a different perspective on glauconite as a chronometer for geologic time scale studies there are advocates of the use of glauconite as a chronometer for geologic time scale studies who insist that if the geohistory of the sample in question is known in detail one can ascertain before hand that the sample will yield a radiometric result that is accurate in the geological sense examples are presented indicating that while some glauconite samples may yield the correct age within their assigned analytical uncertainties when compared to high temperature minerals others clearly do not and are too young by varying degrees the outright acceptance of published results on glauconite can result in erroneous age estimates of various biostratigraphic levels and stage or epoch boundaries

distribution of calcareous dinoflagellates from the maastrichtian to early miocene of dsdp site 357 rio grande rise western south atlantic ocean the evolution of calcareous dinoflagellate communities has been investigated for the latest cretaceous to earliest neogene interval of the mid latitude south atlantic in doing so the response of calcareous dinoflagellates to cenozoic climatic change has been addressed for the first time trends in species composition and distribution patterns of wall types indicate significant changes which correlate with major palaeoenvironmental modifications a first major shift concerning the relative abundance of species and wall types occurred across the cretaceous tertiary boundary the associations remained stable during the entire paleocene and eocene only in the late eocene did a dramatic decrease in temperature cause a slight diversification a second major shift in the abundance patterns occurred across the eocene oligocene boundary the early miocene warming is possibly reflected in the distinct increase in relative abundance of one species the assemblages of calcareous dinoflagellates evidently react to major climatic changes during the cenozoic these poorly investigated organisms may thus provide an important contribution to the understanding of earth s palaeoclimatic evolution

the late maastrichtian nannofossil record of climate change in the south atlantic dsdp hole 525a abstract the phytoplankton response calcareous nannofossils to the late maastrichtian climate evolution is investigated in the south atlantic dsdp hole 525a and compared to published geochemical and micropaleontological data the results point to a succession of dramatic climatic fluctuations cool water indicators ahmuellerella octoradiata kamptnerius magnificus and nephrolithus frequens suggest cool surface water conditions prevailed during chron c30n at the top of c30n their sudden drop in abundance the last occurrence of b constans and the concomitant increase in the tropical species micula murus suggest warming and lower surface water productivity an m murus acme within chron c29r reflects maximum warming during the last 100 kyr of the maastrichtian the decrease in m murus and increase in cool water indicators reflect rapid cooling with the cool climate persisting over the calcareous nannoplankton response to climate change correlate with similar findings in the equatorial atlantic hole 1258a and parallels the stable isotope record of planktic and benthic foraminifera of dsdp hole 525a as well as the decline in 187os 188os comparison of this marine record and the continental climate record in north america suggests a link between deccan volcanism and the late maastrichtian warm event

dinoflagellate cysts sea level changes and planktonic foraminifers across the cretaceous tertiary boundary at el haria northwest tunisia abstract dinoflagellate cysts and planktonic foraminifers have been studied from the cretaceous tertiary k t boundary interval at el haria northwest tunisia a high resolution integrated biostratigraphy is presented the k t boundary is drawn at the level of extinction of cretaceous planktonic foraminifers and is coincident with the first occurrence of the dinoflagellate cyst species danea californica the final extinction of planktonic foraminifers is foreshadowed by a reduction in their total abundance some 5 kyr earlier at the base of the boundary clay this reduction is coeval with reported anomalies in siderophyle elements and 13 c values in the same area dinoflagellate cysts do not show accelerated rates of extinction at k t time associations of dinoflagellate cysts however change drastically and parallel changes in relative numbers of sporomorphs spores and pollen and in the quantity of land derived organic matter jointly these changes reflect a rapidly falling sea level during the final 17 kyr of the mesozoic which culminates at the level of the k t boundary this steep sea level fall at k t time represents a peak regressive pulse at the end of the well documented latest cretaceous regressive trend this short term sea level fall might show to be a wide spread phenomenon which could have caused an excess shrinking of the already reduced areal extent of marginal seas since deep waters in cretaceous oceans were primarily produced in shallow marginal seas the rate of formation of deep water might have been minimized at k t time minimum rates of formation of deep water might have curtailed the slow upward mixing of relatively cool and nutrient rich deeper water through which the thermocline weakened and surficial waters became depleted in nutrients consequently phytoplankton productivity rapidly diminished which in combination with a weakened thermal gradient pushed the highly depth stratified cretaceous planktonic foraminiferal fauna to extinction over a period of time of some 5 kyr guembelitria cretacea was the sole planktonic foraminifer which could accommodate to the low productivity conditions the oscillating rise in sea level at the beginning of the cenozoic reinforced the upward mixing of relatively cool and nutrient rich deeper water steepened the thermocline and replenished the photic layer with nutrients concomitant niche differentiation in the photic layer progressively stimulated morphological innovation amongst early cenozoic planktonic foraminifers the final return of normally sized planktonic foraminifers and of stable and well balanced dinoflagellate cyst associations at about 125 kyr after the k t boundary seems to indicate that primary productivity and niche differentiation in the photic layer begin to revert to optimum levels the earliest cenozoic planktonic foraminiferal species globoconusa minutula and parvularugoglobigerina fringa are thought to have developed from a benthic foraminiferal species rather than having a planktonic ancestry

transmission of wave energy through an offshore wind turbine farm abstract the transmission of wave energy passing an offshore wind farm is studied three effects that can change the wave field are analysed which is the a energy dissipation due to drag resistance b wave reflection diffraction from structures and c the effect of a modified wind field inside and on the lee side of the wind farm the drag dissipation a is quantified by a quadratic resistance law the effect of b is parameterised based on 1st order potential theory a method to find the amount of reflected and transmitted wave energy is developed based on the panel method wamit and a radiation condition at infinity from airborne and satellite sar synthetic aperture radar a model has been derived for the change of the water surface friction c inside and on the lee side of the offshore wind farm the effects have been implemented in a spectral wind wave model mike21 sw and a parametric study to compare the 3 different processes has been carried out the method to study reflection diffraction can be used for any type of offshore structure vessel or a number of structures as long as the assumptions for the use of potential wave theory are valid and the effect of the modified wind field on the water surface friction is known

calcareous nannofossil response to late cretaceous climate change in the eastern tethys zagros basin iran abstract coniacian to maastrichtian changes in calcareous nannofossil assemblages have been investigated in the eastern tethyan shahneshin section central zagros basin iran the nannofossil assemblages are mainly composed of watznaueria spp avg 54 retecapsa spp avg 7 9 cribrosphaerella ehrenbergii avg 7 7 and micula spp avg 5 7 throughout the late campanian there is a trend to lower abundances in watznaueria spp together with increasing abundances of c ehrenbergii and arkhangelskiella cymbiformis which are considered in this basin as the main cool water taxa our results reveal that despite a diagenetic impact on calcareous nannoflora a number of primary paleoecological trends are preserved which depict well features of the progressive late cretaceous cooling the first pronounced cooling episode occurs across the late campanian to early maastrichtian the onset of pronounced cooling in the eastern tethys appears to occur prior to the campanian maastrichtian boundary event cmbe 13c negative excursion in contrast with the boreal realm where pronounced cooling only occurs in the early maastrichtian postdating the onset of the cmbe the coincidence of this earlier cooling in the zagros basin with an interval characterized by a significant increase in benthic foraminifera suggests an amplified response of the assemblage due to a change to shallower environments hence the late campanian calcareous nannofossil assemblage turnover in central zagros is either a response to an early cooling trend in the eastern tethys or to sea level fall or both the mid maastrichtian warming and late maastrichtian cooling episodes are also delineated in the nannofossil assemblage of shahneshin and likely correlate with similar episodes in the boreal realm

strontium isotope stratigraphy for the late cretaceous a new curve based on the english chalk marine 87sr 86sr decreases from 0 70775 in the cenomanian to 0 70730 in the middle turonian before increasing in a near linear manner to 0 70775 in the early maastrichtian this variation has been defined using samples from the english chalk that are closely integrated with the macrofossil and microfossil biostratigraphy of northwestern europe with this new isotope curve a stratigraphic resolution is attainable in correlation that is typically 0 8 ma for the santonian and campanian stages isotopic and biostratigraphic correlations between dorset and norfolk in the uk agree within the limit of analytical error in 87sr 86sr authors

latitudinal migration of calcareous nannofossil micula murus in the maastrichtian implications for global climate change micula murus is one of the main calcareous nannofossil biostratigrapic markers of tethyan and intermediate provinces in the upper maastrichtian uppermost cretaceous a review of its first occurrence at 14 deep sea sites and sections shows that it is time transgressive from the tropical realm of the atlantic and pacific oceans to the intermediate latitudes of the north atlantic south atlantic indian ocean and the northern tethys m murus remained confined to the tropical realm for 1 2 m y in the early late maastrichtian thus supporting high latitudinal thermal gradients it subsequently spread out in the late maastrichtian to temperate latitudes and to the tethys in coincidence with the onset of a thermohaline circulation change at 67 5 ma suggesting a major change in surface water circulation and interocean communications

strontium isotope correlation of the basal maastrichtian stage in antarctica to the european and us biostratigraphic schemes new 87 sr 86 sr dating allows the correlation of a marker horizon within the prolific late cretaceous gunnarites antarcticus faunal assemblage of the cape lamb member snow hill island formation vega island antarctica with reference sections in europe and the usa this horizon is between 81 5 and 96 5 m above the base of the g antarcticus assemblage replicate analysis of six macrofossils from within it yielded a mean value for 87 sr 86 sr of 0 707 735 9 0 000 004 3 2 s e n 17 this ratio in turn yields a numerical age of 71 0 0 2 ma when compared to the standard 87 sr s6 sr reference curve for the latest cretaceous for which the campanian maastrichtian boundary is placed at 71 3 0 5 ma the value of 0 707 735 9 0 000 004 3 correlates to a level in the belemnella lanceolata belemnite zone of the chalk of northwestern germany that is 2 5 5 m beneath the base of the overlying b pseudobtusa zone and 7 5 m above the campanian maastrichtian belemnite boundary and to an interval within the ammonite zonation of the us western interior that spans the early maastrichtian baculites baculus and b eliasi zones but with a most likely level within the b eliasi zone an earliest maastrichtian age is thereby determined for the antarctic horizon and indeed for the entire g antarcticus assemblage gunnarites sensu lato is an important ammonite marker for the base of the maastrichtian throughout the southern high latitude regions and the associated large heteromorph ammonite diplomoceras may comprise a macrofossil link back to the maastrichtian type sections

the end cretaceous in the southwestern tethys elles tunisia orbital calibration of paleoenvironmental events before the mass extinction an integrated study of magnetic mass susceptibility ms bulk stable isotopes and calcareous nannofossil paleoecological changes is undertaken on the late maastrichtian of the elles section tunisia spanning the last ca 1 myr of the cretaceous a cyclostratigraphic analysis reveals the presence of milankovitch frequencies and is used for proposal of two distinct orbital age models and to provide ages of important stratigraphic horizons relative to the age of the cretaceous paleogene boundary k pgb principal component analysis pca performed on the nannofossil assemblage reveal two main factors pca1 mostly representing fluctuations of d rotatorius p stoveri lithraphidites spp retecapsa spp staurolithites spp micula spp and pca2 mostly representing fluctuations of a regularis c ehrenbergii micula spp rhagodiscus spp w barnesiae and zeugrhabdotus spp variations in pca1 and pca2 match changes in bulk 13c and 18o respectively and suggest changes in surface water fertility and temperatures and associated stress the variations in abundances of high latitude taxa and the warm water species micula murus and in bulk 18o delineate fast changes in sea surface paleotemperatures as in many other sites an end maastrichtian greenhouse warming is highlighted followed by a short cooling and an additional warm pulse in the last 30 kyr of the maastrichtian which has rarely been documented so far orbital tuning of the delineated climatic events is proposed following the two different age models calcareous nannofossil assemblages highlight a decrease in surface water nutriency but their species richness remains high through the latest maastrichtian indicating in tunisia a weak impact of deccan volcanism on calcareous nannoplankton diversity before the mass extinction

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

strontium isotope and sequence stratigraphy of the miocene kirkwood formation southern new jersey we use sr isotope stratigraphy to correlate the miocene kirkwood formation of the new jersey coastal plain to the geomagnetic polarity time scale gpts and to ascertain the age of miocene depositional sequences sr isotope stratigraphy confirms diatom biostratigraphy which delineates three kirkwood sequences corresponding to east coast diatom zone ecdz 1 ecdz 2 and ecdz 6 of andrews 1988 sr isotope age estimates of the lowermost sequence ecdz 1 range from 19 2 to 22 6 ma 0 5 m y the middle sequence ecdz 2 ranges from 15 5 to 17 4 ma 0 5 m y a disconformity within ecdz 2 at the belleplain state forest borehole and the wildwood 198a well separates it into two sequences with a possible hiatus from 17 to 16 ma sr isotope age estimates of the upper kirkwood sequence ecdz 6 are not as certain and range from 11 5 to 13 6 ma 0 8 ma a shorter age range of 12 2 13 6 ma for this sequence is supported by its assignment to the d stauracanthus silicoflagellate subzone sedimentation rates were as high as 40 m per million years during deposition of the kirkwood formation suggesting possible tectonic influences on depositional history the timing of lower to middle miocene sequence boundaries from the new jersey coastal plain compares well with other indicators of sea level change including oxygen isotopes miller and others 1991b the global sea level record of haq and others 1987 and the offshore new jersey sequence boundaries of greenlee and others 1992 thus both tectonic and eustatic changes influenced miocene depositional history of the new jersey coastal plain

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

campanian carbon isotope calibrated paleofertility estimates from northwestern tunisia inferences from calcareous nannofossils abstract the 13c calibrated campanian upper part of cc17 uc13 to cc23a uc16 zones calcareous nannofossil assemblages were analyzed to reconstruct paleofertility paleoenvironment and sea level changes from the jebil section north western tunisia seven globally recognized 13c events are noted three positive santonian campanian boundary event scbe early campanian event ece mid campanian event mcae and four negative excursions pillula event conica event late campanian event lce epsilon event or the c1 event the nannofossil assemblage is dominated by watznaueria barnesae 28 lucianorhabdus cayeuxii 8 micula decussata 6 cyclagelosphaera reinhardtii 5 and micula concava 4 in spite of the dominance of w barnesiae range 33 46 5 the signal given by the nannofossil assemblage is primary all species based proxies the percentage abundances of stressed opportunistic taxa high and low fertility taxa cool and warm watermass taxa and nannoconus spp along with the inferred paleotemperature index suggests a cooling trend for the campanian data suggests that oligotrophy was a greater influencing factor than paleotemperature for the observed changes within the nannofossil assemblage as a result of this extreme oligotrophy a distinct assemblage is recorded that is marked by the absence of biscutum reduced abundances of prediscosphaera 0 7 retecapsa 2 3 and zeugrhabdotus 1 8 but with the dominance of w barnesiae

rapid change in strontium isotopic composition of sea water before the cretaceous tertiary boundary a critical aspect of the debate over the origin of the chemical biological and climatological perturbations that characterize the cretaceous tertiary boundary k t boundary is the timescale and detailed pattern of the extinctions and geochemical changes whether the development of the anomalies was catastrophic over tens to hundreds of years or more gradual 103 to 106 years whether the anomalies occur exactly at the boundary or precede it and whether the chemical and biological signatures represent one event or can be resolved into several discrete events are issues fundamental to identifying the cause of the marked changes to determine the timing and rate of change of strontium isotope evolution of sea water during the five million years preceding the k t boundary we analysed foraminifera from an exceptionally thick palaeontologically well characterized marine k t section exposed at bidart southwest france we found a rapid increase in 87sr 86sr of ocean water 1 5 to 2 3 myr before the boundary the increase may be explained by a 10 increase in continental strontium flux to the oceans over a period of about 1 myr

cretaceous to eocene sea level fluctuations on the new jersey margin abstract the new jersey margin contains an extensive record of cretaceous to eocene sea level fluctuations these events have been documented on the basis of sedimentology benthic foraminiferal paleobathymetry paleoslope biostratigraphic recognition of unconformities and their associated hiatuses and on seismic reflection records the record of sea level change for the new jersey margin shows a long term second order rise beginning in the upper albian that is punctuated by numerous third order cycles of change in the upper cretaceous paleocene and eocene the sequences deposited during these cycles that are most readily recognizable are separated by type 1 unconformities sequences bracketed by one or two type 2 unconformities are more difficult to resolve although many have been identified sequences shown on the cycle chart of haq et al 1987 of less than 1 ma duration are the most difficult to recognize and many have not been identified in the new jersey section benthic foraminiferal paleoslope studies indicate that relative sea level rise on the new jersey margin varied on the order of 10 120 m above present sea level much of the preserved record in the coastal plain consists of sediments deposited during rising sea level this has led to a stacked record of sea level rise events separated by unconformities

paleoceanography of the cretaceous tertiary boundary event inferences from stable isotopic and other data we report the results of new stable oxygen and carbon isotope analyses on carbonate fine fraction whole rock and benthic foraminifers caco3 and coarse fraction percentage determinations and trace element sr analyses on carbonate constituents across the cretaceous tertiary k t boundary in deep sea drilling project dsdp sites 47 2 356 384 and 577 and compare them with published results from k t boundary sections in other dsdp sites we used the trace element data and scanning electron microscope examination to evaluate possible diagenetic alteration and relative preservation of the samples analyzed in this study the 18o data when interpreted as isotopic paleotemperatures indicate relative stable surface water and deepwater temperatures in the late maestrichtian followed by somewhat fluctuating temperatures in the early paleocene however there is no indication of either a significant warming or cooling at or following the k t boundary several sites do exhibit somewhat heavier 18o values by about 0 5 across the boundary which might suggest a 2 3 c cooling at most however we interpret these somewhat heavier 18o values as reflecting slightly better preservation of 18o of carbonate constitutents in relatively clay rich intervals e g lower diagentic potential characteristic of the k t boundary the 13c values of carbonate fine fraction and planktonic foraminifers indicate a major negative excursion in surface water total dissolved carbon across the boundary the surface water and deepwater 13c values from benthic foraminifers combined with calculated decreases in carbonate accumulation rates at all sites in the earliest paleocene are consistent with a major decrease in productivity across the k t boundary the decrease in caco3 accumulation rates is due not to increased rates of dissolution but to decreased production in surface waters the low productivity episode lasted at least 1 m y beyond the k t boundary crisis suggesting that hypothesized catastrophic events alone such as impact of an apollo object are not the only explanation for the observed long term decrease in productivity there is also an indication in the 13c curves from several sites that the surface water 13c decrease began in the latest maestrichtian suggesting that the decrease in productivity may have been independent of a hypothesized impact event

the cretaceous paleogene transition at galanderud northern alborz iran a multidisciplinary approach abstract we investigated the cretaceous paleogene k pg transition at the galanderud section northern alborz iran to identify the pattern of mass extinction of planktic foraminifera and to unravel the associated paleoenvironmental changes in a little studied area of the eastern tethys we applied a high resolution quantitative and multidisciplinary study based upon benthic and planktic foraminiferal assemblages clay mineralogy rock magnetic properties stable isotopes and geochemistry in this section the k pg boundary is marked by an abrupt change in lithology from marl to a clay boundary layer a marked decrease in magnetic susceptibility a negative 2 2 13c excursion and a peak in iridium in the uppermost maastrichtian foraminifera are well preserved and diversified suggesting a stable mesotrophic environment by contrast the k pg boundary and basal danian is marked by high values of epifaunal benthic morphogroups low planktic diversity and high percentages of opportunistic species guembelitria cretacea and cervisiella operculata suggesting highly stressed and variable conditions partly due to the dramatic collapse of calcareous primary producers benthic foraminiferal assemblages indicate outer neritic uppermost bathyal depths with slight bathymetric variations the most peculiar and unique aspect of the galanderud section is the occurrence of the three thin chalk layers interbedded within clays above the k pg boundary each marked by positive shifts in 13c and 18o values and consisting of 80 carbonate we propose that the chalk clay deposits in the basal danian reflect changes in seawater chemistry and dynamic changes in circulation upwelling alternating with episodes of enhanced weathering and runoff this section on the northern margin of eastern tethys provides new clues about the pattern of the k pg mass extinction and the paleoenvironmental changes occurring during the biotic recovery phase

benthic foraminiferal ecomarker species of the terminal cretaceous late maastrichtian deep sea tethys abstract benthic foraminiferal distribution patterns throughout the late maastrichtian tethyan deep sea are analyzed many species are ubiquitously distributed throughout this region and therefore it is hard to assess their ecological preferences however five species show distribution patterns which suggest that they may have distinctive paleoenvironmental preferences these preferences are interpreted from hypothesized surface circulation and upwelling patterns additional information comes from recent benthic foraminiferal ecology and from responses to the cretaceous paleogene k pg boundary event this enables us to assess the ecological preferences of these late maastrichtian taxa and establish them as ecological marker ecomarker species for paleoenvironmental interpretation of the late maastrichtian bathyal abyssal tethyan realm 1 eouvigerina subsculptura is suggested to be indicative of reasonably oxygenated upper middle bathyal environments though with high abundance of utilizable organic matter 2 sliteria varsoviensis is linked to areas of late maastrichtian upwelling and seems to have been an epibenthic species with an opportunistic life mode 3 gavelinella beccariiformis and 4 nuttallides truempyi are considered to be indicative of oligotrophic conditions unless they occur with a large proportion of endobenthic morphotypes 5 gavelinella pertusa is proposed to indicate neritic middle bathyal environments of the boreal realm which might be influenced by more seasonal food fluxes and by higher oxygen levels than similar settings in the sub tropics finally the anomalous high abundances of the buliminid species sitella cf plana in deep open ocean environments is discussed in terms of possible mechanisms permitting such a morphologically opportunistic species to thrive in such an assumedly oligotrophic environment

a ten year data set for fetch and depth limited wave growth abstract this paper presents the key results from a ten year data set for lake ijssel and lake sloten in the netherlands containing information on wind storm surges and waves supplemented with swan 40 51 wave model results the wind speeds u 10 effective fetches x and water depths d for the data set ranged from 0 24 m s 1 0 8 25 km and 1 2 6 m respectively for locations with non sloping bottoms the range in non dimensional fetch x g x u 10 2 was about 25 80 000 while the range in dimensionless depth d g d u 10 2 was about 0 03 1 7 land water wind speed differences were much smaller than the roughness differences would suggest part of this seems due to thermal stability effects which even play a role during near gale force winds for storm surges a spectral response analysis showed that lake ijssel has several resonant peaks at time scales of order 1 h as for the waves wave steepnesses and dimensionless wave heights h g h m0 u 10 2 agreed reasonably well with parametric growth curves although there is no single curve to which the present data fit best for all cases for strongly depth limited waves the extreme values of d 0 03 and h m0 d 0 44 at the 1 7 m deep lake sloten were very close to the extremes found in lake george australia for the 5 m deep lake ijssel values of h m0 d were higher than the depth limited asymptotes of parametric wave growth curves the wave model test cases of this study demonstrated that swan underestimates h m0 for depth limited waves and that spectral details enhanced peak secondary humps were not well reproduced from h m0 d 0 2 0 3 on swan also underestimated the quick wave response within 0 3 1 h to sudden wind increases for the remaining cases the new van der westhuysen a j zijlema m and battjes j a 2007 nonlinear saturation based whitecapping dissipation in swan for deep and shallow water coast eng 54 151 170 swan physics yielded better results than the standard physics of komen g j hasselmann s hasselmann k 1984 on the existence of a fully developed wind sea spectrum j phys oceanogr 14 1271 1285 except for persistent overestimations that were found for short fetches the present data set contains many interesting cases for detailed model validation and for further studies into the evolution of wind waves in shallow lakes

calcareous nannofossil extinction and survivorship across the cretaceous paleogene boundary at walvis ridge odp hole 1262c south atlantic ocean abstract site 1262 in the south atlantic ocean has provided a stratigraphically continuous deep cretaceous paleogene boundary sequence high resolution calcareous nannofossil quantitative analyses were carried out across the k p boundary and provided a remarkable record of the abrupt and catastrophic extinction the calcareous nannofossil assemblages are abundant and well preserved allowing to obtain a precise bioevent sequence and to document in detail the survivors and victims and the subsequent recovery across the k p boundary late maastrichtian diversity and absolute abundance is high and no decrease towards the boundary has been observed the relative abundance of cretaceous species does not suffer important changes during the latest maastrichtian however the increase in abundance of cool water taxa paralleled with a decrease of warm water taxa in the uppermost 2 cm of the maastrichtian revealed a pulse of surface water cooling the k p boundary is marked by an important decrease in calcareous nannofossil absolute abundance the increase of cretaceous persistent species such as cyclagelosphaera reinhardtii together with the dinoflagellate cysts of thoracosphaera operculata and the appearance of the new paleocene taxa cyclagelosphaera alta and biantholithus sparsus these events are followed by the successive relative abundance increases of other cretaceous survivors as zeugrhabdotus sigmoides markalius inversus and biscutum recognized as r selected taxa adapted to eutrophic and cold water environments in the early danian several first occurrences of small new paleocene species have been observed calcareous nannoplankton evolutionary attempts to colonize vacant niches left by the extinct cretaceous species only some forms succeed and become ancestors to the cenozoic assemblages the other disappear in few kiloyear the presence of a reworking mixing interval above the k p boundary hampered to unequivocally interpret if the few cretaceous vanishing taxa may have survived for a very short time after the k p extinction

biostratigraphic subdivision and correlation of upper maastrichtian sediments from the atlantic coastal plain and blake nose western atlantic

the middle cenomanian event in the equatorial atlantic the calcareous nannofossil and benthic foraminiferal response abstract in addition to oceanic anoxic event 2 oae2 other perturbations of the carbon cycle occurred during the cenomanian and turonian of which the middle cenomanian event mce is the most prominent one in palaeoecological publications however this event is strongly underrepresented in contrast to the well studied oae2 in order to fill this gap we have studied early cenomanian to late turonian calcareous nannofossil and benthic foraminiferal assemblages of ocean drilling program site 1260 at demerara rise western equatorial north atlantic in order to decipher biotic changes throughout this interval and especially across the mce our data show distinctive changes in the relative abundance of certain calcareous nannofossil taxa and a drastic decrease in benthic foraminiferal diversities and abundances associated with the mce in the lower part of the studied section and prior to the mce a mixed water column with high nutrient availability in the upper photic zone is suggested based on very high relative abundances of the mesotrophic eutrophic nannofossil species biscutum constans around the mce interval certain nannofossil taxa e g rhagodiscus asper show a distinctive decrease in relative abundance while others become more dominant taxa which increase in relative abundance after the mce e g eprolithus floralis are interpreted as either having favoured less eutrophic surface waters or having inhabited deeper parts of the photic zone in a well stratified water column this interpretation is supported by published oxygen isotope and tex86 data which suggest increased water column stratification starting with the mce and lasting to the end of the cenomanian stage as a result of the implementation of a saline intermediate to deep water mass during this interval our study shows that the mce was a significant biotic event in the cenomanian turonian equatorial atlantic characterised by a lasting change of surface and bottom water ecosystems

strontium isotope stratigraphy in the late cretaceous numerical calibration of the sr isotope curve and intercontinental correlation for the campanian the white chalk exposed in quarries at lagerdorf and kronsmoor northwestern germany provides a standard section for the european upper cretaceous the sr 87 sr 86 values of nannofossil chalk and belemnite calcite increase upward through 330 m of section from less than or equal to 0 70746 in the upper santonian to greater than or equal to 0 70777 in the lower maastrichtian the data define three linear trends separated by major points of inflection at stratigraphic heights in the section of 162 m 75 5 ma in the upper campanian galerites vulgaris zone and at 6 m 82 9 ma just above the base of the campanian in the inoceramus lingua goniateuthis quadrata zone the temporal rate of change of sr 87 sr 86 was constant through each of the linear segments of our isotope curve when viewed at the resolution of our average sampling interval 0 15 m y fine structure if rear may record brief 100 kyr excursions of srsr sr 87 sr 86 from values expected from the overall trends in lagerdorf the boundary between the santonian and campanian stages taken here as the level of first occurrence of the belemnite gonioteuthis granulataquadrata has an sr 87 sr 86 of 0 707473 5 this is within error of the values of 0 707457 16 for this boundary in the u s western interior base of the scaphites leei iii zone and 0 707479 9 for this boundary in the english chalk top of the marsupites testudinarius zone in kronsmoor the boundary between the campanian and maastrichtian stages taken here as the level of first occurrence of the belemnite belemnella lanceolata has an sr 87 sr 86 of 0 707723 4 this is within error of the values of 0 707725 20 for this boundary in the u s western interior base of the baculites eliasi zone and 0 707728 5 for this boundary in the english chalk defined as in germany

the cretaceous tertiary boundary event in the north pacific planktonic foraminiferal results from deep sea drilling project site 577 shatsky rise a detailed micropaleontologic analysis of sediments from deep sea drilling project site 577 from the shatsky rise north pacific was undertaken to describe extinction and radiation patterns of plank tonic foraminifera in a continuous carbonate sequence spanning the cretaceous tertiary k t boundary a 15 m section containing the boundary was closely sampled and contained planktonic foraminiferal assemblages characteristic of the late maastrichtian abathomphalus mayaroensis zone through the danian globorotalia uncinata zone the cretaceous tertiary boundary was placed at the abrupt disappearance of almost all maastrichtian planktonic foraminifera coincident with these extinctions was the presence of a large number of microtektitelike spherules the most important faunal change in the late maastrichtian was an abrupt increase in the relative abundance of the high latitude species hedbergella monmouthensis together with the appearance of diminutive populations of guembelitria cretacea and globigerina eugubina approximately 20 000 years before the boundary these changes are interpreted as indicating a cooling of surface water conditions globigerina eugubina and g cretacea were the only planktonic foraminiferal species to survive the cretaceous tertiary boundary event at this locality the o 18 and c 13 values of g eugubina from below the k t boundary are nearly the same as those from above the boundary but in both cases the o 18 values indicate relatively cooler paleotemperatures than those from other coexisting planktonic foraminiferal species in addition the c 13 values of g eugubina are lighter than those of the other planktonic foraminifera such a relationship might suggest that g eugubina lived in cooler shallow intermediate water masses advected from higher latitudes during a latest maastrichtian cooling episode better preservation of planktonic foraminifera a progressive change in the c 13 of benthic foraminifera and a brief positive excursion in c 13 of the carbonate fine fraction and of planktonic foraminifera within 20 to 30 cm below the k t boundary all suggest important paleoceanographic changes that preceded the extinction event a large population of aberrant g eugubina and eoglobigerina was observed in the earliest danian these forms are characterized by the development of secondary apertures bullae and abnormal final chambers these abnormal morphotypes are considered to be ecophenotypic variants reflecting ecologic stress or instability in the earliest cenozoic marine environment

dinoflagellate cysts from the upper campanian upper cretaceous of hornby island british columbia canada with implications for nanaimo group biostratigraphy and paleoenvironmental reconstructions abstract thirty mudstone samples from coastal exposures of the northumberland formation on hornby island british columbia canada yielded diverse dinoflagellate cyst and terrestrial sporomorph assemblages a late campanian age for the formation has been well defined through magnetostratigraphy macrofossil biostratigraphy and geochemical studies of the hornby island section dinoflagellate cyst taxa corresponding to 61 genera are exceptionally well preserved and include specimens referable to at least 68 formally established species the earliest occurrences of canninginopsis maastrichtiensis druggidium cf discretum phanerodinium belgicum renidinium cf vitilaire senegalinium simplex spiniferella cornuta and xenicodinium delicatum sensu slimani et al are reported along with the most recent occurrence of senoniasphaera protrusa extending their stratigraphic ranges into the upper campanian the palynomorph assemblages support a late campanian age two dinoflagellate cyst ecozones are recognized ecozone 1 and ecozone 2 assemblages suggest sediment deposition in an inner shelf environment with moderate to high nutrient input and primary productivity

the manumiella seelandica global spike cooling during regression at the close of the maastrichtian abstract manumiella seelandica lange 1969 bujak and davies 1983 emend firth 1987 occurs in great abundance together with a closely related and possibly conspecific form isabelidinium sp virtually at the end of the maastrichtian the abundance of m seelandica immediately adjacent the cretaceous paleogene kpg boundary and its global distribution serve as an excellent biostratigraphic marker for dating it the abundance spike is widely distributed in both northern and southern hemispheres and ranges from locations as far south as seymour island antarctica to as far north as west greenland the global distribution of the m seelandica spike in such widely separated areas and the ease with which it is recognized in closely sampled sections underscores its value in dating until recently this short lived event was correlated within an interval of global sea level fall and regression which extended from the latest maastrichtian into the earliest danian that is that the species became numerically abundant as the shoreline approached however based on our study of the boundary interval at bass river in southern new jersey usa we propose that an additional factor may have contributed to its origin our investigation of this section shows that there is a prominent abundance spike in the 20 cm 7 8 in interval immediately beneath the boundary and that this interval correlates precisely with the 18o isotope evidence of cooling at bass river the last 500 ky of the maastrichtian was a period of global warmth as revealed by geochemical evidence however based on the geochemical evidence a mild cooling period began within tens of thousands of years of the close of the cretaceous period based on this correlation we present the hypothesis that the cooling event played an important role in producing this global assemblage of dinoflagellates study of a large number of fossils in the sample situated 15 cm 5 85 in beneath the boundary shows that there is considerable variation in overall form and archeopyle excystment in manumiella seelandica the same degree of variation was not observed in the samples with fewer specimens

eustasy versus subsidence lower paleocene depositional sequences from southern alabama eastern gulf coastal plain four distinct sequences of rise and fall in relative sea level may be inferred from the lower paleocene strata in southern alabama southern alabama is part of the eastern gulf coastal plain a passive continental margin these third order sequences are traceable from the western part of the study area where a thick section of deltaic influenced siliciclastic sediments was deposited in a subsiding salt withdrawal basin to the eastern part of the study area where a somewhat thinner sequence of carbonate and siliciclastic deposits accumulated on a stable platform formed over paleozoic basement rocks the fact that these sequences and their component systems tracts can be recognized and traced throughout southern alabama considering the significant differences in subsidence and sedimentation rates from the western part to the eastern part of the study area indicates that some factor other than subsidence rates or sediment supply controls the cyclicity exhibited by these sequences eustasy is interpreted as that controlling factor this interpretation is consistent with the observations of previous writers that the conditions of differential subsidence climate and sediment supply may overprint the effects of global sea level change but that these factors usually do not mask the impacts of eustasy

strontium isotope profiles across k t boundary sequences in denmark and antarctica strontium isotope profiles derived from minimally altered samples across marine k t boundary sequences exposed at kjolby gaard and nye klov denmark and on seymour island antarctica show neither the boundary excursions nor the boundary spikes in 87sr 86sr that have been reported for k t boundary sequences from elsewhere nor do our data conform to modelled predictions of the sr isotopic response of the oceans to a positive spike in 87sr 86sr at the terminal cretaceous boundary values for 87sr 86sr with 95 confidence intervals are 0 707828 3 in denmark and 0 707832 7 in antarctica our data suggest that 87sr 86sr stopped increasing and started decreasing at least 90 ka before the k t boundary

late maastrichtian warming in the boreal realm calcareous nannofossil evidence from denmark abstract the climate of the mid to late cretaceous was probably one of the warmest of the phanerozoic but by the late maastrichtian distinctly cool high latitude regions had developed studies from low latitude sites have demonstrated that the late maastrichtian cooling was punctuated by two pulses of warming but the response of nannoplankton to climatic fluctuation in the mid to high northern latitudes is not well documented a high resolution nannofossil study was undertaken on subsurface chalk sections of denmark which provide a stratigraphically complete record of late maastrichtian sedimentation of nannofossil ooze in an extensive mid to high latitude carbonate province the quantitative nannofossil data from cored sections through the upper maastrichtian chalk reveal subtle but significant shifts in taxa interpreted as having been sensitive to temperature fluctuations arkhangelskiella cymbiformis kamptnerius magnificus lucianorhabdus cayeuxii nephrolithus frequens and watznaueria barnesiae and indicate two late maastrichtian warming events correlatable with those of low latitude records and a decrease in surface water temperatures in the latest maastrichtian

p and s wave travel time inversions for subducting slab under the island arcs of the northwest pacific we have observed slablike high p and s velocity anomalies around the wadati benioff zone under island arcs of the northwest pacific through travel time tomographic inversions nineteen years of international seismological centre travel time residuals for events and stations in this large region are used analyses of resolution and noise show that the images are generally well resolved the images illustrate that slab anomalies are continuous along strike in most parts of the upper mantle of the region and become contorted and generally broadened with depth near the bottom of the upper mantle fingering of the slabs including segmenting and spreading is indicated the fast anomalies associated with the japan izu bonin and mariana subduction zones tend to flatten to subhorizontal at depth while downward spreading may occur under parts of the mariana and kurile arcs the fast anomalies below 700 km are not in the shape of a single coherent sheet the principal compressional axes of focal mechanisms in the region consistently follow the downdip direction of the high velocity slab even when it bends to subhorizontal at depth the depth at which compression begins to dominate the downdip stress regime in the slab apparently depends on bending of the slab and its dip slab fingering and intense deep seismicity probably are the consequence of the slab encountering a barrier of some form around the 670 km discontinuity

late maastrichtian to early danian calcareous nannofossils at elles northwest tunisia a tale of one million years across the k t boundary a detailed study of calcareous nannofossils of the elles section tunisia was extended over an interval of about 1 myr including the k t boundary the late maastrichtian assemblages are rich and well preserved pulses of surface water cooling probably related to episodic upwelling are revealed by the increase in abundance of cool water taxa mainly kamptnerius magnificus nephrolithus frequens gartnerago spp in certain late maastrichtian samples paralleled by a decrease of the warm water species watznaueria barnesae a sensible decrease in abundance of arkhangelskiella cymbiformis and its return to smaller specimens was also recorded at elles probably as the result of surface water productivity changes in the latest maastrichtian some maastrichtian samples at elles contain neobiscutum romeinii and chiasmolithus sp these taxa formerly thought to be tertiary coccoliths are here considered as truly maastrichtian occurrences as at el kef the danian of elles is characterised by successive blooms of surviving and newly evolved species though the abundance of calcareous nannofossils rapidly reached the same level as in the maastrichtian the lower diversity still points to a mesotrophic poorly stratified marine environment the reworking versus survivorship of cretaceous species found in danian samples remains an unresolved question but a hypothesis of survivorship is also strengthened by the presence of several coccospheres of w barnesae and bidiscus rotatorius well above the boundary the effect of the marine environmental change across an expanded k t boundary section as elles appears complex if seen through calcareous nannofossils from a geological point of view the k t boundary floral turnover at elles seems dramatically synchronous with the signatures of an extraterrestrial impact superimposed on long term background environmental and climatic changes however a precise succession of events based on appearance disappearance of nannofossil species across the cretaceous paleocene transition is far from being unanambiguous

paleogene early neogene paleoenvironmental reconstruction based on palynological analysis of odp hole 959a west africa abstract five paleoenvironmental intervals interval 1 interval 5 are established in the late paleogene early neogene of the ocean drilling program odp site 959 hole 959a cote d ivoire ghana transform margin in the eastern equatorial atlantic the intervals are based on dinoflagellate cyst and palynofacies analyses of 30 samples covering a 273 3 m interval we observed an abundance of the filisphaera group filisphaera filifera and bitectatodinium tepikiense which is interpreted as an arctic migration to equatorial regions during a narrow interval in the early oligocene early rupelian in addition we document one hiatus within interval 3 in the early miocene aquitanian the dominance of typically restricted marine species of the polysphaeridium group homotryblium plectilum and polysphaeridium zoharyi at several horizons in the open oceanic sediments of odp hole 959a appear to be very distinctive events upon integrating dinoflagellate cyst data with prior lithologic and microfossil data we interpret these dominance events as being due to offshore transportation by turbidity currents intervals 1 and 2 hiatus event interval 3 or hyperstratification conditions intervals 3 and 4 in addition the dominance of cribroperidinium spp c giuseppei and c tenuitabulatum in the upper part of the section within paleoenvironmental interval 5 is suggestive of cold water masses during a strong upwelling period in the latest early miocene burdigalian the general abundance of amorphous organic matter alongside the dinoflagellate cyst assemblage supports an outer neritic oceanic depositional environment for the studied site the consistent occurrence of degraded phytoclasts in the sediments also suggests fluvial outflows to this offshore site

middle late cretaceous climate of the southern high latitudes stable isotopic evidence for minimal equator to pole thermal gradients a detailed 18 o and 13 c stratigraphy has been generated from analysis of well preserved albian early maastrichtian foraminifera from deep sea drilling project dsdp sites 511 and 327 falkland plateau 58 s 62 s paleolatitude in the southern south atlantic and cenomanian and coniacian santonian foraminifera from dsdp site 258 naturaliste plateau 58 s paleolatitude in the southern indian ocean these results when combined with previously published maastrichtian stable isotope data from ocean drilling program odp site 690 weddell sea 65 s paleolatitude provide new insight into the climatic and oceanographic history of the southern high latitudes during middle late cretaceous time the planktonic foraminifer 18 o curves reveal a gradual warming of surface waters from the albian through the cenomanian followed by extremely warm surface waters from the turonian through the early campanian long term cooling of surface waters began in the late early campanian and continued through the end of the maastrichtian the benthic foraminifer 18 o record generally parallels changes in the oxygen isotopic curves defined by shallow dwelling planktonic foraminifera the vertical oxygen and carbon isotopic gradients were relatively low during the albian cenomanian high from the turonian early campanian and then low during the late campanian and maastrichtian foraminiferal oxygen isotopic data from published sources and this study are averaged for each site corrected for latitudinal changes in salinity based on modern day surface water values and plotted versus paleolatitude for the late albian coniacian santonian and late maastrichtian differences between lowand high latitude surface water paleotemperatures are estimated at 14 c during the late albian and late maastrichtian but the coniacian santonian reconstruction reveals only a 0 4 c latitudinal temperature gradient uncertainty regarding cretaceous salinity gradients and possible diagenetic alteration of 18 o values introduce error into our estimates of paleolatitudinal thermal gradients however apparent low equator to pole temperature differences could indicate much higher poleward heat transport than at present

dinoflagellate biostratigraphy and sequence stratigraphy of the type maastrichtian upper cretaceous enci quarry the netherlands abstract the upper maastrichtian strata in enci quarry contain rich assemblages of marine palynomorphs especially dinoflagellate cysts a quantitative study shows that a marked change from dinoflagellate dominated assemblages to assemblages dominated by the acritarch genus paralecaniella occurs at the base of the lanaye member indicating a change from open marine to marginal marine conditions a sequence stratigraphic breakdown into systems tracts based on an interpretation of the changes in the palynological assemblages and lithology suggests the presence of parts of four sedimentary cycles in the enci section three of the cycles may be correlated with the third order cycles uza 4 5 ta 1 1 and ta 1 2 of haq et al 1988 the fourth cycle is probably of higher order three dinoflagellate cysts are new laciniadinium aquiloniforme schioler et al sp nov leberidocysta verrucosa schioler et al sp nov and pulchrasphaera minuscula schioler et al gen et sp nov the description of rottnestia wetzelii is emended and the new combination cribroperidinium wilsonii slimani schioler et al comb nov is proposed the triblastula utinensis zone isabelidinium cooksoniae zone and the palynodinium grallator zone with its two subzones tanyosphaeridium magdalium subzone and thalassiphora pelagica subzone can be recognized in the enci section

calcareous nannofossils as paleoproductivity indicators in upper cretaceous organic rich sequences in israel abundant and diverse calcareous nannofossil assemblages were found in organic rich carbonate sequences which accumulated in a campanian maastrichtian upwelling belt along the southeastern tethys the sequences studied represent the inner shallower and the outer deeper parts of the upwelling belt the paleoenvironmental significance of selected nannofossil taxa and their utility in productivity reconstruction was established by comparing their distribution to foraminifera and dinocyst based productivity profiles based on the calcareous nannofossil assemblages a high productivity group and a low productivity group of species were determined the distribution of these groups agrees well with the dinocyst and foraminifera based productivity curves and hence can be used to record paleoproductivity changes the ratio between the high productivity and low productivity nannofossil groups the nannofossil index of productivity nip is proposed here as a productivity proxy that can be utilized in reconstructing basinal productivity development a quantitative analysis of the nannofossil assemblages indicates that their abundance and diversity increase towards the open sea in the outer and less productive part of the upwelling belt in the inner and more productive part of the upwelling belt the nannofossils assemblages become less abundant and less diverse relative to those of the open marine environment micula decussata and watznaueria barnesae are common to abundant in most samples m decussata becomes more abundant in poorly preserved samples on the other hand the distribution of w barnesae matches better with intermediate productivity levels

late aptian cretaceous paleoceanography of the south atlantic ocean inferred from dinocyst communities of the sergipe basin brazil the late aptian early cretaceous is a crucial time interval for understanding the paleoceanographic changes in the southern hemisphere oceanographic changes in the emerging south atlantic ocean during this interval are reflected in the stratigraphic distribution of dinoflagellate communities recorded in the muribeca and riachuelo formations of the sergipe basin in northeastern brazil the subtilisphaera community in the lower and middle parts of the section appears to be related to the subtilisphaera ecozone and suggests the onset of tethyan influence in the central south atlantic in a restricted to inner neritic environment the succeeding spiniferites community in the middle part of the section represents the first significant transgression probably of eustatic origin the cyclonephelium exochosphaeridium community in the upper part of the section appears to be related to an oceanic event characterized by intermittent dysoxic anoxic conditions the uppermost part of the section is dominated by the spiniferites community related to a progressive regional transgression and culminating in an open marine fully tethyan environment in the central part of the widening south atlantic

coastline responses to changing storm patterns 1 researchers and coastal managers are pondering how accelerated sea level rise and possibly intensified storms will affect shorelines these issues are most often investigated in a cross shore profile framework fostering the implicit assumption that coastline responses will be approximately uniform in the alongshore direction however experiments with a recently developed numerical model of coastline change on a large spatial domain suggest that the shoreline responses to climate change could be highly variable as storm and wave climates change large scale coastline shapes are likely to shift causing areas of greatly accelerated coastal erosion to alternate with areas of considerable shoreline accretion on complex shaped coastlines including cuspate cape and spit coastlines the alongshore variation in shoreline retreat rates could be an order of magnitude higher than the baseline retreat rate expected from sea level rise alone

late cretaceous to early paleocene climate and sea level fluctuations the tunisian record abstract climate and sea level fluctuations across the cretaceous tertiary k t transition in tunisia were examined based on bulk rock and clay mineralogies biostratigraphy and lithology in five sections el melah el kef elles ain settara and seldja spanning from open marine to shallow inner neritic environments late campanian to early danian trends examined at el kef and elles indicate an increasingly more humid climate associated with sea level fluctuations and increased detrital influx that culminates at the k t transition this long term trend in increasing humidity and runoff in the tethys region is associated with middle and high latitude cooling results of short term changes across the k t transition indicate a sea level lowstand in the latest maastrichtian about 25 100 ka below the k t boundary with the regression marked by increased detrital influx at el kef and elles and a short hiatus at ain settara a rising sea level at the end of the maastrichtian is expressed at elles and el kef by deposition of a foraminiferal packstone a flooding surface and condensed sedimentation mark the k t boundary clay which is rich in terrestrial organic matter the p0 p1a transition is marked by a sea level lowstand corresponding to a short hiatus at ain settara where most of p0 is missing and a period of non deposition and erosion in the lower part of p1a 64 95 ma at seldja p0 and possibly the topmost part of cf1 are missing these sea level fluctuations are associated with maximum humidity these data suggest that in tunisia long term environmental stresses during the last 500 ka before the k t boundary and continuing into the early danian are primarily related to climate and sea level fluctuations within this long term climatic trend the pronounced warm and humid event within the latest maastrichtian zone cf1 may be linked to greenhouse conditions induced by deccan volcanism the absence of any significant clay mineral variations at or near the k t boundary and ir anomaly suggests that the bolide impact had a relatively incidental short term effect on climate in the tethys region

an overview and brief description of common marine organic walled dinoflagellate cyst taxa occurring in surface sediments of the northern hemisphere abstract organic walled resting cysts of planktonic dinoflagellates occur commonly in modern marine sediment where they represent with rare exceptions the only geologically preservable part of the life cycle although many species do not produce fossilizable resting cysts upper quaternary sediments contain a diverse cyst record that is used frequently for paleoenvironmental reconstruction and stratigraphic analysis reconstructions of past sea surface conditions rely on an understanding of the distributions of dinoflagellate cysts in modern sediments linked to their respective environmental parameters underpinned by sound taxonomy and standardized nomenclature stratigraphic studies additionally require knowledge of morphological details to distinguish extant from similar extinct taxa here 51 dinoflagellate cyst species and two informal cyst morphotypes that are commonly encountered during routine palynological analysis of upper quaternary marine sediments from the northern hemisphere are briefly described taxonomically and illustrated in addition their lowest stratigraphic occurrences are provided

the cretaceous paleogene k p boundary at brazos texas sequence stratigraphy depositional events and the chicxulub impact abstract two cores from brazos texas spanning the cretaceous paleogene k p boundary are investigated by a multidisciplinary approach aiming at unraveling environmental changes and sequence stratigraphic setting in addition the sedimentology of the k p event deposit and its correlation with the k p boundary is studied foraminifera and nannofossil stratigraphy indicates that both cores include a latest maastrichtian zone cf1 cf2 and earliest danian p0 p and p1a shale sequence with a sandy and chicxulub ejecta bearing event deposit at the k p boundary a hiatus of unknown duration may be present by the unconformable base of the event deposit planktic foraminifera as well as calcareous nannofossil abundance and diversity both decline abruptly above the event deposit k p mass extinction whereas benthic foraminifera show a pronounced faunal change but no mass extinction mineralogical and geochemical proxies suggest that except for the sandwiched k p event deposit no facies change took place across the k p boundary and no evidence for adverse an or dysoxic sedimentary conditions following the chicxulub impact was observed therefore the interval bracketing the k p event deposit is considered as highstand systems tract increased coarse detritus input and low planktic benthic p b foraminifera ratios during the earliest paleocene p0 and p both suggest an increased coastal proximity or relative sea level lowering although the k p mass extinction of planktic foraminifera might have influenced the p b ratios as well consequently the sandy shales of the early paleocene are considered as late regressive highstand or as lowstand deposit during p1a shales assigned as transgressive systems tract overlie a pyrite and glauconite rich bioturbated transgressive surface or type 2 sequence boundary the smectite dominated clay assemblage with minor illite kaolinite and chlorite indicates semiarid humid climates with no obvious shifts across the k p boundary the magnetic susceptibility signature during the maastrichtian reveals a subtle cyclic or rhythmic pattern whereas a high amplitude cyclic pattern is present during the early danian the k p event deposit shows a succession of high energetic debris flows and turbidites derived from multiple source areas followed by a period of decreasing current energy deposition was likely triggered by multiple tsunami or tempestites followed by a prolonged period of reworking and settling the chicxulub ejecta at the base of the k p event deposit consists of mg rich smectite as well as fe mg rich chlorite spherules their mineralogical composition points to target rocks of mafic to intermediate composition presumably situated in the northwestern sector of the chicxulub impact structure besides these silicic phases the most prominent ejecta components are limestone clasts accretionary carbonate clasts and microspar suggesting that the texas area received ejecta also from shallow carbonate rich lithologies at the impact site on the yucatan carbonate platform the excellent correlation of chicxulub ejecta at brazos with ejecta found in the k p boundary layer worldwide along with the associated mass extinction provides no evidence that chicxulub predated the k p boundary and allows for unequivocal positioning of the k p boundary at the event deposit

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

late cretaceous eocene nannofossil and magnetostratigraphic correlations near gubbio italy abstract using a modified sample preparation technique we have been able to establish a detailed lower campanian to upper eocene nannofossil stratigraphy in the bottaccione and contessa highway sections near gubbio appearance and extinction levels of virtually all the commonly used calcareous nannofossil zonal markers have been recognized and can now be closely correlated with the planktonic foraminifera zonation and the magnetic reversal stratigraphy previously established in these sections comparisons with the nannofossil calibrations of the oceanic magnetic anomaly sequence in deep sea drilling project dsdp sites suggest that magmetic subchrons c17n and c25n are missing in the bottaccione section the observed variability of the relative stratigraphic position of most plankton events is confirmed to less than one magnetic subchron absolute abundance paleobiogeographic restriction and differential preservation render some of the traditionally used biostratigraphic events less reliable than others

bartonian to priabonian dinoflagellate cyst biostratigraphy and paleoenvironments of the m karcha section in the southern tethys margin rif chain northern morocco abstract palynological analyses were performed on the eocene sediments of the m karcha section which is located in the taza region structural tsoul unit eastern external rif northeastern morocco the palynological content of this section is composed essentially of well preserved and diverse dinoflagellate cyst assemblages allowing detailed taxonomic determinations age assignments biostratigraphic correlations and paleoenvironmental interpretations other palynomorphs such as spores pollen grains and foraminiferal linings are rare and therefore not taxonomically determined up to the genus level 131 dinoflagellate cyst species were identified age assignments are based on dinocyst bioevents considered previously as potential biostratigraphic markers of the bartonian and priabonian including the lowest occurrences los of glaphyrocysta semitecta impagidinium dispertitum rhombodinium perforatum cooksonidium capricornum stoveracysta ornata stoveracysta sp 2 of brinkhuis and biffi 1993 and lo and highest occurrence ho of schematophora speciosa the quantitative palynological analyses based mainly on dinoflagellate cysts through the m karcha section revealed an inner neritic generally lagoon environment with a low productivity alternated with short episodes of the open marine influence

calcareous nannofossil biostratigraphy and paleoecology of the cretaceous tertiary transition in the central eastern desert of egypt abstract the gebel qreiya and nearby wadi hamama sections of the central eastern desert are among the most complete k t boundary sequences known from egypt the two sections were analyzed spanning an interval from l 83 myr below to about 3 myr above the k t boundary a 1 cm thick red clay layer at the k t boundary at gebel qreiya contains an ir anomaly of 5 4 ppb the high resolution study and well preserved nannoflora provide good age control and the first quantitative records of calcareous nannofossil assemblages for paleoecological interpretations across the k t transition in egypt four zones micula murus micula prinsii np1 and np2 were distinguished and correlated with other nannofossil and planktonic foraminiferal zonations that are broadly applicable for the eastern tethys region latest maastrichtian assemblages are abundant and diverse though cretaceous species richness progressively decreased across the k t boundary dominant species include arkhangelskiella cymbiformis micula decussata and watznaueria barnesae with high abundance of dissolution resistant m decussata reflecting periods of high environmental stress thoracosphaera blooms mark the k t boundary and are followed by an acme of the opportunistic survivor braarudosphaera bigelowii the first appearance of the new tertiary species cruciplacolithus primus and an acme of coccolithus cavus pelagicus these successive abundance peaks provide the basis for subdivision of the early danian zones np1 and np2 into five subzones correlation of selected nannofossil taxa from the egyptian sections with those from various onshore marine and deep sea sections provides insights into their paleoenvironmental and paleoecological affinities

calcareous nannoplankton proxies for palaeoenvironmental reconstruction of the albian cenomanian succession in north western israel mount carmel region abstract we present data on the calcareous nannofossil distribution in the albian cenomanian borehole ct8 obtained from the carmel area nw israel the nannofloral assemblage consists of 113 species with watznaueria spp dominating the entire succession the detailed calcareous nannofossil biostratigraphy of this section is established and seven nannofossil sub zones are recognised for the first time the age of the tavasim tuff v2 is biostratigraphically identified as late albian the quantitative analysis of the calcareous nannofossils suggests warm open marine or coastal mainly oligotrophic conditions throughout the entire succession of borehole ct8 with evident fluctuations of temperatures and fertility and a general trend towards cooling in the uppermost part of the sequence middle late cenomanian temperature and nutrient variations correspond to those in the western tethys thus suggesting at least a supra regional extent of processes detected in the carmel region the biostratigraphy shows no evidence of hiatuses in the studied section but the absence of positive carbon isotope anomalies associated with the oceanic anoxic event oae 1d and mid cenomanian event elsewhere suggests that the oae 1d is possibly missing in the studied section due to a hiatus around the isfiye fm arqan fm boundary

dinoflagellate species and organic facies evidence of marine transgression and regression in the atlantic coastal plain abstract palynological evidence is used to date and interpret depositional environments of sediments of campanian maestrichtian and early danian ages cored in three wells from south carolina and georgia the evidence is usefil for distinguishing environments which lithofacies evidence indicates a range from nonmarine to coastal to inner neritic shallow shelf numerous dinoflagellate species and an organic facies defined abundant amoprphous debris amorphous debris facies distinguish shallow shelf sediments deposited during marine transgression the nearshore amorphous debris facies of late campanian age consists of heterogenous assemblages dominated by palaeohystrichophora infusorioides deflandre or hystrichosphaerina varians may the farther offshore amorphous debris facies of late early maestrichtian to late maestrichtian age consists of heterogenous assemblages dominated by glaphyrocysta retiintexta cookson and or areoligera medusettiformis wetzel the larger number of dinoflagellate species in the offshore facies represents the maximum transgression detected in the investigated interval a multiple occurrence datum defined by the combination of first appearance klast appearances and sole occurrence of dinoflagellate species at the base of each interval distinguished by the amorphous debris facies provides the first evidence of marine transgression relatively small organic residues consisting of intertinite and few or no palynomorphs define the inertinite facies in nonmarine deltaic and in coastal lagoonal tidal flat interdistributary bary sediments dinocyt s are absent in the nonmarine sediments and are represented by few species and few specimens in the coastal inertinite faceis a third organic facies vascular tissue facies is defined by the abundance of land plant tissue sporomorph species including those of the normapolles pollen group and of pteridophyte spores comprise a large proportion of the total palynomorph flora in the inertinite and vascular tissue facies the vascular tissue facies occurs in the proximal prodelta and nearshore shallow shelf lithofacies of early maestrichtian age baed in the sequence of organuic facies dinoflagellate species abundance and lithofacies in the investigated wells the nonmarine and coastal inertinite facies was first deposited and was followed during the late campanian by a marine trangression when the nearshore amorphous debris facies was deposited this was followed in the early maestrichtian by the influx of terrigenous organic matter vascular tissue facies in response to deltaic progradation on the shallow shelf a marine regression occured towards the close of the early maestrichtian emplacing the coastal inertinite facies the major marine transgression occured near the end of the early maestrichtian developing a farther offshore amorphous debris facies on an expanded continental shelf which persisted through the late maestrichtian the inertinite facies returned during marine regression in the approximate position of the maestrichtian danian boudnary

the calcareous nannofossil response to the end cretaceous warm event in the tropical pacific abstract the response of calcareous nannofossils to the end cretaceous warming is investigated in the tropical pacific dsdp site 577a shatsky rise through the record of species richness shannon diversity distribution patterns and statistical treatments this event is marked by a strong acme of the tropical species micula murus and is accompanied by a decrease of placozygus spiralis the disappearance of biscutum constans and a decrease in bulk 13c indicative of a decrease in primary productivity an increase in abundance of other micula species at site 577a and a drop in species richness recorded in all sites of shatsky rise suggest stressed environmental conditions coincident with the end cretaceous warming the acme of m murus at shatsky rise and in the atlantic ocean is recorded within magnetochron c29r and correlates 1 with the intense warming as expressed in intermediate waters through the 18o of benthic foraminifera and in surface waters through poleward migration reduced diversity and dwarfism in planktonic foraminifer assemblages 2 with a sharp decline in marine 187os 188os chemical marker of deccan volcanic activity and 3 with a rise in the atmospheric pco2 record of terrestrial plants in texas usa probably triggered by deccan volcanic degassing however a drop of calcareous nannofossil cool water taxa in the equatorial and south atlantic as well as a first rise in abundance of m murus in the south atlantic and tropical pacific occur in the topmost part of chron c30n and correlates with the rise in palaeotemperature record of terrestrial plants in north dakota usa this suggests that initiation of the warming in the atmosphere and surface waters may predate the striking warming of intermediate water masses by 150 200 kyr the coincidence and the links between climate change volcanism geochemical and biotic events at the end of the maastrichtian thus remain to be fully elucidated

tectonic forcings of maastrichtian ocean climate evolution a global compilation of deep sea isotopic records suggests that maastrichtian ocean climate evolution tvas tectonically driven during the early maastrichtian the atlantic intermediate deep ocean was isolated from the pacific indian and southern oceans deep water formed in the high latitude north atlantic and north pacific at the early late maastrichtian boundary a major reorganization of oceanic circulation patterns occurred resulting in the development of a thermohaline circulation system similar to that of the modem oceans a combination of isotopic and plate kinematic data suggests that this event was triggered by the final breaching of tectonic sills in the south atlantic and the initiation of north south flow of intermediate and deep water in the atlantic the onset of laramide tectonism during the mid maastrichtian led to the concurrent draining of major epicontinental seaways together these events caused cooling increased latitudinal temperature gradients increased ventilation of the deep ocean and affected a range of marine biota

faunal turnover at the end of the cretaceous in the north pacific region implications from combined magnetostratigraphy and biostratigraphy of the maastrichtian senpohshi formation in the eastern hokkaido island northern japan abstract a combined magnetostratigraphic and biostratigraphic study has been performed on the maastrichtian senpohshi formation in eastern hokkaido island northern japan which is an approximately 1300 m thick section mainly composed of hemipelagic mudstone the identification of magnetic polarity was possible at 51 horizons whereby four magnetozones were recognized these magnetozones were correlatable to geomagnetic polarity chrons c31r to c30n suggesting that the age of the senpohshi formation is spanning from middle to upper part of the maastrichtian ca 69 67 ma the magnetostratigraphy of the senpohshi formation established in this study enables a direct age correlation to the maastrichtian successions in other regions thus this detailed chronology of the formation contributes to paleontological studies of the maastrichtian in the north pacific region for instance this magnetostratigraphic age assessment implies the following 1 the stratigraphic range of the ammonite pachydiscus flexuosus contains polarity chrons from the lower part of c31r to the lower part of c31n 2 the first occurrence fo of the calcareous nannofossil nephrolithus frequens in the north pacific region is correlatable to polarity chron c30n or below and 3 the fo of the bivalve inoceramus awajiensis is located within polarity chrons from c31r to the upper part of c31n this suggests that the inoceramid extinction event in the north pacific region might have occurred during polarity chrons from c31r to the upper part of c31n ca 70 5 67 8 ma which is 2 3 5 0 myr prior to the cretaceous paleogene boundary the trend of the maastrichtian faunal turnover in the north pacific is well consistent with those of other regions brings a new evidence for understanding the global faunal turnover in the maastrichtian just before cretaceous paleogene mass extinction

calcareous nannofossil evidence for the existence of the gulf stream during the late maastrichtian 1 upper maastrichtian calcareous nannofossil assemblages from eight cores on the south carolina coastal plain onshore set and three deep sea drilling sites from the continental slope and abyssal hills offshore set were analyzed by correlation and principal component analysis to examine the ancient surface water thermal structure in addition a temperature index derived from independently published paleobiogeographic information was applied to the sample data all three methods indicate a strong separation of the samples into onshore and offshore sets with the offshore data set exhibiting significantly warmer paleotemperatures the great disparity between these two sample sets indicates that there was a strong thermal contrast between the onshore and offshore surface water masses that persisted throughout the late maastrichtian despite evident short term changes in fertility productivity and community structure this suggests the gulf stream was present as a major oceanographic feature during the late maastrichtian

ammonite correlation of the uppermost campanian of western europe the u s gulf coast atlantic seaboard and western interior and the numerical age of the base of the maastrichtian

reworked palynomorphs and their use in the determination of sedimentary cycles the permian triassic sequence in the subsurface of israel was deposited near the margin of the arabian craton which was a major source for both reworked organic and inorganic detritus three major depositional cycles are identified in this sequence each consisting of a transgressive interval and a regressive interval analysis of the stratigraphic variation in the amounts of reworked palynomorphs indicates that they are most abundant in regressive intervals this is considered to be a result of changes in the extent of exposed land which was the source for the reworked palynomorphs or of changes in the transportational regime stratigraphic variation in the abundance of reworked organic detritus may be useful for identifying depositional cycles that are not otherwise evident in the rock record

calcareous dinoflagellate associations and maastrichtian tertiary climatic change in a high latitude core odp hole 689b maud rise weddell sea abstract the distribution of calcareous dinoflagellates has been analysed for the maastrichtian miocene interval of ocean drilling project hole 689b maud rise weddell sea the investigation thus represents a primary evaluation of the long term evolution in high latitude calcareous dinoflagellate assemblages during the transition from a relatively warm late cretaceous to a cold neogene climate major assemblage changes during this interval occurred in characteristic steps 1 an increase in relative abundance of tangentially structured species particularly operculodinella operculata at the cretaceous tertiary boundary 2 a diversity decrease and several first and last appearances across the middle late eocene boundary possibly attributed to increased climate cooling 3 a diversity decrease associated with the dominance of calciodinellum levantinum in the late early oligocene 4 the reappearance and dominance of pirumella edgarii in the early miocene probably reflecting a warming trend 5 monogeneric assemblages dominated by caracomia spp denoting strong middle miocene cooling the results not only extend the biogeographic ranges of many taxa into the antarctic region but also indicate that the evolution of high latitude calcareous dinoflagellate assemblages parallels the changing environmental conditions in the course of the cenozoic climate transition therefore calcareous dinoflagellates contribute to our understanding of the biotic effects associated with palaeoenvironmental changes and might possess the potential for reconstructing past conditions the flora in the core includes one new taxon caracomia arctica forma spinosa hildebrand habel and streng forma nov additionally two new combinations are proposed fuettererella deflandrei kamptner 1956 hildebrand habel and streng comb nov and fuettererella flora futterer 1990 hildebrand habel and streng comb nov

seawater sr isotopes at the cretaceous tertiary boundary abstract seawater 87 sr 86 sr values increase abruptly by 28 10 6 across the cretaceous tertiary boundary ktb this small but rapid shift is superimposed on the larger scale structure of the seawater sr isotope curve the time scale of radiogenic sr addition appears to be too rapid to reconcile with sources associated with volcanism and we show that the amount of sr required to produce even this small increase is too large to be derived from 1 a kt bolide of the size constrained by the ir anomaly 2 continental crust ejecta from the impact of such a bolide 3 soot from global wildfires initiated by an impact or 4 any combination of these sources the probable source of the radiogenic sr is enhanced continental weathering but the high rate of increase appears to rule out processes such as sea level regression glaciation or tectonism a plausible mechanism for rapid addition of radiogenic sr to the oceans is enhanced weathering associated with globally distributed acid rain ph 1 which is a proposed by product of a bolide impact 51 epsl vol 83

strontium isotope stratigraphy for late cretaceous time direct numerical calibration of the sr isotope curve based on the us western interior the 87sr 86sr of sr in macrofossil carbonate from upper cretaceous strata deposited in the western interior seaway usa provides a sr isotope curve for late cretaceous time cenomanian early maastrichtian the curve is calibrated biostratigraphically against the most refined ammonite zonation known for the interval and calibrated numerically with 39ar 40ar dates for 20 bentonites within the sequence marine 87sr 86sr decreased from 0 70743 in the late middle cenomanian to a late cretaceous minimum of 0 70730 in the late turonian 89 ma from the minimum 87sr 86sr increased through a middle campanian inflexion minimum at 77 ma maximum at 78 80 ma to reach 0 70772 at the campanian maastrichtian boundary thereafter 87sr 86sr increased through a very short inflexion in the latest early maastrichtian to the limit of our sampling in the earliest late maastrichtian the inflexions provide global event markers for correlation for most of the period covered by our curve resolution in dating and correlation of 0 8 ma should be achievable with our 2 s d precision in measurement of 18 10 6 our 87sr 86sr data show no evidence of having been affected by influxes of freshwater into the us western interior seaway from rivers including those that drained the sevier orogenic belt

palynofacies and sea level changes in the middle coniacian late campanian late cretaceous of the east coast basin new zealand abstract a palynofacies analysis of four sections through the paton and herring formations of the east coast basin in southern marlborough indicates that the two formations were deposited on the inner to mid shelf in a marine environment with conspicuous input of plant material from adjacent land area the paton formation was deposited on the inner to mid shelf under oxic conditions and in proximity to a river delta possibly in a deltafront setting its lower part is clearly less marine than its upper part pointing to an overall deepening trend with time the deposition of the herring formation took place farther offshore on the mid shelf in a mud dominated environment under poorly oxygenated conditions at the sediment water interface following a landward shift of shoreline a stratigraphic analysis of changes in palynofacies and lithology through the four sections allows a breakdown of the succession into seven depositional sequences separated by unconformities or their correlative conformities a regional sea level curve for the middle coniacian upper campanian in the east coast basin is proposed on the basis of the inferred sequences and chronostratigraphic control from dinoflagellate biostratigraphy the sea level cycles thus inferred for the east coast basin show a poor correlation with the re scaled haq cycle chart suggesting that regional tectonics rather than eustasi controlled the east coast basin sequences

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

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

the origin of the clay minerals at the cretaceous tertiary boundary in denmark the distinctive mg smectite that is the predominant clay mineral in the cretaceous tertiary k t boundary marl at stevns klint denmark that is the fish clay which has been previously believed to have formed from impact derived glass is also present in the upper of two marls of probable early danian age at limhamn quarry sweden approximately 8 m above the k t boundary this danian marl is devoid of anomalous iridium we contend that this mg smectite is the result of alteration of a volcanic ash precursor perhaps reworked and that impact debris is a relatively minor component of the k t boundary marls studied herein k ar dates demonstrate that caledonian detrital potassic phases that is illite are present in the coarse clay fraction of the fish clay the fish clay is thus composed predominantly of volcanic detrital phases and lesser amounts of impact phases in addition we have discovered subhedral labradorite in the organic rich black clay of layer iii of the fish clay therefore we suggest that pyroclastic basaltic volcanism was the predominant progenitor of the boundary clay unit and is responsible for its high mg content our results indicate that the main carrier of ir in the k t boundary marls is of submicron size and that ir is mobile during diagenesis and or weathering in addition our results show that pt and au are present in the upper limhamn marl and for comparison in the permian kupferschiefer shale at amounts comparable to those of the k t boundary it is thus possible that some or much of the pt and au at the k t boundary is derived from nonimpact sources similar to those that apparently contributed to the parts per billion concentrations of pt and au in the permian kupferschiefer shale we cannot reject the impact hypothesis summarily because shocked quartz with multiple planar sets is distinct to the k t boundary and this distinctive shocked quartz has not yet been identified in distal volcanic tephras or flows if shocked quartz is of impact origin then the collision of either a smaller asteroid or a comet is more consistent with the relatively small amount of impact derived material in the fish clay alternatively if shocked quartz is proven to be formed by explosive volcanism then our evidence would permit explaining the k t boundary events as entirely due to volcanism rather than impact

an expanded cretaceous tertiary transition in a pelagic setting of the southern alps central western tethys abstract an integrated micropalaeontological planktonic foraminifera and calcareous nannofossils mineralogical and stable isotope investigation was carried out across the cretaceous tertiary k t boundary in a previously undescribed hemipelagic section forada section cropping out in the piave river valley southern alps belluno province ne italy our results suggest that an apparently complete k t transition with an expanded basal danian is preserved in the forada section the k t boundary is marked by a ca 1 5 cm thick clay interval intercalated in the pelagic carbonates of the scaglia rossa formation the boundary clay characterised by an iridium anomaly is constituted by a basal 1 2 mm thick green layer and an overlying red layer below the boundary clay the calcareous nannofossil micula murus zone and the planktonic foraminiferal plummerita hankteninoides zone that characterise the terminal maastrichtian in complete sections have been identified virtually all the calcareous plankton biohorizons normally utilised in the early danian have been recognised interestingly the ranking of the various biohorizons is the same observed elsewhere if considering the single plankton groups separately while several inconsistencies emerge if considering the relative succession of the two calcareous plankton groups simultaneously we caution to infer hiatuses on a section based only on the spacing of the biohorizons of a single group because of the risk of diachroneities in the stressed early danian environment by comparing the distance of the key biohorizons i e the first occurrence fo of cruciplacolithus primus and the last occurrence lo of parvularugoglobigerina eugubina from the boundary clay at forada and in other complete classical sections we have inferred that the early danian is expanded in the forada section the section seems ideally suited for studying the recovery pattern of the pelagic ecosystem and calcareous plankton communities in the aftermath of the k t catastrophe in a pelagic setting of the western central tethys the adaptive radiation of planktonic foraminifera was very rapid in contrast with the delayed diversification of coccolithophores the latter show a ca 21 cm thick dead zone that is followed by a long lasting survival interval ca 180 cm thick that might represent some 200 kyr dominated by persistent cretaceous coccolithophores and calcareous dinoflagellate thoracosphaera spp the temporal pattern in recovery of the coccolithophore and planktonic foraminiferal communities is decoupled as well pointing to their varying sensitivities to the k t perturbation it appears that the ecospace occupied by coccolithophores in the terminal maastrichtian was occupied in the initial danian by the calcareous dinoflagellates thoracosphaera spp that remained a significant component of the assemblage up to the base of the prinsius dimorphosus zone of romein romein a j t 1979 lineages in early paleogene calcareous nannoplankton utrecht micropaleontological bulletins 22 231 pp probably in the early chron c29n on the contrary planktonic foraminifera seem to reach stable conditions earlier in the late cruciplacolithus primus zone the early danian interval considered is also characterised by low sr ca ratio of the biogenic carbonates that would suggest dramatically low coccolithophore productivity conditions in agreement with previous flux studies we speculate that the altered ecological structure of phytoplankton community and the low productivity of coccolithophores severely affected the efficiency of the transfer of organic carbon from the photic zone to the deep ocean thus supporting the early danian living ocean model of d hondt et al d hondt s donaghay p zachos j c luttenberg d lindinger m 1998 organic carbon fluxes and ecological recovery from the cretaceous tertiary mass extinction science 282 276 279

oligocene miocene strontium isotopes stratigraphic revisions and correlations to an inferred glacioeustatic record this study tests and improves on previously published early and middle miocene 87sr 86sr marine correlations presents sr isotopic age correlations for this interval using the new timescale of cande and kent 1992 and evaluates sr isotopic changes against an inferred glacioeustatic proxy we generated a latest oligocene to early late miocene 87sr 86sr isotope record from ocean drilling program odp hole 747a this site provides an excellent magnetostratigraphic record during most of this interval for independent age estimates very good foraminiferal preservation and excellent core recovery comparisons of new 87sr 86sr data from hole 747a with previously published data from deep sea drilling project dsdp sites 608 miller et al 1991a and 588 hodell et al 1991 yield the following results 1 confirmation and refinement of the early miocene sr isotope changes 2 improved definition of the timing of the changes in slope of 87sr 86sr near 15 4 ma and 22 8 ma 3 improved sr isotopic age resolution for the middle miocene with resolution as good as 0 7 m y and 4 identification of an inflection in the sr isotope record at 28 0 ma based on the combined records from dsdp site 522 miller et al 1988 and odp hole 747a we have been unable to determine the cause of middle miocene offset between site 588 and hole 747a data although we believe it may be attributed to problems in the age assignments for hole 588a for the interval 14 11 ma and site 747 for the interval 11 8 ma because hole 747a results provide a better chronology than site 588 for most of the miocene and a better middle miocene sr isotope record than site 608 we propose that hole 747a serves as the best reference section for miocene 87sr 86sr variations from ca 23 to 11 ma using 87sr 86sr data from sites 522 608 and 747a we relate late eocene to early miocene inflections in the 87sr 86sr isotope record to oxygen isotope increases and decreases inferred to represent glacioeustatic events the decreases deglaciations observed in the 18o record apparently lead the 87sr 86sr inflections by 1 to 1 5 m y

palynological palynofacies paleoenvironmental and organic geochemical studies on the upper cretaceous succession of the gptsw 7 well north western desert egypt abstract the present study of the abu roash and bahariya formations in well gptsw 7 refines our understanding of the subsurface cretaceous of the north western desert of egypt our investigations are based on the palynological analyses of 71 cuttings samples of which 24 have also been analyzed for geochemistry in addition to 3 sidewall cores analyzed for vitrinite reflectance r o four palynological zones and three subzones in addition to a poorly fossiliferous interval ranging in age from coniacian santonian to early cenomanian are proposed these include a poorly fossiliferous interval coniacian santonian dinogymnium vozzhennikovae interval zone late to middle turonian ephedripites ambiguus ephedripites multicostatus foveotricolpites giganteus foveotricolpites gigantoreticultus assemblage zone early turonian classopollis brasiliensis interval zone late to middle cenomanian and afropollis jardinus interval zone early cenomanian the succeeding subzones are afropollis kahramanensis interval subzone elaterosporites klaszii interval subzone and cretacaeiporites densimurus interval subzone all of early cenomanian age total organic carbon toc and rock eval pyrolysis and palynofacies analyses indicate that the bahariya formation and the abu roash g member are primarily of kerogen iii type and hence gas prone suggesting a strong influence of hydrogen enriched organic matter the abu roash a c e members may also be gas prone type iii kerogen and appear to contain highly oxidized terrestrial organic matter in contrast the abu roash f member has very high toc and hi values and contains a very high proportion of amorphous organic matter aom indicating a highly oil prone facies while this finding is not unexpected for anoxic black shale it contrasts with earlier studies that suggest a gas prone nature r o measurements show that the bahariya formation represents an immature early genesis dry gas phase this is also true for all investigated samples from the abu roash and bahariya formations based on their low thermal alteration index tai quantitative and qualitative analyses of both the palynoflora and palynofacies show that the abu roash a and c members b is missing both of coniacian santonian age represent oxic proximal and distal shelf environment the abu roash d and e members dated as turonian represent oxic proximal shelf whereas the cenomanian abu roash f member was deposited in a distal suboxic anoxic basin the cenomanian abu roash g member and the bahariya formation were deposited in a shallow marine and shallow marine to fluvio deltaic setting respectively the senonian palmae province is recognized in the palynoflora by the presence of proteacidites auriculiidites reticulatus ariadnaesporites gabonisporis vigourouxii on the other hand the albian cenomanian elaterates province is characterized by the presence of steevesipollenites gnetaceaepollenites elaterocolpites elaterosporites elateroplicites senegalosporites sofrepites afropollis and cretacaeiporites

changes in the pelagic fine fraction carbonate sedimentation during the cretaceous paleocene transition contribution of the separation technique to the study of bidart section abstract the bidart section southwestern france displays an almost complete late maastrichtian early danian transition as the cretaceous paleocene k p crisis mainly affects carbonate producers the aim of this study is to precisely evaluate the evolution of pelagic sediments composition across the boundary a new protocol for separation of fine carbonates into discrete size fractions was used 1 to precisely evaluate in weight of carbonate and not only number of particles per gram of rock the contribution of each carbonate component type foraminifera calcareous nannofossils and nonbiogenic carbonates calcite microparticles and calcareous macrocrystals and 2 to measure their isotopic signature and thus constrain the origin of these carbonate particles the maastrichtian pelagic carbonates are mostly biogenic 70 of the bulk carbonate but also contain nonbiogenic carbonates calcite microparticles 4 m due to their isotopic signature calcite microparticles cannot result from fragmentation and partial dissolution of biogenic remains and the most likely origin appears to be early diagenetic processes and or export from shallow water platforms the calcareous macrocrystals derive from an early diagenetic process the lowermost danian sediments are dominated by nonbiogenic carbonates between 50 and 80 of the bulk carbonate nevertheless two kinds of biogenic components are present thoracosphaera operculata and maastrichtian like calcareous nannofossils thoracosphaera operculata is an opportunistic calcareous dinoflagellate which frequently occurs at high abundances in basal danian sediments and is certainly in situ this is confirmed by it showing a danian isotopic signature the maastrichtian like calcareous nannofossils are nannofossils of taxa that indisputably occur in the maastrichtian but which do not occur consistently in later danian strata they show a maastrichtian type isotopic signature which strongly supports the inference that they are mainly reworked from the maastrichtian this study shows that nonbiogenic carbonates are important components of the pelagic carbonate even during periods of normal sedimentation in the crisis interval the biogenic carbonate production drops sharply while calcite microparticles and carbonate macrocrystals remain almost unaffected and represent the major part of the carbonate in the earliest danian sediments finally the sediments return to a composition similar to that of the maastrichtian in m pseudobulloides foraminifera zone

topography and significance of a basinwide sequence bounding erosion surface in the cretaceous cardium formation alberta canada abstract the cardium formation turonian coniacian upper cretaceous of the western interior seaway alberta contains six marine sandier upward successions bounded by seven basin wide erosion surfaces in the subsurface erosion surface e5 is associated with major oil and gas fields and is penetrated by thousands of wells a topographic map of e5 based on 6126 well logs and over 1100 measured cores shows a series of subparallel elongate highs steps and lows which trend northwest southeast parallel to tectonic trends and to the actively rising cordillera to the southwest the steps are about 10 km apart and the relative relief step to adjacent low is up to 25 m the steps are asymmetrical with a steeper face to the northeast the e5 erosion surface cuts into offshore marine hummock cross stratified sandstones and interbedded mudstones and it records a lowering of relative sea level our interpretation suggests that erosion was in neither a fully subaqueous nor a fully subaerial environment instead it involved relative sea level lowering and subaerial erosion followed by major modification of the landscape during transgressive shoreface erosion at times of relative stillstand during overall transgression gravel was supplied to the shoreface and was reworked a short distance alongshore by waves these conglomerates now form important oil and gas reservoirs the asymmetry of the steps and lows indicates that the originally flat sea floor was tilted northeastward immediately before erosion giving a gradient of about 1 1000 during transgression shorefaces were incised into the tilted surface to form a stepped morphology also during transgression the sea floor was gradually restored to its pre tilting position each of the six marine sandier upward sequences along with the erosion surface at the top occupies an average of 470 000 years and we estimate that transgression took at least 100 000 to 200 000 years

early maastrichtian carbon cycle perturbation and cooling event implications from the south atlantic ocean published stable isotope records in marine carbonate are characterized by a positive 18o excursion associated with a negative 13c shift during the early maastrichtian however the cause and even the precise timing of these excursions remain uncertain we have generated high resolution foraminiferal stable isotope and grey scale records for the latest campanian to early maastrichtian 73 68 ma at two ocean drilling program sites 525 walvis ridge and 690 weddell sea we demonstrate that the negative 13c excursion is decoupled from the 18o increase with a lag of about 600 kyr our 13c records both planktic and benthic show an amplitude for the negative excursion of 0 7 that falls between about 72 1 and 70 7 ma our planktic 18o records indicate an overall increase of 1 2 from 73 to 68 ma at site 690 whereas at site 525 they record a slightly smaller increase 1 that peaks around 70 1 ma with decreasing values thereafter our benthic 18o data indicate an increase of 1 5 at site 525 and 0 7 at site 690 between about 71 4 and 69 9 ma benthic 18o values show different baseline values at the two sites before and after the excursion but the larger increase at site 525 means that the values attained at the peak of the excursion are similar at the two sites we interpret this observation in terms of water mass changes the excursion is interpreted to reflect a cooling of bottom waters in response to the strengthening contribution of intermediate to deep water production in the high southern latitudes rather than increased ice volume the associated carbon cycle perturbations that we observe are interpreted to reflect a weakening of surface water stratification and increased productivity as supported by our grey value data

uppermost campanian maestrichtian strontium isotopic biostratigraphic and sequence stratigraphic framework of the new jersey coastal plain firm stratigraphic correlations are needed to evaluate the global significance of unconformity bounded units sequences we correlate the well developed uppermost campanian and maestrichtian sequences of the new jersey coastal plain to the geomagnetic polarity time scale gpts by integrating sr isotopic stratigraphy and biostratigraphy to do this we developed a maestrichtian ca 73 65 ma sr isotopic reference section at deep sea drilling project hole 525a in the southeastern atlantic ocean maestrichtian strata can then be dated by measuring their 87 sr 86 sr composition calibrating to the gpts of s c cande and d v kent 1993 personal commun and using the equation age ma 37 326 894 52 639 89 87 sr 86 sr sr stratigraphic resolution for the maestrichtian is estimated as 1 2 to 2 m y at least two unconformity bounded units comprise the uppermost campanian to maestrichtian strata in new jersey the lower one the marshalltown sequence is assigned to calcareous nannofossil zones cc20 21 nc19 and cc22b nc20 it ranges in age from 74 1 to 69 9 ma based on sr isotope age estimates the overlying navesink sequence is assigned to calcareous nannoplankton zones cc25 26 nc21 23 it ranges in age from 69 3 to 65 ma based on sr isotope age estimates the upper part of this sequence the tinton formation has no calcareous planktonic control sr isotopes provide an age estimate of 66 1 2 ma latest maestrichtian sequence boundaries at the base and the top of the marshalltown sequence match boundaries elsewhere in the atlantic coastal plain owens and gohn 1985 and the inferred global sea level record of haq et al 1987 they support eustatic changes as the mechanism controlling depositional history of this sequence however the latest maestrichtian record in new jersey does not agree with haq et al 1987 we attribute this to correlation and time scale differences near the cretaceous paleogene boundary high sedimentation rates in the latest maestrichtian of new jersey shrewsbury member of the red bank formation and the tinton formation suggest tectonic uplift and or rapid progradation during deposition of the highstand systems tract

new latitude based nannofossil zonations for the campanian maastrichtian of the south atlantic ocean and their paleoceanographic implications the global evolution of calcareous nannofossils during the campanian maastrichtian interval is not fully understood and nannofossil zonations for the central and south atlantic ocean are yet to be constructed here we test the applicability of previous calcareous nannofossil zonations developed for other ocean basins for biostratigraphy in the south atlantic ocean and refine campanian maastrichtian biostratigraphy in the region we document calcareous nannofossil distributions at deep sea drilling project dsdp and ocean drilling program odp sites from the high mid and low latitudes in the south atlantic ocean dsdp sites 354 356 511 525a and 530a and odp sites 690c 700b 661a and 1258a combining nannofossil occurrences with magnetostratigraphic schemes previously constructed for some of the sites we propose three new zonations tied to the global magnetostratigraphic chrons with distinct bio horizons selected at different latitudinal regions in this study we present detailed definitions of new south atlantic ocean low latitude sal south atlantic mid latitude sam and south atlantic high latitude sah zonations we identified significant diachronism of some species between latitudes throughout the campanian and maastrichtian these species diachronism mainly between zonal markers from low and mid latitudes during the late maastrichtian was probably related to migration patterns due to fundamental paleoceanographic changes

calcareous nannofossil and dinoflagellate stratigraphy across the cretaceous tertiary boundary at hor hahar israel in israel the cretaceous tertiary k t boundary at hor hahar occurs within the interval from the top of the ghareb formation maastrichtian to just below the horizon of dark marl and clay within the overlying taqiye formation paleocene the studied interval contains all the calcareous nannofossil zones micula prinsii latest maastrichtian markalius inversus np1 earliest paleocene andcruciplacolithus tenuis np2 early paleocene they correlate in sequence with theabathomphalus mayaroensis p0 p1a p1b and p1c planktic foraminiferal zones the palynological assemblages consist mainly of dinocysts with only few pollen grains and spores these assemblages are used to interpret five stratigraphic phases of environmental change across the k t boundary in the hor hahar section in the latest maastrichtian there is an overwhelming dominance of the nannofossilmicula decussata which probably reflects environmental stress preceding the terminal cretaceous mass extinction a nearshore marine environment at the boundary is suggested by the increase in number of specimens of the dinocystcyclonephelium and by the predominance of terrigenous organic matter sediment there followed two episodes of transgression and regression the calcareous cyst producing dinoflagellatethoracosphaera futterer 1976 becomes dominant in two episodes at the boundary and approximately one meter above it it alternates in abundance with the organic walled dinoflagellates which suggests that different environmental parameters were operating for each group maastrichtian dinocysts decline in abundance toward the k t boundary they reach greatest abundance and species diversity at the same strata where foraminiferids recover after their mass extinction at the boundary calcareous nannofossils recover only later in the early paleocene changes in 13c and total organic carbon as as well as dinocyst and nannofossil composition indicate an episode of strong ecological stress about one meter above the boundary

middle to late miocene caribbean dinoflagellate assemblages and palynofacies dsdp leg 15 site 153 abstract changes in oceanic circulation and productivity patterns near central america have been explained using numerous different tools such as tectonics geochemistry and micropaleontology this paper aims to contribute to this discussion through the study of dinoflagellates and palynofacies in the drill core from dsdp site 153 based on foraminiferal data the studied section is divided into the middle and upper miocene and our dinoflagellate events also support an age model of 15 to 8 ma indval ecological indexes and the p g dinoflagellate ratios were used to develop paleoenvironmental inferences the indicator species are operculodinium centrocarpum and tectatodinium pellitum for the mm1 interval spiniferites spp and impagidinium strialatum for mm2 and selenopemphix armageddonensis lejeunecysta spp and l tenella for um3 intervals mm1 and mm2 are characterized by a dominance of gonyaulacoids and inner to outer neritic environments the um3 interval is interpreted as an outer neritic environment in the base middle portion and inner neritic in the uppermost part with a shift from gonyaulacoid to peridinioid dominance suggesting an increase in productivity during the middle miocene productivity is low due to intermittent marine circulation restrictions in the caribbean sea and there is a slight increase during the upper miocene following reestablishment of the global oceanic circulation this is directly connected to the occurrence of geotectonic and paleoceanographic events in the region during the miocene mainly by mass movements such as the panama gateway and the opening of the pedro channel to the north changing the surface conditions in the caribbean sea

influence of bottom friction on sea surface roughness and its impact on shallow water wind wave modeling abstract using a selected subset of the measured data obtained in shallow waters near vindeby denmark during rasex riso air sea experiment the role of bottom friction dissipation in predicting wind waves not swell is assessed with a third generation numerical wind wave model the rasex measurement site is located in relatively shallow waters depths of about 3 to 4 m in an area where the waves are predominantly fetch limited i e maximum fetch of about 20 km the bottom friction dissipation source term is modeled using the linearized bottom friction formulation this formulation contains a dissipation coefficient cf which depends on wave and sediment properties in the numerical investigations we considered three cases i a constant value for cf as obtained in the jonswap experiment ii a constant geometric roughness kn and iii a constant median sediment size d50 in the latter case the bed is treated as a mobile bed and the geometric roughness is related to the dimensions of wave f

fungal event and palynological record of ecological crisis and recovery across the permian triassic boundary the end of the permian period was marked by the most severe mass extinction in the geologic record detailed quantitative study of pollen and spores from shallow marine deposits spanning the permian triassic p tr boundary in israel reveals a sequence of palynological ecological stages reflecting a major crisis among land plants the disappearance of the gymnosperm dominated palynoflora of the late permian lueckisporites virkkiae zone is recorded at a claystone horizon containing almost exclusively abundant fungal remains and carbonized terrestrial plant debris this fungal spike is followed by a zone dominated by marine acritarchs and a succession showing ecological recovery with abundantlycopodsporesandeventualreappearanceofbisaccategymnospermpolleninthe earlytriassic thelatestpermianproliferationoffungiisrecognizableworldwideandcan be correlated with other paleontological and geochemical markers of a global ecological disaster

sudden death at the end of the mesozoic abstract a paleoecological analysis of the fossil record before and after the cretaceous tertiary boundary indicates that the widespread extinctions and biological stresses around the boundary are best explained in terms of a sudden significant but short temperature rise l alvarez and co authors having found an enrichment in iridium at the same boundary postulated that it was associated with the impact of an extraterrestrial body if this body struck the ocean the water injected into the atmosphere may have led to a transient increase in the global surface temperature this temperature pulse may have been primarily responsible for the effects observed in the biosphere the pattern of extinction of higher plant species suggests that splash down occurred in the northern pacific bering sea area

the equation of state of a molten komatiite 2 application to komatiite petrogenesis and the hadean mantle new experimental data for the equation of state of a komatiitic liquid were used to model adiabatic melting in a peridotitic mantle if komatiites are formed by 30 partial melting of a peridotitic mantle then komatiites generated by adiabatic melting come from source regions that began their unmelted ascent in the lower transition zone 500 670 km or the lower mantle 670 km the great depth of incipient melting implied by this model suggests that komatiitic liquids may form in a pressure regime where they are denser than their coexisting crystals possibly the bulk mantle although komatiitic magmas are thought to separate from residual crystals in the mantle at a temperature 200 c greater than modem mid ocean ridge basalts morbs their ultimate sources are predicted to be diapirs that if adiabatically decompressed from initially solid mantle were more than 700 c hotter than the sources of morbs and were derived from great depth we also studied the evolution of an initially molten mantle i e a magma ocean our model considers the thermal structure of the magma ocean density constraints on crystal segregation and approximate phase relationships for a nominally chondritic mantle crystallization will begin at the core mantle boundary perovskite buoyancy at 70 gpa may lead to a compositionally stratified lower mantle with iron enriched magnesiowustite content increasing with depth large convective velocities in the magma ocean would prohibit crystal liquid fractionation by settling or flotation until quiescent boundary layers form such boundary layers could form when the crystal content of the magma reaches a critical value near 44 vol and in the late stages of crystallization around unmelted blocks of foundered protocrust matrix compaction and diapirism could also lead to fractionation effects the upper mantle could be depleted or enriched in perovskite components relative to the bulk mantle olivine neutral buoyancy may lead to the formation of a dunite septum in the upper mantle partitioning the ocean into upper and lower reservoirs but this septum must be permeable

glauconite composition and morphology shocked quartz and the origin of the cretaceous main fossiliferous layer mfl in southern new jersey u s a abstract the main fossiliferous layer mfl is a concentration of vertebrate and invertebrate fossils 20 to 30 cm thick preserved in a sequence of glauconitic sand at or near the cretaceous paleogene boundary in the new jersey usa coastal plain several hypotheses have been proposed to explain the origin and age of the mfl including marine transgression and formation of lag deposits of reworked bones and shells formation of a condensed section and attritional accumulation of fossil material and catastrophic collapse of late cretaceous ecosystems following the end cretaceous bolide impact at chicxulub we use new data on glauconite morphology concentrations geochemistry and presence of shocked quartz coupled with previous data on sedimentology taphonomy and rare earth element geochemistry of fossil vertebrates to interpret the genesis of the mfl glauconite concentration and maturity steadily increases from latest cretaceous sediments of the navesink new egypt formation through the mfl and into the paleogene upper hornerstown formation suggesting that marine transgression and decreasing sedimentation rates were a factor in the formation of the glauconite but not the mfl rare earth element patterns in fossil bones from the mfl which are acquired during fossilization are different from those of cretaceous and paleogene specimens indicating that vertebrate remains in the mfl fossilized in situ and were not reworked from older underlying units vertebrate fossils from the mfl are preserved as isolated to articulated specimens while isolated specimens would be common in a transgressive lag articulated specimens would not articulated specimens could be concentrated by attritional accumulation along a defined surface during a period of slow sedimentation but the lack of a distinct increase in glauconite maturity or concentrations of elements associated with heavy mineral accumulations at the navesink new egypt hornerstown contact or mfl which would be expected during a period of reduced sedimentation hiatus or unconformity are absent at the localities studied shocked quartz was identified in a burrow fill directly beneath the mfl at the contact of the navesink and hornerstown formations clay clasts with latest cretaceous microfossils along with reworked invertebrate fossils with infills of latest cretaceous sediment have been recovered from the mfl the association of shocked quartz mixture of isolated and articulated vertebrates with distinct rare earth signatures lack of a punctuated period of increased glauconite maturity and presence of reworked late cretaceous invertebrates and clay clasts with late cretaceous microfossils suggests that the mfl may represent a thanatocoenosis that was the direct result of environmental disturbance associated with the end cretaceous impact event at chicxulub