气候变化领域集成服务门户(CCPortal): Assessing the impact of diagenesis on foraminiferal geochemistry from a low latitude, shallow-water drift deposit

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DOI	10.1016/j.epsl.2020.116390
	Assessing the impact of diagenesis on foraminiferal geochemistry from a low latitude, shallow-water drift deposit
	Stainbank S.; Spezzaferri S.; De Boever E.; Bouvier A.-S.; Chilcott C.; de Leau E.S.; Foubert A.; Kunkelova T.; Pichevin L.; Raddatz J.; Rüggeberg A.; Wright J.D.; Yu S.M.; Zhang M.; Kroon D.
发表日期	2020
ISSN	0012821X
卷号	545
英文摘要	Due to their large heat and moisture storage capabilities, the tropics are fundamental in modulating both regional and global climate. Furthermore, their thermal response during past extreme warming periods, such as super interglacials, is not fully resolved. In this regard, we present high-resolution (analytical) foraminiferal geochemical (δ18O and Mg/Ca) records for the last 1800 kyr from the shallow (487 m) Inner Sea drift deposits of the Maldives archipelago in the equatorial Indian Ocean. Considering the diagenetic susceptibility of these proxies, in carbonate-rich environments, we assess the integrity of a suite of commonly used planktonic and benthic foraminifera geochemical datasets (Globigerinoides ruber (white), Globigerinita glutinata (with bulla), Pulleniatina obliquiloculata (with cortex) and Cibicides mabahethi) and their use for future paleoceanographic reconstructions. Using a combination of spot Secondary Ion Mass Spectrometer, Electron Probe Micro-Analyzer and Scanning Electron Microscope image data, it is evident that authigenic overgrowths are present on both the external and internal test (shell) surfaces, yet the degree down-core as well as the associated bias is shown to be variable across the investigated species and proxies. Given the elevated authigenic overgrowth Mg/Ca (∼12–22 mmol/mol) and δ18O values (closer to the benthic isotopic compositions) the whole-test planktonic G. ruber (w) geochemical records are notably impacted beyond ∼627.4 ka (24.7 mcd). Yet, considering the setting (i.e. bottom water location) for overgrowth formation, the benthic foraminifera δ18O record is markedly less impacted with only minor diagenetic bias beyond ∼790.0 ka (28.7 mcd). Even though only the top of the G. ruber (w) and C. mabahethi records (whole-test data) would be suitable for paleo-reconstructions of absolute values (i.e. sea surface temperature, salinity, seawater δ18O), the long-term cycles, while dampened, appear to be preserved. Furthermore, planktonic species with thicker-tests (i.e. P. obliquiloculata (w/c)) might be better suited, in comparison to thinner-test counter-parts (i.e. G. glutinata (w/b), G. ruber (w)), for traditional whole-test geochemical studies in shallow, carbonate-rich environments. A thicker test equates to a smaller overall bias from the authigenic overgrowth. Overall, if the diagenetic impact is constrained, as done in this study, these types of diagenetically altered geochemical records can still significantly contribute to studies relating to past tropical seawater temperatures, latitudinal scale ocean current shifts and South Asian Monsoon dynamics. © 2020 Elsevier B.V.
关键词	early diagenesis foraminifera IODP Mg/Ca stable isotopes tropical drift deposits
英文关键词	Deposits; Digital storage; Oceanography; Scanning electron microscopy; Seawater; Surface waters; Tropics; Benthic foraminifera; Electron probe micro analyzer; Equatorial Indian Ocean; Foraminiferal geochemistry; Geochemical datasets; Sea surface temperature (SST); Seawater temperature; Secondary ion mass spectrometers; Geochemistry; assessment method; depositional environment; diagenesis; extreme event; foraminifera; future prospect; paleoceanography; reconstruction; sediment chemistry; shallow water; Indian Ocean; Indian Ocean (Equatorial); Maldives; Cibicides; Foraminifera; Globigerinita glutinata; Globigerinoides ruber; Pulleniatina obliquiloculata
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202901
作者单位	Department of Geosciences, University of Fribourg, Chemin du Musée 6, Fribourg, 1700, Switzerland; Institute of Earth Sciences, University of Lausanne, Géopolis, Lausanne, 1015, Switzerland; School of GeoSciences, University of Edinburgh, Grant Institute, The King's Buildings, James Hutton Road, Edinburgh, EH9 3FE, United Kingdom; Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, Frankfurt, 60438, Germany; Frankfurt Isotope and Element Research Center (FIERCE), Goethe University Frankfurt, Altenhöferallee 1, Frankfurt, 60438, Germany; Department of Earth and Planetary Sciences, Rutgers, the State University of New Jersey, Bush Campus, 610 Taylor Road, Piscataway, NJ 08854-8066, United States
推荐引用方式 GB/T 7714	Stainbank S.,Spezzaferri S.,De Boever E.,et al. Assessing the impact of diagenesis on foraminiferal geochemistry from a low latitude, shallow-water drift deposit[J],2020,545.
APA	Stainbank S..,Spezzaferri S..,De Boever E..,Bouvier A.-S..,Chilcott C..,...&Kroon D..(2020).Assessing the impact of diagenesis on foraminiferal geochemistry from a low latitude, shallow-water drift deposit.Earth and Planetary Science Letters,545.
MLA	Stainbank S.,et al."Assessing the impact of diagenesis on foraminiferal geochemistry from a low latitude, shallow-water drift deposit".Earth and Planetary Science Letters 545(2020).