Utility of San Juan basin silcretes

Conference · Fri Sep 01 00:00:00 EDT 1989 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:5631686

Gassaway, J S ^[1]

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1. Geological Survey, Denver, CO (USA)

Silcretes are silicified paleosols that formed as part of deep-weathering profiles during depositional hiatuses under humid climatic regimes. They provide chronostratigraphic support for hypotheses regarding local and regional tectonic and surface events. Silcrete occurs in the San Juan basin (SJB), near the top of the Kirtland Shale (Cretaceous), in the Ojo Alamo Sandstone (Paleocene), and in the Nacimiento Formation (Paleocene). These occurrences mark the southern limit of a 1,000 mi-long, discontinuous outcrop of silcrete discovered during reconnaissance of 16 Western Interior basins. These silcretes, common in Upper Cretaceous to middle Paleocene rocks, are rare in older and younger rocks. Recognition of silcrete occurrences may prove useful to field geologists where other chronostratigraphic information is absent. For example, geologists searching for the K-T boundary could use the lowest silcrete as a starting point.

• OSTI ID: 5631686
• Report Number(s): CONF-8910195-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 73:9; Conference: AAPG Rocky Mountain Section meeting, Albuquerque, NM (USA), 1-4 Oct 1989; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

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CENOZOIC ERA
FEDERAL REGION VIII
GEOLOGIC AGES
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020200* - Petroleum- Reserves
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