Composition and Evolution of Hydrogen Isotopes of n-Akanes Generated from Anhydrous Pyrolysis of Sediments from Lake Gahai, Gannan, China,Acta Geologica Sinica-English Edition

当前位置： X-MOL 学术 › Acta Geol. Sinica Engl. Ed. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Composition and Evolution of Hydrogen Isotopes of n-Akanes Generated from Anhydrous Pyrolysis of Sediments from Lake Gahai, Gannan, China
Acta Geologica Sinica-English Edition ( IF 3.5 ) Pub Date : 2021-05-31 , DOI: 10.1111/1755-6724.14720
Yi DUAN _{1,

2} , Yingzhong WU ₃ , Lantian XING ₁ , Zhongping LI ₁ , Ting ZHANG ₁

Affiliation

To understand the thermal evolution of lacustrine sedimentary n-alkane hydrogen isotopic composition (δD), especially bacterially derived n-alkanes, anhydrous thermal simulation experiments were performed with sediments from Lake Gahai (Gannan, China). We analyzed the original and pyrolysis-generated n-alkanes and their δD values. The results showed that thermal maturity and n-alkane origins significantly affected the distribution of pyrolysis-generated n-alkanes. In immature to post-mature sediments, the bacterial-derived medium-chain n-alkanes generally had depleted δD values. The maximum difference in average δD values between the bacterial-and herbaceous plant-derived medium-chain n-alkanes was 32‰, and the maximum difference in δD values among individual n-alkanes was 59‰. We found that the average δD value of pyrolysis-generated n-alkanes from different latitude was significantly different in immature to highly mature sediments, but similar in post-mature ssediments. The hydrogen isotopes of sedimentary n-alkanes can be used as indicators for paleoclimate/paleo-environment conditions only when sediments are immature to highly mature. During thermal evolution, the δD value of generated individual n-alkanes and the average δD value increased with thermal maturity, indicating that hydrogen isotopes of sedimentary n-alkanes can be used as an index of organic matter maturity. We established mathematical models of average δD values of generated n-alkanes from immature to post-mature sediments using nC₂₁^−-/nC₂₁⁺ and average chain lengths. These results improve our understanding of the distribution and δD value of sedimentary n-alkanes derived from herbaceous plants in mid-latitude plateau cold regions.

更新日期：2021-05-31

点击分享查看原文

点击收藏

阅读更多本刊最新论文本刊介绍/投稿指南11