danian selandian boundary stratigraphy paleoenvironment and ostracoda from sidi nasseur tunisia abstract two detailed records nsf and 05nsc sidi nasseur tunisia across the danian selandian d s boundary were investigated for their micropaleontological content calcareous nannofossils and planktic foraminifera provided a biostratigraphic framework the interval spans part of planktic foraminiferal zone p2 subzone p3a and part of subzone p3b this corresponds to calcareous nannoplankton zone np4 using a more detailed nannofossil zonation the studied section spans part of zone ntp6 zone ntp7a and part of ntp7b quantitative ostracod and qualitative benthic foraminiferal data were used to characterize environmental changes across the d s boundary the two subsections have yielded a total of 50 ostracod taxa the ostracod assemblage of the entire section belongs to the southern tethyan type showing subtle but distinct changes up section based on statistical analysis of the quantitative ostracod data faunal changes at a glauconitic maker bed p3a p3b boundary were demonstrated the local reticulina proteros assemblage with the typical species r proteros oertliella vesiculosa and cytheroptheron lekefense is gradually replaced by the protobuntonia nakkadii assemblage with the typical species cristaeleberis arabii xestoleberis tunisiensis cytheropteron sp and p nakkadii across the glauconitic bed the benthic foraminifera also demonstrated distinct changes at this marker bed the changes in ostracods and foraminifera are related to changes in paleoproductivity and an overall relative sea level fall the lithological and faunal changes at the p3a p3b zone boundary within the sidi nasseur sections seem to correspond to the d s boundary in the type region in danmark and are characterized by a significant hiatus yielding this section not suitable as a gssp candidate for this boundary

high resolution image treatment in ichnological core analysis initial steps advances and prospects abstract ichnological studies have become popular during the last decades particularly those associated with the development of two major concepts the ichnofacies model and ichnofabric approach they have driven ichnology into diverse fields of earth sciences including paleoecology sedimentology paleoceanography and basin analysis as well as applied fields for the oil and gas industry and aquifer characterization whereas early ichnological analyses focused on outcrops later the number of ichnological studies on well cores increased noticeably still ichnological research on cores is hampered by certain limitations i e mainly narrow exposed surface and the characterization of ichnological properties is complicated when cores are involved to facilitate ichnological analysis in cores from modern deposits several techniques among them x rays magnetic resonance and computed tomography have been used with the development of computer software a new high resolution image treatment has emerged as a powerful tool in different branches of ichnological studies especially for cores from modern marine deposits because applications are numerous and perhaps not familiar to all the scientific community this paper provides an overview of the usefulness of image treatment in ichnological analysis its first steps and subsequent development the novel techniques most recently used in the study of cores from modern marine deposits and some challenges for future research

trace fossils biology and taphonomy 1990 special topics in palaeontology 3 280 pp e17 95 pbk e40 00 hbk unwin hyman london isbn 004445 6867 pbk 3035 hbk

paleocene sea level and productivity changes at the southern tethyan margin el kef tunisia integrated analysis of quantitative distribution patterns of organic walled dinoflagellate cysts dinocysts and benthic foraminifera from the paleocene el kef section nw tunisia allows the reconstruction of sea level and productivity fluctuations our records indicate that the environment evolved from an initially oligotrophic open marine outer neritic to upper bathyal setting towards a more eutrophic inner neritic setting influenced by coastal upwelling by the end of the paleocene an overall second order change in paleodepth is reflected by both microfossil groups from the base of planktic foraminifera zone p4 onwards the main phase of shallowing is evidenced by an increase of inner neritic dinocysts of the areoligera group disappearance of deeper water benthic foraminifera and increasing dominance of shallow marine taxa several buliminids haplophragmoides spp trochammina spp the total magnitude of this shallowing is obscured by interaction with a signal of eutrophication but estimated to be around 150 m from 200 to 50 m superimposed on the overall trend third order sea level fluctuations have been identified and correlated to sequences in other regions paleoproductivity indicators notably protoperidinioid dinocysts and buliminids show a trend from an oligotrophic to a eutrophic setting d 2005 elsevier b v all rights reserved

trace fossils after the k t boundary event from the agost section se spain palaeogene trace fossils penetrate the uppermost cretaceous sediments in the agost section betic cordillera se spain chondrites targionii zoophycos isp planolites isp a planolites isp b thalassinoides isp a thalassinoides isp b thalassinoides isp c alcyonidiopsis longobardiae and diplocraterion parallelum have been identified a well developed endobenthic tiering pattern is interpreted the uppermost tier a represents major benthic activity in the shallowest sediments at or just below the seafloor recorded as bioturbated background only discrete rare planolites the next upper tier b displays the highest trace fossil diversity with planolites in the shallow levels and thalassinoides and alcyonidiopsis at slightly deeper ones the intermediate tier c contains randomly distributed thalassinoides and alcyonidiopsis cross cut by zoophycos and large and medium sized chondrites the deepest tier d contains zoophycos cross cut by medium and mainly small sized chondrites two interpretations are proposed 1 vertical partitioning of a singled multi tiered community under steady stable conditions in well oxygenated water bottom reflecting gradual changes deep into the sediment with decreasing oxygen pore water and benthic food and increasing substrate consistency and 2 sequential colonization and community replacement reflecting the work of two successive communities the first community mainly represented by planolites alcyonidiopsis and thalassinoides was produced in a shallow oxygenated soft substrate probably related to decreasing oxygen content and benthic food availability this community was replaced by deeply burrowing organisms that produced zoophycos and chondrites this sequential colonization can be determined by changes in environmental parameters related to the cretaceous palaeogene k t event or may have resulted from normal ecological and early diagenetic processes

palaeo mixing zone karst features from palaeocene carbonates of north spain criteria for recognizing a potentially widespread but rarely documented diagenetic system abstract marine meteoric mixing zone dissolution effects are a major feature of present day karst systems in carbonate platforms yet are rarely reported in the geological record an example is described from the upper danian platform limestones of the alava province in the western pyrenees north spain this consists of several narrow zones with sponge like porosity analogous to the swiss cheese features found in present day mixing zones these zones are stained by fe oxides and overlie limestones which are irregularly dolomitized and contain disseminated pyrite these high porosity zones are interpreted as having developed in marine mixing zones where mixing corrosion and microbially mediated processes increased dissolution if collapsed ancient mixing zones could be misinterpreted as terra rossa palaeosols the main criteria to identify them as mixing zone products are their occurrence below a palaeo meteoric phreatic zone their association with stratified oxic and anoxic redox zones and petrographic evidence for highly variable calcite saturation states

ichnological record of deep sea palaeoenvironmental changes around the oceanic anoxic event 2 cenomanian turonian boundary an example from the barnasiowka section polish outer carpathians abstract trace fossil assemblages including planolites thalassinoides palaeophycus taenidium chondrites and trichichnus have been determined in the upper cenomanian turbiditic deep water succession corresponding to the pre oae 2 interval in the barnasiowka ostra gora section the skole nappe polish outer carpathians these assemblages indicate that oxygenation within sediment fluctuated from oxic to dysoxic zone the overlying uppermost cenomanian organic rich facies bonarelli equivalent horizon corresponding to the main interval of the oae 2 contains black shale layers devoid of trace fossils representing anoxic euxinic events and green shales that include chondrites planolites and thalassinoides recording dysoxic intervals three subintervals phases within the oae 2 sediments have been distinguished in the barnasiowka section based on trace fossil diversity ichnofabrics and chemical redox indices these phases correspond to intervals with various intensity of sea floor oxygenation ichnofabrics within the oae 2 succession was also controlled by consistency of sediment post oae 2 interval recorded by the earliest turonian red and green siliceous manganiferous shales and two fe mn layers represent sediments deposited in well oxygenated conditions under extremely low sedimentation rate most of the shales are parallel laminated and they do not include any benthic microfossils and trace fossils however some of the red and green layers display cryptic bioturbation these features are related to food scarcity cessation of gravity flows unfavorable characteristics of bottom water and a low consistency of substrate

impact of the paleocene eocene thermal maximum on the macrobenthic community ichnological record from the zumaia section northern spain article i nfo trace fossil assemblages from the latest paleocene to the earliest eocene were significantly affected by the environmental perturbation of the paleocene eocene thermal maximum petm high resolution ichnolo gical analysis shows well marked different ichnological features pre syn and post event a well developed normal tiered burrowing community is present in the sediments below the petm indicating oxic conditions and normal benthic food availability during the petm the record of trace fossil producers disappeared gradually but rapidly reflecting the global increase in temperature and the concentration of benthic food in the very shallow surface layer and probably the local depletion of oxygen within the sediments although probably not true anoxia the environmental perturbation significantly affected the whole benthic habitat as shown by the correspondence with the main phase of the benthic foraminiferal extinction after the petm the normal tiered burrowing community recovered gradually and slowly in a delayed return to pre petm environmental conditions the changes in the trace fossil assemblage thus document the impact of the petm on the macrobenthic community a decline in oxygen levels during the petm in a globally perturbed habitat due to global warming and the similarities and differences in the response of micro and macrobenthic communities to global phenomena thus ichnological analysis reveals as a very useful additional tool to understanding atmosphere ocean dynamic during petm and a potential way in future climate research 2011 elsevier b v all rights reserved

sea level dynamics and palaeoecological factors affecting trace fossil distribution in eocene turbiditic deposits gorrondatxe section n spain abstract ichnological analysis of the upper ypresian lower lutetian interval at the gorrondatxe section w pyrenees n spain reveals a relationship between sea level dynamics and the eco sedimentary factors influencing trace fossil assemblages the 600 m thick section of deep sea turbiditic deposits contains 41 ichnospecies belonging to 28 ichnogenera which are typical of the nereites ichnofacies and mostly of the paleodictyon ichnosubfacies suggesting deposition in a basin plain to fan fringe setting the trace fossil diversity and abundance fluctuate irrespective of turbidite frequency these ichnological features are strongly affected by trophic level changes related partly to sea level dynamics according to the sequence stratigraphic interpretations for the studied section temperature oxygenation and substrate changes are also considered as relevant factors increased ichnodiversity particularly among graphoglyptids coincides with moderate oligotrophy and stable ecological conditions eutrophisation lowered oxygenation and drop of temperature typical of low sea level can reduce ichnodiversity

covarying sedimentary and biotic fluctuations in lower middle eocene pyrenean deep sea deposits palaeoenvironmental implications abstract analyses of expanded 1975 to 3330 m thick deep marine ypresian lutetian successions from the pamplona and basque basins w pyrenees demonstrate a recurring pattern of coeval sedimentary and biotic changes intervals rich in resedimented deposits are typified by high latitude planktonic foraminiferal indices whereas intervals devoid of large scale resedimented deposits megabreccias are characterized by low latitude planktonic foraminiferal indices data from the megabreccia free intervals record a reasonably good correlation between the vertical trend of planktonic foraminiferal indices from the two pyrenean basins and the global curve of oxygen isotopes from deep sea records for instance the early eocene climatic optimum and the long lasting late ypresian lutetian cooling are respectively recorded in the studied successions by an increase and by a progressive decline in abundance in low latitude planktonic foraminiferal indices this correlation may support the assumption that changes of planktonic foraminiferal indices in the megabreccia free intervals were forced by global climatic changes the dominance of high latitude planktonic foraminiferal indices in the megabreccia bearing intervals is more difficult to interpret such dominance might record global cooling episodes that resulted in eustatic lowstand resedimentation events however the climatic cooling and sea level fall do not fully explain the characteristics of these intervals a reasonable scenario is that tectonically induced resedimentation processes resuspended large volumes of mud and organic matter which led to the eutrophication of seawater such eutrophication would preferentially affect low latitude oligotrophic planktonic foraminiferal species and lead to a relative or absolute increase in the cosmopolitan opportunistic species that typify high latitude groups

paleocene coralgal reefs of the western pyrenean basin northern spain new evidence supporting an earliest paleogene recovery of reefal ecosystems abstract the rate of recovery of photic reefal ecosystems after the cretaceous tertiary crisis is controversial most reports from earlier authors concluded that paleogene reef systems did not completely recover from that crisis at least until oligocene miocene times several other authors however have pointed out that such conclusion was biased by poor preservation and or inaccessibility of many early paleogene successions and that the recovery of reefs might have been a faster process the latter possibility is here strongly supported with data from the pyrenean basin where paleocene shallow water carbonate deposits are thickly developed and outcrop widely five growth phases of reef development have been recognized and age dated with calcareous nannofossils which together define a complete sequence of expansion reduction of reef ecosystems during the paleocene epoch reef growth phase 1 early danian lower middle np3 calcareous nannofossil zone the initial step of that sequence demonstrates that coral dominated reef systems came back into existence less than 2 ma after the k t boundary a comparatively short time considering the magnitude of the end cretaceous biological crisis the climax of the sequence is recorded by growth phase 3 late danian np4 zone when a thick barrier reef complex was developed which was at least 200 km in length but probably much larger and made up by a well diversified coralgal assemblage reef growth phases 4 and 5 early and middle thanetian np6 to np8 zones were characterized by low relief reef banks dominated by encrusting calcareous algae and had less well diversified coral assemblages features that point to a deterioration of environmental conditions tentatively interpreted in terms of a climatic cooling reef bioconstruction almost disappeared in the pyrenean basin during late thanetian times although in all likelihood this is a regional effect of no evolutionary relevance the new data suggest that the cenozoic recovery of reefs was rapid but punctuated with a phase of important reef expansion already in the late danian

untangling the palaeocene climatic rhythm an astronomically calibrated early palaeocene magnetostratigraphy and biostratigraphy at zumaia basque basin northern spain abstract the magnetostratigraphy of a 54 m long section above the cretaceous tertiary boundary at the sea cliff section of zumaia in the basque basin northern spain has been established the section encompasses the entire danian and the lower part of the selandian stages as indicated by calcareous plankton biostratigraphy the studied interval consists of hemi pelagic limestone marl alternations in the form of couplets and bundles which range from centimetre decimetre to metre scale respectively and a few thin bedded calcareous turbidites the magnetostratigraphy based on samples from about 200 stratigraphic levels allows the identification of six reversal boundaries from chron c29r to c26r at a bed level the spatial or temporal evolution of periodicities from a lithologically coded series is studied with the continuous wavelet transform technique a preliminary age model based on the standard ck95 gpts indicates that the basic lithologic carbonate marl couplet corresponds to the 19 23 kyr precession cycle 21 31 cm cycle in the depth domain and that a bundle cycle usually groups of four to six basic couplets with global periodicity centred at 1 22 m corresponds to the 110 kyr eccentricity cycle we have tuned the bundle cycles to the va03 r7 eccentricity orbital solution astrophys j 592 2003 620 630 following an initial match of a node of the 2 4 ma eccentricity modulatory cycle in the target time series to particularly carbonate rich bundles from the upper part of the zumaia section that displays significant power of a 4 4 m period cycle corresponding to the 404 kyr eccentricity cycle consistency between lithologic patterns and characteristics in the eccentricity target is reasonably met although the 404 kyr eccentricity cycle is not persistent throughout the tuning however appears robust as it brings the age of the k t boundary at 65 8 ma it is argued that a sea level signal tectonically driven is superimposed on the climatic forcing at the milankovitch band masking the full expression of the low frequency astronomical periods we provide a cycle tuned duration for all intervening early palaeocene polarity chrons and estimate relative ages for bioevents the cycle tuned chronology indicates that the ck95 gpts overestimates the duration of chrons c28 and c27 by 20 and 26 respectively our data may prove useful to better constrain early palaeocene biostratigraphy of calcareous plankton and in the redefinition of the boundary between the danian and selandian stages

use of high resolution ichnological and stable isotope data for assessing completeness of a k p boundary section agost spain high resolution ichnological analysis has been performed at the agost section betic cordillera southeast spain in order to assess the completeness of the k p boundary transition below the biostratigraphic resolution intrasubzone high resolution planktonic foraminifera biozonation revealed that the first appearance of the palaeogene index species does not coincide with the k p boundary but is located a few centimetres above and calibrated 65 7 6 7 ky later the k p boundary to establish the continuity of this first interval of the lowermost danian hedbergella holmdelensis subzone and the existence of any hiatus below biostratigraphic resolution trace fossil analysis was revealed to be a useful tool planolites thalassinoides and alcyonidiopsis structures belonging to the upper tiers colonizing at or immediately after the k p boundary event were studied focusing on the isotopic composition of the filling materials and the genesis of thalassinoides rapid firmground generation and thalassinoides tracemaker colonization is mainly attributed to cessation of precipitation and or deposition of calcium carbonate but an incipient lithification is not disregarded the d 13 c data obtained from trace fossils fit well with those corresponding to a the k p boundary layer from 1 00x to 1 30x b the stratigraphic interval between 2 5 and 5 0 cm above the k p boundary between 0 32x and 0 47x and c the interval between 7 0 and 11 0 cm above the k p boundary between 0 69x and 0 79x revealing continuity in the colonization from the k p boundary event to the dark clay deposition above this macrobenthic colonization occurred continuously during the dark layer deposition from the k p boundary layer including the first centimetres evidencing completeness and the absence of hiatuses below biostratigraphic resolution intrasubzone at the agost section d 2005 elsevier b v all rights reserved

closing the mid palaeocene gap toward a complete astronomically tuned palaeocene epoch and selandian and thanetian gssps at zumaia basque basin w pyrenees abstract an integrated magneto bio and cyclostratigraphic framework is presented for the mid palaeocene interval from the hemi pelagic sea cliff section of zumaia in the basque basin the new 55 m long studied section expands about 3 5 myr and closes the gap between previously published integrated studies in the section the occurrence of magnetochron c26n is now documented and its duration complemented also by data from the ibaeta section and that for chrons c26r and c25r is estimated by counting precession related lithologic couplets assigned to have 21 kyr duration c25r 1449 kyr c26n 231 kyr c26r 2877 kyr consequently the zumaia section now provides the first complete palaeocene astronomically derived chronology rendering this section a master reference section due to limitations in the orbital calculations and uncertainties in the radiometric dating method no robust tuning and absolute ages can be given for the moment however the fos first occurrences of key calcareous plankton species and the mid palaeocene biotic event mpbe are placed within the magnetostratigraphic and cyclostratigraphic template along the studied mid palaeocene interval in addition the dataset provides the key elements for a proper settling of the thanetian and selandian global stratotype section and point gssps which is one of the primary objectives of the ics international commission of stratigraphy we consider the base of chron c26n and the criteria associated to the lithostratigraphic change between the danian limestone fm and the itzurun marl fm at zumaia as the respective delimiting points for the thanetian and selandian bases as recently agreed by the paleocene working group of the international subcommission of the paleogene stratigraphy of the ics consequently the duration of the thanetian selandian and danian component stages can be estimated at zumaia to be about 3129 kyr 2163 kyr and 4324 kyr respectively see text for error considerations however the mpbe located 8 precession cycles below the base of c26n in correspondence to a short eccentricity maxima at zumaia could also serve as a guiding criteria to approximate or redefine the thanetian base if this level demonstrated synchronous

nutrient spatial variation during intrabasinal upwelling at the cenomanian turonian oceanic anoxic event in the westernmost tethys an ichnological and facies approach abstract facies and ichnofabrics of two sections of the cenomanian turonian boundary interval are correlated and compared to evaluate changes in palaeoceanographic conditions controlled by palaeogeography in the distal zone of the westernmost tethys southern iberian continental palaeomargin the oceanic anoxic event oae 2 was interrupted by short aerobic or dysaerobic sub events with slight differences in facies and ichnofabrics these sub events display a tendency to expansion from the more distal section hedionda towards the proximal one el chorro the anoxia spread out from the open sea probably from slope upwellings higher diversity and abundance of trace fossils in comparatively distal position during the pre and post event intervals can be caused by a higher abundance of food available for tracemakers shape of the correlation bands of the oae 2 event suggests that the event started earlier by about a few tens of thousands years in the most distal areas than in proximal slightly higher bottom settings

the palaeocene top chron c27n transient greenhouse episode evidence from marine pelagic atlantic and peri tethyan sections terra nova 24 477 486 2012 abstract the early cenozoic which is punctuated by several negative carbon isotope excursions cies was a time of climatic and oceanographic transition from greenhouse to icehouse conditions the occurrence of a 0 5 cie starting at the top of chron c27n tc27n is reconfirmed with stable isotope data from zumaia spain and bjala bulgaria localities spectral analysis on respective carbonate magnetic susceptibility proxy records substantiates the orbital cyclostratigraphy allowing correlation to a high resolution benthic foraminifera isotope record from odp pacific site 1209 that indicates a coeval 2 c transient warming the hyperthermal event lasts 200 ka contrasting with other short lived events from the eocene and displays a relatively rapid onset and a longer tailing back to pre event values similar to the palaeocene eocene thermal maximum petm though lower in amplitude that a causal trigger for the tc27n event may be the onset of volcanism in the north atlantic igneous province naip can be inferred from a 200 m thick lava pile erupted during c27n c26r polarity transition in the e greenland margin

paleoenvironmental change at the danian selandian transition in tunisia foraminifera organic walled dinoflagellate cyst and calcareous nannofossil records abstract in the present study we document paleoenvironmental change across the danian selandian transition planktic foraminiferal interval p2 p3b calcareous nannofossil zone np4 subzones ntp6 ntp8a 61 59 ma in nw tunisia diversifications of paleogene planktic foraminifera with the evolution of the muricate and photosymbiotic lineages morozovella acarinina and igorina and of the biostratigraphically important nannofossils genus fasciculithus are recorded within this interval the present study aims to understand early paleogene environmental changes in the southern tethys by analyzing the evolution of surface water and to a lesser extent seafloor conditions three localities were investigated ain settara elles and el kef all representing outer neritic deposition in the same basin the tunisian trough paleoenvironmental changes are explored by combining planktic foraminiferal organic dinocyst and calcareous nannofossils assemblages and several proxy parameters planktic benthic ratio numbers of planktic foraminifera per gram peridinioid gonyaulacoid ratio terrestrial marine palynomorph ratio in addition also some geochemical parameters calcite content and stable isotopes are examined our records indicate that the environment evolved from an initially oligotrophic open marine deep outer neritic setting in p2 p3a towards a shallower and nutrient rich setting from the base of subzone p3b this change is seen in the foraminiferal assemblages with the substitution of praemurica by morozovella among the planktic foraminifera and an upward decrease in deeper benthic taxa also the organic dinocyst assemblages show a peak of peridinioid cysts cerodinium and lejeunecysta associated to these dinocyst assemblages the lowest occurrence of apectodinium is recorded which seem to have evolved in this region possibly in response to enhanced nutrient levels on the shelf additionally a distinct change in calcareous nannofossil assemblages is also described marked by the lowest appearance of chiasmolithus edentulus the lowest consistent occurrence of fasciculithus and a slight increase in near shore taxa essentially pontosphaera this project provides an accurate understanding of paleoenvironmental change across the danian selandian transition in tunisia especially integrating different proxies demonstrates a paleobathymetric shallowing from the danian to the selandian associated to increase surface paleoproductivity furthermore the results are compared with those from other localities along the southern tethyan margin egypt and jordan and a more regional paleoclimatic paleoceanographic perturbation in the southern tethys is suggested

a complete high resolution paleocene benthic stable isotope record for the central pacific odp site 1209 1 we have compiled the first stratigraphically continuous high resolution benthic foraminiferal stable isotope record for the paleocene from a single site utilizing cores recovered at pacific odp site 1209 the long term trend in the benthic isotope record suggests a close coupling of volcanic co2 input and deep sea warming over the short term the record is characterized by slow excursions with a pronounced periodic beat related to the short 100 kyr and long 405 kyr eccentricity cycle the phase relationship between the benthic isotope record and eccentricity is similar to patterns documented for the oligocene and miocene confirming the role of orbital forcing as the pace maker for paleoclimatic variability on milankovitch time scales in addition the record documents an unusual transient warming of 2 c coeval with a 0 6 carbon isotope excursion and a decrease in carbonate content at 61 75 ma this event which bears some resemblance to eocene hyperthermals marks the onset of a long term decline in 13c the timing indicates it might be related to the initiation of volcanism along greenland margin

danian selandian boundary criteria and north sea basin tethys correlations based on calcareous nannofossil and foraminiferal trends in sw france abstract high resolution calcareous nannofossil and foraminiferal investigations of the bidart and loubieng outcrop sections allow to define a time calibrated sequence of 47 bio events within the danian selandian d s boundary interval 61 2 59 7 ma of aquitaine sw france the d s boundary as originally defined in denmark start of clastic sedimentation at the base of the lellinge greensand formation is marked by the end of the acme of the nannofossil family braarudosphaeraceae this bio event dated at 59 9 ma has also been identified at the lithological change from limestone dominated lasseube formation to marly sedimentation latapy member of the pont labau formation in sw aquitaine and at the base of the red marls of the itzurun formation at zumaia spain recently designated as global stratotype section and point gssp for the d s boundary this implies contemporaneity of this lithological shift throughout europe and a gssp proposal which is consistent with the original boundary definition the braarudusphaeraceae event is believed to be due to the interruption of freshwater influx probably related to a sudden decrease in precipitation it is located at the top of nannofossil zone np4 and within planktonic foraminiferal zone p3b and bracketed between the lowest occurrence lo of morozovella velascoensis below and the lo of fasciculithus tympaniformis above it is coincident with the lo of bomolithus elegans the lcso cs consistent of fasciculithus janii and the lo of subbotina velascoensis the d s boundary as originally defined is 400 k y posterior to a major discontinuity recorded throughout the tethyan realm tunisia egypt and up to now erroneously considered to correspond to the d s boundary this break in sedimentation dated at 60 3 ma and coinciding with the p3a p3b boundary is due to a major sea level fall it is correlated with sedimentation changes in the aquitaine zumaia area start of development of marly interbeds and in the north sea basin transition bryozoan limestone calcisiltite in denmark transition shallow marine mons formation continental hainin formation in belgium the loubieng section supplements the zumaia section because of its rich and well preserved fossil content and continuous sedimentation it constitutes an excellent auxiliary section for the d s boundary

palaeoenvironmental changes across the danian selandian boundary in the north sea basin abstract the danian selandian boundary 60 ma marks the cessation of 40 million years of carbonate deposition in the north sea basin and a shift to siliciclastic deposition on the basis of variations in lithology benthic and planktonic foraminifera and calcareous nannofossils in three cores from storebaelt in the eastern part of the north sea basin we have reconstructed the palaeoenvironmental changes across the boundary the benthic foraminiferal faunas belong to the midway type fauna they are extremely rich and more than 260 taxa have been recognized q mode cluster analysis groups the benthic assemblages into four biofacies which correspond fairly closely to lithological units correlation of the storebaelt records with marine palaeorecords from the danish basin and the north sea basin indicate that the transformation of the north sea from a carbonate to a siliciclastic basin occurred in four steps separated by relatively long stable periods the most important external factors involved in the change are firstly a drop in the relative sea level during the late danian leading to the disappearance of bryozoans from the north sea basin and to non deposition and erosion in many areas secondly coinciding with the danian selandian boundary an uplift of the scotland shetland area resulting in a massive input of siliciclastic deposits to the north sea basin thirdly during the early selandian inversion of the sorgenfrei tornquist zone and mesozoic basins in the southern and eastern part of the north sea basin resulted in a huge influx of reworked cretaceous chalk and an almost complete stop of carbonate production finally later in the early selandian in connection to a general sea level rise and a reduction in the gateway between the north sea basin and the tethys sea the sea bottom conditions became colder and more acidic this resulted in partial dissolution of the carbonates and the deposition shifted from marl to clay comparison with records from the western pyrenees the nile basin and the eastern north america suggests that sea level changes across the danian selandian boundary are primarily of eustatic nature

fe oxide spherules infilling thalassinoides burrows at the cretaceous paleogene k p boundary evidence of a near contemporaneous macrobenthic colonization during the k p event a detailed ichnological analysis focused on thalassinoides structures recorded just below the cretaceous paleogene k p boundary layer of the agost section southeast spain aimed to evaluate macrobenthic colonization during the k p boundary event stereomicroscopy and field emission scanning electron microscopy analyses conducted on material filling in thalassinoides trace fossils reveal the presence of dark infill material that includes spherule like elements similar to those previously differentiated in the k p boundary layer energy dispersive x ray spectrometry indicates a ferruginous composition goethite spherules this represents the first record of spherules related to the k p boundary event within trace fossil infilling material the passive filling of this material into the thalassinoides bioturbation allows interpretation of the gravitational deposition just after thalassinoides trace maker colonization the absence of erosive sedimentary structures or other material deposited between the thalassinoides trace maker colonization and the spherule deposition is interpreted as evidence of rapid colonization during the k p boundary event nearly contemporary with the spherule layer deposition

palaeohydrogeological control of palaeokarst macro porosity genesis during a major sea level lowstand danian of the urbasa andia plateau navarra north spain abstract an extensive palaeokarst porosity system developed during a pronounced mid paleocene third order lowstand of sea level is hosted in danian limestones of the urbasa andia plateau in north spain these limestones were deposited on a 40 50 km wide rimmed shelf with a margin characterised by coralgal buildups and coarse grained bioclastic accumulations the sea level fall that caused karstification was of approximately 80 90 m magnitude and 2 5 ma in duration during the exposure a 450 m wide belt of sub vertical margin parallel fractures developed a few hundred metres inboard of the shelf edge most fractures are 90 100 m deep average 1 m in width and are associated with large erosional features created by collapse of the reefal margin inland from the fracture belt three superimposed laterally extensive cave systems were formed over a distance of 3 5 km perpendicular to shelf edge at depths ranging from 8 31 m below the exposure surface the palaeocaves range from 0 3 to 2 m in height average 1 5 m high they show no evidence of meteoric processes and are filled with thanetian grainstones rich in reworked microcodium a lithology that also occurs infilling the fractures the caves are interpreted as due to active corrosion at the saline water fresh water mixing zone caves are missing from the shelf edge zone probably because the fractures beheaded the meteoroic lens preventing mixing zone cave development beyond the fracture zone towards the platform interior each cave system passes into a prominent horizon averaging 1 m in thickness of spongy porosity with crystal silt infills and red fe oxide coatings the spongy horizons can be traced for 5 5 km inboard from the cave zone and occur at 10 5 m 25 m and 32 m below the exposure surface in the inland zone two additional horizons with the same spongy dissolution have been recognised at depths of 50 m and 95 m all are analogous to swiss cheese mixing zone corrosion in modern carbonate aquifers and probably owe their origins to microbially mediated dissolution effects associated with a zone of reduced circulation in marine phreatic water in the most landward sections a number of collapse breccia zones are identified but their origin is unclear the palaeokarst system as a whole formed during the pulsed rise that followed the initial sea level drop with the three main cave spongy zones representing three successive sea level stillstands recorded by stacked parasequences infilling large erosional scallops along the shelf margin the geometry of the palaeo mixing zones indicates a low discharge system and together with the lack of meteoric karstic features favours a semi arid to arid climatic regime which is further supported by extensive calcrete bearing palaeosols occurring in coeval continental deposits

carbon isotope evidence for the timing of the cretaceous palaeogene macrobenthic colonisation at the agost section southeast spain abstract the cretaceous palaeogene k t boundary section of agost southeast spain one of the most complete sections existing contains a well developed trace fossil assemblage composed of dark and light filled trace fossils registered in the uppermost cretaceous maastrichtian plummerita hantkeninoides biozone sediments the trace fossil assemblage reveals that significant macrobenthic colonisation occurred around the k t boundary interval however difficulties in recognising trace fossils affecting the k t boundary layer as well as in biostratigraphically characterising these trace fossils hindered a conclusive interpretation on the timing of this macrobenthic colonisation with the aim of this characterisation we determined the 13c of the carbonate fraction of dark and light filling materials from the trace fossils since the carbon isotope compositions of uppermost cretaceous and lowermost palaeogene materials are clearly different the data compiled provide evidence for a significant distinction between light filled trace fossils with 13c values higher than 1 6 peedee belemnite pdb and dark filled trace fossils with 13c values between 0 21 and 1 2 pdb most of these being lower than 0 7 pdb the comparison of these values with those from the uppermost maastrichtian to the lowermost danian sediments reveals that the macrobenthic colonisation occurred in different phases across the k t boundary interval

latest cretaceous paleocene deep sea ostracode fauna at iodp site u1407 western north atlantic with special reference to the cretaceous paleogene boundary and the latest danian event abstract during the paleocene the marine plankton community recovered its diversity after a severe diversity loss at the cretaceous paleogene k pg boundary in general changes in paleocene deep sea ostracode faunas are poorly understood it is still unclear how the deep sea ostracode faunas changed during compelling events such as the k pg boundary 66 04 ma and the latest danian event lde 62 18 ma a transient paleocene warming event in this report we describe a study on the latest cretaceous late paleocene ostracodes from integrated ocean drilling program site u1407 off newfoundland in the northwestern atlantic thirty six ostracode taxa were obtained from 202 discrete samples that were collected from the interval between 66 3 and 57 3 ma near the k pg boundary 8 2 of 25 of the maastrichtian taxa became extinct the extinction rate is estimated to be at most 0 12 e msy 1 which is equal to extinction rate of 12 per one million years and is in the same range as the background level extinction rate comparing the extinction rates between different ocean basins such as maud rise and blake nose the ostracode extinction at the k pg boundary displays striking geographical heterogeneity between the maastrichtian and danian the ostracode faunas change from a biofacies dominated by shallow bathyal taxa to one dominated by deep bathyal taxa during the lde ostracode faunas display an increase in their benthic ostracode accumulation rates and taxonomic diversity as well as an increase in the relative abundance of krithe crassicaudata simultaneously with a decline in carbonate content a similar change is commonly documented in fauna from the northeastern atlantic during the paleocene eocene thermal maximum petm 56 0 ma in contrast to the petm fauna an extinction event is not recognized near the danian selandian boundary the ostracodes show an increase in export productivity after the danian the ostracodes form a community that appears to tolerate warm and acidified water export productivity remains high during the selandian and thanetian

characterization of the latest danian event by means of benthic foraminiferal assemblages along a depth transect at the southern tethyan margin nile basin egypt abstract the latest danian event lde has been recognized on the southern tethyan margin egypt tunisia and in the atlantic zumaia spain and pacific oceans odp site 1209 based on a supraregional carbon isotope excursion and a negative shift in oxygen isotopes in the pacific it has been suggested that the lde is an early paleogene transient warming event so far the environmental effects of the lde have been observed in few sections and details on its impact and duration are scarce we present a quantitative study of benthic foraminiferal assemblages retrieved from five sections along a depth transect on the paleocene southern tethyan shelf nile basin egypt to assess paleoenvironmental change during the lde the lithologic sequences and foraminiferal assemblages indicate that the onset of the lde is related to widespread shelf dysoxia the organic rich laminated marls of lower lde bed i contain levels devoid of benthic foraminifera during the later stage of the lde dark gray shales of bed ii the shelf is repopulated by a neoeponides duwi benthic assemblage occurring in all sections initiating a gradual restoration of normal marine shelf environments q mode and r mode correspondence analysis assist in the interpretation of the n duwi assemblage which is related to disturbed conditions at the sea floor following oxygen depletion and increased organic loading the sharp lithologic boundary at the base of the lde suggests that the event coincides with a rapid transgression following a sea level fall with an estimated amplitude of 50 m or less comparison with the dan c2 and elpe mpbe two proposed transient warming episodes preceding and postdating the lde shows that the three paleocene events have several characteristics in common however the duration of the lde 200 kyr exceeds the estimated duration of the other events and a sea level cycle is only reported from the lde

ichnological analysis of the cretaceous palaeogene boundary interval at the caravaca section se spain abstract ichnological analysis of the cretaceous palaeogene k pg boundary at caravaca betic cordillera southeast spain reveals significant data for the interpretation of the k pg boundary event the uppermost maastrichtian marls below the cretaceous palaeogene k pg boundary at caravaca contains the dark coloured trace fossils chondrites targionii planolites thalassinoides zoophycos and alcyonidiopsis the composition of trace fossil associations in the upper maastrichtian and lower danian marls is generally the same yet much more poorly preserved in the latter showing in general no ichnological evidence of a severe macroinfaunal crisis at the k pg boundary the dark coloured trace fossils penetrate from two bioturbated horizons in the dark boundary layer separated by two horizons with primary lamination the ichnofauna rapidly recovered after the k pg event following deposition of the lower parallel laminated bed 14 mm thick that occurs in the dark boundary layer above the k pg boundary zoophycos is the deepest trace fossil penetrating as far as 90 cm below the k pg boundary probably in stiff or partly firm substrate which was dewatered to some extent during the slow accumulation of the danian dark boundary layer the firmness probably prevented the chondrites trace maker from deeper burrowing the maastrichtian sediments may be contaminated with danian microfossils due to bioturbation

a nomogram for interpreting slope stability of fine grained deposits in modern and ancient marine environments abstract a nomogram has been constructed for analyzing slope stability in fine grained sedimentary environments it was designed to aid in interpreting the muses of mass movement in modern and ancient settings to provide a basis for evaluating and predicting slope stability under given conditions and to further the understanding of the relationships among the several key factors that control slope stability design of the nomogram is based on effective stress and combines consolidation theory as applicable to depositional environments with the infinite slope model of slope stability analysis the link between the two combined theories is a term representing the effective overburden stress which may be predicted from consolidation theory and a knowledge of sedimentation rate time and the coefficient of consolidation in turn if infinite slope conditions are assumed to exist the effective overburden stress can be used to derive a factor of safety against static slope failure by using the angle of internal friction and the slope angle values of the variables may be determined directly from measurement or depending on the objectives or limitations of the application they may be speci ied or estimated information supplied with the nomogram is intended to assist in estimating values where necessary the nomogram applies to depositional settings in which fine grained sediment has accumulated at a relatively constant rate upon a base that is essentially impermeable the model further assumes that the lateral extent of sediment affected by any mass movement will be great compared to its thickness and that no outside agents e g cements gas are influencing the section the nomogram is applicable to static conditions inherent stability of the slope and certain dynamic conditions such as earthquakes it may be used to investigate mass movements in the geologic past as well as those in modern environments although the nomogram was not designed to be more than an interpretive aid and was not intended for solving slope stability problems of any complexity or where precision is required it does provide a basis for interpretation and an adequate first approximation in most cases

late cretaceous to late eocene palaeogeographic evolution of southwest europe abstract a synthesis of personal research concerning the peri pyrenean region and previously published data is presented as a series of palaeogeographic reconstructions subsequent to the progressive regression at the end of the cretaceous the sea invaded three times parts of the earlier senonian marine domain on both sides of the eastern palaeo pyrenees pre cuisian climatic rewarming combined with cuisian continental epeirogenic deformations resulted in major biogeographic modifications during the cuisian local tectonics forced the sea from the northern pyrenean basin whereas in the southern pyrenean basin the sea retreated much later as a consequence of the pyrenean tectonic phase however the pyrenean tectogenesis seems to have affected a much larger region including the alps shoreline migrations are compared and related to the geodynamic behaviour of the meridional and septentrional european provinces in order to distinguish between tectonic and eustatic causes

high resolution intra and interbasinal correlation of the danian selandian transition early paleocene the bjala section bulgaria and the selandian gssp at zumaia spain abstract the danian selandian d s boundary has been identified for the first time in the black sea coast at bjala bulgaria based on a new integrated bio magneto and cyclostratigraphic study several correlation criteria as established for the basal selandian gssp from zumaia basque basin are evaluated noteworthy is the almost complete lack of calcareous nannoplankton species braarudosphaera bigelowi in the bulgarian sections a sharp decrease of which was indicated as suitable criteria for defining the d s boundary as it occurred both at zumaia and in the classical locations of the north sea basin conversely the second evolutionary radiation of the calcareous nannofossil genus fasciculithus together with the occurrence of fasciculithus tympaniformis that define the np4 np5 zonal boundary seem to be reliable criteria to approximate the d s boundary in detail however the best approach is to integrate biostratigraphic data within a magnetostratigraphic and or cyclostratigraphic framework refinements on the placement of chron c27n at zumaia and robust bed by bed correlation between several basque sections and bjala indicates that the d s boundary is located 30 precession cycles 630 ky above c27n in addition to the precession related marl limestone couplets and 100 ky eccentricity bundles recognized in the studied sections expression of the stable 405 ky long eccentricity allows direct tuning to the astronomical solutions a correlation of the land based sections with previously tuned data from odp site1262 from the southern atlantic is challenged our choice is consistent with original tuning at zumaia but shifts one 100 ky cycle older previous tuning from site 1262 along the interval above c27n under the preferred tuning scheme the d s boundary can be given an age of 61 641 0 040 ma on the la04 orbital solution

latest danian carbon isotope anomaly and associated environmental change in the southern tethys nile basin egypt abstract during the palaeocene and eocene epochs 65 5 33 9 ma the earth experienced the warmest conditions of the cenozoic this palaeogene greenhouse episode is characterized by several short lived negative carbon isotope 13 c excursions which are usually interpreted as transient warming events hyperthermals9 as indicated by rising temperatures of surface and bottom waters and accompanied carbonate dissolution in deep sea settings among these events the palaeocene eocene thermal maximum petm c 55 5 ma is globally the best documented and most prominent further negative 13 c anomalies have recently been identified in the eocene but the early to middle palaeocene has mostly been neglected here benthic foraminiferal 13 c records are presented from four upper danian lower selandian sections in the nile basin eastern egypt all records show a negative 13 c shift with an amplitude of up to 2 at the base of planktonic foraminiferal subzone p3b c 61 ma the supra regional nature of this event is emphasized by correlation with a well dated similar 13 c record from zumaia spain lithological changes the 13 c signature and biotic responses strongly resemble those of the petm in egypt which leads to the hypothesis that this latest danian event9 lde may represent another early palaeocene hyperthermal

palaeoenvironmental turnover across the ypresian lutetian transition at the agost section southastern spain in search of a marker event to define the stratotype for the base of the lutetian stage marker events to define the stratotype for the base of the lutetian stage are poorly defined to elucidate such markers and characterize palaeoenvironmental turnovers we conducted an integrated study of the ypresian lutetian y l early middle eocene transition at the continuous agost section southeastern spain this 115 m thick section which consists of hemipelagic marls intercalated with hemipelagic limestones and turbidity sandstones spans from planktic foraminiferal zones p9 to p12 e7 to e10 and calcareous nannofossil zones cp11 to cp14a np13 to np16 we report quantitative analyses of planktic and benthic foraminifera and characterization of trace fossil assemblages that are integrated with mineralogical analyses relative to benthic forms planktic foraminifera constitute more than 80 of the foraminiferal assemblage we found that the most abundant planktic species belong to the genera acarinina morozovella subbotina and psudohastigerina benthic foraminiferal assemblages are strongly dominated by calcareous taxa with bolivinids being the most abundant group trace fossils showed the succession nereites zoophycos cruziana ichnofacies throughout the agost section in addition to changes in palaeobathymetry we deduced that quantity and quality of organic matter flux influenced by turbidity currents are the main factors controlling benthic assemblages we distinguished several mineralogical boundaries at the agost section each associated with lithological facies changes suggesting a change in provenance rather than changes in weathering conditions we made three observations that indicate an increase in sea water temperatures or a possible hyperthermal event related to the first occurrence fo of hantkeninids i e the p9 p10 boundary 1 a distinct peak in abundance of the benthic foraminifera aragonia aragonensis 2 the low diversity of benthic foraminiferal assemblages and 3 the occurrence of the planktic foraminifera clavigerinella eocenica and clavigerinella jarvisi benthic foraminiferal and trace fossil assemblages also suggest an associated relative fall of sea level from upper middle bathyal to sublittoral depths these characteristic indicators point to this boundary as a promising feature for defining the global stratotype section and point gssp for the base of the lutetian stage however complementary magnetobiostratigraphic studies carried out at the agost section point to the fo of calcareous nannofossil blackites inflatus base of cp12b which occurred 3 5 myr before the p9 p10 boundary as the most suitable primary marker event whatever the marker event chosen all the successive events recognized at the agost section allow a complete characterization of the y l transition and thus this section may be a suitable candidate to locate the gssp for the ypresian lutetian boundary c 2008 elsevier b v all rights reserved

palaeoenvironmental changes during the danian selandian boundary interval the ichnological record at the sopelana section basque basin w pyrenees abstract ichnological analysis was conducted in the danian selandian d s boundary interval from the sopelana section basque basin northern spain to improve characterization of the recently defined global stratotype section and point of the base of the selandian stage middle paleocene in the nearby zumaia section and to interpret the danian selandian boundary event with its associated palaeoenvironmental changes the trace fossil assemblage of the boundary interval is relatively scarce and shows low diversity consisting of chondrites planolites thalassinoides trichichnus and zoophycos which cross cut a diffuse burrow mottled background typical of a normal burrowing tiered community distribution of trace fossils shows local drops in abundance and diversity just above the d s boundary and about half a metre upwards into the succeeding selandian generally the selandian part of the section has slightly lower trace fossil diversity and abundance this is interpreted as due to a higher detrital food supply corresponding to a sea level fall in contrast to a decreased food supply during the selandian sea level rise smaller scale fluctuations of trace fossil diversity and abundance are also interpreted as due more to food content fluctuations in the sediment than to oxygenation of pore waters results reveal the minor influence of an extreme warming event hyperthermal conditions at the d s boundary which affected the whole benthic habitat contrarily a probable major effect of sea level fluctuations can be envisaged which determined variations in siliciclastic input and food content

a model study of the angola benguela frontal zone sensitivity to atmospheric forcing 1 a regional ocean model is applied to the tropical south east atlantic ocean in order to investigate the sensitivity of the intensity and position of the angola benguela frontal zone the results suggest that the position of the angola benguela frontal zone is mainly determined by opposing northward and southward flow within 2 degrees off the coast the windstress curl plays a major role in altering the position of the angola benguela frontal zone as it controls the southeastward flow of the south equatorial counter current the opposing northward flow is mainly the result of geostrophic adjustment to coastal upwelling driven by the meridional windstress the strength of the frontal zone is found to be related to the strength of the southerly windstress that controls the coastal upwelling

foraminiferal and δ13c isotopic event stratigraphy across the danian selandian transition at zumaya northern spain chronostratigraphic implications unconformity characterized by a ma jor lithological shift from greyish white oxic limestone chalk of the danskekalk fm upper danian to suboxic glauconitic green sand of the lellinge greensand fm lower selan dian overlain by grey marl and clay of the kerteminde marl fm middle selandian this unconformity was correlated with the sequence bound ary between cycles ta 1 3 and ta 1 4 abstract the zumaya section northern spain is a suitable candidate to define the global stratotype section and point for the base of the selandian stage palaeocene because of its excellent accessibility exposure and stratigraphic continuity uncertain ties exist however with regard to the stratigraphic horizon where to place the danian selandian d s boundary five potential stratigraphic horizons hds1 to hds5 to define the d s boundary have been identified at zumaya based on integrated stratigraphic studies that include quantitative plank tic and benthic foraminiferal results as well as d 13 c isotopic and lithological data two of these horizons hds2 and hds4 placed in zone c26r appear to have particularly good potential for serving as the d s boundary marker because they may represent significant global palaeoceanographic palaeoclimatic and eustatic events

biostratigraphic and magnetostratigraphic intercalibration of latest cretaceous and paleocene depositional sequences from the deep water basque basin western pyrenees spain abstract latest cretaceous late maastrichtian and paleocene depositional sequences from the deep water basque basin have been calibrated with published 1 2 and newly acquired magnetostratigraphic data sequences mostly consist of hemipelagic marls and limestones and their relative ages are well constrained with planktic foraminifera they accumulated during a phase of tectonic tranquillity and reduced clastic input into the basin and therefore they can be attributed to eustatic sea level changes with reasonable confidence on the basis of the planktic foraminifera zonation a good match has been observed previously between the depositional sequences of the basque basin and specific sea level cycles of the 1988 version of the exxon global cycle chart gcc 3 here a new attempt at correlation using their respective magnetostratigraphic data has failed to confirm such a match the disagreements observed may indicate that for the studied interval 1 the current planktic foraminifera biostratigraphy lacks the necessary level of resolution to ensure synchrony between sequences of different basins and or 2 the magnetostratigraphy of the gcc needs to be revised whatever the case the new findings lend support for some criticism on the use of the gcc for interregional correlations