neogene ignimbrites of the nevsehir plateau central turkey stratigraphy distribution and source constraints abstract in anatolia turkey extensive calc alkaline volcanism has developed along discontinuous provinces from neogene to quaternary times as a consequence of plate convergence and continental collision in the nevsehir plateau which is located in the central anatolian volcanic province volcanism consists of numerous monogenetic centres several large stratovolcanoes and an extensive mainly neogene rhyolitic ignimbrite field vent and caldera locations for the neogene ignimbrites were not well known based on previous studies in the neogene ignimbrite sequence of the nevsehir plateau we have identified an old group of ignimbrites kavak ignimbrites followed by five major ignimbrite units zelve sarimaden tepe cemilkoy gordeles kizilkaya and two smaller less extensive ones tahar sofular other ignimbrite units at the margin of the plateau occur as outliers of larger ignimbrites whose main distributions are beyond the plateau excellent exposure and physical continuity of the units over large areas have allowed establishment of the stratigraphic succession of the ignimbrites as from bottom to top kavak zelve sarimaden tepe cemilkoy tahar gordeles sofular kizilkaya our stratigraphic scheme refines previous ones by the identification of the zelve ignimbrite and the correlation of the previously defined akkoy ignimbrite with the sarimaden tepe ignimbrite correlations of distant ignimbrite remnants have been achieved by using a combination a field criteria 1 sedimentological characterisitics 2 phenocryst assemblage 3 pumice vesiculation texture 4 presence and characteristics of associated plinian fallout deposits and 5 lithic types the correlations significantly enlarge the estimates of the original extent and volume of most ignimbrites volumes range between 80 km 3 and 300 km 3 for the major ignimbrites corresponding to 2500 10 000 km 3 in areal extent the major ignimbrites of the nevsehir plateau have an inferred source area in the derinkuyu tectonic basin which extends mainly between nevsehir and the melendiz dag volcanic complex the kavak ignimbrites and the zelve ignimbrite have inferred sources located between nevsehir and derinkuyu coincident with a negative gravity anomaly the younger ignimbrites sarimaden tepe cemilkoy gordeles kizilkaya have inferred sources clustered to the south between the erdas dag and the melendiz dag volcanic complex we found evidence of collapse structures on the northern and southern flanks of the erdas dag volcanic massif and of a large updoming structure in the sahinkalesi tepe massif the present day derinkuyu tectonic basin is mostly covered with quaternary sediments and volcanics the fault system which bounds the basin to the east provides evidence that the ignimbrite volcanism and inferred caldera formation took place in a locally extensional environment while the basin was already subsiding drilling and geophysical prospecting are necessary to decipher in detail the presently unknown internal structure of the basin and the inferred probably coalesced or nested calderas within it

stratigraphy and age of the cappadocia ignimbrites turkey reconciling field constraints with paleontologic radiochronologic geochemical and paleomagnetic data the stratigraphy and age of the neogene cappadocia ignimbrites central turkey have been inferred in previous studies from fieldwork and k ar age determinations the resulting stratigraphic schemes however differed from each other suggesting that further studies were required to produce a reliable succession in this paper we examine the chronostratigraphy of mammalian remains recovered in the continental sediments interbedded with the cappadocia ignimbrites using recent advances in mammalian chronostratigraphy we evaluate selected taxa and faunal associations to place new and independent constraints on the ignimbrite ages the biostratigraphically bracketed ages concur with some published radiometric dates but they disagree with others principally at localities where major stratigraphic discrepancies have arisen in the literature in order to reconcile these apparent inconsistencies we combine at selected sites our field observations with the biostratigraphic and radiometric age limits and we compare these with the available geochemical and magnetic data this allows us to present revised age estimates and a revised stratigraphy which includes the correlation of the local sofular deposits with the large volume gordeles ignimbrite the issues faced in this study apply to other ignimbrite provinces in the world for instance ignimbrite eruption frequency in cappadocia is higher than the resolution of many published k ar ages furthermore different k ar ages have led to the description of individual and distinct ignimbrites that fieldwork and geochemical data allow to merge into a single ignimbrite argon loss from pumice samples leading to radiometric rejuvenation provides a likely explanation for most stratigraphic discrepancies cappadocia is the only documented ignimbrite field in which the chronostratigraphy of vertebrate remains provides better constraints on some ignimbrite ages than scattered k ar dates we further argue that k ar dates from the cappadocia area are too imprecise to establish a reliable magnetostratigraphic scheme for the ignimbrite succession with the exception of the not vert similar2 8 ma valibaba tepe ignimbrite

a miocene phreatoplinian eruption in the north eastern pannonian basin hungary the jato member abstract a middle miocene 8 m thick pyroclastic succession reported from the bukk foreland volcanic area bfva in northern hungary central europe specified here as the jato member was produced by silicic phreatomagmatism phreatoplinian sensu lato two well preserved outcrops 8 km apart and inferred to be within 10 50 km from source represent the discontinuously exposed layered paleosol bounded phreatomagmatic jato member they show an identical phenocrystal assemblage of feldspar biotite and amphibole without weathered zones or signs of erosion that suggest deposition in one eruption phase lasting hours to months the succession contains three subunits 1 subunit a 1 8 m thick a series of well sorted fine to coarse ash or lapilli tuff layers with constant thickness 2 subunit b 2 1 m thick a series of normal graded layers with an upper fine grained zone containing abundant ash aggregates with a coarser grained core and distinctively finer grained outer rim 3 subunit c 4 5 m thick a massive poorly to well sorted coarse ash with gas escape structures and ash aggregates at its base the upward change of these lithofacies implies an initially sustained dry fallout dominated deposition of ash and pumice lapilli resulting in subunit a subsequently multiple wet and dilute pyroclastic density currents pdcs dispersed subunits b and c the general abundance of pdc related ash aggregates in the middle upper part of the succession particularly in subunit b and the transformation of a fall dominated to a collapsing depositional regime producing wet dilute pdcs imply the increasing influence of water during the eruption phreatoplinian sensu lato the presence of water is related to an epicontinental sea during middle to late miocene in the carpatho pannonian region the transition from an initial dry magmatic phase generated fallout activity followed by the emplacement of wet pdcs rich in ash aggregates when external water infiltrated from a surrounding lake or sea water entered the vent

core and intact polar glycerol dialkyl glycerol tetraethers gdgts in sand pond warwick rhode island usa insights into the origin of lacustrine gdgts branched and isoprenoidal glycerol dialkyl glycerol tetraethers gdgts are abundant in lake sediments and have potential use for determining past changes in climate and limnology however emerging evidence suggests that both classes of gdgts can be associated with both allochthonous soil organic matter and in situ production potentially complicating interpretation of these compounds in lacustrine sedimentary environments here we investigate the dual source issue surrounding lacustrine gdgts with an emphasis on the branched gdgts by studying both core and intact polar gdgts within a pond and its watershed in warwick ri significant differences in both absolute concentrations of branched gdgts and the percent of branched gdgts present as ipls between the soils and shallow lake sediments suggests in situ production of these compounds within the lake environment principal components analysis of gdgt lipid concentrations and environmental parameters in sand pond sediments and soils highlights two prominent trends in the data one related to the absolute concentrations of type i branched gdgts brgdgt i ib ic and the majority of the isoprenoidal gdgts and another related to the concentration of the more methylated type iii branched gdgts brgdgt iii iiib iiic and isoprenoidal gdgt 0 the latter trend exhibits a subsurface maximum in the sediment column potentially indicating in situ production of more highly methylated branched gdgts and gdgt 0 within the lacustrine sediment column trends in the distributions of branched gdgts as reflected by the mbt and cbt indices imply mixing of two distinct sources of branched gdgts soil derived and in situ or alternatively two or more different microbial producers both possibilities present a challenge to the application of brgdgt based paleoenvironmental proxies in lakes this study highlights the importance of determining the sources of gdgts to the lacustrine environment prior to paleoenvironmental application

palynostratigraphy and vegetation characteristics of neogene continental deposits interbedded with the cappadocia ignimbrites central anatolia turkey a palynological analysis of the late miocene and early pliocene successions of the cappadocian volcanic province central anatolia turkey has been carried out with the aim of reconstructing the palaeovegetation and palaeoclimatic conditions the samples are collected from outcrop sections from three different localities a akdag b bayramhacili and g guzeloz the pollen spectra reveals the existence of a steppe vegetation dominated by amaranthaceae chenopodiaceae and artemisia typical of present day arid and semi arid continental areas i e middle east and asteraceae asteroideae in the a section late miocene developed in arid climatic conditions the flora of the g early pliocene and lower part of the b late miocene sections reflects steppes on which asteraceae asteroideae was dominant this flora also indicates arid conditions the development of trees in the upper part of the b section was possibly related to local paleoenvironmental conditions rather than a climatic change this study provides the first palynological data to reveal the presence of an amaranthaceae chenopodiaceae and artemisia steppe already during the late miocene in turkey

weak compositional zonation in a silicic magmatic system incesu ignimbrite central anatolian volcanic province kayseri turkey abstract the central anatolian volcanic province cavp one of four major volcanic provinces in turkey plays a significant role in the interpretation of the tectonic evolution of central anatolia the cavp developed within a complex collisional system involving the african arabian and eurasian plates during the miocene the volcanism exhibits complicated variations in mineralogical petrological and geochemical compositions resulting from post collisional lithospheric dynamics the incesu ignimbrite has 5 20 m thick and covers an area of 7800 km2 it is composed of three stratigraphic levels the lower level ll shows blackish brown and glassy welded structure the middle level ml is a well welded reddish pink in color and has large amounts of fiamme the upper level ul is grayish pink weakly welded and has rock fragments of different compositions the incesu ignimbrite is composed of plagioclase oligoclase andesine pyroxene augite clinoenstatite opaque minerals and low amount of amphibole biotite and quartz eutaxitic texture is dominant in ml and ll samples these levels are more strongly and contain more flattened pumice fragments and volcanic glass shards than in the ul a sharp color contrast defines the contact between ll and ml major trace and rare earth element of the incesu ignimbrite characterized by their rhyolite rhyodacite dacite composition medium high k calcalkaline and peraluminous nature show fractional crystallization primarily controlled by plagioclase clinopyroxene magnetite ilmenite and titanomagnetite sr and nd isotopic ratios of incesu ignimbrite display isotopic variations between the ignimbrite levels they exhibit a limited range in 87sr 86sr 0 7043 0 7049 and 143nd 144nd 0 512716 0 512760 the sr nd isotopic ratio of incesu ignimbrite reveals an age of 3 ma the ignimbrite evolved through fractional crystallization and crystal contamination of the parent magma derived from ocean island basalt oib like magma this suggestion is supported by the afc modeling based on the trace elements and sr isotope data variation of several major oxide concentrations fe2o3 tio2 cao and k2o trace element concetrations v sr cs and rb and trace element ratios ba rb sr k sr k nb rb sr rb y and rb nb versus sio2 concentration show the magma chamber that generated the incesu ignimbrite was compositionally zoned all geochemical and sr nd isotpic datas can be interepreted to be the result of a subduction related source

a novel proxy for terrestrial organic matter in sediments based on branched and isoprenoid tetraether lipids we propose a novel tracer for terrestrial organic carbon in sediments based on the analysis of tetraether lipids using high performance liquid chromatography mass spectrometry hplc ms analysis of terrestrial soil and peats shows that branched tetraether lipids are predominant in terrestrial environments in contrast to crenarchaeol the characteristic membrane lipid of non thermophilic crenarchaeota which is especially abundant in the marine and lacustrine environment based on these findings an index was developed the so called branched and isoprenoid tetraether bit index based on the relative abundance of terrestrially derived tetraether lipids versus crenarchaeol this bit index was applied to surface sediments from the angola basin where it was shown to trace the outflow of the congo river furthermore analyses of particulate organic matter from the north sea showed relatively higher bit indices in water column particulate organic matter near large river inputs a survey of globally distributed marine and lacustrine surface sediments shows that the bit index in these environments correlates with the relative fluvial input of terrestrial organic material making this index generally applicable the new proxy allows the rapid assessment of the fluvial input of terrestrial organic material in immature sediments up to 100 ma old

characterizing the depositional settings for sedimentary organic matter distributions in the lower yangtze river east china sea shelf system grain size distributions total organic carbon toc and total nitrogen tn concentrations and toc tn ratios c n were analysed for surface sediments from the lower yangtze river east china sea ecs shelf system hierarchical cluster analysis of grain size parameters mode mean sorting skewness and kurtosis has been employed to characterize grain size compositions the results suggest there are five grain size compositional types type i v that fingerprint distinct depositional conditions in areas with high sedimentation rates hydrological sorting preferentially enriches the fraction coarser than 6 4o 12 m in shallow seafloor sediments water depth 30 m and thus forms grain size compositional type i shallow and type ii deep in the open shelf where modern sediment supply is very limited grain size types iii v are identified according to different winnowing intensity overall toc contents significantly correlate with mud proportions suggesting muddy sediments are the primary control on om accumulation however de association of terrestrial om from fine sediments in the estuary and the occurrence of presumably relict om in the open shelf exert additional controls on om dispersal and carbon cycling in the ecs by considering geography oceanography sediment source and the relation between sedimentation conditions and sedimentary om distributions we define six depositional settings the lower river the estuary the coast the offshore upwelling area the erosional area and the open shelf these settings describe the sediment dispersal and associated organic matter cycling in the lower yangtze river ecs shelf system

rhyolitic fallout and pyroclastic density current deposits from a phreatoplinian eruption in the eastern aegean sea greece abstract the kos plateau tuff consists of pyroclastic deposits from a major quaternary explosive rhyolitic eruption centred about 10 km south of the island of kos in the eastern aegean greece five main units are present the first two units a and b were the product of a phreatoplinian eruption the eruption style then changed to dry explosive style as the eruption intensity increased forming a sequence of ignimbrites and initiating caldera collapse the final waning phase returned to phreatomagmatic eruptive conditions unit f the phreatomagmatic units are fine grained poorly sorted and dominated by blocky vitric ash thickly ash coated lapilli and accretionary lapilli they are non welded and were probably deposited at temperatures below 100 c all existing exposures occur at distances between 10 km and 40 km from the inferred source unit a is a widespread 42 km from source thin upwind on kos to very thick downwind internally laminated dominantly ash bed with mantling sheet like form upwind unit a and the lower and middle part of downwind unit a are ash rich ash rich facies whereas the upper part of downwind unit a includes thin beds of well sorted fine pumice lapilli pumice rich facies unit a is interpreted to be a phreatoplinian fall deposit although locally the bedforms were influenced by wind surface water and topography the nature and position of the pumice rich facies suggests that the eruption style alternated between wet phreatoplinian and dry plinian during the final stages of unit a deposition unit b is exposed 10 19 km north of the inferred source on kos overlying unit a it is a thick to very thick internally stratified bed dominated by ash coated medium and fine pumice lapilli in an ash matrix unit b shows a decrease in thickness and grain size and variations in bedforms downcurrent that allow definition of several different facies and laterally equivalent facies associations unit b ranges from being very thick coarse and massive or wavy bedded in the closest outcrops to source to being partly massive and partly diffusely stratified or cross bedded in medial locations pinch and swell clast supported pumice layers are also present in medial locations in the most distal sections unit b is stratified or massive and thinner and finer grained than elsewhere and dominated by thickly armoured lapilli unit b is interpreted to have been deposited from an unsteady density stratified pyroclastic density current which decelerated and progressively decreased its particle load with distance from source condensation of steam during outflow of the current promoted the early deposition of ash and resulted in the coarser pyroclasts being thickly ash coated the distribution texture and stratigraphic position of unit b suggest that the pyroclastic density current was generated from collapse of the phreatoplinian column following a period of fluctuating discharge when the eruptive activity alternated between wet and dry the pyroclastic density current was transitional in particle concentration between a dilute pyroclastic surge and a high particle concentration pyroclastic flow unidirectional bedforms in unit b suggest that the depositional boundary was commonly turbulent and in this respect did not resemble conventional pyroclastic flows however unit b is relatively thick and poorly sorted and was deposited more than 19 km from source implying that the current comprised a relatively high particle concentration and in this respect did not resemble a typical pyroclastic surge

the pre ignimbrite phreato plinian and phreatomagmatic phases of the akdag zelve ignimbrite eruption in central anatolia turkey abstract the eruptive sequence of the 7 6 ma old akdag zelve ignimbrite azi eruption comprises five units totalling up to 50 m on akdag mountain they are in stratigraphic order a the main pumice fall deposit up to 10 m b the lower surge series up to 4 m c the upper pumice beds up to 0 8 m d the upper surge series up to 5 m and e the akdag zelve ignimbrite up to 40 m the main pumice fall deposit shows a second distal thickness maximum about 20 km from the source whereas the upper pumice beds form a simple nne extending fan the source area about 6 km north northeast of kaymakli is inferred from fallout thickness size and amount of lithic clasts depositional facies and flow directions of the surge deposits the main pumice fall deposit encloses accretionary lapilli up to 6 cm in size indicating a steady phreatomagmatic influence on the eruptive style from the very beginning the major surge sequence beneath the ignimbrite is similar to that of the 1400 yr b c minoan eruption on santorini greece and resembles the minoan b stratigraphic unit attributed to phreatomagmatic eruptions due to ingression of seawater into the conduit similarly the depositional environment of marshes and marginal flats of a lacustrine basin in cappadocia accounts for the external water supply and the generation of surges during the azi eruption estimates of eruption column height of 45 km indicate that the azi eruption ranks in the order of the 1956 bezymianny 1815 tambora and the waimihia plinian pumice eruption of new zealand volume estimates of the erupted tephra are on the order of 41 5 km 3 for the main pumice and 0 35 km 3 of the upper pumice

elemental and major biochemical changes across an oxidation front in a relict turbidite an oxygen effect abstract the elemental and major biochemical compositions of the relict f turbidite sampled in two cores from the madeira abyssal plain were determined this fine grained distal sequence occurs at ca 9 m core depth and includes a surficial oxidized horizon defined by a distinct color change oxygen diffused downward through sediments above this interface and in ca 10 kyr destroyed 80 of the organic substances that below the front had survived degradation in the presence of porewater sulfate for ca 140 kyr these deposits provide an opportunity to establish the extent and selectivity of oxic sedimentary degradation under natural conditions without the usual complications of bioturbation and varying sources or sedimentation rates in both cores a sample from the upper oxidized layer was compared to two samples from the underlying unoxidized layers the unoxidized sequences of both turbidities contained 0 93 1 02 wt organic carbon oc and 0 10 0 11 wt total nitrogen tn approximately 20 of the initial oc and 40 of the initial tn remained in the oxidized horizons with a consequent decrease in atomic c n ratio from ca 11 to ca 5 all samples gave very low yields of lignin phenols and comparable oc normalized yields of total aldoses and amino acids and indicated predominantly marine organic matter om and nonselective oxic degradation of these biochemical classes compositions of individual aldoses and amino acids generally were also similar in surface and deep sediments except that the oxidized horizons yielded markedly elevated 3 5x percentages of nonprotein amino acids this study clearly demonstrates that prolonged exposure to oz can lead to organic matter alteration which is far more extensive than that obtained with sulfate alone in comparison to early diagenesis however alteration of the measured biochemicals was largely nonselective such oxidation reactions could control the distribution and composition of organic matter in slowly accumulating continental rise and deep ocean environments

variability of lithofacial parameters of lower jurassic geothermal aquifer in the malanow region revealed by interpretation of geophysical well logs and seismic data the lower jurassic aquifer is the main target for exploitation of geothermal waters in the polish lowlands as it covers over 80 of the area of poland particularly favorable geothermal conditions dominate in the mogilno od trough central part of the polish lowlands where that aquifer occurs at greatest depth which results in high temperatures of geothermal waters the main lower jurassic reservoirs in that area are sinemurian pliensbachian and upper toarcian sandstones these sediments show high lithofacial variability which results in local changes of hydrogeothermal parameters such local variability can be effectively estimated using the seismic data and the interpretation of well logs both methods were used for determination of depths to the top surface of lower jurassic formation and of distribution of porosity and clay content which enabled the researchers to recognize the spatial arrangement of groundwater horizons the study area is a local structure within the mogilno od trough in the vicinity of malanow village this is a synclinal structure built of lower jurassic strata close to the turek salt pillow temperature of groundwater in that structure exceeds 80 c and favorable reservoir parameters ensure relevant discharge sandstone horizons show thicknesses over 50 m low clay contents and porosity around 0 15 0 20

integrated marine and terrestrial evidence for abrupt congo river palaeodischarge fluctuations during the last deglaciation we present a high resolution reconstruction of tropical palaeoenvironmental changes for the last deglacial transition 18 to 9 cal kyr bp based on integrated oceanic and terrestrial proxies from a congo fan core pollen grass cuticle pediastrum and dinoflagellate cyst fluxes sedimentation rates and planktonic foraminiferal 18o ratios u37k sea surface temperature and alkane alkenone ratio data highlight a series of abrupt changes in congo river palaeodischarge a major discharge pulse is registered at around 13 0 cal kyr bp which we attribute to latitudinal migration of the intertropical convergence zone itcz during deglaciation the data indicate abrupt and short lived changes in the equatorial precipitation regime within a system of monsoonal dynamics forced by precessional cycles the phases of enhanced congo discharge stimulated river induced upwelling and enhanced productivity in the adjacent ocean copyright 2001 john wiley sons ltd

constraints on the application of the mbt cbt palaeothermometer at high latitude environments svalbard norway abstract branched glycerol dialkyl glycerol tetraethers gdgts are membrane lipids of unknown bacteria that are ubiquitous in soil and peat two indices based on the distribution of these lipids in soils the cyclization of branched tetraethers cbt and the methylation of branched tetraethers mbt indices have been shown to correlate with soil ph and mean annual air temperature mat and soil ph respectively and can be used to reconstruct mat in palaeoenvironments to verify the extent to which branched gdgts in marine sediments reflect the distribution pattern on land and whether these proxies are applicable for palaeoclimate reconstruction in high latitude environments with a mat of

latest miocene and pleistocene ages of faulting determined by 40ar 39ar single crystal dating of airfall tuff and silicic extrusives of the erciyes basin central turkey evidence for intraplate deformation related to the tectonic escape of anatolia the ericiyes basin is a trans tensional basin situated 20 km north of the regional ecemis fault zone recently it has been hypothesized that faulting within the erciyes basin links with the ecemis fault zone further south as part of a regional central anatolian fault zone new 40ar 39ar dating of volcanic and volcaniclastic rocks adjacent to faults both along the margins and in the centre of the erciyes basin constrains the timing of basin inception and later faulting extensional faulting occurred along the eastern and western margins of the basin during the early messinian latest miocene sinistral and minor normal faulting were active along the axis of the basin during the early pleistocene these fault timings are similar to those inferred for the ecemis fault zone further south and support the hypothesis that faulting within the erciyes basin and the ecemis fault zone are indeed linked

210pb 137cs and 239 240pu in east china sea sediments sources pathways and budgets of sediments and radionuclides profiles of 210 pb 137 cs and 239 240 pu measured in 83 sediment cores collected from various sedimentary regimes in the east china sea were analyzed to elucidate the sources routes and budgets ofsediments as well as these radionuclides distributions ofsedimentation rates and nuclide inventories reveal alongshore transport ofsediments 137 cs and 239 240 pu from the mouth of the yangtze river toward the south largely confined to the inner shelf area water depth 6 70 m mass balance calculations suggest that the east china sea is a sink for the particle reactive 210 pb and 239 240 pu with about one sixth oftheir sedimentary budgets supplied via boundary scavenging in contrast due to lower affinity of 137 cs for particles and rapid turnover of the shelf water the east china sea serves as a source for 137 cs about two thirds ofthe cumulative input of 137 cs have been transported out ofthe east china sea leaving the remaining one third stored in the bottom sediments and the overlying water column as for the sediment budget mass balance cannot be established due to a shortfall in sediment supply of more than 30 based on a comparison between input terms documented thus far and the sedimentation flux derived from this study it is very likely that we have overestimated the sediment burial flux or that long distance transport from the yellow river s dispersal system to the east china sea is underestimated alternatively the imbalance could be explained by the discrepancy between sediment input and output on decadal to centennial timescales 7 2002 elsevier science b v all rights reserved

the nature origins and distribution of ash aggregates in a large scale wet eruption deposit oruanui new zealand abstract this study documents the processes and products of volcanic ash aggregation in phreatomagmatic phases of the 25 4 ka oruanui supereruption from taupo volcano new zealand detailed textural and stratigraphic relationships of aggregates are examined in six of the ten erupted units which range from relatively dry styles of eruption and deposition units 2 5 to mixed units 6 7 8 and dominantly wet unit 3 aggregate structures and grain size distributions shift abruptly over vertical scales of cm to dm providing diagnostic features to identify deposits emplaced primarily as vertical fallout or pyroclastic density currents pdcs the six categories of ash aggregates documented here are used to infer distinct volcanic and meteorological interactions in the eruption cloud related to dispersal characteristics and mode of emplacement our field observations support the notion of brown et al 2010 origin of accretionary lapilli within ground hugging density currents evidence from pyroclastic couplets on tenerife geol soc am bull 122 305 320 that deposits bearing matrix supported accretionary lapilli with concentric internal structure and abundant rim fragments are associated with emplacement of pdcs however on the basis of grain size distributions and field relationships it is inferred that these types of ash aggregates formed their ultrafine ash dominantly 100 km from vent it is inferred that ambient meteorological conditions play a more important role in ash fallout in these cases entrainment of moist air and distal subsidence and melting of ice carried by the plume are both likely to have contributed to the observed features of late stage aggregation in the drier phases of eruption these observations suggest that proximal column influenced aggregation processes which weaken with distance from source are overprinted by secondary later stage aggregation mechanisms farther downwind

palaeomagnetism of the cappadocian volcanic succession central turkey major ignimbrite emplacement during two short miocene episodes and neogene tectonics of the anatolian collage abstract the central anatolian volcanic province in cappadocia includes 13 high volume calc alkaline ignimbrite sheets emplaced by plinian eruptions within a succession the urgup formation after 10 ma recording the last phase of neotethyan subduction and accompanying emplacement of the tauride orogen in southern turkey to evaluate magnetostratigraphy in the context of recent revisions of the chronostratigraphy we have extended palaeomagnetic investigation to 32 new sites yielding significant chrm directions integrated rock magnetic and palaeomagnetic investigations identify magnetic remanence residing predominantly in ti poor titanomagnetites although secondary processes within the ignimbrite sheets notably post emplacement oxidation have locally produced hematisation expressed by composite irm spectra and variable reduction in intensity of magnetisation the ignimbrite sheets possess weak anisotropies of magnetic susceptibility ams mostly 3 of pyroclastic deposits during polarity chron c4r 1n between 9 31 and 9 43 ma subsequent activity from the acigol centre further to the south west cemilkoy gelveri gordeles and kizilkaya produced in excess of 620 km 3 of pyroclastic deposits during polarity chrons between 5 3 and 7 1 ma the younger incesu ignimbrite was sourced in the sultansazligi pull apart basin to the east during the gauss chron 2 58 3 60 ma all pre incesu ignimbrites are rotated uniformly anticlockwise and the overall reversed group mean direction of magnetisation is d i 170 8 52 4 n 9 r 8 91 95 5 4 k 91 the implied tectonic rotation in this sector of central anatolia 16 4 relative to eurasia is young and postdates the 5 3 7 1 ma acigol centre whilst largely predating emplacement of the incesu ignimbrite whilst rotational deformation within anatolia is young it proves to be distributed with a temporal variation from block to block it is embraced by a complex post miocene tectonic regime of strike slip and extension during tectonic escape and suction towards the hellenic arc to the west

the influence of oxic degradation on the sedimentary biomarker record i evidence from madeira abyssal plain turbidites free and ester bound lipid biomarkers were analysed in oxidised and unoxidised parts of four distinct turbidites from the madeira abyssal plain map which contained 1 to 2 organic carbon homogeneously distributed throughout the turbidites at the time they were deposited these turbidites are well suited to study the effects of oxic degradation on lipid biomarkers without the complicating influence of varying organic matter sources sedimentation rates or bioturbation one sample from the oxidised turbidite was compared with two samples from the unoxidised part of each turbidite postdepositional oxic degradation decreased concentrations of biomarkers by several orders of magnitude the ester bound lipids were degraded to a far lesser extent than their free counterparts were the extent of degradation of different compounds differed substantially within a specific class of biomarkers degradation also took place to a different extent altering their distributions this study shows that oxic degradation of the organic matter may have a profound effect on the biomarker fingerprint and may result in a severe bias in for example the interpretation of organic matter sources and the estimation of the palaeoproductivity of specific groups of phytoplankton

post depositional fracturing and subsidence of pumice flow deposits lascar volcano chile unconsolidated pyroclastic flow deposits of the 1993 eruption of lascar volcano chile have with time become increasingly dissected by a network of deeply penetrating fractures the fracture network comprises orthogonal sets of decimeter wide linear voids that form a pseudo polygonal grid visible on the deposit surface in this work we combine shallow surface geophysical imaging tools with remote sensing observations and direct field measurements of the deposit to investigate these fractures and their underlying causal mechanisms based on ground penetrating radar images the fractures are observed to have propagated to depths of up to 10 m in addition orbiting radar interferometry shows that deposit subsidence of up to 1 cm year 1 occurred between 1993 and 1996 with continued subsidence occurring at a slower rate thereafter in situ measurements show that 1 m below the surface the 1993 deposits remain 5 c to 15 c hotter 18 years after emplacement than adjacent deposits based on the observed subsidence as well as estimated cooling rates the fractures are inferred to be the combined result of deaeration thermal contraction and sedimentary compaction in the months to years following deposition significant environmental factors including regional earthquakes in 1995 and 2007 accelerated settling at punctuated moments in time the spatially variable fracture pattern relates to surface slope and lithofacies variations as well as substrate lithology similar fractures have been reported in other ignimbrites but are generally exposed only in cross section and are often attributed to formation by external forces here we suggest that such interpretations should be invoked with caution and deformation including post emplacement subsidence and fracturing of loosely packed ash rich deposits in the months to years post emplacement is a process inherent in the settling of pyroclastic material

thermal waters of central poland a case study from mogilno łodź trough poland thermal waters in poland occur in several different geothermal regions but the best parameters for their effective utilisation are connected i a with the area of polish lowlands one of the most prospective areas in the central part of polish lowlands for managing geothermal waters for various purposes is the area of mogilno od trough there are currently 2 operating geothermal heating plants and several others in various stages of development in this area water with a temperature of 97 5 c has been documented the aim of this article is to determine and visualise the potential of geothermal waters of the central poland mogilno od trough by providing the most important potential geothermal water parameters it is done by providing maps of potential temperature mineralization water outflow capacity thermal power and physicochemical analysis mineralization waters type the two most prospective geothermal reservoirs lower jurassic and lower cretaceous were analysed the results of the studies indicate that this area is characterised by very favourable hydrogeological conditions geothermal energy utilisation should be connected with lower jurassic and lower cretaceous reservoirs but it should be emphasised that a larger energy potential relates to waters from lower jurassic reservoir however they are characterised by high water mineralisation up to 170 g l waters of lower cretaceous reservoir are characterised by not only lower mineralisation up to 100 g l but also lower temperature max 75 c the highest temperatures in the lower jurassic are recorded in the axial part of the trough where locally they exceed in the top of formation 100 c on the other hand in edge trough zones water temperatures are 30 40 c the actual geothermal potential of the area is much higher than currently used for example potential discharge of wells is to over 400 m3 h in the lower cretaceous and up to over 500 m3 h in the lower jurassic

distribution of hopanoids along a land to sea transect implications for microbial ecology and the use of hopanoids in environmental studies bacteriohopanepolyols bhps are lipid constituents of diverse bacteria and have great potential as taxonomically and environmentally diagnostic biomarkers in order to examine their environmental behavior and potential for tracing biogeochemical processes we analyzed bhps and geohopanoids the diagenetic products of bhps in soils and surface sediments from the middle yangtze river catchment to the east china sea ecs shelf these data are compared to an up to date survey of bhp distributions in soils including regions collectively covering the arctic temperate subtropics and tropics regional climatic differences particularly temperature likely exert an important control on bhp distributions in soils in the aquatic river estuary shelf setting bhp concentrations and structural diversity are substantially lower than in soils suggesting that in aquatic environments either bacterial biodiversity is lower or there is not the same requirement for hopanoid synthesis however different aquatic regimes vary substantially high bhp diversity and enhanced bhp production occur in the biogeochemically dynamic yangtze estuary whereas bhp distribution is uniform with much less structural diversity in the oligotrophic ecs open shelf the rsoil index based on the relative abundances of soil marker bhps against bacteriohopanetetrol is suggested as a new approach to trace soil organic matter input into marine sediments the rsoil indices decrease from the river to the ecs correlating strongly with branched and isoprenoid tetraether indices and moderately correlating with 13c of organic carbon values and the concentrations of higher plant biomarkers demonstrating their ability to trace soil organic matter inputs at least to the ecs

the eruptive center of the late quaternary laacher see tephra about 5 km3 of phonolite magma were erupted 11 000 years ago in the laacher see area in plinian and vulcanian eruptions the eruptive vents for all tephra in dispute for over 200 years must have been located entirely within the laacher see basin because 1 all deposits are thickest in the tuffring surrounding the basin with one exception pyroclastic flow deposits are thickest 2 to 6 km away from the rim of the basin having ponded in radial valleys three plinian fallout layers show minor secondary thickness maxima 12 to 16 km east of laacher see 2 axes of all depositional fans and single tephra sheets converge in the laacher see basin 3 diameters of both lithic and pumice clasts reach their maxima in outcrops close to laacher see volcano 4 directions of asymmetric ballistic impact sags indicate the laacher see basin as source area 5 the dimension of laacher see crater roughly corresponds to the erupted volume of phonolitic tephra 5 3 km3 magma dre and lithic clasts 0 7 km3 6 xenolith types are consistent with an eruptive center within the laacher see basin 7 the systematic chemical and mineralogical zonation of the tephra deposits from highly differentiated aphyric phonolite at the base to highly phyric mafic phonolite at the top strongly suggests eruption from a single compositionally zoned magma column 8 several lines of evidence indicate migration of the main eruptive focus from the south to the north during the later part of the eruption both vents however being confined within the laacher see basin

recent sediment accumulation and carbon burial in the east china sea 1 sediment and carbon budgets were constructed for the east china sea ecs shelf based on up to date data the total annual sediment flux in the ecs shelf is approximately 96 of the terrestrial input there is high retention of sediment on the ecs shelf owing to the broad nature of the shelf edge i e 500 600 km and because of an along shore sediment dispersal path driven by the east china sea coastal current ecscc and the taiwan warm current twc organic carbon oc burial was also observed based on the results for sediment accumulation and the oc proportion in surface sediment a total of 7 4 106 t of oc is preserved in shelf sediments source discrimination of sedimentary oc revealed that the percentage of oc burial for both terrigenous and marine oc sources was higher than the global mean value at 10 and 5 5 respectively presumably owing to high sediment accumulation high oc flux to sediment in the estuary and shelf break suggests that riverine discharge and upwelling of the kuroshio intrusion are key factors regulating oc burial over the shelf estimated using a mass balance model 15 20 of the carbon inventory is buried in the shelf sediment while 80 of the carbon inventory must be transported out of shelf area in the form of dissolved carbon organic and inorganic the accumulation of carbon in sediments and the outflow of dissolved carbon sustain a high carbon sink in the ecs

control of organic carbon accumulation in the late quaternary equatorial atlantic ocean drilling program sites 664 and 663 productivity versus terrigenous supply organic geochemical records of the last 940 kyr are presented for equatorial atlantic ocean drilling program odp sites 663 and 664 and discussed with regard to the development of ocean productivity and african paleoclimate proportions of marine and terrigenous organic matter om are estimated from elemental pyrolytic isotopic and petrologic data spectral analyses reveal a strong power at the eccentricity and obliquity band indicating a close response of tropical organic sedimentation to the climatic evolution at high latitudes the orbital covariance of organic carbon with biogenous opal and terrigenous records favor that glacially enhanced dust supply and surface water mixing were primary controls for deposition of organic carbon wind borne supply of terrigenous om contributes 26 to 55 and 0 to 39 to the bulk om based on microscopic and isotopic records respectively admixture of c4 plant matter was approximated to contribute up to 16 to the bulk organic fraction during peak glacial conditions

fall out and deposition of volcanic ash during the 1979 explosive eruption of the soufriere of st vincent abstract the 1979 explosive activity of soufriere volcano st vincent commenced on april 13th and continued for two weeks producing eleven eruption columns the activity produced air fall ash with abundant accretionary lapilli plus minor pyroclastic flows and base surge deposits the dispersal of the columns was observed by an sms 1 geostationary satellite all but two of the plumes were dispersed entirely to the east the last event on april 26th formed a minor lobe to the east and a major lobe to the south southeast the april 26th column was observed to rise to 8 km within five minutes and ascended to a maximum of 14 km in the next hour the magma discharge rate was greater than 3000 m3 s the plume expanded at a rate of 4000 km2 hr and was dispersed at a mean velocity of 15 m s the ash deposits show bimodal grain size distribution with 95 of the ash collected being sub 1 mm diameter modelling of the ash fall out has allowed interpretation of grainsize parameters in a quantitative manner the fall velocities of ash particles appear to have been reduced by turbulence and downwind ascent of the plume which is attributed to fallout of ash reducing the plume density the coarse population of the april 26th deposit displayed a systematic change in md and away from source the fine mode displays uniform md and everywhere and is interpreted as having been deposited in the form of accretionary lapilli

atlases of geothermal waters and energy resources in poland the paper presents results of geothermal projects carried out in the last 23 years by the interdisciplinary research team at the agh university of science and technology in cooperation with numerous scientific institutions published in the form of geothermal atlases in different parts of poland for many years the department of fossil fuels at the faculty of geology geophysics and environmental protection agh university of science and technology has conducted the fundamental research and implementation work aiming at the selection of optimum areas for utilization of geothermal waters and energy over the years a methodology of estimation of geothermal resources with use of advanced techniques and numerical modeling has been developed recapitulation of the studies of the occurrence and utilization of geothermal waters and energy within geological units of the polish lowlands carpathians and carpathian foredeep has been reflected in seven atlases the atlases represent a result of interdisciplinary constructive cooperation of specialists from various often remote fields of knowledge fundamental and technological in nature including geologists geophysicists hydrogeologists geochemists drilling engineers heat engineers and many other specialists the atlases enable the selection of the most promising areas for utilization of geothermal waters and energy in poland the best geothermal conditions are predicted in the polish lowlands and podhale region although in many areas of the carpathians and the carpathian foredeep favorable geothermal conditions also occur

terrestrial organic carbon contributions to sediments on the washington margin elemental and stable carbon isotopic compositions and biomarker concentrations were determined in sediments from the columbia river basin and the washington margin in order to evaluate geochemical approaches for quantifying terrestrial organic matter in marine sediments the biomarkers include an homologous series of long chain n alkanes derived from the surface waxes of higher plants phenolic and hydroxyalkanoic compounds produced by cuo oxidation of two major vascular plant biopolymers lignin and cutin all marine sediments including samples collected from the most remote sites in cascadia basin showed organic geochemical evidence for the presence of terrestrial organic carbon using endmember values for the various biomarkers determined empirically by two independent means we estimate that the terrestrial contribution to the washington margin is 60 for shelf sediments 30 for slope sediments and decreases further to 15 in basin sediments results from the same geochemical measurements made with depth in gravity core 6705 7 from cascadia seachannel suggest that our approach to assess terrestrial organic carbon contributions to contemporary deposits on the washington margin can be applied to the study of sediments depositing in this region since the last glacial period

mineral compositional and textural evidence for magma mingling in the saraykent volcanics abstract upper cretaceous paleocene calc alkaline dacitic and rhyodacitic lava flows and domes are exposed in the saraykent yozgat region within central anatolian crystalline complex cacc saraykent volcanics are generally plagioclase hornblende biotite titanomagnetite quartz augite phyric subrounded vesicular magmatic enclaves ranging from a few millimeters to a few centimeters in size are present in the saraykent dacites the enclaves are mainly holocrystalline and have similar mineral assemblage to the host dacites almost all phases in saraykent volcanics exhibit varying degrees of disequilibrium features indicative of magma mingling plagioclase phenocrysts display sieved and normal type populations a wide range in rim compositions and oscillatory zoning maximum core to rim compositional change in sieved rhyodacite plagioclases is up to 24 mol increase in an some plagioclase core compositions are unusually ca rich they range from an27 to an75 for the saraykent dacites and from an30 to an66 for the saraykent rhyodacites hornblende and biotite phenocrysts have reaction rims indicating disequilibrium crystallization with magma both hornblende and biotite crystals show reverse zoning in terms of decreasing mg mg fe quartz phenocrysts are corroded and embayed presence of normally and reversely zoned augites in the same sample and high ti high al augites more comparable with basaltic compositions are other lines of evidence for disequilibrium the enclave hornblendes are both edenitic and pargasitic the latter being more typical of mafic compositions the enclave biotite crystals have higher mg mg fe2 ratios than the host dacite biotite crystals and display normal reverse and oscillatory zoning plagioclase core compositions vary between an44 and an55 in the enclaves although the development of sieve texture in plagioclase and reaction rims on mafic minerals may be attributed to decompression this cannot explain the observed compositional change and normal type of plagioclase in the same sample similarly a cognate i e fractionation origin for the enclaves can be suggested due to their mineralogical similarity to the host dacite however other criteria such as oscillatory zoning and unusually calcic cores of plagioclases heterogeneity of plagioclase rims resorbed and embayed phenocrysts and augite compositions indicating a more mafic magma are enough to support the suggestion that magma mingling was a viable process in the generation of the saraykent volcanics

mechanistic controls on diverse fates of terrestrial organic components in the east china sea terrestrial carbon transferred from the land to sea is a critical component of the global carbon cycle a range of geochemical proxies has been developed to fingerprint the fate of terrestrial organic matter tom in marine sediments however discrepancies among different proxies limit our ability to quantify and interpret the terrestrial signals in marine sediments with consequences for the investigation of both the modern carbon cycle and past environmental change to mechanistically understand these discrepancies we examined the distributions of a range of terrestrial proxies and their aquatic counterparts i e marine proxies in the yangtze river east china sea yr ecs shelf system where tom experiences extensive modification during transport and burial tom proxies in the yr ecs system collectively fit a power law model but with distinct attenuation rates the a values for individual molecular proxy groups among a range of tom proxies the modeled a values decrease in the order soil marker bhps triterpenols lignin hmw n alkanols branched gdgts hmw n alkanes for biomarkers and rsoil bit tomiso for proxies tracing tom rapid loss of tom components through dissociation in the narrow estuary followed by oxidation over the wide open shelf are best described by power curves inherent chemical reactivity i e the number of functional groups responses to hydraulic sorting and in situ production regulate the individual attenuation rates of them chemical reactivity plays the most important role on proxy behavior supported by a strong correlation between a values and standard molal gibbs energies both physical protection and chemical reactivity fundamentally control the overall behavior of tom components with the relative importance being setting dependant the former is relatively important in the estuary whereas the later is the primary control over the open shelf moreover regional variation of different marine counterparts is also significant over the river ecs shelf system seemingly regulated by regional nutrient distributions therefore for tom estimates using molecular ratio approaches the specific behavior of individual terrestrial components and marine counterparts and the physical biological and chemical characteristics of depositional settings all need to be considered

disentangling marine soil and plant organic carbon contributions to continental margin sediments a multi proxy approach in a 20 000 year sediment record from the congo deep sea fan abstract a 20 kyr long sediment sequence from the congo deep sea fan core geob 6518 1 one of the world s largest deep sea river fans has been analysed for bulk and molecular proxies in order to reconstruct the marine soil and plant organic carbon oc contributions to these sediments since the last glacial maximum the bulk proxies applied c n ratio and 13 c org ranged from 10 to 12 5 and from 24 5 to 21 vpdb respectively as molecular proxies concentrations of marine derived alkenones and terrestrial derived odd numbered n alkanes were used which varied between 0 2 and 4 g g dry weight sediment in addition the branched vs isoprenoid tetraether bit index a proxy for soil organic matter input was used which varied from 0 3 to 0 5 in this core application of binary mixing models based on the different individual proxies showed estimates for terrestrial oc input varying by up to 50 due to the heterogeneous nature of the oc application of a three end member mixing model using the 13 c org content the c n ratio and the bit index enabled the distinction of soil and plant organic matter as separate contributors to the sedimentary oc pool the results show that marine oc accounts for 20 to 40 of the total oc present in the deep sea fan sediments over the last 20 kyr and that soil oc accounts for about half 45 on average of the oc present this suggests that soil oc represents the majority of the terrestrial oc delivered to the fan sediments accumulation rates of the plant and soil oc fractions over the last 20 kyr varied by a factor of up to 5 and are strongly related to sediment accumulation rates they showed an increase starting at ca 17 kyr bp a decline during the younger dryas peak values during the early holocene and lower values in the late holocene this pattern matches with reconstructions of past central african humidity and congo river discharge from the same core and revealed that central african precipitation patterns exert a dominant control on terrestrial oc deposition in the congo deep sea fan marine oc accumulation rates are only weakly related to sediment accumulation rates and vary only little over time compared to the terrigenous fractions these variations are likely a result of enhanced preservation during times of higher sedimentation rates and of relative small fluctuations in primary production due to wind driven upwelling

assessments on the stability of natural slopes prone to toe erosion and man made historical semi underground openings carved in soft tuffs at zelve open air museum cappadocia turkey abstract the zelve open air museum consisting of three valleys is one of the oldest historical semi underground settlements in the cappadocia region of turkey which was designated as a world heritage site in 1985 by unesco particularly in the first valley there are a lot of underground openings of different sizes carved in a soft tuff next to the valley cliffs used for cliff settlement in the past and several antique churches with some geo engineering problems in addition steep natural slopes in this valley are prone to toe erosion resulting in stability problems in this study it is aimed to investigate engineering characteristics of the surrounding tuff and factors affecting them and to assess the effect of rate of toe erosion on the stability of steep valley slopes and structural stability of some selected typical underground openings with large spans subjected to spalling for these purposes some observational experimental and numerical modelling studies were conducted experimental results indicate that strength and deformability properties of the weak tuff surrounding the openings drastically reduce when it becomes wet or saturated this situation suggests that possibility of occurrence of failures is expected to be higher in rainy seasons due to increase in water content of the tuff experimental results also suggest that spalling commonly observed in the valley is related with freezing thawing and wetting drying cycles in nature and that the process of freezing and thawing accelerates further the degradation of the rock the long term measurements at selected locations suggest that erosion in the tuff is important which increases particularly in winter and spring seasons and results in the loss of support accelerating the occurrence of further slope failures the 2 d numerical solutions indicate that no significant change in shear and tensile stresses in steep valley slopes prone to toe erosion would be expected after 100 years however the solutions obtained from the 500 and 1000 year scenarios suggest that failure zones due to the tensile stresses would develop in the form of slabs with thicknesses of 50 60 cm and 90 100 cm respectively which would break off from the slope and fall down the results from 3 d numerical solutions indicate that failure yield zone resulting from tensile stresses around the semi underground openings will develop parallel to the sidewalls these results confirm the observed spalling of the tuff in the form of slabs parallel to the walls of the openings

twentieth century proxy records of temperature and soil organic matter input in the drammensfjord southern norway abstract the drammensfjord in southern norway is an enclosed anoxic basin with a laminated sedimentary record the fjord is a transition area between the marine and terrestrial environments and thus its sedimentary archive contains information on both environments in order to reconstruct recent environmental changes in southern norway two sediment cores covering the last 90 years were analyzed we used the branched versus isoprenoid tetraether bit index as an indicator of terrestrial organic mater input and compared it to the stable carbon isotopic composition of total organic carbon 13 c toc the 13 c toc and bit index show opposing trends with 13 c toc indicating an increase in terrestrial input while the bit index suggests a decrease towards the present this contradiction is probably due to the different sources reflected by 13 c toc vegetation soil and anthropogenic input and the bit index only soil organic matter input in addition an increase in the recycling of respired co 2 within the fjord s water column could have depleted the 13 c toc of the marine component towards more negative values thus seemingly indicating an increase in terrestrial input whilst the bit index could have been affected by a reduction of riverine input and or an increase in archaeal biomass production the tetraether index of lipids with 86 carbons tex 86 was determined as a proxy for past water surface temperatures while some of the signal could be coming from the chemocline our results suggest that tex 86 indicates surface upper 25 m temperatures moreover tex 86 temperature patterns seem to follow variations in the historical record of averaged spring to fall oslo air temperature relatively closely suggesting the signal is produced during this period therefore tex 86 temperature records of fjord sediment cores can potentially be a useful tool in reconstructing past variations of coastal climates

multiple sources and extensive degradation of terrestrial sedimentary organic matter across an energetic wide continental shelf the fate of organic carbon in marine sediments is closely linked to atmospheric co2 concentrations and thus to climate variability over geological time scales the east china sea ecs is characterized not only by massive terrestrial organic matter tom inputs from the yangtze changjiang river but also by a shallow 500 km continental shelf with widespread relict sands such that it is distinct from other continental margins we examine the diagenesis of sedimentary tom and the impacts of relict sands on tom in the ecs the results reveal that bulk 13corg values correlate with terrestrial biomarker concentrations in muddy and accumulative areas in contrast depleted 13corg values around 24 5 co occur with almost absent terrestrial biomarkers in sandy erosional areas we suggest that mixing of contemporary tom and marine om dominates in the muddy accumulative shelf areas whereas a putative relict om associated with relict sands appears to be significant in many sandy erosional shelf areas given the global occurrence of relict sands a persistent amount of relict oc e g 0 1 may complicate tom budget calculations in addition our observations reveal that tom is extensively partitioned and degraded in the estuary and continues to be partitioned and degraded during the along shore and across shelf transport which is reflected by decreases in terrestrial biomarker concentrations and increases in degradation indices this study highlights the unique and dynamic role of shallow and wide continental shelves with massive relict sands on tom cycling

petrology of organic matter in modern and late quaternary deposits of the equatorial atlantic climatic and oceanographic links abstract organic petrologic and geochemical analyses were performed on modern and quaternary organic carbon poor deep sea sediments from the equatorial atlantic the study area covers depositional settings from the west african margin odp site 959 through the equatorial divergence odp site 663 to the pelagic equatorial atlantic response of organic matter om deposition to quaternary climatic cycles is discussed for odp sites 959 and 663 the results are finally compared to a concept established for fossil deep sea environments littke r sachsenhofer r f 1994 organic petrology of deep sea sediments a compilation of results from the ocean drilling program and the deep sea drilling project energy and fuels 8 1498 1512 organic geochemical results obtained from equatorial atlantic deep sea deposits provide new aspects on the distribution of sedimentary om in response to continental distance atmospheric and oceanographic circulation and depositional processes controlling sedimentation under modern and past glacial interglacial conditions the inventory of macerals in deep sea deposits is limited due to mechanical breakdown of particles degree of oxidation and selective remineralization of labile mostly marine om nevertheless organic petrology has a great potential for paleoenvironmental studies especially as a proxy to assess quantitative information on the relative abundance of marine vs terrigenous om discrepancies between quantitative data obtained from microscopic and isotopic 13 c org analyses were observed depending on the stratigraphic level and depositional setting strongest offset between both records was found close to the continent and during glacial periods suggesting a coupling with wind born terrigenous om from central africa since african dust source areas are covered by c4 grass plants supply of isotopically heavy om is assumed to have caused the difference between microscopic and isotopic records

organic matter in river influenced continental margin sediments the land ocean and climate linkage at the late quaternary congo fan odp site 1075 1 late quaternary sections 1 2 ma of odp site 1075 from the congo deep sea fan are investigated to reconstruct variations of terrigenous organic matter supply to the eastern equatorial atlantic to characterize the organic matter om with regard to marine and terrigenous amounts we used elemental analysis c n s stable carbon isotopes bulk 13corg rock eval pyrolysis and terrigenous biomarkers lignin phenols from cuo oxidation the records of total organic carbon toc contents corg ntot ratios bulk om degradation rates corg corg and the ratios of hydrocarbons hc from low mature versus hc from high mature om lm hm reveal pronounced cyclic changes in om abundance preservation and reactivity that are closely related to the precessional controlled record of insolation and thus to variations in upwelling intensity and fluvial run off primary productivity off the congo is stimulated by both enhanced nutrient supply in response to trade induced upwelling during arid african climates insolation minima and fluvial nutrient delivery during humid stages following insolation maxima especially due to the contribution of dissolved silica that is taken up preferably by diatoms however results stemming from a multiparameter approach reveal that the fluvial supply of degraded om and black carbon bc associated with fine grained sediments from soil erosion is a decisive factor for the preservation of marine om and in addition significantly influences the geochemical signature of bulk and terrigenous om riverine and eolian supply of c4 plant matter as well as enhanced concentrations of bc during arid and arid to humid transitional climate stages may lead to a severe underestimation of terrigenous organic carbon if its amount is calculated from bulk isotopic ratios using binary end member models during the humid stages it is the massive supply of 13c enriched soil om with low corg ntot ratios that may suggest a mainly marine composition of bulk om in fact terrigenous om governs bulk om geochemical signatures in the sediments of the congo deep sea fan a result that is contradictory to earlier studies especially to the conventional interpretation of the bulk 13corg signal

palaeomagnetism and magnetic properties of the cappadocian ignimbrite succession central turkey and neogene tectonics of the anatolian collage abstract the cappadocian ignimbrite succession of central southern anatolia comprises at least nine major and two minor calc alkaline rhyolitic sheets emplaced at 1 2 ma intervals between 11 2 and 1 1 ma it records the last phase of neotethyan subduction during final emplacement of the tauride orogen in southern turkey this study reports magnetostratigraphy and describes associated rock magnetic properties remanence resides in ti poor titanomagnetites haematisation is locally produced by post emplacement oxidation but does not contribute significantly to the palaeomagnetic signature although secondary processes within the ignimbrite sheets have produced composite isothermal remanent magnetisation spectra and variable intensities of magnetisation weak anisotropy of magnetic susceptibility describes tensors with maximum axes close to bedding and minimum axes perpendicular to this plane directions of kmax with weak imbrication mostly suggest flow away from centres of eruption located by gravity and remote sensing older ignimbrites upper and lower goreme akdag zelve from the cardak centre are all of normal polarity later ignimbrites partly erupted from the derinkuyu centre comprise the sarimaden r cemilkoy r tahar r kizilkaya r incesu n and valibaba sofular r ignimbrites the overall reversed group mean is d i 174 51 n 10 units r 9 84 95 6 6 k 55 and all magnetisation directions from the upper goreme 9 0 ma onwards are rotated anticlockwise with respect to eurasian and african palaeofields this sense of rotation characterises most of central anatolia and averages 9 5 in this sector the rotation rate from 8 to 1 ma bp was 1 25 ma but it appears to have accelerated during the latter part of the quaternary to about an order higher than rates determined from gps rotation has resulted from extrusion of fault blocks during tectonic escape of the anatolian collage to the southwest and followed crustal thickening as the afro arabia plate has continued to impinge differentially into eurasia cenozoic magnetic inclinations are systematically shallower across anatolia than inclinations expected from the geocentric dipole model and the apparent polar wander of bordering major plates only part of this difference 400 km can be accommodated by northward movement and crustal thickening in central anatolia since mid miocene times shallow inclinations observed in the aegean region extend into turkey they are observed in young volcanics and appear to reflect a regional geomagnetic anomaly the pattern of neotectonic declinations across anatolia shows rotations that are strongly anticlockwise rotated in the east near the arabian pincer but diminish towards the west to become zero or slightly clockwise at the western extremity of the collage rotations also seem to become generally younger towards the south crustal deformation has therefore been distributed and the net effect of terrane extrusion to the west and south has been to expand the curvature of the tauride arc and by inference the cyprus arc

selective aerobic and anaerobic degradation of lipids and palynomorphs in the eastern mediterranean since the onset of sapropel s1 deposition abstract selective degradation of organic matter in sediments is important for reconstructing past environments and understanding the carbon cycle here we report on compositional changes between and within lipid classes and kerogen types represented by palynomorph groups in relation to the organic matter flux to the sea floor and oxidation state of the sediments since the early holocene for central eastern mediterranean site abc26 this includes the initially oxic but nowadays anoxic presapropelic interval the still unoxidised lower part of the organic rich s1 sapropel its postdepositionally oxidised and nowadays organic poor upper part as well as the overlying postsapropelic sediments which have always been oxic a general 2 3 times increase in terrestrial and marine input during sapropel formation is estimated on the basis of the total organic carbon toc pollen spore dinoflagellate cyst n alkane n alkanol and n alkanoic acid concentration changes in the unoxidised part of the sapropel the long chain alkenones 1 15 diols and keto ols loliolides and sterols indicate that some plankton groups notably dinoflagellates may have increased much more apart from the terrestrial and surface water contributions to the sedimentary organic matter anomalous distributions and preservation of some c 23 c 27 alkanes alkanols and alkanoic acids have been observed which are interpreted as a contribution by organisms living in situ comparison of the unoxidised s1 sapropel with the overlying oxidised sapropel and the organic matter concentration profiles in the oxidised postsapropelic sediments demonstrates strong and highly selective aerobic degradation of lipids and palynomorphs there seems to be a fundamental difference in degradation kinetics between lipids and pollen which may be possibly related with the absence of sorptive preservation as a protective mechanism for palynomorph degradation the n alkanes impagidinium and nematosphaeropsis are clearly more resistant than toc the n alkanols and n carboxylic acids are about equally resistant whereas the pollen all other dinoflagellate cysts and other lipids appear to degrade considerably faster which questions the practice of normalising to toc without taking diagenesis into account selective degradation also modifies the relative distributions within lipid classes whereby the longer chain alkanes alcohols and fatty acids disappear faster than their shorter chain equivalents accordingly interpretation of lipid and palynomorph assemblages in terms of pre or syndepositional environmental change should be done carefully when proper knowledge of the postdepositional preservation history is absent two lipid based preservation proxies are tested the diol keto ol oxidation index based on the 1 15c 30 diol and keto ols doxi and the alcohol preservation index api whereby the former seems to be the most promising

correlation of ignimbrites in the central anatolian volcanic province using zircon and plagioclase ages and zircon compositions abstract episodes of high eruptive fluxes 10 3 km 3 year in continental environments are associated with magmatism related to subduction post orogenic collapse intra plate hot spots or rifting during such episodes voluminous ignimbrite deposits are produced which cover landscapes over 10 4 10 5 km 2 in such sequences brief eruptive recurrence and chemical similarity limit the applicability of geochronological and geochemical correlation methods here we present complementary geochronological data 40 ar 39 ar plagioclase eruption and 206 pb 238 u zircon crystallization ages for ignimbrites from the miocene holocene central anatolian volcanic province cavp in addition we successfully employed zircon geochemistry trace elements oxygen isotopes as an alteration resistant indicator to correlate rhyodacitic to rhyolitic ignimbrites whose eruption age differences are too brief to be resolved by 40 ar 39 ar geochronology by applying this method we dismiss previous correlations between stratigraphic members i e sofular and gordeles sofular and sarimadentepe but demonstrate close relationships for other cavp ignimbrites i e kavak units 1 to 4 cemilkoy ignimbrite and overlying fallout deposits our chronostratigraphy reveals two previously unrecognized eruptive pulses at 9 8 ma and 7 5 ma which are characterized by increasing magmatic temperatures 75 100 c within each cycle despite a long term 10 ma eruptive productivity that is about one order of magnitude smaller than in other magmatically active continental plateaus the cavp achieved high eruptive fluxes during brief 1 2 ma intervals

relationships between mineral surfaces and organic carbon concentrations in soils and sediments abstract relationships between mineral specific surface area and organic carbon oc concentration are examined for sediments and soil a horizons from throughout the world i found published elsewhere that continental shelf sediments from many different regions exhibit downcore loss of oc to a refractory background level which shows a consistent relationship with mineral surface area slope 0 86 mg m 2 oc this trend is equivalent to a monolayer of organic matter over all surfaces and is termed the monolayer equivalent me level sediments and soils from other environments are compared to this empirically derived relationship several continental slope areas show extension of this relationship to considerable depth marked excesses of oc above this trend which persist downcore were found in sediments with high carbonate mineral content or slope sediments with low dissolved oxygen concentrations in the overlying water column about half of the soils examined also adhered to this relationship while soils with high carbonate content low ph or poor drainage showed oc concentrations higher than the me level oc concentrations below the me level are found in deltaic regions and areas with low organic matter delivery such as the deep sea or arid soils the nature of mineral surfaces was examined using n2 adsorption desorption isotherms and most surface area was found to be present as pores with

surface area control of organic carbon accumulation in continental shelf sediments the relationship between organic carbon oc and grain size found in most continental shelf sediments is here reinterpreted in terms of the surface area of the sediments cores from many north american shelf environments show downcore decreases in oc to similar refractory background concentrations if expressed relative to the surface area of the sediments this consistent concentration is 0 86 mg oc m 2 which is equivalent in concentration to a monolayer of organic matter coating all mineral surfaces a more global collection of sediment water interface samples show that this relationship is even more extensive with exceptions occurring in areas of very high riverine sediment input organic pollution or low oxygen water columns density separations indicate that organic matter is largely adsorbed to mineral grains the microtopography of surfaces was examined with n2 sorption and most surface area was found to be inside pores of 10 nm width these data lead to a hypothesis that organic matter is protected by its location inside pores too small to allow functioning of the hydrolytic enzymes necessary for organic matter decay such protection would likely work in concert with other protection mechanisms such as humification this consistent surface area correlation with oc concentration may explain control of spatial and temporal variations in oc burial rates by sedimentation rates the pore protection hypothesis provides a causal mechanism for this observed control

the dispersal of sedimentary terrestrial organic matter in the east china sea ecs as revealed by biomarkers and hydro chemical characteristics terrestrial organic matter tom in surface sediments from the lower yangtze river and adjacent east china sea ecs shelf was characterized using elemental stable carbon isotope and molecular analysis the results show that it is heterogeneous and derives from various sources in the lower river transect rc transect and inner shelf transect zj transect but is more homogeneous and presumably derives from a single source in the cross shelf transect pn transect the trends in sedimentary tom abundance indicated by high molecular weight n alkane abundances and distributions lignin derived products 13c values of total organic carbon 13ctoc and ratio of toc to total nitrogen c n suggest a southward off estuary transport mode of tom along the inner shelf transect while counter intuitively the opposite or no trend in tom off estuary transport occur along the cross shelf transect we therefore suggest that yangtze discharged om is transported southwards along the zhejiang fujian coast zj transect and enters the southern okinawa trough via near bottom currents from where it is ultimately delivered back upslope to the middle shelf by the kuroshio invading water consistent with the hydro chemical characteristics of the ecs