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Title: Geochemical evidence for a catastrophic biotic event at the Frasnian/Famennian boundary in south China

Abstract

A strong {delta}{sup 13}C anomaly coincides with a weak Ir anomaly at the Frasnian/Famennian (F/F) boundary exposed at Xiangtian, Guangxi, south China. The maximum whole-rock Ir abundance is 0.23 ppb (0.35 ppb on a carbonate-free basis) compared with averages of 0.016 and 0.044 ppb above and below the boundary interval. The {delta}{sup 13}C in carbonate abruptly shifts from a late Frasnian level of about +1{per thousand} to {minus}2.49 {per thousand}in the boundary interval and then abruptly returns to pre-boundary levels, suggesting a temporary reduction of surface-water biomass. A widely distributed (over at least several hundred kilometers) limestone breccia unit of possible wave-deposit origin is present directly below the boundary in south China. Enrichments of Al, V, Cr, As, and U, and a dip in the Mn abundance in the boundary interval indicate that reducing conditions might have been associated with the element enrichment. However, an alternative hypothesis is that oceanic impact(s) at the F/F boundary near south China provided the excess Ir and caused the biotic crisis and the formation of breccia deposits observed in the Late Devonian South China Sea.

Authors:
;  [1]; ;  [2];  [3];  [4]
  1. Univ. of Alberta, Edmonton (Canada)
  2. Los Alamos National Lab., NM (United States)
  3. Chinese Academy of Geological Sciences, Beijing (China)
  4. Geological Survey of Canada, Alberta (United States)
Publication Date:
OSTI Identifier:
5996303
Resource Type:
Journal Article
Journal Name:
Geology; (United States)
Additional Journal Information:
Journal Volume: 19:8; Journal ID: ISSN 0091-7613
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; CHINA; GEOLOGIC FORMATIONS; GEOCHEMISTRY; GEOLOGIC HISTORY; ALUMINIUM; ARSENIC; BOUNDARY CONDITIONS; CARBON 13; CARBONATE ROCKS; CHINA SEA; CHROMIUM; DEVONIAN PERIOD; DISASTERS; ECOLOGICAL CONCENTRATION; GEOLOGIC MODELS; IRIDIUM; ISOTOPE RATIO; LIMESTONE; MANGANESE; URANIUM; VANADIUM; ACTINIDES; ASIA; CARBON ISOTOPES; CHEMISTRY; ELEMENTS; EVEN-ODD NUCLEI; GEOLOGIC AGES; ISOTOPES; LIGHT NUCLEI; METALS; NUCLEI; PACIFIC OCEAN; PALEOZOIC ERA; PLATINUM METALS; ROCKS; SEAS; SEDIMENTARY ROCKS; SEMIMETALS; STABLE ISOTOPES; SURFACE WATERS; TRANSITION ELEMENTS; 580000* - Geosciences

Citation Formats

Wang, Kun, Chatterton, B D.E., Orth, C J, Attrep, M Jr, Hou, Hongfei, and Geldsetzer, H H.J. Geochemical evidence for a catastrophic biotic event at the Frasnian/Famennian boundary in south China. United States: N. p., 1991. Web. doi:10.1130/0091-7613(1991)019<0776:GEFACB>2.3.CO;2.
Wang, Kun, Chatterton, B D.E., Orth, C J, Attrep, M Jr, Hou, Hongfei, & Geldsetzer, H H.J. Geochemical evidence for a catastrophic biotic event at the Frasnian/Famennian boundary in south China. United States. https://doi.org/10.1130/0091-7613(1991)019<0776:GEFACB>2.3.CO;2
Wang, Kun, Chatterton, B D.E., Orth, C J, Attrep, M Jr, Hou, Hongfei, and Geldsetzer, H H.J. 1991. "Geochemical evidence for a catastrophic biotic event at the Frasnian/Famennian boundary in south China". United States. https://doi.org/10.1130/0091-7613(1991)019<0776:GEFACB>2.3.CO;2.
@article{osti_5996303,
title = {Geochemical evidence for a catastrophic biotic event at the Frasnian/Famennian boundary in south China},
author = {Wang, Kun and Chatterton, B D.E. and Orth, C J and Attrep, M Jr and Hou, Hongfei and Geldsetzer, H H.J.},
abstractNote = {A strong {delta}{sup 13}C anomaly coincides with a weak Ir anomaly at the Frasnian/Famennian (F/F) boundary exposed at Xiangtian, Guangxi, south China. The maximum whole-rock Ir abundance is 0.23 ppb (0.35 ppb on a carbonate-free basis) compared with averages of 0.016 and 0.044 ppb above and below the boundary interval. The {delta}{sup 13}C in carbonate abruptly shifts from a late Frasnian level of about +1{per thousand} to {minus}2.49 {per thousand}in the boundary interval and then abruptly returns to pre-boundary levels, suggesting a temporary reduction of surface-water biomass. A widely distributed (over at least several hundred kilometers) limestone breccia unit of possible wave-deposit origin is present directly below the boundary in south China. Enrichments of Al, V, Cr, As, and U, and a dip in the Mn abundance in the boundary interval indicate that reducing conditions might have been associated with the element enrichment. However, an alternative hypothesis is that oceanic impact(s) at the F/F boundary near south China provided the excess Ir and caused the biotic crisis and the formation of breccia deposits observed in the Late Devonian South China Sea.},
doi = {10.1130/0091-7613(1991)019<0776:GEFACB>2.3.CO;2},
url = {https://www.osti.gov/biblio/5996303}, journal = {Geology; (United States)},
issn = {0091-7613},
number = ,
volume = 19:8,
place = {United States},
year = {Thu Aug 01 00:00:00 EDT 1991},
month = {Thu Aug 01 00:00:00 EDT 1991}
}