Xi Chen

Xi Chen
Nanjing University | NJU · Department of Earth Science

PhD

About

21
Publications
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Publications

Publications (21)
Article
Full-text available
The diversification of metazoans during the latest Neoproterozoic and early Cambrian has been attributed to, among other factors, a progressive rise in surface oxygen levels. However, recent results have also questioned the idea of a prominent rise in atmospheric oxygen levels or a major or unidirectional shift in the marine redox landscape across...
Article
The Neoproterozoic oxygenation event (NOE) likely began earlier than 800 Ma, raising oxygen levels in the Earth’s atmosphere-ocean system and, thus, setting the stage for the emergence and diversification of animals. However, the redox history of the oceans during the following Cryogenian Period (~720-635 Ma) remains poorly constrained. Here, we pr...
Article
Full-text available
Nitrogen is an essential element for biological activity, and nitrogen isotopic compositions of geological samples record information about both marine biological processes and environmental evolution. However, only a few studies of N isotopes in the early Cambrian have been published. In this study, we analysed nitrogen isotopic compositions, as w...
Conference Paper
Nitrogen is an essential element for biological activity and nitrogen isotopes in black shale record significant information of both biological process and environmental evolution[1]. However, researches of N isotope in the early Cambrian are still sparse[3]. In this study, we use trace elements, sulphur isotopes and nitrogen isotopes of cherts, bl...
Article
Full-text available
Cryogenian Datangpo Formation was deposited during the interglacial time between the Sturtian and Marinoan ice ages. We studied nitrogen isotope compositions and contents of Mo of the black shales from the basal Datangpo Formation in northeastern Guizhou, South China, for an attempt to reconstruct the marine redox change and nitrogen cycle during t...
Article
Full-text available
The Ediacaran–Cambrian interval was an eventful transitional period, when dynamic interactions between the biosphere and its physical environment allowed the Earth System to cross into a new state, characterized by the presence of metazoans, more equable climates and more expansive oxygenation of the oceans. Due to the retreat of widespread sulphid...
Article
Full-text available
The early diversification of animals (~630 Ma), and their development into both motile and macroscopic forms (~575–565 Ma), has been linked to stepwise increases in the oxygenation of Earth’s surface environment. However, establishing such a linkage between oxygen and evolution for the later Cambrian ‘explosion' (540–520 Ma) of new, energy-sapping...
Article
The Precambrian–Cambrian boundary is claimed as one of the most crucial biological breakthroughs on our planet, when changes in chemical and physical conditions, together with key biological innovations, helped to trigger a biodiversity “explosion”. The Yangtze Platform (South China), mainly characterized by continuous and unaltered successions of...
Article
The Xiaotan section, situated on the southwestern Yangtze Platform, South China, contains an unusually expanded sedimentary record, spanning the upper Neoproterozoic to the Cambrian and representing more than 40 My of marine sedimentation. Three distinct black shale units of the Shiyantou and Yuanshan formations were analysed for redox-sensitive tr...
Article
This study reports a high-resolution carbon and strontium isotope profile for the Ediacaran–Cambrian Xiaotan section, situated in northeastern Yunnan, South China. Xiaotan section represents a more distal setting than the more condensed Meishucun section in eastern Yunnan, and is, biostratigraphically and chemostratigraphically, the best constraine...
Article
Full-text available
Isotopic compositions of Mn-carbonate and organic carbon from the same individual samples and sulfur isotopic compositions of pyrites in the basal Datangpo Formation were analyzed. Highly 34 S-enriched pyrites (d 34 S pyrite = 31.7–59.4‰) were precipitated in rel-atively occlusive pore water under anoxic condition in sediments, which is consistent...
Article
Primary carbon isotope trends in marine carbonate rocks are particularly useful for chemostratigraphic correlation and paleoenvironmental reconstruction of the Neoproterozoic Earth System. Differences, however, exist between the published carbonate C-isotope profiles from the Neoproterozoic Yangtze platform and the global C-isotope record through t...

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Projects (2)
Archived project
Investigating the Ediacaran-Cambrian transition in South China (Yangtze craton)