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Stoykova, K.
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Stoykova, K.
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- PublicationRestrictedDetailed correlation and astronomical forcing within the Upper Maastrichtian succession in the Basque Basin(2013-06)
; ; ; ; ;Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Pujalte, V.; Department of Stratigraphy and Paleontology, Fac. Science and Technology, University of the Basque Country UPV/EHU, PO Box 644, E-48080 Bilbao, Spain ;Stoykova, K.; Department of Paleontology and Stratigraphy, Geological Institute, Bulgarian Academy of Science, BG-1113 Sofia, Bulgaria ;Elorza, J.; Department of Mineralogy and Petrology, Fac. Science and Technology, University of the Basque Country UPV/EHU, PO Box 644, E-48080 Bilbao, Spain; ; ; We have undertaken a comprehensive, integrated, cyclo-magnetostratigraphic analysis and study of the calcareous nannofossils of the Upper Maastrichtian hemipelagic succession in three sections of the Basque Basin (Zumaia, Sopelana and Hendaia). The sections were correlated at bed-by-bed scale through careful analysis of the lithological stacking pattern and significant sedimentary features. For spectral analysis we used an available high-resolution carbonate proxy record spanning 64 m of section below the K/Pg (Cretaceous/Palaeogene) boundary at Zumaia containing 72 precession-related limestone-marl couplets. The continuous wavelet spectrum helped to determine and visualize the orbital forcing at both the short (~100-ky) and long (405-ky) eccentricity band. We applied bandpass Gaussian filters to the carbonate record to extract the relevant periodicities and provide a cycle-numbering scheme starting at the K/Pg boundary. The full hierarchy of precession cycles and eccentricity-related bundles is then extended toward the base of the section in question, which contains a total of 33 short eccentricity-related bundles, thus spanning more than 3 Ma. The chron C31r/C31n boundary (estimated to occur at ~3.08 Ma below the K/Pg boundary) in the lower part of the succession was determined unambiguously in all three sections studied although the C30n/C29r reversal could not be determined due to a pervasive reverse magnetization acting on the purplish lithologies in the upper part of the succession. Relevant calcareous plankton bioevents could be accurately placed on the cyclo-magnetostratigraphic template. The cyclostratigraphic framework also allowed us to estimate the duration of previously defined sea-level-related 3rd-order depositional sequences in the basin, which appear to be strongly paced by the long-term 1.2 My obliquity amplitude modulating cycle. This is an outstanding feature in the Maastrichtian greenhouse period, during which continental ice sheets are expected to be either ephemeral or non-existent. This is a matter that deserves further attention.221 32 - PublicationRestrictedThe Palaeocene ‘‘top chron C27n’’ transient greenhouse episode: evidence from marine pelagic Atlantic and peri-Tethyan sections(2012)
; ; ; ; ; ;Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Pujalte, V.; Department of Stratigraphy and Paleontology, Fac. Science and Technology, University of the Basque Country UPV⁄EHU, PO Box 644, Bilbao E-48080, Spain ;Stoykova, K.; Department of Paleontology and Stratigraphy, Geological Institute, Bulgarian Academy of Science, Sofia BG-1113, Bulgaria ;Baceta, J. I.; Department of Stratigraphy and Paleontology, Fac. Science and Technology, University of the Basque Country UPV⁄EHU, PO Box 644, Bilbao E-48080, Spain ;Ivanov, M.; Department of Geology and Paleontology, University of Sofia, Sofia BG-1000, Bulgaria; ; ; ; The early Cenozoic, which is punctuated by several negative carbon isotope excursions (CIEs), was a time of climatic and oceanographic transition from ’Greenhouse’ to ’Icehouse’ conditions. The occurrence of a 0.5& CIE starting at the top of Chron C27n (TC27N) is reconfirmed with stable isotope data from Zumaia (Spain) and Bjala (Bulgaria) localities. Spectral analysis on respective carbonate ⁄magnetic susceptibility proxy records substantiates the orbital cyclostratigraphy allowing correlation to a high-resolution benthic foraminifera isotope record from ODP Pacific Site 1209, that indicates a coeval 2 C transient warming. The hyperthermal event lasts 200 ka, contrasting with other short-lived events from the Eocene, and displays a relatively rapid onset and a longer tailing back to pre-event values similar to the Palaeocene–Eocene Thermal Maximum (PETM), though lower in amplitude. That a causal trigger for the TC27N event may be the onset of volcanism in the North Atlantic Igneous Province (NAIP) can be inferred from a 200-m-thick lava pile erupted during C27n ⁄ C26r polarity transition in the E Greenland margin.265 35 - PublicationRestrictedExtending Back the Palaeogene Astronomical Time Scale: An Integrated Analysis of the Upper Maastrichtian Strata in the Basque Basin(Springer International Publishing, 2013-07-01)
; ; ; ; ;Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Pujalte, V.; Department of Stratigraphy and Paleontology, University of the Basque Country, UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain ;Stoykova, K.; Department of Paleontology and Stratigraphy, Geological Institute, Bulgarian Academy of Science, BG-1113 Sofia, Bulgaria ;Elorza, J.; Department of Mineralogy and Petrology, University of the Basque Country, UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain; ; ; ; ; ; ; ; ;Rocha, R.; Faculdade de Ciências e Tecnologia Ciências da Terra, Universidade Nova de Lisboa ;Pais, J.; Faculdade Ciências e Tecnologia Ciencias da Terra, Universidade Nova de Lisboa ;Kullberg, J. C.; Ciências da Terra, Faculdade de Ciências e Tecnologia ;Finney, S.; Geological Sciences, California State University Long Beach; ; ; We present a comprehensive, integrated, cyclo–magnetostratigraphic analysis and study of the calcareous nannofossils of the upper Maastrichtian hemipelagic succession in three sections of the Basque Basin (Zumaia, Sopelana, and Hendaia). The sections were correlated at a bed-by-bed scale through careful analysis of the lithological stacking pattern and significant sedimentary features. For spectral analysis, we used an available carbonate proxy record spanning 64 m of section below the K–Pg (Cretaceous–Palaeogene) boundary at Zumaia containing 72 precession-related limestone–marl couplets. The continuous wavelet spectrum helped to determine and visualize the orbital forcing at both the short (~100 kyr) and long (405 kyr) eccentricity bands. We applied bandpass Gaussian filters to the carbonate record to extract the relevant periodicities and provide a cycle-numbering scheme starting at the K–Pg boundary. The full hierarchy of precession cycles and eccentricity-related bundles was then extended towards the base of the Zumaia section, which contains 33 short eccentricity-related bundles, thus spanning more than 3 Myr. The C31r–C31n chron boundary (estimated to occur at ~3.08 Myr prior to the K–Pg boundary) in the lower part of the succession was determined unambiguously in all three sections studied, although the C30n–C29r reversal could not be determined due to a pervasive reverse magnetization acting on the purplish lithologies in the upper part of the succession. Relevant calcareous plankton bioevents were able to be accurately placed on the cyclo–magnetostratigraphic template. The cyclostratigraphic framework also allowed us to estimate the duration of previously defined sea-level-related, third-order depositional sequences in the basin, which appear to be strongly paced by the long-term 1.2 Myr obliquity amplitude modulating cycle.314 97 - PublicationRestrictedHigh-resolution intra- and interbasinal correlation of the Danian–Selandian transition (Early Paleocene): The Bjala section (Bulgaria) and the Selandian GSSP at Zumaia (Spain)(2010-09-16)
; ; ; ; ; ;Dinarès-Turell, J.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Stoykova, K.; Department of Paleontology and Stratigraphy, Geological Institute, Bulgarian Academy of Science, BG-1113 Sofia, Bulgaria ;Baceta, J. I.; Department of Stratigraphy, Univ. Basque Country, PO Box 644, E-48080 Bilbao, Spain ;Ivanov, M.; Department of Geology and Paleontology, University of Sofia, BG-1000 Sofia, Bulgaria ;Pujalte, V.; Department of Stratigraphy, Univ. Basque Country, PO Box 644, E-48080 Bilbao, Spain; ; ; ; The Danian–Selandian (D–S) boundary has been identified for the first time in the Black Sea coast at Bjala (Bulgaria) based on a new integrated bio-, magneto- and cyclostratigraphic study. Several correlation criteria as established for the basal Selandian GSSP from Zumaia (Basque Basin) are evaluated. Noteworthy, is the almost complete lack of calcareous nannoplankton species Braarudosphaera bigelowi in the Bulgarian sections, a sharp decrease of which was indicated as suitable criteria for defining the D–S boundary as it occurred both at Zumaia and in the classical locations of the North Sea basin. Conversely, the second evolutionary radiation of the calcareous nannofossil genus Fasciculithus together with the occurrence of Fasciculithus tympaniformis that define the NP4/NP5 zonal boundary seem to be reliable criteria to approximate the D–S boundary. In detail, however, the best approach is to integrate biostratigraphic data within a magnetostratigraphic and/or cyclostratigraphic framework. Refinements on the placement of chron C27n at Zumaia and robust bed-by-bed correlation between several Basque sections and Bjala indicates that the D–S boundary is located 30 precession cycles (~630 ky) above C27n. In addition to the precession-related marl–limestone couplets and 100-ky eccentricity bundles recognized in the studied sections, expression of the stable 405-ky long eccentricity allows direct tuning to the astronomical solutions. A correlation of the land-based sections with previously tuned data from ODP Site1262 from the Southern Atlantic is challenged. Our choice is consistent with original tuning at Zumaia but shifts one 100-ky cycle older previous tuning from Site 1262 along the interval above C27n. Under the preferred tuning scheme the D–S boundary can be given an age of 61.641± 0.040 Ma on the La04 orbital solution.178 28