Relationship between the origin of organic-rich shale and geological events of the Upper Ordovician-Lower Silurian in the Upper Yangtze area

Lanyu Wu, Yongchao Lu, Shu Jiang, Xiaofeng Liu, Zhanhong Liu, Yangbo Lu

Research output: Contribution to journalArticle

Abstract

Based on detailed sedimentological observations and geochemical analyses, four geological events have been identified, and a genetic depositional model has been established within a sequence stratigraphic framework. The organic-rich siliceous shale interbedded with dense bentonite layers in the transgressive systems tract 1 (TST 1) is attributed to the first stage of high-frequency volcanism (which started at ∼447.62 Ma) associated with the collision of the Cathaysia and Yangtze Blocks. The presence of the organic-fair lime mudstone/shelly limestone indicates that Hirnantian Glaciation in the highstand systems tract (HST). The occurrence of organic-rich siliceous shale interbedded with scarce bentonite layers in the transgressive systems tract 2 (TST 2) is attributable to the second stage of low-frequency volcanism (which started at ∼443.83 Ma) and to postglacial effects. The formation of organic-fair mixed shale with silty laminae is attributed to bottom-current activity in the early highstand systems tract (EHST). The occurrence of organic-poor clay-rich shale is due to terrigenous input in the late highstand systems tract (LHST). Our research also shows that the high marine productivity caused by volcanic ash and a high burial rate in an anoxic depositional setting led to organic matter and siliceous mineral enrichment in the TST 1 and TST 2. The favorable organic matter preservation conditions and the postglacial biotic recovery played significant roles in the formation of the organic-rich shale in the TST 2.

LanguageEnglish (US)
Pages74-85
Number of pages12
JournalMarine and Petroleum Geology
Volume102
DOIs
StatePublished - Apr 1 2019

Fingerprint

Analytical geochemistry
Glacial geology
Biogeochemistry
biogeochemistry
bentonite
Stratigraphy
Volcanoes
stratigraphy
systems tract
bottom current
Bentonite
calcium oxides
Shale
organic compounds
Organic compounds
Lime
volcanoes
Biological materials
Silurian
lime

Keywords

  • Bottom current
  • Genetic depositional model
  • Glaciation
  • Organic-rich shale
  • Terrigenous input
  • Volcanic activity

ASJC Scopus subject areas

  • Oceanography
  • Geophysics
  • Geology
  • Economic Geology
  • Stratigraphy

Cite this

Relationship between the origin of organic-rich shale and geological events of the Upper Ordovician-Lower Silurian in the Upper Yangtze area. / Wu, Lanyu; Lu, Yongchao; Jiang, Shu; Liu, Xiaofeng; Liu, Zhanhong; Lu, Yangbo.

In: Marine and Petroleum Geology, Vol. 102, 01.04.2019, p. 74-85.

Research output: Contribution to journalArticle

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