Trace-element anomalies at the Mississippian/Pennsylvanian boundary in Oklahoma and Texas

Trace-element abundance anomalies have been found at the Mississippian/Pennsylvanian boundary. The boundary has been precisely located on the basis of an abrupt change in conodont diversity and species composition. Enriched elements include Os, Ir, Pt, Cr, most chalcophiles, REE and U. The anomalies...

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Bibliographic Details
Published in:Geology (Boulder) 1986-12, Vol.14 (12), p.986-990
Main Authors: Orth, Charles J, Quintana, Leonard R, Gilmore, James S, Grayson, Jr, Westergaard, Edwin H
Format: Article
Language:English
Subjects:
Ada region
anomalies
Barnett Shale
biostratigraphy
Canyon Creek
Carboniferous
Chesterian
Conodonta
enrichment
geochemistry
Lampasas County Texas
lithostratigraphy
Lower Pennsylvanian
Marble Falls Group
microfossils
Mississippian
Morrowan
Oklahoma
Paleozoic
Pennsylvanian
Pontotoc County Oklahoma
Rhoda Creek Formation
rock, sediment, soil
sections
sedimentary rocks
south-central Oklahoma
south-central Texas
stratigraphic boundary
stratigraphy
Texas
trace elements
United States
Upper Mississippian
Walker Ranch
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Summary:Trace-element abundance anomalies have been found at the Mississippian/Pennsylvanian boundary. The boundary has been precisely located on the basis of an abrupt change in conodont diversity and species composition. Enriched elements include Os, Ir, Pt, Cr, most chalcophiles, REE and U. The anomalies are more intense (e.g. Os 4 ppb, Ir 0.38 ppb, Pt 6 ppb, Cr 12 000 ppm, U 380 ppm) and persist through a thicker interval at the south-central Texas site than in Oklahoma. There are associated phosphate anomalies in both locations. Since there is no tangible evidence of an asteroid or comet impact source for the anomalies and faunal crisis, these phenomena may be related to a change in the Palaeozoic ocean chemistry, such as increased upwelling, stagnation, or nearby submarine volcanism.
ISSN:0091-7613
1943-2682
DOI:10.1130/0091-7613(1986)14<986:TAATMB>2.0.CO;2