present day kinematics of the mediterranean a comprehensive overview of gps results i combine recently published gps results to derive a geodetic horizontal velocity field consistent at the scale of the mediterranean and the surrounding alpine belts the velocity field is then used to discuss the boundary conditions around each major deforming area in the mediterranean to describe the main patterns of motion and deformation to critically review the existing kinematics models and to finally point out the main unresolved kinematics questions strain rate in europe north of the alpines belt is dominated by the signature of the glacial isostatic adjustment and tectonic strain remains below the current accuracy of gps results in the western mediterranean deformation is restricted to the betics the alboran and the morrocan rif with west to southwestward motion with respect to iberia which is part of stable europe shortening consistent with the relative nubia eurasia plate motion is found throughout the maghrebides but the distribution of deformation in northern africa remains largely unknown the central mediterranean is dominated by the counter clockwise rotation of the adriatic the junction between the southern adriatic domain and nubia has yet to be firmly established the deformation over a wide area east of the maghrebides in tunisia and the gulf of sirte in libya still remains to be quantified in the eastern mediterranean the velocity field is dominated by a general anti clockwise rotation and a general trend towards the hellenic trench with velocity magnitude increasing with decreasing distances from the trench this trend is observed not only in the aegean and anatolia but also in the southern balkans geodetic results emphasize that the convergence of the nubia and arabia plates towards eurasia directly controls the deformation across only very few segments along the plate boundary zone additional processes are therefore required to explain the observed velocity field and deformation pattern

early diageneitc isotopic signal at the cretaceous tertiary boundary israel abstract carbon and oxygen isotope records from carbonate fractions in marls overlying the k t boundary in southern israel are used to interpret paleoenvironmental changes and the history of early diagenetic events in the earliest tertiary the 13c record of the whole rock does not significantly depart from the original values and reflects the global productivity drop shortly after the k t boundary and the subsequent recovery fine fraction oxygen isotope values reflect the addition of carbonate cement highly depleted in 18o throughout the profile the 18o record demonstrates two main episodes in which contact with fresh water affected the sediments one is below a short hiatus at planktic foraminiferal subzone transition po p1a guembelitria cretacea parvularugoglobigerina eugubina and the other at an pyrite rich clay layer near the top to planktic foraminiferal subzone p1b globigerina taurica the latter event suggests introduction of sapropelic bottom conditions in the oceanic paleoenvironment

upheavals during the late maastrichtian volcanism climate and faunal events preceding the end cretaceous mass extinction abstract the late maastrichtian was a time of major climate evolution and extinction extremes rapid climate warming of 2 3 c in intermediate waters between 69 5 and 68 ma top c31r to base c30n accompanied maximum evolutionary diversification 43 increase zone cf5 to low cf4 in planktic foraminiferal history followed immediately by a cluster of extinctions during the last 250 ky of the maastrichtian c29r zones cf2 cf1 rapid warming of 4 c in intermediate waters and 8 c on land resulted in high stress environments ending in the mass extinction the end cretaceous mass extinction is recorded in sediments between massive deccan lava flows in india and attributed to so 2 and co 2 outgassing leading to ocean acidification the early late maastrichtian climate and faunal upheavals are not well known here we document the faunal similarities of both events from the indian ocean through the tethys and gulf of mexico results show that both extreme warm events are marked by high stress environments characterized by decreased abundance and diversity of large specialized species and dwarfing high abundance of low oxygen tolerant species and disaster opportunist surface dweller guembelitria blooms the similarity in faunal response with the deccan warming of c29r cf2 cf1 suggests that volcanism was also responsible for the warming and faunal upheaval of the early late maastrichtian major volcanic activity at this time included the onset of deccan eruptions and ninetyeast ridge volcanism the role of the chicxulub impact appears to have been a contributing rather than causal factor in the mass extinction

the cretaceous tertiary boundary stratotype section at el kef tunisia how catastrophic was the mass extinction abstract the cretaceous tertiary k t boundary stratotype section at el kef tunisia represents the most complete and expanded sedimentary record across this important mass extinction horizon presently known high resolution analysis of planktic foraminifera in two outcrops el kef i stratotype and el kef ii along with comparisons between planktic and benthic foraminifera calcareous nannofossils ostracods pollen and spores and dinoflagellates indicate that major changes across the k t boundary are registered only in benthic and planktic foraminifera and calcareous nannofossils biotic changes in benthic foraminifera are unique to el kef and similarly shallow continental shelf sections and appear to be the result of a sea level regression in the latest maastrichtian followed by a sea level rise across the k t boundary that was accompanied by expansion of the local oxygen minimum zone omz biotic changes in planktic foraminifera appear partly related to these conditions also but in general reflect more global oceanographic changes for instance species extinctions are gradual and selective as observed in k t sections worldwide rather than random and abrupt although there is a 69 decline in species richness between 25 cm below and 10 cm above the k t boundary only rare species disappeared their combined relative abundance constitute less than 20 of the total population about 52 of these extinct taxa 8 of the population are large ornate morphologically complex tropical subtropical forms that lived at or below the thermocline no planktic foraminifera from this depth range survived the k t boundary event all survivor taxa were surface dwellers living within the photic zone their relative abundance 80 dominates both cretaceous and early tertiary populations these data indicate that the k t biotic record in the shallow continental shelf section at el kef was significantly influenced by local conditions which combined with the latest maastrichtian sea level regression and subsequent sea level rise resulted in shallowing of the local omz relative to the sea surface shallowing of the local omz lead to the selective disappearance of benthic faunas and may have adversely affected the surviving photic zone dwellers the selective nature of species extinctions however appear to be related partly to long term global oceanographic changes which were accelerated at the k t boundary possibly by a bolide impact

multiple impacts across the cretaceous tertiary boundary abstract the stratigraphy and age of altered impact glass microtektites microkrystites ejecta layers from the chicxulub crater are documented in late maastrichtian and early danian sediments in mexico guatemala belize and haiti in northeastern mexico two to four ejecta layers are present in zone cf1 which spans the last 300 ky of the maastrichtian the oldest ejecta layer is dated at 65 27 0 03 ma based on sediment accumulation rates and extrapolated magnetostratigraphy all younger ejecta layers from the maastrichtian and early danian parvularugoglobigerina eugubina zone pla l may represent repeated episodes of reworking of the oldest layer at times of sea level changes and tectonic activity the k t boundary impact event 65 0 ma is not well represented in this area due to widespread erosion an early danian pla l ir anomaly is present in five localities bochil actela coxquihui trinitaria and haiti and is tentatively identified as a third impact event at about 64 9 ma a multiimpact scenario is most consistent with the impact ejecta evidence the first impact is associated with major deccan volcanism and likely contributed to the rapid global warming of 3 4 c in intermediate waters between 65 4 and 65 2 ma decrease in primary productivity and onset of terminal decline in planktic foraminiferal populations the k t boundary impact marks a major drop in primary productivity and the extinction of all tropical and subtropical species the early danian impact may have contributed to the delayed recovery in productivity and evolutionary diversity

offset rivers drainage spacing and the record of strike slip faulting the kuh banan fault iran abstract this study concerns the ways in which rivers can record part but not necessarily all of strike slip fault offset the focus is the active right lateral kuh banan fault in eastern iran within the arabia eurasia collision plate convergence has caused thrust and strike slip faulting across sw asia the active slip rate of the kuh banan fault is 1 2 mm yr total displacement is 5 7 km as determined from offset geological markers and the length of a pull apart basin a component of thrusting has generated 1 km of relief which preserves the offset of rivers displaced laterally by the strike slip motion ridge half widths w and river outlet spacings along the fault s are related by the drainage spacing parameter r where r w s published data for older larger mountain ranges have extremely characteristic drainage spacing r 2 1 drainage spacing along the kuh banan fault has a mean value of 1 8 and is much more variable r 1 1 3 1 due to local structural complexities which have influenced river courses most river offsets along the kuh banan fault are small

maturity of central madagascar s landscape low temperature thermochronological constraints abstract low temperature thermochronological data from two profiles across central madagascar give apatite fission track and apatite u th he ages ranging between 258 ma and 176 ma and from 239 ma to 48 ma respectively thermal models derived from these data as well as modelling of basement denudation and the sedimentary record indicate that first order topography of central madagascar developed mainly due to flexural uplift during mesozoic times this was in response to successive erosion and depositional loading associated with the sedimentation in the morondava and majunga basins both of which are now exposed along the western margin of madagascar our data suggest that the eastern margin of the island had a similar denudation history and was probably at a similar topographic level before the late cretaceous break up of madagascar and the india seychelles block cretaceous normal faulting without major amounts of denudation led to the development of the present east coast topography defined by a tectonically juvenile escarpment in the centre of the island cenozoic tectonics and volcanism has had a minor and localised influence on the landscape of central madagascar

paleoenvironmental changes across the cretaceous tertiary boundary at koshak kazakhstan based on planktic foraminifera and clay mineralogy abstract the koshak section of the mangyshlack peninsula kazakhstan is one of the most complete cretaceous tertiary k t transitions known from the boreal paratethys cretaceous species richness is low 11 to 13 species except for a peak of 20 species near the k t boundary in the uppermost maastrichtian top 50 cm that represents the temporary incursion of low latitude taxa this maximum species richness occurred during climatic warming associated with increased humidity as suggested by clay mineral analyses biofacies analysis suggests external platform conditions at this time followed by a more humid climate a sea level transgression and deepening basinal facies in the lower danian subzone p1a shallower platform conditions resumed in danian subzones p1b and p1c accompanied by a cooler and probably more arid climate no abrupt mass extinction occurred at the koshak k t boundary which is marked by an ir anomaly a clay layer and the first appearance of tertiary planktic foraminifera the influx of lower latitude species ends at or before the k t boundary whereas the majority of the indigenous cretaceous assemblage survived into the danian these data suggest that long term climatic changes may have been the principal factors in the progressive demise of the cretaceous planktic foraminifera in the eastern boreal paratethys

40ar 39ar dating of mineral separates and whole rocks from the western ghats lava pile further constraints on duration and age of the deccan traps abstract there has been an ongoing debate for almost two decades on the age and duration of deccan trap volcanism some of the best available ages have been determined using the 40 ar 39 ar method but differences in sample location laboratory procedure type of analyzed material and ages of monitors may have been responsible for much of the apparent spread in the data we have collected and analyzed samples from close to the bottom and top of the main lava pile in the western ghats near bombay we confirm previous findings that alteration and ar recoil strongly affect these rocks particularly measurements made on whole rocks when mineral separates mostly plagioclase are analyzed the spread is much reduced we find a mean age of 65 4 0 7 ma for five flows near the base of the section jahwar and igatpuri formations and 65 2 0 4 ma for a dyke cross cutting the poladpur formation below the topmost mahabaleshwar formation this implies that at least 1800 m out of the 2500 m composite trap section were erupted in a short interval less than 1 ma long and close to 65 5 ma i e close to the cretaceous tertiary boundary we find that older ages near 67 ma found by several authors are essentially based on whole rock samples which display disturbed spectra when this can be checked i e when the spectra are published

a sequence of events across the cretaceous tertiary boundary the lithological and biological sequence of events across the cretaceous tertiary k t as developed in thick and complete landbased sections and termed the standard k t event sequence is also found in many i sdp cores from all over the globe microtektite like spherules have been found in almost every core or outcrop with an iridium anomaly forming a worldwide strewnfield these microtektites are an excellent indicator of the k t boundary level the basal paleocene globigerina eugubma zone is nov established in all major ocean basins the difference in faunas between the pacific and tethys atlantic oceans may point to different recovery of the oldest paleocene planktonic foraminiferal assemblages in different ocean basins planktonic foraminifera and nannoplankton apparently show a different extinction recovery pattern at the k t boundary which suggests that the nannoplankton underwent final extinction later and recover later than planktonic foraminifera these patterns may be important for the evaluation of the type and range of environmental stress resulting from the hypothesized impact s at the k t boundary blocking of sunlight by the dust cloud still can account for the clear mass mortality at the k t boundary but seems less likely as explanation for the final nannoplankton extinction as photosynthetic nannoplankton appear to survive 1000 10 000 years into the tertiary

the cretaceous tertiary boundary transition in the antarctic ocean and its global implications abstract three antarctic ocean k t boundary sequences from odp site 738c on the kerguelen plateau odp site 752b on broken ridge and odp site 690c on maud rise weddell sea have been analyzed for stratigraphic completeness and faunal turnover based on quantitative planktic foraminiferal studies results show that site 738c which has a laminated clay layer spanning the k t boundary is biostratigraphically complete with the earliest tertiary zones p0 and p1a present but with short intrazonal hiatuses site 752b may be biostratigraphically complete and site 690c has a hiatus at the k t boundary with zones p0 and p1a missing latest cretaceous to earliest tertiary planktic foraminiferal faunas from the antarctic ocean are cosmopolitan and similar to coeval faunas dominating in low middle and northern high latitudes although a few endemic species are present this allows application of the current low and middle latitude zonation to antarctic k t boundary sequences the most abundant endemic species is chiloguembelina waiparaensis which was believed to have evolved in the early tertiary but which apparently evolved as early as chron 30n at site 738c since this species is only rare in sediments of site 690c in the weddell sea this suggests that a watermass oceanographic barrier may have existed between the indian and atlantic antarctic oceans the cosmopolitan nature of the dominant fauna began during the last 200 000 to 300 000 years of the cretaceous and continued at least 300 000 years into the tertiary this indicates a long term environmental crisis that led to gradual elimination of specialized forms and takeover by generalists tolerant of wide ranging temperature oxygen salinity and nutrient conditions a few thousand years before the k t boundary these generalists gradually declined in abundance and species became generally dwarfed due to increased environmental stress there is no evidence of a sudden mass killing of the cretaceous fauna associated with a bolide impact at the k t boundary instead the already declining cretaceous taxa gradually disappear in the early danian and the opportunistic survivor taxa ch waiparaensis and guembelitria cretacea increase in relative abundance coincident with the evolution of the first new tertiary species

late cretaceous sea level changes in tunisia a multi disciplinary approach a multi disciplinary study of sea level and climate proxies including bulk rock and clay mineral compositions carbon isotopes total organic carbon toc sr ca ratios and macro and microfaunal associations reveals seven major sea level regressions in the southwestern tethys during the last 10 million years of the cretaceous late campanian c 74 2 ma 73 4 72 5 ma and 72 2 71 7 ma early maastrichtian 70 7 70 3 ma 69 6 69 3 ma and 68 9 68 3 ma and late maastrichtian 65 45 65 3 ma low sea levels are generally associated with increased terrigenous influx low kaolinite chlorite mica ratios high toc and high sr ca ratios whereas high sea levels are generally associated with the reverse conditions these sea level changes may be interpreted as eustatic as suggested by the global recognition of at least four of the seven major regressions identified 74 2 ma 70 7 70 3 ma 68 9 68 3 ma and 65 45 65 3 ma climatic changes inferred from clay mineral contents correlate with sea level changes warm or humid climates accompany high sea levels and cooler or arid climates generally accompany low sea levels

extended cretaceous tertiary boundary extinctions and delayed population change in planktonic foraminifera from brazos river texas high resolution planktonic foraminiferal analysis of three brazos river sections indicates a nearly continuous cretaceous tertiary k t boundary sedimentary record second only to the world s most complete record at el kef tunisia species extinctions occur over an extended period of time and with two major extinction episodes the first extinction episode with 46 of the species extinct occurs at and just below 10 15 cm a short hiatus at the base of a sandy shell hash and clay sand unit which was interpreted by bourgeois et al 1988 to represent a tsunami bed generated by the k t boundary bolide impact the top of this tsunami bed is about 17 20 cm below the k t boundary as defined by the first appearance of tertiary planktonic foraminifera the second extinction phase with 45 of the species extinct occurs 25 cm above the k t boundary zone p0 p1a boundary of the remaining seven surviving cretaceous species six gradually disappear during planktonic foraminiferal subzones p1a and basal p1b no species extinctions or major faunal assemblage changes are directly associated with the k t boundary iridium distribution is ambiguous with one peak in the upper part of the tsunami bed and a second peak at the micropaleontologically defined k t boundary relative abundances of dominant species are stable through the late maastrichtian and only minor abundance changes coincide with the first extinction episode or the k t boundary the first major faunal change in the dominant species group coincides with the second extinction episode and leads to decline and eventual extinction of this group in subzone p1a species disappearing at the two extinction episodes 46 and 45 constitute only a small percentage 8 and 5 of the individuals of the total planktonic foraminiferal population this suggests that weakened species with low numbers of individuals and sensitive to relatively minor environmental changes were primarily affected by these extinction episodes magnetostratigraphy indicates that the first extinction phase began about 310 000 years before the k t boundary and the second extinction phase occurred 50 000 years after the k t boundary this stepped pattern of species extinctions suggests a progressively stressed ecosystem in continental shelf settings which may be related to an observed sea level regression and global cooling the hypothesis of a global catastrophic mass extinction at the k t boundary caused by a large extraterrestrial impact is not supported by the brazos river planktonic foraminiferal data

constraining recent fault offsets with statistical and geometrical methods example from the jasneuf fault western alps france we propose two new approaches regarding recent fault offset measurements by studying the seismogenic potential of the jasneuf fault the ne trending right lateral strike slip jasneuf fault is the southwestern extension of the belledonne fault system in the vercors massif this fault which is located in an intraplate domain does not show strongly associated seismicity but displays morphological anomalies that are related to recent faulting right lateral offset of late cenozoic cliffs recent talwegs and post ganz scarps the two methods that we use to quantify fault slip are as follows 1 recursive measurements of stream offsets are conducted this analysis reveals that a stream network can display characteristic distances between streams that can be mistakenly interpreted as long term cumulative fault offsets a comparison of the apparent stream offset values and stream spacing values is necessary to identify the true offsets 2 we propose a new method that enables us to determine the fault offset and kinematics by using recursive measurements of topographic apparent offsets to counter the lack of morphologic features that are used to determine piercing points or lines this method enables us to define each possible slip vector for numerous artificial piercing points along a fault the slip vector that is shared by these piercing points is the true slip vector by applying these methodologies we determine that the jasneuf fault has accumulated slip since the messinian which corresponds to an average slip rate of 0 13 0 03 mm year the extension of the fault is poorly constrained nevertheless if we do not consider the potential aseismic creep slip component of the faulting we calculate that this fault could generate mw 5 7 earthquakes every similar to 500 years according to wells and coppersmith s scaling laws and by assuming that the faulting is limited to the sedimentary cover and the vercors plateau c 2016 elsevier b v all rights reserved

palaeoclimatic interpretation of clay minerals in marine deposits an outlook from the continental origin abstract as distribution of clay minerals in modern oceans seems to be controlled by contemporary climates marine clays in ancient deposits have been widely used to reconstruct palaeoclimates in this review we examine this question mainly from the continental origin of the clay minerals and show the difficulties of retrospective analysis of the influence of climate on common marine deposits we examine successively how soils develop and behave are reworked and palaeoweatherings are preserved focusing the review on kaolinitic soils indicative of tropical wet climates several stages intervene between the time of clay mineral development in soils and their final deposition in the basin 1 the persistence over geological times of huge amounts of kaolinitic palaeoweathering materials in the landscapes may seriously alter the palaeoclimatic signal of kaolinite in the sedimentary record although the kaolinite deposited in recent sediments of the world oceans is consistent with wet climatic zones this is mainly because the major kaolinitic and bauxitic palaeosurfaces coincide with the tropical areas where kaolinite is still developing at present 2 possible development of deep kaolinitic profiles at high latitudes and cold conditions under co 2 enriched palaeoatmospheres or even by unusual acidic weathering linked with dry climates is misleading palaeoenvironments for palaeoclimatic reconstruction 3 erosion and transport processes always cloud the signal to some extent because frequently erosion products from the bedrock and different soil horizons will be mixed and major drainage systems may include soils of different climatic zones 4 the arrival of the soil clay assemblages in the basin inevitably lags against their formation on the continent and may occur several million years after formation of the soils on the continent and climate may have considerably changed at that time it is pointed out that sedimentologists and palaeoclimatologists should consider the complexity of the relations between soil and sedimentary clay minerals soil formation rates are slow and therefore the resolution of the palaeoclimatic record in marine clay may not be closer than 1 or 2 ma at present the palaeoclimatic interpretations of marine clay assemblages are yielding at best nothing more than rather broad palaeoclimatic information this approach cannot achieve the same degree of resolution as other techniques such as isotope or microfossil studies clay mineral assemblages may provide integrated records of overall climatic impacts whereas other techniques are more likely to reveal local or temporary climates

rudist decline in the maastrichtian cardenas formation east central mexico abstract five sections of the cardenas and tabaco formations in east central mexico have been analyzed by means of bio sr isotope and sequence stratigraphy in order to evaluate their age as well as the timing of rudist decline ammonites pachydiscus pachydiscus neubergicus hauer sphenodiscus pleurisepta conrad coahuilites sheltoni bose indicate an early maastrichtian age for the topmost lower member of the cardenas formation and planktic foraminifera e g globotruncanita stuarti de lapparent archaeoglobigerina cretacea d orbigny globotruncanella petaloidea gandolfi gansserina gansseri bolli globotruncana linneiana d orbigny a late early maastrichtian age for the middle member corresponding to the foraminiferal zones cf5 and cf6 sr isotope stratigraphic data yield an early late maastrichtian age 66 93 ma 17 small scale and 3 large scale depositional cycles have been identified which correspond to para and depositional sequences the progradational pattern of the large scale cycles indicates an overall regression trend which terminated in subaerial exposure of the area indicated by paleosoils in the red beds of the tabaco formation the correlation of the large scale cycles with the global sea level charts indicate that eustatic sea level fall caused the regression and led to the exposure during the middle late maastrichtian this subaerial exposure resulted in the loss of habitat and thus the disappearance of rudists in east central mexico

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

fine grained debris flows and extraordinary vertebrate burials in the late cretaceous of madagascar vertebrate fossils are remarkably abundant and exceptionally well preserved within the upper cretaceous maevarano formation of northwestern madagascar the vast majority of these fossils including all of the currently known bone beds are entombed within deposits of fine grained cohesive debris flows these deposits are typically massive and are characterized by very poor sorting and a significant montmorillonite dominated silt clay mud fraction ranging from 17 to 46 by weight deposition is attributed to recurrent exceptional rainfall events that prompted erosion and flooded ancient channel belts with sediment laden flows these extraordinary burial events shielded vertebrate remains from destructive surface processes and also afforded protection for soft tissues taphonomic attributes of associated bone concentrations suggest that debris flows had limited transport potential and generally entombed subaerially exposed bone assemblages the remarkable and recurrent association of bone beds and debris flow deposits likely reflects marked seasonality in this late cretaceous terrestrial ecosystem with prolonged dry spells prompting mortality and subsequent rains setting debris flows in motion

age and paleoenvironment of the maastrichtian to paleocene of the mahajanga basin madagascar a multidisciplinary approach abstract lithology geochemistry stable isotopes and integrated high resolution biostratigraphy of the berivotra and amboanio sections provide new insights into the age faunal turnovers climate sea level and environmental changes of the maastrichtian to early paleocene of the mahajanga basin of madagascar in the berivotra type area the dinosaur rich fluvial lowland sediments of the anembalemba member prevailed into the earliest maastrichtian these are overlain by marginal marine and near shore clastics that deepen upwards to hemipelagic middle neritic marls by 69 6 ma accompanied by arid to seasonally cool temperate climates through the early and late maastrichtian an unconformity between the berivotra formation and betsiboka limestone marks the k t boundary and juxtaposes early danian zone plc or pld and latest maastrichtian zones cf2 cf1 micula prinsii sediments seasonally humid warm climates began near the end of the maastrichtian and prevailed into the early danian accompanied by increased volcanic activity during the late danian zones p1d p2 a change to seasonally arid climates was accompanied by deepening from middle to outer neritic depths

collision kinematics in the western external alps the kinematics of the collision in western alps are investigated through five balanced cross sections of the whole external domain from the oisans to the mont blanc massif these cross sections were built using published data for the jura and subalpine fold and thrust belts and new structural and field analysis for the external crystalline massifs five units are defined the sedimentary nappes from innermost parts of the external zone e g ultra dauphinois helvetic the crystalline units with their dysharmonically folded cover e g morcles nappe sedimentary nappes over the frontal parts of the crystalline massifs the aravis granier unit the subalpine belts e g vercors chartreuse bauges and bornes and the jura except for the ultra dauphinois nappes the shortening including the cover shortening always corresponds to basement shortening the total amount of shortening increases from south 28 km 20 to north 66 km 27 moreover the shortening is slightly older in the south than in the north deepwater turbidites flysch and shallow marine to freshwater clastics molasse basins are more developed in the north pressure and temperature conditions are higher in the north the average uplift rates are about 3 times higher in the north and more localized in space we propose that these differences are due to along strike variations in the structure of the european continental margin inherited from mesozoic times we then build five palinspastic maps one at cretaceous times showing the inherited european mesozoic margin structure and four from priabonian to upper miocene times showing the collision kinematics and the related rotation of adria

characterization of late campanian and maastrichtian planktonic foraminiferal depth habitats and vital activities based on stable isotopes abstract depth habitats of 56 late cretaceous planktonic foraminiferal species from cool and warm climate modes were determined based on stable isotope analyses of deep sea samples from the equatorial pacific dsdp sites 577a and 463 and south atlantic dsdp site 525a the following conclusions can be reached planoglobulina multicamerata de klasz and heterohelix rajagopalani govindan occupied the deepest plankton habitats followed by abathomphalus mayaroensis bolli globotruncanella havanensis voorwijk gublerina cuvillieri kikoine and laeviheterohelix glabrans cushman also at subthermocline depth most keeled globotruncanids and possibly globigerinelliodes and racemiguembelina species lived at or within the thermocline layer heterohelix globulosa ehrenberg and rugoglobigerina pseudotextularia and planoglobulina occupied the subsurface depth of the mixed layer and pseudoguembelina species inhabited the surface mixed layer however depth ranking of some species varied depending on warm or cool climate modes and late campanian or maastrichtian age for example most keeled globotruncanids occupied similar shallow subsurface habitats as rugoglobigerina during the warm late campanian but occupied the deeper thermocline layer during cool climatic intervals two distinct types of vital effect mechanisms reflecting photosymbiosis and respiration effects can be recognized by the exceptional 13c signals of some species 1 photosymbiosis is implied by the repetitive pattern of relatively enriched 13c values of racemiguembelina strongest planoglobulina rosita and rugoglobigerina species pseudoguembelina excolata weakest 2 enriched respiration 12c products are recognized in a mayaroensis gublerina acuta de klasz and heterohelix planata cushman isotopic trends between samples suggest that photosymbiotic activities varied between localities or during different climate modes and may have ceased under certain environmental conditions the appearance of most photosymbiotic species in the late maastrichtian suggests oligotrophic conditions associated with increased water mass stratification

stable isotope toc and caco3 record across the cretaceous tertiary boundary at el kef tunisia we report the results of stable oxygen and carbon isotope analysis of carbonate fine fraction and benthic and planktic foraminifers caco3 and toc determinations of sediments across the cretaceous tertiary k t boundary at el kef tunisia we used grain size analysis of the fine fraction carbonate to determine possible compositional effects and smearslide and scanning electron microscope examinations to evaluate possible diagenetic alteration and microfossil preservation the data suggests the following sequence of events upper maastrichtian oxygen and carbon isotope signals indicate relatively warm temperatures a decreasing thermal gradient possibly related to a shallowing sea and relatively high surface water productivity a sharp cooling appears to begin just below the k t boundary the k t boundary is characterized by a sudden 2 negative shift in fine fraction 13c a slight 0 6 enrichment in benthic 13c and a reduction of about 40 in caco3 sedimentation these data imply strongly reduced surface water productivity as also observed in numerous deep sea sequences worldwide the lower danian planktic foraminiferal zones p0 p1a is marked by generally low productivity and unstable environmental conditions as indicated by generally low but fluctuating fine fraction 13c values and low 5 15 carbonate deposition at the base of subzone p1b caco3 benthic and fine fraction 13c values increase gradually and reach near pre k t boundary levels in subzone p1c indicating initial recovery after the k t boundary event about 300 000 400 000 years after the k t boundary the prolonged low productivity episode after the k t crisis and the pre k t boundary cooling associated with a major reduction in planktic foraminiferal diversity are difficult to explain by a single k t boundary bolide impact

antarctic subtropical humid episode at the paleocene eocene boundary clay mineral evidence clay mineral assemblages from east antarctica have been analyzed at high stratigraphic resolution 20 to 1 ka throughout the interval from 55 6 to 55 0 ma which includes the terminal paleocene isotopic excursion in ocean drilling program site 690b on maud rise lat 65 s in the weddell sea region changes in the clay associations reflect a major increase in chemical weathering caused by increased temperature and or rainfall in at least this sector of east antarctica for a brief 270 ka interval in the latest paleocene this represents the most intense warming known for the cenozoic this high latitude climatic episode is recorded synchronously by stable isotopes and clay minerals a progression is evident in the clay assemblages during the latest paleocene that apparently reflects changing relations between temperature and precipitation this sequence began with the interval of rapid temperature increase that marks the beginning of the oxygen isotopic excursion a brief increase in kaolinite at the inception of the excursion suggests a temporary increase in year round precipitation in antarctica in response to an increased continent to ocean temperature gradient this kaolinite spike was followed by almost total dominance by smectite for the remainder of the isotopic excursion 120 ka suggesting that warmer southern ocean surface temperatures of 18 to 22 c were associated with seasonal precipitation alternating wet and dry seasons claymineral variations on antarctica during the isotopic excursion reflect a tight coupling between oceanic and continental climate change immediately following the excursion at 55 22 ma kaolinite percentages increased to values similar to modern subtropical tropical areas for 150 ka a remarkable event for the antarctic abundant kaolinite suggests perennial rainfall and minimum soil temperatures of 15 c during at least part of the year the kaolinite increased during a time of lower southern ocean surface water temperatures suggesting increased atmospheric heat transport toward the poles a temporary change in atmospheric circulation is suggested from dominantly zonal to meridional

biotic effects of the chicxulub impact k t catastrophe and sea level change in texas abstract biotic effects of the chicxulub impact the k t event and sea level change upon planktic foraminifera were evaluated in a new core and outcrops along the brazos river texas about 1000 km from the chicxulub impact crater on yucatan mexico sediment deposition occurred in a middle neritic environment that shallowed to inner neritic depths near the end of the maastrichtian the sea level fall scoured submarine channels which were infilled by a sandstone complex with reworked chicxulub impact spherules and clasts with spherules near the base the original chicxulub impact ejecta layer was discovered 45 60 cm below the sandstone complex and predates the k t mass extinction by about 300 000 years results show that the chicxulub impact caused no species extinctions or any other significant biotic effects the subsequent sea level fall to inner neritic depth resulted in the disappearance of all larger 150 m deeper dwelling species creating a pseudo mass extinction and a survivor assemblage of small surface dwellers and low oxygen tolerant taxa the k t boundary and mass extinction was identified 40 80 cm above the sandstone complex where all but some heterohelicids hedbergellids and the disaster opportunistic guembelitrids went extinct coincident with the evolution of first danian species and the global 13c shift these data reveal that sea level changes profoundly influenced marine assemblages in near shore environments that the chicxulub impact and k t mass extinction are two separate and unrelated events and that the biotic effects of this impact have been vastly overestimated

geodetic measurements of crustal deformation in the western mediterranean and europe geodetic measurements of crustal deformation over large areas deforming at slow rates 5 mm yr over more than 1000 km such as the western mediterranean and western europe are still a challenge because 1 these rates are close to the current resolution of the geodetic techniques 2 inaccuracies in the reference frame implementation may be on the same order as the tectonic velocities we present a new velocity field for western europe and the western mediterranean derived from a rigorous combination of 1 a selection of sites from the itrf2000 solution 2 a subset of sites from the european permanent gps network solution 3 a solution of the french national geodetic permanent gps network rgp and 4 a solution of a permanent gps network in the western alps regal the resulting velocity field describes horizontal crustal motion at 64 sites in western europe with an accuracy on the order of 1 mm yr or better its analysis shows that central europe behaves rigidly at a 0 4 mm yr level and can therefore be used to define a stable europe reference frame in that reference frame we find that most of europe including areas west of the rhine graben the iberian peninsula the ligurian basin and the corsica sardinian block behaves rigidly at a 0 5 mm yr level in a second step we map recently published geodetic results in the reference frame previously defined geodetic data confirm a counterclockwise rotation of the adriatic microplate with respect to stable europe that appears to control the strain pattern along its boundaries active deformation in the alps apennines and dinarides is probably driven by the independent motion of the adriatic plate rather than by the africa eurasia convergence the analysis of a global gps solution and recently published new estimates for the african plate kinematics indicate that the africa eurasia plate motion may be significantly different from the nuvel1a values in particular geodetic solutions show that the convergence rate between africa and stable europe may be 30 60 slower than the nuvelia prediction and rotated 10 30 counterclockwise in the mediterranean

early to late maastrichtian environmental changes in the indian ocean compared with tethys and south atlantic abstract planktic foraminiferal analysis including species populations diversity trends high stress indices and stable isotopes of the latest campanian through maastrichtian in the south atlantic tethys and indian oceans reveal four major climate and faunal events that ended with the cretaceous paleogene k pg formerly cretaceous tertiary k t mass extinction the prelude to these events is the late campanian cooling that reached minimum temperatures in the earliest maastrichtian base c31r correlative with low primary productivity and species diversity event 1 begins during the persistent cool climate of the early maastrichtian lower c31r when primary productivity rapidly increased accompanied by rapid species originations attributed to increased nutrient influx from increased upwelling erosion during the sea level fall 70 6 ma and ninety east ridge volcanism during event 2 upper c31r to lower c30n climate rapidly warmed by 2 3 c in deep waters and peaked at 22 c on land primary productivity remained high and diversification reached maximum for the entire cretaceous we attribute this climate warming to intense ninety east ridge volcanic activity beginning 69 5 ma accompanied by rapid reorganization of intermediate oceanic circulation enhanced greenhouse conditions due to the eruption of deccan phase 1 in india resulted in detrimental conditions for planktic foraminifera marking the end of diversification global cooling resumed in event 3 c30n species diversity declined gradually accompanied by dwarfing decreased large specialized species increased small ecologically tolerant taxa and ocean acidification event 3 is mainly the result of enhanced weathering and volcanogenic co2 adsorption by the oceans during the preceding warm event 2 that led to cooling and lower ph in the surface ocean event 4 marks the last 250 kyr of the maastrichtian c29r which began with the largest deccan eruptions phase 2 that caused rapid climate warming of 4 c in deep waters and 8 c on land acid rain and ocean acidification leading to a major carbonate crisis preceding the k t mass extinction

late maastrichtian paleoclimatic and paleoceanographic changes inferred from sr ca ratio and stable isotopes abstract milankovitch scale cycles can be recognized in high resolution 13c 18o sr ca mineralogical and magnetic susceptibility data in hemipelagic sediments that span the last 700 kyr of the maastrichtian at elles tunisia oxygen isotope data reveal three cool periods between 65 50 and 65 55 ma 21 5 23 5 m 65 26 and 65 33 ma 8 11 m and 65 04 and 65 12 ma 1 5 4 m and three warm periods between 65 33 and 65 38 ma 12 16 m 65 12 and 65 26 ma 4 8 m and 65 00 and 65 04 ma 0 1 5 m the cool periods are characterized by small surface to deep temperature gradients that reflect intensive mixing of the water column the surface to deep sr ca gradient generally correlates with the oscillating t trend temperature difference between surface and bottom waters the carbon isotope composition of planktonic foraminifera indicates a continuous decrease in surface bioproductivity during late maastrichtian decreasing 13c values difference between the 13c values of surface and bottom dwelling foraminifera and the carbon isotope ratios of the planktonic species at the onset of gradual warming at 65 50 ma reflect a reduction in surface productivity as a result of decreased upwelling that accompanied global warming and possibly increased atmospheric pco2 related to deccan trap volcanism time series analysis applied to magnetic susceptibility 18o and sr ca data identifies the 20 kyr precession 40 kyr obliquity and 100 kyr eccentricity milankovich cycles

abrupt deep sea warming at the end of the cretaceous climatic and oceanographic variations during the last 2 m y of the maastrichtian inferred from high resolution 10 k y stable isotope analysis of the mid latitude south atlantic deep sea drilling project site 525 reveal a major warm pulse followed by rapid cooling prior to the cretaceous tertiary boundary between 66 85 and 65 52 ma cool but fluctuating temperatures average 9 9 and 15 4 c in intermediate and surface waters respectively this interval is followed by an abrupt short term warming between 65 45 and 65 11 ma which increased temperatures by 2 3 c in intermediate waters and decreased the vertical thermal gradient to an average of 2 7 c this warm pulse may be linked to increased atmospheric pco 2 increased poleward heat transport and the switch of an intermediate water source from high to lowmiddle latitudes during the last 100 k y of the maastrichtian intermediate and surface temperatures decreased by an average of 2 1 and 1 4 c respectively compared to the maximum temperature between 65 32 and 65 24 ma

guembelitria dominated late maastrichtian planktic foraminiferal assemblages mimic early danian in central egypt abstract during the late maastrichtian 66 8 65 5 ma the asyut basin in central egypt experienced a breakdown of the surface to bottom gradient of the 13c 12c ratio with planktic 13c values 0 2 0 8 lighter than benthic values planktic foraminiferal species diversity was reduced by more than 50 with assemblages dominated 60 90 by the opportunistic blooms of the disaster species guembelitria cretacea which mimic the early danian the prolonged breakdown in productivity occurred during a time of tectonic activity and increased terrestrial runoff that may have resulted in highly eutrophic waters coupled with a sea level regression 65 5 ma that led to restricted circulation increased productivity during the short climate warming between 65 4 and 65 2 ma is associated with increased species diversity abundant rugoglobigerinids and common heterohelicids at the end of the maastrichtian decreased productivity coincided with the k t impact and mass extinction followed by characteristically early danian low diversity assemblages the similarity of the late maastrichtian and post k t impact guembelitria dominated assemblages reveals that the planktic foraminiferal response to the k t catastrophe was not unique but followed a predictable pattern of response to severe environmental perturbations

mechanisms of margin inversion in the external western alps implications for crustal rheology the kinematics of the collisional crustal wedge in the external western alps is discussed in the light of new cross sections of the whole external zone at the latitude of the belledonne grandes rousses oisans massifs external crystalline massifs ecm as well as a detailed analysis of the deformation of their basement and cover the cross sections were built from new field data and published geological maps and were restored through time oligo miocene times to unravel the successive stages of the dauphinois margin contractional deformation during oligocene times the variscan basement was deformed essentially by greenschist facies alpine distributed shear zones with no significant reactivation of the inherited jurassic normal faults or the variscan foliation however the inherited syn rift basins localized the deformation characterized by a thick skinned style and a cover disharmonically folded over basement shear zones with no major decollement in between shortening of 11 5 km 20 those early deformations progressively localized on the frontal crustal ramp and caused shortening in the folded belt 16 5 km of shortening 23 a similar sequence of deformation has been inferred in other alpine ecms this strongly suggests that the crust of dauphinois proximal passive margin was thin enough and its buoyancy low enough as a result of the liassic rifting to experience significant tectonic burial during the tertiary collision as a consequence of a weakening by both the presence of inherited basins and their weak syn rift sediments and the p t conditions greenschist facies the crust was shortened and the structural style was thick skinned

plio quaternary stress states in ne iran kopeh dagh and allah dagh binalud mountain ranges abstract ne iran including the kopeh dagh and allah dagh binalud deformation domains comprises the northeastern boundary of the arabia eurasia collision zone this study focuses on the evolution of the plio quaternary tectonic regimes of northeast iran we present evidence for drastic temporal changes in the stress state by inversion of both geologically and seismically determined fault slip vectors the inversions of fault kinematics data reveal distinct temporal changes in states of stress during the plio quaternary since 5 ma the paleostress state is characterized by a regional transpressional tectonic regime with a mean n140 10 e trending horizontal maximum stress axis 1 the youngest modern state of stress shows two distinct strike slip and compressional tectonic regimes with a regional mean of n030 15 e trending horizontal 1 the change from the paleostress to modern stress states has occurred through an intermediate stress field characterized by a mean regional n trending 1 the inversion analysis of earthquake focal mechanisms reveals a homogeneous transpressional tectonic regime with a regional n023 5 e trending 1 the modern stress state deduced from the youngest fault kinematics data is in close agreement with the present day stress state given by the inversions of earthquake focal mechanisms according to our data and the deduced results in northeast iran the arabia eurasia convergence is taken up by strike slip faulting along ne trending left lateral and nnw trending right lateral faults as well as reverse to oblique slip reverse faulting along nw trending faults such a structural assemblage is involved in a mechanically compatible and homogeneous modern stress field this implies that no strain and or stress partitioning or systematic block rotations have occurred in the kopeh dagh and allah dagh binalud deformation domains the plio quaternary stress changes documented in this paper call into question the extrapolation of the present day seismic and gps derived deformation rates over geological time intervals encompassing tens of millions of years

extinction dissolution and possible ocean acidification prior to the cretaceous paleogene k pg boundary in the tropical pacific abstract biotic perturbations and changes in ocean circulation during the maastrichtian stage of the latest cretaceous raise questions about whether the biosphere was preconditioned for the end cretaceous mass extinction of calcareous plankton a brief acme of inoceramid clams at 71 ma on shatsky rise in the tropical north pacific was followed by their extinction during the mid maastrichtian event at 70 1 ma associated with an abrupt warming of deep waters this was later followed by an interval of intense dissolution beginning 67 8 ma at odp site 1209 2387 m the late maastrichtian dissolution interval was initially gradual and is characterized by a low planktic benthic p b ratio highly fragmented planktic foraminifera mostly an absence of larger taxa low abundances of smaller taxa extremely low planktic foraminiferal numbers and low planktic foraminiferal and nannofossil species richness a partial recovery in carbonate preservation and calcareous plankton simple diversity began 250 kyr prior to the k pg boundary associated with the incursion of a younger more enriched 13c deep water mass although total abundances of planktic foraminifera in the sediment remained a tiny fraction of their earlier maastrichtian values a second brief dissolution event occurred 200 kyr before the boundary evidenced by renewed increase in planktic fragmentation but without a decrease in p b ratio our data show that changing deep water masses coupled with reduced productivity and associated decrease in pelagic carbonate flux was responsible for the first 1 6 myr dissolution interval while deccan traps volcanism may have caused surface ocean acidification 200 kyr prior to the k pg mass extinction event

intraplate seismicity new seismotectonic data in western europe abstract fault plane solutions for 128 earthquakes which occurred in france and neighbouring areas have been determined stress field information given by these data are discussed in relation to previous tectonic knowledge the western alps are characterized by a compressional regime with a fan shaped distribution of p axes which might be related to the interaction mechanism between europe and the adriatic plate the pyrenean region is mainly submitted to a south north compression tectonic activity in this area seems to be determined by the presence of two subduction zones with reverse dips in the south bay of biscay and in the central pyrenees the transition zone between these two active belts is characterized by significant seismicity with a transpression regime

maastrichtian climate productivity and faunal turnovers in planktic foraminifera in south atlantic dsdp sites 525a and 21 abstract stratigraphic faunal and isotopic analyses of the maastrichtian at dsdp sites 525a and 21 in the south atlantic reveal a planktic foraminiferal fauna characterized by two major events an early late maastrichtian diversification and end maastrichtian mass extinction both events are accompanied by major changes in climate and productivity the diversification event which occurred in two steps between 70 5 and 69 1 ma increased species richness by a total of 43 and coincided with the onset of major cooling in surface and bottom waters and increased surface productivity the onset of the terminal decline in maastrichtian species richness began at 67 5 ma and the first significant decline in surface productivity occurred at 66 2 ma coincident maximum cooling to 13 c in surface waters and the reduction of the surface to deep temperature gradient to less than 5 c major climatic and moderate productivity changes mark the mass extinction and the last 500 kyr of the maastrichtian between 200 and 400 kyr before the k t boundary surface and deep waters warmed rapidly by 3 4 c and cooled again during the last 100 kyr of the maastrichtian surface productivity decreased only moderately across the k t boundary species richness began to decline during the late maastrichtian cooling and by k t boundary time the mass extinction had claimed 66 of the species viewed within the context of maastrichtian climate and productivity changes the k t mass extinction could have resulted from extreme environmental stress even without the addition of an extraterrestrial impact

slip in the 1857 and earlier large earthquakes along the carrizo plain san andreas fault the moment magnitude mw 7 9 fort tejon earthquake of 1857 with a 350 kilometer long surface rupture was the most recent major earthquake along the south central san andreas fault california based on previous measurements of its surface slip distribution rupture along the 60 kilometer long carrizo segment was thought to control the recurrence of 1857 like earthquakes new high resolution topographic data show that the average slip along the carrizo segment during the 1857 event was 5 3 1 4 meters eliminating the core assumption for a linkage between carrizo segment rupture and recurrence of major earthquakes along the south central san andreas fault earthquake slip along the carrizo segment may recur in earthquake clusters with cumulative slip of 5 meters

aseismic deformation in the alps gps vs seismic strain quantification neotectonics of the western and central alps is characterized by ongoing widespread extension in the highest zones of the chain and transcurrent compressive tectonics at the external limits of the belt the overall geodetically measured deformations also indicate extension across the western alps there is a good qualitative coherency between seismotectonic and geodetic approaches here we attempt to quantify the seismic part of the deformation the seismic strain is compared to the deformation derived from geodesy in sub areas of homogeneous seismic stress strain we computed the total seismic moment tensor and related strain tensor this study provides new quantitative elements about the ongoing geodynamic processes in the alpine belt the important discrepancies obtained between seismic strains and geodetically measured deformations raise the issue of aseismic deformation in the alps which could be related to elastic loading creeping and or a slower ductile style deformation

variability in late cretaceous climate and deep waters evidence from stable isotopes abstract strong climatic and temperature fluctuations mark the late campanian and maastrichtian as indicated by stable isotope records from the equatorial pacific site 463 and middle and high latitude south atlantic sites 525 689 and 690 the first major global cooling decreased intermediate water temperatures iwt by 5 6 c between 73 70 ma at the same time sea surface temperature sst decreased by 4 5 c in middle and high latitudes intermediate waters iw temporarily warmed by 2 c in low and middle latitudes between 70 68 5 ma global cooling resumed between 68 5 65 5 ma when iwt decreased by 3 4 c and sst by 5 c in middle latitudes about 450 ka before the cretaceous tertiary boundary rapid global warming increased iwt and sst by 3 4 c though sst in the tropics changed little during the last 200 ka of the maastrichtian climate cooled rapidly with iwt and sst decreasing by 2 3 c during the global cooling at 71 70 ma and possibly at 67 65 5 ma the sources of cold intermediate waters in the equatorial pacific indo pacific and south atlantic were derived from the high latitude north pacific in contrast during the global climate warming between 65 2 65 4 ma the middle latitude south atlantic was closest to the source of iw production and implies that the low latitude tethys played a major role in global climate change climate changes sea level fluctuations and associated restricted seaways appear to be the most likely mechanisms for the alternating sources of iw production

nannofossil diversity and equitability and fine fraction δ13c across the cretaceous tertiary boundary at walvis ridge leg 74 south atlantic abstract the isotopic composition and diversity of nannofossils were studied in cores from the deep sea drilling project dsdp sites 525a 527 528 and 529 from the walvis ridge south atlantic to better understand the changes which occurred across the cretaceous tertiary boundary k t boundary the stratigraphic range of the samples is from thearkhangelskiella cymbiformis zone in the maastrichtian to theheliolithus kleinpelli zone in the danian nannofossil diversity was high shannon weaver diversity index h 2 5 3 in the late cretaceous but decreased sharply h 1 across the k t boundary the 13c values also decrease across the k t boundary at the four sites suggesting a reduction in surface productivity in the south atlantic concomitant with the reduction in diversity during the danian nannofossil diversity and 13c show some recovery approximately 500 700 k y after the boundary event however not until 2 5 ma after the boundary event did diversity become constant diversity values similar to those for the late cretaceous were not attained again in the early paleocene interval studied carbon isotopic compositions similar to those from the cretaceous were not attained until 4 5 ma after the k t event

stable isotope and foraminiferal changes across the cretaceous tertiary boundary at stevns klint denmark arguments for long term oceanic instability before and after bolide impact event abstract stable isotope and planktic and benthic foraminiferal analyses of the k t boundary transition at stevens klint denmark indicate a 100 500 kyr long period of instability in oceanic bottom water temperature and sea level during the latest maastrichtian from 2 7 m below and up to the k t boundary bottom water temperatures gradually cooled about 1 5 c as surface water temperatures remained constant at the k t boundary bottom water temperatures decreased additionally 3 c and then returned to pre boundary values just above the boundary interval coincident with the onset of the first temperature decrease there was a prominent sea level fall estimated between 50 100 m as observed in benthic and planktic foraminiferal assemblages as well as in a decreasing surface to bottom 13 c gradient about 40 cm below the iridium rich k t boundary clay sea level began to rise poor preservation of foraminifera above the k t boundary allows only tentative interpretation of danian events at stevns klint however sea level generally continued to rise interrupted by short sea level falls associated with the observed sea level changes are three important hiatuses at the contact between the white chalk and overlying grey white bryozoan chalk about 2 7 m below the k t boundary at or near the top of the fish clay zone pla parvularugoglobigerina eugubina missing and at the contact of the cerithium limestone and overlying bryozoan limestone about 60 cm above the k t boundary part of zone plc missing these unconformities are coeval with hiatuses observed in many continental shelf sections and indicate a global eustatic rather than regional isostatic response notable is that at stevns klint the episode of oceanic instability is registered over approximately the same stratigraphic interval in which supposed extraterrestrial amino acids occur a circumstance that may indicate a connection a gradual positive shift in 13 c is registered in both benthic and planktic foraminiferal assemblages in the upper maastrichtian at stevns klint the positive shift is followed by a prominent negative 13 c shift 1 3 at the k t boundary an upper maastrichtian positive 13 c excursion followed by a negative 13 c anomaly at or near the k t boundary has previously been observed in deep sea cores from the pacific ocean and the weddell sea antarctica implying a global event previous suggestions of a relation between the uppermost maastrichtian positive 13 c excursion and sea level variation are not supported by the data for stevns klint

morphogroups and small sized tests in pseudotextularia elegans rzehak from the late maastrichtian succession of meghalaya india as indicators of biotic response to paleoenvironmental stress abstract cretaceous paleocene shelf successions of therriaghat and mahadeo in meghalaya india preserve almost the whole of the late maastrichtian stage in which the warm water tethyan planktonic foraminifera pseudotextularia elegans rzehak occurs in the racemiguembelina fructicosa zone zone cf4 and pseudoguembelina palpebra zone zone cf2 as five distinct morphogroups a e morphogroups a c commonly occur in rocks representing the transgressive regime of the r fructicosa zone at therriaghat whereas that of p palpebra zone was conducive for morphogroup d in the deeper shelf around therriaghat and morphogroup e in the near shore shelf around mahadeo the absence of p elegans in the pseudoguembelina hariaensis zone zone cf3 is postulated due to tectonic cause whereas its absence in the plummerita hantkeninoides zone zone cf1 was due to regression analysis of growth parameters including length width thickness and angle of flaring of the tests of the species reveal that morphogroups b and c are generally larger in size than the other morphogroups and the test length of the meghalaya specimens is smallest over its world occurrences diverse morphogroups and small tests are unique in the species of meghalaya however the cause of such unusual growth is difficult to explain due to development close to the tectonically active deccan volcanic province and the assam arakan and himalayan mobile belts the meghalaya shelf had unusual biotic stress due to volcanic eruption sea level fluctuations induced by plate collision and climate warming and retreat of the neo tethys during the biozones cf4 and cf2 when vigorous deccan outbursts occurred p elegans developed diverse morphogroups and acquired small size tests to cope with the changed environments and possibly to increase its chances of avoiding by microspherule missiles

the cretaceous tertiary transition in guatemala limestone breccia deposits from the south peten basin limestone breccia deposits in southern mexico guatemala and belize have recently been interpreted as proximal to distal ballistic fallout deposits generated by a bolide impact that struck yucatan at k t boundary time we review the age lithology and the depositional environment of five k t boundary sections in the south peten area of guatemala caribe aserradero chisec actela chemal in order to evaluate the nature and origin of k t limestone breccia deposition the sections are located 500 km south of the proposed impact site at chicxulub and trend in an east west direction from the guatemala mexico border to southern belize in four of the five sections examined a breccia unit up to 50 m thick overlies reef bearing shallow water limestones of late cretaceous campanian maastrichtian age rhythmically bedded limestones marls and siltstones of early danian age overlie the breccia and were deposited under middle to outer neritic conditions the breccia consists of differently coloured layers of shallow water limestones clast size generally decreases upsection to thin layers of predominantly rounded clasts and these fine grained rudstones grade into grainstones at the top in at least one section ei caribe diagenetically altered glass spherules are present in the uppermost layers of the grainstone these glass spherules are of stratigraphic position and chemical composition similar to black and yellow glass from beloc haiti and mimbral mexico which some workers have chemically linked to melt glass within the breccia of the chicxulub cores we suggest that breccia deposition in guatemala may have been multi event over an extended time period and related to the collision of the yucatan and chortis plates as well as related to a major impact or volcanic event at the end of the cretaceous

horizontal shortening control of middle miocene marine siliciclastic accumulation upper marine molasse in the southern termination of the savoy molasse basin northwestern alps southern jura

decline of the maastrichtian pelagic ecosystem based on planktic foraminifera assemblage change implication for the terminal cretaceous faunal crisis an outer shelf upper slope tropical tethyan pelagic environment existed over southern israel during maastrichtian time planktic foraminifera in the 63 and 149 m size fractions from four sections in this area were studied quantitatively for a high resolution ecostratigraphic analysis of the pre cretaceous tertiary k t paleoenvironment during the maastrichtian 41 of the planktic foraminifera species became extinct mostly keeled globotruncanidae which also became quantitatively reduced near the end of the maastrichtian from as much as 35 to only 5 of the planktic foraminifera population evolutionary replacement of extinct species by new forms nearly ceased in that interval two major opportunistic blooms of guembelitria took place associated with reduced abundances of keeled forms and the dominant species heterohelix globulosa the first bloom occurred within the upper gansserina gansseri to lower abathomphalus mayaroensis zones and the second within the plummerita hantkeninoides zone the extinctions concomitant changes in faunal dominance and opportunist blooms indicate that the pelagic ecosystem in the negev area experienced multiple stresses during the maastrichtian the planktic foraminiferal assemblages were taxonomically impoverished and in decline prior to the k t boundary crisis

how complete are cretaceous tertiary boundary sections a chronostratigraphic estimate based on graphic correlation cogent interpretations of data bearing on the cretaceous tertiary k t extinction controversy depend on the existence of accurate chronostratigraphic models for the various k t boundary sections we have employed the graphic correlation technique to summarize biostratigraphic and lithostratigraphic data from 15 intensively sampled k t boundary sections within a common chronostratigraphic model our results indicate that almost all of these sections along with 13 additional boundary sections not used to construct the model contain prolonged and in many cases multiple hiatuses of these 28 boundary sections only six were found to contain a continuous record of sediment accumulation across the k t boundary itself these six k t complete sections are el kef tunisia agost spain caravaca spain and three sections along the brazos river texas a comparative analysis of hiatus distributions among these 28 k t boundary sections also reveals the presence of systematic differences between continental shelf and deep sea depositional environments the lower danian interval immediately following the k t boundary and extending into biochronozones p0 and p1a is typically missing from the deep sea whereas boundary sections deposited in shallower middle neritic to upper slope environments are in most cases complete across the k t boundary these shallow neritic boundary sections however are in many instances disrupted by hiatuses at the p0 p1a boundary and again in the upper part of zone p1a these differential patterns of hiatus distribution between deep sea and continental shelf depositional settings appear to be linked to sea level fluctuations our data suggest that the apparently sudden mass extinction of planktonic foraminifera and anomalies in the occurrence of geochemical tracers that are characteristic of the k t boundary in deep sea sections may be artifacts of a temporally incomplete deep sea stratigraphic record

damage due to the mw 7 7 kutch india earthquake of 2001 abstract this paper presents a study of the damage due to the m w 7 6 7 7 intraplate kutch earthquake of 26 january 2001 it was a powerful earthquake with a high stress drop of about 20 mpa aftershocks up to m 4 have continued for 2 5 years the distribution of early aftershocks indicates a rupture plane of 20 25 km radius at depths of 10 45 km along an e w trending and south dipping hidden fault situated approximately 25 km north of the kutch mainland fault the moment tensor solution determined from regional broadband data indicates reverse motion along a south dipping by 47 fault the earthquake is the largest event in india in the last 50 years and the most destructive in the recorded history in terms of socioeconomic losses with 13 819 deaths including 14 in pakistan collapse severe damage of over a million houses and us 10 billion economic loss surface faulting was not observed however intense land deformations have been observed in a 40 20 km meizoseismal area these include lateral spreading ground uplifts about a meter ground slumping and deep cracks liquefaction with ejection of sand and copious water was widespread in the banni grassland rann areas salt plains along rivers and also in the coastal areas up to 200 km distance from the epicenter in areas of intensity vii to x stray incidences of liquefaction have occurred up to distances of at least 300 km for the first time in india multistory buildings have been destroyed damaged by an earthquake the maximum acceleration is inferred to be 700 cm s 2 and intensities are 1 3 units higher in soil covered areas than expected from the decay rate of acceleration for hard rock

crustal velocity and strain rate fields in italy and surrounding regions new results from the analysis of permanent and non permanent gps networks summary we present a new geodetic velocity solution for italy and the surrounding areas obtained from an analysis of continuous and survey mode global positioning system observations collected between 1991 and 2002 we have combined local regional and global networks into a common reference frame velocity solution providing a new detailed picture of the regional scale deformation field in the central mediterranean our velocity estimates are computed with respect to a new stable eurasian reference frame constraining the kinematics of the greater african eurasian plate boundary system in the study area we provide strain rate values for the main seismotectonic districts which are in good agreement with the seismic deformation inferred from earthquake focal mechanisms the southern tyrrhenian area calabria the apennines the southeastern alps the southern dinarides and the albanides display deformation rates at the order of 20 30 nanostrain yr 1 the corsica sardinia block moves according to eurasian plate motions and there is no indication that the opening of the tyrrhenian is still active the pelagian and sicilian domains are separated by a northwest southeast discontinuity the sicily channel rifted area and marginally significant relative motion between the pelagian plateau and the african plate is also observed the southern tyrrhenian is affected by north south compression and accommodates up to 50 per cent of the africa eurasia relative plate motion whereas the calabrian arc exhibits 2 mm yr 1 northwest southeast extension the observed deformation pattern suggests the presence of a major approximately north south tectonic discontinuity separating the sicilian and calabrian domains an extensional boundary observed along peninsular italy coincides with the distribution of seismogenic faults along the axis of the apennines this boundary separates a tyrrhenian and an adriatic domain with diverging velocities orientated north nnw ward and northeastward respectively the apennines are extending perpendicularly to the chain axis at rates of less than 3 mm yr 1 and only in the outer northern apennines indications of active shortening are observed insignificant deformation is observed in the western po plain and the western alps while the central and eastern alps display north south shortening the eastern adriatic domain is shortening perpendicular to the dinaric front with strain rates increasing from north to south the locus of collision between the aegean balkan system and the adriatic and ionian domains is marked by the kephalonia fault system which accommodates up to 20 1 mm yr 1 of right lateral motion the deformation pattern observed in the peri adriatic domain is well described by a counter clockwise rotation of the adriatic microplate around a pole located in the western alps

geochemical evidence for suppression of pelagic marine productivity at the cretaceous tertiary boundary the normal biologically productive ocean is characterized by a gradient of the 13c 12c ratio from surface to deep waters here we present stable isotope data from planktonic and benthic micro fossils across the cretaceous tertiary boundary in the north pacific which reveal a rapid and complete breakdown in this biologically mediated gradient the fluxes of barium a proxy for organic carbon and caco3 also decrease significantly at the time of the major marine plankton extinctions the implied substantial reduction in oceanic primary productivity persisted for 0 5 myr before the carbon isotope gradient was gradually re established in addition the stable isotope and preservational data indicate that environmental change including cooling began at least 200 kyr before the cretaceous tertiary boundary and a peak warming of 3 c occurred 600 kyr after the boundary event

terminal cretaceous warming event in the mid latitude south atlantic ocean evidence from poleward migration of contusotruncana contusa planktonic foraminifera morphotypes abstract spatial and temporal patterns in test size and shape test conicity and spiral roundness and absolute abundance accumulation rate of the planktonic foraminifer contusotruncana contusa were studied in the south atlantic ocean dsdp sites 356 516 525 and 527 during an interval corresponding to the last 800 kyr of the cretaceous the variation in absolute abundance of c contusa was characterised by alternating periods of high and low abundance some of these periods were traceable across the entire mid latitude south atlantic ocean while the mean spiral roundness did not show any interpretable patterns a sudden increase of the mean test size and mean test conicity occurred between 65 3 and 65 2 ma based on linear interpolation within the cretaceous part of subchron c29r at all sites studied indicating a poleward migration followed by rapid withdrawal of the low latitude c contusa morphotypes from the mid latitude south atlantic ocean we suggest that this event was caused by a short period of surface water warming in the southern mid latitudes corresponding to the brief high latitude warming event and associated faunal migrations in the boreal and austral realms

disaster opportunists guembelitrinidae index for environmental catastrophes blooms of the disaster opportunist guembelitria species are proxies for environmental catastrophes whether impact or volcanism leading to severe biotic stress crises that may range from temporary exclusion of ecological specialists and generalists to mass extinctions during the late maastrichtian and early danian zones p0 and pla guembelitria blooms show global distributions but with the largest blooms 40 80 guembelitria in low and middle latitudes and only minor blooms 10 20 in high latitudes late maastrichtian guembelitria blooms are so far known from the indian ocean and eastern tethys the most intense guembelitria blooms 60 guembelitria occurred in shallow continental shelf areas slope shelf margins and volcanic provinces of the indian ocean what these environments have in common is high nutrient influx eutrophication either from continental runoff upwelling along continental margins or volcanic input at times of biotic crises guembelitria blooms may have spread rapidly to the exclusion of most or all other species much like today s red tides but with near global distributions a simple model can explain the ecological succession and recovery phases that follow major biotic perturbations caused by impacts or volcanism that lead to exclusion of specialist and most generalist species within such highly stressed environments guembelitria is the only genus to thrive and without competition rapidly reproduce and exponentially increase their populations when nutrients are depleted populations rapidly decrease leading to ecologic niches for other generalists and ecosystem recovery small low o2 tolerant heterohelicid populations mark this second stage followed by small trochospiral and planispiral species with further environmental recovery increasing competition niche development and restoration of a well stratified water mass oligotrophic conditions are restored opening habitats for the highly specialized and diverse species and a return to normal diverse assemblages this ecological succession is observed in association with mantle plume volcanism in the indian ocean and eastern tethys during the late maastrichtian and in association with the k t impact and volcanism during the early tertiary d 2004 elsevier b v all rights reserved

large river offsets and plio quaternary dextral slip rate on the red river fault yunnan china using multispectral spot images and 1 100 000 topographic data we present an improved map of the active red river fault zone between midu yunnan china and hanoi vietnam the fault zone is composed of parallel strands one of which the yuanjiang fault was previously undetected there also appears to be a component of extension all along the fault zone such extension increases toward the se from yunnan to the south china sea coast and the vector describing the motion of south china relative to indochina points within the n45 135 e quadrant we attempt to assess the plio quaternary dextral slip rate on the red river fault rrf by restoring large river offsets and searching for the largest plausible one across much of yunnan the fault is perpendicular to local catchments that drain into the red river from precise mapping of the river courses on spot satellite images and on 1 100 000 topographic maps numerous multiple offsets along the fault can be detected and reconstructed the lack of correlation between the apparent offsets and the lengths of the rivers upstream from the fault suggests either that the drainage system was in large part established prior to the onset of dextral slip along the fault or that frequent captures have occurred we thus try to find the best fit between series of river channels upstream and downstream from the fault by progressively restoring the dextral displacement in increments of 500 m up to an offset of 50 km for each increment we measure the misfits root mean squares rms between the upstream and downstream channels the best fit and smallest rms are obtained for an offset of 25 0 5 km that we interpret to represent the clearest large right lateral displacement recorded in the geomorphology along the active red river fault since dextral motion is likely to have started around 5 myr the most probable average plio quaternary slip rate on the fault is of order of 5 mm yr we attribute the apparent lack of seismic activity on a large stretch of the fault to millennial recurrence times between great earthquakes our study shows that relatively small drainage systems can keep a good record of fairly large cumulative fault offsets

lilliput effect in late maastrichtian planktic foraminifera response to environmental stress the lilliput effect marks morphologic and intraspecies size reductions in response to environmental stresses commonly associated with the aftermath of mass extinctions this study shows that the lilliput effect is a universal biotic response associated with greenhouse warming mesotrophic or restricted basins shallow marginal settings and volcanically active regions during the late maastrichtian sedimentary sequences analyzed from tunisia egypt texas argentina the south atlantic and indian ocean reveal that the biotic stress response appears uniform regardless of the cause varying only with the degree of biotic stress overall late maastrichtian environments span a continuum from optimum conditions to the catastrophic mass extinctions with a predictable set of biotic responses relative to the degree of stress induced by oxygen salinity temperature and nutrient variations as a result of climate and sea level changes and volcanism early stages of biotic stress result in diversity reduction and the elimination of large specialized species k strategists leading to morphologic size reduction via selective extinction disappearances and intraspecies dwarfing of survivors later stages of biotic stress result in the complete disappearance of k strategists intraspecies dwarfing of r strategists and dominance by low oxygen tolerant small heterohelicids at the extreme end of the biotic response are volcanically influenced environments which cause the same detrimental biotic effects as observed in the aftermath of the k t mass extinction including the disappearance of most species and blooms of the disaster opportunist guembelitria

reconstructing past sea surface temperatures correcting for diagenesis of bulk marine carbonate abstract a numerical model which describes oxygen isotope exchange during burial and recrystallization of deep sea carbonate is used to obtain information on how sea surface temperatures have varied in the past by correcting measured 18o values of bulk carbonate for diagenetic overprinting comparison of bulk carbonate and planktonic foraminiferal 18o records from odp site 677a indicates that the oxygen isotopic composition of bulk carbonate does reflect changes in sea surface temperature and 18o at odp site 690 we calculate that diagenetic effects are small and that both bulk carbonate and planktonic foraminiferal 18o records accurately reflect paleogene warming of high latitude surface oceans biased from diagenesis by no more than 1 c the same is likely to be true for other high latitude sites where sedimentation rates are low at dsdp sites 516 and 525 the effects of diagenesis are more significant measured 18o values of eocene bulk carbonates are more than 2 lower at deeply buried site 516 than at site 525 consistent with the model prediction that the effects of diagenesis should be proportional to sedimentation rate model corrections reconcile the differences in the data between the two sites the resulting paleotemperature reconstruction indicates a 4 c cooling of mid latitude surface oceans since the eocene at low latitudes the contrast in temperature between the ocean surface and bottom makes the carbonate 180 values particularly sensitive to diagenetic effects most of the observed variations in measured 18o values are accounted for by diagenetic effects rather than by sea surface temperature variations we show that the data are consistent with constant equatorial sea surface temperatures through most of the cenozoic with the possible exception of the early eocene when slightly higher temperatures are indicated we suggest that the lower equatorial sea surface temperatures for the eocene and oligocene reported in other oxygen isotope studies are artifacts of diagenetic recrystallization and that it is impossible to reconstruct accurately equatorial sea surface temperatures without explicitly accounting for diagenetic overprinting

stable isotope evidence for gradual environmental changes and species survivorship across the cretaceous tertiary boundary high resolution 13c and 18o records have been generated from analyses of the planktonic foraminiferal species heterohelix globulosa and the benthonic foraminiferal taxon lenticulina spp from 3 m of a cored section spanning the cretaceous tertiary k t boundary at brazos river texas these are the first stable isotope records across the k t boundary based on monospecific and monogeneric foraminiferal samples they show a gradual decrease in 13c values of about 2 5 permil beginning at the k t boundary as defined by the first appearance of tertiary planktonic foraminifera and continuing 17 20 cm above the boundary approximately 40 000 years later gradual 13c depletion contrasts with the sudden 13c drop at the k t boundary observed in many deep sea sections the surface to bottom 13c gradient decreased to less than zero approximately 25 000 30 000 years after the k t boundary and remained negative for at least the next 140 000 years concomitant with change in 13c values is a gradual decrease of about 2 5 permil in 18c values which has not been observed at other localities this 18o depletion suggests changes in temperature and or salinity in the earliest paleocene gulf of mexico no extinction of foraminiferal species is associated with the k t boundary or the onset of 18o and 13c depletions instead two phases of cretaceous species extinctions occur one extinction phase is below the k t boundary and below the tsunami bed of bourgeois et al 1988 and may be linked to sea level regression and environmental perturbations the second extinction phase coincides with the minimum in 13c and 18o values in the early danian zone p0 pla and appears directly related to environmental changes reflected in the isotopic record h globulosa which is commonly present in maastrichtian and danian sediments exhibits significantly lower 18o 16o and 13c 12c ratios in tertiary sediments relative to specimens from maastrichtian sediments demonstrating the survival of this important cretaceous taxon after the k t boundary event

stratigraphic analysis of upper cretaceous rocks in the mahajanga basin northwestern madagascar implications for ancient and modern faunas abstract upper cretaceous strata of the mahajanga basin northwestern madagascar yield some of the most significant and exquisitely preserved vertebrate fossils known from gondwana the sedimentology of these strata and their stratigraphic relations have been the focus of renewed geological investigations during the course of five expeditions since 1993 we here designate stratotypes and formalize the terrestrial maevarano formation with three new members masorobe anembalemba miadana and the overlying marine berivotra formation the maevarano formation accumulated on a broad semiarid alluvial plain bounded to the southeast by crystalline highlands and to the northwest by the mozambique channel the berivotra formation was deposited in an open marine setting that evolved from a clastic to a carbonate dominated shelf resulting in deposition of the overlying betsiboka limestone of danian age new stratigraphic data clearly indicate that the maevarano formation correlates at least in part with the

hiatus distributions and mass extinctions at the cretaceous tertiary boundary much disagreement over the interpretation of data bearing on various cretaceous tertiary k t extinction scenarios results from a failure to view these data within their appropriate stratigraphic context combined biostratigraphic and chronostratigraphic analyses of k t boundary sequences have revealed systematic differences in patterns of sediment accumulation within continental shelf and deep sea depositional settings although virtually all deep sea boundary sequences are marked by intervals of nondeposition or hiatus formation during the latest cretaceous and earliest tertiary many continental shelf slope sequences appear to be temporally complete over this same interval this differential pattern of sediment accumulation can be related to the latest maastrichtian earliest danian sea level rise during which deep sea sediment accumulation rates would be expected to drop as the locus of sediment deposition migrated across the continental shelf our data suggest that the abrupt shifts in carbon isotope abundances single peak ir anomalies and apparently instantaneous mass extinctions of marine plankton which are routinely reported from deep sea k t boundary sequences and used to support a causal relation between late cretaceous bolide impacts and k t mass extinctions may be artifacts of a temporally incomplete or extremely condensed deep sea stratigraphic record

deposition and age of chicxulub impact spherules on gorgonilla island colombia the end cretaceous mass extinction 66 ma has long been associated with the chicxulub impact on the yucatan peninsula however consensus on the age of this impact has remained controversial because of differing interpretations on the stratigraphic position of chicxulub impact spherules relative to the mass extinction horizon one side argues that the impact occurred precisely at the cretaceous paleogene boundary thus coinciding with the mass extinction the other side argues that the impact predated the cretaceous paleogene boundary based on the discovery of primary impact spherules deposits in ne mexico and texas near the base of planktic foraminiferal zone cf1 dated at 170 k y before the cretaceous paleogene boundary a recent study of the most pristine chicxulub impact spherules discovered on gorgonilla island colombia suggested that they represent a primary impact deposit with an absolute age indistinguishable from the cretaceous paleogene boundary here we report on the gorgonilla section with the main objective of evaluating the nature of deposition and age of the spherule rich layer relative to the cretaceous paleogene boundary the gorgonilla section consists of light gray yellow calcareous siliceous mudstones pelagic deposits alternating with dark olive brown litharenites turbidites a 3 cm thick dark olive green spherule rich layer overlies an erosional surface separating maastrichtian and danian sediments this layer consists of a clast supported normally graded litharenite with abundant chicxulub impact glass spherules lithics mostly volcanic and maastrichtian as well as danian microfossils which transitions to a calcareous mudstone as particle size decreases mineralogical analysis shows that this layer is dominated by phyllosilicates similar to the litharenites turbidites that characterize the section based on these results the spherule rich layer is interpreted as a reworked early danian deposit associated with turbiditic currents a major hiatus 250 k y spanning the cretaceous paleogene boundary and the earliest danian is recorded at the base of the spherule rich layer based on planktic foraminiferal and radiolarian biostratigraphy and carbon stable isotopes erosion across the cretaceous paleogene boundary has been recorded worldwide and is generally attributed to rapid climate changes enhanced bottom water circulation during global cooling sea level fluctuations and or intensified tectonic activity chicxulub impact spherules are commonly reworked and redeposited into younger sediments overlying a cretaceous paleogene boundary hiatus of variable extent in the caribbean central america and north atlantic while primary deposits are rare and only known from ne mexico and texas because of their reworked nature gorgonilla spherules provide no stratigraphic evidence from which the timing of the impact can be inferred

extinction survivorship and evolution of planktic foraminifera across the cretaceous tertiary boundary at el kef tunisia an expanded sediment record at el kef shows that the k t boundary extinctions of planktic foraminifera extend over an interval from 25 cm below the geochemical boundary ir anomaly to 7 cm above species extinctions appear sequential with complex large ornate forms disappearing first and smaller less ornate forms surviving longer the 14 species extinctions below the boundary appear unrelated to an impact event cretaceous species survivorship is greater than previously assumed about 10 species survive 22 into subzone p1a globigerina eugubina all cretaceous survivors are small primitive forms which are generally smaller than their ancestors in cretaceous sediments species evolution after the k t event occurs in two pulses the first new paleocene species evolve in the basal black clay zone po immediately after the major cretaceous extinctions evolving species are small and primitive similar to cretaceous survivors the second pulse in species evolution occurs in the lower part of subzone p1b with the appearance of larger more diverse species the first major increase in carbonate sedimentation and productivity occurs at this time and signals the recoveyr of the ecosystem nearly 300 000 years after the k t event the species extinctions prior to the generally assumed impact event implied by the ir anomaly and the long recovery period of the ecosystem thereafter cannot be explained by a single impact but suggest that multiple causes may be responsible such as climatic changes volcanism a sea level drop production of warm saline bottom water and the chemical consequences associated with increased salinity

biotic effects of late maastrichtian mantle plume volcanism implications for impacts and mass extinctions abstract during the late maastrichtian dsdp site 216 on ninetyeast ridge indian ocean passed over a mantle plume leading to volcanic eruptions islands built to sea level and catastrophic environmental conditions for planktic and benthic foraminifera the biotic effects were severe including dwarfing of all benthic and planktic species a 90 reduction in species diversity exclusion of all ecological specialists near absence of ecological generalists and dominance of the disaster opportunist guembelitria alternating with low o2 tolerant species these faunal characteristics are identical to those of the k t boundary mass extinction except that the fauna recovered after site 216 passed beyond the influence of mantle plume volcanism about 500 kyr before the k t boundary similar biotic effects have been observed in madagascar israel and egypt the direct correlation between mantle plume volcanism and biotic effects on ninetyeast ridge and the similarity to the k t mass extinction which is generally attributed to a large impact reveal that impacts and volcanism can cause similar environmental catastrophes this raises the inevitable question are mass extinctions caused by impacts or mantle plume volcanism the unequivocal correlation between intense volcanism and high stress assemblages necessitates a review of current impact and mass extinction theories

active tectonics of the adriatic region from gps and earthquake slip vectors 1 to investigate the kinematics of the adriatic region we integrate continuous and episodic gps measurements with mw 4 5 earthquake slip vectors selected from the regional centroid moment tensor catalogue coherent motion of gps sites in the po valley in apulia and in the hyblean plateau allows us to estimate geodetically constrained angular velocities for these regions the predictions of the gps inferred angular velocities are compared with the earthquake slip vectors showing that the seismically expressed deformation at the microplate boundaries is consistent with the observed geodetic motion the remarkable consistency between geodetic seismological and geological evidence of active tectonics suggests that active deformation in the central adriatic is controlled by the relative motion between the adria and apulia microplates the microplates angular rotation rates are then compared with the rotation rates calculated with a simple block model supporting the hypotheses 1 that apulia forms a single microplate with the ionian sea and possibly with the hyblean region and 2 that adria and apulia rotate in such a way as to accommodate the eurasia nubia relative motion we suggest that the present day microplate configuration follows a recent fragmentation of the adriatic promontory that during the neogene rigidly transferred the africa motion to the orogenic belts that now surround the adriatic region

mass wasting and hiatuses during the cretaceous tertiary transition in the north atlantic relationship to the chicxulub impact deep sea sections in the north atlantic are claimed to contain the most complete sedimentary records and ultimate proof that the chicxulub impact is cretaceous tertiary boundary ktb in age and caused the mass extinction a multi disciplinary study of north atlantic dsdp sites 384 386 and 398 based on high resolution planktonic foraminiferal biostratigraphy carbon and oxygen stable isotopes clay and whole rock mineralogy and granulometry reveals the age stratigraphic completeness and nature of sedimentary disturbances results show a major hiatus across the ktb at site 384 with zones cf1 p0 and p1a missing spanning at least 540 ky similar to other north atlantic and caribbean localities associated with tectonic activity and gulf stream erosion at sites 386 and 398 discrete intervals of disturbed sediments with mm to cm thick spherule layers have previously been interpreted as the result of impact generated earthquakes at the ktb destabilizing continental margins prior to settling of impact spherules however improved age control based on planktonic foraminifera indicates spherule deposition in the early danian zone p1a 2 upper parvularugoglobigerina eugubina zone more than 100 ky after the ktb at site 386 two intervals of white chalk contain very small 63 m early danian zone p1a 2 assemblages 65 and common reworked cretaceous 35 species in contrast the in situ red brown and green abyssal clays of this core are devoid of carbonate in addition high calcite mica and kaolinite and upward fining are observed in the chalks indicating downslope transport from shallow waters and sediment winnowing via distal turbidites at site 398 convoluted red to tan sediments with early danian and reworked cretaceous species represent slumping of shallow water sediments as suggested by dominance of mica and low smectite compared to in situ deposition we conclude that mass wasting was likely the result of earthquakes associated with increased tectonic activity in the caribbean and the iberian peninsula during the early danian well after the chicxulub impact

tropical atlantic moisture flux convection over northeastern brazil and pertinence of the pirata network abstract this study aims to examine the relationship between the tropical atlantic latent heat flux and convective cloud coverage over northeast brazil neb during the four months of the main rainy season february may the correlation with anomalies of these data is investigated both without lag and with a 1 month lag the heat flux in advance in both cases a significant positive correlation appears in the northwestern tropical atlantic and a significant negative correlation is obtained for a limited area off eastern neb these two correlation patterns are linked to anomalies in the trade wind intensity and in the meridional position of the intertropical convergence zone itcz which relate to the latent heat flux anomalies and neb convective coverage anomalies respectively the positive correlation pattern is spread over a large part of the northern tropical atlantic whereas the negative correlation pattern is confined off neb this indicates the existence of different regional mechanisms in t

current strain regime in the western alps from continuous global positioning system measurements 1996 2001 four to six years of continuous measurements at 10 permanent global positioning system sites in the western alps show horizontal residual velocities of 2 mm yr with respect to stable europe uncertainties range from 0 3 to 1 4 mm yr these velocities and the associated strain rate field indicate that the central part of the range is currently dominated by east west extension whereas the southern part shows north south to northwest southeast compression the geodetic and seismotectonic data are consistent with a model where strain is essentially controlled by the counterclockwise rotation of the adriatic microplate with respect to eurasia this rotation together with the arcuate shape of the contact between the adriatic microplate and the alps induces dextral shear kinematic boundary conditions across the western alps with an additional divergence component in their central part and in switzerland and a convergence component in their southern part

late maastrichtian early danian sea level changes at gebel tawil shihaq in central jordan implications of chemostratigraphy and foraminiferal biostratigraphy abstract integrated foraminiferal and geochemical analyses of the upper maastrichtian lower danian succession of the gebel tawil shihaq section in the central jordan plateau has been conducted to interpret the nature of that succession within a sequence stratigraphic context the studied succession covers the interval of the cf4 p1c planktonic foraminiferal zones the incorporation of foraminiferal and geochemical proxies led to the recognition of four 3rd order depositional sequences three in the maastrichtian m sq1 m sq2 and m sq3 and one in the danian d sq1 these depositional sequences are bounded by four sequence boundaries detected based on abrupt faunal e g zonal interruption foraminiferal turnover and geochemical e g dolomitization sr ca and nearby ti al maxima mn and caco3 minima shifts based on the paleodepth variation revealed from the foraminiferal analyses and the consistent behavior of the different geochemical proxies a relative sea level curve was established and consequently the systems tracts of each depositional sequence were recognized the development of the inferred relative sea level curve reveals the twofold control of both global sea level changes and regional tectonics the latter resulted in amalgamation and elimination or modification of some sea level cycles relative to the previously recognized eustatic schemes at the cretaceous paleogene k pg boundary a highly agitated phosphatized event bed is intercalated and exposes distinctive unique lithological geochemical and biostratigraphical characteristics denoting a long lasting period of non deposition and erosion commonly interrelated to the tectonic impact of the syrian arc orogeny sao

global climate change and planktic foraminiferal response in the maastrichtian 1 the lengthy warm stable climate of the cretaceous terminated in the campanian with a cooling trend interrupted in the early and latest maastrichtian by two events of global warming at 70 68 ma and at 65 78 65 57 ma these climatic oscillations had a profound effect on pelagic ecosystems especially on planktic foraminiferal populations here we compare biotic responses in the tropical subtropical tethyan open ocean and mesotrophic zin valley israel and oligotrophic tunisia slopes which correlate directly with global warming and cooling the two warming events coincide with blooms of guembelitria an extreme opportunist genus best known as the main survivor of the cretaceous paleogene k pg catastrophe in the maastrichtian guembelitria bloomed in the uppermost surface water above shelf and slope environments but failed to reach the open ocean as it did at k pg the coldest interval of the late maastrichtian 68 65 78 ma is marked by an acme of the otherwise rare species gansserina gansseri a deep dwelling keeled globotruncanid the g gansseri acme event can be traced from the deep ocean even onto the tethyan slope marking copious production and circulation of cold intermediate water this acme is abruptly terminated by extinction of the species a dramatic reversal attributed to a short term global warming episode this extinction corresponds precisely with the second bloom of guembelitria that began 300 kyr prior to the k pg event the antithetical relationship between blooming of guembelitria and the g gansseri acme reflects planktic foraminiferal sensitivity to warm cool warm cool climatic oscillations marking the end of the cretaceous

gradual mass extinction species survivorship and long term environmental changes across the cretaceous tertiary boundary in high latitudes stable isotope and planktic foraminiferal analyses across the cretaceous tertiary k t boundary transition at nye klov indicate longterm oceanic instability associated with global sea level fluctuations a gradual mass extinction and decreased magnitude of the 13 c shift in high latitudes oceanic instability which began at least 100 kyr before the k t boundary and continued for about 300 kyr into the tertiary was accompanied by a gradual faunal turnover the maximum sea level lowstand during latest maastrichtian is recorded about 75 cm below the k t boundary a sea level rise first in evidence at 20 cm to 40 cm below the boundary continued into zone p0 boundary clay this sea level rise was accompanied by 2 c of cooling in surface and bottom waters prior to the k t boundary 13 c values remained relatively stable up to 10 cm below the k t boundary a negative shift of 0 5 to 1 0 per mil occurred in the boundary clay in both planktic and benthic foraminifera the surface to deep 13 c gradient remained nearly unchanged in contrast to low latitudes where this gradient is virtually eliminated no sudden mass extinction occurred in this cosmopolitan high latitude fauna and nearly all cretaceous taxa thrived well into the tertiary when they gradually disappeared shallow seas dominated by cretaceous survivor taxa and a well developed oxygen minimum zone prevailed during the earliest tertiary short term sea level lowstands are marked by hiatuses at the top of zones p0 and p1a about 50 kyr and 230 kyr after the k t boundary respectively rising sea level reestablished normal marine conditions about 300 kyr to 350 kyr after the k t boundary coincident with the first post k t boundary recovery of the tertiary fauna and extinction of cretaceous survivors during this time high latitude regions temporarily acted as centers of origin and dispersal for planktic foraminifera long term oceanic instability gradual faunal turnover absence of a sudden mass extinction and greatly diminished 13 c shift in high latitudes suggest that a k t boundary bolide impact was not the primary cause for the k t boundary faunal transition moreover these data strongly imply that the destructive effects of the bolide impact would have been greatest in low latitudes and negligible in high latitudes

paleoecology of the cretaceous tertiary mass extinction in planktonic foraminifera abstract paleobiogeographic patterns of the cretaceous tertiary k t mass extinction in planktonic foraminifera in tunisia spanning environments from open marine upper bathyal to shelf and shallow marginal settings indicate a surprisingly selective and environmentally mediated mass extinction this selectivity is apparent in all of the environmental proxies used to evaluate the mass extinction including species richness ecological generalists ecological specialists surface and subsurface dwellers whether based on the number of species or the relative percent abundances of species the following conclusions can be reached for shallow to deep environments about three quarters of the species disappeared at or near the k t boundary and only ecological generalists able to tolerate wide variations in temperature nutrients salinity and oxygen survived among the ecological generalists heterohelicids guembelitrids hedbergellids and globigerinellids only surface dwellers survived ecological generalists which largely consisted of two morphogroups of opportunistic biserial and triserial species also suffered selectively biserials thrived during the latest maastrichtian in well stratified open marine settings and dramatically declined in relative abundances in the early danian triserials thrived only in shallow marginal marine environments or similarly stressed ecosystems during the latest maastrichtian but dominated both open marine and restricted marginal settings in the early danian this highly selective mass extinction pattern reflects dramatic changes in temperature salinity oxygen and nutrients across the k t boundary in the low latitude tethys ocean which appear to be the result of both long term environmental changes e g climate sea level volcanism and short term effects bolide impact

source parameters of the 11 june 1909 lambesc provence southeastern france earthquake a reappraisal based on macroseismic seismological and geodetic observations 1 destructive earthquakes are rare in france yet pose a sizable seismic hazard especially when critical infrastructures are concerned only a few destructive events have occurred within the instrumental period the most important being the 11 june 1909 lambesc provence earthquake with a magnitude estimated at 6 2 rothe 1942 the event was recorded by 30 observatories and produced intensity ix effects in the epicentral area 30 km north of marseille we collected 30 seismograms leveling data and earthquake intensities to assess the magnitude and possibly the focal mechanism of this event following this multidisciplinary approach we propose a source model where all relevant parameters are constrained by at least two of the input data sets our reappraisal of the seismological data yielded mw 5 7 6 1 6 0 preferred and ms 6 0 consistent with the magnitude from intensity data me 5 8 and with constraints derived from modeling of coseismic elevation changes hence we found the lambesc earthquake to have been somewhat smaller than previously reported our data sets also constrain the geometry and kinematics of faulting suggesting that the earthquake was generated by reverse right lateral slip on a wnw striking steeply north dipping fault beneath the western part of the trevaresse fold this result suggests that the fold located in front of the luberon thrust plays a significant role in the region s recent tectonic evolution the sense of slip obtained for the 1909 rupture also agrees with the regional stress field obtained from earthquake focal mechanisms and microtectonic data as well as recent gps data

evidence for thermohaline circulation reversals controlled by sea level change in the latest cretaceous fluctuations in oxygen 18 o and carbon 13 c isotope values of benthic foraminiferal calcite from the tropical pacific and southern oceans indicate rapid reversals in the dominant mode and direction of the thermohaline circulation during a 1 m y interval 71 70 ma in the maastrichtian at the onset of this change benthic foraminiferal 18 o values increased and were highest in low latitude pacific ocean waters whereas benthic and planktic foraminiferal 13 c values decreased and benthic values were lowest in the southern ocean subsequently benthic foraminiferal 18 o values in the indo pacific decreased and benthic and planktic 13 c values increased globally these isotopic patterns suggest that cool intermediate depth waters derived from high latitude regions penetrated temporarily to the tropics the low benthic 13 c values at the southern ocean sites however suggest that these cool waters may have been derived from high northern rather than high southern latitudes correlation with eustatic sea level curves suggests that sea level change was the most likely mechanism to change the circulation and or source s of intermediate depth waters we thus propose that oceanic circulation during the latest cretaceous was vigorous and that competing sources of intermediate and deep water formation linked to changes in climate and sea level may have alternated in importance

analysis of geological hiatus surfaces across africa in the cenozoic and implications for the timescales of convectively maintained topography geological maps are a powerful but underutilized tool for constraining geodynamic processes and models unraveling the cenozoic elevation history of africa and distinguishing between competing upli

biotic effects of impacts and volcanism the biotic effects of late maastrichtian mantle plume volcanism on ninetyeast ridge and deccan volcanism mirror those of the cretaceous tertiary kt mass extinction and impact event planktonic foraminifera responded to high stress conditions with the same impoverished and small sized species assemblages dominated by the disaster opportunists guembelitria cretacea which characterize the kt mass extinction worldwide similar high stress late maastrichtian assemblages have recently been documented from madagascar israel and egypt biotic effects of volcanism cannot be differentiated from those of impacts though every period of intense volcanism is associated with high stress assemblages this is not the case with every impact the most catastrophic biotic effects occurred at the kt boundary 65 0 ma when intense deccan volcanism coincided with a major impact and caused the mass extinction of all tropical and subtropical species the chicxulub impact which now appears to have predated the kt boundary by about 300 kyr coincided with intense deccan volcanism that resulted in high biotic stress and greenhouse warming but no major extinctions the unequivocal connection between intense volcanism and high stress assemblages during the late maastrichtian to early danian and the evidence of multiple impacts necessitates revision of current impact and mass extinction theories

recent state of stress change in the walker lane zone western basin and range province united states the nw to north trending walker lane zone wlz is located along the western boundary of the northern basin and range province with the sierra nevada this zone is distinguished from the surrounding basin and range province on the basis of irregular topography and evidence for both normal and strike slip holocene faulting inversion of slip vectors from active faults historic fault offsets and earthquake focal mechanisms indicate two distinct quaternary stress regimes within the wlz both of which are characterized by a consistent wnw 3 axis these are a normal faulting regime with a mean 3 axis of n85 9 w and a mean stress ratio r value r 2 1 3 1 of 0 63 0 74 and a younger strike slip faulting regime with a similar mean 3 axis n65 70 w and r values ranging between 0 1 and 0 2 this younger regime is compatible with historic fault offsets and earthquake focal mechanisms both the extensional and strike slip stress regimes reactivated inherited mesozoic and cenozoic structures and also produced new faults the present day strike slip stress regime has produced strike slip normal oblique slip and normal dip slip historic faulting previous workers have explained the complex interaction of active strike slip oblique and normal faulting in the wlz as a simple consequence of a single stress state with a consistent wnw 3 axis and transitional between strike slip and normal faulting maximum horizontal stress approximately equal to vertical stress or r 0 in both regimes with minor local fluctuations the slip data reported here support previous results from owens valley that suggest deformation within temporally distinct normal and strike slip faulting stress regimes with a roughly constant wnw trending 3 axis zoback 1989 a recent change from a normal faulting to a strike slip faulting stress regime is indicated by the crosscutting striae on faults in basalts 300 000 years old and is consistent with the dominantly strike slip earthquake focal mechanisms and the youngest striae observed on faults in plio quaternary deposits geologic control on the timing of the change is poor it is impossible to determine if there has been a single recent absolute change or if there is rather an alternating or cyclical variation in stress magnitudes our slip data in particular the cross cutting normal and strike slip striae on the same fault plane are inconsistent with postulated simple strain partitioning of deformation within a single regional stress field suggested for the wlz by wesnousky and jones 1994 the location of the wlz between the deep seated regional extension of the basin and range and the right lateral strike slip regional tectonics of the san andreas fault zone is probably responsible for the complex interaction of tectonic regimes in this transition zone in early to mid tertiary time the wlz appears to have had a similarly complex deformational history in this case as a back arc or intra arc region accommodating at least part of the right lateral component of oblique convergence as well as a component of extension

high resolution planktonic foraminiferal analysis from the cretaceous tertiary boundary at ain settara tunisia evidence of an extended mass extinction the ain settara section located in the kalaat senan area of north central tunisia spans the cretaceous tertiary k t boundary which is characterized by a red layer and a thin non bioturbated boundary clay sediment accumulation across the k t boundary at ain settara was probably interrupted by three short hiatuses and or condensed sedimentation the first hiatus occurs at the top of the cf1 zone the second hiatus condensation occurred just below the boundary clay and the third hiatus at the p0 p1a boundary in the earliest danian these hiatuses are marked by weak unconformities bioturbation and sudden disappearances appearances of species which are known to disappear evolve sequentially in continuous sections quantitative high resolution planktonic foraminiferal analysis across zones cf1 upper p0 and p1a 1 reveals an extended and selective mass extinction all 41 of the species which disappeared at or below the k t boundary are rare to very rare and primarily ecologically specialized keeled deeper dwelling tropical subtropical forms globotruncana globotruncanita gublerina planoglobulina rosita contusotruncana racemiguembelina their combined relative abundance varies between 10 and 15 of the total population at the end of the maastrichtian the k t crisis thus appears more catastrophic when viewed in tropical subtropical assemblages and based on analysis of larger species 200 m which preferentially includes the more specialized forms though in fact the k t mass extinction actually involved a relatively small part of the foraminiferal population in terms of relative abundance the pattern of extinction and changes in dominant population at ain settara appear to be very similar to the planktonic foraminiferal turnover of the other north central tunisian sections el kef elles the selective mass extinction pattern suggests that the catastrophic effects of the bolide impact superimposed those related to long term environmental changes such as variations in temperature sea level and associated water mass changes

productivity across the cretaceous tertiary boundary in high latitudes in low and middle latitudes the cretaceous tertiary boundary is marked by a sudden and pronounced decrease in 13c values of near surface water carbonates and a reduction in the surface to bottom 13c gradient these isotopic data have been interpreted as evidence of a decline in surface water productivity that was responsible for the extinction of many planktic foraminiferal species and other marine organisms at or near the k t boundary we present planktic and benthic foraminiferal isotopic data from two almost biostratigraphically complete sections at ocean drilling program site 738 in the antarctic indian ocean and at nye klov in denmark these data suggest that planktic carbonate 13c values in high latitudes may not have decreased dramatically at the k t boundary thus surface water productivity may not have been reduced as much as in low and middle latitudes comparison of the records of site 738 with those of odp sites 690 and 750 indicates a pronounced decline in 13c values of planktic and benthic foraminifera and fine fraction bulk carbonate 200 000 yr after the k t boundary this reflects a regional shift in the carbon isotopic composition of oceanic total dissolved carbon tdc and correlates with a similar change in benthic foraminiferal 13c values at mid and low latitude deep sea drilling project sites 527 and 577 this oceanographic event was followed by the ecosystem s global recovery 500 000 yr after the k t boundary these data suggest that the environmental effects of the k t boundary may have been less severe in the high latitude oceans than in tropical and subtropical regions

preliminary comparison of ancient bole beds and modern soils developed upon the deccan volcanic basalts around pune india potential for palaeoenvironmental reconstruction abstract relict weathering mantles are frequently preserved in the form of paleosols which generally document the long term evolution of earth surface processes bole beds occur as prominent horizons composed of fine grained clayey or earthy material having colors in shades of red to chocolate brown green purple or gray often marking the flow contacts of deccan basalts which date to approximately 65 ma bole beds preserved between two successive lava flows can be studied relative to soils developed into the same basalts during the holocene the bole beds have slightly lower ph but significantly lower electrical conductivity values and organic matter contents compared to modern soils they also have higher sio 2 and lower al 2 o 3 and h 2 o crystal lattice water content than modern soils results indicate that the bole beds may not have been subjected to intense weathering and long term pedogenesis but nonetheless formed under uniform rainfall with surface runoff exceeding evaporation weathering chemistry suggests different types of protolith for red and green boles the high stratigraphic frequency of bole beds throughout the deccan volcanics makes them an important source of information about the frequency and environment of inter eruption intervals