transition from a singly vergent to doubly vergent wedge in a young orogen the greater caucasus the greater caucasus mountains due to their youth 5 ma provide an opportunity for insight into the early stages of orogen development during continent continent collision however their recent tectonic evolution and first order architecture remain unclear here we investigate the evolution of the orogen by integrating new observations of the fluvial geomorphology and neotectonics of the range with prior work on seismicity geodetic strain bedrock geology and foreland basin structure we find that the range contains four zones along strike that differ in structural architecture topography and first order tectonic history in particular two south directed singly vergent zones at the western and eastern tips of the orogen are separated by both a central doubly vergent zone that is dominated by north directed deformation and an eastern doubly vergent zone in which south directed thrusting dominates we hypothesize that the along strike changes in vergence and locus of deformation reflects different stages in the development of a doubly vergent orogen with the tips of the range preserving an early singly vergent form and the center recording a more advanced orogen the differences between the two doubly vergent zones seem to be driven by the initial stages of collision between the structurally thickened crust of the greater and lesser caucasus orogens which initiated at 5 ma

a record of holocene climate change from lake geochemical analyses in southeastern arabia lacustrine sediments from southeastern arabia reveal variations in lake level corresponding to changes in the strength and duration of indian ocean monsoon iom summer rainfall and winter cyclonic rainfall the late glacial holocene transition of the region was characterised by the development of mega linear dunes these dunes became stabilised and vegetated during the early holocene and interdunal lakes formed in response to the incursion of the iom at approximately 8500 cal yr bp with the development of c3 dominated savanna grasslands the iom weakened ca 6000 cal yr bp with the onset of regional aridity aeolian sedimentation and dune reactivation and accretion despite this reduction in precipitation the lake was maintained by winter dominated rainfall there was a shift to drier adapted c4 grasslands across the dune field lake sediment geochemical analyses record precipitation minima at 8200 5000 and 4200 cal yr bp that coincide with bond events in the north atlantic a number of these events correspond with changes in cultural periods suggesting that climate was a key mechanism affecting human occupation and exploitation of this region

climatic versus tectonic control on river incision at the margin of ne tibet 10be exposure dating of river terraces at the mountain front of the qilian shan 1 we document late pleistocene holocene aggradation and incision processes at the mountain front of the qilian shan an active intracontinental fold and thrust belt accommodating a significant portion of the india asia convergence the shiyou river cuts through a nne vergent fault propagation fold with miocene red beds in the core and pliocene quaternary growth strata on the northern forelimb south of the anticline miocene strata dip 20 ssw suggesting a similar orientation for the basal decollement after aggradation of an 150 m thick late pleistocene valley fill the shiyou river formed three terraces the highest terrace located 170 m above the river constitutes the top of the fill the other terraces are fill cut terraces their treads are located 130 105 m and 37 m above the river respectively the 10be exposure dating of the terraces suggests that river incision accelerated from 0 8 0 2 mm yr 1 to 10 mm yr 1 at 10 15 kyr we interpret fast holocene river incision as largely unrelated to tectonic forcing the late pleistocene incision rate of 0 8 0 2 mm yr 1 places an upper limit of 2 2 0 5 mm yr 1 on the horizontal shortening rate assuming that incision is solely caused by rock uplift above a decollement dipping 20 however the actual shortening rate may lie between 2 2 mm yr 1 and zero because deformation of the terraces and the valley fill cannot be unequivocally demonstrated our estimate is consistent with the bulk shortening rate of 5 10 mm yr 1 across several faults in ne tibet derived from neotectonic and gps data although in case of the shiyou river holocene deformation is barely discernible owing to intense climate induced river incision

western mediterranean environmental changes evidences from fluvial archives abstract when dealing with current and past landscape evolution a key issue addresses responses of geomorphic systems to the large number of influencing variables identifying morphodynamic phases and revealing interrelations with specific driving forces are demanding tasks for quaternary research in this paper we present late pleistocene and holocene fluvial sedimentation patterns of three western mediterranean river catchments namely jarama river guadalete river and guadalquivir river that extent along a climatic transect from semi humid sw spain to semi arid central spain these studies are based on extensive fieldwork conducted on 36 exposures and 13 drillings in floodplain positions field data is supported by geochemical analyses while the chronological framework was obtained from the analyses of 70 radiocarbon samples results show distinct patterns of fluvial sedimentation as well as soil formation linked to floodplain stability for each river catchment on regional or catchment scale pollen stratigraphical correlation and comparison with lacustrine records show that fluvial dynamics have a strong reaction to climatic shifts with phases of high fragility characterized by catchment erosion and floodplain sedimentation in response to climatic aridification events and phases of climate change in general the comparison of the examined river systems reveals that periods of supra regional floodplain sedimentation in several catchments occurred from 8 0 to 7 0 5 0 to 3 8 2 2 to 1 5 and around 1 0 as well as 0 4 ka cal bp while we found periods of supra regional soil formation from 13 3 to 12 7 7 0 to 5 1 with a short interruption around 6 0 to 5 5 ka 2 8 to 2 3 ka 1 4 to 1 2 ka and 0 8 to 0 5 ka cal bp beside these consistencies we found deviating dynamic patterns that are apparently expressed in terms of differing onset and offset differing durations or even the lack of fluvial system response the main reasons for this can be seen in different regional climate condition and impacts of further influencing factors or in different levels of sensitivity of the river catchments that may be controlled by initial hydrological conditions catchment size or the degree of anthropogenic influence a larger scale assessment shows that fluvial dynamic patterns are hardly comparable across entire spain due to strong spatial heterogeneity of physiographic and climatic conditions on the iberian peninsula in particular when areas are influenced by different circulation systems e g regions influenced by the atlantic ocean vs regions influenced by the mediterranean sea however the consideration of north atlantic marine records reveals a certain coupling between north atlantic coolings atmospheric processes leading to arid climate over large parts of spain as well as increased landscape instability including strong fluvial sedimentation activity attendant atmospheric conditions are discussed

holocene climate variability and change a data based review the holocene thermal maximum with peak temperatures prior to 7 ka bp is mostly accentuated in the northern hemisphere still visible in the southern hemisphere and possibly did not exist in the tropics between this period and the modern warming a remarkable negative temperature trend occurred in the northern hemisphere which was probably the effect of a decreasing orbital induced insolation during the boreal summer on average the northern hemisphere humidity precipitation records do not show any significant trend a mechanistic explanation for the multi decadal to century scale holocene cold relapses which mainly occurred in the atlantic european regions exists for only the early holocene cooling events which are probably the result of a collapse of the meridional overturning circulation owing to freshwater outbursts from the laurentide ice sheet possibly the late holocene cold events after c 4 ka bp are influenced by the covarying influence of major tropical volcanic eruptions and grand solar minima

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

north atlantic influence on holocene flooding in the southern greater caucasus in the context of global climate change flooding becomes an increasingly serious threat to modern societies and future flooding can only be understood using long term geological flood records als

testing solar forcing of pervasive holocene climate cycles the temporal and spatial extent of holocene climate change is an area of considerable uncertainty with solar forcing recently proposed to be the origin of cycles identified in the north atlantic region to address these issues we have developed an annually resolved record of changes in irish bog tree populations over the last 7468 years which together with radiocarbon dated bog and lake edge populations extend the dataset back to 9000 yr ago the irish trees underpin the internationally accepted radiocarbon calibration curve used to derive a proxy of solar activity and allow us to test solar forcing of holocene climate change tree populations and age structures provide unambiguous evidence of major shifts in holocene surface moisture with a dominant cyclicity of 800 yr similar to marine cycles in the north atlantic indicating significant changes in the latitude and intensity of zonal atmospheric circulation across the region the cycles however are not coherent with changes in solar activity both being on the same absolute timescale indicating that holocene north atlantic climate variability at the millennial and centennial scale is not driven by a linear response to changes in solar activity copyright 2005 john wiley sons ltd

potential influence of bond events on mid holocene climate and vegetation in southern pyrenees as assessed from burg lake loi and pollen records superimposed on the long term climate variability attributed to orbital forcing there are other modes of variability covering timescales from interannual to millennial throughout the holocene their signatures in climate proxy archives can differ substantially because of their lower magnitude and regional diversity however if identified they can yield better understanding of the physical mechanisms regionally linking causes and effects here we describe a high resolution record of organic matter accumulation in the sediments of burg lake pyrenees ne iberian peninsula as assessed using loss on ignition loi and compare it with the ice rafted debris ird indexes from the north atlantic the loi record indicates two main phases in the water body a lacustrine phase as a shallow lake and a palustrine phase as a fen the latter covers the period 2600 7200 cal yr bp and within it there is a high coherence between loi and ird which indicates submillennial climate fluctuations in the pyrenees that can

vegetation fire and climate history of the lesser caucasus a new holocene record from zarishat fen armenia vegetation fire and climate history are investigated in the 10 000 year record of zarishat fen located today in the steppe grasslands of armenia near east pollen based climate quantification provides a reconstruction of seasonal parameters the development of in situ water dependant plants and of forests at lower altitude at 8200 cal a bp echoes the shift from an arid and cold annual precipitation pann 452mm mean temperature of the coldest month mtco 11 1uc early holocene to a more humid and warmer pann 721mm mtco 6 8uc mid late holocene this marks the onset of lower seasonality in particular more effective precipitation brought during late spring by the westerlies paralleling the mediterranean precipitation pattern precipitation in the near east and central asia decreased during the mid late holocene in favour of higher seasonality controlled in winter spring by the siberian high fire history and sedge based fen development record drier phases at approximately 6400 5300 4900 3000 2200 1500 and 400 cal a bp which resemble the precipitation pattern of the south western mediterranean and contrast with the holocene pattern in the south central and south eastern mediterranean regions arid phases in armenia are believed to be related to multi centennial scale variation of westerly activity north atlantic oscillation like copyright 2013 john wiley sons ltd

geomorphic response and 14c chronology of base level changes induced by late quaternary caspian sea mobility middle kura valley azerbaijan abstract recent geomorphological studies in azerbaijan reveal the importance of climato eustatic influences on landscape changes in the caspian sea basin during the last 40 ka radiocarbon dated fluvial landforms show that the paleohydrosystem of the middle kura valley and tributaries responded to regressive and transgressive phases of the caspian sea chrono sequences and landforms secured by 32 radiocarbon ages show strong correspondence between fluvial sediment accumulation and oscillations of base level in the caspian sea six phases of valley floor aggradation e g 27 000 13 000 11 000 3200 2900 2100 1600 1000 400 150 cal yr bp and seven phases of fluvial incision 37 000 37 000 27 000 13 000 11 000 3200 2900 2100 1600 1000 400 150 0 cal yr bp are recorded morphodynamics of the fluvial landscape show a strong correspondence with fluctuation in sea levels in the caspian sea the major upper pleistocene late glacial khvalynian c a 26 000 to 12 400 cal yr bp and various holocene transgressions as well as the mangyshlak c a 12 000 cal yr bp and derbent 6th 12th century ad regressions these data contribute to refining the caspian relative sea level curve for the last 30 ka using the chronology of changes in the aggradation or incision in the connected fluvial system

abrupt climate variability since the last deglaciation based on a high resolution multi proxy peat record from nw iran the hand that rocked the cradle of civilization abstract we present a high resolution sub decadal to centennial multi proxy reconstruction of aeolian input and changes in palaeohydrological conditions based on a 13000 yr record from neor lake s peripheral peat in nw iran variations in relative abundances of refractory al zr ti and si redox sensitive fe and mobile k and rb elements total organic carbon toc 13 c toc compound specific leaf wax hydrogen isotopes d carbon accumulation rates and dust fluxes presented here fill a large gap in the existing terrestrial paleoclimate records from the interior of west asia our results suggest that a transition occurred from dry and dusty conditions during the younger dryas yd to a relatively wetter period with higher carbon accumulation rates and low aeolian input during the early holocene 9000 6000 yr bp this period was followed by relatively drier and dustier conditions during middle to late holocene which is consistent with orbital changes in insolation that affected much of the northern hemisphere numerous episodes of high aeolian input spanning a few decades to millennia are prevalent during the middle to late holocene wavelet analysis of variations in ti abundances as a proxy for aeolian input revealed notable periodicities at 230 320 and 470 years with significant periodicities centered around 820 1550 and 3110 years over the last 13000 years comparison with palaeoclimate archives from west asia the north atlantic and african lakes point to a teleconnection between north atlantic climate and the interior of west asia during the last glacial termination and the holocene epoch we further assess the potential role of abrupt climate change on early human societies by comparing our record of palaeoclimate variability with historical geological and archaeological archives from this region the terrestrial record from this study confirms previous evidence from marine sediments of the arabian sea that suggested climate change influenced the termination of the akkadian empire in addition nearly all observed episodes of enhanced dust deposition during the middle to late holocene coincided with times of drought famine and power transitions across the iranian plateau mesopotamia and the eastern mediterranean region these findings indicate that while socio economic factors are traditionally considered to shape ancient human societies in this region the influence of abrupt climate change should not be underestimated

fluvial sediments of the algeti river in southeastern georgia an archive of late quaternary landscape activity and stability in the transcaucasian region abstract in order to obtain information about landscape activity and stability during the late quaternary in the transcaucasian region fluvial sediments of the lower algeti river in se georgia were studied by means of geomorphologic sedimentologic and geochronologic methods these investigations show that sediments aggraded by the late pleistocene braided algeti river were strongly incised around the pleistocene holocene transition and subsequently a small scale pattern of diachronous fluvial terraces deposited by the now meandering river developed in the new valley during the holocene prior to ca 3 cal ka bp active phases of river channel aggradation and overbank sedimentation about 6 cal ka bp and 3 4 3 2 cal ka bp can be linked with climate driven vegetation changes i e stronger fluvial dynamics with sedimentation occurred during more arid and colder periods whereas the caucasian holocene climate optimum between 6 and 3 4 cal ka bp was characterized by stable geomorphologic conditions after 3 cal ka bp strongly increased human impact documented by former pollen studies is reflected by the fluvial dynamics as well i e an activity phase of strong overbank sedimentation 2 7 2 1 cal ka bp occurred during a period when forests in the lesser caucasus were burnt down two subsequent activity phases with fluvial sedimentation can be linked with historic events that probably both influenced vegetation distribution of the region i e a period of flourishing of georgia during the middle age and a time of large scale destruction of the country due to a persian invasion at the end of the 18th century ad respectively thus whereas no influence of tectonic events or fluctuations of the caspian sea level on the fluvial dynamics could be detected se georgia shows its fragile character with respect to climate and human driven vegetation changes similar to other semi arid landscapes of the mediterranean region

strontium isotope systematics of hydrothermal vein minerals in deposits of west germany vein minerals in west germany hosted by crystalline basement rocks and paleozoic and mesozoic sedimentary rocks are characterized by87sr 86sr ratios which indicate continental derivation of sr incorporated into the minerals neither mantle derived sr nor prominent contribution of this element from sea water except for the strontianites of munsterland can be substantiated by the data presented

geomorphic and sedimentary response of rivers to tectonic deformation a brief review and critique of a tool for recognizing subtle epeirogenic deformation in modern and ancient settings abstract rivers are extremely sensitive to subtle changes in their grade caused by tectonic tilting as such recognition of tectonic tilting effects on rivers and their resultant sediments can be a useful tool for identifying the often cryptic warping associated with incipient and smaller scale epeirogenic deformation in both modern and ancient settings tectonic warping may result in either longitudinal parallel to floodplain orientation or lateral normal to floodplain orientation tilting of alluvial river profiles alluvial rivers may respond to deformation of longitudinal profile by 1 deflection around zones of uplift and into zones of subsidence 2 aggradation in backtilted and degradation in foretilted reaches 3 compensation of slope alteration by shifts in channel pattern 4 increase in frequency of overbank flooding for foretilted and decrease for backtilted reaches and 5 increased bedload grain size in foretilted reaches and decreased bedload grain size in backtilted reaches lateral tilting causes down tilt avulsion of streams where tilt rates are high and steady down tilt migration combing where tilt rates are lower each of the above effects may have profound impacts on lithofacies geometry and distribution that may potentially be preserved in the rock record fluvial sedimentary evidence for past tilting is traditionally based on the assumption that depositional features reminiscent of modern fluvial tectonic effects are evidence for past tectonic effects where it is closely associated with historically active structures or where non tectonic causes cannot be invoked however caution must be exercised when using these effects as criteria for past or current tectonic warping as these effects may be caused by non tectonic factors these non tectonic causes must be eliminated before tectonic interpretations are made

gps constraints on continental deformation in the africa arabia eurasia continental collision zone and implications for the dynamics of plate interactions 1 the gps derived velocity field 1988 2005 for the zone of interaction of the arabian african nubian somalian and eurasian plates indicates counterclockwise rotation of a broad area of the earth s surface including the arabian plate adjacent parts of the zagros and central iran turkey and the aegean peloponnesus relative to eurasia at rates in the range of 20 30 mm yr this relatively rapid motion occurs within the framework of the slow moving 5 mm yr relative motions eurasian nubian and somalian plates the circulatory pattern of motion increases in rate toward the hellenic trench system we develop an elastic block model to constrain present day plate motions relative euler vectors regional deformation within the interplate zone and slip rates for major faults substantial areas of continental lithosphere within the region of plate interaction show coherent motion with internal deformations below 1 2 mm yr including central and eastern anatolia turkey the southwestern aegean peloponnesus the lesser caucasus and central iran geodetic slip rates for major block bounding structures are mostly comparable to geologic rates estimated for the most recent geological period 3 5 myr we find that the convergence of arabia with eurasia is accommodated in large part by lateral transport within the interior part of the collision zone and lithospheric shortening along the caucasus and zagros mountain belts around the periphery of the collision zone in addition we find that the principal boundary between the westerly moving anatolian plate and arabia east anatolian fault is presently characterized by pure left lateral strike slip with no fault normal convergence this implies that extrusion is not presently inducing westward motion of anatolia on the basis of the observed kinematics we hypothesize that deformation in the africa arabia eurasia collision zone is driven in large part by rollback of the subducting african lithosphere beneath the hellenic and cyprus trenches aided by slab pull on the southeastern side of the subducting arabian plate along the makran subduction zone we further suggest that the separation of arabia from africa is a response to plate motions induced by active subduction

holocene river activity analysing 14c dated fluvial and colluvial sediments from germany records of fluvial dynamics in response to long term changes of climate and land use impacts are rare therefore cumulative probability functions cpfs of 401 14c ages originating from german rivers and hillslopes were compiled to reconstruct phases of increased geomorphic activity and stability during the holocene an improved analytical method is suggested to normalise cpfs and eliminated the effects of wiggles of the calibration curve and the young age bias nine periods of activity are identified peaking at 7050 6250 5525 3690 2250 1350 820 325 bc and since 875 ad and are compared with climatic palaeohydrological and human impact proxy data until 2250 bc events of geomorphic activity are mainly coupled to wetter and or cooler climatic phases due to growing population and intensive agricultural activities during the bronze age the increased geomorphologic activity between 1300 and 820 bc cannot unequivocally be related to climate since 875 ad the growing population density is considered as the major external forcing differential geomorphic activity of hillslopes and floodplains suggest that the hillslope channel coupling during the holocene is mainly controlled by human impact with a strong increased coupling after 1500 bc

a 500 yr speleothem derived reconstruction of late autumn winter precipitation northeast turkey a verified instrumental calibration of annually resolved 18o for a stalagmite from gumushane in northeast turkey is presented and cross validated using a leave one out technique the amount of late autumn to winter precipitation is negatively correlated with stalagmite 18o between ad 1938 and 2004 the observed relationship is extrapolated back to ad 1500 leading to the first long winter precipitation reconstruction for this region modern day october to january precipitation is linked to pressure fields in western russia anomalously lower reconstructed rainfall is recorded in ad 1540 1560 at which time higher pressure over the caspian sea region is inferred

late cenozoic deformation of the kura fold thrust belt southern greater caucasus although the geometry and kinematics of the first order structures accommodating arabia eurasia convergence are relatively well known in turkey and iran major shortening structures remain poorly understood within the central portion of the collision zone in eastern anatolia and the caucasus new remotely sensed neotectonic mapping synthesis of regional geologic and stratigraphic data and balanced cross sections suggest that the kura fold thrust belt has accommodated the majority of arabia eurasia convergence since the early pliocene between the longitudes of 45 e and 49 e this belt lies southeast of the n80 w striking greater caucasus mountains and forms an eastward narrowing band of elevated topography that roughly parallels the range front for 400 km along strike the belt is separated from the greater caucasus to the north by the 10 to 25 km wide alazani basin and comprises a series of predominantly south verging folds deforming eocene quaternary flysch and molasse to document structural geometries within the kura fold thrust belt we have used the real time interactive mapping system rims software to analyze advanced spaceborne thermal emission and reflection radiometer aster visible to near infrared vnir and digital elevation model dem data this neotectonic mapping indicates an along strike eastward decrease in both structural complexity and the degree to which deformed geomorphic surfaces are dissected existing geologic maps indicate a corresponding eastward decrease in the depth of exposure by integrating the structural geometries determined in our analysis of remote sensing data with existing geologic data we have constructed two balanced cross sections which suggest these systematic along strike variations result from a west to east decrease in total shortening within the kura fold thrust belt we interpret this variable shortening to stem from eastward propagation of the kura fold thrust belt comparison of our preliminary total shortening estimates with those predicted by current plate motions suggest that the kura fold thrust belt has accommodated 30 40 25 km of total arabia eurasia convergence since 5 ma and thus forms a first order structural system within the central portion of the collision zone

past hydrological events reflected in holocene history of polish rivers abstract a database of 335 radiocarbon dates from holocene fluvial sediments in poland has been compiled each sample is characterized by 25 parameters all samples were grouped into one of 7 regions characterized by hydrological regime and one of 8 depositional environments statistical analysis was used to enhance the palaeoenvironmental data and 17 phases may be distinguished 10 of which have a distinct sharp peak abandoned paleochannels 149 dates clearly reflect the major wetter phases of the holocene an opposite picture is presented by overbank aggradation 86 dates connected mainly with expansion of agriculture preliminary correlations are made on peat bog records changes in vegetation lake water level rates calcareous tufa and speleothems growth landslides phases and debris flow phases these show many convergences explained by climatic fluctuations during the holocene