δD values of n-alkanes in sediments from Gahai Lake, Gannan, China: implications for sources of organic matter

Duan, Yi; Zhao, Yang; Wu, Yadong; He, Jianxin; Xu, Li; Zhang, Xiaoli; Ma, Lanhua; Qian, Raorong

doi:10.1007/s10933-016-9895-1

Cited by 12 publications

(11 citation statements)

References 47 publications

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“…3b), with the value in Gh-D being lower than that in Gh-D except at 350°C. These data indicate that the distribution of bacterium-derived medium -chain n-alkanes and their thermal evolution should be considered when studying organic matter sources, maturity, and paleoclimate using nC 25 − /nC 25 + ratio and ACL value of sedimentary n-alkanes (Cranwell, 1987;Poynter et al, 1989;Simoneit et al, 1991;Duan et al, 2009bDuan et al, , 2011Duan et al, , 2016Duan and Xu, 2012;Tipple and Pagani, 2013). With increasing maturity, the CPI of nalkanes in Gh-D and Gh-G decreased (Fig.…”

Section: Effect Of Thermal Maturity On the N-alkane Compositionmentioning

confidence: 83%

“…The background information of Gahai Lake in Gannan region, China was previously reported by Duan et al (2016). In short, the Gahai Lake is located in the northeastern of the Qinghai-Tibet Plateau (Fig.…”

Section: Background Of the Study Sitementioning

confidence: 93%

“…Different geographic locations, climatic and environmental conditions play decisive roles in the sedimentary n-alkane δD value. n-Alkanes deposited in high latitude cold regions have a relatively depleted δD value, and those deposited in low-latitude tropical regions have a more enriched hydrogen isotopic composition (Sachse et al, 2006;Mügler et al 2008;Duan et al, 2014Duan et al, , 2016Duan et al, , 2019. The precursor plant type is another factor that affects the δD value of sedimentary n-alkanes.…”

Section: Introductionmentioning

confidence: 99%

“…The hydrogen isotopes of sedimentary n-alkanes have wide application potential. Studies of n-alkane hydrogen isotopes from modern and immature sediments have shown that their isotopic composition provides information on organic matter source and the paleoenvironment (e.g., Xie et al, 2000;Sauer et al, 2001;Huang et al, 2004;Sachse et al, 2004Sachse et al, , 2012Chikaraishi et al, 2005;Mügler et al 2008;Xia et al, 2008;Li et al, 2009;Seki et al, 2009;Yang et al, 2009;Duan et al, 2011Duan et al, , 2014Duan et al, , 2016Duan et al, , 2019aLu et al, 2011;Taylor et al, 2019;Yao et al, 2019). Furthermore, studies on n-alkanes hydrogen isotopes of n-alkanes in ancient sediments and crude oil can help our understanding of petroleum genesis (Li et al, 2001;Tang et al, 2005;Schimmelmann et al, 2006;Li et al, 2009;Kikuchi et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Duan et al (2019a) showed that the δD value of herbaceous plant-derived n-alkanes was more negative than n-alkanes derived from woody plants and aquatic organisms in the same sedimentary area. Additionally, a few studies have shown that n-alkanes originating from bacteria have a more depleted δD value (Chikaraishi et al, 2006;Sachse et al, 2006;Duan et al, 2016). Furthermore, diagenesis affects the δD value of sedimentary n-alkanes.…”

Section: Introductionmentioning

confidence: 99%

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Composition and Evolution of Hydrogen Isotopes ofn‐Akanes Generated from Anhydrous Pyrolysis of Sediments from Lake Gahai, Gannan, China

Duan

Xing

et al. 2021

Acta Geologica Sinica (Eng)

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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 nC 21 − / nC 21 + 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.

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