sedimentary pyrite formation an update sedimentary pyrite formation during early diagenesis is a major process for controlling the oxygen level of the atmosphere and the sulfate concentration in seawater over geologic time the amount of pyrite that may form in a sediment is limited by the rates of supply of decomposable organic matter dissolved sulfate and reactive detrital iron minerals organic matter appears to be the major control on pyrite formation in normal non euxinic terrigenous marine sediments where dissolved sulfate and iron minerals are abundant by contrast pyrite formation in non marine freshwater sediments is severely limited by low concentrations of sulfate and this characteristic can be used to distinguish ancient organic rich fresh water shales from marine shales under marine euxinic conditions sufficient h2s is produced that the dominant control on pyrite formation is the availability of reactive iron minerals calculations based on a sulfur isotope model indicate that over phanerozoic time the worldwide average organic carbon to pyrite sulfur ratio of sedimentary rocks has varied considerably high cs ratios during permo carboniferous time can be explained by a shift of major organic deposition from the oceans to the land which resulted in the formation of vast coal swamps at that time low cs ratios compared to today during the early paleozoic can be explained in terms of a greater abundance of euxinic basins combined with deposition of a more reactive type of organic matter in the remaining oxygenated portions of the ocean the latter could have been due to lower oceanic oxygen levels and or a lack of transportation of refractory terrestrial organic matter to the marine environment due to the absence of vascular land plants at that time

precipitation driven decadal scale decline and recovery of wetlands of lake pannon during the tortonian high resolution pollen and dinoflagellate analyses were performed on a continuous 98 cm long core from tortonian deposits of lake pannon in the styrian basin in austria the sample distance of 1 cm corresponds to a resolution of roughly one decade allowing insights into environmental and climatic changes over a millennium of late miocene time shifts in lake level surface water productivity on a decadal to centennial scale can be explained by variations of rainfall during the tortonian climatic optimum related to negative fine scale shifts of mean annual precipitation shoreline vegetation belts reacted in an immediate replacement of poaceae by cyperaceae as dominant grasses in the marshes fringing the lake in contrast to such near synchronous ecosystem responses to precipitation a delayed lake level rise of 4 6 decades is evident in the hydrological budget of lake pannon this transgression caused by a precipitation increase up to 1200 mm yr resulted in a complete dieback of marshes simultaneously open water dinoflagellates such as impagidinium took over in the brackish lagoon and fresh water dinoflagellates disappeared as soon as the rainfall switched back to moderate levels of 1100 1200 mm yr the rise of the lake level slowed down the marsh plants could keep up again and the former vegetation belts became re established thus mean annual precipitation more than temperature was the main driving force for high frequency fluctuations in the tortonian wetlands and surface water conditions of lake pannon such high resolution studies focusing on tortonian decadal to centennial climate change will be crucial to test climate models which try to compare the tortonian models with predictions for future climate change

environmental control on mediterranean salinity and δ18o a box model is presented to simulate changes in mediterranean long term average salinity and 18o over the past 20 000 years simulations are validated by comparison with observations sensitivity tests illustrate robustness with respect to the main assumptions and uncertainties the results show that relative humidity over the mediterranean remained relatively constant around 70 apparently narrowly constrained to the lower end of the range observed globally over sea surfaces by the basin s land locked character isotopic depletion in run off relative to the present is identified as the main potential cause of depletions in the mediterranean 18o record also slight increases in relative humidity of the order of 5 might have caused very pronounced isotopic depletions such as that in sapropel s5 of the penultimate interglacial maximum the model shows distinctly non proportional responses of 18o and salinity to environmental change which argues against the use of isotope residuals in mediterranean paleosalinity reconstructions

stratigraphy and strontium geochemistry of messinian evaporite bearing successions of the southern apennines foredeep italy implications for the mediterranean salinity crisis and regional palaeogeography an integrated study comprising detailed mapping stratigraphy evaporite facies analysis strontium content and 87sr 86sr ratio data is presented for two messinian evaporite bearing units cropping out in irpinia daunia mountains southern apennines italy these units record the tectonic and palaeogeographic evolution of the messinian southern apennine foreland basin system during the abrupt salinity crisis which occurred in the mediterranean region the daunia unit comprises the monte castello evaporites formed by euxinic diatomitic marls evaporitic limestones and shallow water gypsum having a 87sr 86sr average value of 0 70898 0 00005 close to the sr isotopic value of the coeval seawater these marginal evaporites are capped by an erosional unconformity and continental clastic deposits the vallone del toro unit is made up of thin bedded marls claystones calcilutites and diatomite layers with small gypsum crystals laminated gypsum and gypsarenite testifying deposition in relatively deep water settings gypsum has variable sr isotopic data with an average value of 0 70899 0 00005 for the argilliti policrome del torrente calaggio formation and an average value of 0 70863 0 00014 for the argilliti di mezzana di forte formation reflecting major riverine freshwater input the different patterns of lithofacies and sr isotopic composition of gypsum discriminate two distinctive evaporite units reflecting the tectonic and palaeogeographic controls within the apennines mountain belt and the mediterranean data for evaporites of the southern apennines testify the presence of basins in the central and eastern mediterranean sea which never desiccated during the entire salinity crisis and evolved to widespread lago mare conditions in the latest messinian

mio pliocene magnetostratigraphy in the southern carpathian foredeep and mediterranean paratethys correlations a full understanding of the mio pliocene palaeogeographical and palaeoenvironmental changes in the circum mediterranean region during the messinian salinity crisis msc is at present hampered by the lack of reliable chronostratigraphic correlations between the mediterranean and paratethys regions here we present magnetostratigraphic ages for the upper miocene to pliocene deposits of the southern carpathian foredeep in romania these ages are in good agreement with those recently obtained from the eastern carpathian foredeep and define a new chronology for the eastern paratethys the meotian pontian boundary is not biostratigraphically

life cycle of the east carpathian orogen erosion history of a doubly vergent critical wedge assessed by fission track thermochronology apatite fission track b t thermochronology applied to the east carpathian fold and thrust belt in romania constrains the interaction between the erosion history and the tectonic evo lution of the orogen the long lived constant asymmetric topography of the orogen and the erosion pattern as inferred from apatite ft data are in agreement with the style of evolution predicted by doubly vergent critical coulomb wedge models during the miocene up to 4 km of erosion took place over the actively deforming orogen and the erosion patterns forms a mirrored image of the subsurface deforming wedge the erosion products are deposited in flanking molasse basins which subsided contemporaneously due to the growing topographic weight of the wedge deformation of the wedge was presumably active from the early to late miocene but apatite ft ages between 14 and 9 ma and track length modeling predict an acceleration of erosion rates 0 5 0 3 mm yr ini tially in the middle to late miocene 3 2 ma the onset of erosion coincides with the last phase of convergence and a climax in the deformation history these features are interpreted to have been caused by underplating of the european continental margin convergence ceased before the pliocene according to the activity of thrust faults during the pliocene and quaternary up to 2 km of overburden was removed by erosion leading to isostatic rock uplift of the entire region the use of apatite fission track minimum ages supports the general idea that the orogen has a di achronous evolution from north to south the orogen in the southern bend zone has a more juve nile tectonic character and the main erosion phase took place during the pliocene and quaternary 5 0 ma the integrated approach of large scale morphology and fission track analysis confirms the applicability of the theoretical coulomb wedge mechanics to a natural compressive fold and thrust belt the study complements the geometric features of the orogenic wedge with quantified erosion histories and illustrates the effects of orogen evolution on vertical movements in the entire convergent setting

inconsistent magnetic polarities between greigite and pyrrhotite magnetite bearing marine sediments from the tsailiao chi section southwestern taiwan abstract to establish a magnetobiostratigraphy for a 620 m thick middle to late pleistocene mudstone sequence in the lower gutingkeng formation of the tsailiao chi tlc section in southwestern taiwan we conducted paleomagnetic and mineral magnetic measurements together with sediment granulometry and calcareous nannofossil identification paleomagnetic samples from 65 sites revealed two types of thermal demagnetization 25 400 c behavior 1 single component stable characteristic remanence in magnetite and pyrrhotite dominated samples type s and 2 abrupt changes in polarity when samples with significant greigite concentrations were heated above 320 340 c type c the characteristic polarities derived from type s samples and from magnetite dominated type c samples obtained above 340 c are consistent with those determined from nannofossil biostratigraphy this implies that the nrm carried by magnetite and pyrrhotite is reliable the essentially antiparallel remanence components in type c samples below 340 c are attributed to greigite the almost antiparallel direction could have resulted from delayed formation of greigite but in this case the different direction of this component must have resulted from variable remanence lock in times alternatively the opposite polarities may result from self reversal which warrants further investigation pyrrhotite and greigite may have both formed authigenically but there is no clear explanation for the observed differences in direction

wave field processing of data from a large aperture seismic experiment in southwestern oklahoma data from a wide aperture survey performed in january 1985 in southwestern oklahoma have been processed using prestack imaging and the images are interpreted to reveal a new picture of the crustal structure in the wichita uplift and the anadarko basin as the data were in recording apertures of approximately 90 km it was necessary to develop new processing concepts and software a complete new imaging system based on common source gathers was conceived implemented tested and applied to these data the heart of the system consists of velocity estimation by slant stacking and acoustic prestack reverse time finite difference migration the migration produces reflectivity images in regions of 50 km 100 km has no dip restrictions and operates in an arbitrarily complicated two dimensional velocity distribution for comparison the data were also processed using standard common midpoint processing but this is a less valid approach for wide aperture data the main ambiguities and limitations in processing and interpretation are a consequence of the small number of shots processing and interpretation of the data provide a new picture of the subsurface structure of southwestern oklahoma the environment is clearly compressive with thrust faulting as the main accommodating mechanism in the upper and central crust beneath a possible detachment zone at 30 km depth the lower crust has responded to the compression by thickening by 50 the moho is interpreted to be 45 km in depth beneath the thrust zone shallowing to 40 km beneath the wichita uplift and the anadarko basin

cocorp profiling across the southern oklahoma aulacogen overthrusting of the wichita mountains and compression within the anadarko basin cocorp consortium for continental reflection profiling deep reflection profiles recorded across the wichita mountains and anadarko basin suggest that significant crustal shortening occurred in the final stages of the evolution of the southern oklahoma aulacogen the crystalline rocks of the wichita mountains were thrust in pennsylvanian time northeastward over sedimentary rocks of the anadarko basin along a series of faults with moderate average 30 to 40 and southwesterly dips these faults can be traced possibly as deep as 20 to 24 km listric thrust faults and hanging wall anticlines developed in the sedimentary rocks of the basin these features contrast with conventional interpretations of pennsylvanian structures as the result of predominantly vertical movements along high angle faults and they suggest that pennsylvanian downwarping of the anadarko basin was at least partially due to thrust loading truncations of reflections from cambrian ordovician rocks in the deepest part of the basin suggest normal faulting which would support ideas of an early extensional stage in the aulacogen cycle the distinctive precambrian layering seen on earlier cocorp data recorded south of the wichita mountains cannot be recognized under the anadarko basin and the proterozoic basin containing that layering may have been bounded on its north side by a precambrian fault this inferred fault was probably twice reactivated during formation of the southern oklahoma aulacogen once during late precambrian early cambrian extension and again during pennsylvanian compression the popular view that aulacogens originated from radial rifting of updomed homogeneous continental crust is probably too simplified and a more important constraint on their location and development may be the nature of pre existing lines of weakness

quantification of magnetic coercivity components by the analysis of acquisition curves of isothermal remanent magnetisation abstract a new method of analysing isothermal remanent magnetisation irm acquisition curves based on cumulative log gaussian analysis robertson and france phys earth planet inter 82 1994 223 234 is proposed it is based on the curve fitting of the irm acquisition curve versus the logarithm of the applied field with i the acquisition curve on a linear scale ii the acquisition curve expressed as a gradient and iii the acquisition curve on a probability scale even when a sample is not saturated its magnetic properties can be defined although with less certainty the number of magnetic components required for an optimal fit to a measured irm acquisition curve is evaluated statistically the method discriminates on the basis of different mineral coercivity therefore additional rock magnetic tests are still required to separate minerals with similar coercivities

the transylvanian basin romania and its relation to the carpathian fold and thrust belt insights in gravitational salt tectonics abstract interpretation of regional seismic profiles stratigraphic and sedimentologic data improved insights in the evolution of the transylvanian basin the basin evolution was coeval with the post mid cretaceous to recent deformation of the carpathian mts four tectonostratigraphic megasequences are differentiated upper cretaceous rift paleogene sag lower miocene flexural basin and middle to upper miocene backarc sequence dominated by gravitational tectonics the mid miocene continental collision in the eastern carpathians is associated with the rising carpathians this uplift enhanced the differential load which together with the high heat flow induced by late miocene to pliocene arc volcanism triggered large scale mio pliocene gravity spreading of the salt overburden this mega slide comprises three structural domains as follows extensional weld upslope contractional folds central and contractional toe thrust downslope the diapirs in the east indicate a pre shortening reactive passive growth stage the central folds are mostly the result of late shortening basement involved thrusting uplifted the toe thrust domain by the late pliocene the late neogene to recent carpathians uplift backarc volcanism and gravity spreading are largely coeval

timing and chemistry of igneous events associated with the southern oklahoma aulacogen abstract igneous activity in the southern oklahoma aulacogen of north america was concentrated in the early rifting stages of aulacogen development the time span over which liquids rose may not have exceeded 50 m y and certainly terminated before the upper cambrian igneous activity began with three basaltic liquids stratigraphically identifiable but perhaps not all distinct genetically this was followed by one large rhyolitic granitic episode of a type character one final basaltic event ended the activity all the basaltic types seem to be tholeiitic showing more kinship with either the older proterozoic north american midcontinental rift or the northern part of the cenozoic rio grande rift than the cenozoic east african rift two major uplifts occurred one between the earlier basalts and the rhyolite and one much later after all igneous activity was over in the pennsylvanian

prognosticating buried potential mineral deposits in virgin areas of odisha and adjoining regions india using 3d euler s deconvolution technique on gravity data for detailed exploration in future abstract the paper deals with an attempt to draw a blue print of fast track mineral targeting at a reasonably cheap cost around odisha and adjoining regions india taking clues from known structural controls of ore deposits mineralogical lithological metamorphic histories actual as well as proven mineral deposits occurrences and assuming probable shape and size of ore deposits we have used 3d euler s deconvolution solutions on gravity data for locating different ore groups viz ferrous group base and noble metals diamond and gemstones over a virgin and buried terrain 3d euler s deconvolution solutions indicate that there are four sets of apparently unknown faults aligned in e w n s nw se and ne sw directions related to different tectonic events in addition to the above we mapped several circular to elliptical shaped structures taking guidelines from different controls of ore deposits for various kinds as mentioned above we have prognosticated several hitherto unknown areas for the search of the above minerals from the 3d euler s deconvolution solutions and known mineralized zones this is primarily an attempt to explore those areas which are otherwise written off forever as there are not sufficient clues available from either geological or geochemical data set or their synergy this concept of mineral targeting we believe will usher to new thinking hypothesis for the future researchers which is reasonably fast and economic

neogene kinematics of the transylvanian basin romania the transylvanian basin is a major sedimentary basin located in the eastern part of the european alpine orogenic system it has a sedimentary fill more than 5 km up to 8 km in some small areas thick of upper cretaceous to upper miocene deposits it represents the main gas producing province in romania and central eastern europe in this article we analyze seismic lines and structural data from the basin as well as from its northern eastern and southeastern borders these data indicate a tectonic origin for the neogene structures from the transylvanian basin these structures include 1 northeast and southwest dipping thrust faults and 2 east northeast and west northwest striking strike slip faults having normal or reverse slip secondary structures such as salt diapirs and folds are related to these faults structural data from the basin and its border indicate a neogene overall compressional transpressional regime having maximum principal stress oriented north to northeast daniel ciulavu received a diploma in geology and geophysics at the university of bucharest in 1989 and his ph d in geology at the vrije universiteit amsterdam netherlands in 1999 he worked two years for geasol s a romania in hydrogeology coal and alluvial gold exploration since 1991 he has been on the staff of the university of bucharest where he teaches the courses on structural geology in the department of geophysics and kinematic analysis for master s students corneliu dinu received a diploma in geology in 1966 and his ph d in 1976 at the university of bucharest romania after graduation he worked as field geologist for prospectiuni s a romania since 1970 he has been on the staff of the university of bucharest where he is professor of structural geology and basin analysis since 1990 he has served as the dean of sciences at the faculty of geology and geophysics university of bucharest alexandru szakacs received a diploma in geology in 1974 and his ph d in 2000 at the university of bucharest romania he is senior geologist at the romanian institute of geology he has 25 years of experience in studying the neogene volcanism of the carpathian pannonian area he has also worked on the neogene volcanism of the cordillera betica spain dorin dordea received a diploma in geology in 1974 at the university of cluj romania his field of activity is remote sensing he has worked in several areas in africa and romania since 1999 he has served as the chief geologist of prospectiuni s a bucharest romania he is now working on the application of remote sensing in mining exploration

stratigraphic evidence of holocene faulting in the mid continent the meers fault southwestern oklahoma stratigraphic relations and ten 14c ages show that movement occurred on the meers fault in late holocene time movement on the fault postdates the browns creek alluvium which began to be deposited between 14 000 and 13 000 yr b p and predates the east cache alluvium which was deposited between 800 and 100 yr b p surface warping along the fault led to local stream incision on the upthrown side of the fault and deposition of slopewash and fan alluvium on the down thrown side three 14c ages of charcoal and soil humus buried by fan alluvium indicate that faulting probably occurred between 1400 and 1100 yr b p the soil that formed in the fan alluvium is only slightly more developed than that in the east cache alluvium and the weak development of both soils indicates a geologically recent age that is consistent with the radiocarbon ages obtained for these deposits

understanding the kinematic evolution and genesis of a back arc continental sag basin the neogene evolution of the transylvanian basin abstract formation and evolution of back arc basins is related to the interplay between subduction and convergence velocities during the formation of an orogenic chain sedimentary basins lacking fault systems that are genetically associated can be locally observed in the hinterland of the main orogenic belt in the usual location of a back arc basin these are interesting features potentially driven by a number of contrasting mechanisms such as lithospheric traction forces driven by plate boundary processes lateral migration of lower crustal material during orogenesis or sub lithospheric processes such as the rapid retreat of subducted slabs the transylvanian basin is a miocene basin that evolved at the rear of the main carpathians arc during the subduction of a slab attached to stable europe the pannonian basin is a typical continental extensional back arc domain to the east transylvania accommodated up to 3 5 km of middle upper miocene sediments deposited in a period coeval with the shortening in the neighbouring carpathians the basin fill was subsequently exhumed and partly eroded when the carpathians collided with the european craton in late miocene times this was associated with contractional deformation and widespread salt diapirism that forms the bulk of miocene deformation observed inside the basin our study shows that no significant normal faults are present inside the basin that could have accommodated 3 5 km subsidence in terms of upper crustal extension furthermore the basin kinematics cannot be linked directly with any other mechanical process explaining the observed miocene subsidence therefore we discuss several mechanisms that may explain regional scale observations and we conclude that the miocene transylvanian basin most likely formed in response to an asymmetric simple shear extension assisted by erosion and or lower crustal flow the upper crustal effects were localized in the neighbouring pannonian basin

sarmatian biostratigraphy of a marginal sea in northern croatia based on calcareous nannofossils abstract calcareous nannofossils of the serravallian tortonian transition known as the sarmatian in the paratethys were obtained from northern croatia central paratethys the nannofossil biostratigraphy of the studied area included early sarmatian biohorizons the reliability of these and previous biohorizons was tested and the known biostratigraphic and magnetostratigraphic datums of the paratethys were compared with those from the adjacent mediterranean and beyond six out of sixteen bioevents were selected to define five subzones pnn6d pnn8b and crossover for the badenian sarmatian boundary variations in the index fossil datums between the paratethys and tethys provide a broad perspective on local versus regional and global impacts on the nannofloras the paratethys tethys gateways ptgs and their progressive geodynamical closure exerted a fundamental control on the salinity circulation patterns and climate of the area the global regression at the end of the badenian and the tectonic events associated with the badenian sarmatian transition also restricted the ptgs initiating acmes of calcidiscus pataecus and reticulofenestra pseudoumbilicus causing a small early sarmatian extinction event that occurred in coastal environments which are the most affected by short term environmental fluctuations stronger connections through the ptgs during the early mid sarmatian transition induced a transgression that brought deep dwelling discoaster species into the area the final closure of the ptg with the mediterranean which had been placed at the badenian sarmatian boundary actually occurred in the late sarmatian as a result of tectonic movements that caused shallowing and a drastic reduction in nannofossil biodiversity the ptg with the indian ocean existed until the early tortonian which allowed an early but brief occurrence of small warm water ceratoliths

role of unconformity bounded units in the stratigraphy of the continental record a case study from the late miocene of the western pannonian basin hungary

putative greigite magnetofossils from the pliocene epoch greigite crystals of bacterial origin are widespread in modern sedimentary environments but their occurrence in the fossil record remains controversial grains from romanian pliocene aged sediments have now been identified as bacterial in origin tentatively placing them among the oldest known greigite magnetofossils

a new concept in euler deconvolution of isolated gravity anomalies euler s homogeneity equation has been used to develop a new technique to interpret the gravity anomalies over some simple geometrical sources namely a finite horizontal line vertical line a finite vertical ribbon a semicircular dome basin and an isosceles triangle approximating an anticline syncline a linear over determined system of equations has been solved to compute the depth the horizontal location and the structural index all treated as free parameters the concept of a variable structural index provides better depth estimates and helps to identify the source geometry nomograms have been prepared to compute an additional model parameter namely the horizontal vertical extent of a line the vertical extent of a ribbon and the radius of a dome basin the efficacy of the proposed method has been evaluated using two real field examples

extending the astronomical polarity time scale into the miocene an astronomical time scale is presented for the late miocene based on the correlation of characteristic sedimentary cycle patterns in marine sections in the mediterranean to the 65 n summer insolation curve of la90 1 2 with present day values for the dynamical ellipticity of the earth and tidd dissipation by the moon this correlation yields ages for all sedimentary cycles and hence also for the recorded polarity reversals and planktonic foraminiferal and dinoflagellate events the tortonian messinian t m boundary placed at the first regular occurrence of the globorofuliu conomiozea group in the mediterranean is dated at 7 24 ma the duration of the messinian is estimated at 1 91 myr because the miocene pliocene boundary has been dated previously at 5 33 ma 3 the new time scale is confirmed by oar 3gar ages of volcanic beds and by the number of sedimentary cycles in the younger part of the mediterranean messinian

the moho in extensional tectonic settings insights from thermo mechanical models the lithospheric memory is key for the interplay of lithospheric stresses and rheological structure of the extending lithosphere and for its later tectonic reactivation other important factors are the temporal and spatial migration of extension and the interplay of rifting and surface processes the mode of extension and the duration of the rifting phase required to lead to continental break up are to a large extent controlled by the interaction of the extending plate with slab dynamics the finite strength of the lithosphere has an important effect on the formation of extensional basins this applies both to the geometry of the basin shape as well as to the record of vertical motions during and after rifting we demonstrate a strong connection between the bulk rheological properties of europe s lithosphere and the evolution of some of europe s main rifts and back arc systems the thermo mechanical structure of the lithosphere has a major impact on continental break up and associated basin migration processes with direct relationships between rift duration and extension velocities thermal evolution and the role of mantle plumes compressional reactivation has important consequences for post rift inversion borderland uplift and denudation as illustrated by poly phase deformation of extensional back arc basins in the black sea and the pannonian basin region

late cenozoic uplift in southern asia and the american west rationale for general circulation modeling experiments geologic evidence suggests significant increases in uplift rates and absolute elevation in several areas during the late cenozoic especially in the last 10 m y regions of major uplift include the tibetan plateau and himalayan mountains of southern asia and the sierra nevada colorado plateau basin and range rocky mountains and high plains of the american west uplift occurred at a scale large enough to affect regional and global climate in a number of ways several of which we evaluate by general circulation model experiments in accompanying papers

time calibration of sedimentary sections based on insolation cycles using combined cross correlation dating the gone badenian stratotype middle miocene paratethys vienna basin austria as an example cross correlation between insolation intensities and a combination of sedimentary characters is introduced to obtain precise time calibration of sedimentary cycles the first step is to transfer the section scale into ages using power spectra comparing the main periods with orbital cycles while in the second step the standardized values of sedimentary signals are cross correlated with the standardized insolation curve as an example for the applicability of the method we investigated calcium carbonate organic carbon in a 9 m sampled section from the historical badenian stratotype at baden sooss lower austria comparing courses of geochemical parameters between the historical stratotype and a nearby drilled 102 m scientific core resulted in continuation of the core section into the stratotype cross correlation between magnetic susceptibility ms combined with the negatively correlated calcium carbonate content of the drilled section on the one side and summer solar insolation at 65 northern latitude on the other resulted in an extremely significant correlation between 14 221 and 13 982 ma this is younger than the before estimated time frame 14 379 to 14 142 ma based on cross correlation between ms and the orbital 100 kyr eccentricity and 41 kyr obliquity cycles the direct continuation of the drilled section by the stratotype covering a time span of 17 7 kyr consequently dates the badenian stratotype between 13 982 and 13 964 ma therefore the upper limit of the stratotype assigned to the early badenian puts it close to the langhian seravallian boundary at 13 82 ma demonstrating the need for revising the badenian stratigraphic subdivision based on orbital cycles especially the middle badenian wielician substage

paleogeographic evolution of the late miocene lake pannon in central europe abstract the paleogeographic evolution of lake pannon within the pannonian basin is reconstructed with eight maps ranging from the middle miocene to the early pliocene the maps are based on the distribution of selected biozones and specific fossils and on complementary sedimentological and seismic information our reconstruction shows that the history of lake pannon can be divided into three distinct intervals an initial stage with low water level which resulted in isolation from the sea at about 12 ma and might have led to temporary fragmentation of the lake an interval of gradual transgression lasting until ca 9 5 ma and a long late interval of shrinkage and infilling of sediments that persisted into the early pliocene the deep subbasins of the lake formed during the transgressive interval in more basinward locations than the deep basins of the preceding sarmatian age the southern shoreline running parallel with the sava and danube rivers along the northern foot of the dinarides changed very little during the lifetime of the lake while the northern shoreline underwent profound changes

the age of the sarmatian pannonian transition in the transylvanian basin central paratethys abstract a marked paleoenvironmental change took place at the beginning of the late miocene in the central paratethys with dominantly marine sarmatian successions grading rapidly into mainly brackish pannonian deposits a long and excellently exposed section comprising the sarmatian pannonian transition has been investigated at oarba de mures in the transylvanian basin romania in this paper we focus on both radiometric and magnetostratigraphic dating to provide a chronology for the sarmatian pannonian transition in transylvania two volcaniclastic layers located approximately 40 m below the sarmatian pannonian transition yield excellent 40ar 39ar ages the weighted mean plateau age for biotite and sanidine separates provided isotopic ages of 11 62 0 12 ma and 11 65 0 13 ma this implies deposition during the magnetic chron c5r 2r which is in agreement with the magnetostratigraphic results of the oarba de mures composite section rock magnetic analyses indicate greigite as the main magnetic carrier with characteristics very similar to the magnetosomal greigite found in the carpathian foredeep the newly obtained chronology at oarba de mures constrains the age of the sarmatian pannonian transition in the transylvanian basin to 11 3 0 1 ma slightly younger than the 11 61 ma postulated in the styrian and vienna basins

completing the neogene geological time scale between 8 5 and 12 5 ma a much improved high resolution magnetostratigraphy is presented for the interval between 8 5 and 12 5 ma in the deep marine astronomically tuned monte dei corvi beach section in northern italy this section contains the formally designated boundary between the middle and upper miocene defined by the tortonian gssp the natural remanent magnetization is carried by an unusual low temperature component of primary origin according to interpretations of isothermal remanent magnetization irm acquisition curves the palaeomagnetic signal is most probably carried by iron sulphides such as greigite or pyrrhotite the resultant magnetostratigraphy is reliable and can be straightforwardly calibrated to the astronomically tuned neogene time scale atnts2004 showing that the section ranges from chron c5an 2n up to c4 2r 1 the inferred correlation of the tortonian gssp to the older part of chron c5r 2n is confirmed thereby guaranteeing global correlation potential in addition the monte dei corvi beach section has been re tuned to the new numerical solution la2004 for the interval between 8 5 and 12 9 ma this exercise shows that the characteristic cycle patterns are not consistent with a single solution with fixed values for dynamical ellipticity and tidal dissipation for the younger part of the section sedimentary cycles show an excellent fit with intricate details of precession obliquity interference in the nominal la2004 1 1 solution however this solution produces serious mismatches between the sedimentary cycles and the precession obliquity interference in the interval older than 10 2 ma for this interval changes in tidal dissipation value while keeping dynamical ellipticity constant at its present day value are necessary to maintain a perfect fit a detailed visual comparison reveals a very good to excellent fit with la2004 1 1 2 and to lesser extent with la2004 1 0 5 however la2004 1 1 2 is the preferred tuning target for the moment in the interval older than 10 2 ma the astronomical re tuning on precessional scale to la2004 1 1 yielded slightly different astronomical ages for each basic cycle and hence also for the calcareous plankton events and magnetic reversal boundaries with uncertainties ranging within a few thousand years the age of the tortonian gssp turns into 11 625 ma instead of the previously published 11 608 ma our ages should replace existing ages in the astronomically tuned neogene time scale atnts2004

magnetite dissolution diachronous greigite formation and secondary magnetizations from pyrite oxidation unravelling complex magnetizations in neogene marine sediments from new zealand detailed rock magnetic and electron microscope analyses indicate that the magnetic signature of neogene marine sediments from the east coast of new zealand is dominated by the authigenic iron sulphide greigite the greigite is present as a mixed population of stable single domain and superparamagnetic grains which is consistent with authigenic growth from solution this growth can result from pyritization reactions soon after deposition which also leads to dissolution of most detrital magnetite however where constrained by field tests our data suggest that remanence acquisition can occur 1 myr after deposition and can vary in timing at the outcrop scale strong viscous overprints result from oxidation of the iron sulphides probably during percolation of oxic ground water this process can sometimes destroy any ancient remanent magnetization this complex magnetic behaviour particularly the presence of late forming magnetizations carried by greigite means that the remanence in new zealand cenozoic sediments and in similar sediments elsewhere cannot be assumed to be primary without confirmation by field tests the reversals test should be employed with caution in such sediments as patchy remagnetizations can lead to false polarity stratigraphies

forcing of late cenozoic northern hemisphere climate by plateau uplift in southern asia and the american west geologic evidence indicates that net vertical uplift occurred on a large kilometer scale and at accelerating rates during the middle and late cenozoic in plateaus of southern asia and the american west based on this evidence general circulation model sensitivity tests were run to isolate the unique effects of plateau uplift on climate the experiments simulated significant climatic changes in many places some far from the uplifted regions the basic direction of most of these simulated responses to progressive uplift is borne out by changes found in the geologic record winter cooling of north america northern europe northern asia and the arctic ocean summer drying of the north american west coast the eurasian interior and the mediterranean winter drying of the north american northern plains and the interior of asia and changes over the north atlantic ocean conducive to increased formation of deep water the modeled changes result from increased orographic diversion of westerly winds from cyclonic and anticyclonic surface flow induced by summer heating and winter cooling of the uplifted plateaus and from the intensification of vertical circulation cells in the atmosphere caused by exchanges of mass between the summer heated and winter cooled plateaus and the mid latitude oceans disagreements between the geologic record and the model simulations in alaska and the southern rockies and plains may be related mainly to the lack of narrow mountain barriers in the model orography taken together the observed regional trends comprise much of the pattern of late cenozoic climatic deterioration in the northern hemisphere that culminated in the plio pleistocene ice ages the success of the uplift sensitivity experiment in simulating the correct pattern and sign of most of the observed regional climatic trends points to uplift as an important forcing function of late cenozoic climatic change in the northern hemisphere at time scales longer than orbital variations however the modest amplitude of the uplift induced cooling simulated at high latitudes indicates a probable need for additional climatic forcing

the mid langhian flooding in the eastern central paratethys integrated stratigraphic data from the transylvanian basin and se carpathian foredeep the mid langhian badenian flooding fully reconnected the semi isolated central paratethys realm with the mediterranean and thereby drastically changed the middle miocene paleogeography of central europe due to the scattered stratigraphic record and scarcity of independent age constraints in some areas the precise age and underlying mechanism are still debated we present integrated chronostratigraphic data from five sections in the eastern part of the system to reconstruct the flooding event distal from the strait to the mediterranean by applying modern mediterranean biochronology planktonic foraminifera and calcareous nannofossils supplemented by an 40ar 39ar age on a tuff we demonstrate that the widespread open marine settings in the nw transylvanian basin were definitely installed after 14 9 ma mmi4d biozone and in most areas before 14 4 ma in the marginal study area in the se carpathian foredeep fully marine conditions likely set in slightly later 14 6 14 4 ma there short lived marine incursions into the brackish environment occurred since the latest burdigalian pre flooding phase the new ages overlap with the flooding in the majority of the central paratethys 14 9 14 4 ma and with marine overflow into the black sea 14 85 ma we suggest that the transgression was driven by subsidence of the pannonian basin by creating accommodation space and diminishing barriers between sub basins but was likely enhanced by a global sea level rise finally we speculate that the scarcity of all calcareous material in the se carpathian foredeep before the mid langhian flooding might be related to pulses of nutrient rich brackish and low ph water from the neighboring black sea basin

vertical density contrast and mapping of basement conrad and moho morphologies through 2d spectral analysis of gravity data in and around odisha india abstract power spectrum analysis of complete bouguer anomaly cba map of eastern ghat mobile belt egmb and its surroundings in india through two dimensional 2d spectral analysis has provided estimates of the ensemble average depths for the density discontinuities which represent crustal inhomogeneities the spectral analysis method has helped to estimate the depths of a perturbing body sources which are obtained from the negative slopes of the linear relationship between the logarithmic power spectrum and the wave numbers of the gravity field the detailed analysis reveals three horizontal discontinuities i phanerozoic sediment thickness ii basement depth and iii conrad discontinuity the average thickness of phanerozoic sediments is estimated to be 3 km whereas depth of basement and conrad discontinuity are at 7 km and 14 5 km respectively additionally mohorovicic discontinuity also estimated at a depth of 32 8 km in the study region

forced regressions in a large wave and storm dominated anoxic lake rhaetian sinemurian kap stewart formation east greenland during rhaetian sinemurian time a large wave and storm dominated lake was situated in the jameson land basin east greenland lake deposits consist of alternating black unfossiliferous mudstones and sheet sandstones anoxic conditions dominated at the lake bottom during deposition of the muds and the water column was probably stratified the sandstones were deposited by progradation of wave and storm dominated deltas in a water depth of less than 15 m sequence stratigraphic interpretation suggests that the mudstones were deposited in periods of rising and very high stands of lake level whereas progradation of the deltaic sheet sandstones took place during forced regressions caused by significant falls the lake thus underwent a large number of fairly high amplitude changes in level probably caused by climatic fluctuations the high order cycles can be grouped into several long period cycles that show the same number of major fluctuations as published eustatic sea level curves this similarity suggests a causal link between eustasy and long period variations in the lake the kap stewart formation represents one of the few ancient examples of a large wave and storm dominated lake and it is probably the first documented case of abundant well developed lacustrine forced regressions

facies development along the tide influenced shelf of the burdigalian seaway an example from the ottnangian stratotype early miocene middle burdigalian abstract herein we report quantitative micropaleontological benthic foraminifers dinoflagellate cysts calcareous nannoplankton sedimentological grain size analysis and geophysical background gamma radiation analyses from ottnang schanze the stratotype for the regional ottnangian stage central paratethys lower miocene middle burdigalian the revealed trends in bathymetry primary productivity bottom water oxygenation and water energy allow exemplary insights into the paleoenvironment of the terminal burdigalian seaway several facies of a eutrophic environment are distinguished that reflect a transition from a suboxic outer neritic to upper bathyal towards a better oxygenated middle neritic setting under the influence of storm events and currents a comparison with available data from upper austria and bavaria consistently shows the regressive trend during the late early ottnangian in upper austria the deep water facies from the lower part of the stratotype represents the most distal sediments the upper part together with localities closer to the northern coast records inner to middle neritic environments that are heavily affected by tidal currents the facies distribution results from the progradation of a tide influenced environment along the northern shelf of the north alpine foreland basin heralding the closure of the burdigalian seaway the available age estimate for the stratotype constrains the onset of the regressive phase to 18 ma

integrated wide angle and near vertical subbasalt study using large aperture seismic data from the faeroe shetland region acquiring large aperture seismic data 38 km maximum offset along a profile crossing the faeroe shetland basin in the north atlantic enables us to use wide angle reflections and refractions in addition to conventional streamer data 0 6 km for subbasalt imaging the wideangle results are complemented and confirmed by images obtained from the conventional near vertical offset range traveltime tomography applied to the wide angle data shows a low velocity layer 3 5 4 5 km s underneath southeastward thinning lava flows suggesting a 2 5 3 0 km thick sedimentary layer the velocity model obtained from traveltime tomography is used to migrate wide angle reflections from large offsets that arrive ahead of the water wave cone the migrated image shows base basalt and sub basalt reflections that are locally coincident with the tomographic boundaries application of a new multiple suppression technique and controlled stacking of the conventional streamer data produces seismic sections consistent with the wide angle results prestack depth migration of the near vertical offsets shows a continuous base basalt reflection and a clearly defined termination of the basalt flows

biotic and abiotic response to palaeoenvironmental changes at lake pannons western margin central europe late miocene a multidisciplinary study was performed on a c 30 m thick limnic deltaic sequence in the styrian basin austria geophysical gamma ray activity rock magnetism geochemical organic carbon sulphur and sedimentological observations were combined with palaeontological information mainly ostracods on this base several ecological factors were deduced terrigenous influx salinity water depth and oxygenation based on integrated stratigraphy as well as on palaeomagnetic results the whole section is set to chron c5r 2r 1n 11 308 11 263 ma and covers a period of less than 45 kyr in addition to the long term record we analysed short term changes by high resolution sampling 5 mm sample interval ostracods magnetic susceptibility this 2 3 m thick interval spans in total 3500 yr with an individual sample resolution of a few years only the combination of these data permit the description of the palaeoenvironmental evolution of the section in detail at the base of the section the development of a conifer swamp on the lakeside of lake pannon is documented this almost freshwater swamp existed for some centuries before it became extinct within a few decades due to a rise of the water table the drowning is related to a transgression of lake pannon which triggered the establishment of a brackish water fauna as well as greigite formation in the lake sediments in general the ongoing transgression favoured benthic life due to increased salinity up to mesohaline conditions the high resolution ostracod and magnetic susceptibility record reflect short term fluctuations in bottom water ventilation these oscillations probably range in the order of centuries and decades and are possibly related to climatic shifts later the successive deepening of the lake resulted in a significant faunal turnover a meromictic system with a well established oxygen depleted hypolimnion developed finally the limnic phase was replaced by a prograding deltaic system where the amplified input of coarse grained material and freshwater also affected benthic life periodic changes in clay illite content were detected by the gamma ray log throughout the entire section the observed cycles 5 12 kyr of the gamma ray log may reflect a super ordinate modulation of the sedimentary record by climatically forced changes in precipitation or run off

benchmark data of a changing sea palaeogeography palaeobiogeography and events in the central paratethys during the miocene abstract the reconstruction and interpretation of terrestrial ecosystems and vegetational patterns in the central european miocene have to take into account the influence of a vast landlocked water body namely the paratethys sea as a northern appendage of the early mediterranean sea it spanned a north south gradient of at least 4 latitude and has been suggested to represent some kind of palaeothermometer which reflected slight expansions or restrictions of climatic belts due to its vulnerable marine connections it was also highly susceptible to major global sea level fluctuations which are reflected in phases of endemism hence a fairly continuous record of marine nearshore assemblages throughout the miocene reflects an extraordinary interplay of sea level fluctuations changes in climate immigrations and blooms in autochthonous elements whilst biostratigraphic implications of these patterns were recognised early in palaeontology a biogeographic model is still lacking the intermingling of palaeogeographic terms with those restricted to biogeography is still commonly used a situation which can be overcome by integrating data from different biota into a new palaeobiogeographic scheme herein a data set of 1809 species level taxa gastropoda and foraminifera serves as the base for interpretations gastropods in particular turned out to be of greatest value for the differentiation of palaeobiogeographic units due to sensitive reactions to all environmental parameters and occupying a wide range of ecological niches based on the excellent gastropod record the proto danubian province early danubian p danubian p balatonian p and a proto caspian subprovince are defined the biogeographic reorganisations are associated with five major biotic events within the gastropod faunas these big five comprise four extinctions the late ottnangian extinction event loee the mid badenian extinction event mbee the badenian sarmatian extinction event bsee the sarmatian pannonian extinction event spee and one exceptional immigration origination event termed the early badenian build up event ebbe foraminifera are less valuable for palaeobiogeographic purposes in the area and time slice studied endemisms are generally lower and turn over rates less dramatic they are however very useful for stratigraphic correlations with the mediterranean and atlantic areas this fairly well calibrated marine biostratigraphy of the central paratethys serves as stratigraphic backbone and control for continental stratigraphy

carbon sulfur iron relationships in sedimentary rocks from southwestern taiwan influence of geochemical environment on greigite and pyrrhotite formation the importance of the magnetic iron sulfide minerals greigite fe3s4 and pyrrhotite fe7s8 is often underappreciated in geochemical studies because they are metastable with respect to pyrite fes2 based on magnetic properties and x ray diffraction analysis previous studies have reported widespread occurrences of these magnetic minerals along with magnetite fe3o4 in two thick plio pleistocene marine sedimentary sequences from southwestern taiwan different stratigraphic zones were classified according to the dominant magnetic mineral assemblages greigite pyrrhotite and magnetite dominated zones greigite and pyrrhotite are intimately associated with fine grained sediments whereas magnetite is more abundant in coarse grained sediments we measured total organic carbon toc total sulfur ts total iron fet 1n hcl extractable iron fea and bulk sediment grain size for different stratigraphic zones in order to understand the factors governing the formation and preservation of the two magnetic iron sulfide minerals the studied sediments have low ts fea weight ratios 0 03 0 2 far below that of pyrite 1 15 which indicates that an excess of reactive iron was available for pyritization observed low ts 0 05 0 27 is attributed to the low organic carbon contents toc 0 25 0 55 which resulted from dilution by rapid terrigenous sedimentation the fine grained sediments also have the highest fet and fea values we suggest that under conditions of low organic carbon provision the high iron activity in the fine grained sediments may have removed reduced sulfur so effectively that pyritization was arrested or retarded which in turn favored preservation of the intermediate magnetic iron sulfides the relative abundances of reactive iron and labile organic carbon appear to have controlled the transformation pathway of amorphous fes into greigite or into pyrrhotite compared to pyrrhotite dominated sediments greigite dominated sediments are finer grained and have higher fea but lower ts we suggest that diagenetic environments with higher supply of reactive iron lower supply of labile organic matter and consequently lower sulfide concentration result in relatively high eh conditions which favor formation of greigite relative to pyrrhotite

gravity profile interpretation using the r parameter imaging technique with application to ore exploration abstract this paper describes a fast imaging technique the so called here the r parameter imaging technique for the interpretation of gravity data measured along profile the technique calculates the r parameter a statistical parameter called the correlation coefficient between the analytic signal of the measured gravity field and that of the synthetic response of an assumed interpretive model in the restricted class of spheres and cylinders the characteristic source parameters depth shape origin point of the gravity profile and amplitude factor of the model correspond to the maximum r parameter value the method has been verified on noise free numerical examples following that the accuracy of the method has been carefully assessed on both noisy numerical examples and numerical examples with interference effects finally the technique has been successfully applied to five field data examples from canada sweden and cuba for mineral exploration and it is found that the obtained results are in good agreement with those reported in the published literature

the myth of the brackish sarmatian sea the biota of the 1 5 ma period of the middle miocene sarmatian of the central paratethys lack stenohaline components this was the reason to interpret the sarmatian stage as transitional between the marine badenian and the lacustrine pannonian stages however our new data indicate that brackish water conditions could not have prevailed sarmatian foraminifera molluscs serpulids bryozoans dasycladacean and corallinacean algae as well as diatoms clearly indicate normal marine conditions for the entire sarmatian during the lower sarmatian however a sea level lowstand forced the development of many marginal marine environments during the late sarmatian a highly productive carbonate factory of oolite shoals mass occurrences of thick shelled molluscs and larger foraminifera as well as marine cements clearly point to normal marine to hypersaline conditions this trend is not restricted to the western margin of the pannonian basin system but can be observed in the entire central and even eastern paratethys

strong evidence for the influence of solar cycles on a late miocene lake system revealed by biotic and abiotic proxies the late miocene paleogeography of central europe and its climatic history are well studied with a resolution of c 106 years small scale climatic variations are yet unresolved observing past climatic change of short periods however would encourage the understanding of the modern climatic system therefore past climate archives require a resolution on a decadal to millennial scale to detect such a short term evolution a continuous 6 m core of the paleo lake pannon was analyzed in 1 cm sample distance to provide information as precise and regular as possible measurements of the natural gamma radiation and magnetic susceptibility combined with the total abundance of ostracod shells were used as proxies to estimate millennial to centennial scale environmental changes during the mid tortonian warm period patterns emerged but no indisputable age model can be provided for the core due to the lack of paleomagnetic reversals and the lack of minerals suitable for absolute dating therefore herein we propose another method to determine a hypothetic time frame for these deposits based on statistical processes including lomb scargle and redfit periodograms along with wavelet spectra several distinct cyclicities could be detected calculations considering established off shore sedimentation rates of the tortonian vienna basin revealed patterns resembling holocene solar cycle records well the comparison of filtered data of miocene and holocene records displays highly similar patterns and comparable modulations a best fit adjustment of sedimentation rate results in signals which fit to the lower and upper gleissberg cycle the de vries cycle the unnamed 500 year and 1000 year cycles as well as the hallstatt cycle each of these cycles has a distinct and unique expression in the investigated environmental proxies reflecting a complex forcing system hence a single proxy analysis as often performed on holocene records should be considered cautiously as it might fail to capture the full range of solar cycles

manganese scavenging and oxidation at hydrothermal vents and in vent plumes abstract hydrothermal vents provide a major source of dissolved mn ii to the oceans where concentrations range from 5 mm within the 350 c hot smokers to just above ambient seawater concentration in far field vent plumes the mn ii rich environments within warm vents and vent plumes provide a suitable habitat for mn ii oxidizing bacteria in order to compare rates of scavenging and oxidation of mn ii proximally within vent fields

evolution turnovers and spatial variation of the gastropod fauna of the late miocene biodiversity hotspot lake pannon abstract lake pannon constituted the biggest hotspot of biodiversity in the late cenozoic of europe comprising a total diversity of almost 600 gastropod species the gastropod fauna of this huge brackish system which existed over about seven million years from the late miocene to earliest pliocene within the pannonian basin system has been well documented by a great many of taxonomic works in contrast the faunal development within the lake has not been properly addressed from a statistical point of view the present investigation demonstrates that species were not homogeneously distributed across space and time generating uneven and temporally shifting patterns of species richness and degree of point endemism across the lake the faunal compositions of the time intervals analyzed were highly different contrasting simple species accumulation as suggested by the overall numbers shifting patterns of local diversity within the lake reflect changing paleo shorelines resulting from prograding river systems entering and successively diminishing the lake surface area as mainly herbivorous grazers and predominantly shallow water inhabitants the gastropods traced the moving shelf margins and vegetation belts accordingly producing the observed diversity shifts in addition each time interval is characterized by a high degree of provincialism which is considered to reflect high habitat diversity this claim is supported by the complex subaqueous topography and the presence of extensive delta plains produced by the incoming river systems a potential driver for provincialism might be the adaptation of species to distinct water depths and related parameters finally the notable differences among the faunal compositions of the upper pannonian strata and the succeeding lower viviparus beds especially regarding family level indicate an environmental turnover at the transition brackish water species are mostly replaced by typical freshwater elements indicating strong fluvial influence based on our results and latest stratigraphic data we conclude that the viviparus beds were deposited in a different environment replacing lake pannon in the southern pannonian basin in the early pliocene

ba ca evolution in water masses of the mediterranean late neogene 1 a mediterranean composite sedimentary record was analyzed for ba ca ratios on carbonate shells of orbulina universa planktonic foraminifer ba ca carb providing the opportunity to study and assess the extent of freshwater inputs on the basin and possible impacts on its dynamics during the tortonian to recent period a number of scanning electron microscope analyses and auxiliary trace element measurements mn sr and mg obtained from the same samples exclude important diagenetic effects on the studied biogenic carbonates and corroborate the reliability of ba ca carb ratios in foraminifera calcite as indicators of seawater source components during the studied interval a long term trend with ba ca carb values shifting from 7 to 3 mol mol 1 from the base of the tortonian to the top of the messinian is observed the interval of the late messinian salinity crisis where biogenic carbonates are missing or strongly diagenized represents a crucial passage not monitored in our record at the base of the pliocene up to about 4 7 ma the ba ca carb record shows a decreasing trend from 4 mol mol 1 stabilizing itself to an about constant value of 0 9 0 3 mol mol 1 for the whole plio pleistocene interval these results suggest a dramatic change in the continental runoff values up to 3 16 times higher during part of the late neogene tortonian early pliocene with a possible profound modification in the physical dynamics of the mediterranean basin first order mass balance equations used to estimate barium and salinity budgets in the mediterranean sea during the late miocene early pliocene interval support the hypothesis of an active connection of the basin with the paratethys region and of a definitive restriction at the base of the pliocene after about 0 7 ma from the well known messinian lagomare phase they also open intriguing scenarios on possible circulation shifts during the neogene

climatically influenced interactions between the mediterranean and the paratethys during the tortonian 1 the paratethys was a separate branch of the tethys ocean that developed as a series of inland seaways brackish lakes and wetlands within the interiors of central eastern europe and western asia during the oligocene neogene a short lived connection between the mediterranean sea and the paratethys continental realm toward the very end of the messinian salinity crisis is documented on the basis of the paratethyan affinity of the brackish shallow water faunas in several mediterranean localities nevertheless there are at present only a few comparative studies on stratigraphy paleobiogeography and paleoceanography of these two contiguous neogene provinces e g benson 2000 in this study we compare and integrate different stratigraphic data sets from middle upper miocene sequences of the central mediterranean and the western pannonian basins central paratethys that are seen as parts of a complex paleoclimatic and paleoceanographic system on the basis of this comparison we propose that the paratethys had a long lived influence on the large scale oceanographic circulation of the eastern mediterranean at least since the tortonian between 9 7 and 7 5 ma that is well before the onset of the messinian lagomare event 5 5 ma the integrated stratigraphy of coeval marine tortonian and continental transdanubian strata presented here suggests that mutual interaction and interdependence of climate subsystems ostensibly developed over the mediterranean area and central eastern europe continent and were orbitally forced long eccentricity insolation forcing is hypothesized to have exerted a broad control on the freshwater budget of the brackish pannonian basin and the consequent oceanographic setting of the mediterranean region

comparative sequence stratigraphy of low latitude versus high latitude lacustrine rift basins seismic data examples from the east african and baikal rifts abstract lakes baikal malawi and tanganyika are the world s three largest rift valley lakes and are the classic modern examples of lacustrine rift basins all the rift lakes are segmented into half graben basins and seismic reflection datasets reveal how this segmentation controls the filling of the rift basins through time in the early stages of rifting basins are fed primarily by flexural margin and axial margin drainage systems at the climax of syn rift sedimentation however when the basins are deeply subsided almost all the margins are walled off by rift shoulder uplifts and sediment flux into the basins is concentrated at accommodation zone and axial margin river deltas flexural margin unconformities are commonplace in the tropical lakes but less so in high latitude lake baikal lake levels are extremely dynamic in the tropical lakes and in low latitude systems in general because of the predominance of evaporation in the hydrologic cycle in those systems evaporation is minimized in relation to inflow in the high latitude lake baikal and in most high latitude systems and consequently major sequence boundaries tend to be tectonically controlled in that type of system the acoustic stratigraphies of the tropical lakes are dominated by high frequency and high amplitude lake level shifts whereas in high latitude lake baikal stratigraphic cycles are dominated by tectonism and sediment supply variations

the shutdown of an anoxic giant magnetostratigraphic dating of the end of the maikop sea abstract paratethys the lost sea of central eurasia was an anoxic giant during oligocene early miocene maikop series times with a size matching the modern day mediterranean sea and a history of anoxic conditions that lasted for over 20 myrs the eastern part of this realm black sea caspian sea domain holds key records for understanding the build up maintenance and collapse of anoxia in marginal seas here we show that the collapse of anoxic maikop conditions was caused by middle miocene paleogeographic changes in the paratethys gateway configuration when a mid langhian badenian tarkhanian transgression flooded and oxygenated the eastern paratethys we present an integrated magneto biostratigraphic framework for the early middle miocene tarkhanian chokrakian karaganian regional stages of the eastern paratethys and date the lithological transition from anoxic black shales of the maikop series to fossiliferous marine marls and limestones of the regional tarkhanian stage for this purpose we selected two long and time equivalent sedimentary successions exposed along the belaya and the pshekha rivers in the maikop type area in ciscaucasia southern russia we show that a significant but short marine incursion took place during the tarkhanian ending the long lasting maikop anoxia of the basin our magnetostratigraphic results reveal coherent polarity patterns which allow a straightforward correlation with the time interval 15 12 ma of the geomagnetic polarity time scale the tarkhanian flooding occurred during a relatively short normal polarity interval that correlates with c5bn resulting in an age of 14 85 ma the regional tarkhanian chokrakian stage boundary is located within c5adn at an age of 14 75 ma and the chokrakian karaganian boundary is tentatively correlated with c5acn and an age of 13 9 13 8 ma our new tarkhanian flooding age reveals a paleogeographic scenario that is different from many previous reconstructions instead of envisaging marine connections to the indian ocean we show that major changes in connectivity between the eastern and central paratethys seas have caused the influx of marine waters during the tarkhanian an increase in marine connectivity with the mediterranean during a short episode of rapid sea level rise triggered mixing and ended the widespread anoxia in the eastern paratethys the mixing episode was short lived 100 kyr as the sea level rise slowed down and connectivity degraded because of tectonic uplift in the gateway area

african monsoons an immediate climate response to orbital insolation the croll milankovitch astronomical theory of climate1 3 has received strong support from the evidence of a linear climatic forcing by obliquity and precession although nonlinearity had to be assumed for eccentricity4 5 moreover interglacials have appeared to be controlled by the orbital insolation6 although a phase shift of 6 000 5 000 yr is seen between an astronomical climate index and terrestrial climate indicators dominated by the northern ice sheet dynamics climate proxy data of low latitudes are less directly dependent on the ice sheets here it is shown that during the past 464 000 yr african monsoons signalled by the east mediterranean sapropels were heaviest always and only when a northern summer monsoon index computed from the orbital variation of insolation reached maximum values this occurred during all the interglacials but also twice during glacial periods thus tropical aridity is not the single climatic pattern of glacial periods an immediate terrestrial climate response to orbital variations of insolation is established

stress induced late stage subsidence anomalies in the pannonian basin abstract subsidence sedimentation and tectonic quiescence of the pannonian basin was interrupted a few million years ago by tectonic reactivation this recent activity has manifested itself in uplift of the western and eastern flanks and continuing subsidence of the central part of the pannonian basin low to medium magnitude earthquakes of the carpathian pannonian region are generated mostly in the upper crust by reverse and wrench fault mechanisms there is no evidence for earthquakes of extensional origin 2 d model calculation of the subsidence history shows that a recent increase in magnitude of horizontal compressional intraplate stress can explain fairly well the observed quaternary uplift and subsidence pattern we propose that this stress increase is caused by the overall europe africa convergence in late pliocene consumption of subductible lithosphere at the eastern margin of the pannonian basin was completed and the lithosphere underlying the pannonian basin became locked in a stable continental frame consequently extensional basin formation has come to an end and compressional inversion of the pannonian basin is in progress

early diagenetic greigite as a recorder of the palaeomagnetic signal in miocene pliocene sedimentary rocks of the carpathian foredeep romania summary during the miocene pliocene the carpathian region represented the westernmost part of the so called eastern paratethys a palaeobioprovince that covered central and eastern europe as well as parts of southwest asia previous palaeomagnetic investigations provide a highresolution magnetochronology for the sedimentary sequences of the carpathian foredeep and indicate a marked transition in magnetic carriers from iron oxides to iron sulphides in chron c3r here we demonstrate using detailed rock magnetic investigations and scanning electron microscope sem analyses that the major magnetic iron sulphide mineral is greigite fe3s4 thermomagnetic runs indicate an irreversible decrease in magnetization with increasing temperature up to 400 c and sem observations indicate octahedral grain morphologies and fe s ratios that are indicative of greigite hysteresis loops have rectangular shapes which are typical of single domain behaviour with coercivity and coercivity of remanence at values of bc 35 45 mt and bcr 52 67 mt respectively first order reversal curve diagrams have contours that close around single domain peaks with bc values of 45 90 mt isothermal remanent magnetization component analysis reveals a small dispersion for the greigite component dispersion parameter dp 0 15 log units indicating a narrow grain size distribution a positive fold test inclination shallowing and two positive reversal tests are additional arguments for the syn depositional formation of this greigite we thus argue that most of the greigite was formed under early diagenetic conditions that is within 1000 yr of deposition of the sediment in this setting and that it thus can be considered as a reliable recorder of the palaeomagnetic signal in this situation the appearance of greigite during chron c3r between 6 0 and 5 5 ma in the carpathian foredeep is most likely related to regional tectonic and or climatic events that reshaped the basin configuration and changed the palaeoenvironmental conditions

gravity characterization of the la rioja valley basin argentina thelariojavalleyisasedimentarybasininthepampean ranges a region of basement uplifts and broad valleys in the andean foreland the present study advances understanding ofthegenesisofthebasinbyprovidingsubsurfacedataonits geometry and characteristics gravity and topographic data including a newly completed gravity survey were integrated tocreateacompletebougueranomalymap eulerandwerner deconvolution techniques sum with traditional potentialfieldsmethodsandsparseindependentdatafromseismicand magnetotelluric methods to test and constrain the subsurface geophysical characterization of the la rioja valley basin the residual anomaly obtained through upward continuation was inverted to obtain the best 3d gravity model of the la riojavalley basin which shows the first order geometry ofthebasin thisrevealsthatthebasinisasymmetric withup to 6000 m of low density basinfill in a depocenter located in thewest centralsectorofthevalley second orderfeaturesof thebasinincludeasoutheast trendingbasementhigh likelya fault zone that subdivides the basin which has been revealed by a suite of analytical methods 3d model of depth to basement a 2d inverse model and werner deconvolution solutions

rise and fall of the paratethys sea during the messinian salinity crisis abstract extremely thick evaporite units were deposited during the so called messinian salinity crisis msc 5 96 5 33 ma in a deep mediterranean basin that was progressively disconnected from the atlantic ocean a crucial but still poorly understood component in messinian evaporite models is the connectivity between mediterranean and paratethys i e the former black sea domain inadequate stratigraphic correlations and insufficient age control for paratethys sediments have so far hampered a thorough understanding of hydrological fluxes and paleoenvironmental changes here we present a new chronology for the eastern paratethys by integrating biostratigraphic and paleomagnetic data from mio pliocene sedimentary successions of romania and russia we show that a major flooding event from the mediterranean surged the paratethys basins at the maeotian pontian boundary 6 04 million years ago this indicates that sea level in both mediterranean and paratethys was high at the beginning of the msc we argue in favor of changes in paratethys mediterranean connectivity to initiate the msc in combination with elusive tectonic processes in the gibraltar arc a subsequent fall of paratethyan water level closely coincides to the mediterranean isolation event corresponding in age to the glacial cycles tg12 14 5 60 5 50 myr in the latest messinian a major climate change towards more humid conditions produced a positive hydrological balance and likely a transgression in the paratethys although our stratigraphic resolution cannot exclude a possible relation to the pliocene flooding of the mediterranean here

paleomagnetism in lake pannon problems pitfalls and progress in using iron sulfides for magnetostratigraphy dating of upper miocene sediments of the pannonian basin hungary has proven difficult due to the endemic nature of biota scarcity of reliable radio isotopic data and generally inconsistent magnetostratigraphic results the natural remanent magnetization nrm is mostly residing in greigite fe3s4 which complicates nrm interpretation we reinvestigate the viability of these sediments for magnetostratigraphy using samples from recently drilled well cores paet 30 and paet 34 from the paks region significant intervals of the cores contain composite nrm behavior thermal demagnetization results include multipolarity m type samples consisting of a low temperature lt above 120 c a medium temperature mt and a high temperature ht component within distinct temperature ranges and all exhibiting dual polarities the lt and ht components have the same polarity and are antiparallel to the mt component rock magnetic and scanning electron microscopy results indicate that all magnetic components reside in authigenic greigite the lt and ht components represent the characteristic remanent magnetization and are of early diagenetic origin the mt component records a late diagenetic overprint alternating field demagnetization cannot resolve the individual components it yields polarities corresponding to the dominant component resulting in erratic polarity patterns interpretation of lt and ht components allows a reasonably robust magnetostratigraphic correlation to the geomagnetic polarity time scale with the base of paet 30 at 8 4 ma and its top at 6 8 ma average sedimentation rate of 30 cm kyr the base of paet 34 is correlated to 9 ma and its top to 6 8 ma average sedimentation rate of 27 cm kyr

astronomically forced teleconnection between paratethyan and mediterranean sediments during the middle and late miocene abstract a high resolution correlation between an orbital tuned middle and early late miocene record of the central paratethys and an astronomically calibrated mediterranean deep marine composite record is proposed the astronomical tuning of the sarmatian and pannonian sedimentary record in the vienna basin confirms that the beginning of the pannonian regional stage lower tortonian dated in this work at 11 42 my is very close to the miller event mi5 it coincides with a period of minimum amplitude in the 1 2 myr obliquity cycle which in the mediterranean marine record corresponds with a drastic change in the planktonic foraminiferal fauna in addition the warmer period between mi5 and mi6 corresponding to a maximum in the long term 2 3 myr eccentricity cycle coincides with a long interval of lignite deposition in the paratethyan realm the sedimentation pattern shown by high frequency cyclicity between lignite and normal sediments reflects a primary influence of 100 kyr eccentricity cycles on the sedimentation system of the central paratethys which corresponds with small and large scale sapropel clusters hierarchical organization in the mediterranean record the badenian sarmatian boundary astronomically dated at 13 32 myr does not coincide with a low amplitude variation in the 1 2 myr obliquity cycle and any mi events this orbital configuration is supported by the paleoclimatic and paleoecologic data of the late badenian and early sarmatian which both represent a warm temperate system with stagnant bottom water conditions finally the transitional phase from a temperate early sarmatian to a warmer late sarmatian associated with predominant carbonate sedimentation coincides with the glacio eustatic isotope event mi4 while the entire late sarmatian spans a complete 1 2 myr obliquity cycle

miocene connectivity between the central and eastern paratethys constraints from the western dacian basin abstract the dacian basin formed an important link between the central and eastern parts of the paratethys a chain of late tertiary inland seas and lakes this study presents constraints on miocene sea and lake level fluctuations in the dacian basin and on the connectivity between it and other paratethys basins based on the interpretation of seismic lines a micropalaeontological study and lithofacies analysis of a large number of outcrops it is shown that relative sea level fluctuations in the western part of the dacian basin during the middle miocene were primarily driven by tectonic activity in the nearby carpathian mountains from the maeotian late miocene onwards however tectonic activity was minor and relative sea level fluctuations were primarily driven by changes in basin connectivity and climate the connection between the central and eastern paratethys was broken at the end of the middle miocene leading to the development of an endemic fauna in the former but new data presented here suggest that isolation was not sustained completely as central paratethys species appeared in the dacian basin during the maeotian late miocene besides the isolation two falls in water level occurred in the basin during the latest miocene of these the intra pontian sea level drop is the best known we show however that this drop was preceded by a larger sea or lake level drop in the late sarmatian maeotian this latter event may have affected much larger parts of the paratethys and we recommend more study of the bordering basins the hypothesis that the connection between the dacian and central paratethys basins was located in the region where the danube river presently crosses the carpathians was tested but no supporting evidence was found

exploration for strategic placer mineral deposits in a fluctuating shoreline depositional environment and mineralogical characterization of the ne odisha coast placers india abstract systematic exploration for beach placer minerals has been undertaken in the chandipur area of the balasore district on the ne odisha coast of india beach and dune sands are ubiquitous along the 1 1 5 km wide nne trending coast forty three representative samples were collected from selected boreholes sampled by auger and dormer drilling at depths ranging from 6 0 m to 12 0 m detailed experimental studies show that the total heavy minerals thm grade of the study area varies from 0 4 to 11 2 with an average grade of 3 8 for the individual samples the upper 5 50 m sand column with a grade of 5 2 is most significant the heavy mineral assemblages in decreasing volumetric percentages are comprised of 55 ilmenite 25 sillimanite 11 pyriboles others pyroxene amphibole mica coated grains etc 5 9 rutile 1 5 leucoxene 1 2 garnet 0 5 zircon and 0 4 magnetite texturally elevated heavy mineral concentrations are drawn from 200 astm 75 m and 120 astm 125 m mesh size fraction the 40 astm 425 m size fraction contains lowest thm the overall concentration of heavy minerals shows variable distribution patterns from shore to littoral inland and the maximum concentration of thm is observed within the 1 5 m sandy surface horizon the present study also addresses the down core variation of heavy mineral assemblages and role of hydrodynamic conditions in the deposition of these wide ranging placer minerals the range of graphic mean sizes mz varies from 2 19 to 2 60 which corroborates the deposition of sediments in low energy condition in a fluctuating shoreline along the chandipur coast linear discriminant function analysis is predominantly indicative of diversity in the depositional features under aeolian conditions in a shallow marine environment cm and tractive current plots indicate that the sediments are mainly formed by graded suspension and without any rolling conditions in the beach subenvironment in a tractive current field both the perennial panchpara river and the ephemeral drainage systems dubdubi river played a dominant role in transporting and supplying sediment flux consisting of radioactive mineral monazite assemblages in the study area the present detailed exploration study reveals a new find of placer deposits with radioactive and non radioactive mineral assemblages formed from diverse sources

middle to late miocene sequence stratigraphy of the transylvanian basin romania abstract the history of middle to late miocene evolution of the transylvanian basin was determined by the bordering carpathian orogen evolution the tectonic events being well recorded by the sedimentary history the basin evolved in a back arc setting under a regional compressional stress field the major tectonic events produced during the late sarmatian and post pannonian were related to the reactivation of the pre badenian fault systems the transylvanian basin got uplifted after the late pannonian during the pliocene and at least 500 m of sedimentary cover was eroded based on seismic and well log interpretation core and outcrop sedimentology and microfauna eight sequences were defined the early middle miocene sequences are roughly synchronous to five 3rd order global sea level cycles most of the recognized sequence boundaries are enhanced by regional tectonic events the sedimentary evolution was also strongly influenced by salt tectonics active starting with the late sarmatian two sequences were identified in the lower badenian deposits the third sequence late early badenian to early mid badenian preserves information about deeper shelf settings the lowstand of the following sequence was responsible for the deposition of the salt formation late mid badenian an important lithostratigraphic marker in the sedimentary record of the basin in general the upper badenian deposits parts of the 4th and 5th sequences belong to deep marine submarine fan systems the sarmatian partially 5th 6th and partially 7th sequences was characterized by diverse salinity conditions stretching from brackish to hypersaline and by high tectonic instability which induced several significant relative sea level falls during that time deltaic north and fandeltaic east systems fed submarine fans stacked between salt related submarine heights channeled deep marine depocenters most of the pannonian deposits partially 7th and 8th sequences belong to submarine fan systems but shallower facies were also found in the western and eastern part of the basin

the tortonian reference section at monte dei corvi italy evidence for early remanence acquisition in greigite bearing sediments summary the reliability of primary natural remanent magnetization nrm signals in greigite bearing sediments has been frequently questioned here we show that the stable nrm in the deep marine middle to late miocene sediments at monte dei corvi northern italy is mainly carried by greigite combined rock magnetic experiments and scanning electron microscopy successfully enabled discrimination between two greigite populations one fine grained and relatively well dispersed greigite population grain size between 60 and 200 nm is most likely of magnetotactic origin the second greigite population with larger grain sizes typically 700 nm to 1 m is most likely of authigenic bacterially mediated origin and is related to post depositional sulphidization processes greigite is the main magnetic remanence carrier in the older part of the section 12 8 to 8 7 ma whereas greigite and fine grained presumably magnetotactic magnetite are present in the younger part of the section 8 7 to 6 9 ma similar remanent magnetization directions of the magnetite and greigite components and the likelihood of a magnetotactic origin suggests that the nrm is of syn depositional age we suggest that moderate methane seepage from the underlying sediments may have occurred that resulted in the preservation of pristine greigite this corroborates the reliability of the previously established magnetostratigraphy at monte dei corvi

on the formation and evolution of the pannonian basin constraints derived from the structure of the junction area between the carpathians and dinarides 1 the large number and distribution of rollback systems in mediterranean orogens infer the possibility of interacting extensional back arc deformation driven by different slabs the formation of the pannonian back arc basin is generally related to the rapid miocene rollback of a slab attached to the european continent a key area of the entire system that is neglected by kinematic studies is the connection between the south carpathians and dinarides in order to derive an evolutionary model we interpreted regional seismic lines traversing the entire serbian part of the pannonian basin the observed deformation is dominantly expressed by the formation of miocene extensional detachments and half grabens the extensional geometries and associated synkinematic sedimentation that migrated in time and space allow the definition of a continuous and essentially asymmetric early to late miocene extensional evolution this evolution was followed by the formation of few uplifted areas during the subsequent latest miocene quaternary inversion the present day extensional geometry changing the strike across the basin is an effect of the clockwise rotation of the south carpathians and apuseni mountains in respect to the dinarides our study infers that the carpathian rollback is not the only mechanism responsible for the formation of the pannonian basin an additional middle miocene rollback of a dinaridic slab is required to explain the observed structures furthermore the study provides constraints for the pre neogene orogenic evolution of this junction zone including the affinity of major crustal blocks obducted ophiolitic sequences and the sava suture zone

latest pannonian and quaternary evolution at the transition between eastern alps and pannonian basin new insights from geophysical sedimentological and geochronological data the transition zone between eastern alps and pannonian basin is a key area for the investigation of the interplay between regional uplift local tectonic subsidence and depositional environment our study area the western margin of the little hungarian plain is characterized by gentle hills plateaus and depressions of which several are filled by lakes including one of austria s largest and shallowest lakes lake neusiedl geological investigation is hampered by the scarcity of outcrops and thus direct observation of sedimentological or structural features is difficult despite a long research history in the area a consistent landscape evolution model considering all relevant constraints is lacking so far in this study we apply multidisciplinary methods to decipher the complex tectonic and fluvial depositional evolution of the region local data from shallow lake drilling and seismic investigation are combined with regional data from industrial seismics and core data to gain new insights into the latest pannonian late miocene and quaternary evolution shallow lake seismic data show the erosionally truncated pannonian sediments dipping and thickening toward southeast toward the modern depocenter of the little hungarian plain overlying quaternary fluvial sediments show a very similar thickening trend except for the area on the plateau north of the lake indicating ongoing subsidence in major parts of the basin drill cores from locations along the lake seismic lines were analyzed concerning their age mineralogy and heavy minerals and compared with outcrop samples from the surrounding plains and the plateau to derive indications on sediment provenance a key observation is the apparent lack of a significant gravel layer on top of the tilted pannonian sediments beneath lake neusiedl small scale faults can be observed in the lake seismic sections along with key sedimentary features significant differences of the current elevation of the top pannonian between the surrounding plains and the plateau indicate post pannonian normal faulting which is a key process in shaping the present day morphology of the region luminescence ages of samples from the quaternary fluvial gravels on top of the pannonian sediments are a significantly higher 300 ka compared to the gravels in the plain 102 11 and 76 8 ka suggesting ongoing tectonic subsidence

estimating drawdown magnitudes of the mediterranean sea in the levant basin during the lago mare stage of the messinian salinity crisis abstract the messinian salinity crisis 5 97 5 33 ma is one of the most dramatic sea level change events in the global geological record during this event marine connection between the atlantic ocean and the mediterranean sea was restricted and episodically blocked while division of the messinian salinity crisis to three major stages is well established and accepted the scale of sea level change at each stage is still debated the magnitudes of the mediterranean fluctuations throughout the messinian salinity crisis have implications for contemporary connectivity between the eastern and western mediterranean basins during the third stage of the messinian salinity crisis commonly known as the lago mare mediterranean sea level fluctuated repeatedly lago mare drawdowns in the eastern mediterranean were estimated earlier to vary between we propose that during the lago mare ravinement along a continuously regressing transgressing coastline abraded the upper continental margin offshore israel the mediterranean regressed to a depth of 380 550 m below present day mean sea level and the eroded strata were evacuated downslope and deposited basinward of this depth as wedge shape clastic complexes during relatively short intervals sea level receded to altitudes 100 m below the erosional surface these sea level recessions exposed a pronounced inflection in the slope gradient to sub aerial processes generating knickpoints and headward migration of incising gullies these gullies developed later into channels conduits for sediment bypass fan deltas were deposited off these channels outlets a major sea level fall towards the end of the messinian salinity crisis reached 630 900 m below present day mean sea level streams incised into the exposed tops of the clastic wedges and fan deltas additionally meteoric water dissolved evaporites within the clastic complexes and formed sinkholes and dolines during this interval the mediterranean sea level fell to below the depth of the sicily sill which separated the eastern and western mediterranean basins this finding reinforces previously proposed paradigms which suggested that the messinian salinity crisis was terminated by spillover events from the atlantic ocean to the western mediterranean basin and consequently from the western to the eastern basin

high frequency cyclicity in a miocene sequence of the vienna basin established from high resolution logs and robust chronostratigraphic tuning abstract a high resolution chronostratigraphic record established by w e paulissen s m luthi p grunert s coric m harzhauser geol carp 2011 that takes into account variations in sedimentation rates and temporal gaps caused by unconformities and faulting in a research borehole in the vienna basin was used to investigate the possible presence of orbital millennial and centennial periodicities the sedimentary sequence covers middle to late miocene shallow marine fluvio deltaic and lacustrine shales silt and sandstones deposited during the transition from a pull apart basin to the final infill in a compressional regime spectral analysis was performed on gamma ray logs and high resolution electrical borehole images using three different analytical methods over six suitable intervals where continuous and constant sedimentation was identified the significant periods were found to closely match the orbital cycles of precession obliquity and short eccentricity providing a solid basis for the analysis of potential sub milankovitch cycles the significant frequencies encountered at the millennial to centennial scale fell for 75 within a relatively narrow time period of 0 25 to 5 kyr with a concentration of peaks between 1 and 2 kyr 29 and 500 to 800 years 17 these periodicities relate closely to the millennial dansgaard oeschger and bond cycles and centennial scale climate cycles documented from the quaternary it is suggested that the high frequency cycles observed in the miocene of the vienna basin represent differences in grain size related to cyclic variations in regional precipitation

widespread occurrence of greigite in the sediments of lake pannon implications for environment and magnetostratigraphy abstract lake pannon was a large lake at the southern margin of the european plate which separated from the central paratethys at the sarmatian pannonian boundary and was filled completely with sediment during the pliocene the separation produced an endemic fauna that makes classical geological correlation problematic with sediments outside the lake magnetostratigraphic correlation could potentially solve the problem and several long cores from deep drillings have been analysed for polarity information in the course of these studies primary magnetite was assumed to carry the natural remanent magnetization nrm later when outcrops of dark grey clays and marls of lake pannon were sampled for palaeomagnetic investigations of tectonic processes greigite was discovered as the carrier of the nrm at several localities this motivated a systematic study of the fine grained sediments of lake pannon in order to identify the principal carriers of the nrm to relate them to depositional environments and to assess the importance of neoformation of magnetic minerals the concentration of magnetic minerals is low in the fine grained sediments of lake pannon this made extraction of the magnetic minerals impossible so they were identified with magnetic methods magnetic experiments suggest that greigite is the most common magnetic mineral in the lake pannon sediments magnetite when it occurs is often accompanied by pyrite haematite is rare the studied sediments represent three time intervals 11 9 3 ma 8 7 ma and 6 4 ma in the 11 9 3 ma sediments greigite occurs as an original early diagenetic magnetic mineral during this period the climate was warm and humid the lake was fairly deep and stratified high organic productivity resulted in oxygen depleted bottom waters burial was rapid due to intensive erosion from the surrounding carpathian and alpine mountains magnetite bearing sediments deposited during this period do not carry a coherent palaeomagnetic signal which suggests that the magnetite was neoformed the 8 7 ma sediments were deposited in sublittoral upper delta plain and swamp environments in humid conditions they are also greigite bearing during the third investigated time period 6 4 ma the climate was arid the lake was of low salinity and was restricted to the southern part of the pannonian basin these sediments were deposited in a distal environment low sedimentation rate the characteristic magnetic mineral of this period is magnetite which most probably has a detrital origin widespread greigite which is always of diagenetic origin suspected neoformation of magnetite in the older parts of lake pannon and occasionally opposite polarities connected to greigite and magnetite when they occur together in the present study are important for magnetostratigraphic interpretation they imply that detailed magnetic mineralogical investigations and documentation of the consistency of the nrms by working on fully oriented samples are essential in magnetostratigraphic studies of molasse sediments

styles of extension in the pannonian basin abstract structural interpretation of reflection seismic profiles reveals distinct modes of upper crustal extension in the pannonian basin while some subbasins in the pannonian basin complex show little extension planar rotational normal faults others are characterized by large magnitude of extension detachment faults metamorphic core complexes gravitational collapse of the intra carpathian domain combined with subduction zone roll back is thought to be the driving mechanism of the neogene back arc extension the very heterogeneously distributed extension is accommodated by transfer faults which bound regions characterized by different polarity direction or amount of extension in cross section these transfer faults are characterized by flower structures typical for strike slip faults seismic stratigraphic interpretations indicate that the non marine post rift sedimentary fill of the pannonian basin can be described in terms of sequence stratigraphy the exceptionally good seismic sequence resolution allows recognition of third order and also fourth order depositional sequences which may reflect the interplay of tectonics and eustasy and milankovitch scale climatic variations respectively

magnetostratigraphy and radio isotope dating of upper miocene lower pliocene sedimentary successions of the black sea basin taman peninsula russia abstract we present a new chronology for the upper miocene to pliocene deposits of the black sea basin based on high resolution magnetostratigraphic data coupled with 40 ar 39 ar dating from the 475 m long zheleznyi rog section on the taman peninsula russia this section comprises the stratigraphic interval of the khersonian to kimmerian regional stages of the eastern paratethys our magnetostratigraphic record is based on biogenic and early diagenetic greigite components and yields a magnetostratigraphic sequence of 8 polarity zones a volcaniclastic ash layer at the upper part of the khersonian is radio isotopically dated at 8 69 0 18 ma the age of the khersonian meotian transition arrives at 8 6 or 8 2 ma which is significantly younger than earlier estimates the new age has important consequences for the hipparion datum in the eastern paratethys and implies that all vallesian fossil sites are younger than 11 2 ma the meotian stage has a total duration of 2 2 to maximum 2 6 myr and is marked by multiple erosional events the end of the paratethys sea is dated at 5 5 ma when the black sea becomes isolated from the caspian sea the dacian basin and the mediterranean

three dimensional gravity inversion using simulated annealing constraints on the diapiric roots of allochthonous salt structures in the northern continental slope of the gulf of mexico large oil and gas reservoirs are often found beneath sheetlike allochthonous salt structures that are laterally extensive some of these salt structures retain their diapiric feeders or roots beneath them these hidden roots are difficult to image seismically in this study we develop a method to locate and constrain the geometry of such roots through 3 d inverse modeling of the gravity anomalies observed over the salt structures this inversion method utilizes a priori information such as the upper surface topography of the salt which can be delineated by a limited coverage of 2 d seismic data the sediment compaction curve in the region and the continuity of the salt body the inversion computation is based on the simulated annealing sa global optimization algorithm the sa based gravity inversion has some advantages over the approach based on damped least squares inversion it is computationally efficient can solve underdetermined inverse problems can more easily implement complex a priori information and does not introduce smoothing effects in the final density structure model we test this inversion method using synthetic gravity data for a type of salt geometry that is common among the allochthonous salt structures in the gulf of mexico and show that it is highly effective in constraining the diapiric root we also show that carrying out multiple inversion runs helps reduce the uncertainty in the final density model

high resolution analysis of upper miocene lake deposits evidence for the influence of gleissberg band solar forcing article i nfo a high resolution multi proxy analysis was conducted on a 1 5 m long core of tortonian age 10 5 ma late miocene from austria europe the lake sediments were studied with a 1 cm resolution to detect all small scale variations based on palynomorphs pollen and dinoflagellate cysts ostracod abundance geochemistry carbon and sulfur and geophysics magnetic susceptibility and natural gamma radiation based on an already established age model for a longer interval of the same core this sequence can be limited to approx two millennia of late miocene time with a resolution of 13 7 years per sample the previous study documented the presence of solar forcing which was verified within various proxies on this 1 5 m core by a combination of redfit spectra and gaussian filters significant repetitive signals ranged in two discrete intervals corresponding roughly to 55 82 and 110 123 years fitting well within the lower and upper gleissberg cycle ranges based on these results the environmental changes along the 2000 year late miocene sequence are discussed no major ecological turnovers are expected in this very short interval nonetheless even within this brief time span dinoflagellates document rapid changes between oligotrophic and eutrophic conditions which are frequently coupled with lake stratification and dysoxic bottom waters these phases prevented ostracods and molluscs from settling and promoted the activity of sulfur bacteria the pollen record indicates rather stable wetland vegetation with a forested hinterland shifts in the pollen spectra can be mainly attributed to variations in transport mechanisms these are represented by a few phases of fluvial input but mainly by changes in wind intensity and probably also wind direction such influence is most likely caused by solar cycles leading to a change in source area for the input into the lake furthermore these solar induced variations seem to be modulated by longer solar cycles the filtered data display comparable patterns and modulations which seem to be forced by the 1000 year and 1500 year cycles the 1000 year cycle modulated especially the lake surface proxies whereas the 1500 year cycle is mainly reflected in hinterland proxies indicating strong influence on transport mechanisms

morphotectonic configuration of cratonic gondwana depocentres of eastern india abstract the bouguer anomaly over parts of the intra cratonic gondwana grabens of eastern india namely the damodar valley the eastern deogarh the southern rajmahal and the western margin of the peri cratonic external foredeep of west bengal has been analysed in terms of subsurface geology and tectonics we have identified three new gondwana troughs under the tertiary cover and have unveiled the probable subcrop pattern of the concealed cretaceous trap and the underlying gondwana sediments the shoulders of these permo carboniferous rift basins are characterised by high gravity anomalies suggesting the occurrences of high density hybrid rock masses outcrops of such hybrid rocks archean mostly metabasic in composition are actually seen at several places along the different rift shoulders two dimensional gravity modelling indicates that these high density 2 90 gm cm3 masses occur as enclaves at shallow depths 0 5 3 0 km within the upper crustal layer we believe that these anomalous masses have played a key role in the evolution of the various gondwana rift basins by controlling their width and guiding their propagation the present study supports a deep mantle plume generated triple arm rift basin geometry for this sedimentological province

the messinian salinity crisis in the dardanelles region chronostratigraphic constraints abstract an intense controversy on chronostratigraphy of upper miocene lower pliocene deposits and the messinian salinity crisis in the dardanelles area led to a systematic investigation of calcareous nannoplankton content of 10 key sections representative of the most relevant regional kirazli and alcitepe formations our study shows clearly that the kirazli formation deposits predate the messinian salinity crisis while those of the alcitepe formation postdate this outstanding event which severely impacted the region as widely known around the mediterranean basin fluvial canyon cutting or gap in sedimentation linked to the peak of the messinian salinity crisis separates the two formations detailed palaeoenvironmental investigations based on the fluctuation and distribution pattern of dinoflagellate cysts pollen grains and calcareous nannoplankton allow us to reconstruct the regional palaeogeography before during and after the messinian salinity crisis the gathered data do not indicate any marine corridor between the eastern mediterranean sea and eastern paratethys through the marmara sea region at the time of the messinian salinity crisis

multiple mechanisms of remagnetization involving sedimentary greigite fe3s4 sedimentary greigite fe3s4 is being increasingly implicated as the carrier of late diagenetic remagnetizations in fine grained marine and terrestrial sediments we have conducted detailed scanning electron microscope observations on polished sections from such sediments coupled with elemental microanalysis to identify greigite and to characterize the mode of occurrence and the relationships between the observed greigite and other authigenic and detrital mineral phases this detailed observational work in conjunction with recently published work has enabled identification of several mechanisms for remagnetization involving greigite 1 neoformation of greigite on the surfaces of early diagenetic framboidal and nodular pyrite 2 greigite growth within cleavages of detrital sheet silicate grains 3 neoformation of greigite on the surfaces of authigenic clays smectite illite 4 greigite nucleation on the surfaces of siderite 5 greigite growth on the surface of gypsum that resulted from earlier oxidation of nodular pyrite many other mechanisms for greigite neoformation are conceivable the key variables are appropriate redox conditions for generation of sulphide and availability of iron from the dissolution of a wide range of possible reactive detrital and authigenic iron bearing minerals documentation of a wide range of mechanisms for neoformation of greigite provides compelling evidence that sediments containing greigite should be routinely suspected of remagnetization which will complicate or compromise studies of environmental magnetism and geomagnetic field behaviour

euler deconvolution using differential similarity transformations of gravity or magnetic anomalies euler deconvolution of gravity and magnetic anomalies can be used to estimate the coordinates of a simple point source and the level of a constant background in the deconvolved field by testing a series of structural indices by using differential similarity transformations dsts joint estimations of the source coordinates the structural index and the coefficients of a linear background trend become possible dsts calculated from the derivatives of the interpreted field depend on the position of a chosen central point of similarity with respect to the source position on this basis techniques for euler deconvolution of anomalous fields are presented the theoretical formulations of dst and the deduced sets of equations for euler deconvolution are tested and verified on model and field examples of magnetic anomalies caused by one point and two point sources such as thin and thick dikes semi infinite and finite sills contacts steps faulted beds etc the possibility of an optimum estimation of the structural index can be used to define a second acceptance criterion along with the criterion of relative standard deviations the joint application of these two criteria ensures the selection of reliable results the suggested dst techniques are suitable for initial rapid estimations of the source type depth and plane location they may be applied to either profile or gridded data acquired from onecomponent measurements as well as from gradient or three component measurements additional data on the density or magnetization of the sources are not necessary

neogene sequences in the pannonian basin hungary abstract the rifting in the extensional pannonian basin occurred in the middle miocene the subbasins within the pannonian system formed under the control of expansional tectonics during this time sequence stratigraphic analysis on well logs revealed a single third order synrift sedimentary sequence developed due to tectonically enhanced eustatic sea level change in shallow marine environments the pannonian basin became an isolated lake by its postrift phase during the middle late miocene boundary the first postrift sequence formed under peculiar conditions when the basin lost its marine connections and simultaneously a considerable differential subsidence began the large volume of freshwater input supplied by rivers and the rapid subsidence of the basement caused the basin to be a deep freshwater lake the lacustrine postrift infill was studied by sequence stratigraphy using seismic reflection well log and magnetostratigraphic data numerous unconformities can be revealed which represent relative lake level fluctuations of different magnitudes the water level and volume of the large inland lake was very sensitive to different effects the most important ones are lake water budget sediment influx and differential subsidence of the basement the style of extension and sedimentation show differences with respect to passive continental margins that are reflected in the sedimentary architecture a significant third order water level change has been discovered in the eastern part of the pannonian basin while the western side did not experience such a great change in lake level this fact gives credit to the view of different interplay of lake level influencing effects in different areas of the basin this major third order lake level change has been age dated using magnetostratigraphy and a very close match was found with the age of the mediterranean salinity crisis the pannonian basin offers the possibility to study the infilling style and stratigraphic evolution of an inland rifted basin detailed sequence analysis allows the recording of the apparent sea lake level motion which can be compared to those observed in the surrounding seas further tectono stratigraphic evaluations of the pannonian basin may reveal hidden facts on the nature of lake level fluctuations and contribute new data to the discipline of sequence stratigraphy

third order middle miocene early pliocene depositional sequences in the prograding delta complex of the pannonian basin abstract few studies exist in the geologic literature that show the distribution of seismic facies and depositional sequences within a lacustrine basin the pannonian basin of central europe offers a unique opportunity to evaluate the influence of the eustatic signal on lacustrine deposition seismic stratigraphie and sedimentological studies indicate that the middle miocene early pliocene infill of the transtensional pannonian basin was formed by large delta systems systematic sequence stratigraphie analysis of 6000 km of reflection seismic data and more than 100 hydrocarbon exploration wells in hungary allowed the identification of twelve third order sequence boundaries in the late neogene sedimentary fill this number of depositional sequences corresponds to that of the published global eustatic curve for this time period furthermore based on magnetostratigraphic and radiometric data the ages of these depositional sequences can be tentatively correlated with the global eustatic curve the pannonian basin became isolated from the world sea at the sarmatian pannonian 11 5 ma boundary and formed a large lake the stratal patterns and sedimentary facies of individual systems tracts within the lacustrine sequences display the same characteristics as marine depositional sequences the relatively low rate of thermal subsidence and the high rate of sediment supply resulted in a good sequence resolution within the third order sequences higher order sequences can be recognized with an average duration of about 0 1 0 5 ma

gamma ray spectrometry in the field radioactive heat production in the central slovakian volcanic zone we report 62 sets of measurements from central southern slovakia obtained using a modern portable gamma ray spectrometer which reveal the radioactive heat production in intrusive and extrusive igneous rocks of the late cenozoic central slovakian volcanic zone sites in granodiorite of the stiavnica pluton are thus shown to have heat production in the range 2 2 4 9 w m 3 this variability being primarily a reflection of variations in content of the trace element uranium sites in dioritic parts of this pluton have a lower but overlapping range of values 2 1 4 4 w m 3 sites that have been interpreted in adjoining minor dioritic intrusions of similar age have heat production in the range 1 4 3 3 w m 3 the main stiavnica pluton has zoned composition with potassium and uranium content and radioactive heat production typically increasing inward from its margins reflecting variations observed in other granodioritic plutons elsewhere it is indeed possible that the adjoining dioritic rocks hitherto assigned to other minor intrusions of similar age located around the periphery of the stiavnica pluton in reality provide further evidence for zonation of the same pluton the vicinity of this pluton is associated with surface heat flow 40 mw m 2 above the regional background on the basis of our heat production measurements we thus infer that the pluton has a substantial vertical extent our preferred estimate for the scale depth for its downward decrease in radioactive heat production being 8 km nonetheless this pluton lacks any significant negative bouguer gravity anomaly we attribute this to the effect of the surrounding volcanic caldera filled with relatively low density lavas masking the pluton s own gravity anomaly we envisage that emplacement occurred when the pluton was much hotter and thus of lower density than at present its continued uplift evident from the local geomorphology being the isostatic consequence of localized erosion the heat production in this intrusion evidently plays a significant role hitherto unrecognized in the regional geothermics

the oxygen and carbon isotope distribution in the mediterranean water masses abstract the oxygen and carbon stable isotope compositions of the present day mediterranean waters have been measured in order to evaluate their variability which is related to the specific climatic and hydrological conditions within the basin the experimental equation between the 18 o value and the salinity of water based on 300 measurements on surface intermediate and deep waters sampled during the vicomed 2 and 3 cruises in the western central and eastern mediterranean has a slope of 0 27 a value which is significantly lower than the slope of 0 45 as defined in the northeast atlantic ocean this difference in the 18 o salinity relationship which occurs immediately in the alboran basin is basically a characteristic of the climatic regime of the mediterranean i e of an excess evaporation over fresh water input the largest variations of these two parameters 18 o of water and 13 c of co 2 are observed in the surface waters mostly in the western mediterranean this evolution mirrors the progressive eastward restriction which separates the less evaporated and more productive western basins from the more evaporated and less productive eastern basins the intermediate waters constitute a homogeneous layer however their 18 o values decrease eastward by 0 35 at maximum due to progressive dilution by mixing with overlying and underlying water masses their 13 c values decrease also eastward by 0 35 at maximum due to an increasing input of nutrients issued from the regeneration of sinking organic particles the deep waters have similar 18 o values but slightly higher 13 c values often by less than 0 1 than the overlying intermediate waters indicating generally well ventilated conditions due to active winter convection

climatically driven sedimentary cycles in the late miocene sediments of the pannonian basin hungary abstract by detailed cycle analysis of marginal mostly delta plain facies successions of pannonian sediments the frequency of water level changes of the late miocene pannonian lake hungary can be identified cycle analysis is presented with the object of defining the orbital record preserved in the strata we use the bed thickness as input data for our cycle analysis statistical analysis revealed a slow upward increase of both the frequency and thickness of sand beds in the boreholes resulting from infilling of the lake by a basinward migration of the marginal facies cycles of different order were detected in the sediments the higher order cycles are very close to or are equivalent with the milankovitch climatic cycles 19 ka caused by precession 50 ka caused by obliquity and 400 ka is the longer period of eccentricity the longer 1 m y cycle is very poorly developed here it is probably the analogue of the 3rd order global climatic cycle cycle analysis suggests that one of the main controlling factors of the water level changes of the pannonian lake was high frequency climatic oscillations the long term climatic changes only had a faint impact on the sediments the record of the 3rd order water level changes is very subtle our results show that the water level changes followed the rhythm of that of the eustatic changes but being asynchronous to them i e at high sea level stage the pannonian lake level was low and vice versa