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Pt-group metal anomalies in the Lower Mississippian of southern Oklahoma

Charles J. Orth, Leonard R. Quintana, James S. Gilmore, James E. Barrick, Jill N. Haywa and Scott A. Spesshardt
Pt-group metal anomalies in the Lower Mississippian of southern Oklahoma
Geology (Boulder) (July 1988) 16 (7): 627-630


Four iridium (Pt-group elements) abundance anomalies have been found within a stratigraphic span of 3 m in the Lower Mississippian of Oklahoma. In ascending order, the first anomalies occur at the top of the Woodford Shale: Ir = 0.25 ppb, Pt = 48 ppb, Os = 7.5 ppb, and Au = 18 ppb. The anomalies occur just below a redox boundary and we suspect that the enriched elements were precipitated from sea water that contacted the organic- and sulfide-rick black shale. Two more anomalies occur in the Welden Limestone, the lower one weak and the upper one strong (Ir = 0.42 ppb, Pt = 50 ppb, Os = 0.075 ppb, and Au = 0.14 ppb). The excess Ir and Pt (also Co, As, and Ni) might have been enriched from sea water by bacteria at these two horizons. A 70-cm-thick interval of excess heavy siderophiles occurs in the overlying Caney Shale; the interval contains the following peak concentrations: Ir = 0.56 ppb, Pt =150 ppb, Os = 0.51 ppb, Co = 725 ppm, and Ni =1450 ppm. These elements vary in proportion to the Al (clay) content and we suspect that they were carried in with detrital material from erosion of ultramafic source rocks. We found no evidence of microspherules or shocked-mineral grains in any of these anomaly zones.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 16
Serial Issue: 7
Title: Pt-group metal anomalies in the Lower Mississippian of southern Oklahoma
Affiliation: Los Alamos Natl. Lab., Isot. and Nucl. Chem. Div., Los Alamos, NM, United States
Pages: 627-630
Published: 198807
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 16
Accession Number: 1988-048329
Categories: Geochemistry of rocks, soils, and sedimentsStratigraphySedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: sect.
N34°30'00" - N34°57'00", W96°55'60" - W96°22'60"
Secondary Affiliation: Tex. Tech Univ., USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 1988
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