- journal_title：Geology
- Contributor：Tonggang Zhang ; Wieslaw Trela ; Shao-Yong Jiang ; Jesper K. Nielsen ; Yanan Shen
- Publisher：Geological Society of America
- Date：2011-
- Format：text/html
- Language：en
- Identifier：10.1130/G32020.1
- journal_abbrev：Geology
- issn：0091-7613
- volume：39
- issue：7
- firstpage：675
- section：Articles
To understand probable influences of environmental changes on the decrease and rebound of biodiversity during the Late Ordovician, a detailed analysis of total organic carbon (TOC), pyrite, V/(V + Ni) ratios, and S isotopic compositions of pyrite in the Late Ordovician sediments from Poland was performed. The significant enrichments of TOC and pyrite as well as high V/(V + Ni) ratios (>0.6) for the Jeleniów Formation of the latest Darriwilian to middle Katian Stages provide evidence for predominant anoxic bottom-water conditions. In contrast, low TOC and pyrite as well as low V/(V + Ni) ratios for the Wólka Formation of late Katian age indicate oxic depositional conditions. The S isotopic data are consistent with the interpretations of oceanic redox conditions based on multiple proxies for paleoredox. The results from the Baltica area reveal a major oceanic redox condition change during the late Katian and suggest that oceanic oxygenation may have contributed to the rebound of marine animal diversity during the Late Ordovician.