PALEOCENE-EOCENE THERMAL MAXIMUM AND EOCENE CLIMATE EVENTS

Environmental changes during the Cretaceous-Paleogene mass extinction and Paleocene-Eocene Thermal Maximum: Implications for the Anthropocene

TitleEnvironmental changes during the Cretaceous-Paleogene mass extinction and Paleocene-Eocene Thermal Maximum: Implications for the Anthropocene
Publication TypeJournal Article
Year of Publication2018
AuthorsKeller, G, Mateo, P, Punekar, J, Khozyem, H, Gertsch, B, Spangenberg, J, Bitchong, AMbabi, Adatte, T
JournalGondwana Research
Volume56
Pagination69–89
Date Publishedapr
Abstract

The Cretaceous-Paleogene boundary (KPB) mass extinction (~66.02 Ma) and the Paleocene-Eocene Thermal Maximum( PETM)(~55.8Ma) are two remarkable climatic and faunal events in Earth's history that have implications for the current Anthropocene global warming and rapid diversity loss. Here we evaluate these two events at the stratotype localities in Tunisia and Egypt based on climatewarming and environmental responses recorded in faunal and geochemical proxies. The KPBmass extinction is commonly attributed to the Chicxulub impact, but Deccan volcanism appears as amajor culprit.Newmercury analysis reveals thatmajor Deccan eruptions accelerated during the last 10 ky and reached the tipping point leading up to themass extinction. During the PETM, climatewarmed rapidly by ~5 °C,which is mainly attributed tomethane degassing from seafloor sediments during global warming linked to the North Atlantic Igneous Province (NAIP). Biological effectswere transient,marked by temporary absence ofmost planktic foraminifera due to ocean acidification followed by the return of the pre-PETM fauna and diversification. In contrast, the current rapid rise in atmospheric CO2 and climate warming are magnitudes faster than at the KPB or PETM events leading to predictions of a PETM-like response as best case scenario and rapidly approaching sixth mass extinction as worst-case scenario.  PDF

URLhttps://doi.org/10.1016/j.gr.2017.12.002
DOI10.1016/j.gr.2017.12.002

Deccan volcanism induced high-stress environment during the Cretaceous–Paleogene transition at Zumaia, Spain: Evidence from magnetic, mineralogical and biostratigraphic records

TitleDeccan volcanism induced high-stress environment during the Cretaceous–Paleogene transition at Zumaia, Spain: Evidence from magnetic, mineralogical and biostratigraphic records
Publication TypeJournal Article
Year of Publication2018
AuthorsFont, E, Adatte, T, Andrade, M, Keller, G, Bitchong, AMbabi, Carvallo, C, Ferreira, J, Diogo, Z, Mirão, J
JournalEarth and Planetary Science Letters
Volume484
Pagination53–66
Date Publishedfeb
Abstract

We conducted detailed rock magnetic, mineralogical and geochemical (mercury) analyses spanning the Cretaceous–Paleogene boundary (KPB) at Zumaia, Spain, to unravel the signature of Deccan-induced climate and environmental changes in the marine sedimentary record. Our biostratigraphic results show that Zumaia is not complete, and lacks the typical boundary clay, zone P0 and the base of zone P1a(1) in the basal Danian. Presence of an unusual ∼1m-thick interval spanning the KPB is characterized by very low detrital magnetite and magnetosome (biogenic magnetite) contents and by the occurrence of akaganéite, a very rare mineral on Earth in oxidizing, acidic and hyper-chlorinated environments compatible with volcanic settings. These benchmarks correlate with higher abundance of the opportunist Guembelitria cretacea species. Detrital magnetite depletion is not linked to significant lithological changes, suggesting that iron oxide dissolution by acidification is the most probable explanation. The concomitant decrease in magnetosomes, produced by magnetotactic bacteria at the anoxic–oxic boundary, is interpreted as the result of changes in seawater chemistry induced by surficial ocean acidification. Mercury peaks up to 20–50 ppb are common during the last 100 kyr of the Maastrichtian (zone CF1) but only one significant anomaly is present in the early Danian, which is likely due to the missing interval. Absence of correlation between mercury content (R2 = 0.009) and total organic carbon (R2 = 0.006) suggest that the former originated from the Deccan Traps eruptions. No clear relation between the stratigraphic position of the mercury peaks and the magnetite-depleted interval is observed, although the frequency of the mercury peaks tends to increase close to the KPg boundary. In contrast to Bidart (France) and Gubbio (Italy), where magnetite depletion and akaganéite feature within a ∼50cm-thick interval located 5 cm below the KPg boundary, the same benchmarks are observed in a 1m-thick interval encompassing the KPg boundary at Zumaia. Results reinforce the synchronism of the major eruptions of the Deccan Traps Magmatic Province with the Cretaceous–Paleogene (KPg) mass extinction and provide new clues to better correlate the Deccan imprint of the global sedimentary record.  PDF

URLhttps://doi.org/10.1016/j.epsl.2017.11.055
DOI10.1016/j.epsl.2017.11.055

Environmental changes during the Cetaceous-Paleogene mass extinction and Paleocene-Eocene thermal maximum: Implications for the Anthropocene

TitleEnvironmental changes during the Cetaceous-Paleogene mass extinction and Paleocene-Eocene thermal maximum: Implications for the Anthropocene
Publication TypeJournal Article
Year of Publication2017
AuthorsKeller, G, Mateo, P, Punekar, J, Khozyem, H, Gertsch, B, Spangenberg, J, Bitchong, A, Adatte, T
JournalGondwana Research
Date Publisheddec
Abstract

The Cretaceous-Paleogene boundary (KPB) mass extinction (~ 66.02 Ma) and the Paleocene-Eocene Thermal Maximum (PETM) (~ 55.8 Ma) are two remarkable climatic and faunal events in Earth's history that have implications for the current Anthropocene global warming and rapid diversity loss. Here we evaluate these two events at the stratotype localities in Tunisia and Egypt based on climate warming and environmental responses recorded in faunal and geochemical proxies. The KPB mass extinction is commonly attributed to the Chicxulub impact, but Deccan volcanism appears as a major culprit. New mercury analysis reveals that major Deccan eruptions accelerated during the last 10 ky and reached the tipping point leading up to the mass extinction. During the PETM, climate warmed rapidly by ~ 5 °C, which is mainly attributed to methane degassing from seafloor sediments during global warming linked to the North Atlantic Igneous Province (NAIP). Biological effects were transient, marked by temporary absence of most planktic foraminifera due to ocean acidification followed by the return of the pre-PETM fauna and diversification. In contrast, the current rapid rise in atmospheric CO2 and climate warming are magnitudes faster than at the KPB or PETM events leading to predictions of a PETM-like response as best case scenario and rapidly approaching sixth mass extinction as worst-case scenario.

URLhttps://doi.org/10.1016/j.gr.2017.12.002
DOI10.1016/j.gr.2017.12.002

Maastrichtian to Eocene subsurface stratigraphy of the Cauvery basin and correlation with Madagascar

TitleMaastrichtian to Eocene subsurface stratigraphy of the Cauvery basin and correlation with Madagascar
Publication TypeJournal Article
Year of Publication2016
AuthorsKeller, G, Jaiprakash, BC, Reddy, AN
JournalJournal of the Geological Society of India
Volume87
Pagination5–34
Date Published01/2016
Abstract

Late Maastrichtian through middle Eocene planktic foraminiferal biostratigraphy and erosion patterns from three Cauvery basin wells are compared with the Krishna-Godavari basin, Madagascar and South Atlantic Site 525A. Maastrichtian sedimentation appears continuous at DSDP site 525A and substantially complete in the Cauvery basin and Madagascar for the interval from ~70.3 to 66.8 Ma (zones CF6-CF3). But the latest Maastrichtian through early Paleocene record is fragmented, except for some Krishna-Godavari and Cauvery basin wells protected from erosion by Deccan traps or graben deposition, respectively. Hiatuses are observed correlative with sea level falls at 66.8, 66.25, 66.10, 65.7, 63.8 and 61.2 Ma with erosion amplified by local tectonic activity including doming and uplift due to Deccan volcanism.

Throughout this region the Cretaceous-Paleogene transition (magnetochron C29r-C29n, 66.25-65.50 Ma) is preserved only in deep wells of the Krishna-Godavari basin where Deccan Traps protected intertrappean sediments from erosion. The late Paleocene to middle Eocene marine record was recovered from two Cauvery basin wells with hiatuses correlative with low sea levels at ~49.0-56.5 Ma (zones P4c-E6) and ~53.0-55.3 Ma (zones E1-E4) at the ridge well KALI-H. A nearly complete record was recovered from well AGA, including the PETM event (zones E1-E2), which marks this an excellent reference section for India.

Similarity in erosion and sedimentation patterns of the late Maastrichtian to middle Paleocene from India to Madagascar and South Atlantic is mainly attributed to climate changes and sea level falls, regional tectonic activity from the Bay of Bengal to Madagascar, and uplift and doming in the Cauvery and K-G basins as a result of Deccan volcanism. Directly correlative with Deccan volcanism are high stress environments for marine calcifiers, as observed by species dwarfing, reduced diversity and blooms of the disaster opportunist Guembelitria cretacea in magnetochron C30n (zones CF4-CF3) correlative with Deccan phase-1 and Ninetyeast Ridge volcanism, in C29r (zones CF2-CF1) correlative with Deccan phase-2 and in C29n (zone P1b) correlative with Deccan phase-3 marking volcanism as the most important stress factor in the end-Cretaceous mass extinction and delayed evolution of planktic foraminifera.  PDF

 

 

URLhttps://link.springer.com/article/10.1007/s12594-016-0370-4
DOI10.1007/s12594-016-0370-4

New geochemical constraints on the Paleocene–Eocene thermal maximum: Dababiya (GSSP), Egypt

TitleNew geochemical constraints on the Paleocene–Eocene thermal maximum: Dababiya (GSSP), Egypt
Publication TypeJournal Article
Year of Publication2015
AuthorsKhozyem, H, Adatte, T, Spangenberg, JE, Keller, G, Tantawy, AAziz, Ulianov, A
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume429
Pagination117–135
Date Published07/2018
Abstract

The Paleocene-Eocene Thermal Maximum (PETM) shows an extraordinary drop in the δ13C of carbonate and organic matter across the globe, suggesting massive release of 13C-depleted carbon dioxide into the ocean and atmosphere over a very short time interval (probably < 20ky). We report a geochemical and mineralogical study of 106 samples spanning the most expanded PETM at the Dababiya Global Stratotype Standard section and Point (GSSP) near Luxor, Egypt. The field and laboratory observations reveal that the deposition occurred in a submarine channel extended laterally about 200 m with the deepest part (~ 0.88 m) at the designated GSSP, although all bio-zones are present. Stable isotope records of both carbonate and organic carbon show decreases starting 0.6 m below the Paleocene-Eocene boundary (PEB) and culminating at the erosion surface. A persistent shift in δ15Norg values to near zero reflects a gradual increase in bacterial activity. High Ti, K and Zr and low Si contents at the PEB coincide with increased kaolinite contents, which suggests intense chemical weathering under more humid conditions at the PETM onset. Two negative Ce-anomalies indicate intervals of anoxic conditions during the lower and middle PETM (base and top of zone E1). The first anoxic event is represented by a negative Ce-anomaly, high V/C rand V/V + Ni ratios, negative Mn* and an abundance of idiomorphic pyrite crystals that indicate anoxic to euxinic conditions. The anoxic event (middle PETM) is marked by high U, Mo, V, Fe and abundant small sized (2–5 μm) pyrite framboids, increased Cu, Ni, and Cd at the same level suggesting anoxic conditions linked to high surface water productivity. Above this interval, oxic conditions returned as indicated by the precipitation of phosphorus and barium. These data reveal an expanded PETM interval marked by intense weathering as a crucial parameter during the recovery phase.  PDF

URLhttps://doi.org/10.1016/j.palaeo.2015.04.003
DOI10.1016/j.palaeo.2015.04.003

The Paleocene-Eocene GSSP at Dababiya, Egypt – Revisited

TitleThe Paleocene-Eocene GSSP at Dababiya, Egypt – Revisited
Publication TypeJournal Article
Year of Publication2014
AuthorsKhozyem, H, Adatte, T, Keller, G, Tantawy, AAAM, Spangenberg, JE
JournalEpisodes
Volume37
Issue2
Start Page78
Date Published06/2014
Abstract

We investigated the Paleocene-Eocene boundaryGSSP (Dababiya quarry) near Luxor, Egypt, in twonearby (25m and 50m) sequences based on high-resolution biostratigraphy, lithostratigrapy, mineralogyand geochemistry. Results confirm the many positiveaspects of the Dababiya GSSP but also show potentiallyserious limiting factors: (1) the GSSP is located in thedeepest part of a ~200 m wide submarine channel, whichlimits its use as global type section. (2) Some lithologicunits identified at the GSSP are absent or thin out anddisappear within the channel and beyond. (3) The P-Eboundary is placed at the base of a clay layer above anerosion surface with variable erosion of latest Paleoceneand earliest Eocene sediments. (4) The current definitionof the P-E boundary as marked by the abrupt onset ofthe carbon isotope excursion at the base of a clay layeris not supported at the GSSP because 50m to the leftthe excursion begins gradually 60cm below the P-Eboundary and reaches minimum values in the boundaryclay. With awareness of these limiting factors andrecognition of the gradual onset of the PETM excursionthe GSSP can contribute significantly to a more completeunderstanding of this global warm event.  PDF

URLhttp://www.researchgate.net/publication/264417759_The_Paleocene-Eocene_GSSP_at_Dababiya_Egypt__Revisited

Palaeoenvironmental and climatic changes during the Palaeocene–Eocene Thermal Maximum (PETM) at the Wadi Nukhul Section, Sinai, Egypt

TitlePalaeoenvironmental and climatic changes during the Palaeocene–Eocene Thermal Maximum (PETM) at the Wadi Nukhul Section, Sinai, Egypt
Publication TypeJournal Article
Year of Publication2013
AuthorsKhozyem, H, Adatte, T, Spangenberg, J, Tantawy, AAAM, Keller, G
JournalJournal of the Geological Society
Volume170
Pagination341-352
Abstract

The Palaeocene–Eocene Thermal Maximum (PETM) interval at the Wadi Nukhul section (Sinai, Egypt) is represented by a 10 cm thick condensed clay-rich layer corresponding to the NP9a–NP9b nannofossil subzone boundary. The Wadi Nukhul Palaeocene–Eocene boundary (PEB) is characterized by (1) an abrupt negative excursion in carbonate and organic carbon isotope ratios (−6‰ in δ13Ccarb and −2‰ δ13Corg), (2) an abrupt persistent negative shift in organic nitrogen isotope values (δ15Norg), (3) a significant increase in phosphorus concentrations just above the carbon isotope excursion, (4) a decrease in carbonate content and significant increase in kaolinite and (5) high vanadium and low manganese contents coincident with the occurrence of framboidal pyrite. The abrupt correlative isotopic excursions of δ13Ccarb, δ13Corg and δ15N suggest that the lowermost part of the PETM is missing. The decrease in carbonate content indicates dilution by high detrital input triggered by acid weathering and carbonate dissolution in response to increased atmospheric CO2 resulting from the oxidation of methane. The sudden increase in kaolinite content reflects a short-lived change to humid conditions. The δ15N values close to 0‰ above the PEB suggest a bloom of N2-fixing cyanobacteria. Increased bacterial activity may be either the cause or the result of the anoxia locally associated with the PETM.

URLhttp://jgs.lyellcollection.org/content/170/2/341.abstract
DOI10.1144/jgs2012-046

Micropaleontology in Multi-disciplinary research: Applications to OAE2 and KTB

TitleMicropaleontology in Multi-disciplinary research: Applications to OAE2 and KTB
Publication TypeBook Chapter
Year of Publication2013
AuthorsKeller, G
Book TitleProceedings of XXIII Indian Colloquium on Micropaloentology and Stratigraphy and International Symposium on Global Bioevents in Earth's History
Volume1
ChapterPart I, Pp. 1
EditionSpecial Publication
PublisherGeological Society of India
CityBangalore
ISBN978-93-80998-08-04
Keywordsapplications
URLhttp://www.geosocindia.com/index.php?page=shop.product_details&flypage=flypage-ask.tpl&product_id=227&category_id=20&option=com_virtuemart&Itemid=6

Paleoclimate and Paleoenvironment of the Naredi Formation (Early Eocene), Kutch, Gujarat, India

TitlePaleoclimate and Paleoenvironment of the Naredi Formation (Early Eocene), Kutch, Gujarat, India
Publication TypeBook Chapter
Year of Publication2013
AuthorsKhozyem, H, Adatte, T, Keller, G, Spangenberg, J, Saravanan, N, Bajpai, S
Book TitleProceedings of XXIII Indian Colloquium on Micropaloentology and Stratigraphy and International Symposium on Global Bioevents in Earth's History
Volume1
ChapterPart III, Pp. 165
EditionSpecial Publication
PublisherGeological Society of India
CityBangalore
ISBN978-93-80998-08-4
KeywordsGlobal events, KTB, PE
Abstract

The Naredi Formation of Kutch, Gujarat, India, is early Eocene in age and marks the first marine transgression above the last Deccan traps. Sediment deposition occurred in a shallow inner shelf environment that varied from a brackish lagoon to brackish, normal inner shelf and to marginal marine environments. The section can be divided into 2 main transgressive cycles interrupted by a regression phase that is marked by a well-defined sequence boundary marked by a root-bearing paleosoil. Three intervals yielded common to abundant benthic foraminiferal assemblages. Planktic foraminifera are few to rare and restricted to the top of the section, except for Chiloguembelina trinitatensis. An early Eocene age can be attributed to the Naredi section based primarily on larger benthic foraminifera (SBZ8 to SBZ11, equivalent to planktic foraminiferal biozones E4 to E6), rare planktic foraminifera, the stable isotope curve and its correlation with marine sections and sequence stratigraphy. Sediments of the transgression/regression cycles were derived from physical and chemical-weathering processes of basaltic rocks as indicated by the different geochemical proxies. Carbon isotope analyses of bivalve shells and organic matter reveal a negative excursion that is correlative with the global Early Eocene excursion. The presence of fish bones, fish teeth and organic matter can be related to the Early Eocene climatic optimum. Clay mineral data from the Naredi Formation indicate variably hot humid to arid climate conditions. 

URLhttp://www.geosocindia.com/index.php?page=shop.product_details&flypage=flypage-ask.tpl&product_id=227&category_id=20&option=com_virtuemart&Itemid=6

Biostratigraphy and foraminiferal paleoecology of the Early Eocene Naredi Formation, SW Kutch, India

TitleBiostratigraphy and foraminiferal paleoecology of the Early Eocene Naredi Formation, SW Kutch, India
Publication TypeBook Chapter
Year of Publication2013
AuthorsKeller, G, Khozyem, H, Adatte, T, Spangenberg, J
Book TitleProceedings of XXIII Indian Colloquium on Micropaloentology and Stratigraphy and International Symposium on Global Bioevents in Earth's History
Volume1
ChapterPart III, Pp. 183
EditionSpecial Publication
PublisherGeological Society of India
CityBangalore
ISBN978-93-80998-08-4
KeywordsGlobal Bioevents, KTB, PE
Abstract

The Naredi Formation in southwestern Kutch overlies the last Deccan Trap deposited during the early Paleocene. The lower part of the Naredi Formation (2.8-4.2 m from base) is of early Eocene (Ypresian) age (SBZ8, E4) based on larger foraminifera and rare planktic foraminifera, whereas the upper part (9.3-11 m, including the Assilina limestone) is of late early Eocene age (SBZ11, E6). There is no age control for the basal 0-2.8 m and between 4.2-9.3 m because microfossils are rare or absent. Small benthic and rare planktic foraminifera are common in three short intervals and indicate deposition in a brackish to normal marine inner shelf environment (SBZ8, E4), brackish environment (middle of section, no age control) and inner shelf to marginal marine environment (SBZ11, E6). Two phases of marine transgressions can be identified with the maximum transgressions in each phase coincident with the lower and upper foraminiferal assemblages. A paleosol indicated by root traces and burrows (5.9 m) represents a regression and possibly sequence boundary.  PDF

URLhttp://www.geosocindia.com/index.php?page=shop.product_details&flypage=flypage-ask.tpl&product_id=227&category_id=20&option=com_virtuemart&Itemid=6

The Paleocene-Eocene transition in the marginal northeastern Tethys (Kazakhstan and Uzbekistan)

TitleThe Paleocene-Eocene transition in the marginal northeastern Tethys (Kazakhstan and Uzbekistan)
Publication TypeJournal Article
Year of Publication2000
AuthorsBolle, M-P, Pardo, A, Hinrichs, K-U, Adatte, T, Von Salis, K, Burns, S, Keller, G, Muzylev, N
JournalInternational Journal of Earth Sciences
Volume89
Issue2
Pagination390 - 414
Date PublishedOct-09-2001
ISSN1437-3254
Abstract

We studied two sections that accumulated during the Paleocene–Eocene transition in shelf waters in the northeastern Tethys. Stable carbon isotopic compositions of marine and terrestrial biomarkers are consistent with a 13C depletion in the oceanic and atmospheric carbon dioxide pools during the Late Paleocene Thermal Maximum (LPTM; Subzone P5b). The 2–3‰ negative δ 13C excursion in planktic foraminifera coincides with minimum δ 18O values, an incursion of transient subtropical planktic foraminiferal fauna, and the occurrence of an organic-rich sapropelite unit in Uzbekistan, which accumulated at the onset of a transgressive event. Biomarker distributions and hydrogen indices indicate that marine algae and bacteria were the major organic matter sources. During the Late Paleocene (Subzones P4 and P5a), the marginal northeastern Tethys experienced a temperate to warm climate with wet and arid seasons. Most likely, warm and humid climate initiated during the LPTM (Subzone P5b) and subsequently extended during the Eocene (Zone P6) onto adjacent land areas of the marginal northeastern Tethys.   PDF

URLhttp://link.springer.com/article/10.1007%2Fs005310000092
DOI10.1007/s005310000092
Short TitleInternational Journal of Earth Sciences

Paleoecologic and paleoceanographic evolution of the Tethyan realm during the Paleocene-Eocene transition

TitlePaleoecologic and paleoceanographic evolution of the Tethyan realm during the Paleocene-Eocene transition
Publication TypeJournal Article
Year of Publication1999
AuthorsPardo, A, Keller, G, Oberhaensli, H
JournalThe Journal of Foraminiferal Research
Volume29
Pagination37-57
Abstract

Analyses of planktic foraminifera and stable isotopes from sections in Kazakstan (Kaurtakapy), Spain (Alamedilla, Zumaya) and the Bay of Biscay (DSDP Site 401) suggest similar overall paleoecologic, paleoceanographic and paleoclimatic patterns during the Paleocene-Eocene (P-E) transition, although regional differences are apparent. The major difference in delta 13 C values measured in benthic Cibicidoides spp. is seen in the gradual decrease of approximately 1 per mil in Subzones P5a and P5b in the Tethys and its absence elsewhere. In planktic foraminifera, regional differences are marked by changes in the relative abundances of warm water taxa and cool water subbotinids. Overall, the P-E transition is marked by the following sequence of faunal and isotopic events. Near the P-E boundary (Zone P5b) and coincident with the benthic foraminiferal extinction event and the delta 13 C excursion, warm water planktic foraminiferal assemblages (e.g., acarininids, igorinids and morozovellids) rapidly diversified, suggesting surface water warming. Thereafter (Zone P5b/P6a), increased abundance in cool-temperate planktic foraminifera (e.g., subbotinids) and a concomitant increase in the abundance of low oxygen tolerant chiloguembelinids, suggest cooling and hypoxic conditions at thermocline depths that may have been due to changes in watermass stratification and upwelling. This cooling is followed by a second more gradual warming, where acarininids slowly replace morozovellids as the dominant surface dwellers. The biozonation of Berggren and others (1995) has been modified by subdividing Zone P5 into Subzones P5a and P5b based on the first appearance of Acarinina sibaiyaensis and/or Acarinina africana. This modification of Zone P5 provides greater age control for the P-E event with the P5a/P5b boundary coincident with the BFEE and the delta 13 C excursion.

URLhttp://jfr.geoscienceworld.org/content/29/1/37.abstract

The Paleocene-Eocene transition in the southern Tethys (Tunisia); climatic and environmental fluctuations

TitleThe Paleocene-Eocene transition in the southern Tethys (Tunisia); climatic and environmental fluctuations
Publication TypeJournal Article
Year of Publication1999
AuthorsBolle, MP, Adatte, T, Keller, G, von Salis, K, Burns, S
JournalBulletin de la Societe Geologique de France
Volume170
Pagination661-680
Abstract

This study, based on a multidisciplinary approach including micropaleontology, sedimentology, mineralogy and geochemistry, evaluates the Paleocene-Eocene transition in Tunisia. At Foum Selja, sediment deposition occurred in the shallow, restricted Gafsa Basin influenced by the adjacent Saharan Platform. During the early Paleocene this area experienced a warm and humid climate that changed to warm but arid climatic conditions during the Paleocene-Eocene transition. At Elles the sediment deposition in the El Kef Basin occurred in an open marine environment connected to the Tethys. During the late Paleocene, the Tethyan region was submitted to a seasonal warm climate changing to a warm and humid climate across the P/E transition and becoming seasonal/arid in the early Eocene. From Africa to northern Europe, kaolinite, a strong marker of warmth and humidity disappeared diachronously suggesting a latitudinal shift in the source area of this mineral and consequently in the climatic zones, from lower to higher latitudes. The P/E transition observed at Elles corresponds to a 2.7 m thick clay layer and is marked by a drastic decrease in carbonate sedimentation, a negative delta 13 C excursion of 1.3 per mil and increased detrital input. The presence of a condensed interval, the accumulation of phosphate deposits after the P/E event, which obliterate the original isotopic signal and strong dissolution of the planktic fauna and flora in these phosphatic layers, all are criteria that prevent the Elles section to be a potential GSSP candidate for the P/E boundary.

URLhttp://bsgf.geoscienceworld.org/content/170/5/661.abstract

The Paleocene-Eocene transition in the southern Tethys (Tunisia); climatic and environmental fluctuations

TitleThe Paleocene-Eocene transition in the southern Tethys (Tunisia); climatic and environmental fluctuations
Publication TypeJournal Article
Year of Publication1999
AuthorsBolle, MP, Adatte, T, Keller, G, von Salis, K, Burns, S
JournalBulletin de la Société Géologique de France
Volume170
Pagination661
Abstract

This study, based on a multidisciplinary approach including micropaleontology, sedimentology, mineralogy and geochemistry, evaluates the Paleocene-Eocene transition in Tunisia. At Foum Selja, sediment deposition occurred in the shallow, restricted Gafsa Basin influenced by the adjacent Saharan Platform. During the early Paleocene this area experienced a warm and humid climate that changed to warm but arid climatic conditions during the Paleocene-Eocene transition. At Elles the sediment deposition in the El Kef Basin occurred in an open marine environment connected to the Tethys. During the late Paleocene, the Tethyan region was submitted to a seasonal warm climate changing to a warm and humid climate across the P/E transition and becoming seasonal/arid in the early Eocene. From Africa to northern Europe, kaolinite, a strong marker of warmth and humidity disappeared diachronously suggesting a latitudinal shift in the source area of this mineral and consequently in the climatic zones, from lower to higher latitudes. The P/E transition observed at Elles corresponds to a 2.7 m thick clay layer and is marked by a drastic decrease in carbonate sedimentation, a negative delta 13 C excursion of 1.3 per mil and increased detrital input. The presence of a condensed interval, the accumulation of phosphate deposits after the P/E event, which obliterate the original isotopic signal and strong dissolution of the planktic fauna and flora in these phosphatic layers, all are criteria that prevent the Elles section to be a potential GSSP candidate for the P/E boundary.   PDF

URL+ http://dx.doi.org/

Biostratigraphy, mineralogy and geochemistry of the Trabakua Pass and Ermua sections in Spain : Paleocene-Eocene transitions

TitleBiostratigraphy, mineralogy and geochemistry of the Trabakua Pass and Ermua sections in Spain : Paleocene-Eocene transitions
Publication TypeMiscellaneous
Year of Publication1998
AuthorsKeller, G, Bolle, M-P, Adatte, T
Abstract

Isotopie, geochemical and bulk mineralogical analyses in the Trabakua and Ermua sections. Basque Basin, reveal major changes across the Paleocene- Eocene transition. Expanded sedimentary records exhibit a gradual decrease of 1.0 %o in 5 "C values in the lower part of Zone P5 followed by a more rapid 3 %o negative excursion. The 3 %si S l3C excursion is associated with an abrupt decrease in carbonate sedimentation, increased detrital flux and decreased grain size which suggest changes in marine/atmospheric currents and/or size and structure of the ocean carbon reservoir. The clays recognized at Trabakua record a deep burial diagenesis as indicated by two generations of chlorite. the presence of mixed-layers chlorite-smectite and illite-smectite. the absence of smectite and the near absence of kaolinite. The very low 5 "O values (<-3.5%o) throughout the Trabakua and Ermua sections reflect diagenetic al¬ teration rather than paleotemperatures. Because of deep burial diagenesis and very poorly preserved microfossils. the Trabakua Pass and Ermua sections are not optimal potential stratotypes for the Paleocene-Eocene boundary.  PDF

DOI10.5169/seals-168405

Stability and change in Tethyan planktic foraminifera across the Paleocene–Eocene transition

TitleStability and change in Tethyan planktic foraminifera across the Paleocene–Eocene transition
Publication TypeJournal Article
Year of Publication1998
AuthorsLu, G, Keller, G, Pardo, A
JournalMarine Micropaleontology
Volume35
Pagination203–233
Date Publisheddec
Abstract

Examination of planktic foraminifera in the Tethys basin during the Paleocene–Eocene transition reveals two stasis intervals that are separated by a major saltation event coincident with the P–E short-term perturbation in global climate and oceanography. Changes occurred at many spatial and temporal scales as well as many taxonomic and ecologic hierarchical levels, though with various rates and magnitudes. The stasis intervals are marked by slow changes at the species level and account for 50% of the observed first and last appearances during a 2.5 Myr interval. The saltation event is marked by rapid changes at the species and morpho-guild levels and accounts for the remaining 50% of first and last appearances during an interval of about 100–200 kyr. Despite these changes, many taxonomic and ecologic units, such as the depth assemblages and genera, and faunal parameters, such as species richness and turnover rates, are stable with respect to the P–E perturbation. This coexistence of change and stability marks the crisis of Tethyan planktic foraminifera across the P–E transition and reveals the possible dynamics of ecological evolution.   PDF

URLhttps://doi.org/10.1016/s0377-8398(98)00018-8
DOI10.1016/s0377-8398(98)00018-8

Abrupt climatic, oceanographic and ecologic changes near the Paleocene-Eocene transition in the deep Tethys basin: The Alademilla section, southern Spain

TitleAbrupt climatic, oceanographic and ecologic changes near the Paleocene-Eocene transition in the deep Tethys basin: The Alademilla section, southern Spain
Publication TypeJournal Article
Year of Publication1998
AuthorsLu, GY, Adatte, T, Keller, G, Ortiz, N
JournalEclogae Geologicae Helveticae
Volume91
Pagination293–306
Other NumbersFile 2
KeywordsARIDITY, CLAY-MINERALS, FAUNAL TURNOVER, PALEO-CLIMATE, PALEO-OCEANOGRAPHY, PALEOCENE-EOCENE TRANSITION, STABLE ISOTOPES, TETHYS, WARMING
Abstract

The Tethys is a critical region for investigating the mechanism(s) ofthe Paleocene-Eocene global change, because of its potential in producing warm saline water masses, a possible driving force for the deep ocean warming at this time. To examine climatic, oceanographic and ecologic changes in the deep Tethys basin, we conducted high resolution faunal, isotopic and mineralogic analyses across the P-E transition at the Alamedilla section (paleodepth between 1000 m and 2000 m) in southern Spain. At this location, foraminiferal delta(18)O values show little temperature change in surface waters, but a 4 degrees C warming in bottom waters. Comparison with deep-sea sites indicates that Antarctic intermediate water was consistently colder than Tethys bottom water. During the course of the P-E global change, however, the temperature difference between these two water masses was reduced from a previous 5 degrees C to 3 degrees C. Clay mineralogic analyses at the Alamedilla section indicate increased aridity in the Tethys region that contrastswith a humid episode on Antarctica during high-latitude warming. Foraminiferal delta(13)C values at Alamedilla show a negative excursion of1.7 parts per thousand in both surface and bottom waters with little change in the vertical delta(13)C gradient. Accumulation of organic and inorganic carbon in sediments decreased significantly, suggesting changes in the size and structure of the oceanic carbon reservoir. Associated with these climatic and oceanographic changes is a reorganization of the Tethys ecosystem, a benthic foraminiferal mass extinction, and planktonic foraminiferal assemblages marked by increased species turnover rates and high relative abundance of short-lived, opportunistic species that suggest increased instability.

URLhttp://serials.unibo.it/cgi-ser/start/it/spogli/df-s.tcl?prog_art=5977368&language=ITALIANO&view=articoli

Planktic foraminiferal turnover across the Paleocene-Eocene transition at (DSDP) Site 401, Bay of Biscay, North Atlantic

TitlePlanktic foraminiferal turnover across the Paleocene-Eocene transition at (DSDP) Site 401, Bay of Biscay, North Atlantic
Publication TypeJournal Article
Year of Publication1997
AuthorsPardo, A, Keller, G, Molina, E, Canudo, JI
JournalMarine Micropaleontology
Volume29
Pagination129–158
Date Publishedjan
Abstract

Planktic foraminifera across the Paleocene-Eocene transition at DSDP Site 401 indicate that the benthic foraminiferal mass extinction occurred within Subzone P 6a of Berggren and Miller (1988), or P5 of Berggren et al. (1995) and coincident with a sudden 2.0%. excursion in δ13C values. The benthic foraminiferal extinction event (BFEE) and δ13Cexcursion was accompanied by a planktic foraminiferal turnover marked by an influx of warm water species (Morozovella and Acarinina), a decrease in cooler water species (Subbotina), a sudden short-term increase in low oxygen tolerant taxa (Chiloguembelina), and no significant species extinctions. These faunal changes suggest climatic warming, expansion of the oxygen minimum zone, and a well stratified ocean water column. Oxygen isotope data of the surface dweller M. subbotina suggest climate warming beginning with a gradual 0.5%. decrease in δ18O in the 175 cm preceding the benthic foraminiferal extinction event followed by a sudden decrease of 1%. (4 °C) at the BFEE. The δ13C excursion occurred over 27 cm of sediment and, assuming constant sediment accumulation rates, represents a maximum of 23 ka. Recovery to pre-excursion gd13C values occurs within 172 cm, or about 144 ka. Climate cooling begins in Subzone P 6c as indicated by an increase in cooler water subbotinids and acarininids with rounded chambers and a decrease in warm water morozovellids.  PDF

URLhttps://doi.org/10.1016/s0377-8398(96)00035-7
DOI10.1016/s0377-8398(96)00035-7

Separating ecological assemblages using stable isotope signals; late Paleocene to early Eocene planktic foraminifera, DSDP Site 577

TitleSeparating ecological assemblages using stable isotope signals; late Paleocene to early Eocene planktic foraminifera, DSDP Site 577
Publication TypeJournal Article
Year of Publication1996
AuthorsLu, G, Keller, G
JournalThe Journal of Foraminiferal Research
Volume26
Issue2
Start Page103
Pagination103 - 112
Date Published04/1996
ISSN0096-1191
Abstract

Analysis of late Paleocene to early Eocene planktic foraminifera from DSDP Site 577 indicates the presence of two and possibly three isotopically and morphologically distinct assemblages. The surface dwelling assemblage includes species with pustulate-muricate wall texture (e.&, species of the genera MorozoveUa, Acarinina, lgorim, and Murikoglobigerina). This assemblage is characterized by light W80 values and large interspecific S’3C variation. It accounts for 82% of the population. The subsurface dwelling assemblage includes species with cancellate-pitted and smoothed-granulate wall textures (e+, species of the genera Subbotina, LLTurborotalia,” Planorotalites, Pseudohastigerina, and Chiloguembelina). This assemblage is characterized by heavier 6‘80 values and small interspecific SI3C variation. It accounts for 14% of the population. The questionable deep dwelling assemblage includes some species with pitted wall texture (e.g., species of the genus “Planorotalites”). This assemblage is characterized by the heaviest SI8O values and accounts for only 4% of the population.

URLhttp://jfr.geoscienceworld.org/content/26/2/103
DOI10.2113/gsjfr.26.2.103
Short TitleThe Journal of Foraminiferal Research

Long-term (105) or short-term (103) c13C excursion near the Palaeocene-Eocene transition: evidence from the Tethys

TitleLong-term (105) or short-term (103) c13C excursion near the Palaeocene-Eocene transition: evidence from the Tethys
Publication TypeJournal Article
Year of Publication1996
AuthorsLu, G, Keller, G, Adatte, T, Ortiz, N, Molina, E
JournalTerra Nova
Volume8
Issue4
Start Page347
Pagination347 - 355
Date PublishedJan-07-1996
ISSN0954-4879
Abstract

Expanded sedimentary records from the Tethys reveal unique faunal and isotopic changes across the Palaeocene-Eocene (P-E) transition. Unlike in the open oceans, the Tethys exhibits a gradual decrease of 1.5% in δ13C values prior to the rapid δ13C excursion. Associated with the 613C excursion is a decrease in calcite burial, increase in detrital content and appearance of a unique opportunistic planktic foraminifera1 assemblage (e.g. compressed acarininids). The existence of a prelude decrease in δ13C values in the Tethys suggests that the P-E δ13C excursion may have occurred in two steps and over a few hundred thousand years, rather than as one step over a few thousand years as previously suggested. This slower excursion rate is readily explained by changing organic carbon weathering or burial rates and avoids the need of invoking ad hoc scenarios.

URLhttp://onlinelibrary.wiley.com/doi/10.1111/j.1365-3121.1996.tb00567.x/abstract
DOI10.1111/j.1365-3121.1996.tb00567.x

Ecological stasis and saltation: species richness change in planktic foraminifera during the late Paleocene to early Eocene, (DSDP) Site 577

TitleEcological stasis and saltation: species richness change in planktic foraminifera during the late Paleocene to early Eocene, (DSDP) Site 577
Publication TypeJournal Article
Year of Publication1995
AuthorsLu, G, Keller, G
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume117
Pagination211–227
Date Publishedsep
Abstract

A high resolution study of late Paleocene to early Eocene planktic foraminifera at DSDP Site 577 indicates the presence of three rapid faunal turnovers, or saltation events, with durations varying between 200–400 kyr and species turnover rates between 4–12 species/100 kyr. These saltation events are separated by slow faunal turnovers, or stasis intervals, with durations varying between 2.56–5.21 Myr and species turnover rates between 0.6–1.8 species/100 kyr. Each saltation event has different characteristics with disappearances equal to appearances in event T1, appearances dominate in event T2 that nearly double species richness, and primarily disappearances in event T3 that nearly halve species richness. Only event T2 near the PE boundary is associated with major and sudden environmental changes, as marked by a rapid warming in the deep ocean and high-latitude surface ocean and a negative excursion in carbonate δ13C values, that suggest a cause-effect relationship. The other two events occur during intervals of gradual environmental changes. We suggest that all three faunal events are triggered by the attainment of threshold conditions during the oceanic environmental changes. Threshold conditions may be attained through rapid environmental changes as in the case of event T2 near the PE boundary, or by gradual though cumulative environmental changes as appears to be the case in events T1 and T3. It is unclear, however, which environmental factors (e.g., temperature, salinity, nutrients, water-mass stratification) force rapid faunal turnovers or what role intrinsic biotic factors play.   PDF

URLhttps://doi.org/10.1016/0031-0182(94)00125-r
DOI10.1016/0031-0182(94)00125-r

Planktic foraminiferal faunal turnovers in the subtropical Pacific during the late Paleocene to early Eocene

TitlePlanktic foraminiferal faunal turnovers in the subtropical Pacific during the late Paleocene to early Eocene
Publication TypeJournal Article
Year of Publication1995
AuthorsLu, G, Keller, G
JournalThe Journal of Foraminiferal Research
Volume25
Pagination97–116
Date Publishedapr
Abstract

Planktic foraminiferal analysis of sedimentary samples at 25-cm intervals (81 k.y.) at DSDP Site 577 provides a high resolution data base for deep-sea biostratigraphy and faunal changes during the late Paleocene to early Eocene. There are three major faunal turnovers, each of which occurred over a time period of 200 to 400 k.y., near the P3a/P3b, P6a/P6b and PSIP9 boundaries. These turnovers are characterized by rapid changes in species richness, large numbers of first and last appearances, and significant changes in the relative abundances of species. A chronological sequence of datum levels and faunal events of foraminifera tied to magnetostratigraphy provides biostratigraphic control at 1 m.y. intervals for the late Paleocene to early Eocene, with faunal and isotopic events near the PaleoceneiEocene boundary providing isochronous stratigraphic markers.   PDF

URLhttps://doi.org/10.2113/gsjfr.25.2.97
DOI10.2113/gsjfr.25.2.97

Planktic foraminiferal turnover and δ13C isotopes across the Paleocene-Eocene transition at Caravaca and Zumaya, Spain

TitlePlanktic foraminiferal turnover and δ13C isotopes across the Paleocene-Eocene transition at Caravaca and Zumaya, Spain
Publication TypeJournal Article
Year of Publication1994
AuthorsCanudo, JI, Keller, G, Molina, E, Ortiz, N
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume114
Pagination75–100
Date Published03/1994
Abstract

Biostratigraphic and faunal analysis of planktic foraminifera and benthic foraminiferal isotopes at Zumaya and Caravaca sections in Spain indicate that Zumaya has a continuous record with high sediment accumulation rates across the Paleocene--Eocene transition whereas Caravaca has a hiatus with the uppermost Zone P4, Zone P5 and the lower part of Zone P6 missing. Both sections contain nearly continuous and expanded records of the global δ13C excursion at Zumaya and Caravaca respectively. The δ13C excursion is associated with dark grey shale deposition in a dysaerobic benthic environment. This δ13C event is associated with a major planktic foraminiferal turnover marked by the gradual extinction and evolution of 33% and 18% of the species respectively. A rapid change in the relative abundances of these taxa occurs at the δ13C excursion coincident with the extinction of 50% of the small benthic foraminiferal taxa. The entire water column was affected by this faunal turnover (surface, intermediate, deep dwellers), but in contrast to benthic foraminifera there was no net loss of habitats since species extinctions of planktic foraminifera were largely replaced by originations. PDF

URLhttps://doi.org/10.1016/0031-0182(95)00073-u
DOI10.1016/0031-0182(95)00073-u

The Paleocene-Eocene transition in the Antarctic Indian Ocean: Inference from planktic foraminifera

TitleThe Paleocene-Eocene transition in the Antarctic Indian Ocean: Inference from planktic foraminifera
Publication TypeJournal Article
Year of Publication1993
AuthorsLu, G, Keller, G
JournalMarine Micropaleontology
Volume21
Pagination101–142
Date Publishedapr
Abstract

 

Isotopic depth stratification and relative abundance studies of planktic foraminifera at ODP Site 738 reveal three major faunal turnovers during the latest Paleocene and early Eocene, reflecting the climatic and structural changes in the Antarctic surface ocean.

Faunal Event 1 occurred near the Paleocene/Eocene boundary and is characterized by a faunal turnover in deep dwellers, decreased relative abundance in intermediate dwellers and increased relative abundance in surface dwellers. This event marks a temporary elimination of the vertical structure in the surface ocean over a period of more than 63,000 years that is apparently associated with the sudden shutdown of the “Antarctic Intermediate Water” production. The appearance of morozovellids before this event suggests that polar warming is the cause for the shutdown in the production of this water mass. At this time warm saline deep water may have formed at low latitudes.

Faunal Event 2 occurred near the AP5a/AP5b Subzonal boundary and is characterized by a faunal turnover in deep dwellers with no apparent change in surface and intermediate dwellers. Increased individual size, wall-thickness and relative abundance in deep dwelling chiloguembelinids suggests the formation of a deep oxygen minima in the Antarctic Oceans during the maximum polar warming possibly as a result of upwelling of nutrient-rich deep water.

Faunal Event 3 occurred in Subzone AP6 and is characterized by a faunal turnover in surface dwellers and a delayed diversification in deep dwellers. This event marks the onset of Antarctic cooling. A drastic decrease in the δ13C/δ18O values of the deep assemblage in Zone AP7 suggests an intensified thermocline and reduced upwelling following the polar cooling.  PDF

URLhttps://doi.org/10.1016/0377-8398(93)90012-m
DOI10.1016/0377-8398(93)90012-m

Eocene-Oligocene Faunal Turnover and Antarctic Glaciation

TitleEocene-Oligocene Faunal Turnover and Antarctic Glaciation
Publication TypeBook Chapter
Year of Publication1992
AuthorsKeller, G, MacLeod, N
Pagination218-244
PublisherPrinceton University Press
CityPrinceton
Abstract

Low-latitude planktic foraminiferal populations experienced a major faunal turnover between the late middle to early late Oligocene. This faunal turnover involved over 80% of planktic foraminiferal species and took place quasi-continuously over an interval of approximately 14 m.y. The overwhelming majority of species becoming extinct during this interval were surface-dwelling forms that were ecologically replaced by more cold-tolerant subsurface-dwelling species as the thermal contrast between surface and subsurface (> 400 m) marine pelagic habitats diminished. Within this 14 m.y. interval of widespread ecological reorganization of the planktic foraminiferal faunas, two subintervals stand out as being characterized by brief, but markedly intensified turnover; these are the middle/late Eocene and the early/late Oligocene. Contrary to previous reports, there was no major faunal change across the Eocene/Oligocene (E/O) boundary. Stable isotope records and glacio-marine sediments from high latitude southern ocean ODP Legs 113 and 119 provide evidence of major glaciation on East Antarctica during the late middle to late Eocene and early Oligocene with glaciation persisting into the late Oligocene. Carbon and oxygen isotopic gradients for planktic and benthic foraminiferal species reflect decreasing surface productivity and thermal stratification during this time. The remarkably close correspondence between these stable isotope records and planktic foraminiferal turnovers strongly suggests that changes in climate and productivity were the primary driving forces behind the gradual decline and eventual extinction of the Eocene planktic foraminiferal fauna.  PDF

URLhttp://www.jstor.org/stable/j.ctt7zvp65.16?seq=1#page_scan_tab_contents

Faunal turnover and depth stratification: their relationship to climate and productivity events in the Eocene to Miocene pelagic realm

TitleFaunal turnover and depth stratification: their relationship to climate and productivity events in the Eocene to Miocene pelagic realm
Publication TypeBook Chapter
Year of Publication1992
AuthorsGerta, K, MacLeod, N
Book TitleIn Centenary of Japanese Micropaleontology, K. Ishizaki and T. Saito eds
Pagination1–14
PublisherTerra Scientific Publishing Company
CityTokyo
Abstract

A new approach to the study of evolution based on quantitative faunal analysis and the spatial distribution of taxa in the oceanic water column is presented. Middle Eocene to Miocene planktonic foraminiferal turnovers have been examined based on the numerical abundances of species and their relative depth habitat as inferred from oxygen isotope ranking of species. Results indicate that most turnovers occurs in the surface and intermediate water faunas, that all but one of the faunal turnovers coincide with accelerated global cooling, and that all faunal turnovers occur during intervals of increased productivity in the δ13C record. This apparent correlation implies that faunal turnover dynamics are mediated by intrinsic changes in the thermal structure of the oceanic surface waters over time. Nevertheless, there is no obvious linkage of specific environmental parameters to the proliferation or decline of specific faunal elements. The incorporation of these types of data into the story of the evolution of the planktonic foraminiferal fauna promises to yield new insights into the nature of both biotic and abiotic factors that have played a role in the origin and maintenance of planktonic foraminiferal diversity.

URLhttp://www.terrapub.co.jp/e-library/cjm/index.html
Original PublicationIn Centenary of Japanese Micropaleontology, K. Ishizaki and T. Saito eds

Faunal turnover and depth stratification: Their relationships to climate and productivity events in the Eocene to Miocene pelagic realm - Internet

TitleFaunal turnover and depth stratification: Their relationships to climate and productivity events in the Eocene to Miocene pelagic realm - Internet
Publication TypeBook Chapter
Year of Publication1991
AuthorsKeller, G, MacLeod, N
Book TitleIn Centenary of Japanese Micropaleontology, K. Ishizaki and T. Saito eds
PublisherTerra Scientific Publishing Company
CityToyoto
Abstract

A new approach to the study of evolution based on quantitative faunal analysis and the spatial distribution of taxa in the oceanic water column is presented. Middle Eocene to Miocene planktonic foraminiferal turnovers have been examined based on the numerical abundances of species and their relative depth habitat as inferred from oxygen isotope ranking of species. Results indicate that most turnovers occurs in the surface and intermediate water faunas, that all but one of the faunal turnovers coincide with accelerated global cooling, and that all faunal turnovers occur during intervals of increased productivity in the δ13C record. This apparent correlation implies that faunal turnover dynamics are mediated by intrinsic changes in the thermal structure of the oceanic surface waters over time. Nevertheless, there is no obvious linkage of specific environmental parameters to the proliferation or decline of specific faunal elements. The incorporation of these types of data into the story of the evolution of the planktonic foraminiferal fauna promises to yield new insights into the nature of both biotic and abiotic factors that have played a role in the origin and maintenance of planktonic foraminiferal diversity.  PDF

URLhttp://www.terrapub.co.jp/e-library/cjm/index.html
Original PublicationIn Centenary of Japanese Micropaleontology, K. Ishizaki and T. Saito eds

Paleoenvironment of the Eastern Tethys in the Early Paleocene

TitlePaleoenvironment of the Eastern Tethys in the Early Paleocene
Publication TypeJournal Article
Year of Publication1991
AuthorsKeller, G, Benjamini, C
Journal{PALAIOS}
Volume6
Pagination439
Date Published10/1991
Abstract

In the earliest Paleocene at least three intervals of erosion or nondeposition of sediments have been identified (K/T, P0/P1a, P1a/P1b boundaries) in addition to a black pyrite- and organic-rich clay layer about 1.5 to 3.0 m above the K/T boundary (Subzone P1b/P1c, upper Chron 29N). These hiatuses appear to be widespread and correlate with global sea level fluctuations. Danian planktic foraminiferal assemblages of the eastern Tethys are dominated by alternating abundance maxima between triserial (Guembelitria) and biserial (Woodringina, Chiloguembelina) species. Biogeographic distribution of these taxa indicates that both groups thrived in shallow continental shelf regions. Moreover, abundance maxima of triserial taxa seem to correspond to δ 13C depletion intervals, which indicate low surface productivity, whereas abundance maxima of biserial taxa correspond to enriched δ 13C intervals which imply high surface productivity. -from Authors.  PDF

URLhttps://doi.org/10.2307/3514984
DOI10.2307/3514984

Progenesis in Late Eocene populations of Subbotina linaperta (Foraminifera) from the western Atlantic

TitleProgenesis in Late Eocene populations of Subbotina linaperta (Foraminifera) from the western Atlantic
Publication TypeJournal Article
Year of Publication1990
AuthorsMacLeod, N, Keller, G, Kitchell, JA
JournalMarine Micropaleontology
Volume16
Pagination219–240
Date Published11/1990
Abstract

It has been argued that the successive appearance of a distinct set of test morphologies by planktic foraminifera represents evidence for the multiple evolution of mechanical optima (Steineck and Fleisher, 1978). However, morphometric, isotopic and biostratigraphic analyses of the globigerine species Subbotina linaperta from Middle-Late Eocene Atlantic Ocean deep sea cores suggests that changes in developmental pathways may also play an important role in planktic foraminiferal evolution. During a period of prolonged and global change in the Middle-Late Eocene marine environment, at least one western Atlantic population ofS. linaperta was characterized by a marked decrease in mean test size that persisted throughout the remainder of this species' teilzone. In addition, this Late Eocene population exhibited anomalous relative abundances and a pronounced change in depth habitat when compared to conspecific populations in the Gulf of Mexico and South Atlantic. Quantitative morphometric analyses indicate the observed size reduction to be a secondary result of selection for the ontogenetically accelerated attainment of sexual maturity; a mode of developmentally mediated evolution termed progenesis. The temporal persistence of this progenetically dwarfed population throughout the remainder of the Late Eocene at this locality serves to illustrate the potential of this evolutionary mechanism to produce sustained morphological and ecological changes within populations of marine plankton as well as implying that this population was at least partially isolated from the general circulation of the Gulf Stream during this time interval. In addition, similarities between the nature of phenotypic change in this population and the common anecdotal observation of test size reduction in a number of planktic foraminiferal lineages at the Cretaceous-Tertiary boundary and during the Paleogene-Neogene faunal transition suggest that selection for different developmental patterns may provide an alternative explanation for the reappearance of simple globigerine morphotypes after major planktic foraminiferal extinction events.  PDF

URLhttps://doi.org/10.1016/0377-8398(90)90005-7
DOI10.1016/0377-8398(90)90005-7

Late Eocene to Oligocene Events: Molino de Cobo, Betic Cordillera, Spain.

TitleLate Eocene to Oligocene Events: Molino de Cobo, Betic Cordillera, Spain.
Publication TypeJournal Article
Year of Publication1989
AuthorsMolina, E, Keller, G, Madile, N
JournalLate Eocene to Oligocene Events: Molino de Cobo, Betic Cordillera, Spain.
Volume20
Issue3
Start Page491-514
Abstract

Quantitative analysis of upper Eocene to Oligocene planktonic foraminifers and calcareous nannofossils in the Molino de Cobo section, Betic Cordillera, Spain indicate three major extinction evenLS: 1) in the upper Eocene at the extinction of Globigerapsis index, 2) at the Eocene-Oligocene boundary and 3) al tbe lower/upper Oligocene boundary. The Globigerapsis index extinction event in Ibis area coincides with the dramatic abundance decline of the discshaped discoasters (D. saipanensis, D. barbadiensis). This faunal and floral assemblage change coincides with a carbonate dissolution interval. The Eocene-Oligocene boundary extinction event involves five planktonic foraminiferal species, which contrary to common belief did not go extinct simulta~ neously, but stretched out over a 3m intervalo This extinction event is probably related to the isotopic enrichment that signals the development of the psychrosphere, or two layer ocean with cold bottom and warm surface water. The lower/upper O1igocene faunal tumover event involves the extinction of surviving Eocene species and the evolulion of late Oligocene to Miocene species. A short hiatos may be present at this intervalo This faunal turnover is most likely related to global cooling and a major sea level drop.   PDF

URLhttp://wzar.unizar.es/perso/emolina/pdf/Molina1988REM.pdf

Late Eocene Crystal-Bearing Spherules: Two Layers or One? A Reply to the Critique by B. P. Glass and C. A. Burns

TitleLate Eocene Crystal-Bearing Spherules: Two Layers or One? A Reply to the Critique by B. P. Glass and C. A. Burns
Publication TypeJournal Article
Year of Publication1988
AuthorsKeller, G, D'Hondt, S
JournalMeteoritics
Volume23
Pagination167–169
Date Published06/1988
URLhttps://doi.org/10.1111/j.1945-5100.1988.tb00912.x
DOI10.1111/j.1945-5100.1988.tb00912.x

Late Eocene Impact Microspherules: Stratigraphy, age and Geochemistry

TitleLate Eocene Impact Microspherules: Stratigraphy, age and Geochemistry
Publication TypeJournal Article
Year of Publication1987
AuthorsKeller, G, D'Hondt, SL, Orth, CJ, Gilmore, JS, Oliver, PQ, Shoemaker, EM, Molina, E
JournalMeteoritics
Volume22
Pagination25–60
Date Published03/1987
Abstract

Recent discoveries of microtektite and related crystal bearing microspherule layers in deep-sea sediments of the west equatorial Pacific DSDP Sites 292, 315A and 462, off-shore New Jersey in Site 612 and in southern Spain have confirmed the presence of at least three microspherule layers in Late Eocene sediments. Moreover, these discoveries have extended the North American strewn field from the Caribbean and Gulf of Mexico region to the northwest Atlantic, and have established a third strewn field in western equatorial Pacific and Indian Ocean which may extend to the Mediterranean.   PDF

URLhttps://doi.org/10.1111/j.1945-5100.1987.tb00883.x
DOI10.1111/j.1945-5100.1987.tb00883.x

Major element compositional variation within and between Different late Eocene Microtektite strewn fields

TitleMajor element compositional variation within and between Different late Eocene Microtektite strewn fields
Publication TypeJournal Article
Year of Publication1987
AuthorsD'Hondt, SL, Keller, G, Stallard, RF
JournalMeteoritics
Volume22
Pagination61–79
Date Published03/1987
Abstract

Major element compositional overlap exists between microspherules of different microtektite layers or strewnfields. For this reason, microspherules of similar composition cannot, a priori, be assumed to belong to the same microtektite event and those of different compositions cannot, a priori, be assumed to result from different events. Nevertheless, despite major element compositional overlap between microspherules of different strewnfields, multivariate factor analysis shows microtektites and related microspherules of three stratigraphically different late Eocene layers to follow recognizably different compositional trends.   PDF

URLhttps://doi.org/10.1111/j.1945-5100.1987.tb00884.x
DOI10.1111/j.1945-5100.1987.tb00884.x

Global distribution of late Paleogene hiatuses

TitleGlobal distribution of late Paleogene hiatuses
Publication TypeJournal Article
Year of Publication1987
AuthorsKeller, G, Herbert, T, Dorsey, R, D\textquotesingleHONDT, S, Johnsson, M, Chi, WR
JournalGeology
Volume15
Pagination199
Abstract

Six global late Paleogene hiatuses (PHa to PHe) have been identified from deep-sea sequences. These hiatuses occurred at the middle/late Eocene boundary, late Eocene, Eocene/Oligocene boundary, late early Oligocene, late Oligocene, and Oligocene/Miocene boundary horizons.

Paleodepth distribution of hiatuses shows hiatus maxima characterized by major mechanical erosion below 4800 m, at mid-depth between 2000 and 3000 m, and in shallower water above 1600 m paleodepth. The geographic distribution and paleodepth of these hiatus maxima suggest that flow paths of major water masses and currents are the principal cause. Widespread short hiatuses due to carbonate dissolution or nondeposition occurred primarily during global cooling trends or climatic instability and appear to correlate to sea-level transgressions or onlap sequences. These hiatuses may have been caused by basin-shelf fractionation of carbonates.   PDF

URLhttps://doi.org/10.1130/0091-7613(1987)15<199:gdolph>2.0.co;2
DOI10.1130/0091-7613(1987)15<199:gdolph>2.0.co;2

Eocene-Oligocene Boundary Reference Sections in the Pacific

TitleEocene-Oligocene Boundary Reference Sections in the Pacific
Publication TypeBook Chapter
Year of Publication1986
AuthorsKeller, G
Book TitleDevelopments in Palaeontology and Stratigraphy
Pagination209–212
PublisherElsevier
Abstract

This chapter discusses Eocene–Oligocene boundary reference sections in the Pacific. In over 15 years of deep-sea drilling the Eocene–Oligocene boundary was recovered in relatively few deep sea drilling project (DSDP) sites in the Pacific Ocean located primarily in the equatorial region and the Southwest Pacific. The differences in species ranges clearly indicate the necessity for separate high and low latitude reference sections and a means of calibrating them independent of microfossils that is possible for the Eocene–Oligocene boundary by using the oxygen isotope record. Thus, based on core recovery fossil preservation, biostratigraphic, and stable isotope studies sites 292 and 592 represent the best candidates for the Eocene–Oligocene reference sections to date for the equatorial and Southwest Pacific.

URLhttps://doi.org/10.1016/s0920-5446(08)70123-7
DOI10.1016/s0920-5446(08)70123-7

Cenozoic migration of Alaskan terranes indicated by paleontologic study

TitleCenozoic migration of Alaskan terranes indicated by paleontologic study
Publication TypeJournal Article
Year of Publication1985
Authorsvon Huene, R, Keller, G
JournalAAPG Special Publication
Pagination121-136
Abstract

Comparison s o f microfossils fro m deep-sea cores, fro m sample s o f an explorator y drill hole, and fro m dredged rocks o f the Gulf o f Alaska, with coeval microfossil assemblage s on the Nort h America n continent, provide constraints on the northwar d migratio n o f the Yakuta t block and the Princ e William terran e during Tertiary time. The estimated paleolatitudes of microfauna and flora indicate that: (1 ) the Prince William terran e wa s attache d to North Americ a in its present position by middl e Eocen e time (40 to 42 Ma) , consistent with models derived fro m paleomagneti c data , and (2) the adjacent Yakuta t block was 30 ± 5 ° south o f its present position in earl y Eocen e (50 Ma) , 20 ± 5 ° south in middl e Eocen e (40 to 44 Ma) , and 15 ± 5 ° south in lat e Eocen e tim e (37 to 40 Ma) , thus requiring a northwar d motion o f about 30 ° since 50 Ma . Moreover , the Yakuta t block wa s at least 10° south o f the Princ e William terran e during Eocen e time . Thes e dat a ar e consistent with migratio n o f the Yakuta t block with the Pacifi c and Kul a plate s for a t least the last 50 Ma . T h e collision o f the Yakuta t block with Nort h Americ a resulted in subduction o f the block coincident with uplift o f the Kena i Mountains. Th e extension o f the Kena i Mountains into the Kodiak are a suggests tha t a southwest extension o f the Yakuta t block collided with the Kodiak margi n and was completely subducted. Th e subducted extension o f the Yakuta t block could have connected the now subducting head o f Zodiak deep-sea fan to a Nort h America n sourc e o f sediment during deposition o f the fan.  PDF

URLhttp://archives.datapages.com/data/circ_pac/1/121_b.htm

Planktonic Foraminiferal Biostratigraphy of the Middle America Trench Region, Deep Sea Drilling Project Leg 84

TitlePlanktonic Foraminiferal Biostratigraphy of the Middle America Trench Region, Deep Sea Drilling Project Leg 84
Publication TypeBook Chapter
Year of Publication1985
AuthorsStone, SM, Keller, G
Book TitleInitial Reports of the Deep Sea Drilling Project
PublisherU.S. Government Printing Office
Abstract

Eleven holes were drilled at six sites along a transect of the landward side of the Middle America Trench during DSDP Leg 84. Sites 566-570 are in the same area as DSDP Leg 67 sites offshore from Guatemala, and Site 565 is offshore from Costa Rica. Pleistocene and Pliocene sediments were recovered at Site 565; Pleistocene to upper Miocene sediments at Site 566; Pleistocene and Pliocene, lower Miocene, and Upper Cretaceous sediments at Site 567; Quaternary and middle and lower Miocene sediments at Site 568; Quaternary, lower Pliocene, middle Miocene to upper Oligocene, lower Oligocene and upper Eocene, and middle and lower Eocene sediments at Site 569; and Quaternary to middle Miocene and lower Eocene sediments at Site 570. Planktonic foraminifers are variably preserved but generally common in all holes, except within several highly dissolved intervals. Both quantitative and semiquantitative analyses of planktonic foraminifers, in addition to the first and last occurrences of index species, were used to establish the biostratigraphy for Leg 84 sites. Biostratigraphic analysis of the planktonic foraminifers provides useful data for reconstructing the tectonostratigraphic history of the southern Guatemalan segment of the Middle America Trench. The Leg 84 stratigraphic record is fragmentary. The poorly represented Paleogene section is interrupted by several unconformities, and one major Neogene unconformity occurs between the upper lower Miocene and the upper Pliocene. The Neogene unconformity can be related to tectonic activity in the Middle America Trench region associated with a major pulse in volcanic activity between 1 and 4 Ma (peaking from 1 to 2 Ma) and a minor pulse between 14 and 16 Ma. Despite the fragmentary nature of the sedimentary record, the sequences are not repeated or reversed, and evidence of imbrication of oceanic sequences is lacking. Gravity-induced downslope transport and reworking of older sediments into younger deposits, however, are apparent through analysis of benthic and planktonic foraminifers, suggesting that a slope-trench environment similar to the present one existed during the Cenozoic.  PDF

URLhttps://doi.org/10.2973/dsdp.proc.84.110.1985
DOI10.2973/dsdp.proc.84.110.1985

Comments and Replies on “Model for the origin of the Yakutat block, an accreting terrane in the northern Gulf of Alaska”

TitleComments and Replies on “Model for the origin of the Yakutat block, an accreting terrane in the northern Gulf of Alaska”
Publication TypeJournal Article
Year of Publication1984
AuthorsBruns, TR, Keller, G
JournalGeology
Volume12
Pagination565
Abstract

Wolfe and McCoy assert that Bruns's (1983a) model for the northward migration of the Yakutat block is not supported by foraminiferal or molluscan evidence and is contradicted by paleobotanical evidence. Contrary to this claim, both planktonic and benthic foraminiferal data are consistent with Bruns's model and provide temporal constraints on the northward migration of the Yakutat block, Prince William terrane, and Pacific plate between late early Eocene (50 Ma) and late Eocene to early Oligocene (38-34 Ma; Keller et al., 1984). Our foraminiferal evidence is based on detailed study of material from DSDP cores (Sites 192,183, 178), an exploratory drill hole (Middleton Island Well), dredged rocks from the Gulf of Alaska, and comparison with onshore coeval sediment sequences from California, Oregon, and Washington. We are not aware of a comparable geographic coverage of mollusca or paleobotanical data from well-dated rocks. Wolfe and McCoy have compared our GEOLOGY, September 1984 565 microfossil assemblages with molluscan and floral assemblages that are not coeval, and they try to correlate continental paleoclimates with oceanic paleoenvironments. Even worse, however, is the uncertainty in their dating, which in some cases spans the time during which the Yakutat block would have traveled through one climatic zone and well into another.  PDF

URLhttps://doi.org/10.1130/0091-7613(1984)12<565:caromf>2.0.co;2
DOI10.1130/0091-7613(1984)12<565:caromf>2.0.co;2

Multiple Microtektite Horizons in Upper Eocene Marine Sediments? -Reply

TitleMultiple Microtektite Horizons in Upper Eocene Marine Sediments? -Reply
Publication TypeJournal Article
Year of Publication1984
AuthorsKeller, G, D'Hondt, S, Vallier, TL
JournalScience
Volume224
Pagination309–310
Date Published04/1984
Abstract

Keller et al. recently suggested (1) that there are several middle Eocene to middle Oligocene microtektite horizons and implied that these horizons indicate separate tektite events. Although there is no a priori reason why there could not be multiple tektite events during this period, Keller et al. do not provide any descriptive, petrographic, or compositional data to support their identification of microtektites from previously unreported stratigraphic layers. Furthermore, the lack of data on abundance versus depth and of compositional data does not allow the reader to decide if the microtektite occurrences are due to several events, as Keller et al. claim, or merely to one event with scattered younger occurrences attributable to reworking.  PDF

URLhttps://doi.org/10.1126/science.224.4646.309-a
DOI10.1126/science.224.4646.309-a

The Eocene/Oligocene Boundary Event in the Deep Sea

TitleThe Eocene/Oligocene Boundary Event in the Deep Sea
Publication TypeJournal Article
Year of Publication1984
AuthorsCorliss, BH, Aubry, M-P, Berggren, WA, Fenner, JM, Keigwin, LD, Keller, G
JournalScience
Volume226
Pagination806–810
Date Published11/1984
Abstract

Analysis of middle Eocene to early, Oligocene calcareous and siliceous microfossils shows gradual biotic changes with no massive extinction event across the Eocene/Oligocene boundary. Biotic changes in the late Paleogene appear to reflect changing paleoclimatic and paleoceanographic conditions and do not support suggestions of a catastrophic biotic event caused by a bolide impact at the Eocenel Oligocene boundary.

URLhttps://doi.org/10.1126/science.226.4676.806
DOI10.1126/science.226.4676.806

Multiple Microtektite Horizons in Upper Eocene Marine Sediments: No Evidence for Mass Extinctions

TitleMultiple Microtektite Horizons in Upper Eocene Marine Sediments: No Evidence for Mass Extinctions
Publication TypeJournal Article
Year of Publication1983
AuthorsKeller, G, D'Hondt, SL, Vallier, TL
JournalScience
Volume221
Pagination150–152
Date Published07/1983
Abstract

Microtektites have been recovered from three horizons in eight middle Eocene to middle Oligocene marine sediment sequences. Five of these occurrences are coeval and of latest Eocene age (37.5 to 38.0 million years ago); three are coeval and of early late Eocene age (38.5 to 39.5 million years ago); and three are of middle Oligocene age (31 to 32 million years ago). In addition, rare probable microtektites have been found in sediments with ages of about 36.0 to 36.5 million years. The microtektite horizon at 37.5 to 38.0 million years can be correlated with the North American tektite-strewn field, which has a fission track age (minimum) of 34 to 35 million years and a paleomagnetic age of 37.5 to 38.0 million years. There is no evidence for mass faunal extinctions at any of the microtektite horizons. Many of the distinct faunal changes that occurred in the middle Eocene to middle Oligocene can be related to the formation of the Antarctic ice sheet and the associated cooling phenomena and intensification of bottom currents that led to large-scale dissolution of calcium carbonate and erosion, which created areally extensive hiatuses in the deep-sea sediment records. The occurrence of microtektite horizons of several ages and the lack of evidence for faunal extinctions suggest that the effects of extraterrestrial bolide impacts may be unimportant in the biologic realm during middle Eocene to middle Oligocene time.

URLhttps://doi.org/10.1126/science.221.4606.150
DOI10.1126/science.221.4606.150