timing of structural events in the himalayan foothills of northwestern pakistan the attock cherat range forms the southern boundary of the peshawar basin and includes rocks transitional between metasediments of the lesser himalaya and foreland basin strata to the south the attock cherat range comprises three fault bounded structural blocks which are from north to south 1 precambrian metaclastic strata overlain by unfossiliferous limestone which is itself apparently overlain by paleozoic strata with the contact not exposed 2 unfossiliferous flysch of precambrian age overlain by cretaceous and paleogene marine strata and murree red beds at least in part of early miocene age and 3 unfossiliferous limestone argillite and quartzite correlated in part to paleozoic strata in the peshawar basin overlain by a tertiary sequence generally similar to that in block 2 farther south in the kala chitta range strata of triassic to eocene age occur in south verging folds and thin thrust sheets the similarity of the tertiary sequences in the kala chitta range and in blocks 2 and 3 demonstrates that the pre tertiary sequences were juxtaposed by faults prior to deposition of the paleocene lockhart limestone this may coincide with initial contact of the west northwest facing passive margin of india with eurasia or nearby microplates major late tertiary imbricate thrusting and folding took place prior to uplift of the attock cherat range and to deposition of peshawar intermontane basin fill of pliocene pleistocene age the peshawar basin formed as the kala chitta range was faulted south on the main boundary thrust mbt forcing siwalik foreland basins still farther south late quaternary deformation in the southern peshawar basin occurred along a seismically active zone of en echelon stepped left faulted pressure ridges that may reflect a subsurface ramp on the older mbt

cambrian stratigraphy of kashmir and its boundary problems abstract the biostratigraphy of the cambrian of kashmir based on trilobite assemblage zones and trace fossils has been attempted faunal gaps occur in lower part of lower cambrian upper lower cambrian lower middle cambrian and upper part of upper cambrian in the lower cambrian cruziana rusophycus and redlichia zones in the middle cambrian solenopleura tonkinella tonkinella anomocare anomocare bailiella and bolaspidella zones and in the upper cambrian chuangia and dikelocephalites zones are recognized the position of intrasystem boundaries is also discussed while the various taxa have lithological preferences and are not necessarily found in a continuous sequence an attempt has been made to interpret the ranges of different genera the affinities of the fauna with that of other cambrian basins of the world are discussed it is concluded that the bulk of the fauna is of a cosmopolitan nature

the messinian problem in the pannonian basin eastern hungary insights from stratigraphic simulations abstract earlier studies revealed a prominent unconformity in the messinian stratigraphic record of the lacustrine pannonian basin but it was unclear what factors were responsible for the formation of this unconformity and thus its origin remained controversial the problem was further complicated by the fact that stratal patterns in the messinian varied significantly along the paleo margins of the lake our study introduces quantitative stratigraphic simulations to analyze the role of subsidence sediment supply and lake level changes in the formation of the unconformity and the various architectural patterns that evolved in response to the messinian events the results suggest that a relative lake level fall occurred in the messinian accompanied and followed by tectonic inversion in several parts of the basin since the rate of tectonic subsidence and or uplift varied in space and time the size of the relative lake level fall varied significantly across the basin while various stratal architectural patterns formed in the same time interval the age of the unconformity was estimated based on seismic correlations with paleomagnetic chronozones to be between 5 6 ma which was refined by stratigraphic simulations galeacysta etrusca cysts were found in the unconformity which confirmed its late messinian age the surface is called the intra messinian unconformity imu in this paper seismic interpretations and simulations of stratal architecture led to the formulation of a basin fill model and identification of four stratigraphic architectural patterns related to messinian events including a major lake level fall and coeval and subsequent uplift events in certain parts of the basin

the evolution of the danube gateway between central and eastern paratethys se europe insight from numerical modelling of the causes and effects of connectivity between basins and its expression in the sedimentary record abstract the pannonian and dacic basins in se europe are presently connected by the danube river across the south carpathians to which they are in a back arc and foreland position respectively part of the paratethys realm during the neogene open water communication between the basins was interrupted by the late miocene uplift of the carpathians different mechanisms have been proposed for the formation of the danube gateway capture of the upstream lake or an upstream river or incision of an antecedent river estimates on its age range from late miocene to quaternary a related issue is the effect of the large mediterranean sea level fall related to the messinian salinity crisis on the paratethys subbasins specifically the isolated pannonian basin in a synthetic numerical modelling study using a pseudo 3d code integrating tectonics surface processes and isostasy we addressed the causes and effects of changes in connectivity between two large sedimentary basins separated by an elevated barrier specifically we aimed to find the expression of connectivity events in the sedimentary record in general and the consequences for the evolution of the pannonian dacic area in particular we studied a range of parameters including the geometry and uplift rate of the barrier downstream sea level change and lithosphere rigidity we found that changes in connectivity are expressed in the sedimentary record through their effect on base level in the upstream basin and supply in the downstream basin the most important factors controlling the response are the elevation difference between the basins and the upstream accommodation space at the time of reconnection the most pronounced effect of reconnection through lake capture is predicted for a large elevation difference and limited upstream accommodation space downstream increase in sediment supply is dependent on the latter rather than the reconnection event itself of the parameters we tested the rigidity of the lithosphere was found to be of major importance by its control on sediment loaded subsidence and generation of accommodation space a downstream sea level change is unlikely to induce capture but may affect the upstream lake level by enhancing incision in a pre existing gateway in the pannonian dacic region the mechanically weak continuously subsiding pannonian lithosphere allowed accommodation of significant volumes of continental sedimentation and as a consequence transfer of excess sediment to the downstream dacic basin was only gradual the messinian sea level fall in the dacic basin could have been recorded in the pannonian basin only if a connection between the basins already existed more detailed modelling of river incision taking into account lateral differences in erodibility in the south carpathians will be required to give better time constraints on the formation of the danube gateway

coastal evolution changes in sea level and molluscan fauna in northeastern argentina during the late quaternary abstract the northern argentine shoreline underwent a remarkable progradation during the last 6890 years equivalent to about 4000 km 2 the shoreline moved approximately 30 km seaward on the average two types of accretionary shorelines were formed high energy environments produced barrier islands and barrier spits which began to form approximately synchronously low energy environments located between those of high energy consisted of tidal flats and salt marshes four groups of molluscan species represent the high energy palaeoenvironments of the barrier islands and barrier spits the other fossils represent a low energy environment of tidal flats the formation of the barrier islands began 6000 years b p it ended 3500 years ago due to a slight fall in relative sea level of 1 5 m above m s l and subsequent formation of barrier spits seaward as a consequence a very rapid faunal change occurred in less than 5000 6000 years the dominant high energy fossil fauna was replaced by a modern low energy fauna over most of the area palaeoenvironmental changes were probably greater and more rapid during the high energy episode when the fossils were more varied than those living now in the same area at samborombon bay whilst along the oceanic coastal area the molluscan fauna increased in diversity to the more varied extant one

magnetic fingerprint of the late holocene inception of the rio de la plata plume onto the southeast brazilian shelf abstract measurement of changes in the assembly of magnetic particles in sediment records is useful both for paleoclimatic and paleoceanographic reconstructions and for assessing provenance and pathways of sediment transport in this study we provide detailed rock magnetic analysis along with scanning electron microscopy sem ti ca ratio and particle size distribution of the decarbonated fraction of sediments to trace terrigenous source changes during the last 6 cal kyr bp in core 7610 collected on the se brazilian continental shelf magnetic mineralogy data indicate a gradual shift between two distinct sources of sediments 1 dust from southern south america patagonia central western argentina and puna altiplano plateau and 2 sediments eroded from the weathered volcanics of parana basin these materials reached the continental margin off argentina and uruguay by different pathways and were transported northward by the brazilian coastal current bcc the chronology of events related to the environmental record of core 7610 indicates that between 6 and 4 7 cal kyr bp dry conditions over continental south america resulted in enhanced eastward eolian transport of the argentinean loess and a limited discharge of the rdlp river load into the atlantic ocean at this time the sedimentary magnetic fraction that reached the se brazilian shelf reflect predominantly loessic sources transported from the pampean terraces to the argentinean and uruguay shelves and then distributed northward by the shelf current system from 4 7 to 2 cal kyr bp the climate became gradually wetter over the continent and the contribution of oxidized phases from the weathered parana basin mainly from the basaltic and acidic volcanics started to become important this change in climate overlaps in time a with the late holocene sea level fall recorded along the se south american coast later from 2 up to 0 9 cal kyr bp even wetter conditions were prevalent in s and se south america and the rdlp sedimentary load became the main source of sediments transported to the se brazilian shelf by the bcc the magnetic record of core 7610 reported here together with other paleoenvironmental tracers palynology geochemistry and stable isotopes thus indicates that the inception of the rdlp plume onto the se brazilian shelf started as early as 4 7 cal kyr bp and has been strengthened since then mostly due to changes in precipitation over south america and to a smaller extent by sea level changes

the tethyan himalaya palaeogeographical and tectonic constraints from ordovician palaeomagnetic data abstract to test whether the tethyan himalaya were part of the northern margin of india in the early palaeozoic we have produced the first primary palaeomagnetic data bedding corrected declination 267 5 inclination 63 0 95 10 pole latitude 20 2 n longitude 28 6 e from low metamorphic grade ordovician red beds in the tethyan himalaya shian formation the palaeomagnetic data are of excellent quality and a statistically positive fold test combined with a comparison with late cambrian ordovician gondwana poles suggests a primary hematite bearing magnetization acquired between 470 and 500 ma this is in excellent agreement with stratigraphic faunal and provenance age estimates and the palaeomagnetic data demonstrate that the tethyan himalaya must have been located in proximity to the indian craton during early ordovician times and are therefore consistent with a continuous margin at that time the shian formation pole overlaps with 470 500 ma gondwana poles but an even better fit can be obtained by invoking a post ordovician clockwise rotation of 13 4 such a rotation is similar in both sense and magnitude to clockwise rotations recorded in primary triassic sequences as well as palaeogene palaeomagnetic overprint data from the tethyan himalaya rotations of the tethyan himalaya compared with cratonic india are thus probably all of post late eocene age triassic and early ordovician data do not imply any crustal shortening between tethyan himalaya and cratonic india however in the early ordovician india was rotated 90 compared with its present orientation and any enlargement of india would not be detected by palaeomagnetic data

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

multi proxy evidence of late quaternary environmental changes in the coastal area of puerto lobos northern patagonia argentina abstract a multidisciplinary approach involving geomorphology taxa composition of mollusks and taphonomy performed on bivalve shells linked to mineralogical and microstructural analyses provide evidence of late quaternary environmental changes in the coastal area of puerto lobos in northern patagonia digital elevation models dems showed a beach ridge system developed parallel to the coast indicating sea level variations during mis1 mis5e and earlier in the pleistocene these ridges can be correlated with other marine ridges along the patagonian coast showing a similar geomorphological pattern and similar temporal evolution in relation to faunal composition when comparing the pleistocene with the holocene the most relevant differences are the presence of tegula atra and mactra patagonica in the pleistocene sediments and a diversification of taxa in the holocene during the late holocene the coastal area of puerto lobos also recorded a faunal shift in which species belonging to the magellan province displaced the fauna of the argentinean province to the north probably in coincidence with the little ice age lia taphonomic analysis on glycymeris longior and venus antiqua shells two common taxa in these beach ridges indicate greater energy in the depositional environment correlated with the youngest holocene beach ridge these shells exhibited taphonomic differences between them in relation to fracturing explained on the basis of higher elasticity in the g longior shell than in v antiqua shell because of its crossed lamellar microstructure

influence of the changing lunar orbit on the astronomical frequencies of pre quaternary insolation patterns the sensitivity of the frequencies of the earth s orbital elements involved in the astronomical theory of paleoclimates obliquity and climatic precession to the earth moon distance and consequently to the length of the day and to the dynamical ellipticity of the earth is investigated for the last billions of years but the new frequencies have been computed for the last 440 million years only a time interval over which data and a model of the earth were available moreover we consider only the impact of the changing precessional parameter assuming that the fundamental frequencies of the planetary motion are steady at the geological time scale under such hypotheses the shortening of the earth moon distance and of the length of the day back in time induces a shortening of the fundamental astronomical periods for obliquity and precession a shortening that is larger for longer periods

a critical review of mid to late holocene sea level fluctuations on the eastern brazilian coastline abstract the eastern coast of brazil is 7000 km long and has been the subject of systematic paleo sea level investigations for more than 35 years more than 1000 samples have been radiocarbon dated and paleo sea level trends have been determined for 14 coastal sectors these trends have in common a mid holocene sea level maximum pmt above present sea level and a subsequent fall to the present time the time and elevation of the pmt the time when relative sea level rose above present mean sea level and the nature of late holocene sea level fall can however differ significantly discrepancies are observed not only between neighboring coastal sectors but also between different studies in a same coastal sector this paper discusses all the key radiocarbon dated samples used to establish regional trends in relative sea level on the eastern coast of brazil it is concluded that although many of the key sea level indicators are imprecise in time and space there is widespread evidence 30 of the data set for a progressive decline possibly with uneven rates of relative sea level since the end of the pmt

the post last glacial maximum transgression in the de la plata river and adjacent inner continental shelf argentina abstract deposits resulting from the last glacial maximum transgression have been studied in the lowermost regions of the del plata fluvial basin in eastern argentina which include the de la plata river and adjacent inner shelf and coastal plains after applying the concepts of sequence stratigraphy those deposits were considered as a unit and defined as a depositional sequence composed of two systems tracts respectively representing the transgressive event and the highstand of sea level the sequence was deposited in different but genetically linked depositional environments such as high and low energy coasts with coastal barriers beach ridges coastal plains estuaries and deltas as well as inner shelf the boundary between the sequence and the underlying pre transgressive units is represented by the transgressive surface or unconformity modeled by the ravinement process which extends from the outer edge of the shelf to the coast this surface is time transgressive and can be recognized by distinct physical characteristics above and below it depending on the successive sedimentary environments developed in deep shallow or coastal waters as sea level fluctuated

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

geochemistry and arsenic behaviour in groundwater resources of the pannonian basin hungary and romania abstract groundwater resources in the pannonian basin hungary romania croatia and serbia are known to contain elevated naturally occurring as published estimates suggest nearly 500 000 people are exposed to levels greater than the eu maximum admissible concentration of 10 g l in their drinking water making it the largest area so affected in europe in this study a variety of groundwaters were collected from romania and hungary to elucidate the general geochemistry and identify processes controlling as behaviour concentrations ranged from so 4 2 reduction containing low as levels so 4 2 ongoing so 4 2 reduction will release s2 removing as from solution either by the formation of as sulfides or from sorption onto fe sulfide phases in methanogenic waters as released by reductive dissolution is not removed from solution and can rise to the high levels observed levels of organic c are thought to be the ultimate control on the redox conditions in these 2 groups high levels of organic c as found in group 1 would quickly exhaust any so 4 2 present in the waters driving the system to methanogenesis and subsequent high levels of as group 2 has much lower concentrations of organic c and so so 4 2 is not exhausted therefore as levels in waters of the pannonian basin are controlled not by release but by retention mechanisms ultimately controlled by levels of toc and so 4 2 in the waters d and 18o analysis showed that groundwaters containing elevated as dated mostly from the last ice age and are sourced from late pliocene to quaternary aquifers the importance of toc and retention capabilities of so 4 2 reduction have only previously been suggested for recent holocene sediments and groundwater most notably those in se asia as these are the most likely to contain the right combination of factors to drive the system to a redox situation leading to high aqueous as concentrations in contrast it is shown here that a much older system containing as bearing fe oxides also has the potential to produce elevated levels of as if the toc is suitable for the microbial population to drive the system to the correct redox situation and so 4 2 is either absent or wholly consumed

sea level fluctuations during the last 8600 years in the de la plata river argentina abstract the de la plata river considered from the geomorphologic point of view can be defined as a unit composed of a set of features genetically linked together which were formed as a result of the post last glacial maximum transgression regional stratigraphical morphological and topographical studies carried out in the de la plata river and surrounding areas of eastern argentina determined that the holocene evolution of the area was the result of processes resulting from relative sea level fluctuations in order to date the different stages of evolution a curve of sea level fluctuations was constructed after a selective choosing of samples with reliable ages supported by field geological evidence the curve shows a rapid initial transgressive event and the maximum highstand of mean sea level at 6000 yr bp at a relative elevation of 6 5 m above present the following regressive event was characterized by a discontinuous fall in sea level geomorphological evidence suggests that sea level fall could have experienced minor changes in rate as well as moments of stability that are not shown by the curve short interruptions in the geological record can be explained either by the same minor changes in sea level or by a change in wave regime correlation of transgressive regressive events with paleoclimatic and biogeographic information proposed that holocene sea level fluctuations in the de la plata river were mainly controlled by climatic changes

rotational overthrusting of the northwestern himalaya further palaeomagnetic evidence from the riasi thrust sheet jammu foothills india abstract thermal demagnetization results 316 samples are presented for the tertiary succession of the riasi thrust sheet jammu foothills northwestern himalaya primary and secondary magnetization directions of murree group red beds miocene to upper eocene sampled northeast of jammu indicate for this part of the riasi thrust sheet a clockwise rotation over about 45 with respect to the indian shield since late eocene early miocene time this accords with clockwise rotations of similar magnitude observed in the panjal nappe and the krol belt and is interpreted as representative for the northwestern himalaya results from the western part of the kalakot inlier sampled northwest of jammu i e basal murree claystone middle eocene and carbonate from the subathu group lower middle to lower eocene indicate an aberrant 20 25 counterclockwise rotation which is of local importance only available observations on rotation of himalayan thrust sheets with respect to the indian shield indicate that the himalayan arc has formed through oroclinal bending this supports powell and conaghan s and veevers et al s model of greater india with large scale intracontinental underthrusting along the main central thrust beneath the tibetan plateau minimal magnitudes of underthrusting of 550 km in the krol belt and 650 km in the thakkhola region are concluded palaeolatitude observations herein and in 1 agree with absolute positioning of the indian plate based on india africa relative movement data fixed to a hotspot frame in the atlantic ocean and with palaeolatitude observations from dsdp cores on the indian plate collision related secondary magnetic components observed both to the north and to the south of the indus tsangpo suture zone show palaeolatitudes between the equator and 7 n comparison of both datasets indicates that initial contact between greater india and south central asia had been established in the hindu kush karakorum region by about 60 ma ago whereas eastwards progressive suturing had advanced to the lhasa block segment of the indus tsangpo suture zone before 50 ma ago

warmer or cooler late holocene marine palaeoenvironments interpreting southeast australian and brazilian sea level changes using fixed biological indicators and their δ18o composition abstract relic inter tidal assemblages of sessile organisms which are referred to as fixed biological indicators fbis are shown to be useful proxies for late holocene climatic and environmental changes as well as direct indicators of short term fluctuations in sea level a detailed comparison of change in the inter tidal assemblages of two southern hemisphere sites at comparable latitudes port hacking new south wales south east australia and the laguna imbituba region of southern brazil indicates periods of marked similarities in the timing and nature of changes at 5200 3800 cal years bp and differences after 2400 cal years bp there is sufficient concurrence of cooling phases and falling sea levels to strongly suggest that in some cases global rather than regional forcing factors are at work the value of inter tidal organisms as indicators of changed environments is developed by identifying the past and present distributions of the common marker species tubeworms barnacles and mussels the 18 o content of these extant specimens at port hacking confirmed changes in ocean water temperature and associated sea level behaviour corresponding to invasion or extinction of temperature sensitive species a similar pattern is repeated although in a less marked fashion in the laguna imbituba region of southern brazil

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

variation of coastal dynamics during the last 7000 years recorded in beach ridge plains associated with river mouths example from the central brazilian coast abstract the reconstruction of relative sea level changes during the last 7000 years has shown that the central brazilian coast was been subjected to submergence until approximately 5100 yr b p however the emergence after 5100 yr b p was interrupted by two important fluctuations with an amplitude of approximately 2 3 m and a duration of 200 300 yr this evolutionary history which is quite different from that of several other regions in the world played an essential role in the development of the central brazilian coastal plains whether or not they are associated with important river mouths the periods of submergence characterized by erosional phases introduced noticeable changes in the geometry of the coastal deposits the periods of emergence gave rise to sandy terraces covered by beach ridges whose orientation is determined by the longshore drift elsewhere on a low sandy coast the direction of longshore sand transport depends on the orientation of the swell in a coast subjected to various swell patterns the efficient swells are defined as those which determine the resulting longshore transport direction such swells are not necessarily the most prevalent for instance along the central brazilian coast the southern sector waves in spite of their infrequent occurrences are much more powerful than the northern sector waves and therefore generate a longshore sand transport from south to north when fossil beach ridges are present as is the case on the central brazilian coast their geometry reflects the past directions of longshore sand transport this makes it possible to determine the provenance of past efficient swells and to establish the past wind patterns a detailed study of the beach ridge geometry of some sections of the central brazilian coast showed a sequence of reversals of the longshore drift during the last 5100 yr with a duration ranging from 10 to 100 yr these reversals represent changes in the direction of effective waves which determine the longshore transportation of sediments and consequently indicate changes in the wind pattern

holocene benthic foraminifera from bahia blanca estuary a review and update of systematic and palaeoenvironmental aspects assemblages of benthic foraminifera in a holocene core from the outer area of bahia blanca estuary in argentina were studied the systematic of the group was updated and provided 28 genera distributed among 59 species six species with nomenclature aperta the main species recorded were buccella peruviana f campsi boltovskoy ammonia beccarii linne elphidium gunteri cole elphidium galvestonense kornfeld elphidium articulatum d orbigny and elphidium discoidale d orbigny these species allowed an estuarine environment to be determined qualitative and quantitative studies conducted on the faunistic content in the core allowed identification of three subenvironments closely linked to sea level fluctuations during the mid holocene a lower zone 6350 yr bp corresponding to a high intertidal environment an intermediate zone 2460 yr bp representing a low intertidal environment related to a system of channels and variations in environmental energy and an upper zone characterized by the developmen

astronomic timescale for the pliocene atlantic δ18o and dust flux records of ocean drilling program site 659 high resolution benthic oxygen isotope and dust flux records from ocean drilling program site 659 have been analyzed to extend the astronomically calibrated isotope timescale for the atlantic from 2 85 ma back to 5 ma spectral analysis of the 18o record indicates that the 41 kyr period of earth s orbital obliquity dominates the pliocene record this is shown to be true regardless of fundamental changes in the earth s climate during the pliocene however the cycles of sahelian aridity fluctuations indicate a shift in spectral character near 3 ma from the early pliocene to 3 ma the periodicities were dominantly precessional 19 and 23 kyr and remained strong until 1 5 ma subsequent to 3 ma the variance at the obliquity period 41 kyr increased the timescale tuned to precession suggests that the pliocene was longer than previously estimated by more than 0 5 m y

cambrian ordovician orogenesis in himalayan equatorial gondwana an early paleozoic tectonic event the kurgiakh orogeny has long been known from the western tethyan himalaya and it is conspicuously recorded by an angular unconformity between cambrian marine shelf deposits and coarse ordovician conglomerate as well as widespread granitic plutons although the lateral extent of this event is poorly known two regions in the central and eastern himalaya the kumaon of india and klippen of bhutan contain conglomerate units that may be correlative with this event in the kumaon the ralam formation which contains a basal polymictic conglomerate unit with detrital zircon grains as young as ca 512 ma is overlain by sandstone containing the arthropod walking trace diplichnites gouldi an ichnospecies known from ordovician and younger strata the late early cambrian trilobite redlichia sp recovered from the underlying martoli group indicates that the conglomerate is post early cambrian and based on stratigraphic analysis also likely records the kurgiakh orogeny in central bhutan the lower paleozoic succession contains conglomerate units with monomictic quartz sandstone clasts and less mature sandstone matrix these units have also been assigned to a variety of ages but rocks that apparently underlie these strata contain the furongian late cambrian zonal trilobite kaolishania granulosa here we show that detrital zircon ages of a conglomerate clast no grains younger than ca 781 ma are distinctly older than those of the matrix which contains a large peak at 490 500 ma thus these conglomerate units are also potential lateral correlatives of the ordovician conglomerate deposits of the western himalaya our paleontological and geochronologic data suggest that the kumaon and bhutan conglomerate units and possible equivalents in tibet correlate with those of the western himalaya this increases their known along strike extent by over 1000 km bringing the total extent to 1200 km thus the kurgiakh orogeny spanned much of the himalayan orogen along the northern gondwanan margin and reflected a widespread tectonic reorganization of the peri gondwanan realm to andean type margins recent work indicates that it also likely extended into the lhasa block and both the north and south china blocks this event was associated with widespread ca 500 ma arc related plutonism recorded in the himalaya and with abundant detrital zircon grains of that age in younger himalaya strata based on current fossil data the duration of the hiatus associated with the cambrian ordovician boundary which separates pre and postdeformational strata ranges from 22 to 36 m y available geochronological data do not provide greater constraint if the event was close in age to the depositional age of the ordovician molasse then the main phase of tectonic uplift erosion and deposition may have been much later than the presumed cambrian ordovician boundary interval age of ca 485 ma

mechanics of basin inversion finite element modelling of the pannonian basin system abstract this finite element modelling study addresses the contraction of rheologically layered and laterally heterogeneous lithosphere representative for the pannonian basin and its surroundings the time interval and strain rate adopted in the experiments reflect the pliocene quaternary inversion of the basin several sets of fully coupled elastoviscoplastic thermo mechanical plane strain 2d models explore the evolution of buckling and stress strain changes across the lithosphere the viscous rheology of the asthenosphere allows for a detailed simulation of isostatic rebound during deformation the numerical models predict the successive development of surface undulations caused by crustal and or lithosphere folding at three different characteristic wavelengths among these the longest wavelength folds occur systematically at the rim of the basin as marginal bulges while the short wavelength folds overprint the earlier folds and are observed at a later stage during compression the thermo mechanical evolution of the lithosphere in response to progressive horizontal contraction is described in terms of a characteristic delay of the changes in the stress regime and a reduction of elastic strain in the strong crustal layers the models predict a change in stress state along the flanks of the basin caused by the development of weak basin lithosphere in their vicinity comparing the modelling results with tectonic features of the pannonian basin has resulted in the identification of three different stages in the pliocene quaternary basin inversion of the pannonian carpathian system

a palaeomagnetic reconnaissance of kashmir northwestern himalaya india abstract thermal demagnetization studies of 800 palaeozoic and lower mesozoic samples mainly carbonates from 14 localities in kashmir showed four magnetic components a a recent field component of normal polarity and large intensity b a middle to late tertiary secondary component of large intensity and of reversed and normal polarity which indicates clockwise rotation of central and eastern kashmir over approximately 45 with respect to peninsular indo pakistan c primary magnetic components of triassic late permian early carboniferous siluro ordovician and middle to early ordovician age the triassic and late permian components show a 20 30 cumulative counterclockwise offset with respect to the indo pakistan apparent polar wander path apwp this indicates a post middle to late triassic counterclockwise rotational movement of kashmir over 65 75 with respect to peninsular indo pakistan d a component of low inclination and predominantly east west declination which is observed only in rocks of pre panjal traps age a secondary origin associated with extrusion of the panjal traps flows is surmised but could not be established beyond doubt alternatively this component may be related to the regional foliation the triassic and late permian primary component directions are predominantly of normal polarity this suggests a pre punjabian late permian upper age limit for the permo carboniferous kiaman reversed polarity interval which is earlier than the early to late tatarian limit observed in the u s s r

low to high amplitude oscillations and secular variation in a 1 2 km late miocene inclination record abstract a miocene section of 2 km thickness was continuously cored near szombathely nw hungary a detailed magnetostratigraphic study has been integrated with results of lithologic sedimentologic and paleontologic studies progressive alternating field a f and thermal demagnetization and rock magnetic and mineralogic studies indicate that the natural remanent magnetization nrm resides in magnetite and the strata contain only minor secondary magnetizations major polarity zones have been defined by inclinations and correlated with the geomagnetic polarity time scale for the interval 10 9 ma inclinations for samples collected at 1 2 m intervals display fine scale oscillations representing secular variation with period times of 400 700 years fluctuating amplitudes of oscillation range from low less than 10 peak to peak to high more than 40 reflecting apparently varying stabilities of the geomagnetic field additionally amplitudes of oscillation progress from low to high and return to low forming oscillation cycles with a periodicity of 6 2 1 8 kyr the oscillations and boundaries of oscillation cycles are generally unrelated to lithology and stratigraphy many oscillation cycles appear to be incomplete and interrupted by high level oscillations some incomplete cycles appear to arise from brief interruptions to the depositional record whereas other interruptions may irregularly arise from a separate component of the geomagnetic field

ichnofossils and their significance in the cambrian successions of the parahio valley in the spiti basin tethys himalaya india abstract the spiti basin exposes well preserved cambrian successions in the tethys himalaya the present ichnofossil assemblage is reported from the debsakhad member of the kunzum la formation the ichnofossils includes the ichnogenera bergaueria chondrites cruziana didymaulichnus dimorphichnus diplichnites helminthorhaphe merostomichnites monocraterion monomorphichnus nereites palaeopascichnus palaeophycus phycodes planolites rusophycus skolithos scolicia treptichnus etc along with annelid worm burrow and scratch marks these ichnogenera can be assigned to cubichnial repichnial pascichnial to fodinichnial behaviors the ichnofossils reported from this section provide evidence regarding the developmental patterns during the early phase of life in absence of trilobites the present assemblage of ichnofossils is very significant in assigning the age of the debsakhad member the abundance of ichnofossils in sandstone siltstone and in shale beds indicate that the ichnocenosis is dominated by a high behavioral diversity ranging from the suspension to deposit feeders three lithofacies were observed in this section they show a vertical disposition which further reflects general upward coarsening trend ichnofossils are mostly produced by arthropods along with crustacean polychaetes and polyphyletic vermiforms due to the paucity of body fossil as well as microbiota in the lowermost beds of the debsakhad member the precambrian cambrian boundary could not be demarcated however the presence of treptichnus and phycodes can be considered as a horizon marker for the beginning of lower cambrian in this section

tianzhushania spinosa and other large acanthomorphic acritarchs of ediacaran period from the infrakrol formation lesser himalaya india covering a time span from ediacaran base of blaini pink carbonates to early cambrian base of tal group the krol belt in the lesser himalaya india occurs as a series of synclines from solan himachal pradesh in the north west to nainital uttarakhand in the south east various lithostratigraphic divisions of this belt reveal many palaeobiological entities namely cyanobacteria algae acritarchs small shelly fossils and trace fossils globally large acanthomorphic acritarchs of the ediacaran period are used as significant biostratigraphic tools for global correlation in the krol belt reports of acanthomorphic acritarchs from the infrakrol and krol a formations of the krol group have further supported this notion this paper reports well preserved microfossils including acanthomorphic acritarchs sphaeromorphic acritarchs coccoids namely tianzhushania spinosa t polysiphonia papillomembrana compta schizofusa sp gloeodiniopsis lamellosa sphaerophycus medium and the unnamed forms a b and c from the chert nodules of the infrakrol formation exposed in the nainital syncline of the kumaun lesser himalaya a biostratigraphic correlation based on acanthomorphic acritarchs suggests that the infrakrol formation is coeval to the lower tianzhushania assemblage zone of the doushantuo formation of south china tianzhushania and papillomembrana are significant additions to the previous record of the ediacaran acanthomorphic acritarchs from the lesser himalaya of india and provide an independent evidence for construction of both biozonation scheme and paleogeography

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

cambrian biostratigraphy of the tal group lesser himalaya india and early tsanglangpuan late early cambrian trilobites from the nigali dhar syncline precise biostratigraphic constraints on the age of the tal group are restricted to 1 a basal level correlative with the anabarites trisulcatus protohertzina anabarica assemblage zone of southwest china 2 a level near the boundary of the lower and upper parts of the tal group correlative with the early tsanglangpuan stage drepanuroides zone and 3 an interval low in the upper part of the tal group correlative with later in the tsanglangpuan stage palaeolenus zone these correlations are based on small shelly fossil and trilobite taxa other chronostratigraphic constraints include the marked negative 13 c isotopic excursion coincident with the transition from the krol group to the tal group this excursion is used as a proxy for the precambrian cambrian boundary in several sections worldwide and if applied to the lesser himalaya indicates that the boundary is at or just above the base of the tal group the upper parts of the tal group may be of middle or late cambrian age and might form proximal equivalents of sections in the zanskar spiti region of the tethyan himalaya both faunal content and lithological succession are comparable to southwest china furthering recent arguments for close geographic proximity between the himalaya and the yangtze block during late neoproterozoic and early cambrian time trilobites from the uppermost parts of the sankholi formation from the nigali dhar syncline are described and referred to three taxa one of which drepanopyge gopeni is a new species they are the oldest trilobites yet described from the himalaya

40ar 39ar geochronology of neogene phreatomagmatic volcanism in the western pannonian basin hungary abstract neogene alkaline basaltic volcanic fields in the western pannonian basin hungary including the bakony balaton highland and the little hungarian plain volcanic fields are the erosional remnants of clusters of small volume possibly monogenetic volcanoes moderately to strongly eroded maars tuff rings scoria cones and associated lava flows span an age range of ca 6 myr as previously determined by the k ar method high resolution 40 ar 39 ar plateau ages on 18 samples have been obtained to determine the age range for the western pannonian basin neogene intracontinental volcanic province the new 40 ar 39 ar age determinations confirm the previously obtained k ar ages in the sense that no systematic biases were found between the two data sets however our study also serves to illustrate the inherent advantages of the 40 ar 39 ar technique greater analytical precision and internal tests for reliability of the obtained results provide more stringent constraints on reconstructions of the magmatic evolution of the volcanic field periods of increased activity with multiple eruptions occurred at ca 7 95 ma 4 10 ma 3 80 ma and 3 00 ma these new results more precisely date remnants of lava lakes or flows that define geomorphological marker horizons for which the age is significant for interpreting the erosion history of the landscape the results also demonstrate that during short periods of more intense activity not only were new centers formed but pre existing centers were rejuvenated

the ichnotaxonomy of conostichus and other plug shaped ichnofossils the systematics of the single entrance plug shaped soft substrate trace fossils have long been in need of revision at least 15 ichnogenera comprising 32 ichnospecies have been used but an exa

mid holocene evolution and paleoenvironments of the shoreface offshore transition north eastern argentina new evidence based on benthic microfauna abstract a sedimentary record spanning 5792 5511 cal yr bp and 3188 2854 cal yr bp was recovered at 36 45 43 s 56 37 13 w south west south atlantic the sedimentological features and micropaleontological benthic foraminifera and ostracoda content were analyzed in order to reconstruct paleoenvironmental conditions considerable environmental fluctuations are indicated by all these proxies five different stages were distinguished stage 1 ca 5800 5000 cal yr bp consists of muddy sand with abundant microfossils in this interval species typical for inner marine shelf environments maintained a high abundance stage 2 consists of plastic light greenish grey clays barren of microfossils and probably represents fluvial input from the de la plata river to the shelf contemporaneous of a lowering of sea level stage 3 is composed of brownish yellow sandy silts and represents increasing marine conditions in the area as reflected by higher faunal diversity and typical foraminifera of inner shelf environments stage 4 is made of homogeneous mud barren of microfossil which represents a new pulse of fluvial input to the shelf in consequence of a new fall in sea level the final part of the core stage 5 is a coarsening upward sequence grading from greeny brown clayey sandy silts to coarse shelly sands and represents the modern sedimentation in the area this interpretation strengthens the stepped model of late holocene sea level fall between 5511 5792 cal yr bp and 2854 3188 cal yr bp in buenos aires coast and agrees with the relative sea level history previously proposed by some authors from western south atlantic coasts

cambrian stratigraphy and depositional history of the northern indian himalaya spiti valley north central india recent work on himalayan tectonics indicates that prior to the cenozoic collision of india and asia an enigmatic cambrian ordovician event may have strongly infl uenced the regional geology of the himalaya stratigraphic and sedimentological analyses of well preserved cambrian deposits are critical for understanding the nature of this early tectonic event and its infl uence on the later tectonic evolution of the himalaya the parahio formation defi ned herein of the parahio valley spiti region in the tethyan himalaya of india is the best biostratigraphically resolved section of cambrian strata in the entire himalaya this formation consists of 1350 m of dominantly siliciclastic deltaic deposits the formation ranges from uppermost lower cambrian lungwangmiaoan stage to middle middle cambrian hsuchuangian stage representing a time span of 5 10 m y it contains numerous mediumscale shoaling cycles that range from storminfl uenced offshore deposits to thick trough cross bedded fl uvial facies many thin carbonate beds with abundant trilobite fossils directly overlie the fl uvial facies and represent transgressive systems tract deposits the cycles are interpreted to have resulted from delta lobe switching based on a lack of systematic stratigraphic changes in cycle or facies thicknesses this paleoenvironmental reconstruction contradicts previous interpretations of this unit that range from deep sea fl ysch to shallow marine tidalites in addition our paleoenvironmental analysis and paleocurrent data suggest that the uppermost lower to middle cambrian deposits of the lesser and tethyan himalaya are parts of the same ancient northward prograding fl uvial deltaic depositional system of the paleo tethys margin of india an angular unconformity with overlying ordovician conglomeratic rocks has considerable local relief with meter scale scours and a valley fi ll 100 m thick the scours have northeast southwest orientations which parallel both the paleocurrents in the underlying parahio formation as well as published paleocurrent readings from the coarse red beds of the overlying ordovician strata the cambrian ordovician unconformity is of regional extent and our recent biostratigraphic database indicates that the minimum hiatus associated with the unconformity in spiti is 15 m y our sedimentological analysis and associated paleocurrent data from the parahio formation along with additional data from units both above and below the unconformity indicate that published models portraying foreland basin development at this time with southward directed thrusting are problematic an alternate possibility that uplift took place south of the tethyan himalaya is also problematic because no published stratigraphic or structural evidence exists for such an uplift to the south for either the greater or the lesser himalaya lithotectonic zones

pan african magmatism and sedimentation in the nw himalaya correlation of early palaeozoic pan african 500 50 ma granites that intruded the chail salkhala haimanta formations in the lesser himalaya zanskar crystallines and lower taglang la of tso morari crystallines in the northwestern himalaya is based on the field relationship tectonic setting mineralogical and geochemical characteristics and isotope dating of the granites these granite plutons exhibit identical petrographical and geochemical character the mineralogical composition of the granites is quite similar consisting of quartz k feldspar plagioclase feldspar biotite muscovite garnet tourmaline cordierite andalusite and sillimanite fibrolite the granite which are massive and inequigranular in the core of the plutons show strongly foliated character indicating development of ductile shear zone at the margins these are peraluminous s type granites having high a cnk value 1 presence of normative corundum rounded shape of zircon and high initial sr ratio suggest crustal source of the granites mantle normalized spider diagram exhibits similar characters for all these granitoids the intrusion of the pan african granites mark an abrupt end of the sedimentation that continued virtually uninterrupted from palaeoproterozoic the sudden break in sedimentation towards the terminal phases of the lower cambrian has been observed in almost all parts in lesser as well as the tethys himalaya occurrences of large number of plutons along different tectonic belts of northwestern himalaya are indicative of widespread tectono thermal event during early palaeozoic 500 50 ma the bracketing of the two features like the break in sedimentation during post late cambrian and the intrusion of granites around 500 50 ma is considered to be the result of a strong diastrophic orogenic event correlatable to the late phases of the pan african orogeny in africa

age and implications of the phosphatic birmania formation rajasthan india abstract the birmania inlier in western rajasthan india contains important phosphate deposits the depositional age of which is poorly constrained here we provide the first direct age constraints for the phosphate bearing birmania formation using a combination of paleontological and detrital zircon u pb data the occurrence of the multicellular algal fossil wengania exquisita in phosphatic chert of the birmania formation suggest that it was deposited during the ediacaran detrital zircon age distributions contain prominent populations of 1 7 1 9 ga grains with subordinate younger grains that range from 650 to 980 ma the distribution broadly resembles those from neoproterozoic strata from both cratonic and himalayan india but like zircon age distributions from the marwar group lacks 1 0 1 2 ga grains which may suggest that both areas shared similar local sources the lack of zircon grains younger than 650 ma is consistent with an ediacaran depositional age because almost all cambrian or younger strata from india have yielded cambrian or latest neoproterozoic age grains these findings raise the possibility of a previously unrecognized late neoproterozoic episode of phosphogenesis on the india craton the presence of wengania exquisita further supports strong palaeogeographic affinity between the india and south china during the neoproterozoic and cambrian

late quaternary productivity changes in the equatorial indian ocean odp hole 716a abstract the equatorial indian ocean is swept by the indian ocean equatorial westerlies iew which intensify in monsoon transitions during april may and october november driving eastward equatorial current eec to the upper ocean the eec brings significant changes in the surface productivity in the equatorial region influencing the life style of the surface and deep sea fauna this study is aimed at understanding 300 kyr record 450 150 kyrs ago of productivity changes linked to variations in iew eec in the equatorial indian ocean using high resolution microfaunal record from integrated ocean drilling program iodp hole 716a maldives ridge in total 451 core samples of 10 cm 3 volume from the 300 kyr long sequence ranging 450 150 kyrs ago were analyzed at every 1 cm interval to generate census data of the benthic foraminiferal fauna factor and cluster analyses using percentages of 53 highest ranked benthic foraminiferal species were run that enabled us to identify five biofacies indicating the varied nature of deep sea environments during the late quaternary the results show a major shift roughly 300 kyr ago across marine isotope stages 9 and 8 mis 9 8 recorded in this study as mid brunhes transition at hole 716a the present study also combines published planktic foraminiferal fauna and pteropod records from hole 716a to understand if the surface to shallow and intermediate water paleoenvironments were coupled with deep water changes during the late quaternary in the maldivian archipelago biofacies robulus nicobarensis trifarina reussi rn tr uvigerina porrecta reussella simplex upo rs and cymbaloporetta squammosa bolivinita sp cs bsp dominate before the mid brunhes transition and document high organic flux with relatively low oxygen paleoenvironment similar to the planktic foraminifer globigerina bulloides population while benthic foraminiferal biofacies hoeglundina elegans miliolinella subrotunda he ms and uvigerina peregrina quinqueloculina seminulum upe qs record high seasonality in food supply with well oxygenated deep water following the mid brunhes climatic transition 300 kyr ago at hole 716a these changes are also recorded in the population of planktic foraminiferal species globigerinoides ruber and neogloboquadrina dutertrei as well as pteropods organic carbon flux linked to changes in the iew eec strength appears to be the most plausible factor controlling faunal assemblages and hence paleoproductivity dynamics in the maldivian region our results suggest that the strength of the iew is inversely related with the indian ocean dipole iod the iod strengthened across mis 9 8 during which time the iew weakened leading to major changes at hole 716a

timing and magnitude of holocene sea level changes along the middle and south patagonian atlantic coast derived from beach ridge systems littoral terraces and valley mouth terraces abstract geomorphologic and chronostratigraphic investigations in various coastal localities along the middle and south patagonian atlantic coast from bahia vera 44 s in the north to san julian 49 s in the south confirm a rich sequence of holocene beach ridge systems and littoral and valley mouth terraces beach ridges are present up to 10 m above current highest tide level htw and date to the early mid holocene transgression maximum beach ridge deposits represent high energy wave dominated coastal environments whereas valley mouth terraces and littoral terraces elevations of 5 5 6 5 m above htw developed in wave protected coastal environments the surface elevation of these littoral forms suggest that the middle and south patagonian atlantic coast is likely undergoing a slow glacio isostatic uplift on the order of 0 3 0 4 mm a since the mid holocene the early holocene sea level rise reached the modern coastline by 8100 14 c years ago c 8600 cal bp at the latest sea level at that time was most likely near its present position the holocene transgression maximum lasted from 6900 to at least 6200 14 c bp c 7400 to 6600 cal bp raising relative sea level to about 2 m to a maximum of 3 m above the present level after which sea level declined to the present level two significant sea level falls of at most 1 m occurred a between 6200 and 6000 14 c bp c 6600 to 6400 cal bp and b between 2600 and 2400 14 c bp c 2300 to 2050 cal bp we assume that both significant sea level falls were predominantly driven by eustatic changes of ocean volume whereas both thermo steric changes and changes of tides may also have contributed to these relatively strong sea level drops gravitational changes driven by greenland ice growth sensu mitrovica et al 2001 may also have amplified any eustatic portion of sea level fall the trend of a general sea level decline since the mid holocene transgression maximum seems to be predominantly glacio isostatically driven

late mid holocene sea level oscillation a possible cause abstract sea level oscillated between 5500 and 3500 years ago at murrells inlet south carolina chezzetcook and baie verte nova scotia and montmagny quebec the oscillation is well constrained by foraminiferal marsh zonations in three locations and by diatoms in the fourth one the implications are 1 there was a eustatic sea level oscillation of about 2 10 m in the late mid holocene on the southeast coast of north america south carolina to quebec that is not predicted by present geophysical models of relative sea level change 2 this oscillation coincides with oceanographic cooling on the east coast of canada that we associate with melting ice and 3 this sea level oscillation climatic event coincides exactly with the end of pyramid building in egypt which is suggested to have resulted from a climate change i e drought cooling this sea level climatic change is a prime example of feedback where climatic warming in the mid holocene promoted ice melt in the arctic which subsequently caused climatic cooling by opening up arctic channels releasing cold water into the inner labrador current that continued to intensify until 4000 years ago this sea level event may also be the best way of measuring when the final ice melted since most estimates of the ages of the last melting are based on end moraine dates in the arctic which may not coincide with when the last ice actually melted out since there is no way of dating the final ice positions

a review of indian phanerozoic palaeomagnetism implications for the india asia collision abstract an overview is presented of the indian apparent polar wander path apwp for the phanerozoic and in particular for post late palaeozoic times this apwp is compiled on basis of data available at october 1981 from peninsular and extrapeninsular indo pakistan and from dsdp cores from the indian plate one of the more important and newly recognized features of this apwp is a large scale triassic jurassic loop this loop indicates a changeover from a late palaeozoic early mesozoic northwards and counter clockwise rotational movement with greater india reaching moderately low southern latitudes into a southwards and clockwise rotational movement during the early to middle jurassic recognizable likewise in apwp s from other gondwana continents this loop reflects the opening of the neotethys studies of extrapeninsular regions up to and north of the indus tsangpo suture zone have shown wide spread presence of magnetic overprints which delineate two regionally confined age groups younger overprints 20 40 m y predominate in the more external thrust zones older overprints 50 60 m y in contrast are found in the more internal zones both north and south of the indus tsangpo suture zone the latter are interpreted to reflect a late phase of relaxation in the early tertiary collision of greater india with south central asia or off shore island arcs which occurred at equatorial to low northern palaeolatitudes 0 10 n subsequent northwards movement over 2500 3000 km or more and impingement of greater india into southern asia resulted into large scale underthrusting of greater india along the main central thrust beneath southern tibet and to clockwise rotation of thrust units in the western himalaya a discrepancy between indian palaeomagnetic data and results available todate from southern tibet is discussed

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

proterozoic sedimentation and pan african geodynamic development in the himalaya abstract the purana or proterozoic lower cambrian continental margin sedimentary succession of the lesser himalaya comprises three lithological divisions a lower argillo arenaceous group a middle carbonate succession and an upper argillo calcareous assemblage the poorly sorted basal sediments consisting of wacke slate alternations of the lower group were emplaced by currents including turbidity currents which in the early stage flowed northwards from the aravalli and satpura mountains of peninsular india lenticular deposits of diamictite within the flysch succession represent submarine slides penecontemporaneous basaltic lavas and associated tuffs interbedded with shallow water arenites making up the bulk of the upper part of the lower group were related to rifting of the basins the overlying dolomites and dolomitic limestones were laid down on a very shallow stable shelf and are characterised by columnar branching stromatolites and lenticular units of crystalline magnesite and associated talc lenticular diamictites towards the top of the upper group of slates and limestone are harbingers of tectonic movements culminating towards the end of the early cambrian in an upheaval which abruptly terminated sedimentation throughout the lesser himalaya and peninsular india and caused a pronounced interruption of sedimentation in the tethyan domain in the northern himalaya the cambro ordovician 500 25 ma granites intruding the lesser himalayan thrust sheets of lower proterozoic metamorphic rocks and the upwarped northern front of the himalaya signify an important tectonic event that terminated the purana proterozoic lower cambrian sedimentation in the indian subcontinent this seems to be related to the tectonic movements that occurred towards the close of the late proterozoic or early cambrian

birth life and death of the pannonian lake abstract the miocene pliocene pannonian lake formed in an extensional basin system behind the compressional arc of the carpathians its size and depth were comparable to those of the caspian sea subsidence began in middle miocene times forming deep pelagic basins separated by reef bearing ridges clastic influx filled the marginal basins during middle miocene time prograding deltas dissected the lake and completed the infilling of the basin system by the end of the pliocene basin plain prodelta delta front delta plain beach fluviatile and marsh environments can be recognized terminal miocene uplift of the carpathians isolated the pannonian region from the rest of paratethys the subsequent decrease of salinity resulted in the evolution of an endemic freshwater mollusc fauna rich nutrient influx from rivers supported high organic productivity dinoflagellates diatoms nannoplankton foraminifers ostracods etc yielding organic rich sediments preservation of organic matter was helped by a stratified water column and oxygen deficient bottom conditions deep burial continuing subsidence and high geothermal flux due to an extremely thin crust led to the formation of commercially exploitable oil and gas accumulations shallow lacustrine zones of basin margins provided suitable environments for a rich congeria melanopsis mollusc fauna wave action on beaches produced commercially exploitable pure quartz sand deposits taxodium and alnus forests flourished around the lake producing enormous lignite deposits besides a rich land snail and mammal fauna prehominids lived in the forests there was a warm temperate climate with probably frostfree winters basaltic volcanoes overlooked the landscape and maars hosted minor lakes with rich algal flora forming oil shale the catchment area included most of the carpathians and parts of the apls and dinarides the positive water balance resulted in a supposed overflow in the southern margin supplying exotic fauna to the south carpathian and dacian basins of the eastern paratethys the pannonian lake was completely filled by the end of pliocene recent lakes in the carpathian basin are not descendants of it

cambrian trace fossils of the cruziana ichnofacies from the bikaner nagaur basin north western indian craton abstract the marwar supergroup of the bikaner nagaur basin is composed of sediments deposited from the late neoproterozoic ediacaran to upper cambrian the nagaur sandstone formation of the nagaur group uppermost division of the marwar supergroup preserves trace fossils significant for establishing early cambrian biostratigraphic zones and depositional facies fifteen ichnospecies and eight ichnogenera identified in the nagaur sandstone formation include treptichnus pedum cruziana cf tenella cruziana isp diplichnites ispp a b and c gyrophyllites isp lockeia isp merostomichnites isp monomorphichnus gregarius isp nov monomorphichnus isp planolites isp psammichnites isp rusophycus bikanerus isp nov rusophycus cf carbonarius rusophycus isp and radial trace fossils these trace fossils belong to ethological categories pascichnia repichnia cubichnia and fodinichnia and represent arthropod and worm like burrowing biota the assemblage and a regional comparison with contemporaneous trace fossils in the eastern gondwanan realm suggest that the sequence in the study area belongs to the cruziana tenella ichnozone and to stage 2 upper part of terreneuvian however the middle cambrian is not excluded the trace fossil assemblage belongs to the archetypal cruziana ichnofacies cross bedded sandstone mud cracks and rainprints in the ichniferous strata of the nagaur sandstone formation indicate deposition in an intertidal sand flat with channels that was exposed episodically

modelling holocene relative sea level observations from the caribbean and south america abstract holocene data from the caribbean and the atlantic coast of south america have been critically assessed and a subset of the best quality data are presented these data cover a large north south geographic extent and display a distinct spatial variation we make the first comparisons of this data set to predictions based on a realistic model of glaciation induced sea level change with the main aims of understanding the cause of the observed spatial trend and estimating a eustatic signal for the holocene the spatial variation is dominated by the influence of the ice and ocean mass redistribution on sea level change with the ice induced effect dominating the observed north south trend a best fitting model is applied to estimate a holocene eustatic signal from the observations we find that the model corrected data are consistent with a relatively rapid rise of 7 8 mm yr in the early holocene with a marked reduction in this rate around 7 cal kyr bp from this time until present the model corrected data suggest that the volume of mass transfer between ice sheets and oceans was no more than 1 m eustatic sea level equivalent

holocene climate variability although the dramatic climate disruptions of the last glacial period have received considerable attention relatively little has been directed toward climate variability in the holocene 11 500 cal yr b p to the present examination of similar to50 globally distributed paleoclimate records reveals as many as six periods of significant rapid climate change during the time periods 9000 8000 6000 5000 4200 3800 3500 2500 1200 1000 and 600 150 cal yr b p most of the climate change events in these globally distributed records are characterized by polar cooling tropical aridity and major atmospheric circulation changes although in the most recent interval 600 150 cal yr b p polar cooling was accompanied by increased moisture in some parts of the tropics several intervals coincide with major disruptions of civilization illustrating the human significance of holocene climate variability c 2004 university of washington all rights reserved

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

an assessment of the age and tectonic setting of volcanics near the base of the windermere supergroup in northeastern washington implications for latest proterozoic earliest cambrian continental separation mafic metavolcanics of the huckleberry formation in northeastern washington occur near the base of the windermere supergroup a sequence of immature clastic rocks thought to have been deposited dur

stratigraphy and sedimentary history of the nepal tethys himalaya passive margin abstract the sedimentary history of the nepal tethys himalaya began with deposition of thick carbonates in the cambro ordovician followed by a mixed siliciclastic carbonate epicontinental succession recording two major deepening events in the early silurian and late devonian fossiliferous carbonate ramp deposits in the tournaisian were disconformably followed by white quartzose sandstones and black mudrocks with locally intercalated diamictites derived from sedimentary rocks and deposited in asymmetric tectonic basins rift stage break up in the mid early permian locally associated with effusion of tholeiitic lava flows was followed by a transgressive sandy to shaly locally coal bearing or bioclastic unit capped by condensed pelagic carbonates in the middle to late permian juvenile ocean stage subsidence of the cooling stretched crust led close to bathyal water depths in the olenekian but then slowed down in the middle triassic to increase again sharply in the late triassic owing to renewed extensional tectonic activity and sediment loading during up and out building of the indian continental terrace deposition of tropical platform carbonates finally became widespread in the middle liassic mature passive margin stage the initial fragmentation of gondwana in the middle jurassic led to rejuvenation of the indian craton and deposition of quartzo feldspathic hybrid arenites capped by condensed oolitic ironstones deposited at warm subtropical latitudes in the late bathonian middle callovian next a discontinuous pelagic grey marly limestone unit was followed by the ammonoid rich offshore spiti shale in the late jurassic the final disintegration of gondwana began in the berriasian when quartzose siliciclastics derived again from the rejuvenated indian craton and partly from recycling of older clastic successions were followed by thick deltaic to shelf volcaniclastics documenting eruption of alkali basalts in the valanginian followed in the hauterivian to albian by more felsic differentiates such as the trachyandesites exposed in the lesser himalaya 120 km to the south a widespread drowning episode fostered by waning volcaniclastic supply during a global eustatic rise is documented by a major glauconitic horizon deposited at middle southern latitudes in the late albian overlain by scaglia like pelagic limestones in the latest albian the final part of sedimentary history during the rapid northward flight of india and its collision with eurasia is not documented anywhere in nepal due to later erosion of upper cretaceous to lower tertiary strata

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

the precambrian cambrian boundary problem and its prospects northwest himalaya india the precambrian cambrian boundary problem is studied in an areno argillaceous sequence in the kashmir and spiti valley northwest himalaya india in kashmir a rich and diversified microbiota cryptarchs and algae of the late precambrian and low lower cambrian trace fossils are recorded in the spiti valley the yield of microbiota is poor and the trace fossils are late lower cambrian modified journal abstract

the muddy bottom of lake pannon a challenge for dreissenid settlement late miocene bivalvia abstract the late miocene dreissenids of lake pannon a long existing eastern central european lake bear witness to two very different modes of life which allowed these bivalves to successfully settle in what appears to be an inhospitable environment one guild is restricted to the genera mytilopsis conrad 1858 and sinucongeria lorenthey 1894 these representatives are extreme r strategists which tend to produce temporal boom and bust populations during time windows of improved ecological conditions these opportunities are interpreted here to correlate with cyclic shifts in the epilimnion hypolimnion relation and the corresponding oxygenation of bottom waters events which are probably triggered by low frequency orbital forcing the second guild is composed solely of congeria partsch 1836 the paradox of the proliferation of a single species characterised by extreme size and weight in a muddy oxygen deficient lake environment avoided by nearly all other molluscs points to a hidden mechanism not accessible to other species we tentatively link this mechanism with chemosymbiosis functional morphology in interplay with a highly sulphidic over saturated interstitial water support an interpretation of the large congeria subglobosa as a successful h2s pump model

the himalayan passive margin from precambrian to cretaceous times abstract the himalaya passive margin should be separated into the indian himalaya and the pakistan himalaya divided by the nanga parbat haramosh basement uplift in the northwestern syntaxes the indian passive margin shows a complex history involving splitting of microcontinents off the northern gondwana margin from early paleozoic times until the jurassic in contrast the pakistan himalaya formed part of the stable indian shelf until separation from africa started in the jurassic each margin has a distinct stratigraphic history until the mid mesozoic after which they show similar histories until the tertiary the himalaya mountains in india consist of three distinct tectonic units juxtaposed during the neogene by southward thrusting of the northern indian precambrian to mesozoic passive margin the lesser himalaya on the south forms a late precambrian passive margin usually directly overlain by late cretaceous to tertiary clastics its stratigraphy is closest to that of the indian shield in contrast the high himalaya has a thin ordovician to carboniferous shelf sequence deposited after early ordovician deformation and granite intrusion above this thick permian and mesozoic shelf sequences mark the separation of continental blocks off the northern indian margin and the opening of the neotethys ocean the north himalaya formed the slope and basin of this ocean and consists of reactivated paleozoic gneiss domes overlain by thick mesozoic sediments which pass in the northeastern himalaya into an enormously thick sedimentary sequence resting on oceanic crust paleomagnetic and structural evidence indicates at least 500 km of southward thrusting along the main central thrust between the lesser and high himalaya this thrusting together with a further 250 km of erosion at the front of the nappes has removed the entire inner shelf of the himalaya passive margin and can explain the startling contrast between the high and lesser himalaya stratigraphic sequences but there are still discrepancies particularly in the eastern himalaya where precambrian basement is juxtaposed with the north himalaya mesozoic slope these discrepancies can be partly resolved by strike slip movements roughly parallel to the himalaya which have removed parts of the northern indian passive margin such faults of the requisite orientation displacement and age occur in southeast asia where their cumulative displacements can add up to several thousand kilometres similar faults of undoubted pre tertiary age occur in the pakistan himalaya here the passive margin shows a much simpler history of jurassic to miocene subsidence

changes in the trace fossil biota across the proterozoic phanerozoic boundary trace fossils became relatively diverse in shallow water clastic seas in the late proterozoic vendian with a further significant increase in abundance diversity and complexity in the tommotian and atdabanian little change followed in the remainder of the lower palaeozoic traces typical of deeper water facies evolved in shallow water during the vendian and early cambrian and may have slowly migrated into the deep ocean during the remainder of the lower palaeozoic there are a limited number of short ranging ichnogenera which may be useful for correlation but the first appearance of ichnogenera may be a more satisfactory method three trace fossil zones covering the ranges redkino and kotlin rovno and tommotian lower atdabanian are recognized and may be useful for world wide correlation

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

centennial to decadal scale environmental shifts in and around lake pannon vienna basin related to a major late miocene lake level rise a detailed ultra high resolution analysis of a 37 cm long core of upper miocene lake sediments of the long lived lake pannon has been performed despite a general stable climate at c 11 9 ma several high frequency oscillations of the paleoenvironments and depositional environments are revealed by the analysis over a short time span of less than 1000 years shifts of the lake level associated with one major 3rd order flooding are reflected by all organisms by a cascade of environmental changes on a decadal scale within a few decades the pollen record documents shifting vegetation zones due to the landward migration of the coast the dinoflagellate assemblages switch towards offshore type due to the increasing distance to the shore the benthos is affected by low oxygen conditions due to the deepening this general trend is interrupted by smaller scale cycles which lack this tight interconnection especially the pollen data document a clear cyclicity that is expressed by iterative low pollen concentration events these negative cycles are partly reflected by dinoflagellate blooms suggesting a common trigger mechanism and a connection between terrestrial environments and surface waters of lake pannon the benthic fauna of the core however does not reflect these surface water cycles this forcing mechanism is not understood yet but periodic climatic fluctuations are favoured as hypothesis instead of further lake level changes short phases of low precipitation reducing pollen production and suppressing effective transport by local streams might be a plausible mechanism this study is the first hint towards solar activity related high frequency climate changes during the vallesian late miocene around lake pannon and should encourage further ultra high resolution analyses in the area

tectonic versus climatic control on the evolution of fluvio deltaic systems in a lake basin eastern pannonian basin abstract the pannonian basin is a back arc lake basin situated inside the central european carpathian loop surrounded by the orogenic belts of the eastern alps carpathians and dinarides integrated stratigraphical and sedimentological research reported here focuses on palaeogeographical evolution and particularly the response of the fluvio deltaic systems to climatic and tectonic controls in the late neogene sedimentary succession in the eastern part of the pannonian basin this work has been carried out using subsurface data including regional composite seismic profiles and well logs dip sections were studied to define the stratigraphical architecture depositional environments and sequence stratigraphy and to interpret the sedimentary evolution of the area the eastern pannonian basin is characterized by sediment input from the north east which was one of the main routes of the fluvial deltaic systems entering and progressively filling lake pannon from 11 6 2 6 ma the formations studied were deposited in environments that ranged from the deep water basin plain slope delta front and coastal plain to alluvial plain causing the deposition of characteristic lithofacies associations and characteristic biofacies these form laterally continuous lithofacies units that can be correlated through the basin all depositional facies units have considerable thicknesses 300 1000 m in the deepest parts of the sub basins sequence stratigraphical interpretation was carried out correlating 3rd and 4th order sequences ma to ky in range through a regional composite seismic profile network in the dip direction stratigraphical architecture and sedimentary facies indicate that the 3rd order cycles were controlled by tectonic driving forces while 4th order cycles were probably driven by large scale climatic changes within the milankovitch band in the 3rd order time interval pa 3 between 9 1 and 6 8 ma a major tectonostratigraphic event occurred highlighting the role of strike slip faulting related transtensional subsidence in the derecske sub basin superimposed on the regional post rift thermal subsidence of the eastern pannonian region the substantial base level fall at sb pa 4 at 6 8 ma over 200 m perhaps amplified by subsequent tectonic movements can be related to the onset of a new compressional phase of structural evolution in the basin

relative sea level changes in the last 5500 years in southern brazil laguna imbituba region santa catarina state based on vermetid ages abstract twenty six new radiocarbon dates from vermetid shells collected in the southernmost sector of the brazilian rocky coast presented dates ranging from 5410 80 to 190 65 years b p with associated paleosea levels varying from 2 10 m to 0 20 m above present sea level the overall suggested trend of the relative sea level rsl declining until at least 190 years b p is somewhat contradictory to a proposed rsl rise in the last 1000 years in southern brazil the data also seem to undermine a more widely accepted rsl trend that suggests that at least two negative rsl oscillations occurred between 4100 and 3800 years b p and between 3000 and 2700 years b p the maximum elevation of the rsl in the holocene in southern brazil was possibly lower than that observed in most of the brazilian eastern coast discrepancies between ancient sea levels of similar ages are attributed to coincidental methodological problems to imprecisions in determining past relative sea levels and to possible changes in the geomorphology and wave climate close to shore during the last 5000 years a general trend of increasing 18 o with a reduction in age in the studied samples may suggest a gradual reduction of water temperature in the region during the same period

sedimentary evidence of a cambro ordovician orogenic event in the northwestern himalaya abstract the late proterozoic early paleozoic sequence of the tethys himalaya provides evidence of an orogenic episode close to the cambrian ordovician boundary late pan african event pre middle cambrian sediments were deposited on a terrigenous tidal flat gradually passing upward to a peritidal carbonate platform the succession shows an overall transgressive trend which is reproduced at smaller scale by second and third order coarsening upward cycles terminated by the landward shift of carbonate facies during highstands of sea level sandstone petrography suggests a passive continental margin setting for this part of the sequence in middle cambrian times the carbonate platform underwent gradual drowning and outer shelf slope shales with intercalated tuffaceous material erupted from a nearby immature volcanic arc were deposited the shales are overlain by basinal turbidites attesting to the growth of a sandstone lobe enclosed in lobe fringe siltstones in the middle ordovician unconformable alluvial fan conglomerates and braid plain sandstones derived from uplifted sedimentary sequences indicate erosion of a newly formed orogenic belt comparison with early paleozoic and recent counterparts allows to interpret the cambro ordovician sedimentary evolution in terms of foreland basin development the thermal subsidence of a passive margin temporarily reduced by the passage of a peripheral bulge was enhanced strongly by flexural downwarping towards a subduction zone collision of a buoyant continental margin at the trench hampered subduction rapid uplift ensued with formation of a foreland fold thrust belt shedding sedimentary detritus into the adjacent molasse basins

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

the brazilian sea level curves a critical review with emphasis on the curves from the paranaguaand cananeia regions abstract relative sea level curves for the mid to late holocene have been proposed for eight different sectors along the brazilian coast this paper aims to review the data used to construct the curves proposed for two sectors the paranaguaand cananeia regions in southeast brazil more specifically we analyze the palaeo sea level indicators vermetid tubes shells wood fragments and shell midden deposits related to 1 the sea level maximum of the mid holocene and 2 the two secondary oscillations that would have occurred between 4100 3800 years b p and 3000 2700 years b p the sedimentary deposits of the coastal plain as well as vermetid datings suggest a mid holocene sea level maximum between 3 5 and 4 m the great majority of the indicators used to infer the secondary oscillations in previous studies were derived from shell middens besides being unreliable palaeo sea level indicators these data also showed inconsistencies that undermine the existence of such oscillations the plot of all the data derived from vermetid samples found along the brazilian coast also indicate a rather smoother sea level fall in the last 5100 years

skeletal microfauna of meishucunian and qiongzhusian precambrian cambrian boundary age from the ganga valley lesser himalaya india the earliest skeletal microfauna of precambrian cambrian age recovered from the lower tal sequence chert phosphorite to calcareous members of the tal formation exposed in the ganga valley lesser himalaya uttar pradesh india has been grouped into three assemblages in ascending order these are assemblage i containing anabarites trisulcatus missarzhevsky tiksitheca korobovi miss circotheca sp turcutheca sp spirellus columnorus jiang and olivooides alveus qian assemblage ii yielding allonia erromenosa jiang a sp cf a erromenosa jiang dimidia simpleca jiang d sp cf d simpleca jiang and hyolithellus sp and assemblage iii comprising pelagiella lorenzi kobayashi auriculatespira madianensis zhou xiao and a andunca he pei the assemblages i and ii are correlatable to the meishucunian zone i and zone iii respectively and the assemblage iii to the qiongzhusian stage of china thus the lower tal sequence is assigned to precambrian cambrian age

milankovitch scale multi proxy records from fluvial sediments of the last 2 6 ma pannonian basin hungary abstract the continuous cores of two nearly 500 m deep boreholes cutting pleistocene fluvial sequences in the eastern part of the pannonian basin hungary have been studied magnetostratigraphy indicates that the sediment sequences span the last 2 6 ma without significant hiatuses comparison of systematic variations in magnetic susceptibility with changes in grain size distribution revealed milankovitch scale cyclicity in sedimentation of 40 and 100 kyr cyclicity which also shows a correspondence with the 18o variations of the odp 677 site comparison of pollen and gastropod paleoecological data with the magnetic susceptibility proxies suggests that climate was a major allogenic control on the cyclicity zones of high magnetic susceptibility correspond closely with sandy and coarse silty parts of the borehole successions which largely coincide with pollen and molluscs indicating a warm climate on the contrary zones with low magnetic susceptibility correspond to silts and clays and in most cases coincide with cold climate indicator pollen and molluscs heavy mineral and xrd studies revealed that magnetic susceptibility reflects the absolute amount of detrital fe oxide minerals mostly magnetite variations in the amount of magnetite are related to changes in heavy mineral content which arise primarily from changes in sediment supply to the basin by rivers the depositional model for the pleistocene fluvial sediments suggests that sediment flux increased towards the basin during interglacials due to the increased discharge and transport capacity of the rivers while a decreased sediment supply to the distal parts of the basin occurred during glacials a delay between erosion and storage of weathering products near to the source area and subsequent transportation and re deposition of sediments in the basin interior setting is an important cause of this effect

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

post rift compressional reactivation potential of passive margins and extensional basins poly phase deformation of a compressional nature is a common feature in the post rift evolution of passive margins and rifts the compressional mode of deformation in these sedimentary basins originally formed by extension in an intraplate setting is characterized by a spectrum of spatial wavelengths spanning several tens of kilometres up to several hundreds of kilometres the actual mode of compressional deformation appears to be strongly affected by the rheological structure of the underlying lithosphere the level of the regional intraplate stress field and the geometry of the rifted basin configuration prior to late stage compressional reactivation the interplay of plumes and intraplate compressional deformation can lead to temporal transitions from basin inversion to lithospheric folding these modes of deformation lead to substantial differential vertical motions late stage anomalies in subsidence and uplift patterns the development of innovative combinations of numerical and analogue modelling techniques is the key to differentiating different modes of compressional deformation of passive margins and extensional basins the geological society of london 2008