GERTA KELLER TOPICAL PUBLICATIONS

Paleocene-Eocene Thermal Maximum and Eocene climate events

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

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.

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.

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

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

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

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

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