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Lakota Formation, southern Black Hills, South Dakota: an Early Cretaceous evolving fluvial system
Abstract
The fluvial, Early Cretaceous Lakota Formation consists of four spatially and temporally distinct sandstone units in the southern Black Hills and southeastern Powder River basin. Three of these units crop out in proximity to an area of uranium roll-front development (Edgemont mining district) where approximately 2300 wells were drilled and logged. Comparison of the resistivity logs of several of these wells with continuous cores of the Lakota Formation confirms their lithologic sensitivity. These logs (utilized to assist in subsurface facies interpretations where cores were not available), cores, and outcrops are the basis for the following facies interpretations. The discharge, sediment load, and resulting sinuosity of this fluvial system varied substantially throughout the time of Lakota deposition. The oldest unit consists of tabular deposits with complex internal architecture comprised of cross-cutting lateral accretion deposits. Upward-fining grain size, upward-decreasing scale of sedimentary structures, and the angular relationship between lateral accretion surfaces and overlying crevasse-splay deposits support this conclusion. The intermediate unit of ephemeral stream sediments is characterized by abundant pebble- and cobble-strewn erosional surfaces with up to 1.5 m relief, very poor clast sorting, and trough and planar cross-bedding with concave-upward foresets. The youngest unit has a predominance of tabular cross-bedding withmore »
- Authors:
- Publication Date:
- Research Org.:
- South Dakota School of Mines and Technology, Rapid City
- OSTI Identifier:
- 6963132
- Report Number(s):
- CONF-8609129-
Journal ID: CODEN: AAPGB
- Resource Type:
- Conference
- Journal Name:
- Am. Assoc. Pet. Geol., Bull.; (United States)
- Additional Journal Information:
- Journal Volume: 70:8; Conference: AAPG Rocky Mountain Section meeting, Casper, WY, USA, 7 Sep 1986
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 02 PETROLEUM; 11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; RESERVOIR ROCK; GEOLOGIC HISTORY; STRATIGRAPHY; SOUTH DAKOTA; CRETACEOUS PERIOD; GEOLOGIC FORMATIONS; LITHOLOGY; SEDIMENTARY BASINS; URANIUM DEPOSITS; FEDERAL REGION VIII; GEOLOGIC AGES; GEOLOGIC DEPOSITS; GEOLOGIC STRUCTURES; GEOLOGY; MESOZOIC ERA; MINERAL RESOURCES; NORTH AMERICA; RESOURCES; USA; 020200* - Petroleum- Reserves, Geology, & Exploration; 050100 - Nuclear Fuels- Reserves, Exploration, & Mining
Citation Formats
Dahlstrom, D J, and Fox, J E. Lakota Formation, southern Black Hills, South Dakota: an Early Cretaceous evolving fluvial system. United States: N. p., 1986.
Web.
Dahlstrom, D J, & Fox, J E. Lakota Formation, southern Black Hills, South Dakota: an Early Cretaceous evolving fluvial system. United States.
Dahlstrom, D J, and Fox, J E. 1986.
"Lakota Formation, southern Black Hills, South Dakota: an Early Cretaceous evolving fluvial system". United States.
@article{osti_6963132,
title = {Lakota Formation, southern Black Hills, South Dakota: an Early Cretaceous evolving fluvial system},
author = {Dahlstrom, D J and Fox, J E},
abstractNote = {The fluvial, Early Cretaceous Lakota Formation consists of four spatially and temporally distinct sandstone units in the southern Black Hills and southeastern Powder River basin. Three of these units crop out in proximity to an area of uranium roll-front development (Edgemont mining district) where approximately 2300 wells were drilled and logged. Comparison of the resistivity logs of several of these wells with continuous cores of the Lakota Formation confirms their lithologic sensitivity. These logs (utilized to assist in subsurface facies interpretations where cores were not available), cores, and outcrops are the basis for the following facies interpretations. The discharge, sediment load, and resulting sinuosity of this fluvial system varied substantially throughout the time of Lakota deposition. The oldest unit consists of tabular deposits with complex internal architecture comprised of cross-cutting lateral accretion deposits. Upward-fining grain size, upward-decreasing scale of sedimentary structures, and the angular relationship between lateral accretion surfaces and overlying crevasse-splay deposits support this conclusion. The intermediate unit of ephemeral stream sediments is characterized by abundant pebble- and cobble-strewn erosional surfaces with up to 1.5 m relief, very poor clast sorting, and trough and planar cross-bedding with concave-upward foresets. The youngest unit has a predominance of tabular cross-bedding with back flow climbing ripples and low dispersion of paleocurrent directions, suggesting a relatively straight, bed-load-type channel dominated by trains of sand waves.},
doi = {},
url = {https://www.osti.gov/biblio/6963132},
journal = {Am. Assoc. Pet. Geol., Bull.; (United States)},
number = ,
volume = 70:8,
place = {United States},
year = {Fri Aug 01 00:00:00 EDT 1986},
month = {Fri Aug 01 00:00:00 EDT 1986}
}