摘要：Nitrogen isotope (δ¹⁵N) analysis has been used to evaluate depositional redox conditions in well-preserved sedimentary systems; however, fewer N-isotope studies have been performed to reconstruct the redox conditions in lacustrine shales. In this paper, we report the δ¹⁵N data from the Upper Triassic Chang 7 Shale of the Ordos Basin, North China. Sedimentary δ¹⁵N values are significantly higher in the Chang 73 and the lower part of the Chang 72 submembers (Zone A; average = 9.4 ± 1.3‰) than in the upper part of the Chang 72 and the Chang 71 submembers (Zone B; average = 5.4 ± 1.5‰). Previous geochemical measurements (i.e., U and TOC/P) of both zones show wide redox variation, however, the average values of these redox proxies are relatively higher in Zone A than those of Zone B. Combined with lithological aspects of the Chang 7 Shale, our study suggest that Zone A was mainly deposited under suboxic bottom water conditions, whereas Zone B deposits accumulated within an oxygenated water column. Stable organic carbon isotopes (δ¹³Corg) and total nitrogen (TN) values of the two zones display little variation that could be attributed to changing organic matter sources and/or post-depositional alteration of δ¹⁵N. Thus, we suggest that variations in δ¹⁵N throughout the Chang 7 Shale primarily reflect differences in depositional redox conditions and δ¹⁵N values of the shale that can provide important details regarding the depositional history of unconventional resource plays.
© 2019 Elsevier Ltd

ISSN号：0264-8172

卷、期、页：v 109,p279-290

发表日期：2019-11-01

发表期刊名称：Mar. Pet. Geol.

参与作者：Shang, Fei

通讯作者：曹玉顺

第一作者：陈睿倩,柳广弟

论文类型：期刊论文

论文概要：陈睿倩,柳广弟,Shang, Fei,曹玉顺，Nitrogen isotope compositions of the Upper Triassic Chang 7 Shale, Ordos Basin, North China: Implications for depositional redox conditions，Mar. Pet. Geol.，2019，v 109,p279-290

论文题目：Nitrogen isotope compositions of the Upper Triassic Chang 7 Shale, Ordos Basin, North China: Implications for depositional redox conditions