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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 69 (1985)

Issue: 2. (February)

First Page: 291

Last Page: 291

Title: Recognition of Paleosilcretes: Example from North Texas: ABSTRACT

Author(s): Robert C. Murray

Article Type: Meeting abstract


Recognition of fossil silcretes may be hampered by weathering, erosion, or subsequent burial. Silcretes develop during periods of exposure and nondeposition and can represent cumulative sedimentation for geologically important periods of time.

The basal Cretaceous conglomerate in north Texas (Antlers and Twin Mountains formations) was deposited and lithified on the Wichita paleoplain. The silcrete formed in a tropical climate without seasonal variation. Outcrops are sporadic yet widespread and topographically prominant. The rock is a quartz and chert-pebble conglomerate with a variety of silica cements. It is recognized as a silcrete by the following criteria. (1) Both the detrital and authigenic components are composed primarily of silica. (2) Vadose quartz overgrowths are found in association with phreatic chalcedonic cements. Vadose silt occurs with both cement types. Zonation within the cements suggests intermittant cementation. (3) Reworked cemented grains indicate syndepositional cementation, necessarily a surface phe omenon. (4) Petrified wood is abundant. Abraded petrified wood further suggests recurring silicification and transportation.

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