Correlation between hydrogen isotope ratios of lipid biomarkers and sediment maturity
Correlation between hydrogen isotope ratios of lipid biomarkers and sediment maturity
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DOI：
10.1016/j.gca.2005.07.014
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发表时间：
2005-12
影响因子：
5
通讯作者：
J. Radke;A. Bechtel;R. Gaupp;W. Püttmann;L. Schwark;D. Sachse;G. Gleixner
中科院分区：
文献类型：
--
作者：
J. Radke;A. Bechtel;R. Gaupp;W. Püttmann;L. Schwark;D. Sachse;G. Gleixner
我们研究了热成熟度对沉积烃氢同位素比值的影响，以证明烃的同位素比值反映了古气候特征。研究了两个不同成熟历史的沉积剖面（Kupferenchafer [KS]，258 Ma和Posidonienchafer [PS]，184 Ma）的正构烷烃和非环类异戊二烯的δD值。两者都涵盖了从0.48到1.3 Rc的热成熟度（镜质体反射率和从MPI 1计算的反射率）。沉积物埋藏4500米造成的热成熟的有机质在KS层从早期Zechstein盆地的波兰，而接触变质热成熟起源于早期Toarcian PS（Posidonienenchaefer）的北德国弗洛托地块。正构烷烃的δD值与KS（y = 56‰ × MPI 1 [x] − 160‰ [VSMOW]）和PS（y = 104‰ × MPI 1 [x] − 200‰ [VSMOW]）的热成熟度呈正相关。类异戊二烯的δD值（即，降植烷、植烷）随着成熟度的增加而更加富集（KS中y = 179‰ × MPI 1 [x] − 341‰ [VSMOW]; PS中y = 300‰ × MPI 1 [x] − 415‰ [VSMOW]）。这些结果解释了为什么成熟沉积物中正构烷烃和类异戊二烯的同位素比值普遍富集D，而不存在预期的190‰的正构烷烃和类异戊二烯同位素比值差。沉积物成熟度参数与δD值的相关性表明，δD值校正后可用于古气候环境的重建。
We investigated the influence of thermal maturity on the hydrogen isotope ratios of sedimentary hydrocarbons to prove that the isotope ratio of hydrocarbons mirrors paleoclimate signatures. δD values from n-alkanes and acyclic isoprenoids of two sediment sections (Kupferschiefer [KS], 258 Ma, and Posidonienschiefer [PS], 184 Ma) with different maturation history were investigated. Both covered thermal maturity from 0.48 to 1.3 Rc(vitrinite reflectance and reflectance calculated from MPI1). Sediment burial up to 4500 m caused thermal maturation of organic matter in the KS horizon from the Early Zechstein basin of Poland, whereas contact metamorphic thermal maturation originated in the Early Toarcian PS (Posidonienschiefer) of the North German Vlotho Massif. The δD values of the extracted n-alkanes positively correlate with thermal maturity in the KS (y = 56‰ × MPI1[x] − 160‰ [VSMOW]) and in the PS (y = 104‰ × MPI1[x] − 200‰ [VSMOW]). The δD values of isoprenoids (i.e., pristane, phytane) were even more enriched with increasing maturity (y = 179‰ × MPI1[x] − 341‰ [VSMOW] in the KS; y = 300‰ × MPI1[x] − 415‰ [VSMOW] in PS). These results explain why isotope ratios of n-alkanes and isoprenoids in mature sediments are generally enriched in D and do not have the expected isotopic difference between n-alkanes and isoprenoids of ∼190‰. Moreover, the correlation between sediment maturity parameters and δD values suggests that after correction the δD values of n-alkanes can be used to reconstruct climate and environment in the geological past.