Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Latest Permian to Middle Triassic redox condition variations in ramp settings, south China; pyrite framboid evidence

Huang Yuangeng, Chen Zhongqiang, Paul B. Wignall and Zhao Laishi
Latest Permian to Middle Triassic redox condition variations in ramp settings, south China; pyrite framboid evidence
Geological Society of America Bulletin (October 2016) 129 (1-2): 229-243

Abstract

A detailed, 10 m.y. redox history of Changhsingian to Anisian (latest Permian to Middle Triassic) oceans in ramp settings is reconstructed based on framboidal pyrite analysis from South China. The result shows that the well-established phenomenon of intense ocean euxinia-anoxia is faithfully recorded in pyrite framboid data. Three major euxinia-anoxia episodes, namely, the end-Changhsingian to end-Smithian, middle to late Spathian, and early to middle Anisian, have been recognized from the ramp successions. The first reducing episode is subdivided into four subepisodes: Permian-Triassic boundary, Griesbachian-Dienerian boundary, earliest Smithian, and end-Smithian. Redox variations broadly track other oceanographic proxies. Euxinia-anoxia episodes coincide with positive excursions of conodont Omega Ce anomalies, negative excursions of delta (super 34) S (sub cas) (carbonate-associated sulfate), increases in sea-surface temperature, and negative excursions of delta (super 13) C in most cases. However, euxinia-anoxia near the Dienerian-Smithian boundary coincided with positive excursions of delta (super 13) C and a general cooling period. This exception may be the result of locally developed water-column anoxia. The Permian-Triassic boundary subepisode witnessed two ephemeral euxinia-anoxia events separated by a dysoxic to oxic period. The former, together with a rapid increase in sea-surface temperature (up to 8 degrees C), may have been responsible for the biodiversity crisis, while the latter anoxic event destroyed ecosystem trophic structures. In addition to the Permian-Triassic boundary euxinia-anoxia event, which spread over habitats in all oceans, the Spathian and Anisian euxinia-anoxia episodes also prevailed in global oceans. Variation of the oxygen minimum zone are suggested as the driving mechanism that facilitated the movement of oxygen-poor water columns in various paleogeographic settings over this critical period.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 129
Serial Issue: 1-2
Title: Latest Permian to Middle Triassic redox condition variations in ramp settings, south China; pyrite framboid evidence
Affiliation: China University of Geosciences, State Key Laboratory of Biogeology and Environmental Geology, Wuhan, China
Pages: 229-243
Published: 20161018
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 91
Accession Number: 2017-002993
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. col., geol. sketch map
N31°08'60" - N31°08'60", E119°54'00" - E119°54'00"
Secondary Affiliation: University of Leeds, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201703
Close Modal

or Create an Account

Close Modal
Close Modal