chronology of late wisconsinan glaciation in middle north america abstract we propose a chronology of late wisconsinan glacial fluctuations in middle north america from alberta to wisconsin based on radiocarbon dates derived solely from wood previous chronologies of the southwestern margin of the north american continental ice sheet have depended to a considerable degree on radiocarbon dates from fine grained organic sediment this material is commonly contaminated with older carbon resulting in chronologic confusion by using only dates from wood much of the confusion disappears however because of the scarcity of wood dates only four of the sixteen identified fluctuations are accurately dated an advance into iowa about 14 000 to 13 500 bp an advance into south dakota and iowa about 12 300 bp an advance into the lake michigan basin about 11 700 bp and an advance into the lake superior basin about 9900 bp in addition the beginning of late wisconsinan glaciation before 20 000 bp is fairly well documented none of the fluctuations in the western part of the region are accurately dated

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

the pliocene initiation and early pleistocene volcanic disruption of the palaeo gediz fluvial system western turkey in this paper we report our latest observations concerning a pliocene and early pleistocene record from western turkey the sedimentary sequence described comprises the fluvial deposits of an early pleistocene palaeo gediz river system and its tributaries prior to the onset of volcanism around kula and the subsequent lacustrine volcaniclastic and fluvial deposits associated with the first phase of volcanism similar to 1 2 ma in this area early development of an east west drainage system in this area resulted from tectonic adjustments to north south extension and the formation of east west oriented grabens headward erosion of drainage entering the main alasehir graben led to the progressive capture of pre existing drainage systems as eastward headward erosion upstream tapped drainage networks previously formed in internally draining nne ssw oriented basins within one of these the selendi basin part of this evolutionary sequence is preserved as a buried river terrace sequence eleven terraces are preserved beneath alluvial fan sediments that are in turn capped by basaltic lava flows using the available geochronology these terraces are considered to represent sedimentation incision cycles which span the period similar to 1 67 1 2 ma although progressive valley incision is a fluvial system response to regional uplift the frequency of terrace formation within this time period suggests that the terrace formation resulted from sediment water supply changes a consequence of obliquity driven climate changes the production of sub parallel terraces suggests that during this period the river was able to attain a quasi equilibrium longitudinal profile adjusted to the regional uplift rate thus the incision rate of 0 16 mm a 1 during this period is believed to closely mirror the regional uplift rate after the onset of volcanism at similar to 1 2 ma there is a destruction of the dynamic link between fluvial system behaviour and climate change the repeated damming of the trunk river and its tributaries led to the construction of complex stratigraphic relationships during the first phase of volcanism the palaeo gediz river was dammed on numerous occasions leading to the formation of a series of lakes upstream of the dams in the palaeo gediz valley variations in lake level forced localised base level changes that resulted in complex fluvial system response and considerable periods of disequilibrium in profile adjustment furthermore response to these base level changes most likely disrupted the timing of the incisional adjustment to the on going regional uplift thus making the use of this part of the archive for inferring regional uplift rates untenable c 2007 elsevier ltd all rights reserved

southern laurentide ice lobes were created by ice streams des moines lobe in minnesota usa abstract regional mapping in southern minnesota has illuminated a suite of landforms developed by the des moines lobe that delimit the position of the lobe at its maximum and at lesser readvances the ice lobe repeatedly advanced discharged its subglacial water and subsequently stagnated recent glaciological research on antarctic ice streams has led some glacial geologists to postulate that ice streams drained parts of the marine based areas of the laurentide ice sheet i postulate that such ice streams may develop in land based areas of an ice sheet as well and that the des moines lobe 200 km wide and 900 km long was an outlet glacier of an ice stream it appears to have been able to advance beyond the laurentide ice sheet as long as adequate water pressure was maintained however the outer part of the lobe stagnated because subglacial water that facilitated the flow was able to drain away through tunnel valleys stagnation of the lobe is not equivalent to stoppage of the ice stream because ice repeatedly advanced into and onto the stagnant margins stacking ice and debris similar landforms are also seen in other lobes of the upper midwestern united states

cosmic ray labeling of erosion surfaces in situ nuclide production rates and erosion models a number of in situ cosmogenic radionuclides and stable nuclides have been measured in natural exposed rock surfaces with a view to study their in situ production and rock erosion rates 1 the in situ radionuclides can be used for a high resolution tomography of the erosional history of an exposed surface two stable nuclides 3he 21ne and five radionuclides 10be 26al 36cl 14c 39ar having half lives in the range of 300 1 5 106 yr half life are measurable in many rock types a prerequisite for the application of the in situ nuclides for the study of erosional histories of surfaces is a knowledge of their production rates under different irradiation conditions altitude latitude irradiation geometry and shielding relative nuclide production rates can be determined fairly accurately using the extensive available data on cosmic ray neutrons 2 absolute nuclide production rates cannot generally be predicted with any accuracy because of lack of data on excitation functions of nuclides unless some normalization is possible as was done in the case of several cosmic ray produced isotopes in the atmosphere 3 based on a recent natural calibration experiment in which erosion free surfaces exposed to cosmic radiation for 11 000 yrs were sampled the absolute production rates of 10be and 26al in quartz have been accurately estimated for mountain altitudes in sierra nevada 4 the absolute production rates of 10be and 26al in quartz can therefore be estimated fairly accurately for any given latitude and altitude some measurements of 14c in rocks of low erosion rate 5 similarly allow an estimate of its production rate attempts made to measure the in situ production rates of 3he in rocks have not yet led to a convergent production rate in view of the importance of knowing the production rates of isotopes of he ne and ar i present here theoretical estimates of their production rates based on available cross section data i discuss the information that can be extracted from the study of the in situ nuclides in rocks useful parameters characterizing the exposure history of a rock surface are 1 the effective surface exposure age and 2 the time averaged erosion rate the implications of these parameters for single and multiple nuclide studies are discussed in terms of the erosion models considered

catchment response to lava damming integrating field observation geochronology and landscape evolution modelling combining field reconstruction and landscape evolution modelling can be useful to investigate the relative role of different drivers on catchment response the geren catchment 45 km2 in western turkey is suitable for such a study as it has been influenced by uplift climate change and lava damming four middle pleistocene lava flows 40ar 39ar dated from 310 to 175 ka filled and dammed the gediz river at the gediz geren confluence resulting in base level fluctuations of the otherwise uplift driven incising river field reconstruction and luminescence dating suggest fluvial terraces in the geren catchment are capped by middle pleistocene aggradational fills this showed that incision of the geren trunk stream has been delayed until the end of mis 5 subsequently the catchment has responded to base level lowering since mis 4 by 30 m of stepped net incision field reconstruction left us with uncertainty on the main drivers of terrace formation therefore we used landscape evolution modelling to investigate catchment response to three scenarios of base level change i uplift with climate change rainfall and vegetation based on arboreal pollen ii uplift climate change and short lived damming events iii uplift climate and long lived damming events outputs were evaluated for erosion aggradation evolution in trunk streams at two different distances from the catchment outlet climate influences erosion aggradation activity in the catchment although internal feedbacks influence timing and magnitude furthermore lava damming events partly control if and where these climate driven aggradations occur damming thus leaves a legacy on current landscape evolution catchment response to long duration damming events corresponds best with field reconstruction and dating the combination of climate and base level explains a significant part of the landscape evolution history of the geren catchment by combining model results with fieldwork additional conclusions on landscape evolution could be drawn

cold based laurentide ice covered new england s highest summits during the last glacial maximum to better understand glacial history and process in new england northeastern united states a mountainous area overrun by the laurentide ice sheet we measured three cosmogenic nuclides in nine upland samples the concentrations of 10be and 26al in some samples collected near the summits of katahdin maine and mount washington and little haystack mountain new hampshire are 2 10 times higher than expected for a single exposure period considering field evidence indicating that continental ice covered all new england peaks during the last glacial maximum in situ 14c exposure ages from the summits are much younger suggesting that high elevation sampling sites were ice covered before and during the last glacial maximum field and isotopic data are consistent with new england summits being covered in part by cold based continental ice that did not erode much rock the contrast in erosion rates between stable summits and deeply eroded valleys likely contributes to the development and maintenance of northern appalachian topography

age of the pineo ridge system implications for behavior of the laurentide ice sheet in eastern maine u s a during the last deglaciation abstract the laurentide ice sheet was a major driver of global sea level change during the last deglaciation and may have impacted both atmospheric and oceanic circulation an understanding of past changes in the ice sheet is important for constraining its interaction with other components of the climate system here we present the geologic context and chronology for ice sheet fluctuations in eastern maine adjacent to the north atlantic ocean thought to be a key player in the termination of the last ice age retreat of the laurentide ice sheet through coastal maine first produced a series of lobate grounding line moraines followed by deposition of the prominent pineo ridge system which crosscut the earlier moraine set and which is characterized by extensive ice contact deltas closely spaced parallel moraines and association with eskers our new 10 be surface exposure ages indicate that the pineo ridge system which extends for more than 100 km in eastern maine and atlantic canada dates to 15 3 ka 800 years older than recent estimates our data are in accord with inboard minimum limiting radiocarbon ages of terrestrial materials which indicate deglaciation as early as 15 3 ka as well as of marine shells that are as old as 15 0 ka both the deglaciation that produced the lobate moraines and the short lived readvance that led to the pineo ridge system occurred during heinrich stadial 1 given that faunal and isotopic evidence indicates that the ocean remained cold during deglaciation of coastal maine we infer that ice recession was due to rising summer air temperatures that gave way briefly to cooling to allow minor readvance glacial deposits north of the pineo ridge system display evidence of ice stagnation and downwasting suggesting rapid ice retreat following deposition of the delta moraine complex coincident with the onset of the bolling

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

interaction of fluvial and eolian sedimentation processes and response to climate change since the last glacial in a semiarid environment along the yellow river interactions of fluvial and eolian processes are prominent in dryland environments and can significantly change earth surface morphology here we report on sediment records of eolian and fluvial interactions since the last glacial period in the semiarid area of northwest china at the limit of the southeast asian monsoon sediment sequences of last glacial and holocene terraces of the yellow river are composed of channel gravels overlain by flood sands eolian dunes and flood loams these sequences dated by optically stimulated luminescence record interlinks between fluvial and eolian processes and their response to climate change sedimentologic structures and grain size analysis show flood loams consisting of windblown sediment deposited from floodwater suspended sediment the gravel and sand were deposited during cold periods during transitions from cold to warm phases the river incised and dunes were formed by deflation of channel and floodplain deposits 70 and 21 16 ka dunes also formed at 0 8 ka probably after human intervention after dune formation flood loam covered dunes without erosion during peak discharges at the beginning of the subsequent warm period the fluctuations of the southeast asian monsoon as a moisture transporting agent have perhaps been the driving force for interactions between fluvial and eolian processes in this semiarid environment

rayleigh waves guided by sea trench topography a later phase of large amplitude is observed at a station in hokkaido from several events of the december 1991 off urup earthquake swarm in the kurile islands region the phase is characterized by a narrow frequency band with a dominant period of about 15 s and retrograde particle motion in a vertical plane with a strike very different from the great circle direction between the station and the epicenter the phase is observed from only the earthquakes that are located at shallow depths beneath the inner wall of the kurile trench where sea depth is greater than 4 km these characteristics indicate that the phase is a packet of rayleigh waves that arrive at the station from an azimuth considerably different from the great circle direction rayleigh waves with periods around 15 20 s are well excited by the shallow earthquakes beneath the inner wall of the trench this is supported by the dominance of a spectral peak at 15 20 s in the spectra of the direct rayleigh waves and the later phase rayleigh waves that propagate in an oceanic region are strongly influenced by the thickness of the water layer at periods shorter than about 25 s the group velocity decreases by 80 at 15 s with the increase of the sea depth from 4 km to 6 km the sea trench topography therefore forms a strong low velocity zone the observed later phase can be interpreted as a rayleigh wave packet guided by this velocity complexity

chronology of the yellow river terraces at qingtong gorge ne tibet insights into evolution of the yellow river since the middle pleistocene abstract the formation and abandonment of fluvial terraces provide key records of past climatic changes and regional tectonics that reflect the evolution of rivers at the northeastern periphery of the tibetan plateau the yellow river flows through the qingtong gorge a deep canyon incised through the niushou shan a flight of 8 fluvial terraces preserved along the canyon four of which t2 t3 t6 and t8 were dated using osl and cosmogenic nuclide exposure dating the results show that the four terraces were formed at 51 6 2 9 ka 60 7 14 4 8 3 ka 346 1 30 27 3 ka and 580 640 ka respectively precise measurement of terrace heights suggests that the average incision rate of the yellow river over the past 350 ka was 200 m ma and increased significantly in the past 60 ka analysis of the relationship between the observed incision histories with regional climatic records and local tectonics suggests that climatic variations since the late quaternary drove cutting and abandonment of the terraces during progressive tectonic growth of the niushou shan our results provide constraints on the timing of incision and linkage of various segments of the modern yellow river fluvial network

the early pleistocene development of the gediz river western turkey an uplift driven climate controlled system this paper reports the latest details from an on going investigation of the early pleistocene buried river terrace sequence of the gediz river 40 km upstream of the alasehir graben in the kula volcanic province western turkey using clast lithology to characterise sediment provenance we demonstrate that the buried early pleistocene terrace sequence of the palaeo gediz is overlain by the deposits of two carbonate rich northerly derived tributary systems the surface form of these carbonate rich deposits suggests deposition on alluvial fans an interpretation supported by limited palaeocurrent data and upwards coarsening sequences suggesting fan progradation it is argued that the formation and preservation of the palaeo gediz terrace sequence is intimately related to fan deposition fan head entrenchment and fan progradation terrace formation is the result of incision in the main gediz valley a response to long term uplift during periods of lower sediment supply under low sediment supply conditions inferred fan head entrenchment is associated with fan toe progradation this progradation would have led to the burial of the newly formed terrace of the gediz subsequent higher sediment supply conditions would have led to renewed fan deposition the direct coupling of the fan system with the main gediz river during these periods would also result in deposition within the trunk river the primary control of sediment supply is considered here to reflect changing vegetation cover a function of changing quaternary climates these inferred controls suggest that the gediz early pleistocene terrace sequence is an uplift driven climate controlled system

volcanic eruption eye witnessed and recorded by prehistoric humans abstract human footprints in hydrovolcanic ash near cakallar volcano kula western turkey were discovered in 1968 a nearby pictograph interpreted as depicting cakallar volcano would define it as the oldest site where humans demonstrably eye witnessed a volcanic eruption and possibly artistically recorded it despite cakallar s volcanological and cultural importance its eruption age has remained controversial here two independent dating methods cosmogenic 36cl and combined u pb and u th he zircon zdd geochronology yielded the first internally consistent eruption ages controlled by detailed volcanostratigraphic mapping concordant 36cl ages of 4 7 0 6 ka errors 1 were obtained for a cone breaching lava flow zdd ages for crustal xenoliths from scoria deposits directly overlying the footprints yielded an age of 4 7 0 7 ka this firmly places the cakallar eruption and prehistoric human footprints and plausibly the rock art into the bronze age reinforcing the notion that prehistoric artwork recorded natural events

volcanic disruption and drainage diversion of the palaeo hudut river a tributary of the early pleistocene gediz river western turkey abstract the importance of extrinsic drivers of fluvial system behaviour climate tectonics eustatic sea level over quaternary timescales is well documented however comparatively fewer studies have been reported concerning the significance of more localised changes at reach to sub catchment scale over these extended 10 4 10 6 years timescales in this paper we examine the early pleistocene sedimentary record of the palaeo hudut river and compare it with the record from the trunk river into which it drains the gediz river of western turkey both the gediz river and the hudut river were subjected to major localised disruption during the early pleistocene as a consequence of volcanism but their respective responses to these events appear to differ observations are reported from the sedimentary sequence buried beneath the lavas which cap the burgaz plateau these sediments record a remarkable amount of detail for a significant period of the early pleistocene these suggest that the palaeo hudut system responded largely to the creation and failure of downstream lava dams both through channel incision and subsequent filling and via route diversions around lava dams and their associated lakes in contrast the gediz terrace record appears to demonstrate a river which was able to accommodate these changes more readily and hence continue to undergo sedimentation incision cycles consistent with a climate forcing

resolving time space histories of late cenozoic bedrock incision along the upper colorado river usa abstract the upper colorado river basin drains the western slope of the rocky mountains province of north america and hosts a rich record of fluvial terraces and volcanic deposits that provide an archive of bedrock river incision since the late miocene here we present new geochronology from fluvial deposits and associated volcanic units using multiple methods luminescence cosmogenic burial 40ar 39ar basalt and detrital sanidine and u pb detrital zircon to reconstruct a detailed record of bedrock incision in the upper colorado river over timescales ranging from miocene to late pleistocene late miocene ca 11 8 ma basalt flows perched 800 1700 m above the colorado river and the oldest known ancestral colorado river deposits preserved beneath basalt flows on grand mesa provide the basis for average long term 107 yr incision rates rates range from 110 160 m ma between grand junction downstream and glenwood canyon upstream with rates decreasing upvalley intermediate scale 105 106 yr incision rates are 200 320 m m y over the past 1 3 ma and these rates are faster than the average over the past 8 11 ma short term

long term behaviour of continental hydrothermal systems u series study of hydrothermal carbonates from the french massif central allier valley abstract u series dating of hydrothermal carbonates deposited by co2 rich thermo mineral waters of the french massif central provides new insights on the long term behaviour of a continental hydrothermal system dating of aragonite veins and travertines impregnating old terrace levels of the allier river allowed identification of the main episodes of surface deposition and thus factors likely to influence these circulations fifteen layers from three veins and four travertines from two separate areas were analysed sr isotope compositions were also measured on vein samples the results show that this region was subjected to at least 3 main episodes of surface or near surface hydrothermal deposition 253 to 208 ky 135 to 100 ky and less than 8 ky comparison of these ages with a global climatic curve indicates that preferential deposition of carbonates occurs during warm periods suggesting a strong influence of climatic conditions on the hydrothermal system it is suggested that this climatic influence does not necessarily imply the absence of carbonate deposition during cold and dry periods but rather that carbonate precipitation might occur at depth before the geothermal fluids reach the surface in addition the isotope compositions of fluids recorded by the 87sr 86sr and 234u 238u initial ratios in the aragonite veins from coudes remained remarkably constant over 250 ky ranging from 0 71360 to 0 71371 and from 3 10 to 3 39 respectively the two samples coming from saladis show a slightly higher 234u 238u initial ratio around 3 95 the constancy of these ratios over such a long period suggests a hydrothermal system in a near steady state with respect to water rock interaction we thus propose a possible model allowing a conservative steady state despite variations in the water recharge rates in response to the climatic variations the difference between 234u 238u initial ratios measured in the coudes and saladis systems suggests the existence of two separate reservoirs and constrains their lateral extension to a few km at most

climate forcing of fluvial system development an evolution of ideas starting from traditional ideas on the climatic steering of fluvial system dynamics it appears that there are different kinds of climatic influences on system dynamics they vary from direct climatic forcing like peak precipitation to indirect like permafrost and partial forcing like vegetation vegetation or its absence and not directly climate is considered as the main cause of fluvial incision or deposition during temperate or cold periods however other external factors than climate and non climatic factors such as local basin characteristics like subsoil lithology and relief express their effects on the fluvial systems by their role in the energy balance of the river catchment finally internal factors in fluvial system evolution like thresholds and response time should not be neglected

pattern of southern laurentide ice sheet margin position changes during heinrich stadials 2 and 1 abstract with concerns over rising global temperatures ice sheet stability and implications for sea level rise the responses of former ice sheets to past climate change provide useful insights into linkages between the atmosphere cryosphere and oceans one example is the behavior of the laurentide ice sheet lis during heinrich stadials times of cooler sea surface temperature sst in the north atlantic using existing cosmogenic surface exposure ages varve chronologies radiocarbon ages and optically stimulated luminescence ages from the southern lis margin this report tests the hypothesis that the southern side of the lis advanced during times of surface cooling of the north atlantic this test reconstructs the timing of local glacial maxima and the times immediately pro and preceding them from multiple areas and compares them to the timing of heinrich stadial 2 hs2 26 6 23 6 ka and to the timing of heinrich stadial 1 hs1 19 3 15 3 ka during hs2 southern sector lobes new england region huron erie lobe lake michigan lobe green bay lobe and the chippewa lobe advanced towards their maximum position except for the des moines lobe for which there is no applicable data during hs1 these same lobes experienced substantial retreat but the des moines lobe advanced thus the southern laurentide margin behaved differently during the two heinrich stadials this pattern may be attributed to differing east west temperature gradients across north america and associated changes in atmospheric circulation

stratigraphic structural and geochemical features of the ne sw trending neogene volcano sedimentary basins in western anatolia implications for associations of supra detachment and transtensional strike slip basin formation in extensional tectonic setting western anatolia has been the focus of many geological studies of the classical extensional tectonics in the region the ne sw trending neogene volcano sedimentary basins that characterize western anatolia are mainly located on the northern part of the menderes massif a progressively exhumed mid crustal metamorphic unit that has undergone neogene extensional tectonics in the area the ne sw trending basins are the bigadic gordes demirci selendi emet gure and u ak basins although many studies have been carried out in these basins the stratigraphic and tectonic evolution of the ne sw trending volcano sedimentary basins remains controversial and hence different evolutionary models have been proposed by various authors recent studies concluded that there was a close relation in both space and time between the basin formation and the progressive exhumation of the menderes massif in this study we present new stratigraphic geochemical and tectonic observations from the gordes demirci and emet basins and couple them with data from the other ne sw trending basins to produce a tectono stratigraphic evolutionary model for the area gordes basin was opened by strike to oblique slip movements on the basin bounding faults as a result of dextral transtension such that the transtensional gordes basin formed where extension is oblique to the margin that bounded the basin the demirci selendi emet and gure basins have similar stratigraphic and tectonic features and began to develop as supra detachment extensional basins on an early miocene corrugated detachment fault the simav detachment fault sdf in these basins deposition of a middle miocene volcano sedimentary succession was controlled by ne sw trending strike to oblique slip faults which developed as accommodation faults in the hanging wall of a second detachment fault located further south the gediz detachment fault gdf these data suggest that the menderes massif was exhumed through basin formation in the upper plate that arose from successive detachment faulting accommodated by kinematically linked dextral strike to oblique slip motion to the west strike slip faulting is linked to a previously described crustal scale zone of weakness on which the gordes basin was formed the zmir bal kesir transfer zone the ne sw trending basins were also deformed by ne sw trending dextral and nw se trending sinistral strike slip faulting under pure shear during the late miocene and by e w trending dip slip normal faulting in the pliocene quaternary the data indicate that the region has been extended in a not vert similarn s direction since at least the early miocene and that this extension occurred episodically in several phases

the gediz river fluvial archive a benchmark for quaternary research in western anatolia abstract the gediz river one of the principal rivers of western anatolia has an extensive pleistocene fluvial archive that potentially offers a unique window into fluvial system behaviour on the western margins of asia during the quaternary in this paper we review our work on the quaternary gediz river project 2001 2010 and present new data which leads to a revised stratigraphical model for the early pleistocene development of this fluvial system in previous work we confirmed the preservation of eleven buried early pleistocene fluvial terraces of the gediz river designated gt11 the oldest and highest to gt1 the youngest and lowest which lie beneath the basalt covered plateaux of the kula volcanic province deciphering the information locked in this fluvial archive requires the construction of a robust geochronology fortunately the gediz archive provides ample opportunity for age constraint based upon age estimates derived from basaltic lava flows that repeatedly entered the palaeo gediz valley floors in this paper we present for the first time our complete dataset of 40ar 39ar age estimates and associated palaeomagnetic measurements these data which can be directly related to the underlying fluvial deposits provide age constraints critical to our understanding of this sequence the new chronology establishes the onset of quaternary volcanism at 1320ka mis42 this volcanism which is associated with gt6 confirms a pre mis42 age for terraces gt11 gt7 evidence from the colluvial sequences directly overlying these early terraces suggests that they formed in response to hydrological and sediment budget changes forced by climate driven vegetation change the cyclic formation of terraces and their timing suggests they represent the obliquity driven climate changes of the early pleistocene by way of contrast the gt5 gt1 terrace sequence constrained by a lava flow with an age estimate of 1247ka span the time interval mis42 mis38 and therefore do not match the frequency of climate change as previously suggested the onset of volcanism breaks the simple linkage of terracing to climate driven change these younger terraces more likely reflect a localized terracing process triggered by base level changes forced by volcanic eruptions and associated reactivation of pre existing faults lava dam construction landsliding and subsequent lava dammed lake drainage establishing a firm stratigraphy and geochronology for the early pleistocene archive provides a secure framework for future exploitation of this part of the archive and sets the standard as we begin our work on the middle late pleistocene sequence we believe this work forms a benchmark study for detailed quaternary research in turkey

improved moraine age interpretations through explicit matching of geomorphic process models to cosmogenic nuclide measurements from single landforms abstract the statistical distributions of cosmogenic nuclide measurements from moraine boulders contain previously unused information on moraine ages and they help determine whether moraine degradation or inheritance is more important on individual moraines here we present a method for extracting this information by fitting geomorphic process models to observed exposure ages from single moraines we also apply this method to 94 10 be apparent exposure ages from 11 moraines reported in four published studies our models represent 10 be accumulation in boulders that are exhumed over time by slope processes moraine degradation and the delivery of boulders with preexisting 10 be inventories to moraines inheritance for now we neglect boulder erosion and snow cover which are likely second order processes given a highly scattered data set we establish which model yields the better fit to the data and estimate the age of the moraine from the better model fit the process represented by the better fitting model is probably responsible for most of the scatter among the apparent ages our methods should help resolve controversies in exposure dating we reexamine the conclusions from two published studies based on our model fits

a multidisciplinary approach to understanding carbonate deposition under tectonically controlled hydrothermal circulation a case study from a recent travertine mound in the euganean hydrothermal system northern italy a multidisciplinary study was carried out on an upper pleistocene travertine mound montirone hill abano terme south of padova veneto italy with the aim of developing a comprehensive understanding of the processes interacting in structurally controlled thermal springs and the consequent deposition of thermal limestones the sedimentology geochemistry structural characteristics and hydrogeology of the mound which is associated with the euganean geothermal field and the related complex structural framework of the schio vicenza fault system were investigated a palaeo environmental model of the deposit has been reconstructed clarifying the connection between the travertine deposition and the regional structural setting calcium rich thermal waters rose from spring orifices estimated temperature from 54 c to 61 c based on geochemical calculations and produced a mound made of coalescent shield like bodies the dominant lime mudstone facies resulted from the accumulation of lime mud at the bottom of shallow crater like basins located on top of stacked cones soft sediment deformations affecting the lime mud sediment were most probably produced by the recurrent uprising of gas bubbles the overlying crystalline crusts were deposited on the flanks of the mound by waters overflowing from the vents with laminar flux a deep hydrothermal circuit with a long period of water rock interaction is supported by geochemical analyses furthermore a local extensional regime enhancing the migration of thermal fluids to the surface is inferred based on the results of the structural analysis carried out on the fault fracture mesh that affects the mound these results corroborate the well established relation among travertine deposits hydrothermal systems and fault systems and substantiate the structurally controlled conceptual model of the euganean hydrothermal system suggesting that both the thermal and the fault systems were active at least since 34 ka

early pleistocene river terraces of the gediz river turkey the role of faulting fracturing volcanism and travertines in their genesis abstract reconstructing and interpreting past hydrological system changes from the quaternary sediment landform record presents many challenges especially when trying to establish causality in such circumstances attempting to isolate individual drivers is perhaps unrealistic and thus inferences are made with respect to the combined influence of multiple controls and constraints in this paper we seek to interpret the landscape responses recorded in the sediment landform record of the early pleistocene gediz valley western turkey within the context of interacting geodynamic and hydrodynamic system changes our earlier work on the gediz sequence established the presence of a rich fluvial archive constrained by a comprehensive geochronology from overlying lava flows repeated damming of the gediz valley floor and consequent re routing of water flow testifies to a direct connection between fluvial activity and volcanism this volcanism has been linked to regional tectonic extension with regional uplift promoted as a major driver of the progressive river incision of the gediz river over the quaternary this incision has been punctuated by periods of deposition dictated by sediment and water budgets controlled principally by fluctuating climate and consequent vegetation change recently however the significance of more local fault movements and fracturing has been recognised and here we examine and attempt to quantify these geodynamics in greater detail in addition we examine and describe for the first time extensive associated travertine deposits isotopic analysis of these travertines confirms their thermogenic origin and directly links their creation to the faulting fracturing volcanism and the recycling of calcium rich groundwater the formation of mounds and sheets extend onto their contemporary valley floors thus directly connecting the fluvial and travertine archives and allowing linkage between surface and subsurface hydrological change by utilising both the fluvial and travertine archives a more complex picture of landscape evolution emerges the youngest terraces the gediz sequence demonstrates increasing complexity there is no reason to suggest this is unusual although climate and tectonics remain as key drivers the local landscape response is also conditioned by many additional factors while it is tempting to search for global patterns the big picture such reduced complexity may be over simplistic recognising complexity requires detailed observation and therefore more emphasis on the smaller picture which can only be obtained through extensive field observation

origins of elements building travertine and tufa new perspectives provided by isotopic and geochemical tracers fluid rock interaction represents a major process in the formation of calcitic or aragonitic travertine and tufa catt in most cases catt is associated to limestone dissolution somewhere along the hydrogeological pathway however a wide array of other substratum basalts rhyolites carbonatites ultramafics granites dolomites evaporites can act as potential source of elements involved in the formation of catt this study reports on the evaluation of potential geochemical tracers linking catt to their substratum and unravelling the origin of elements a large database was established from available literature data as well as new data acquired in the frame of this study for a set of modern to recent catt ligurian ophiolites italy the chaine des puys limagne graben and paris basin france reunion island indian ocean jebel oust tunisia four most reliable tracing methods are identified 1 13c and 18o cross plot allows distinguishing epigean min 13c 27 2 max 13c 0 9 mean 13c 12 3 for n 314 from hypogean systems min 13c 4 max 13c 11 7 mean 13c 2 87 for n 198 very low 13c values 4 associated to negative 13c values are specifically indicative of an ultramafic source rock 2 barium and strontium cross plot helps to discriminate different groups of source rocks amongst the hypogean catt i source rocks composed of mixed limestones evaporites and dolomites are characterised by low barium 400 ppm contents ii mafic and granitic source rocks are undifferentiated and display similar barium from 15 to 930 ppm and high strontium 200 ppm contents iii the carbonatite group is characterised by its exceptional high barium and strontium values in epigean catt a pure limestone source rock usually relates to very low barium and strontium contents 50 ppm 3 relatively high beryllium content 30 ppm in catt seems to indicate a pure granitoid source 4 high chromium concentrations 20 ppm are systematically documented in modern catt located on an ultramafic substratum the definition of diagnostic compositional fields for actively forming or recently formed catt is influenced by many factors including water composition water temperature dissolved gas composition and concentration biological activity position in the sedimentary body and early diagenesis in addition to substratum lithology however the results of this study illustrate that despite these many factors the combined use of ba sr be cr 13c and 18o may be valuable to discriminate the rock lithology prevailing in the hydrogeological or palaeo hydrogeological reservoir of catt

tectono stratigraphic evolution of the ne sw trending superimposed selendi basin implications for late cenozoic crustal extension in western anatolia turkey abstract selendi basin is located in the eastern part of western anatolia that is the easternmost part of the aegean extensional province in western anatolia crustal extension resulted in exhumation of the mid crustal units the menderes massif synchronously with volcano sedimentary basin formation the stratigraphic and tectonic features of the volcano sedimentary succession reflect the exhumation processes and the modes of extension we present new stratigraphical sedimentological structural and 40ar 39ar age data from the neogene volcano sedimentary fill of the ne sw trending selendi basin the data show that crustal extension in the region occurred in four distinct episodes and accommodated the exhumation of the menderes massif and the basin formation throughout the late cenozoic late oligocene to early miocene detachment faulting the simav detachment fault sdf is attributed to the first episode clastic sedimentation and bimodal volcanism of 20 0 17 5 ma the hacibekir group age was formed in the hanging wall of the sdf during the exhumation of northern menderes massif in the footwall during second episode the menderes collapse occurred and was manifest by formation of the gediz detachment fault gdf during the middle miocene activity on the gdf has resulted in the exhumation of the central menderes massif in the bozdag area during this period the hanging wall of the gdf was dissected by ne sw trending high angle oblique slip cross faults and accommodated clastic to lacustrine carbonate deposition and syn sedimentary bimodal volcanism of 16 15 ma the inay group the third episode is represented by formation of nw se trending sinistral and ne sw trending dextral strike to oblique slip faults and associated dip to oblique slip normal faults during the late miocene indicating that the area was deformed under a strike slip tectonic regime the faults localized alluvial sedimentation the kocakuz formation and basaltic volcanism of 7 8 ma the kabaklar basalt in the selendi basin the last episode commenced by the start of the plio quaternary this period is represented by the currently active n s extensional tectonic regime that resulted in the formation of e w trending high angle normal faults that controls the present day e w trending graben type basin formation e g gediz and simav grabens and the quaternary 1200 60 ka basaltic volcanism

the determination of fault movement history from the interaction of local drainage with volcanic episodes the kula volcanic province lies in an area of active normal faulting in western turkey in this study we show that the interaction of the basalts with the local drainage and in particular the gediz river can be used to determine the history of fault movements downstream the lava flows have been studied previously and some of them dated we use these results and combine them with new field observations of lavas that flowed into the river valley to measure the rate of down cutting of the river and hence the rate of uplift of the footwall block due to movement of the graben bounding fault we show that there has been in general an acceleration of fault movement with time during the last 2 ma this increased activity of the graben bounding fault is matched by an intensification of volcanic activity an inferred four fold increase in fault movement rate over the last 0 2 ma has been matched by a similar increase in volume of volcanic activity

ice streams in the laurentide ice sheet identification characteristics and comparison to modern ice sheets this paper presents a comprehensive review and synthesis of ice streams in the laurentide ice sheet lis based on a new mapping inventory that includes previously hypothesised ice streams and includes a concerted effort to search for others from across the entire ice sheet bed the inventory includes 117 ice streams which have been identified based on a variety of evidence including their bedform imprint large scale geomorphology topography till properties and ice rafted debris in ocean sediment records despite uncertainty in identifying ice streams in hard bedrock areas it is unlikely that any major ice streams have been missed during the last glacial maximum laurentide ice streams formed a drainage pattern that bears close resemblance to the present day velocity patterns in modern ice sheets large ice streams had extensive onset zones and were fed by multiple tributaries and where ice drained through regions of high relief the spacing of ice streams shows a degree of spatial self organisation which has hitherto not been recognised topography exerted a primary control on the location of ice streams but there were large areas along the western and southern margin of the ice sheet where the bed was composed of weaker sedimentary bedrock and where networks of ice streams switched direction repeatedly and probably over short time scales as the ice sheet retreated onto its low relief interior several ice streams show no correspondence with topography or underlying geology perhaps facilitated by localised build up of pressurised subglacial meltwater they differed from most other ice stream tracks in having much lower length to width ratios and have no modern analogues there have been very few attempts to date the initiation and cessation of ice streams but it is clear that ice streams switched on and off during deglaciation rather than maintaining the same trajectory as the ice margin retreated we provide a first order estimate of changes in ice stream activity during deglaciation and show that around 30 of the margin was drained by ice streams at the lgm similar to that for present day antarctic ice sheets but this decreases to 15 and 12 at 12 cal ka bp and 10 cal ka bp respectively the extent to which these changes in the ice stream drainage network represent a simple and predictable readjustment to a changing mass balance driven by climate or internal ice dynamical feedbacks unrelated to climate or both is largely unknown and represents a key area for future work to address

the kula volcanic field western turkey the development of a holocene alkali basalt province and the adjacent normal faulting graben the kula province of western turkey provides an excellent example of an alkali basalt province in an area of active rifting this paper establishes the relationship between the generation of the basalts and the extension of the region the wide shallow terrestrial basin formed by early extension was subsequently cut through by narrow fault bounded grabens the genesis of alkali basalt magmas began soon after the concentration of the extension into two grabens 2 ma the basalts in the form of some 80 small cinder cones and associated lava flows and fields have a total volume of 2 3 km 3 this small volume reflects the small amount of extension in the region

a pulsed extension model for the neogene recent e w trending alasehir graben and the ne sw trending selendi and gordes basins western turkey abstract we have developed a significant body of new field based evidence relating to the history of crustal extension in western turkey we establish that two of the ne sw trending basins in this region the gordes and selendi basins whose sedimentary successions begin in the early miocene are unlikely to relate to late stage alpine compressional orogeny or to e w extension of tibetan type grabens as previously suggested we argue instead that these basins are the result of earlier late oligocene low angle normal faulting that created approximately n s scoop shaped depressions in which clastic to lacustine and later tuffaceous sediments accumulated during early mid miocene time separated by elongate structural highs these basins were later cut by e w trending plio quaternary normal faults that post date accumulation of the neogene deposits in addition we interpret the alasehir gediz graben in terms of two phases of extension an early phase lasting from the early miocene to the late miocene and a young plio quaternary phase that is still active taking into account our inferred earlier phase of regional extension we thus propose a new three phase pulsed extension model for western turkey we relate the first two phases to roll back of the south aegean subduction zone and the third phase to the westward tectonic escape of anatolia

pliocene and quaternary regional uplift in western turkey the gediz river terrace staircase and the volcanism at kula abstract along the upper reaches of the gediz river in western turkey in the eastern part of the aegean extensional province the land surface has uplifted by 400 m since the middle pliocene this uplift is revealed by progressive gorge incision and its rate can be established because river terraces are capped by basalt flows that have been k ar and ar ar dated at present the local uplift rate is 0 2 mm a 1 uplift at this rate began around the start of the middle pleistocene following a span of time when the uplift was much slower this was itself preceded by an earlier uplift phase apparently in the late late pliocene and early early pleistocene when the uplift rate was comparable to the present the resulting regional uplift history resembles what is observed in other regions and is analogously interpreted as the isostatic response to changing rates of surface processes linked to global environmental change we suggest that this present phase of surface uplift amounting so far to 150 m is being caused by the nonsteady state thermal and isostatic response of the crust to erosion following an increase in erosion rates in the late early pleistocene most likely as a result of the first large northern hemisphere glaciation during oxygen isotope stage 22 at 870 ka we suggest that the earlier uplift phase responsible for the initial 250 m of uplift resulted from a similar increase in erosion rates caused by the deterioration in local climate at 3 1 ma this uplift thus has no direct relationship to the crustal extension occurring in western turkey the rate and sense of which are thought not to have changed significantly on this time scale our results thus suggest that the present often deeply incised landscape of western turkey has largely developed from the middle pleistocene onwards for reasons not directly related to the active normal faulting that is also occurring the local isostatic consequences of this active faulting are instead superimposed onto this background of regional surface uplift modelling of this surface uplift indicates that the effective viscosity of the lower continental crust beneath this part of turkey is of the order of 1019 pa s similar to a recent estimate for beneath central greece the lower uplift rates observed in western turkey compared with central greece result from the longer typical distances of fluvial sediment transport which cause weaker coupling by lower crustal flow between offshore depocentres and eroding onshore regions that provide the sediment source

river terraces as a response to climatic forcing formation processes sedimentary characteristics and sites for human occupation abstract climate impact on the fluvial processes led to morphological and sedimentological differentiation of a terrace this diversity in the fluvial environment determined how people could adapt to the river although the climatic impact on development and initiation of river terraces seems to be well accepted a number of pertinent questions disturb this simplicity for instance the exact terrace development within a climate cycle is still under debate different kinds of terraces and their sedimentary successions may originate either from aggradation incision or lateral migration is there a typical sedimentary succession below terraces what is the genetic origin of each sedimentary layer what are the relative ages of those layers and erosion phases within a climate driven erosion aggradation cycle the variability in staircase preservation in relation to climatic cyclicity is analysed in three scenarios specific scenarios depend essentially on the preservation of the fluvial deposits dating from the warm periods finally a preliminary inventory is presented of the most favourable sites for human occupation in fluvial valleys as derived from a random selection of archaeological findings generally human occupation in that morphological position seems to be linked with at least temporarily dry conditions climatic conditions do not seem to play the major role the termination of a settlement may have been due to increased risks of flooding apart from other than natural fluvio environmental reasons

fluvial archives a valuable record of vertical crustal deformation abstract the study of drainage network response to uplift is important not only for understanding river system dynamics and associated channel properties and fluvial landforms but also for identifying the nature of crustal deformation and its history in recent decades geomorphic analysis of rivers has proved powerful in elucidating the tectonic evolution of actively uplifting and eroding orogens here we review the main recent developments that have improved and expanded qualitative and quantitative information about vertical tectonic motions the effects of horizontal deformation are not addressed channel long profiles have received considerable attention in the literature and we briefly introduce basic aspects of the behaviour of bedrock rivers from field and numerical modelling perspectives before describing the various metrics that have been proposed to identify the information on crustal deformation contained within their steady state characteristics then we review the literature dealing with the transient response of rivers to tectonic perturbation through the production of knickpoints propagating through the drainage network inverse modelling of river profiles for uplift in time and space is also shown to be very effective in reconstructing regional tectonic histories finally we present a synthetic morphometric approach for deducing the tectonic record of fluvial landscapes as well as the erosional imprint of tectonic forcing sedimentary deposits such as fluvial terrace staircases are also considered as a classical component of tectonic geomorphology we show that these studies have recently benefited from rapid advances in dating techniques allowing more reliable reconstruction of incision histories and estimation of incision rates the combination of progress in the understanding of transient river profiles and larger more rigorous data sets of terrace ages has led to improved understanding of river erosion and the implications for terrace profile correlation i e extrapolation of local data to entire profiles finally planform changes in fluvial systems are considered at the channel scale in alluvial rivers and regional level in terms of drainage reorganisation examples are given of how numerical modelling can efficiently combine with topographic data to shed new light on the dis equilibrium state of drainage systems across regional drainage divides

the earliest securely dated hominin artefact in anatolia anatolia lies at the gateway from asia into europe and has frequently been favoured as a route for early pleistocene hominin dispersal although early hominins are known to have occupied turkey with numerous finds of lower palaeolithic artefacts documented the chronology of their dispersal has little reliable stratigraphical or geochronological constraint sites are rare and the region s hominin history remains poorly understood as a result here we present a palaeolithic artefact a hard hammer flake from fluvial sediments associated with the early pleistocene gediz river of western turkey this previously documented buried river terrace sequence provides a clear stratigraphical context for the find and affords opportunities for independent age estimation using the numerous basaltic lava flows that emanated from nearby volcanic necks and aperiodically encroached onto the contemporary valley floors new 40 ar 39 ar age estimates from these flows are reported here which together with palaeomagnetic measurements allow a tightly constrained chronology for the artefact bearing sediments to be established these results suggest that hominin occupation of the valley occurred within a time period spanning 1 24 ma to 1 17 ma making this the earliest securely dated record of hominin occupation in

reconciling records of ice streaming and ice margin retreat to produce a palaeogeographic reconstruction of the deglaciation of the laurentide ice sheet abstract this paper reconstructs the deglaciation of the laurentide ice sheet lis including the innuitian ice sheet from the last glacial maximum lgm with a particular focus on the spatial and temporal variations in ice streaming and the associated changes in flow patterns and ice divides we build on a recent inventory of laurentide ice streams and use an existing ice margin chronology to produce the first detailed transient reconstruction of the ice stream drainage network in the lis which we depict in a series of palaeogeographic maps results show that the drainage network at the lgm was similar to modern day antarctica the majority of the ice streams were marine terminating and topographically controlled and many of these continued to function late into the deglaciation until the ice sheet lost its marine margin ice streams with a terrestrial ice margin in the west and south were more transient and ice flow directions changed with the build up peak phase and collapse of the cordilleran laurentide ice saddle the south eastern marine margin in atlantic canada started to retreat relatively early and some of the ice streams in this region switched off at or shortly after the lgm in contrast the ice streams draining towards the north western and north eastern marine margins in the beaufort sea and in baffin bay appear to have remained stable throughout most of the late glacial and some of them continued to function until after the younger dryas yd the yd influenced the dynamics of the deglaciation but there remains uncertainty about the response of the ice sheet in several sectors we tentatively ascribe the switching on of some major ice streams during this period e g m clintock channel ice stream at the north west margin but for other large ice streams whose timing partially overlaps with the yd the drivers are less clear and ice dynamical processes rather than effects of climate and surface mass balance are viewed as more likely drivers retreat rates markedly increased after the yd and the ice sheet became limited to the canadian shield this hard bed substrate brought a change in the character of ice streaming which became less frequent but generated much broader terrestrial ice streams the final collapse of the ice sheet saw a series of small ephemeral ice streams that resulted from the rapidly changing ice sheet geometry in and around hudson bay our reconstruction indicates that the lis underwent a transition from a topographically controlled ice drainage network at the lgm to an ice drainage network characterised by less frequent broad ice streams during the later stages of deglaciation these deglacial ice streams are mostly interpreted as a reaction to localised ice dynamical forcing flotation and calving of the ice front in glacial lakes and transgressing sea basal de coupling due to large amount of meltwater reaching the bed debuttressing due to rapid changes in ice sheet geometry rather than as conveyors of excess mass from the accumulation area of the ice sheet at an ice sheet scale the ice stream drainage network became less widespread and less efficient with the decreasing size of the deglaciating ice sheet the final elimination of which was mostly driven by surface melt

late glacial fluctuations of the laurentide ice sheet in the white mountains of maine and new hampshire u s a abstract prominent moraines deposited by the laurentide ice sheet in northern new england document readvances or stillstands of the ice margin during overall deglaciation however until now the paucity of direct chronologies over much of the region has precluded meaningful assessment of the mechanisms that drove these events or of the complex relationships between ice sheet dynamics and climate as a step towards addressing this problem we present a cosmogenic 10be surface exposure chronology from the androscoggin moraine complex located in the white mountains of western maine and northern new hampshire as well as four recalculated ages from the nearby littleton bethlehem moraine seven internally consistent 10be ages from the androscoggin terminal moraines indicate that advance culminated 13 2 0 8 ka in close agreement with the mean age of the neighboring littleton bethlehem complex together these two datasets indicate stabilization or advance of the ice sheet margin in northern new england at 14 13 ka during the allerod greenland interstadial i

tectonic and lithological controls on fluvial landscape development in central eastern portugal insights from long profile tributary stream analyses abstract this study examines the long profiles of tributaries of the tagus and zezere rivers in portugal west iberia in order to provide new insights into patterns timing and controls on drainage development during the quaternary incision stage the studied streams are incised into a relict culminant fluvial surface abandoned at the beginning of the incision stage the streams flow through a landscape with bedrock variations in lithology mainly granites and metasediments and faulted blocks with distinct uplift rates the long profiles of the analyzed streams record an older transitory knickpoint knickzone separating 1 an upstream relict graded profile with lower steepness and higher concavity that reflects a long period of quasi equilibrium conditions reached after the beginning of the incision stage and 2 a downstream rejuvenated long profile with steeper gradient and lower concavity particularly for the final reach which is often convex the rejuvenated reaches testify to the upstream propagation of several incision waves interpreted as the response of each stream to increasing crustal uplift and prolonged periods of base level lowering by the trunk drainages coeval with low sea level conditions the morphological configurations of the long profiles enabled spatial and relative temporal patterns of incisions to be quantified the incision values of streams flowing on the portuguese central range pcr ca 380 150 m are variable but generally higher than the incision values of streams flowing on the adjacent south portugal planation surface spps ca 220 110 m corroborating differential uplift of the pcr relative to the spps owing to the fact that the relict graded profiles can be correlated with the tagus river t1 terrace 1 1 0 9 my present in the study area incision rates can be estimated 1 for the streams located in the pcr 0 38 0 15 m ky and 2 for the streams flowing on the spps 0 22 0 12 m ky the differential uplift inferred in the study area supports the neotectonic activity of the bordering faults as proposed in previous studies based upon other geological evidence

cyclic aggradation and downcutting fluvial response to volcanic activity and calibration of soil carbonate stages in the western grand canyon arizona abstract in the western grand canyon fluvial terraces and pediment surfaces both associated with a pleistocene basalt flow document quaternary aggradation and downcutting by the colorado river illuminate the river s response to overload and the end of overload and allow calibration of soil carbonate stages and determination of downcutting rates four downcutting aggradation cycles are present each begins with erosion of older deposits to form a new river channel in which a characteristic suite of deposits is laid down the current cycle i started 700 yr b p the oldest iv includes the 603 000 8000 to 524 000 7000 yr black ledge basalt flow emplaced when the river channel was 30 m higher than it is now the flow is overlain by basalt cobble gravel and basalt sand soils reach the stage v level of carbonate development calibrated ages for soil stages are stage v 525 000 yr stage iv

reconstructing early pleistocene 1 3 ma terrestrial environmental change in western anatolia did it drive fluvial terrace formation a terrestrial environmental reconstruction of an early pleistocene landscape from western anatolia is presented the basis of this reconstruction is a sedimentary stack comprising fluvial and colluvial slope deposits contained within this stack is a sequence comprising two massive laminar calcretes alternating with three reddish palaeosols this evolutionary sequence is situated on top of a fluvial terrace staircase capped by a 1 3 ma 40ar 39ar plateau age lava flow the micro morphological properties of the observed calcretes and reddish palaeosols combined with the stable oxygen and carbon isotopic composition of the carbonates suggest the alternation of three stable relatively warm humid vegetation rich and two stable relatively arid cool bare surface cycles in addition there is also ample evidence for landscape instability in between these phases causing local soil truncation and slope instability in an open grassland shrub environment these landscape instability phases match well with known fluvial incisional phases of the gediz during this period this suggests that climate forced landscape environmental dynamics were of sufficient magnitude to drive fluvial terrace formation of the early pleistocene gediz

fluvial response to holocene volcanic damming and breaching in the gediz and geren rivers western turkey this study discusses the complex late holocene evolution of the gediz river north of kula western turkey when a basaltic lava flow dammed and filled this river valley age control was obtained using established and novel feldspar luminescence techniques on fluvial sands below and on top of the flow this dating constrained the age of the lava flow to 3 0 2 6 ka two damming locations caused by the lava flow have been investigated the upstream dam caused lake formation and siltation of the upstream gediz the downstream dam blocked both the gediz and a tributary river the geren the associated lake was not silted up because the upstream dam already trapped all the gediz sediments backfillings of the downstream lake are found 1 5 km upstream into the geren valley the downstream dam breached first after which the upstream dam breached creating an outburst flood that imbricated boulders of 10 m3 size and created an epigenetic gorge the gediz has lowered its floodplain level at least 15 m since the time of damming triggering landslides some of which are active until present the lower reach of the geren has experienced fast base level lowering and changed regime from meandering to a straight channel complex response to base level change is still ongoing in the geren and gediz catchments these findings are summarized in a diagram conceptualizing lava damming and breaching events this study demonstrates that one lava flow filling a valley floor can block a river at several locations leading to different but interrelated fluvial responses of the same river system to the same lava flow

stratigraphy and correlation of the glacial deposits of the des moines and james lobes and adjacent areas in north dakota south dakota minnesota and iowa the glacial deposits of the des moines and james lobes record the extension of late wisconsin laurentide ice from canada into minnesota and iowa and into north dakota and south dakota respectively fig 1 chart 1 d e in this review we also discuss wisconsin age deposits of adjacent parts of north dakota and pre wisconsin deposits in north dakota south dakota and southwestern minnesota chart 1 b c e

tectono stratigraphy of the neogene basins in western turkey implications for tectonic evolution of the aegean extended region abstract the western part of the aegean region includes several neogene basins containing volcano sedimentary successions the neogene basins located along the northern menderes extensional metamorphic complex memc were developed during the miocene as supra detachment basins they contain two distinct volcano sedimentary successions separated by a regional unconformity the basins located to the west of the memc were developed as strike slip basins and contain volcanic and sedimentary units getting younger from ne to sw with no remarkable unconformity available paleomagnetic studies in the aegean region suggest to us that the basins to the west of the memc were developed in response to southward clockwise rotational roll back of the aegean subduction zone the eastern margin of this rotational deformation is characterized on the surface by a large strike slip zone which is known as izmir balikesir transfer zone ibtz the sedimentary successions in the basins along the northern memc do not show southward younging and are interpreted to be developed in response to exhumation of the memc during the pliocene to quaternary e w trending grabens such as the gediz alasehir buyuk and kucuk menderes grabens were developed in response to tectonic escape accompanying the slab roll back process these grabens truncate the memc basins during this time strike slip deformation and associated sedimentation continued along the ibtz

terrace formation and river valley development along the lower taohe river in central china abstract a flight of nine river terraces has been well developed and preserved along the course of the lower taohe river based on optically stimulated luminescence osl electron spin resonance esr paleomagnetic and loess paleosol stratigraphic analyses we found that the accumulation ages of the gravel layers of terraces t9 t1 correspond to the loess layers l13 l9 l8 l6 l5 l4 l3 l2 l1 4 and l1 1 respectively the chronologic results indicate that the formation and development of the modern river valley in this area occurred between 1 4 and 1 14 ma the topographic fluctuation caused by the kunhuang movement appears to have been the main reason for the reorganization of the river system and valley development in the area in the context of this tectonic uplift fluvial processes were coupled with the regional climate on a geomorphic equilibrium scale i e over a glacial interglacial cycle that is river aggradation appears principally to have occurred during glacial periods while a graded state existed during interglacial periods in addition rapid river downcutting in response to climate change occurred during the transition periods from glacial to interglacial climates

late cenozoic tectono sedimentary development of the selendi and usak gure basins a contribution to the discussion on the development of east west and north trending basins in western turkey

analysis of multiple cosmogenic nuclides constrains laurentide ice sheet history and process on mt mansfield vermont s highest peak abstract constraining glacial history and process on mt mansfield the highest peak in vermont 1339 m a s l provides insight into how the laurentide ice sheet shaped the underlying landscape when latest pleistocene ice retreated and how upland and lowland glacial histories relate here we quantify in situ cosmogenic 10be in 20 bedrock and boulder surfaces as well as in situ cosmogenic 14c in three of those surfaces to assess subglacial erosion and exposure history isotopic concentrations indicate that mt mansfield s lower elevations 400 1200 m a s l were deeply eroded by at least several meters during the last glaciation and then deglaciated rapidly 10be ages across this elevation span are indistinguishable and average 13 9 0 6 ka n 15 suggesting that 800 m of ice thinning occurred within at most about a millennium conversely the higher elevations 1200 m a s l preserve a more complex geomorphic history mt mansfield s summit surfaces contain 10be from previous periods of exposure indicating that the mountaintop landscapes were likely preserved beneath cold based weakly erosive glacial ice exposure ages from the shorter lived isotope 14c are younger 9 7 and 11 7 ka suggesting that mt mansfield s summit was covered until the early holocene perhaps by snowfields ice carapaces and or till our findings in context of previous work suggest that thinning laurentide ice flowed through the valleys for at most hundreds of years following deglaciation of the uplands but that the summit remained shielded by ice or sediment for millennia after the valleys became ice free

controls on dryland mountain landscape development along the nw saharan desert margin insights from quaternary river terrace sequences dades river south central high atlas morocco abstract this study documents river terraces from upstream reaches of the dades river a major fluvial system draining the south central high atlas mountains terraces occur as straths with bedrock bases positioned at 10 m altitudinal intervals up to 40 m t1 t5 above the valley floor becoming less common between 50 and 140 m the rock strength stratigraphy and structure of the mountain belt influences terrace distribution terraces are absent in river gorges of structurally thickened limestone whilst well developed laterally continuous terraces t1 t4 form along wide valleys occupying syncline structures dominated by weaker interbedded limestone mudstone terrace staircases develop in confined canyons associated with weaker lithologies and influence from structural dip and stratigraphic configuration terraces comprise a bedrock erosion surface overlain by fluvial conglomerates rare overbank sands and colluvium this sequence with some osl irsl age control suggests terrace formation over a 100 ka climate cycle with valley floor aggradation during full glacials and incision during glacial interglacial transitions this integrates with other archives e g lakes glaciers dunes appearing typical of landscape development along the nw saharan margin south of the high atlas and similar to patterns in the western southern mediterranean the 100 ka climate cycle relationship suggests that the terrace sequence documents late middle pleistocene landscape development consistent altitudinal spacing of terraces and their distribution throughout the orogen suggests sustained base level lowering linked to uplift exhumation of the high atlas low incision rates 1 and general absence of terrace deformation suggests dominance of isostatically driven base level lowering with relief generation being early pleistocene or older

modelling the impact of regional uplift and local tectonics on fluvial terrace preservation abstract a terrace formation model terrace combined with a longitudinal river profile model fluver was used to simulate fluvial terrace formation and preservation in the northwest iberian lower mino river basin under the influence of three tectonic conditions namely regional vertical uplift local basin subsidence and localised differential uplift the simulation results were compared against mapped terrace altitudes and deposit thicknesses the best results were achieved by combining all three tectonic factors indicating that specific terrace formation is a complex interplay of regional and local tectonics the best fit regional uplift rate of 0 10 m ka 1 over the past 600 ka is higher than the 0 08 m ka 1 previously estimated for a section farther to the west which can be attributed to an increase in tectonic uplift from the nw iberian atlantic margin toward the east local relative subsidence causes sediment accumulation in the local basin and less sedimentation in the fluvial terraces on the surrounding uplifting blocks different uplift rates on both sides of the valley caused preservation of unpaired terraces which are fill terraces on one side of the valley and strath terraces on the other side usually the formation of fill or strath terraces is considered to be only climate dependent our results indicate that local tectonics can be important in the terrace formation and preservation this suggests that terrace correlations in other river systems based on deposit thicknesses only might be over simplified

spatial and temporal variations in river terrace formation preservation and morphology in the lower meuse valley the netherlands the lower meuse valley crosses the roer valley rift system and provides an outstanding example of well preserved late glacial and holocene river terraces the formation preservation and morphology of these terraces vary due to reach specific conditions a phenomenon that has been underappreciated in past studies a detailed palaeogeographic reconstruction of the terrace series over the full length of the lower meuse valley has been performed this reconstruction provides improved insight into successive morphological responses to combined climatic and tectonic external forcing as expressed and preserved in different ways along the river new field data and data obtained from past studies were integrated using a digital mapping method in gis results show that late glacial river terraces with diverse fluvial styles are best preserved in the lower meuse valley downstream sub reaches traversing the venlo block and peel block while holocene terrace remnants are well developed and preserved in the upstream sub reaches traversing the campine block and roer valley graben this reach to reach spatial variance in river terrace preservation and morphology can be ascribed to tectonically driven variations in river gradient and subsurface lithology and to river driven throughput of sediment supply

cosmogenic exposure age evidence for rapid laurentide deglaciation of the katahdin area west central maine usa 16 to 15 ka abstract katahdin the highest peak in maine and part of the second highest mountain range in new england provides an opportunity to assess the timing and style of continental ice sheet surface lowering during deglaciation we collected 14 samples from boulders on the adjacent basin ponds moraine from bedrock and boulders on the upper part of the mountain and from boulders in the surrounding area to estimate the age at which they were exposed by deglaciation of the laurentide ice sheet measurements of in situ produced 10be which are consistent with measurements of 26al indicate that the katahdin edifice became exposed from under ice by 15 3 2 1 ka n 6 an age indistinguishable from the adjacent basin ponds moraine 16 1 1 2 ka n 5 a boulder in the lowlands several km south of the moraine dates to 14 5 0 8 ka and a boulder deposited at pineo ridge about 170 km se of katahdin dates to 17 5 1 1 ka these data show that samples collected over an elevation range of 1 6 km and a distance of 170 km all have exposure ages that are indistinguishable within uncertainties together these data suggest that the laurentide ice sheet surface dropped rapidly and the ice sheet margin retreated quickly across maine between about 16 and 15 ka perhaps influenced by calving of the marine based ice sheet in the st lawrence lowlands to the north and the penobscot basin to the south

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