classification of huminite iccp system 1994 abstract in the new classification iccp system 1994 the maceral group huminite has been revised from the previous classification iccp 1971 int handbook coal petr suppl to 2nd ed to accommodate the nomenclature to changes in the other maceral groups especially the changes in the vitrinite classification iccp 1998 the new vitrinite classification iccp system 1994 fuel 77 349 358 the vitrinite and huminite systems have been correlated so that down to the level of sub maceral groups the two systems can be used in parallel at the level of macerals and for finer classifications the analyst now has according to the nature of the coal and the purpose of the analysis a choice of using either of the two classification systems for huminite and vitrinite this is in accordance with the new iso coal classification that covers low rank coals as well and allows for the simultaneous use of the huminite and vitrinite nomenclature for low rank coals

geomorphology and palaeoclimatology of some upper cretaceous palaeosols in central india abstract the late cretaceous maastrichtian lameta formation exposed around jabalpur in central india comprises a pedogenically modified fluvial succession accumulation of early diagenetic calcite cement during penecontemporaneous pedogenesis has transformed the fluvial sandstones into calcareous sandstones the microscopic features of the palaeosol material include floating grain fabric root traces laminated micrite microspar micrite envelopes and corona structures illuvial clay envelopes poikilotopic spars and minor amounts of siliceous grain and void cutans the palaeosol profiles of the lameta formation can be classified into eleven different types nine of which are comparable to present day mature aridisols and two to inceptisols nine to thirteen palaeosol profiles are present in the individual sections of the lameta formation within the study area each profile comprises two to four distinct pedohorizons arranged in vertical succession there are six types of pedohorizons present in the area of study namely partly altered hosts light coloured and poorly cemented horizons horizons with root traces and root related alterations horizons of subspherical glaebules horizons of platy fused glaebules and subhorizontal root traces and horizons with solution features they show many characteristics similar to the present day soil horizons for example those termed c bk k a and e by pedologists the palaeosol characteristics show correspondence to the nature of fluvial channel migration and the depth of the groundwater table controlled by the geomorphic setting a shallow groundwater table favoured the development of rootmat bearing and gleyed horizons horizons with vertical root traces and glaebules occur where the groundwater table was low mature and thin palaeosols developed in those parts of the lameta fluvial tract that were characterized by stable channels and wide floodplains in contrast thin and comparatively immature soils occurred in the parts where laterally migrating channels were operative the characteristics of the lameta palaeosols suggest that a hot and semiarid climate prevailed for most of the time represented by the lameta formation but short term wet spells occurred during the initial and the terminal phases of the lameta accumulation the low latitudinal palaeoposition of india and the absence of the palaeo monsoon circulation might have produced the hot and semiarid climatic setting during this time

evolution of neogene calc alkaline to alkaline volcanism in the aliaga foca region western anatolia turkey abstract in the foca region a complete miocene volcano sedimentary succession outcrops this succession includes a well developed central volcano gradually interdigitating with flank erruptions and a lacustrine sedimentary succession the dumanlidag volcano consists of three laterally and vertically interdigitating rock associations the yuntdag volcanics the foca volcanics and the aliaga limestones the lowermost unit is the yuntdag volcanics comprising dominantly andesitic and trachyandesitic lava flows domes and dykes and interbedded blocky pyroclastic flow deposits these different facies together form a central volcano with a caldera structure surrounding its summit the andesitic volcanic succession grades laterally into and is overlain by the rhyolitic foca volcanics that erupted along the flank of the dumanlidag volcano and comprise a thick rhyolitic pyroclastic sequence with small rhyolite domes and dykes in the uppermost parts the foca volcanics include sporadic occurrences of alkaline dykes and lavas this volcanic sequence interfingers laterally with lacustrine sedimentary rocks the volcanism was calc alkaline during the formation of the yuntdag volcanics and controlled by ne sw trending regional scale weakness zones along these fault or fracture zones three linearly aligned volcanic vents developed the volcanism was dominated by flank eruptions in the later stages and both subaerial and lacustrine volcano sedimentary deposits of the foca volcanics were formed during the latest phase volcanism was bimodal and alkaline trachyandesitic to phonolitic lavas and dykes coevally formed with the calc alkaline rhyolitic volcanics along ne sw trending fracture zones the flank of the dumanlidag volcano and extensive areas in western anatolia were covered by shallow lakes and widespread lacustrine limestones were deposited field studies and geochemical characteristics of the volcanic rocks indicate that the volcanism tectonic activity and the sedimentary deposition were progressive without any pronounced interruption and were controlled by nw se trending extension throughout the formation of the miocene succession

alkaline series related to early middle miocene intra continental rifting in a collision zone an example from polatli central anatolia turkey abstract a large volcanic area 7600 km2 the galatean volcanic province gvp developed in northwest central anatolia during the miocene along the neo tethys ocean suture zone possibly by post collisional processes the gvp mainly comprises 20 14 my old acid to intermediate volcanites with a geochemical signature indicating a mantle source modified by earlier late cretaceous subduction related events 100 km south of the gvp near polatli ankara basaltic rocks that cover large areas are intercalated with the miocene deposits of the beypazari basin an intra continental subsidence zone at the southwest of the gvp field observations geochemistry and k ar age dating of the polatli volcanites show that they are early 19 9 ma to mid 14 1 ma miocene in age covering an area as large as 215 km2 variations in lava thickness and the thickness of the underlying silicified baked zones suggest that the basaltic lavas erupted from a southern source possibly from the eskisehir fault zone and flowed northwards most polatli samples have chemical compositions that indicate derivation from a mantle source with crustal contamination during ascent they do not display any characteristic to suggest a subductional component although the gvp and polatli lavas formed close in time and space they were derived from different mantle sources considering the positions of these two magmatic regions with regard to the tethyan suture zone we propose that the mantle beneath the gvp and near the suture zone memorised the earlier subduction while the mantle beneath polatli that is located about 100 km further from the suture zone remained apparently unchanged after a significant volume of magma was consumed in the gvp a later 10 my and last activity guvem activity has produced quantitatively much less basaltic rocks where this subductional signature seems to completely disappear considering that the western anatolian crust is proposed to undergo extension since the late oligocene early miocene times the early miocene intra plate polatli activity may have developed within this extensional tectonic regime combined with regional data polatli data also provide broad estimations on how long a subductional event continues to modify the mantle after the subduction ceased at least 20 my how long the subductional signature is preserved during significant magmatism between 6 and 10 my and how far the subductional effect disappears laterally on the mantle with respect to the collision zone

analyses of fault mechanisms and expansion of southwestern anatolia since the late miocene abstract neotectonic field studies and detailed analyses of neogene and quaternary fault mechanisms in southwestern anatolia enable us to recognize a succession of compressional and extensional events and to characterize the direction of corresponding regional stresses the three most important compressive phases occurred during the miocene and a much smaller one near the plio quaternary boundary the last one or two interrupted a widespread extension of much greater duration and amplitude the whole tectonic evolution resembles that of the aegean the large extension by normal faulting is consistent with a minimum stress along a nne ssw average direction it appears that this direction was n s during the pliocene and changed to ne sw sometime during the quaternary this dominant nne ssw extension which began during late miocene or earliest pliocene was related to the development of the southwestern anatolian graben system

hudson bay hudson strait jokulhlaups and heinrich events a hypothesis abstract abrupt temperature changes in the northern north atlantic occurred frequently throughout the last glaciation as shown by proxy records from greenland ice cores deepsea cores and norway speleothems many of these variations occurred in irregular sawtooth cooling cycles which sometimes ended with the deposition of thick layers of ice rafted debris ird in the deep ocean that are known as heinrich events the lithologies of most of the ird deposits are consistent with widespread surges of the laurentide ice sheet that may have resulted from the accumulation of deformable sediments in portions of the ice sheet bed an alternative conceptual model proposed here to explain the sawtooth coolings and the surges involves repetitive jokulhlaups from a hudson bay lake dammed by ice at the mouth of hudson strait the slow sawtooth coolings may be explained by storm track diversion due to progressive coverage of the lake by icebergs and the surges by abrupt losses of water pressure and buttressing ice shelves at all ice sheet fronts in the lake when the ice dams failed

an example of an accretionary forearc basin from northern central anatolia and its implications for the history of subduction of neo tethys in turkey deformed sedimentary sequences of late cretaceous middle eocene age located between the sakarya continent and the anatolian complex have been interpreted as the fill of a forearc basin the history and structure of this basin are critical for understanding the evolution of the neo tethyan subduction in the middle east i test and elaborate upon this interpretation on the basis of three basic outcrop areas of upper cretaceous lower tertiary sedimentary sequences confined to a northeast southwest trending belt in north west ankara these are the alci kinik and orhaniye areas they expose two different sedimentary sequences called alci and orhaniye in the alci area the sequence starts at the base with the continental red clastic rocks on the erosional surface of an underlying ophiolitic melange and continues upward into the shallow marine reefal buildup of the late maastrichtian age the upper half of the alci sequence is separated from its lower half by a local disconformity and dominated by the continental debris flow deposits composed mostly of volcanic material by contrast both the kinik and orhaniye areas are characterized by a thick continuous and coarsening upward sequence overlying conformably the underlying ophiolitic melange the lower half of the orhaniye sequence is dominated by a deep marine flysch its middle part by continental clastic material and the topmost part by the shallow marine reefal buildup lower contact relationships lithologic composition facies distribution internal structures and the regional tectonic settings of both sequences strongly suggest that the above mentioned three outcrops preserve the remnants of a peripheral accretionary forearc basin forming the north northwestern margin of the haymana polath accretionary forearc basin during middle campanian middle eocene time this peripheral basin is here named orhaniye accretionary forearc basin

half graben filling processes in the early phase of continental rifting the miocene namurungule formation of the kenya rift abstract the miocene namurungule formation crops out on the eastern flank of the kenya rift representing basin fill that developed in association with miocene rifting the formation is characterized by large volumes of volcaniclastics supplied passively by pyroclastic fall facies analysis reveals that this formation consists mostly of lacustrine delta deposits with minor alluvial fan deposits at its base the conspicuous occurrence of a flood plain facies with infrequent channel fill deposits in the lower part of this formation suggest that the drainage area was limited in the early stage of deposition pyroclastic fall would therefore have been an important source of sediment during the early stages of rift development the delta deposits are divided into two distinct successions based on lithological characteristics separated by a thick pyroclastic layer in the middle part of the formation the stacking pattern of the lower succession is retrogradational whereas the upper succession is characterized by a pile of prograding bodies both delta successions are interpreted to have accumulated in an underfilled basin the change in depositional mode from the lower to upper is considered to be due to a change in the balance between the sedimentation rate and the rate of lake level rise assuming constant sediment supply the apparent difference in flooding scale between the lower and upper successions is attributed to the topographical widening of the basin flat similar successions also occur in another basin in the east african rift ngorora formation central kenya in which pyroclastic sediments are dominant and upward decrease in sedimentation rate is recognized the differing in the stacking patterns between the namurungule formation and the ngorora formation is probably induced by basin width the narrow namurungule basin seems to have been sensitive to increased sediment supply owing to the expansion of the catchment area

initiation of the neomagmatism in east anatolia abstract in eastern anatolia the neotectonic episode commenced with the complete elemination of the neo tethyan ocean floor as a result of collision between arabia and eurasia during early miocene time after the collision continuing convergence initiated a new tectonic regime and coeval magmatic activity the post collisional convergence caused crustal shortening and thickening as evidenced by regionwide development of e w trending folds and thrusts and conjugate strike slip faults the related volcanic activity has progressed in three cycles in the initial cycle weakly alkaline volcanic rocks were produced that are known as the solhan volcanics they outcrop at the western end of an e w striking neotectonic depression called the mus basin which constitutes the western prolongation of the lake van basin the basin is a thrust bounded depression that developed out of an original syncline by the disruption of its limbs the lavas of the first cycle reached the surface along n s aligned extensional structures in the second volcanic cycle a widespread k type ca volcanism occurred through crustal contribution during the late miocene early pliocene time when the continuing north south convergence caused substantial shortening and thickening of the continental crust the last volcanic cycle produced a thick volcanic cover consisting of rocks of alkaline affinity during the pleistocene and the quaternary when the thickened crust began to accommodate the ongoing north south shortening by east west extension after the formation of the east and north anatolian transform faults

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

comparison of young volcanic associations of western and eastern anatolia formed under a compressional regime a review abstract turkey is characterised by widespread post oligocene volcanism in western anatolia volcanic activity began during the late oligocene early miocene in a compressional regime a widespread suite of andesitic and dacitic calc alkaline rocks was erupted in this period they were accompanied by locally developed high level granitic intrusions the abrupt change from n s compression to n s stretching in the middle miocene was accompanied by a gradual transition to alkali basaltic volcanism in eastern anatolia the collision related compressional tectonics and associated volcanic activity began in the late miocene to pliocene and continued almost without interruption into historical times one minor and two major volcanic phases may be distinguished an initial minor eruptive phase of basic and intermediate alkaline rocks was followed by widespread eruptions of andesitic and dacitic calc alkaline rocks during the pliocene partly penecontemporaneous with this a second more important major phase of volcanism involving alkaline and transitional lavas began and continued during the quaternary the calc alkaline lavas of both regions were erupted at a time when the compressional regime led to crustal thickening these lavas display many geochemical and isotopic signatures that may be interpreted in terms of contamination of magma involving continental crustal materials the alkaline lavas in both regions began during the final stage of the compressional regime and form two groups one group is geochemically and isotopically similar to the calc alkaline rocks and the other is more typically alkaline the volcanic evolution of these two regions of turkey followed a somewhat similar pattern producing highly contaminated calc alkaline lavas at the beginning and evolving towards uncontaminated alkaline lavas at the end

segmented african lithosphere beneath the anatolian region inferred from teleseismic p wave tomography summary lithospheric deformation throughout anatolia a part of the alpine himalayan orogenic belt is controlled mainly by collision related tectonic escape of the anatolian plate and subduction roll back along the aegean subduction zone we study the deeper lithosphere and mantle structure of anatolia using teleseismic finite frequency p wave traveltime tomography we use data from several temporary and permanent seismic networks deployed in the region approximately 34 000 p wave relative traveltime residuals measured in multiple frequency bands are inverted using approximate finite frequency sensitivity kernels our tomograms reveal segmented fast seismic anomalies beneath anatolia that corresponds to the subducted portion of the african lithosphere along the cyprean and the aegean trenches we identify these anomalies as the subducted aegean and the cyprus slabs that are separated from each other by a gap as wide as 300 km beneath western anatolia this gap is occupied by slow velocity perturbations that we interpret as hot upwelling asthenosphere the eastern termination of the subducting african lithosphere is located near the transition from central anatolia to the eastern anatolian plateau or arabian eurasian collision front that is underlain by large volumes of hot underplating asthenosphere marked by slow velocity perturbations our tomograms also show fast velocity perturbations at shallow depths beneath northwestern anatolia that sharply terminates towards the south at the north anatolian fault zone nafz the associated velocity contrast across the nafz persists down to a depth of 100 150 km hence our study is the first to investigate and interpret the vertical extent of deformation along this nascent transform plate boundary overall the resolved upper mantle structure of anatolia is directly related with the geology and tectonic features observed at the surface of the anatolian plate and suggest that the segmented nature of the subducted african lithosphere plays an important role in the evolution of anatolia and distribution of its tectonic provinces

petrological and geochemical characteristics of cenozoic high k calc alkaline volcanism in konya central anatolia turkey abstract late miocene to pliocene volcanic rocks outcrop west northwest and southwest of the konya area in central anatolia turkey volcanic products are lava domes nuee ardentes and ignimbrite deposits predominantly andesitic to dasitic in composition together with rare basalt basaltic andesite basaltic trachyandesite and trachyandesite 50 35 69 39 sio2 the serie exhibits high k calc alkaline affinities fractional crystallization of pyroxene plagioclase and fe ti oxides is the main process in the magmatic evolution of konya volcanic rocks volcanic units exhibit typical high k calc alkaline character their geochemical characteristics e g enrichments in lil elements such as k rb ba sr depletion in hfse such as ti nb and high ba nb and low nb y ratios are consistent with those of active continental margin regions high 87 sr 86 sr 0 704841 0 707340 and low 143 nd 144 nd 0 512390 0 512618 ratios suggest crustal involvement in their petrogenesis correlations between 86 sr 87 sr isotope with rb rb nb rb ba and rb sr also emphasize the effect of crustal contamination on the andesitic and dacitic magmas as a consequence konya volcanic rocks are products of assimilation and fractional crystallization afc processes of a magma which seems to be linked to the subduction of the african plate underneath the anatolian plate during miocene

exhumation with a twist paleomagnetic constraints on the evolution of the menderes metamorphic core complex western turkey 1 much remains to be understood about the links between regional vertical axis rotations continental extension and shortening in western turkey miocene vertical axis rotations have been reported that occur simultaneously with the extensional exhumation of the menderes metamorphic core complex which has been related to back arc extension in the eastern part of the aegean back arc in this paper we explore the spatial and temporal relationships between vertical axis rotations in southwestern turkey and extensional unroofing of the menderes massif to this end we provide a large set of new paleomagnetic data from western turkey and integrate these with the regional structural evolution to test the causes and consequences of oroclinal bending in the aegean region the lycian nappes and bey daglari are shown to rotate 20 between 16 and 5 ma defining the eastern limb of the aegean orocline this occurred contemporaneously with the exhumation of the central menderes massif along extensional detachments and after the latest oligocene to early miocene exhumation of the northern and southern menderes massifs exhumation of the latter two was not associated with vertical axis rotations the lower miocene volcanics in the region from lesbos to usak to the north of the central menderes massif underwent a small clockwise rotation insignificant with respect to eurasia this shows that exhumation of the central menderes massif was associated with a vertical axis rotation difference between the northern and southern menderes massifs of 25 30 this result is in excellent agreement with the angle defined by the trends of buyuk menderes and alasehir detachments as well as the angle defined by the regionally curving stretching lineation pattern across the central menderes massif these structures define a pivot point rotation pole for the west anatolian rotations the rotation of the southern domain including the southern menderes massif the lycian nappes and bey daglari must have led to n s contraction east of this pole the eastern limit of the rotating domain is formed by the transpressional couple of the aksu thrust and kirkkavak fault in the center of the isparta angle previously reported clockwise rotations in the volcanic fields near afyon may be the result of distributed n s shortening east of the pivot point the precise accommodation of this shortening history remains open for investigation late oligocene to early miocene extension in the eastern part of the aegean back arc was ne sw oriented and likely bounded by a discrete transform this transform may be associated with an early evolution of the eastern aegean subduction transform edge propagator fault oroclinal bending in the west anatolian region is likely related to a reconnection of the eastern part of the aegean orocline with the african northward moving plate in tandem with roll back in the aegean back arc comparable to a recently postulated scenario for western greece

epicontinental permian cretaceous seaways in central india the debate for the narmada versus godavari rifts for the cretaceous tertiary incursion abstract this study presents an overview of mesozoic transgressions that influenced the palaeogeography of central india and offers an analysis of the existing evidence for the interpretation of the depositional record of infra and inter trappean sequences these data are then used to understand the respective palaeogeographic settings of the narmada and the godavari master valleys leading to a reappraisal of the paths suggested thus far for a cretaceous tertiary k t seaway major rift related discontinuities have been subjected to reactivation episodes during the mesozoic these tectonic events caused the initiation of several pericratonic basins the riftogenic valley systems have been affected by transgressions from the western margin of india through the narmada valley and or from the eastern margin through the godavari valley however for the most part these continent scale valley systems have hosted mainly mesozoic fluviatile and lacustrine sediment successions besides a marine incursion from the west in the lower reaches of narmada valley is widely recognised on the basis of the late cretaceous bagh beds additionally the maastrichtian palaeogeography of these valley systems of central india have been strongly influenced by the uplift resulting from the thermo magmatic flux associated with the deccan volcanism this resulted in major topographic readjustments within the godavari and narmada tapti palaeovalleys resulting in turn in major basinal depressions as revealed from the reconstruction of the palaeo digital elevation model significantly removed from the eastern and western coastal margins of india isolated occurrences of marine biota such as foraminifera marine algae and palm fossils have been found in infra and inter trappean maastrichtian and danian sequences of central india their presence in these inland basins is enigmatic and three hypotheses have been proposed to explain the presence of marine environments in these basins a trans deccan strait connecting both the margins of india through pre existing rift systems b an 800 km long seaway through the narmada valley and c a marine incursion through the godavari valley this palaeogeographic analysis supports a marine incursion through the godavari rift and presents arguments against the other two

large scale architecture in non marine basins the response to the interplay between accommodation space and sediment supply sedimentary successions of non marine basins can be considered in terms of accommodation space and sedimentary supply changes changes in accommodation space controlling the large scale architecture of non marine basins are different in areas with high and low sedimentary supplies uplift of intrabasinal monoclines and anticlines reduced the available accommodation space resulting in changes in both the geometry of the depositional sequences and the large scale architecture of fluvial mudflat and shallow carbonate lacustrine deposits main drainage fluvial systems record areas with a high sedimentary supply while mudflats and shallow fluctuating lakes represent areas that received less sediment two end members in the large scale architecture of main drainage fluvial system in the almazan basin spain are i ribbon shaped channel fills with low interconnectivity which pass laterally into mudflats dominated by mudstones and evaporites and into palustrine and shallow carbonate lacustrine deposits mainly in the a2 depositional sequence and ii sheet like channel fills with high interconnectivity laterally correlated with stacked calcretes in the marginal mudflats in the upper part of a3 ribbon shaped channel fills formed in areas of high accommodation space and sheet like channel fills formed in areas of reduced accommodation space

neotectonic deformation in the western sector of tectonic escape in anatolia palaeomagnetic study of the afyon region central turkey abstract following final closure of the neotethyan ocean during the late miocene deformation in central turkey has led to crustal thickening and uplift to produce the anatolian plateau followed by westward extrusion of terranes by strike slip widespread volcanism has accompanied this latter neotectonic phase and palaeomagnetic study of the volcanism shows a coherent record of differential block rotations indicating that the anatolian region is not a plate or platelet sensu stricto but is undergoing distributed internal deformation to evaluate the scale of neotectonic rotations in the transition zone near the western limit of tectonic escape and the border of the extensional domain in central west turkey we have studied the palaeomagnetism at 82 sites in volcanic suites distributed along a 140 km lineament with north south trend and ranging in age from 18 to 8 ma comparable deflection of magnetic remanence from the present field direction is identified along the full length of the lineament a mean clockwise rotation of 12 3 4 2 is determined for this western sector of the anatolian strike slip province since similar rotations are observed in the youngest and oldest units this cumulative rotation occurred after the late miocene when interpreted together with results elsewhere in anatolia it is inferred that the rotation is later than crustal thickening and uplift of the anatolian plateau and entirely a facet of the tectonic escape inclinations are mostly 10 shallower than the predicted miocene field and are considered to reflect the presence of a persistent inclination anomaly in the mediterranean region larger rotations departing from the regional trend are also observed within the study region but are confined to the vicinity of major faults notably those bounding the afyon aksehir graben the pattern of neotectonic declinations across anatolia identifies strong anticlockwise rotation in the east near the arabian pincer with progressive reduction in the amount of rotation towards the west it becomes zero or slightly clockwise at the western extremity of the accreted terrane collage rotations also appear 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 the westward radial expansion of the extruded terranes is inferred to combine with backroll on the hellenic arc to produce the contemporary extensional province in western turkey

quaternary geology of eastern germany saxony saxon anhalt south brandenburg thuringia type area of the elsterian and saalian stages in europe abstract the characteristic feature of the quaternary geology of eastern germany location map fig 1 is a sequence of more than 50 horizons and complexes of glacial laminated clays tills glaciofluvial sediments and periglacial river gravels gelifluction sheets alluvium loess facies in the period between the younger tertiary and the first elsterian continental glaciation at least four gravel terraces were built up under cold climate conditions the youngest of these gravel bodies lacks scandinavian rocks and is interbedded with elsterian glaciolacustrine deposits pre elsterian temperate periods have been recorded at a number of places i e zeuchfeld untermassfeld voigtstedt sussenborn two major ice advances with additional minor oscillations have been identified of elsterian and saalian ages complete eemian and holsteinian sequences are represented showing vegetational development through each interglacial cycle cool temperate warm cool the weichselian glacial stage in eastern germany is represented by thick periglacial sedimentation including gravels gelifluction sheets alluvium debris covers and loess within these sediments is a wide variety of glaciotectonic structures and periglacial soil structures including classical involutions and ice wedge casts an outline of the present state of knowledge of the quaternary of eastern germany is given in tables 1 3 while table 4 presents a stratigraphical comparison with the neighbouring regions and countries the palaeogeography of the region during the periods of the european continental glaciation is depicted in fig 2

tertiary geology of the saale elbe region abstract the lowlands around leipzig and the adjoining region between the river saale and river elbe were a low subsiding basin from the middle eocene to the middle miocene that merged with the tertiary basin of northern germany in the middle oligocene in addition to epirogenic subsidence subrosive solution lowering resulted in complicated patterns of sedimentation solution along individual beds has resulted in enormous variations in the thickness of lignite in areas such as geiseltal the weisse elster basin and in the lutzen merseburg and duben torgau graben fluvial fluvial limnic and organic sediments interbed with marine and marine littoral facies and four marine transgressions can be identified in the upper eocene and lower miocene during the middle oligocene the marine transgression reached its maximum extent in eastern germany during the period between the middle and upper oligocene uplift of the area resulted in subaerial erosion and valley like dissection of the older tertiary strata from the upper miocene through to the pliocene erosion has been dominant

petrogenesis and 40ar 39ar geochronology of the volcanic rocks of the usak gure basin western turkiye abstract in spite of much research over the past 30 years the dynamic evolution origin of the volcanism and geometrical stratigraphical relations of the ne sw trending basins in western anatolia are poorly understood the usak gure basin is one of the prominent ne sw trending basins developed on the northern part of the menderes massif core complex three distinct volcanic successions are found in the usak gure basin 1 the beydagi volcanic unit composed of shoshonite latites and rhyolitic lavas followed by dacitic and andesitic pyroclastic deposits 2 the payamtepe volcanic unit composed of potassic intermediate composition lavas latites and trachytes and 3 the karaagac dikes composed of andesite and latite the beydagi volcanic unit occurs in three different ne sw trending volcanic centers beydagi itecektepe and elmadag calderas from southwest to northeast respectively the oldest radiometric ages for the beydagi volcanic unit are from the elmadag volcanic center in the north and range from 17 to 16 ma the data indicate that volcanism was active during the latest early miocene the youngest radiometric age for the beydagi volcanic unit is obtained from the beydagi caldera located 12 ma in the south the data indicate that beydagi volcanism was active in the late middle miocene and migrated from north to south with time 40ar 39ar ages of the payamtepe volcanic unit are restricted to a short period between 16 0 and 15 9 ma volcanic rocks of the usak gure basin are characterized by strong enrichment in lile and lree and depletions of nb ta and ti on morb normalized multi element diagrams geochemical features of the volcanic rocks suggest that they experienced mixing processes between mafic and felsic end members and also fractional crystallization of dominantly plagioclase and pyroxenes from mixed magma compositions crustal contributions to the magma sources may also have occurred during magmatic evolution these processes have resulted in scattered major and trace element variations with respect to increasing silica contents geochemical features of the most mafic samples agree with the results of previous studies from other volcanic areas in western anatolia suggesting that the volcanic rocks in the region were derived from a mainly lithospheric mantle source that had been heterogeneously metasomatized by previous subduction events during convergence between the african and eurasia plates the volcanic activity in the region which developed synchronously with the formation of the menderes massif core complex is best explained by delamination of lithospheric mantle slices that were heterogeneously enriched by previous subduction related processes

calcic paleosols of the plio pleistocene camp rice and palomas formations southern rio grande rift usa abstract seventy four separate paleosols are recognized in the plio pleistocene camp rice and palomas formations of the southern rio grande rift seven types of profiles are present a bw bk c a bt bk c bw bk c bt bk c bt k c bk c and ak calcic and petrocalcic horizons bk and k commonly overlain by argillic horizons bt dominate most paleosol profiles greater pore size and enhanced permeability typical of sandy and silty parent material favored the development of argillic horizons however micrite is the dominant form of calcium carbonate in bk and k horizons regardless of parent material grain size non calcified a horizons are typically lighter in color than adjacent subsurface pedogenic intervals due to their oxidized nature or lower clay content they are only rarely preserved probably due to erosion prior to final burial calcified root mats ak are not directly associated with other pedogenic horizons abundant horizontal roots suggest root mats formed under high water table conditions restriction of ak horizons to the distal piedmont lithofacies supports their development as spring or pond deposits near the toes of alluvial fans individual pedogenic horizons can often be traced hundreds of meters to kilometers normal and parallel to a basin s axis paleosol maturity and preservation potential are greatest for symmetrical basins especially where pedogenesis was far removed from active channels within the axial fluvial system or within distal piedmont settings of asymmetrical basins

stable climate in india during deccan volcanism suggests limited influence on k pg extinction abstract large igneous provinces lips have been temporally correlated to mass extinctions throughout the phanerozoic including the emplacement of the deccan volcanic province dvp 66 3 65 6 ma in western and central india which has been invoked as either a cause or exacerbating factor in the cretaceous paleogene k pg extinction however relatively little is known about local paleoclimatic and paleoenvironmental responses to volcanism to investigate the dvp s role as a driver of local environmental change and to provide climatic background for known ecological shifts new inter basaltic paleosol profiles at the eastern edge of the dvp are used in conjunction with profiles from the literature to reconstruct paleoclimate and terrestrial environments before and after the k pg these profiles provide a novel opportunity to study the sediments within basalt flows before during and after a mass extinction event and in the midst of a lip emplacement event paleoclimate proxies and the floral humidity province proxy reflect little long term change in either climate or environment across the k pg with stable precipitation values and temperatures accompanied by a constant forest signal these interpretations are corroborated by macrofloral records and sedimentology from india which suggest some environmental turnover but generally support a forested fluvio lacustrine environment throughout the duration of volcanism our results support the possibility of rapid recovery times for terrestrial ecosystems during volcanism and suggest that while dvp eruptions may have exacerbated long term environmental perturbation the emplacement of the dvp is not likely to have caused the terrestrial mass extinction at the k pg boundary

a quantitative approach to soil occurrence in alluvial deposits and its application to the old red sandstone of britain palaeosols fossil soils are a major component of alluvial deposits in the geological record not only do these typically show considerable variations in their degrees of development within single formations but they also exhibit highly complex stratigraphic relationships with one another a simple quantitative approach to these variations is presented which provides a graphical means of assessing differences in soil palaeosol development within a sequence with calcic or petrocalcic horizons to illustrate the approach a range of palaeosols from the siluro devonian old red sandstone of britain are characterized in terms of the likely frequency and magnitude of depositional events which occurred during their formation in particular two alluvial suites from the manorbier area of south wales are analysed using this approach the technique should be widely applicable to other alluvial successions and provides a means of graphicallv presenting relationships between multiple palaeosols although the wide range of rates of formation of calcic and petrocalcic horizons precludes their use to provide narrow estimates of deposition rates

early miocene to quaternary evolution of volcanism and the basin formation in western anatolia a review abstract western anatolia largely affected by extensional tectonics witnessed widespread volcanic activity since the early miocene the volcanic vents of the region are represented by epicontinental calderas stratovolcanoes and monogenetic vents which are associated with small scale intrusions as sills and dykes the volcanic activity began with an explosive character producing a large ignimbritic plateau all over the region indicating the initiation of the crustal extension event these rhyolitic magmas are nearly contemporaneous with granitic intrusions in western anatolia the ignimbrites emplaced approximately contemporaneous with alluvial fan and braided river deposits flowed over the basement rocks prior to extensional basin formation the lacustrine deposits overlie the ignimbrites the potassic and ultrapotassic lavas with lamprophyric affinities were emplaced during the late miocene pliocene the volcanic activities have continued with alkali basalts during the quaternary

lithofacies associations and stable isotopes of palustrine and calcrete carbonates examples from an indian maastrichtian regolith detailed information on semi arid palustrine carbonate calcrete lithofacies associations in a sheetwash dominated regolith setting is sparse this is addressed by studying the lower limestone of the lameta beds a well exposed maastrichtian regolith in central india the general vertical lithofacies assemblage for this unit comprises a basal calcareous siltstones and marls with charophytes ostracods and gastropods b buff micritic limestones associated in their upper parts with calcretized fissure fill sandstones c sheetwash as fissure fill diamictites and thin pebbly sheets locally developed over a few metres and d sandy nodular brecciated and pisolitic calcretes at the top the sequence is regressive with upsection filling of topographic lows by increased sheetwash lateral lithofacies change is marked but there are no permanent open water lake deposits in topographic lows close to the water table marshy palustrine or groundwater calcretes formed whereas on better drained highs brecciation and calcretization occurred prolonged exposure is implied suggesting that shrinkage was the main cause of brecciation evidence for rhizobrecciation and other biological calcrete fabrics is sparse contrasting with the emphasis on root related brecciation in many studies of palustrine lithofacies stable isotope d18o and d13c values are consistent with the palustrine limestones being fed from meteoric derived groundwater with a strong input of soil zone carbon there is overlap of both d18o and d13c values from the various palustrine and calcrete fabrics co occurring at outcrop this suggests that in groundwater supported wetlands conversion from palustrine carbonate to calcrete need not show isotopic expression as the groundwater source and input of soil zone carbon are essentially unchanged cretaceous tertiary d18o and d13c values from palustrine lithofacies and associated calcretes appear to be strongly influenced by the inherited values from lakes and wetlands hydrologically closed lakes and marine influenced water bodies tend to result in low negative palustrine d18o and d13c values during brecciation and calcretization the degree of isotopic inheritance depends on whether or not alteration occurs in waters that are different from those of the original water body or wetland marked biological activity e g rhizobrecciation or root mat development during calcretization may lower d13c values where c3 plants are abundant but in shrinkage dominated systems d13c values will be largely inherited from the palustrine limestones

a mesozoic time scale we present an integrated geomagnetic polarity and stratigraphic time scale for the triassic jurassic and cretaceous periods of the mesozoic era with age estimates and uncertainty limits for stage boundaries the time scale uses a suite of 324 radiomenc dates including high resolution 40 ar 39 ar age estimates this framework involves the observed ties between 1 radiometric dates biozones and stage boundaries and 2 between biozones and magnetic reversals on the seafloor and in sediments interpolation techniques include maximum likelihood estimation smoothing cubic spline fitting and magnetochronology

palaeontological and sedimentological observations on nonmarine lameta formation upper cretaceous of maharashtra india their palaeoecological and palaeoenvironmental significance abstract the lameta formation upper cretaceous is exposed in parts of central and western india as detached outcrops and covers an area of nearly 5000 km 2 it generally rests on precambrian and gondwana rocks and is invariably capped by deccan trap volcanic flows in the nand and dongargaon areas of the chandrapur and nagpur districts of maharashtra the lameta formation covers more than 400 km 2 attains a thickness of 20 m and is richly fossiliferous the palaeontological and sedimentological observations strongly indicate alluvial limnic environment for the deposition of the lameta sediments under semi arid conditions different lithofacies representing channel overbank paludal and lacustrine subenvironments have been identified the biota represents terrestrial semiaquatic and aquatic communities and is represented by dinosaurs fishes crocodiles chelonia gastropods ostracodes charophytes coniferales and angiosperms the biota appears to be mainly controlled by the different lithofacies thereby suggesting strong palaeoecological and taphonomical control over their occurrence records of mass death of clupeids have been observed in many layers within the lacustrine clays a nesting site of sauropods has been found near pavna along with evidence of site fidelity a clutch with small oblong shaped eggs of avian like affinity has been also unearthed from this nesting site the lameta sediments were deposited in a freshwater environment that provided the preferred ecological niche for large scale breeding and nesting of sauropods

application of confocal laser scanning microscopy clsm to autofluorescent organic and mineral matter in peat coals and siliciclastic sedimentary rocks a qualitative approach abstract organic matter occurring in the form of macerals and natural solid bitumens in peats coals and siliciclastic sediments of various stratigraphic ages and locations was studied by means of conventional incident light microscopy and clsm classical optical microscopic investigations are restricted by conventional 2 d imaging and are often hindered by the associated out of focus blur effects the qualitative application of clsm overcomes these limitations permitting to reveal precisely 3 d morphology and detailed microstructure of autofluorescent organic matter the in depth examinations along z axis in xy xz or yz scanning modes at increments of 250 nm are capable to reconstruct 3 d internal configuration and arrangement occurring in autofluorescent macerals the non invasive and non destructive laser raster technique is applied to characterize in situ autofluorescent organic particles at micron to sub micron scale resolution in polished whole rock pellets in this study we demonstrate that clsm is suitable to i detect fine scale microstructure of autofluorescent organic matter iii reconstruct 3 d morphology at cellular and tissue level iii analyze maceral composition in terms of its relicts and fragments beyond the classical optical assignment limits iv detect and examine inorganic components enclosed in the embedding mineral bituminous groundmass and v differentiate mineral constituents from the remaining organic matter clsm as an optical microscopic technique was applied to generate high resolution 2 d and 3 d images projections as well as 3 d reconstructions of autofluorescent objects excited with aid of laser induced light operating at variable visible wavelengths clsm is applicable to support microscopic studies of thermally immature and mature organic matter within the oil and early gas windows enclosed either within siliciclastic and carbonate sediments or in peat and low to medium rank coals the application of this technique will be of great interest to a wide range of geology related disciplines such as petroleum geology biostratigraphy marine geology peat petrography and archeology

co2 levels in the late palaeozoic and mesozoic atmosphere from soil carbonate and organic matter satpura basin central india abstract a number of calcic palaeosols have been identified within the fluvial deposits of the motur permian the denwa triassic the bagra jurassic and the lameta cretaceous formations of the satpura sedimentary succession central india these palaeosols show accumulation of pedogenic carbonates in rhizocretions and glaebules the carbon isotopic compositions of these carbonates and the coexisting soil organic matters are used to determine the isotopic composition and the partial pressure of atmospheric co 2 using the co 2 palaeobarometer developed by cerling am j sci 291 1991 377 it is seen that the atmospheric co 2 level increased by a factor of 8 from the permian to the jurassic and declined again during the cretaceous the nature of the changes agrees with the result of the co 2 evolution model of berner geocarb ii but the magnitude of the co 2 increase in the middle jurassic and the late cretaceous was higher than the predicted value degassing of earth s interior due to rapid break up of the gondwana landmass during the triassic and jurassic period could have caused the rapid co 2 increase

palaeoenvironments of the dinosaur bearing lameta beds maastrichtian narmada valley central india abstract the maastrichtian lameta beds of central india are intimately associated with the deccan lavas and are critical to determining upper cretaceous palaeoenvironments and palaeogeography of the area in the type jabalpur sub region four mappable units of the lameta beds are recognised the basal green sandstone is interpreted as a braided stream deposit the lower limestone characterised by brecciation and shrinkage cracks is interpreted as a sub aerially exposed palustrine flat with calcrete formation occurring on topographic highs of low relief plains the overlying mottled nodular beds exhibit a variable range of calcrete fabrics and morphologies including circum granular and linear cracks root casts and nodules these are interpreted as pedogenically modified sheet wash deposits of a semiarid alluvial plain the upper sandstone is a sheet flood deposit again pedogenically modified before arrival of the basal lava flows overall the lameta beds are considered to represent a regionally extensive maastrichtian regolith carbon and oxygen isotope analyses of calcareous components are entirely consistent with soil zone environments the 13c values are low typically 8 to 9 pdb demonstrating a strong input of carbon from the decay of terrestrial land plants calcrete 18o values are variable 5 to 10 pdb consistent with precipitation from meteoric water some of which was evaporatively modified in pools on the alluvial palustrine flat the lameta beds are well known for sauropod nesting sites and sedimentological analyses of these sites suggest that the animals selected topographic highs usually in marly or sandy soft sediment multiple nests with similar egg types probably indicate colonial nesting isotopic analyses of eggshell carbonate agree with earlier work suggesting that the sauropods ate a c3 plant food

geology and petrology of the simav magmatic complex nw anatolia and its comparison with the oligo miocene granitoids in nw anatolia implications on tertiary tectonic evolution of the region the oligo miocene granitic plutons and their related volcanic subvolcanic successions form a nw se trending magmatic belt along the northern border of the menderes massif this belt evolved within a nappe package consisting of the menderes metamorphics sakarya continent afyon zone and tavsanli zone and also intruded this nappe package the ezine evciler eybek kozak alacam koyunoba egrigoz and the baklan plutons emplaced along this belt and show similarities in their internal structures emplacement mechanisms and petrological characteristics these different granitic plutons cut and stitch various combinations of the nappe package of the above mentioned tectonic belts and evolved during and following the alpine collision they all show characteristic map patterns of shallow seated plutons and range from granite to monzogranite the granitic plutons display calc alkaline i type and post collisional geochemical characteristics the egrigoz koyunoba plutons and their subvolcanic volcanic phases simav magmatic complex were studied in detail the geochemical characteristics and field occurences of the simav magmatic complex were compared to the other magmatic associations in western anatolia and it was determined that it is of collisional origin and not related to an extensional tectonic regime as suggested in some recent studies

composite volcanoes in the south eastern part of izmir balikesir transfer zone western anatolia turkey abstract during the early middle miocene western anatolia several volcanic fields occur along a ne sw trending shear zone known as izmir balikesir transfer zone this is a deformed crustal scale sinistral strike slip fault zone crossing the bornova flysch and extending along the nw boundary of the menderes massif by accommodating the differential deformation between the cycladic and menderes core complexes within the aegean extensional system here we discuss the volcanic activity in yamanlar and yuntdagi fields that is closely related to the extensional tectonics of the izmir balikesir transfer zone and in the same time with the episodic core complex denudation of the menderes massif this study documents two composite volcanoes yamanlar and yuntdagi whose present vent area is strongly eroded and cut by a variety of strike slip and normal fault systems the transcurrent nw se being the dominant one the erosional remnants of the vent areas resembling a shallow crater intrusive complex illustrate the presence of numerous dykes or variably sized neck like intrusions and lava flows typically associated with hydrothermal alteration processes propylitic and argillic such vent areas were observed in both the examined volcanic fields having 6 km in diameter and being much more eroded toward the south along the nw se fault system lava flows and lava domes are sometimes associated with proximal block and ash flow deposits in the cone building association part besides lava flows and remnants of lava domes rare block and ash and pumice rich pyroclastic flow deposits as well as a series of debris flow deposits have been observed the rocks display a porphyritic texture and contain various proportions of plagioclase clinopyroxene orthopyroxene amphibole rare biotite and corroded quartz the examined rocks fall at the limit between calc alkaline to alkaline field and plot predominantly in high k andesite and dacite fields and one is rhyolite the trace element distribution suggests fractional crystallization processes and mixing in upper crustal magma chambers and suggests a metasomatized lithospheric mantle lower crust source this preliminary volcanological petrological and geochronological base study allowed documenting the yamanlar and yuntdagi as composite volcanoes generated during post collisional early middle miocene transtensional tectonic movements

tomographic pn velocity and anisotropy structure beneath the anatolian plateau eastern turkey and the surrounding regions an edited version of this paper was published by the american geophysical union agu copyright 2003 agu see also http www agu org pubs crossref 2003 2003gl017391 shtml http atlas geo cornell edu turkey publications al lazki et al 2003 htm

coeval plutonism and metamorphism in a latest oligocene metamorphic core complex in northwest turkey a metamorphic core complex of latest oligocene age crops out in the kazdag mountain range in northwest turkey the footwall of the core complex consists of gneiss amphibolite and marble metamorphosed at 5 1 kbar and 640 50 c the average muscovite and biotite rb sr ages from the gneisses are 19 ma and 22 ma respectively and imply high temperature metamorphism during latest oligocene times the hangingwall is made up of an unmetamorphosed lower tertiary oceanic accretionary melange with upper cretaceous eclogite lenses the hangingwall and footwall are separated by an extensional ductile shear zone two kilometres thick mylonites and underlying high grade metamorphic rocks show a n trending mineral lineation with the structural fabrics indicat ing down dip top to the north shear sense the shear zone the accretionary melange and the high grade metamorphic rocks are cut by an undeformed granitoid with a 21 ma rb sr biotite age analytically indistinguishable from the rb sr biotite ages in the surrounding footwall gneisses the estimated pressure of the metamorphism and that of the granitoid emplacement indicate that the high grade metamorphic rocks were rapidly exhumed at 24 ma from a depth of 14 km to 7 km by activity along the shear zone the subsequent exhumation of the metamorphic rocks to the surface occurred during pliocene quaternary times in a transpressive ridge between two overstepping fault segments of the north anatolian fault zone the high grade metamorphic rocks of the kazdag range are surrounded by voluminous calc alkaline volcanic and plutonic rocks of late oligocene early miocene age which formed above the northward dipping hellenic subduction zone the magmatic arc setting of the core complex and stratigraphic evidence for subdued topography in northwest turkey prior to the onset of extension suggest that the latest oligocene regional extension was primarily related to the roll back of the subduction zone rather than to the gravitational collapse

the mount kozak magmatic complex western anatolia abstract the mount kozak igneous complex is located close to the towns of ayvalik bergama and burhaniye in the western anatolia turkey magmatic activity occurred during the late oligocene early miocene beginning with the emplacement of the kozak pluton sheet intrusive rocks formed around it coevally they are surrounded by the volcanic rocks partly contemporaneously with the emplacement of the granitic rocks during the early miocene the upper oligocene lower miocene magmatic rocks of the kozak region are represented by a high k calc alkaline suite of predominantly intermediate and acidic composition their geochemical characteristics suggest that the magmas are hybrid and were formed from a similar source representing mantle derived magmas contaminated by crustal materials the cogenetic plutonic rocks the hypabyssal rocks and the overlying volcanic associations are related to one another in space and time and appear to have been connected to a shallow level granitic intrusion in a caldera collapse setting the calc alkaline magmatic activity waned during the middle miocene when the volcanism was rejuvenated during the late miocene pliocene alkaline basalt lavas were formed as fissure eruptions

shrinkage and sediment supply control on multiple calcrete profile development a case study from the maastrichtian of central india multiple calcrete profiles of the mottled nodular beds form part of an extensive dinosaur bearing infratrappean regolith in central india the profiles have clear variations in the distribution of carbonate morphologies powdery nodular and sheet platy calcretes sheet calcrete is however distinctive and resembles to some extent a k horizon these calcretes are interpreted as having formed in the soil vadose zone profile development was governed mainly by the pattern and depth of shrinkage it is possible that the mature stage 3 to incipient stage 4 calcrete sheets of these shrinkage related profiles formed quite rapidly and certainly in no more than about 400 000 years prominent shrinkage cracking appears to have favoured quite rapid calcrete formation and associated rhizocretion formation was also likely to have been rapid a combination of climatic conditions carbonate availability and volcanism induced sediment starved conditions resulted in the development of a stack of fourteen calcrete profiles sediment starvation allowed most of the stratigraphic interval to be affected to some degree by calcareous pedogenesis this contrasts with other phanerozoic calcrete stacks where nodular carbonate typically occurs in discrete horizons caused by relatively higher sediment supply

implications of the infra and inter trappean biota from the deccan india for the role of volcanism in cretaceous tertiary boundary extinctions the fossil record shows a remarkable similarity between the biota that existed before and after the initiation of deccan volcanic activity virtually all the available palaeontological evidence such as the fauna and flora of the freshwater infra and inter trappean beds and the planktonic foraminifera from the subsurface infra and inter trappean beds of the southeastern coast do not favour the initiation of deccan volcanism as the cause of mass extinctions at the cretaceous tertiary k t boundary instead a combination of events such as an extended period of volcanism changes in sea level and related climatic changes and certain local factors may have played a significant role in selectively eliminating various groups of organisms this view is further reinforced by the biotic changes across the k t iridium layer in the um sohryngkew river section of meghalaya northeastern india

tertiary and quaternary volcanism of the erzurumkars area eastern turkey geochronological data and geodynamic evolution abstract this paper presents new geochemical and geochronological data on the neogene and quaternary volcanic products from the area of erzurum and kars eastern turkey the affinity of most of the volcanic rocks concerned is calc alkaline with the exception of minor quaternary alkaline rocks that outcrop in the kars sector ages range from 8 m y to 1 3 m y the time space distribution of the calc alkaline volcanism in eastern turkey nw iran is characterized by a sudden northward jump that occurred around 6 m y ago from the van erzurum southern belt to the kars northern belt available data indicate that this northward migration of volcanism was due to changes in the subduction geometry of the arabian plate under eurasia

alluvial geoarchaeology of a small drainage basin in western anatolia late holocene landscape development and the question of the mouth of the paleo bakircay abstract late holocene landscape evolution in the geyikli basin a sub catchment of the bakircay basin on the west anatolian coast and its implications for the plaeogeography of the environs of ancient pergamon modern bergama were studied by a combination of archaeological and geographical investigations the study aims to investigate whether the dorpfeld scenario of the paleogeographical situation in the lower bakircay valley is true or not the scenario postulates that during the late holocene an alluvial fan fed from the geyikli valley progressively closed a topographical constriction between the aegean sea and a supposed paleo gulf that occupied the lower bakircay valley initially this caused the development of an inland lake and finally the shift of the mouth of the paleo bakircay from a northern position to its modern southern position the lithostratigraphy of four sediment outcrops in the lower geyikli basin and in the topographical constriction between the aegean coastal plain and the bakircay valley shows that during the past ca 1950 years the lower geyikli valley was inhabited by a braided river with a highly dynamic depositional system sedimentation totalled about 4 6 m in the past 1950 years indicating a drowning of the landscape in terrestrial sediments in recent times gravel mining has led to a deformation of the valley floor and the geyikli s fluvial terrace has become inactive the lack of any sediment related to a paleo gulf or a paleo lake inside the bakircay basin as well as the lack of any sediments of a northern paleo bakircay documents that the dorpfeld scenario does not apply for the past 1950 years archaeological findings show that the geyikli basin was intensively settled in historic times but there is no evidence that the geyikli basin was anthropogenically deformed in a way that could have contributed to the dorpfeld scenario

palaeosols as indicators of geomorphic stability in two old red sandstone alluvial suites south wales palaeosols fossil soils are abundant in the alluvial late silurian early devonian moor cliffs formation and rat island mudstone freshwater west formation of south dyfed south wales the palaeosols occur in thick mudstones deposited on floodplains under a seasonal semi arid climate and represent vertisol type soils simple single profiles are rare and most of the mudstone intervals exhibit complex overprinted profiles however a major difference exists between the palaeo vertisols in each of the two units studied the moor cliffs formation contains thick floodplain intervals with evidence of frequent erosion and reactivation of earlier soil horizons the associated coarser channel deposits mainly represent ephemeral streams the alluvial system was unstable flashy and prone to extensive stripping of stored floodplain sediment arroyos unstable ephemeral stream channels probably developed during this interval evidence for any marine influence on soil development is missing and previous speculations that the formation may represent deposition in an upper intertidal or supratidal system are not supported the rat island mudstone represents a complete contrast in that there was little or no stripping of floodplain sediments the channel deposits are typically of the fining upwards type representing more stable low sinuosity channels and with ephemeral stream floods by integrating the palaeosols a more detailed picture of the geomorphic history of these units can be formulated comparison with contemporary drainage basins indicates that a change in climate was a possible cause for the differences between the two units less frequent and more severe storms occurring during the deposition of the rat island mudstone

timing of tectonic events in the menderes massif western turkey implications for tectonic evolution and evidence for pan african basement in turkey the menderes massif forms the western of the two large metamorphic culminations within the turkish alpide orogen it has three major lithologic units with a gneissic core at the base and a schist and a marble envelope overlying it successively although relations between them have been largely obscured by the polymetamorphic and structurally complex history of the massif we present a review of the available stratigraphic evidence and combine it with new isotopic ages from the central and southern parts of the massif to constrain the timing of major tectonic events that shaped the massif since the late proterozoic pt3 in the southern part of the massif sensu stricto three episodes of deformation and metamorphism are distinguished whereas in its northern part there are four the first episode occurred at 500 10 ma with intense deformation and metamorphism at high grade amphibolite facies with local anatexis in the central part of the massif the 470 9 ma old now highly deformed tonalitic and granitic intrusions mark the end of this episode on a cambrian reconstruction of continents around the eastern mediterranean the menderes massif forms the southern end of the pan african orogenic collage of northeastern africa and arabia the area of earliest palaeozoic deformation in the menderes may connect with the northwest african orogenic collage along the strike via the bozburun and saricicek diabases arkoses and schists in the center of the karacahisar dome interpreted herein as fragments of a pan african suture the earliest palaeozoic deformations to affect the rocks were probably related to the last pan african collisions and associated postcollisional convergence the southern part of the massif was undeformed from early ordovician to the early later eocene whereas the northern part was deformed metamorphosed and intruded possibly during the late triassic related to the closure of the karakaya marginal basin of palaeo tethys the next major event affecting the whole of the massif was the intense deformation and widespread metamorphism that reached high amphibolite grade in the structurally lower parts and only greenschist grade in the outermost envelope this metamorphism here called the main menderes metamorphism mmm is biostratigraphically constrained between early eocene and early oligocene time rb sr isotopic data show a spread of ages between 60 ma and 25 ma with the greatest number of determinations around 35 5 ma this number is in excellent agreement with the stratigraphic evidence and shows that mmm took place during latest eocene time or at the transition from eocene to oligocene time along the northern border of the massif deformation and metamorphism had already taken place during the late cretaceous in a high pressure low temperature hp lt metamorphic belt northernmost part of menderes massif sensu lato which was then covered by palaeocene molasse the evolution of the hp lt belt was probably related to the obduction of the bozkir ophiolites from the izmir ankara branch of the neo tethys ocean and preceded terminal collision in the evolution of the massif the mmm was a product of the latest palaeocene collision across neo tethys and the consequent internal imbrication of the menderes taurus block that resulted in the burial of the menderes massif area beneath the lycian nappe complex a low grade metamorphic event dated at 10 to 5 ma is interpreted to be related to the extensional deformation in the aegean and western turkey which has been dated stratigraphically to have begun during the tortonian 11 5 ma

palaeoclimate and palaeovegetation in central india during the upper cretaceous based on stable isotope composition of the palaeosol carbonates abstract the oxygen isotope compositions of the pedogenic carbonates formed on the sediments of the lameta formation of central india during the upper cretaceous range from 6 7 to 8 9 estimates of the oxygen isotope composition of the soil water in equilibrium with the carbonates suggest average meteoric water composition of 8 this value is considerably lighter compared to the modern precipitation in central india 3 the lighter oxygen isotope composition can be explained in terms of cumulative effects of highly seasonal monsoon like climatic regime in a rain shadow zone and a more pronounced continental effect due to a bigger size of cretaceous india the carbon isotopic compositions of the lameta carbonates range from 7 1 to 10 7 with an average of 9 1 suggesting pedogenesis in soils dominated by c 3 type of vegetation the estimated average composition of the vegetation is about 3 enriched compared to the modern day c 3 vegetation this is probably due to atmospheric influence contributing about 15 of the total co 2 in the soil an analysis of this contribution using the model of cerling 1991 indicates that the partial pressure of co 2 in the late cretaceous atmosphere was 800 12 000 ppmv

estimating rates of calcrete formation and sediment accretion in ancient alluvial deposits the use of calcrete horizons as a means of assessing rates of sediment accretion in ancient alluvial sequences is reviewed any attempt to use such horizons in quantifying ancient alluvial deposition must appreciate that accurate data on rates of formation of quaternary calcretes are limited such data show considerable variations in the rates and no reliable data exist at all for some calcrete types the abundance of calcretes in the geological record warrants a new initiative to improve our understanding oftheir origins and rates of formation

dolomitized calcrete in the middle devonian winnipegosis carbonate mounds subsurface of south central saskatchewan canada dolomitized calcrete is a widespread diagenetic feature in the uppermost portions of the middle devonian winnipegosis mud mounds in the subsurface of south central saskatchewan individual calcrete profiles are composed of 2 to 5 horizons including in descending order laminar crust massive pisolitic breccia chalky and transitional horizons the calcrete profiles are interpreted to be pedogenic in origin formed by diagenetic alteration of the host carbonate deposits during subaerial exposure of the mud mounds this interpretation is based on the occurrence of an orderly set of well differentiated horizons disconformities vadose pisoids micritic stringers circumgranular cracks linkage coatings and gradational contacts between the calcrete and underlying host carbonate rocks lack of root related structures such as rhizoconcretion and alveolar septal fabric in the winnipegosis calcrete suggests a limited influence of macrophytes on the formation of calcrete the occurrence of up to three discrete pedogenic calcrete profiles in a single winnipegosis calcrete succession indicates the mounds underwent three periods of subaerial exposure that resulted from drops of water level in the elk point basin of saskatchewan during middle devonian time d 2004 elsevier b v all rights reserved

concentration of carbon dioxide in the late cretaceous atmosphere stable carbon isotope data from late cretaceous maastrichtian palaeosols in india are used to estimate the concentration of carbon dioxide in the late cretaceous atmosphere we show that the maastrichtian atmosphere is unlikely to have contained more than about 1300 ppm by volume of co 2 this value agrees with an independently modeled value of co 2 in the late cretaceous atmosphere a low concentration of the greenhouse gas carbon dioxide in the maastrichtian atmosphere relative to concentrations in the earlier cretaceous is consistent with palaeotemperature information from terrestrial plant and marine fossils which suggest that the global climate cooled toward the end of the cretaceous period

active tectonics of the alpine himalayan belt between western turkey and pakistan summary over 80 new fault plane solutions combined with satellite imagery as well as both modern and historical observations of earthquake faulting are used to investigate the active tectonics of the middle east between western turkey and pakistan the deformation of the western part of this region is dominated by the movement of continental material laterally away from the lake van region in eastern turkey this movement helps to avoid crustal thickening in the van region and allows some of the shortening between arabia and eurasia to be taken up by the thrusting of continental material over oceanic type basement in the southern caspian mediterranean makran and black sea thus central turkey bounded by the north and east anatolian strike slip faults is moving west from the van region and overrides the eastern mediterranean at two intermediate depth seismic zones one extending between antalya bay and southern cyprus and the other further west in the hellenic trench the motion of northern iran eastwards from the van region is achieved mainly by a conjugate system of strike slip faults and leads to the low angle thrusting of iran over the southern caspian sea the seismicity of the caucasus shows predominantly shortening perpendicular to the regional strike but there is also some minor elongation along the strike of the belt as the causcasus overrides the caspian and black seas the deformation of the eastern part of this region is dominated by the shortening of iran against the stable borders of turkmenistan and afghanistan the north east direction of compression seen in zagros is also seen in north east iran and the kopet dag where the shortening is taken up by a combination of strike slip and thrust faulting large structural as well as palaeomagnetic rotations are likely to have occurred in ne iran as a result of this style of deformation north south strike slip faults in southern iran allow some movement of material away from the collision zone in ne iran towards the makran subduction zone where genuinely intermediate depth seismicity is seen within this broad deforming belt large areas such as central turkey nw iran azerbaijan central iran and the southern caspian appear to be almost aseismic and therefore to behave as relatively rigid blocks surrounded by active belts 200 300 km wide the motion of these blocks can usefully be described by poles of rotation the poles presented in this paper predict motions consistent with those observed and also predict the opening of the gulf of iskenderun ne of cyprus the change within the zagros mountains from strike slip faulting in the nw to intense thrusting in the se and the relatively feeble seismicity in se iran baluchistan this description also explains why the north south structures along the iran afghanistan border do not cut the east west ranges of the makran within the active belts surrounding the relatively aseismic blocks a continuum approach is needed for a description of the deformation even though motions at the surface may be concentrated on faults the evolution of fault systems within the active zones is controlled by geometric constraints such as the requirement that simultaneously active faults do not in general intersect many of the active processes discussed in this paper particularly large scale rotations and lateral movement along the regional strike are likely to have caused substantial complexities in older mountain belts and should be accounted for in any reconstructions of them

petrogenesis of extension related alkaline volcanism in karaburhan sivrihisar eskisehir nw anatolia turkey abstract alkaline lavas were erupted as phonolites and trachytes around karaburhan sivrihisar eskisehir nw anatolia within the izmir ankara erzincan suture zone these volcanic rocks were emplaced as domes close and parallel to the ophiolite thrust line according to 40ar 39ar geochronological analyses of sanidine crystals from the phonolites the age of the alkaline volcanics is 25 ma late oligocene early miocene the flow textured phonolites are porphyritic and consist mainly of sanidine clinopyroxene and feldspathoid crystals the clinopyroxenes show compositional zoning with aegirine na0 82 0 96fe 30 68 0 83 rims and aegirine augite cores containing calcium magnesium and fe 2 some aegirine augites are replaced with sodium calcium and magnesium rich amphibole hastingsite feldspathoid hauyne crystals enriched with elemental na and ca have been almost completely altered to zeolite and carbonate minerals the fine grained trachytes with a trachytic texture consist of feldspar oligoclase and sanidine phenocrystals and clinopyroxene microphenocrystals within a groundmass made up largely of alkali feldspar microlites although there are some differences in their element patterns the phonolites and trachytes exhibit enrichment in liles sr k rb ba th and lrees la ce pr nd and negative anomalies in nb and ta these geochemical characteristics indicate a lithospheric mantle enriched by fluids extracted from the subduction component in addition the high 87sr 86sr 0 706358 0 708052 and low 143nd 144nd 0 512546 0 512646 isotope concentrations of the alkaline lavas reflect a mantle source that has undergone metasomatism by subduction derived fluids petrogenetic modeling indicates that the alkaline lavas generated from the subduction modified lithospheric mantle have undergone assimilation fractional crystallization and crustal contamination acquiring high pb ba rb and sr contents and pb isotopic compositions during their ascent through the thickened crust in an extensional setting

early miocene climate and biomes of turkey evidence from leaf fossils dispersed pollen and petrified wood abstract the early miocene was a period of major palaeogeographic reorganization in the eastern mediterranean region during which time the anatolian plateau became subaerial and several intracontinental basins intermittently became connected to the paratethys and mediterranean seas in this paper we analyse early miocene vegetation and climate using leaf records palynological assemblages and fossil wood at 36 localities from western and central turkey most of which have precise age control based on radiometric dating and mammal faunal ages using the leaf flora of guvem bes konak kesekoy climate leaf analysis multivariate program clamp analyses and koppen signatures were employed to infer a palaeoclimate typical of modern laurel forest regions based on the palynological records abundance of various pollen taxa was used as a measure of openness of vegetation and regional presence of major tree taxa most pollen floras are dominated by tree pollen ranging from 85 to 98 and indicated widespread afforestation in the pollen diagrams shifts in dominance from swamp forest elements taxodioideae to well drained forests pinaceae indicate changes in lake levels or phases of basin development such shifts may have been associated with the development of more xeric forest vegetation wood anatomical features such as false tree rings further may indicate seasonal climate pollen diagrams and macrofossils reflect zonal and azonal broadleaf and needleleaf forest and extrazonal open vegetation the latter occurred in areas with shallow soils on volcanic rocks or limestone e g cycads dracaena or coastal areas herb dominance taxonomic composition and biogeographic affinities suggest laurel forest as a major forest biome on well drained soils and ecotones between laurel forest and broadleaf deciduous forest biomes a comparison with younger floras shows that these are neither more diverse nor more warmth loving despite an increase in global temperature mid miocene climatic optimum suggesting bottlenecks during previous oligocene cooler times for warmth loving taxa

gold in turkey a missing link in tethyan metallogeny abstract the gold metallogeny of turkey constitutes a sector of the tethyan eurasian metallogenic belt temb within the alpine himalayan orogenic system that formed from jurassic cretaceous to the present this orogenic system produced many different types of deposits related to subduction collision post collision and rifting processes gold deposits as well as other mineral deposits of turkey are mainly concentrated in late mesozoic and tertiary rocks evaluation of the gold metallogeny of turkey is based on a gis database compilation of known gold deposits and prospects currently available data show that turkey has a gold endowment including reserves and resources of approximately 31 5 m oz 979 tonnes in 51 deposits 21 of which contain more than 0 2 m oz gold the other 30 deposits contain a total of approximately 1 m oz 31 tonnes gold resources two recent discoveries kisladag and copler currently contain total resources of 17 6 m oz au 549 tonnes more than 50 of the total turkish gold endowment turkey possesses a wide spectrum of gold deposits related to mesozoic and cenozoic volcanoplutonic arcs however porphyry gold copper epithermal gold including both high and low sulfidation styles and gold rich volcanic associated massive sulfide including both kuroko and cyprus types are the most economically important to date orogenic gold including listwanite hosted placer gold and skarn hosted gold are relatively less important or abundant deposit types other potential gold systems for exploration include carlin type gold detachment fault related gold iron oxide copper gold and gold in carbonate replacement and manganese deposits

the role of fungal biomineralization in the formation of early carboniferous soil fabrics paleosols in the lower carboniferous limestones of south wales commonly contain needle fibre calcite which is an unusual form of calcite recently shown to form by the calcification of fungal hyphae in present day soils the needle fibre calcite occurs in two associations in the paleosols as coatings on sediment grains and as rhizocretions the former can be compared with the microbial grain coatings of quaternary calcretes the latter represent the sites of fungal coats on roots and are interpreted as probable ectomycorrhizae a symbiotic fungal sheath root association these findings suggest that biomineralization was important in the formation of soil fabrics during the carboniferous as it is in present day soils

timing of cenozoic extensional tectonics in west turkey the timing of the transition from compressional to extensional tectonics in the late cenozoic evolution of west turkey has been constrained by k ar geochronology from acidic volcanic rocks and tourmaline leucogranite dykes in the central and east margin respectively of the gordes basin dacites and rhyolites in the centre of the gordes neogene sedimentary basin cut both the basement ophiolites of the izmir ankara suture zone and the neogene sediments on the basin s eastern margin the leucogranites cut metamorphic basement along a major ne sw trending normal fault that controls the regional structure of the basin pebbles of these leucogranites occur in adjacent neogene turfites and conglomerates k ar dates on biotites from the central volcanic rocks vary from 18 4 0 8 ma to 16 3 0 5 ma early miocene whilst muscovite from a leucogranite on the eastern margin of the basin provides ages of 24 2 0 8 ma and 21 1 1 1 ma latest oligocene to early miocene geochronological data and field relationships demonstrate that the earlier compressional regime had been replaced by extensional tectonics by latest oligocene early miocene

a prospective sector in the tethyan metallogenic belt geology and geochronology of mineral deposits in the biga peninsula nw turkey abstract the tethyan metallogenic belt tmb extending from europe through anatolia to iran is one of the world s major metal producing belts and consists of many sectors mineral deposits of the biga peninsula in northwestern turkey exhibit in many ways the characteristics of mineral deposits found throughout the belt biga peninsula tectonically forms the westernmost part of the sakarya zone and easternmost part of the rhodope zone at the intersection of gondwana and laurasia the biga peninsula metallogeny research and exploration project created a gis inventory of mineral deposits and prospects and classified them genetically to evaluate the mineral deposit potential using genetic models based on descriptive data the gis database consisting of 128 deposits or prospects helped to generate new prospects and potential prospects this field based study indicated that the biga peninsula forms a prime target for gold copper exploration not only in turkey but in the world the current economically significant mineral deposits of the biga peninsula were shaped by cenozoic calc alkaline magmatism ranging between 52 and 18 ma and related to mainly collisional and post collisional tectonic regime epithermal au ag deposits including high hs low ls and intermediate sulfidation is styles porphyry au cu mo and base metal skarn systems are economically the most important though there are no currently economic examples of some of them in the biga peninsula other deposit types include carlin like distal disseminated au ag orogenic au especially listwanite hosted volcanogenic mn and u lateritic ferricrete fe deposits carbonate replacement cr and placers several active metal mines such as balya arapucandere and koru are operating in the biga peninsula kucukdere au ag deposit in balikesir is the only gold mine in the biga peninsula except for by product gold produced from base metal deposits results of the study show current total gold endowment of the biga peninsula including reserves and or resources is 9 18 moz gold 284 2 t contained in twelve different deposits of these only 6 contain significant gold 0 3 moz or 10 t halilaga porphyry and agi dagi and kirazli hs epithermal systems have an ongoing resource estimate and halilaga is a candidate to be one of the largest cu au deposits not only in the biga peninsula but in turkey currently newly discovered tepeoba is the largest porphyry cu mo au deposit with known resources in the biga peninsula here the first 40 ar 39 ar step heating age data conducted on some of the major hs epithermal gold deposits and causative intrusives in the biga peninsula are reported geochronological results from this project evaluated with previous studies indicate at least 3 phases of porphyry and 2 phases of high sulfidation epithermal gold mineralization in the biga peninsula the most important mineralizing phases and related host rocks for gold mineralization range from 38 to 22 ma the oligocene is especially important for economic epithermal and porphyry systems in the biga peninsula which is comparable to deposits in the oligo miocene serbomacedonian rhodope metallogenic belt of the balkan peninsula in se europe

taphonomical and palaeoecological investigation of the late cretaceous maastrichtian tustea vertebrate assemblage romania haţeg basin insights into a unique dinosaur nesting locality abstract the tustea vertebrate locality at oltoane hill northwestern part of the ha eg basin romania has provided a rich and diverse assemblage of late cretaceous maastrichtian continental vertebrates more than 800 vertebrate fossils were recovered from this locality the isolated and associated remains represent 21 different taxa including amphibians turtles lizards snakes crocodyliforms pterosaurs dinosaurs and mammals the local assemblage is overwhelmingly dominated by dinosaurs with the rhabdodontid zalmoxes as the most abundant taxon the bonebeds that yielded this fossil material occur in a stacked series of mudstone calcrete units belonging to the middle member of the densus ciula formation the taphonomical investigations suggest that the tustea assemblage is made up of attritionally accumulated politaxic remains and that it is a parautochthonous assemblage with no evidence for significant bone transport or reworking according to the synthesis of all available field data two outstanding fossiliferous levels can be identified within the tustea locality where megaloolithus eggs and hadrosauroid hatchling material are preserved together recognized here as two superposed nesting grounds such co occurrence was considered controversial since there is a long standing and quasi general consensus that eggs of the megaloolithus oogenus were laid by titanosaurian sauropods we present several alternative scenarios to account for the co occurrence of telmatosaurus hatchling remains and megaloolithid eggs in the nesting horizons and explore these alternative hypotheses by weighing the arguments supporting or contradicting them the burden of evidence derived from our sedimentological taphonomical and palaeoecological investigations at tustea is still in favour of the autochthony of the hatchlings preserved within their own nesting grounds whereas there is no such support for a titanosaurian origin of the tu tea megaloolithid eggs

petrology and geochemistry of rhizoliths from plio pleistocene fluvial and marginal lacustrine deposits east lake turkana kenya abstract recent studies of rhizoliths from the koobi fora formation plio pleistocene of east lake turkana kenya indicate that their shapes vary with the depositional environment of their host sediment vertical rhizoliths are associated with channel bar and overbank deposits of fluvial origin these rhizoliths represent the tap roots of phreatophytes that lived in well drained upland settings horizontal rhizoliths predominate in facies ascribed to beaches lagoons and floodplains associated with ancient lake turkana they are produced by water emergent aquatic macrophytes and coastal grasses that grow in saturated or poorly drained soil environments the rhizoliths consist of sparry and micritic calcite cements whose petrography and geochemistry reflect differences in diagenesis between the two types of root systems the vertical roots contain little organic debris and have poorly developed meniscus and microstalactitic cements these attributes reflect precipitation of the calcite in well oxygenated well drained vadose conditions in contrast the cements of the horizontal root systems lack textures indicative of vadose conditions contain abundant clay and plant debris and display mn concentrations as high as 4 5 cation percent these features confirm that the horizontal rhizoliths developed in chemically reduced water saturated conditions bacterial decay of the plant debris maintained reduced eh conditions while also supply ng abundant mn2 to the pore solutions groundwater that had moved through volcanic strata may have also contributed mn2 the mn may have been incorporated in the calcite cements through a combined process of chemisorption and ionic substitution of mn2 as well as by inclusion of manganese oxides

evolution of the bayramic magmatic complex northwestern anatolia abstract during the oligocene middle miocene period widespread magmatic activity developed in western anatolia following the continental collision between the sakarya continent and the tauride anatolide platform this produced both intrusive and extrusive rocks which appear to be associated in space and time as exemplified from the bayramic area in the bayramic area the magmatic activity started with the intrusion of the evciler granite and the coeval lower volcanic association this was followed by the development of the upper volcanic association these rock groups form collectively the bayramic magmatic complex which was generated under an on going north south compressional regime the bayramic magmatic complex has a subalkaline composition displaying a calcalkaline trend trace elements and ree contents resemble to island arc and collision related magmas according to the isotope values the bayramic magmatic complex was derived from the magmas of lithospheric mantle origin which were later contaminated while passing through the thick continental crust in a post collisional tectonic setting during the oligocene early miocene period the latest product of the magmatism is the late miocene pliocene basalt lavas their geochemical properties are clearly different from the oligocene early miocene magmatic rocks the basalts were generated when the north south compression gave way to the north south extensional regime

le volcanisme quaternaire d anatolie centrale turquie association de magmatismes calco alcalin et alcalin en domaine de convergence collision volcanism in central anatolia cappadocia began at least in the late miocene because of the north south arabian eurasian convergence since this period the anatolian block is displaced towards the west along the north and east anatolian strike slip faults kinematic reconstructions show that the east anatolian fault is both sinistral and convergent as a consequence the anatolian block is currently being deformed quaternary volcanism in central anatolia is represented by several hundreds of monogenetic scoria cones lava flows maars and domes as well as two strato volcanoes hasan dag and erciyes dag the monogenetic volcanism is bimodal basalts and rhyolites whereas the stratovolcanoes exhibit a complete calc alkaline suite from basalts to rhyolites most of the igneous products are calc alkaline basalts erupted mainly from the monogenetic cones lava flows and maars andesites are encountered in the strato volcanoes as lava flows domes and nuees ardentes deposits dacites and rhy

why are there no clockwise rotations along the north anatolian fault zone mechanical analysis of lithospheric deformation associated with an intracontinental transform fault suggests that it should be associated with a pattern of vertical axis rotations governed by the length of the fault its displacement and the mechanical properties of the lithosphere paleomagnetic results from two transects across the north anatolian fault zone indicate that there have been no measurable clockwise rotations on a regional scale associated with neogene dextral strike slip motion along the fault the data come from two groups of volcanic rocks that have been dated by k ar whole rock geochronology and have yielded ages ranging from 45 3 3 1 m y to 41 8 1 3 m y eocene and 21 7 1 5 m y to 7 5 0 2 m y miocene the absence of clockwise rotations suggests one of the following explanations 1 in contrast to the assumptions underlying current mechanical analyses deformation in the upper crust may not directly reflect the flow in the lithosphere and is localized along a single fault trace 2 deformation is distributed but rotations have been prevented by the presence of elongate fault blocks subparallel to the trace of the main fault 3 displacement along the north anatolian fault may be too small or the rheologic properties of the lithosphere such that rotations about vertical axes cannot be resolved instead of the predicted clockwise rotations measured declinations show that there has been approximately 30 of anticlockwise rotation of both the eocene and miocene volcanic rocks this suggests that no significant rotation occurred between eocene and miocene times and that the anticlockwise rotation occurred either immediately before or concurrent with the plio pleistocene slip on the north anatolian fault

calcretes related to phreatophytic vegetation from the middle triassic otter sandstone of south west england carbonate cementation in the triassic otter sandstone of budleigh salterton sw england occurs in two distinct forms large vertical concentrically zoned cyclinders and thin subhorizontal sheets the former represent rhizocretions of the tap roots of phreatophytic plants which colonized bars and abandoned channels on a large braidplain the sheets represent cementation around ancient water tables the precipitation of the rhizocretions took place at least in part during the life of the plants and 13c and 18o values support the view that evapo transpiration induced carbonate precipitation palaeosol profiles are rare in the otter sandstone reflecting the geomorphological instability of the braidplain surfaces in contrast rhizocretionary and sheet calcretes which formed several metres below the active depositional surface are abundant because they had a high preservation potential

near surface shrinkage and carbonate replacement processes arran cornstone formation scotland a 47 m thick succession of conglomerates sandstones and mudstones of late devonian or early carboniferous age outcrops at fallen rocks in northeast arran western scotland it is defined here as the type section of the arran cornstone formation at numerous levels in the succession varieties of fissures and carbonate concretions formed during the accumulation of the formation the fissures opened as a result of drying shrinkage and were closed again either by filling with different sediment or by wetting and expansion of the fissure wall sediment carbonate concretions form complete beds discontinuous bedding concordant sheets or bedding discordant nodules or rods the rod cornstones these concretions formed close enough to the surface to be incorporated after erosion and redeposition as clasts into overlying beds the concretions were formed by growth of micrite mainly by replacement but shrinkage displacement played an important role in subsequently fracturing and reworking the micrite the micrite was also locally replaced by microspar and spar and this involved dissolution and precipitation no independent evidence of biological influence in any of these processes has been found

genesis of collision volcanism in eastern anatolia turkey late cenozoic volcanism in eastern anatolia extends in a broad sw ne trending belt across the arabia eurasia collision zone from the arabian foreland basin in the southwest and to the kars plateau and lesser caucasus in the northeast foreland volcanism is dominated by basaltic shield and fissure eruptions of transitional tholeiitic alkaline composition volcanism on the thickened crust north of the bitlis thrust zone varies from the mildly alkaline volcano nemrut and older mus volcanics in the south through the transitional calc alkaline alkaline volcanoes bingol and suphan and the alkaline volcano tendurek to the calc alkaline volcano ararat and older kars plateau volcanics in the north isotope sr nd and trace element systematics indicate that the lavas from the foreland were derived from the mantle lithosphere of the arabian continent which had been enriched by small volumes of asthenospheric melts over a period of time and that lavas from the alkaline volcanic area around mus and the volcanoes nemrut and tendurek north of the bitlis thrust zone were derived from a lithospheric source of similar composition either from the same underthrust arabian continent or from the bitlis massif microcontinent by contrast the transitional lavas from bingol and suphan and the calc alkaline lavas from ararat and kars were derived from lithosphere carrying a distinct subduction signature inherited from pre collision subduction events positive correlations between 87sr 86sr and sio2 and rb nb and sio2 in the alkaline and transitional lavas suggest that combined assimilation and fractional crystallization was an important process within at least part of the thickened crust of the collision zone trace element covariation diagrams such as y rb indicate the importance of hornblende crystallization at depth and orthopyroxene at shallow levels within the calc alkaline provinces in contrast to the consistently anhydrous crystallization sequences of the alkaline lavas trace element diagrams based on the covariation of compatible and incompatible elements point to moderate low degrees of partial melting with residual clinopyroxene throughout and residual garnet in the foreland province consideration of mineral stabilities mantle solidi and geothermal gradients before and after collision suggest that lithospheric thickening should both increase the thickness of metasomatized lithosphere and depress the metasomatized zone to greater depths probably beneath the amphibole and dolomite breakdown curves perturbation of the thickened lithosphere by delamination of the thermal boundary layer perhaps coupled with local stretching associated with pull apart basins on strike slip fault systems is then sufficient to generate melt the composition of that melt being largely dependent on the enrichment history of the lithosphere in question in eastern anatolia volcanism appears to have started between about 8 and 6 ma ago some 5 ma after the start of rapid uplift of the east anatolian plateau

calcretes from a late quaternary interfluve in the ganga plains india carbonate types and isotopic systems in a monsoonal setting abstract calcretes are abundant in late quaternary channel and floodplain strata of the southern ganga plains in a key section at kalpi pedogenic carbonates nodules rhizoconcretions and powdery carbonate are present within aggradational floodplain deposits where they correspond to relatively high monsoonal precipitation and river discharge in contrast groundwater carbonate has cemented degradational surfaces discontinuities which correspond with periods of relatively low precipitation mixed groundwater and pedogenic calcretes are present in the deposits of small interfluve channels and reworked nodules line degradational surfaces and locally fill channels most carbonates show alpha fabrics that include floating textures shrinkage crack fills and grain coatings the predominance of alpha fabrics is unexpected but is characteristic of calcretes across dryland and seasonal parts of northern india where soil formation led to only weakly developed or poorly preserved beta fabrics interpretation of 13c and 18o values of bulk and microdrilled calcrete samples suggests relatively little variation in precipitation and vegetation types through the sampled interval at kalpi floodplain deposits were vegetated with a mixture of c4 and c3 plants predominantly c4 with a higher proportion of c3 plants associated with channel deposits this apparent lack of variation is surprising because the sampled interval represents at least 60 000 years of marine isotope stages 3 5 during which climate models suggest that asia experienced radical fluctuations in monsoon intensity and precipitation some of the apparent lack of variation may be explained by preferential preservation of aggradational strata that represent relatively active monsoonal periods as well as by the mixing of drier floodplain c4 and riparian c3 vegetation however local departures from the regionally based climate model cannot be ruled out a modest upsection increase in c4 plants may represent increased aridity and lower atmospheric co2 isotopic analysis of organic matter from floodplain pedogenic nodules suggests a higher c3 plant contribution than carbonate based data would suggest the preserved organic matter may reflect the annual average biomass in the soil whereas carbonate formation may have taken place mainly during the drier season when respiration of c4 plants was more important in interfluve settings such as kalpi seasonality may strongly affect the c3 c4 system with preferential preservation of only part of the biomass

dynamic model of the genesis of calcretes replacing silicate rocks in semi arid regions abstract in both pedogenic and groundwater calcretes calcium carbonate precipitates in voids or displacing other grains or replacing underlying parent silicates replacement textures are widespread in pedogenic calcrete many calcretes also contain magnesium layer silicates and minor chert we present a reaction transport model that accounts for the genesis of replacement in calcretes and for their mineralogy replacement is difficult to account for geochemically because it requires simultaneous removal of large amounts of silicates and import of also large amounts of caco 3 in the model the genesis of replacement is directly related to seasonally alternating dry wet climates and to appropriate groundwater or circulating soil water compositions in a dry season water evaporation causes caco 3 and sepiolite or attapulgite to precipitate if groundwater contains enough mg 2 sepiolite precipitation by the chemical divide mechanism depletes sio 2 aq resulting in the dissolution of parent silicates in the following wet season sepiolite dissolves fast and silica and cations are flushed away by rainwater making room for caco 3 precipitation in the next dry season as climate cycles repeat caco 3 is accumulated and silicates are removed the sepiolite or attapulgite or mg smectite serves as a temporary storage of silica between seasons if the groundwater contains too little aqueous mg then the model predicts growth of calcium carbonate without removing silicates thus producing void filling and or displacive textures instead of replacement the model consists of a set of nonlinear partial differential equations taking account of mass conservation dispersion advection rainwater infiltration evaporation and the kinetics of mineral reactions the hydrodynamics of unsaturated media is applied in determining water flow in calcrete profiles wet dry seasonal changes are incorporated by alternating the upper boundary conditions the model successfully produces the mineral and textural zonation observed in many calcretes namely at the bottom of the profile the parent rock is first replaced by sepiolite only part of which is in turn replaced by calcite whereas at the top of the calcrete the sepiolite is itself completely replaced by the calcite which appears to directly replace the parent rock the model can produce calcrete near the earth s surface well above the water table low p co 2 intensive evaporation and long dry seasons all are predicted to produce thicker calcretes calcretes constitute an effective geochemical tool that via replacement removes parent silicate rocks and shapes the landscape of semi arid countries the model herein provides a mechanism that accounts for the efficiency of replacement in removing silicates

late cenozoic tectonics and volcanism along the north anatolian fault new structural and geochemical data abstract different types of volcanic activity have developed along the north anatolian fault zone naf in turkey detailed analysis of satellite images and digital elevation models dems and field observations have been made in order to understand the tectonics and the distribution of volcanic vents in the anatolian block some faults are oblique to the naf and delimit extensional escape wedges vents rooted on open tension fractures show that emplacement of the volcanism is related to tensional fracturing of the anatolian continental block which we attribute to the onset of free borders in the south and west along the naf earliest extension 1 is directed s to ssw and the latest 2 towards w to wsw parallel to the sinistral slip along the naf major and trace element geochemical data indicate that the dominant calc alkaline rocks are associated with various alkaline lavas k ar ages of the volcanics range from 22 to 8 5 ma in galatia massif 900 to 100 ka in niksar and 3 to 12 ka in erzincan isotopic and trace element data are interpreted as reflecting a dominantly lithospheric mantle source slightly mixed with asthenospheric liquids most magmas were fractionated and contaminated by continental crust during their ascent 1 and 2 tectono volcanic events have propagated through time and space from west to east the 1 extension is late oligocene in the galatia massif late miocene in niksar and late pliocene in erzincan the 2 extension and strike slip event along the naf began in the late miocene in the galatia massif early pliocene in niksar and quaternary in erzincan signature from an asthenospheric source in the second event in the three regions suggests that an ancient suture zone galatia massif and or the lithospheric naf transform niksar and erzincan have served to channel small quantities of asthenospheric melts existing at the base of the lithosphere

the influence of the water saturation on the strength of volcanic tuffs used as building stones moisture content is one of the most important factors influencing the strength of building stones ayazini and seydiler afyonkarahisar turkey tuffs were investigated with the goal to determine the influence of the water on their strength mercury porosimetry was used to determine the pore size distribution ayazini tuffs have pore sizes ranging from about 200 000 to 10 nm and seydiler tuffs ranging from about 7000 to 10 nm the tuff samples are immersed in water with different time periods of 1 6 24 and 48 h the following physico mechanical properties were measured for all the samples both in dry and saturated condition compressive strength and flexural strength test results were indicated by simple regression analysis good correlations were found between physico mechanical properties with dry and saturated tuff samples the results had shown their mechanical strength decreases in wet conditions for dry samples tested had 22 21 mpa uniaxial compression strength while 1 h immersed samples had 15 11 mpa which indicates a decrease of 31 96 after the 48 h water immersion time period the value of compression strength decreases by 43 99 and becomes 12 44 mpa

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

a magnetite rich cyprus type vms deposit in ortaklar a unique vms style in the tethyan metallogenic belt gaziantep turkey abstract the ortaklar vms deposit is hosted in the kocali complex consisting of basalts and deep sea pelagic sediments which formed by rifting and continental break up of the southern neotethyan in late triassic the basalts are of nmorb type without notable crustal contamination from the surface to depth the ortaklar deposit consists of a gossan zone a thick massive ore zone and a poorly developed stockwork zone primary mineralisation is characterised by distinctive facies including sulphide breccias proximal graded beds distal stockworks and chimney fragments ore mineral abundances decrease in the order of pyrite magnetite chalcopyrite and sphalerite two distinct phases of mineralisation massive magnetite and massive sulphide are present in the ortaklar deposit textural evidence e g magnetite replacing sulphides and the spatial relationships with the host rocks indicate that magnetite and sulphide minerals were generated in different stages the transition from sulphide to magnetite mineralisation is interpreted to relate to variation in h2s content of ore fluids the 1st stage massive sulphide ore might have formed by early hydrothermal fluids rich in fe and h2s the 2nd stage massive magnetite might have formed by later neutral hydrothermal fluids rich in fe but poor in h2s replacing the pre existing sulphide ore the alteration patterns mineral paragenesis lithological features massive ore stockwork ore gossan of the ortaklar deposit together with its trace elements cu pb zn au ag and ree signatures are all consistent with a cyprus type vms system the 34s values in pyrite and chalcopyrite samples range from 2 6 to 5 7 indicating that the hydrothermal fluids were associated with sub seafloor igneous activity typical of cyprus type vms deposits however magnetite formed later than sulphide minerals in the ortaklar deposit contrasting with typical cyprus type vms deposits where magnetite generally occurs in lower sections consequently although the ortaklar deposit generally conforms to cyprus type deposits it is distinguished from them by its late stage and high magnetite concentration thus the ortaklar deposit is thought to be an exceptional and perhaps unique cyprus type vms deposit

helium isotope variations in turkey relationship to tectonics volcanism and recent seismic activities the distribution of helium isotope ratios in the various tectonic provinces of turkey is examined through a synthesis of previously published data and the results of a recent survey along the north anatolian fault zone nafz following the catastrophic 1999 earthquakes the r ra values where r sample 3he 4he and ra air 3he 4he cover a wide range from 0 05 to 7 87 and the mantle derived helium is clearly identified in most locations the mantle derived component is high 50 of total he in a regions of central and eastern anatolia both of which are associated with historically active volcanoes and b the seismically active west to central segment of nafz while the mantle contribution reaches a maximum at nemrut volcano in eastern anatolia a region of dominantly compressional tectonics and with moderate enthalpy geothermal fields it is relatively low 50 in the western anatolian extensional province even though this region has the highest geothermal potential the average 3he enthalpy ratios estimated for the different provinces suggest lithospheric stretching and rise of the geotherm as the major mechanism of high heat flow yet limited intrusive activity in western anatolia is suggested as the reason for the comparatively low he additions and consequently low 1 7 106 atoms j 3he enthalpy ratios a more extensive magmatic activity appears to be responsible for the greater input of both heat and helium in eastern and central anatolia with intra province 3he enthalpy variations from 3 1 106 atoms j in eastern to 0 25 106 atoms j in central anatolia reflecting the ageing of hydro magmatic systems the relatively high 3he concentrations in low enthalpy waters of northern anatolia 2 8 106 atoms j are particularly significant since there is no evidence of volcanic activity associated with the strike slip motion along the seismically active segment of nafz continuous monitoring of he isotope compositions along nafz should lead to a better understanding of this apparent anomaly as well as the relationship if any between he isotope variations and seismic activities in this region

records of the influence of deccan volcanism on contemporary sedimentary environments in central india deccan volcanism with a duration of 5 myr represents a major continental flood basalt province in which 2 million km3 of lavas were formed such voluminous and rapid volcanism in phanerozoic earth history has commonly been advanced as a cause for mass extinctions despite this significance few studies have attempted to understand the influence of continental flood basalt volcanism on contemporary sedimentary environments thin sedimentary sequences associated with the deccan volcanics i e the infra and inter trappean sequences offer an opportunity to assess the influence of deccan volcanism on contemporary sedimentary environments in central india the lameta formation mainly constitutes a well characterised regolith regionally consisting of calcretes and palustrine facies which may in places be associated with ephemeral sandy braided river and sheetflood facies an assessment of the influence of deccan volcanism on contemporary surficial environments reveals a an input of basaltic degradational products in the basal fluvial facies of the lameta formation b upward changes in facies assemblages from lacustrine palustrine to subaerial dominated followed eventually by burial by the first lavas locally c significant changes in the palaeoflow characteristics of fluvial channel facies respectively under and overlying the main calcareous regolith of the lameta formation d that most freshwater lacustrine taxa survived the initial effects of the deccan volcanism without undergoing any drastic change in addition to the role of constructional topography resulting from lava emplacement and associated surface uplift the mode of preservation of sedimentary packets significantly affects changes in the vertical motifs of coeval sedimentary sequences because of the problems of time resolution on 105 106 year time scales in the continental infra and inter trappean sequences detailed cause volcanism effect surficial environments relationships at the event level are not well understood also the lack of data from multiple stratigraphic levels of the inter trappean beds precludes any serious assessment of the directions and rates of changes that took place in co2 concentrations of the palaeoatmospheres of that period 65 3 myr

lignite oxidation under the influence of glacially derived groundwater the pyropissite deposits of zeitz weisenfels germany abstract the middle eocene lignites of the zeitz weisenfels coal mining area in central germany hosted one of the most economically successful lithotypes of lignite deposits utilised in the paraffin industry of the 19th century i e the pyropissite deposits however due to their economic significance these rare lithotypes were almost completely mined out such that presently only a few remnant deposits are known apart from the zeitz weisenfels coal mining district other pyropissite deposits were also encountered in other lignite mines for instance in the hessian and subhercynian basins pyropissite is a whitish and bitumen rich variety of soft brown coal lignite lithotypes dominated by a homogeneous matrix with loosely embedded organic and inorganic components fresh exposure of pyropissite at grana was logged and studied petrographically and geochemically along with samples obtained from archival collections results were compared with those from the 19th and 20th century to derive general conclusions regarding origin and formation of pyropissite microscopically the main constituent of this special lignite lithotype is amorphous to detrital in appearance according to w schneider the term xanthinite is applied to this component which forms the groundmass of the pyropissite it contains high proportions of liptinitic substances with contributions of formless huminitic material and minor amounts of mineral matter geochemically pyropissite is characterised by an increased h c atomic ratio and a very high content of bitumen in terms of toluene soluble components as well as low temperature carbonisation tar the obtained data revealed that the extraordinarily high content of liptinite and the paucity of huminitic material of the pyropissite deposits of the zeitz weisenfels coal mining area are not related to primary depositional processes but rather are the result of dissipation of high condensed huminites and the consequent enrichment of liptinitic substances the mechanism involves oxidation by groundwater and is related to glaciation processes operating during the pleistocence such glacially derived processes also account for both vertical and horizontal distributions of the pyropissite thus recent research activities may also serve as an innovative inspiration to fundamental understanding of the formation of lignites with extremely high liptinite content

biodiversity during the deccan volcanic eruptive episode this paper gives a detailed overview of biotic assemblages recovered from the deccan trap intercalated sedimentary sequences infra and intertrappean beds of peninsular india as a result of extensive research done during the last 20 years the infra and intertrappean beds contain remnants of gondwanan forms such as myobatrachinae frogs pelomedusid turtles dinosaurs i e titanosaurids and abelisaurids and mammals apart from these gondwanan elements the infra and intertrappean beds also contain forms of laurasian affinity though recently doubt has been cast on such relationships based on previous fossil records laurasiatic forms were considered to be represented by a great variety of micro and megavertebrate assemblages such as discoglossid and pelobatid frogs anguid lizards alligatorid crocodiles palaeoryctid mammals charophytes and ostracodes the biotic assemblages show a remarkable similarity between the infra and intertrappean beds indicating a short time period for the deposition of these deccan volcano sedimentary beds the recovered biotic assemblages strongly indicate a maastrichtian age for the initiation of deccan volcanic activity and the sedimentary beds associated with it the cretaceous tertiary boundary as such remains to be defined in any known sections in sedimentary sequences in so far investigated localities of peninsular india what have been identified are maastrichtian age beds in the east central and western narmada river region on the basis of pollens vertebrate assemblage and planktonic foraminiferas in infratrappean offshore sequences a palaeocene intertrappean bed at lalitpur uttar pradesh that is among those lacking dinosaurian remains but having palynological assemblages similar to those from well established palaeocene sequences suggests the presence of palaeocene intertrappeans but the k t boundary is yet to be properly defined