Constraining the applicability of organic paleotemperature proxies for the last 90 Myrs
Constraining the applicability of organic paleotemperature proxies for the last 90 Myrs
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DOI：
10.1016/j.orggeochem.2018.12.005
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发表时间：
2019-02-01
影响因子：
3
通讯作者：
Schouten, Stefan
中科院分区：
文献类型：
--
作者：
de Bar, Marijke W.;Rampen, Sebastiaan W.;Schouten, Stefan
我们评估了过去90 Myrs中沉积在新泽西大陆架（Bass River遗址）的沉积物中长链烯烃、长链二醇和GDGTs（常用于古温学测量的脂类）分布的变化，并评估了不同祖先生成物和成岩作用对其分布的潜在影响及其对相关温度指标的影响。古近纪烯酮的分布与现代触感植物的分布大体相似，但在晚白垩世沉积物中发现了以二不饱和C-40烯酮为主的不寻常的烯酮分布，表明该时期烯酮的起源生物不同。类异戊二烯GDGT分布与现代分布相当，表明TEX86可以应用到约90 Ma。中新世长链二醇的分布与现代相似，但较老的沉积物则显示出不同寻常的分布，以C-28 1,12-和C-26 1,13-二醇为主，表明在30 Ma之前存在不同的来源生物。因此，LDI与其他古温度指标不匹配，表明其在中新世以前的沉积物中的适用性可能受到损害。我们的结果表明，在三个代理中，TEX86似乎最适用于深时温度重建。(C) 2018年作者。Elsevier Ltd.出版。
We evaluated changes in the distributions of long-chain alkenones, long-chain diols and GDGTs, lipids commonly used for paleothermometry, over the last 90 Myrs for sediments deposited on the New Jersey shelf (the Bass River site) and assessed potential effects of different ancestral producers and diagenesis on their distributions and their impact on the associated temperature proxies. As reported before, the Paleogene distributions of alkenones are generally similar to those in modern haptophytes, but unusual alkenone distributions, characterized by a dominant di-unsaturated C-40 alkenone, are observed for Late Cretaceous sediments, suggesting different ancestral source organisms for alkenones in this interval. The isoprenoid GDGT distributions remained comparable to modern-day distributions, suggesting that TEX86 can be applied up to ca. 90 Ma. The Miocene long-chain diol distributions are similar to modern-day distributions, but the older sediments reveal unusual distributions, dominated by the C-28 1,12- and C-26 1,13-diols, suggesting different source organisms before similar to 30 Ma. Accordingly, the LDI does not match other paleotemperature proxies, suggesting its applicability might be compromised for sediments older than the Miocene. Our results indicate that of the three proxies, the TEX86 seems to be the most applicable for deep time temperature reconstructions. (C) 2018 The Authors. Published by Elsevier Ltd.