Turkana Grits - a Cretaceous braided alluvial system in northern Kenya
Conference
·
· AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States)
OSTI ID:6221126
Rather spotty but excellent exposures of the Cretaceous-age Turkana Grits occur near the western shore of Lake Turkana, northern Kenya. These very coarse to pebbly arkosic sandstones and sandy conglomerates were derived from and rest unconformably upon Precambrian metamorphic basement; they are overlain by late Tertiary basaltic flows that comprise much of the volcanics in the East African Rift Zone. The formation ranges up to 2000 ft thick in the Laburr Range. Several outcrops contain sauropod, crocodile, and tortoise remains as well as abundant trunks of petrified wood (Dryoxylon). Five major facies make up the Turkana Grits and record a major episode of continental fluvial deposition in basins flanked by Precambrian basement. Facies 1 is crudely stratified, cobble and boulder conglomerate (clast-supported); Facies 2 is crudely stratified pebble-cobble conglomerate and pebbly sandstone; Facies 3 is trough cross-bedded, very coarse sandstones containing fossils wood and vertebrate remains; Facies 4 is crudely stratified to massive sandstones with ironstone nodules; and Facies 5 is red, purple, and gray mudstone and mud shale with carbonate nodules. Facies 1 through 3 record deposition in proximal to medial braided-stream channel, longitudinal bar and dune complexes. Facies 4 is a lowland, hydromorphic paleosol, and Facies 5 represents overbank and abandoned channel-fill sedimentation in an alluvial plain.
- Research Organization:
- Univ. of Arkansas, Fayetteville
- OSTI ID:
- 6221126
- Report Number(s):
- CONF-870606-
- Conference Information:
- Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Journal Volume: 71:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
AFRICA
ALLUVIAL DEPOSITS
CONGLOMERATES
CRETACEOUS PERIOD
DEVELOPING COUNTRIES
FOSSILS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
KENYA
MESOZOIC ERA
RIFT ZONES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SEDIMENTATION
020200* -- Petroleum-- Reserves
Geology
& Exploration
AFRICA
ALLUVIAL DEPOSITS
CONGLOMERATES
CRETACEOUS PERIOD
DEVELOPING COUNTRIES
FOSSILS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
KENYA
MESOZOIC ERA
RIFT ZONES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SEDIMENTATION