to enable boreal forests to grow whereas in the oerel interstadial summer temperatures were such that tree growth was inhibited it is probable that falling sea level and the consequent extension northwards of the north sea coast were the main causes of increasing continentality in the latter part of the pleniglacial peat accumulation frequently took place and humic silts were deposited under lacustrine conditions correlation between various sites is extraordinarily difficult pollen diagrams from the so called interstadials of the glinde moershoofd complex hengelo and denekamp are similar to those of the known early weichselian stadials it is proposed therefore that these interstadials should be called intervals and that the term interstadial be reserved for climatic variations that result in distinctive pollen assemblages and which in turn reflect distinctive vegetation dynamics interstadials should be capable of being characterised on a biostratigraphical basis and it should be possible to establish correlations over considerable distances according to this definition the first three warm oscillations of the weichselian glaciation in the central european lowlands are the brorup odderade and oerel interstadials all other pleniglacial peat layers should be assigned the rank of interval copyright 2001 john wiley sons ltd

timing of uplift of the troodos massif cyprus constrained by sedimentary and magnetic polarity evidence abstract plio pleistocene sediments exposed around the ophiolitic troodos massif document spectacular uplift from below sea level to a maximum height of c 2000 m sedimentation reflects a dominant control of focused tectonic uplift modified by the effects of glacio eustatic sea level change and climatic change understanding the uplift and controls on deposition has been hindered by an inadequate age model here we present a preliminary investigation of the polarity of remanent magnetizations recorded within the upper part of the pliocene succession in the pissouri and mesaoria basins and from the pleistocene marine terrace deposits that border the troodos massif when integrated with available lithostatigraphic and biostratigraphic data the main results are as follows focused uplift of the troodos massif began during the late pliocene either between 2 14 and 1 95 ma or immediately prior to 1 77 ma shallow marine ophiolite derived clastic and bioclastic sediments accumulated in both the mesaoria and pissouri basins implying that the troodos massif was uplifted as a single tectonic entity non marine deltaic and fluvial facies prograded into both of the basins during the pleistocene 1 77 ma recent marine terraces in sw and south cyprus were cut and covered by littoral sediments from

earthquake triggered increase in sediment delivery from an active mountain belt in tectonically active mountain belts earthquake triggered landslides deliver large amounts of sediment to rivers we quantify the geomorphic impact of the 1999 mw 7 6 chi chi earthquake in taiwan which triggered 20 000 landslides coseismic weakening of substrate material caused increased landsliding during subsequent typhoons most coseismic landslides remained confined to hillslopes downslope transport of sediment into the channel network occurred during later storms the sequential processes have led to a factor of four increase in unit sediment concentration in rivers draining the epicentral area and increased the magnitude and frequency of hyperpycnal sediment delivery to the ocean four years after the earthquake rates of hillslope mass wasting remain elevated in the epicentral area

distinctive characteristics of a streamflow dominated alluvial fan deposit sanghori area kyongsang basin early cretaceous southeastern korea abstract in the northwestern part of the non marine kyongsang basin early cretaceous conglomeratic deposits occur at intervals along the northern basin margin and grade basinward into interbedded sandstone and mudstone one of these conglomeratic deposits referred to as the sanghori deposit is 150 m thick and characterized by amalgamated sheets of conglomerate and sandstone facies assemblages 1 and 2 alternating with interbedded sandstone and purple siltstone facies assemblage 3 facies assemblage 1 comprises clast supported disorganized and organized sheet conglomerates interbedded with massive to stratified sandstones this assemblage is interpreted as the product of proximal gravel bed stream deposition facies assemblage 2 consists of trough and planar cross stratified and horizontally stratified sandstones it represents sandy braided stream deposits in which sand bars and dunes were common sedimentary facies and architecture of the coarse grained facies assemblages suggest that the gravel bed and sandy braided streams were wide and shallow and rapidly aggraded during flash floods facies assemblage 3 consists of interbedded purple siltstone and tabular sandstone which show evidence of weak pedogenic modification and bioturbation these characteristics are interpreted as the result of floodplain processes sediments were supplied from the north and dispersed radially forming a streamflow dominated alluvial fan system the sanghori alluvial system was most probably fed from a large drainage basin resulting in the predominance of streamflow deposits and rounded clasts the alternation of the gravel bed stream and floodplain deposits was due to autocyclic switching of active fan sectors under the conditions of relatively slow and steady basin subsidence

the occurrence of bassanite in some australian arid zone soils abstract bassanite was found to be stable in restricted soil profiles of the australian arid zone the mineral was converted to gypsum when allowed to soak in water the field occurrence of the mineral seems to suggest that the present arid climate rather than past humid conditions has favoured the formation of bassanite

tertiary palaeosurfaces of the sw deccan western india implications for passive margin uplift two genetically distinct lateritized palaeosurfaces of different ages are recognized in the southwest deccan traps region of western india using a combination of geochemical topographical and satellite image data the deccan traps were erupted at the cretaceous tertiary boundary c 65 ma and comprise a huge area of originally near horizontal basalt lavas covering much of northwest peninsular india and topographically forming the coast parallel western ghats escarpment and elevated maharashtra plateau to the east remnants of the older palaeosurface currently exist as a series of isolated laterite capped plateaux forming the highest elevations along the western ghats 15 30 18 15 n this surface is of late cretaceous early tertiary age and originally developed upon flows which lay at or near to the top of the lava sequence this lateritization phase was terminated by a period of uplift and extensive erosion in lower to mid tertiary times during which the low lying low relief coastal konkan plain developed through the eastward recession of the ghats scarpline a second phase of lateritisation occurred upon this coastal pediplain during mid to late tertiary times since the earlier uplift had gently deformed the lava pile prior to the development of the pedimented surface the low level konkian laterite lies with marked angular unconformity upon the lava stratigraphy both surfaces have been subject to further large scale distortion resulting from continuing uplift effects development and evolution of these deccan palaeosurfaces is important since together they provide a record of uplift effects in western india moreover they offer a datum against which the uplift erosional history may be further constrained and demonstrate that uplift effects have acted upon the indian margin throughout the tertiary since such longevity of uplift is difficult to reconcile with the commonly cited thermal and dynamic post rift mechanisms known to act upon passive margins the morphological and structural evolution of the rifted deccan margin is better described in terms of denudational isostasy

earthquake generation in cyprus revealed by the evolving stress field abstract strong earthquake occurrence m 6 0 onshore and offshore the cyprus island constitutes significant seismic hazard because they occur close to populated areas seismicity is weak south of the island along the cyprean arc and strong events are aligned along the paphos transform fault and larnaka thrust fault zone that were already known and the lemessos thrust fault zone that defined in the present study by combining the past history of strong m 6 0 events and the long term tectonic loading on these major fault zones the evolution of the stress field from 1896 until the present is derived although uncertainties exist in the location magnitude and fault geometries of the early earthquakes included in our stress evolutionary model the resulting stress field provides an explanation of later earthquake triggering it was evidenced that the locations of all the strong events were preceded by a static stress change that encouraged failure the current state of the evolved stress field may provide evidence for the future seismic hazard areas of positive static stress changes were identified in the southwestern offshore area that can be considered as possible sites of future seismic activity

palaeosols and late pleistocene rainfall fluctuations in the negev desert the existence of a series of palaeosols in the present day desert region of southern israel the northern negev desert 1 2 indicates recurring periods of wetter climate in the past up to seven well developed palaeosols occur within a section and each has a horizon containing soft calcium carbonate nodules 3 15 mm in diameter the palaeosols are developed within loess or fluvially redeposited loess consisting of silty clay or clayey silt the 14c ages of the uppermost three calcic horizons average 13 000 yr bp calcic horizon ch i 28 000 yr bp ch ii and 37 000 yr bp ch iii drier phases occurred between these periods of pedogenesis especially during the last glacial maximum centred at 18 000 yr bp when extensive erosion occurred analysis of the 13c content of nodule carbonates points to the occurrence of strong north south rainfall gradients during each period of calcic horizon formation which excludes the possibility of monsoonal rains contributing to the increased rainfall during these periods the palaeosols correspond to global warm phases of the last glacial period

approaches to middle stone age landscape archaeology in tropical africa the southern montane forest grassland mosaic ecosystem in the humid subtropics southern rift valley of africa comprised the environmental context for a large area in which modern human evolution and dispersal occurred variable climatic conditions during the late pleistocene have ranged between humid and hyperarid changing the character of the ecosystem and transforming it at different points in time into a barrier a refuge and a corridor between southern and eastern african populations alluvial fans presently blanket the areas adjacent to major river systems which were key areas of prehistoric human habitation these sets of variables have created conditions that are both challenging and advantageous to conduct archaeological research lateritic soil development has resulted in poor organic preservation and facilitated insect bioturbation which has demanded an integrated micro macro scale approach to building a reliable geochronology an integrated field and analytical methodology has also been employed to identify the nature and degree of post depositional movement in alluvial deposits which preserve a wide range of spatial integrity levels in buried stone artifact assemblages between 47 and 30 ka in karonga northern malawi this paper describes the methodological advances taken toward understanding open air middle stone age archaeology in sub tropical africa and explores the inferential potential for understanding pleistocene human ecology in the important southern rift valley region

stream dominated alluvial fan and lacustrine depositional systems in cenozoic strike slip basins denali fault system yukon territory canada ancient stream dominated wet alluvial fan deposits have received far less attention in the literature than their arid semi arid counterparts the cenozoic basin fills along the denali fault system of the northwestern canadian cordillera provide excellent examples of stream dominated alluvial fan deposits because they developed during the eocene oligocene temperate climatic regime in an active strike slip orogen the amphitheatre formation filled several strike slip basins in yukon territory and consists of up to 1200 m of coarse siliciclastic rocks and coal detailed facies analysis conglomerate sandstone percentages c s maximum particle size mps distribution and palaeocurrent analysis of the amphitheatre formation in two of these strike slip basins document the transition from proximal to middle to distal and fringing environments within ancient stream dominated alluvial fan systems proximal fan deposits in the bates lake basin are characterized by disorganized clast supported boulder conglomerate and minor matrix mud supported conglomerate proximal facies are located along the faulted basin margins in areas where c s 80 to 100 and where the average mps ranges from 30 to 60 cm proximal fan deposits grade into middle fan channelized well organized cobble conglomerates that form upward fining sequences with an average thickness of 7 m middle fan deposits grade basinward into well sorted laterally continuous beds of normally graded sandstone interbedded with trough cross stratified sandstone these distal fan deposits are characteristic of areas where c s 20 to 40 and where the average mps ranges from 5 to 15 cm fan fringe deposits consist of lacustrine and axial fluvial facies palaeogeographic reconstruction of the bates lake basin indicates that alluvial fan sedimentation was concentrated in three parts of the basin the largest alluvial fan system abutted the strike slip duke river fault and prograded westward across the axis of the basin two smaller coarser grained fans prograded syntaxially northward from the normal faulted southern basin margin facies analysis of the burwash basin indicates a similar transition from proximal to distal stream dominated alluvial fan environments but with several key differences middle fan deposits in the burwash basin define upward coarsening sequences 50 to 60 m thick composed of fine grained lithofacies and coal in the lower part trough cross stratified sandstone in the middle and conglomerate in the upper part of the sequence upward coarsening sequences 90 140 m thick also are common in the fan fringe lacustrine deposits these sequences coarsen upward from mudstone through fine grained ripple laminated sandstone to coarse grained trough cross stratified sandstone the upward coarsening sequences are basinwide facies independent and probably represent progradation of stream dominated alluvial fan depositional systems coal distribution in the amphitheatre formation is closely coupled with predominant depositional processes on stream dominated alluvial fans the thickest coal seams occur in the most proximal part of the basin fill and in marginal lacustrine deposits coal development in the intervening middle and distal fan areas was suppressed by the high frequency of unconfined flow events and lateral channel mobility

timescales climate and river development abstract in the long term glacial interglacial sequences river development follows general climatic evolution however at the scale of one cold warm cycle it appears that the geomorphological effect of river activity is best expressed at times of climatic change such periods of pronounced fluvial action last only a short time in more detail the internal evolution in a drainage basin after a climatic event results in a delayed response of the morphology and sedimentation pattern finally on the shortest timescale local thresholds may play a decisive role in the reactions of river systems it is concluded that the relation between fluvial development and climate is not a simple one but is fundamentally dependant on the timescale

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

pleistocene geomorphological and sedimentary development of the akaki river catchment northeastern troodos massif in relation to tectonic uplift versus climatic change the uplift of the troodos ophiolite is reflected in the development of the akaki river catchment in the northeast troodos massif four main stages f1 f4 of geomorphological terrace development and related deposits are recognised using satellite imagery and field observations the geomorphological terraces have been tectonically uplifted during the pleistocene so that they dip northwards from the troodos mountains until they merge with the mesaoria plain lithology e g hard diabase versus soft extrusive rock has exerted an important control on the geomorphology of the akaki river channel the f1 terraces and related deposits are well preserved in the lower reaches of the catchment the f2 terraces are more widely preserved but with few preserved deposits the f3 erosional surfaces e g strath terraces and related deposits are widespread up into the higher reaches of the catchment the f4 to recent geomorphological surfaces and deposits are confined to near the modern river channel the f1 to f3 aged deposits each include very high energy mass flow deposits and somewhat lower energy traction flow deposits with minimal sand preservation stages of fluvial aggradation were followed by soil development e g terra rossa the f1 to f4 aged terraces and related deposits mainly formed in response to a combination of very long term tectonic uplift and climatic related change long term and short term tectonic uplift was the dominant driver related to the updoming of the troodos ophiolite especially during the earlier time period f1 and f2 whereas climate related effects appear to have dominated more recently f3 and f4 sedimentary aggradation is likely to have predominated during interglacial periods while interglacial glacial transitions when climate fluctuated are seen as times of increased incision previous correlations of the f1 f4 fluvial deposits with similar deposits elsewhere in cyprus including coastal marine carbonate deposits suggest that the f1 and f2 deposits are likely to be of middle pleistocene age and the f3 f4 deposits of late pleistocene to holocene age