Iridium abundance maxima at the latest Ordovician mass extinction horizon, Yangtze Basin, China: Terrestrial or extraterrestrial

Journal Article · Wed Jan 01 00:00:00 EST 1992 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1992)020<0039:IAMATL>2.3.CO;2· OSTI ID:7004069

Wang, Kun; Chatterton, B D.E. ^[1]; Attrep, M Jr; Orth, C J ^[2]

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1. Univ. of Alberta, Edmonton (Canada)
2. Los Alamos National Lab., NM (United States)

Neutron activation analyses of the Chinese Ordovician/Silurian (O/S) boundary sections at two distant localities in the Yangtze Basin, spanning the horizon of a major latest Ordovician global extinction event, show the maxima of iridium abundances to be coincident with the extinction horizon at the base of the graptolite Glyptograptus persculputs zone. The 0.23 ppb Ir maximum in the Yichang type section is almost as large as the late Eocene impact Ir anomaly. However, the authors have observed that the Ir abundances in the Chinese sections are closely correlated with the sedimentation rates, and therefore have concluded that Ir maxima do not indicate a cataclysmic extraterrestrial impact at this extinction level.

• OSTI ID: 7004069
• Journal Information: Geology; (United States), Vol. 20:1; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CHINA
SEDIMENTARY BASINS
GEOCHEMISTRY
PALEONTOLOGY
STRATIGRAPHY
BIOLOGICAL EXTINCTION
BOUNDARY LAYERS
CHEMICAL COMPOSITION
DEPOSITION
GEOLOGIC HISTORY
GEOLOGIC STRATA
IRIDIUM COMPOUNDS
NEUTRON ACTIVATION ANALYSIS
ORDOVICIAN PERIOD
SILURIAN PERIOD
YANGTZE RIVER
ACTIVATION ANALYSIS
ASIA
CHEMICAL ANALYSIS
CHEMISTRY
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GEOLOGY
LAYERS
PALEOZOIC ERA
REFRACTORY METAL COMPOUNDS
RIVERS
STREAMS
SURFACE WATERS
TRANSITION ELEMENT COMPOUNDS
580000* - Geosciences