Paleoenvironment of the Ogallala (Neogene) Formation in west-central Kansas

Conference · Mon Feb 01 00:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5932975

Twiss, P C; McCahon, T J; Oviatt, C G ^[1]

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1. Kansas State Univ., Manhattan, KS (United States). Geology Dept.

At Lake Scott (Scott County) in west-central Kansas, the Ogallala Formation unconformably overlies the Niobrara Formation (Cretaceous) and forms the bluffs of the north-trending Ladder Creek valley. Two sections (Devil's Backbone, 23 m thick; Suicide Bluff, 45 m thick) contain fluvial sands that grade upward into probable eolian sands. The lower sections contain poorly cemented, moderately sorted, arkosic sand, some mud gravel, and poorly defined fluvial channels. In the lower part of Devil's Backbone, cross-bedded sand is capped by mud drapes. At Suicide Bluff, beds of cross-bedded and better sorted sand occur high in the section. Paleosols and secondary calcite and opal dominate the sections. Pedogenic calcretes with more than 52% CaCO[sub 3] are especially abundant and range up to morphologic Stage VI. The [delta][sup 13]C and [delta][sup 18]O in the calcretes range from [minus]4.8 to [minus]6.5 and [minus]8.2 to [minus]6.7 per mil (PDB), respectively. Opal-A has replaced most rhizoliths of the Ogallala. Silicified fossil seeds (Celtis sp., Biorbia sp.) and probable fossil mammal burrows also occur in the sections. Rhyolitic tephra, about 10 Ma, occurs 12 m below the calcrete caprock of Suicide Bluff. A massive layer of opal occurs about 8 m above the tephra and below a diatomaceous bed. Siliceous cement occurs throughout each section, possibly originating from opal phytoliths, tephra, and/or diatoms. These sections afford the potential for understanding the stratigraphic succession and paleoclimate during the late Miocene to possibly early Pliocene in the central High Plains region.

• OSTI ID: 5932975
• Report Number(s): CONF-9303212-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 25:1; Conference: 27. annual Geological Society of America (GSA) South-Central Section meeting, Fort Worth, TX (United States), 15-16 Mar 1993; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
GEOLOGIC FORMATIONS
PETROLOGY
STRATIGRAPHY
KANSAS
ALLUVIAL DEPOSITS
CALCITE
CRETACEOUS PERIOD
DEPOSITION
GEOLOGIC HISTORY
LITHOLOGY
MINERALOGY
OPALS
PALEONTOLOGY
CARBONATE MINERALS
CHALCOGENIDES
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGY
MESOZOIC ERA
MINERALS
NORTH AMERICA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SILICA
SILICON COMPOUNDS
SILICON OXIDES
USA
580000* - Geosciences