deep water in the late maastrichtian ocean 1 stable isotopic data from benthic foraminifera indicate the occurrence of at least three deepwater masses in the late maastrichtian ocean given mean oceanic 18ow of 1 0 the temperature of the coolest intermediate depth waters was 5 7 c that of the deepest waters was 10 c and that of the warmest intermediate waters was 13 15 c the cool intermediate depth water mass probably originated in the high latitude southern ocean the deepest waters originated at least partly in the northern atlantic the source region for the warmest intermediate depth water mass is unknown although much of the late maastrichtian deep water was probably preconditioned for winter sinking by low or middle latitude evaporation no more than 11 of late maastrichtian deep water could have been directly actuated by low latitude sea surface evaporation at least in the southern atlantic and indian oceans heat transport by upwelling of deep water was not the primary cause of mild sea surface and coastal temperatures

biogeography of terminal cretaceous deep sea benthic foraminifera from the atlantic and pacific oceans abstract most species of late cretaceous deep sea benthic foraminifera are believed to be cosmopolitan and therefore to exhibit only minor biogeographical differences in this preliminary report six deep sea drilling project dspd sites from different oceans paleolatitudes and paleodepths were analyzed for terminal cretaceous abyssal bathyal benthic foraminifera in order to investigate their assumed cosmopolitan distribution and the question of whether different faunal compositions are related to time different paleolatitudes and or different paleodepths the material studied was obtained from the low latitude site 465 pacific ocean and the intermediate latitude sites 384 north atlantic and 356 516 525 and 527 south atlantic the material analyzed represents a time slice encompassing the last 20 50 k y of the cretaceous the faunas contain numerous velasco type species such as gavelinella beccariiformis white cibicidoides velascoensis cushman nuttallides truempyi nuttall gaudryina pyramidata cushman and various gyroidinoids and buliminids the results contradict the general assumption of the cosmopolitan nature of late cretaceous deep sea benthic foraminifera advocated in the literature only about 9 of the taxa identified were found to be truly cosmopolitan through their occurrence at all the sites analyzed on the basis of correspondence analysis and relative abundance data three assemblages and three subassemblages were recognized 1 a bathyal abyssal assemblage nuttallinella sp a cibicidoides hyphalus fisher valvalabamina sp evolute form and gyroidinoides spp at the south atlantic sites 356 516 525 and 527 divided into three subassemblages namely a a middle bathyal subassemblage eouvigerina subsculptura mcneil and caldwell tritaxia aspera cushman and g pyramidata at sites 516 and 525 b a lower bathyal subassemblage osangularia sp pyramidina rudita cushman and parker and quadrimorphina camerata brotzen at site 356 and c an abyssal subassemblage gyroidinoides sp c hyperammina bathysiphon gyroidinoides beisseli white and globorotalites sp b at site 527 2 an abyssal assemblage buliminella cf plana cushman and parker and bulimina incisa cushman at the north atlantic site 384 and 3 a middle bathyal assemblage vulvulina sp a osangularia navarroana cushman alabamina sp bulimina velascoensis cushman spiroplectammina spp calcereous forms and bulimina trinitatensis cushman and jarvis at the pacific site 465

benthic foraminiferal turnover across the cretaceous paleogene boundary at agost southeastern spain paleoenvironmental inferences abstract we studied upper cretaceous and lower paleogene benthic foraminifera from the agost section southeastern spain to infer paleobathymetrical changes and paleoenvironmental turnover across the cretaceous paleogene k p transition benthic foraminifera indicate uppermost bathyal depths at agost during the abathomphalus mayaroensis biochron from about 400 kyr before the k p boundary through the early plummerita hantkeninoides biochron about 120 150 kyr before that boundary the depth increased to middle bathyal for the remainder of the cretaceous and remained so for the danian part of the studied section parasubbotina pseudobulloides biochron at least 200 kyr after the k p boundary there were no perceivable bathymetrical changes at the k p boundary where 5 of the species became extinct and the species composition of the benthic foraminiferal fauna changed considerably below the boundary infaunal morphogroups constitute up to 65 73 of the faunas directly above the boundary in the black clays of the lower guembelitria cretacea biozone benthic foraminifera are rare several opportunistic taxa e g the agglutinant haplophragmoides sp have short peaks in relative abundance possibly reflecting low oxygen conditions as well as environmental instability with benthos receiving food from short lived local blooms of primary producers above the clays through the end of the studied interval epifaunal morphogroups dominate up to 70 of the assemblages or there is an even mixture or epifaunal and infaunal morphogroups infaunal groups do not recover to pre extinction relative abundances indicating that the food supply to the benthos did not recover fully over the studied interval about 200 kyr after the k p boundary the benthic foraminiferal faunal changes are compatible with the direct and indirect effects of an asteroid impact which severely destabilized primary producers and the oceanic food web that was dependent upon them

new age estimates and climatostratigraphic correlations for the borrobol and penifiler tephras evidence from abernethy forest scotland the emerging tephrostratigraphy of nw europe spanning the last termination ca 15 9 ka provides the potential for synchronizing marine ice core and terrestrial records but is currently compromised by stratigraphic complications geochemical ambiguity and imprecise age estimates for some layers here we present new tephrostratigraphic radiocarbon and chironomid based palaeotemperature data from abernethy forest scotland that refine the ages and stratigraphic positions of the borrobol and penifiler tephras the borrobol tephra 14 14 13 95 cal ka bp was deposited in a relatively warm period equated with greenland interstadial sub stage gi 1e the younger penifiler tephra 14 09 13 65 cal ka bp is closely associated with a cold oscillation equated with gi 1d we also present evidence for a previously undescribed tephra layer that has a major element chemical signature identical to the vedde ash it is associated with the warming trend at the end of the younger dryas and dates between 11 79 and 11 20 cal ka bp copyright 2011 john wiley sons ltd

recent benthic foraminifera from the continental margin of northwest africa community structure and distribution abstract sediment grab samples were collected at 107 locations along the continental margin of northwest africa these samples form a series of depth transects between the straits of gibraltar and dakar senegal the greater than 250 m size fraction was retained for a census of both the live and dead foraminifera after deleting trace occurrences jaccard and correlation coefficient based cluster analyses were performed to decipher the community structure for this margin the geographic distribution of the four major faunal provinces recognized is conventional in that for both the live and dead assemblages three are related to depth upper slope and shelf middle slope and lower slope and continental rise the biotopes and thanatotopes within these provinces are strongly restricted along vertical or latitudinal boundaries when the data are analysed using jaccard coefficients dendrograms constructed from correlation coefficients emphasize depth related faunal communities dominant species such as cibicides lobatulus trifarina fornasinii planulina ariminensis uvigerina finisterrensis and c wuellerstorfi are generally distributed within a definite depth range along this margin and strongly influence the correlation coefficient based dendrograms other distributions are clearly not depth related but correspond to various environmental variables for example cancris auriculus coarse substrate bolivina subaenariensis oxygen minimum cibicidoides kullenbergi and hoeglundina elegans low organic carbon uvigerina peregrina is also a notable exception to depth dependence in that this dominant species and the province it represents are generally confined to the continental slope south of cape blanc its preference for that region may arise from the high organic carbon and fine grain size of the sediment there from low salinity of the bottom water or from other unknown variables the most important vertical faunal boundary occurs between cape barbas and cape blanc between 22 and 21 n latitude in contrast the canary island ridge intersects the continental margin at a saddle depth of about 1500 m but that physiographic barrier has little effect on provincialism of the deep water benthic foraminifera

laramide thrust generated alluvial fan sedimentation sphinx conglomerate southwestern montana the uppermost cretaceous lower tertiary sphinx conglomerate crops out over an area of approximately 20 km2 8 mi2 in the madison range of southwestern montana the sphinx consists of more than 1 000 m 3 300 ft of synorogenic boulder and cobble conglomerate derived from a late cretaceous laramide uplift that was located in the area presently occupied by the madison river valley palynological and radiometric age data indicate that the sphinx was deposited 75 58 ma and that thrusting and folding of the deposit had largely ceased by 56 ma compositions of sphinx clasts and paleocurrent data indicate that the sphinx was produced by uplift and unroofing of mesozoic and paleozoic rocks located on two thrust sheets to the west and southwest the lower s hinx was deposited on the distal portions of an eastward prograding alluvial fan system clast assemblages and lithofacies indicate that deposition of the middle sphinx was controlled by a combination of progradation in response to ongoing thrusting and an influx of resistant clasts derived from middle paleozoic carbonates in the source area deposition of the upper sphinx was probably controlled by source lithology as the influx of very coarse resistant clasts from middle and lower paleozoic carbonates overwhelmed the fan system s ability to organize its load of sediment by normal fan processes a preliminary facies model for thrust generated alluvial fan deposits predicts intraformational deformation cannibalization of proximal synorogenic fan facies and abrupt compositional breaks in response to episodes of thrusting

a low extinction rate of intermediate water benthic foraminifera at the cretaceous tertiary boundary the contrast between the high extinction rates of calcareous marine plankton and low extinction rates of deep water calcareous benthic foraminifera across the cretaceous tertiary k t boundary is now recognized however the water depth at which the vertical change in extinction rates of marine organisms occurred at the k t boundary is not yet known because of the lack of data on the extinction rates of intermediate water organisms the extinction rate of intermediate water benthic foraminiferal species from kawaruppu hokkaido japan was determined by distinguishing locally extinct species a distinctly low extinction rate 10 for calcareous benthic foraminiferal fauna from the upper part of the intermediate water is documented for the first time this rate is almost equal to the extinction rate of deep water benthic foraminifera 10 and is much smaller than the planktic foraminiferal extinction rate 81 the extinction rate curve for calcareous foraminifera in a vertical water column indicates that a rapid change from a high extinction rate 80 to a low extinction rate 10 took place at a water depth of about 150 m this depth of change is equivalent to the boundary depth between the surface and intermediate waters and between the euphotic and aphotic zones furthermore this coincidence is consistent with the hypothesis that acid rain and a darkness induced breakdown of the marine food chain produced by a cometary or asteroidal impact at the k t boundary were the main causes of the mass extinction of calcareous planktic organisms in surface waters

the cretaceous palaeogene k p boundary at ain settara tunisia restructuring of benthic foraminiferal assemblages benthic foraminiferal assemblages in contrast to planktic foraminifera generally did not suffer mass extinctions at the cretaceous palaeogene k p boundary extinctions were fewer in deeper water however the outer shelf upper bathyal section at ain settara tunisia records a dramatic change in the structure of benthic foraminiferal assemblages across the k p boundary at the level of extinction of planktic assemblages and enrichment in ir and other geochemical anomalies highly diversified low dominance upper maastrichtian assemblages with infaunal and epifaunal morphogroups were suddenly replaced by taxonomically impoverished assemblages strongly dominated by epifaunal morphogroups this extinction or temporary emigration of most infaunal morphogroups is interpreted to be the result of a sudden breakdown in food supply this in turn is the consequence of a sudden collapse in primary productivity probably resulting from the impact of the k p asteroid

a paleoslope model of campanian to lower maestrichtian foraminifera in the north american basin and adjacent continental margin campanian to early maestrichtian benthic foraminiferal assemblages of the new jersey and delaware coastal plain and the baltimore canyon trough contain distinct bathymetric biofacies each occurring in adjacent settings to one another in a profile downdip toward the north american basin the assemblages are interpreted as representing inner shelf to uppermost middle bathyal environments of deposition 10 to 500 m water depth a unique biofacies which consists of predominantly arenaceous foraminifera in a lithology of dark lignitic shales is present in restricted intervals within the baltimore canyon region this biofacies probably developed under oxygen deficient conditions in middle shelf to upper bathyal paleodepths within the north american basin benthic foraminifers from campanian to lower maestrichtian sections at various dsdp sites indicate that deposition took place in middle bathyal to abyssal environments 500 m to more than 3000 m paleodepth a complete paleoslope profile shelf to abyssal is identified within the north american basin and adjacent continental margin the foraminiferal composition of this paleoslope is as follows gavelinella nelsoni g pinguis lenticulina pseudosecans cibicides harperi andpullenia americana characterize shore face to inner shelf regions of 10 to 50 m water depth species that show maximum development in middle shelf environments 50 to 100 m water depth includeclavulina trilatera hoeglundina supracretacea and nodosariids in the outer shelf 100 200 m water depth praebulimina carseyae gavelinella compressa g spissocostata coryphostoma plaitum andpullenia jarvisi predominate the upper bathyal environment of 200 500 m water depth is characterized by species such asarenobulimina subspherica dorothia oxycona verneuilina dickinsonensis n sp stensioina exculpta gracilis andgyroidinoides globosus pullenia cretacea gavelinella ammonoides g whitei g intermedia praebulimina reussi p cushmani pleurostomella subnodosa andstilostomella pseudoscripta are species common to the middle bathyal environment of 500 to 1500 m water depth species that characterize lower bathyal environments 1500 to 2500 m water depth includearagonia velascoensis reussella szajnochae osangularia utaturensis clavulina gabonica tritaxia aspera andspiroplectammina dentata many of the middle and lower bathyal indicator species extend into the abyssal realm 2500 m water depth where they are associated with more abundant species such asaragonia ouezzanensis reussella pseudospinulosa hyperammina elongata rhizammina indivisa andsaccammina complanata the resulting paleoslope model allows a more critical evaluation of the role played by benthic foraminiferal species in shelf slope and abyssal environments it also enhances the accuracy of estimating paleobathymetry especially in shelf regions of the campanian to early maestrichtian

laboratory observations of rates and patterns of movement of continental margin benthic foraminifera living calcareous and agglutinated benthic foraminifera were collected from a water depth of 220 m on the charleston bump east of charleston south carolina and maintained in aquaria at ambient bottom water temperatures of 12 c and 1 atm in the laboratory the rates and patterns of movement of two species cibicidoides pachyderma rzehak 1886 a calcareous foraminifer and ammodiscus anguillae hoglund 1947 an agglutinated foraminifer are described and compared with published rates of movement for shallow and deep water taxa cibicidoides pachyderma and a anguillae move laterally on a thin veneer of sediment in meandering patterns and both vertically and horizontally in thicker sediments with predominantly straighter patterns in the vertical plane the recorded rates of movement at the substrate surface of c pachyderma and a anguillae vary from 1 0 to 23 and 1 0 to 20 mm day respectively within the sediment 0 5 cm a anguillae moved with a rate varying between 1 0 and 10 mm day these rates are similar to rates for deep sea foraminifera and to the slowest rates of shallow water foraminifera in the laboratory and in the absence of bioturbating organisms both species moved in and out of sediments suggesting that in nature they may be epifaunal and or shallow infaunal taxa

extended period of extinctions across the cretaceous tertiary boundary in planktonic foraminifera of continental shelf sections implications for impact and volcanism theories discussion and reply

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

benthic foraminifera and environmental turnover across the cretaceous paleogene boundary at blake nose odp hole 1049c northwestern atlantic sediments recovered at lower bathyal odp site 1049 on blake nose northwestern atlantic offer an opportunity to study environmental changes at the cretaceous paleogene k p boundary relatively close to the chicxulub impact structure on the yucatan peninsula mexico in hole 1049c the boundary is located at the base of a 9 cm thick layer with abundant spherules considered to be impact ejecta uppermost maastrichtian oozes below and lowermost danian pelagic oozes above the spherulebed contain well preserved bathyal benthic foraminifera the spherule bed itself in contrast contains a mixture of shallow neritic and deeper bathyal species and specimens vary strongly in preservation this assemblage was probably formed by reworking and down slope transport triggered by the k p impact across the spherule bed i e the k p boundary only f7 of benthic foraminiferal species became extinct similar to the low extinction rates of benthic foraminifera worldwide quantitative analysis of benthic foraminiferal assemblages and morphogroups in the 63 am size fraction indicates a relatively eutrophic stable environment during the latest maastrichtian interrupted by a sudden decrease in the food supply to the benthos at the k p boundary and a decrease in diversity of the faunas followed by a stepped recovery during the earliest danian the recovery was probably linked to the gradual recovery of surface dwelling primary producers d 2004 elsevier b v all rights reserved

impact induced mass wasting at the k t boundary blake nose western north atlantic seismic reflection data combined with results from ocean drilling document regional scale slumping associated with the cretaceous tertiary k t impact event the k t boundary is biostratigraphically complete at three ocean drilling program sites 1049 1050 and 1052 located on blake nose 30 n 75 w off eastern florida in water depths of 1300 2600 m maastrichtian chalk is folded and fractured below the k t boundary at all three sites whereas lowermost paleocene clays and chalks are undeformed deformation is pervasive in maastrichtian at the deepest water site site 1049 whereas at the shallower water sites sites 1050 and 1052 thick intervals of structurally intact maastrichtian chalk are separated by thinner intervals of highly deformed sediments correlation of core to seismic reflection data indicates that the k t boundary immediately overlies seismic facies characteristic of mass wasting that extend across most of the 55 km distance of the depth transect maastrichtian sediments appear to have moved as large slump blocks on the upper part of blake nose but deformed more uniformly in the deeper water parts of the transect we suggest that mass wasting occurred on the blake nose 1600 km from the chicxulub crater in response to the cataclysmic seismicity generated by the impact

synchroneity of the k t oceanic mass extinction and meteorite impact blake nose western north atlantic a 10 cm thick layer of green spherules occurs precisely at the biostratigraphic boundary between the cretaceous and paleogene k t boundary at ocean drilling program site 1049 lat 30 08 n long 76 06 w the spherulitic layer contains abundant rock fragments chalk limestone dolomite chert mica books and schist as well as shocked quartz abundant large cretaceous planktic foraminifera and rounded clasts of clay as long as 4 mm interpreted as altered tektite glass probably derived from the chicxulub impact structure most of the cretaceous foraminifera present above the spherule layer are not survivors since small specimens are conspicuously rare compared to large individuals instead the cretaceous taxa in paleocene sediments are thought to be reworked the first paleocene planktic foraminifera and calcareous nannofossil species are recorded immediately above the spherule bed the upper part of which contains an iridium anomaly hence deposition of the impact ejecta exactly coincided with the biostratigraphic k t boundary and demonstrates that the impact event was synchronous with the evolutionary turnover in the oceans these results are consistent with a reanalysis of the biostratigraphy of the k t boundary stratotype which argues that shallow marine k t boundary sections are not biostratigraphically more complete than deep sea k t boundary sites

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

slumping and a sandbar deposit at the cretaceous tertiary boundary in the el tecolote section northeastern mexico an impact induced sediment gravity flow slumps affecting uppermost mendez formation marls as well as the spherulitic layer and basal part of the sandy deposits of the cretaceous tertiary k t boundary clastic unit are described at the new k t el tecolote section northeastern mexico these k t clastic deposits represent sedimentation at middle bathyal water depths in channel and nonchannel or levee areas of reworked materials coming from environments ranging from outer shelf to shallower slope via a unidirectional high to low density turbidite flow we emphasize the development and accretion of a lateral bar in a channel area from a surging low density turbidity current and under a high flow regime the slumps discovered on land and the sedimentary processes of the k t clastic unit reflect destabilization and collapse of the continental margin support the mechanism of gravity flows in the deep sea and represent important and extensive evidence for the impact effects in the gulf of mexico triggered by the chicxulub event