编号：CDUT-2022-15

标题：The Jenkyns Event (early Toarcian OAE) in the Ordos Basin, North China

入藏号：WOS:000579856400015

中国科学院文献情报中心期刊分区：地球科学1区/TOP

本校作者：金鑫；时志强；韩中

来源出版物：GLOBAL AND PLANETARY CHANGE  卷193 文献号 103273

出版年：2020

第一地址：成都理工大学

关键词：碳同位素；生物标志化合物；早侏罗世；湖相；孢粉地层学

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摘要：Theearly Toarcian (Early Jurassic) Oceanic Anoxic Event (T-OAE) or Jenkyns Event (~183Ma) wasmarkedbya globally synchronous negative carbon-isotope excursion, large-scale organic carbon burial and widespread oxygen depletion in the oceans. These features have been associated with volcanic activity of the Karoo and Ferrar large igneous provinces. The Jenkyns Event is well investigated in the Tethyan Ocean, but its expression incontinental settings outside of Europearestillpoorlyunderstood.Here,thelacustrineAnya(AY)sectioninthe NE Ordos Basin, North China, is studied for carbon-isotope geochemistry and palynology. Palynostratigraphy constrains the age of the section to the Pliensbachian-Toarcian transition, and a positive trend in δ13C, interrupted by a pronounced negative carbon-isotope excursion, has been identified in bulk organic matter and longchain n-alkanes. The negative excursion is the expression of the Jenkyns Event, and coincides with variable total organic carbon(TOC) content inlake sediments. Themaximum TOC (~21.5%) values precedethe most negative carbon isotopes. A turnover from spore and seed fern-dominated palynological assemblages to Classopollis superabundance is coincident with the isotopic excursion and indicates clearly environmental perturbation. Biomarker data suggest that the organic matter was mainly sourced from higher plants. The magnitude of the Toarcian excursion in the bulk organic matter of this section (~ − 12.5‰) is much larger compared to that typically observed inmarine and lake strata. Humidity-related fractionation effects in land plants and changes in plant groups might have contributed to the recorded magnitude. This magnitude is also larger than that of other terrestrial records, and casts doubt on the use of terrestrial C-isotope data to constrain deep time pCO2. Nevertheless, our findings show that the Jenkyns Event is well-recorded in lacustrine facies of the Ordos Basin.

文章链接地址：https://www.sciencedirect.com/science/article/abs/pii/S0921818120301648