DOI: 10.1016/j.palaeo.2016.10.032
论文题名: Stable C and O isotopic study of the Campanian chalk from the Mielnik section (eastern Poland): Signals from bulk rock, belemnites, benthic foraminifera, nannofossils and microcrystalline cements
作者: Bojanowski M.J. ; Dubicka Z. ; Minoletti F. ; Olszewska-Nejbert D. ; Surowski M.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2017
卷: 465 起始页码: 193
结束页码: 211
语种: 英语
英文关键词: Carbon and oxygen isotopic composition
; Cathodoluminoscopy
; Early carbonate diagenesis
; Paleoecology
; Paleotemperature
; Strontium
; Vital isotope effects
英文摘要: Exceptionally well preserved chalk from the Mielnik section in eastern Poland has been analyzed for Sr, C and O isotope composition recorded in bulk rock samples, belemnite rostra, hand-picked benthic foraminifera and separated fine fractions (incl. calcareous nannoplankton and calcite cements). The stratigraphic δ13C and δ18O trends are consistent with the global seawater variations during the Campanian and confirm strong climatic perturbation accompanying the global sea-level fall during the uppermost Campanian. Chalk samples contain disseminated early-diagenetic microcrystalline calcite cement having δ13C and δ18O values only slightly different (by < 1‰) than those of separated nannoplankton. This cementation did not alter significantly the original bulk C and O isotopic composition of bulk chalk, which supports the applicability of isotopic analyses of chalk samples, even those containing carbonate cements, for paleoceanographic and chemostratigraphic investigations. Significant differences in δ13C and δ18O values between different constituents measured from the same levels are discernible. They are related with thermal gradients in the water column and with the habitat and vital effects of biogenic components. Benthic foraminifera reflect strong vital effects in δ13C and δ18O with a tendency to lower values than the other sample types. The minimum strength of the disequilibrium fractionation effect for δ18O during foraminiferal shell secretion is estimated up to 2‰. Belemnites show offsets in δ13C values, which are difficult to estimate, but their δ18O values appear to have recorded composition of seawater. The large difference in δ18O values between belemnites and nannoplankton or bulk material suggests that belemnites were nectobenthic organisms living close to the seafloor. The 87Sr/86Sr values and biostratigraphic position of the belemnites correspond well to those in the Lägerdorf (McArthur et al., 1993), the reference section for the European, Upper Cretaceous epicontinental marine deposits, but are not in agreement with the Campanian stratigraphy defined in the Geological Time Scale 2012 (Gradstein et al., 2012), where positions of some biostratigraphic divisions are not well calibrated against the absolute age. © 2016 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/68076
Appears in Collections: 过去全球变化的重建
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作者单位: Institute of Geological Sciences, Polish Academy of Sciences, Twarda 51/55, Warsaw, Poland; Institute of Geology, University of Warsaw, Żwirki i Wigury 93, Warsaw, Poland; Sorbonne Universités, UPMC Univ Paris 06, Institut de Sciences de la Terre de Paris (ISTeP), 4 place Jussieu, Paris, France
Recommended Citation:
Bojanowski M.J.,Dubicka Z.,Minoletti F.,et al. Stable C and O isotopic study of the Campanian chalk from the Mielnik section (eastern Poland): Signals from bulk rock, belemnites, benthic foraminifera, nannofossils and microcrystalline cements[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2017-01-01,465