Early Triassic stromatolites as post-mass extinction disaster forms

Journal Article · Thu Oct 01 00:00:00 EDT 1992 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1992)020<0883:ETSAPM>2.3.CO;2· OSTI ID:6937754

Schubert, J K; Bottjer, D J ^[1]

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1. Univ. of Southern California, Los Angeles (United States)

Aftermaths of mass extinctions have been thought to be characterized by relaxation of ecological constraints accompanied by increased prominence of opportunistic generalists. Such taxa, termed 'disaster forms,' have been shown to increase dramatically in range and abundance after several mass extinction events. The Cambrian-Ordovician stromatolite decline in normal-marine level-bottom environments has been explained as a direct or indirect consequence of increases in ecological constraints, such as greater levels of predation and/or bioturbation of microbial communities, caused by early Paleozoic benthic invertebrate evolution and diversification. Thus, one would predict that in post-Ordovician strata, stromatolites might appear in normal-marine level-bottom environments as disaster forms in the aftermaths of mass extinction particularly devastating to the benthic biota, such as during Early Triassic time. Mounded stromatolites are present in two beds (up to 1.5 m thick) of the Lower Triassic (Spathian) Virgin Limestone Member (Moenkopi Formation) in the southwestern Spring Mountains of Nevada. Stromatolites from level-bottom normal-marine subtidal environments have also been described from other Lower Triassic strata in North America, Europe, and Asia. These stromatolites, unusual in level-bottom normal-marine settings, may have developed locally during the long aftermath (4-5 m.y.) of the Permian-Triassic mass extinction because of partial relaxation of the ecological constraints that typically restricted them from unstressed subtidal, normal-marine, level-bottom environments.

• OSTI ID: 6937754
• Journal Information: Geology; (United States), Vol. 20:10; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CNIDARIA
BIOLOGICAL EXTINCTION
GEOLOGIC FORMATIONS
PALEONTOLOGY
GEOLOGIC HISTORY
LIMESTONE
NEVADA
TRIASSIC PERIOD
ANIMALS
CARBONATE ROCKS
COELENTERATA
DEVELOPED COUNTRIES
FEDERAL REGION IX
GEOLOGIC AGES
INVERTEBRATES
MESOZOIC ERA
NORTH AMERICA
ROCKS
SEDIMENTARY ROCKS
USA
580000* - Geosciences