Early middle Ordovician (Whiterockian) paleogeography of basin ranges

Conference · Fri Feb 01 04:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5141486

Ross, Jr, R J ^[1]; James, N P ^[2]; Hintze, L F ^[3]; Ketner, K B ^[4]

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1. Colorado School of Mines, Golden (United States)
2. Queens Univ., Kingston, Ontario (Canada)
3. Brigham Young Univ., Provo, UT (United States)
4. Geological Survey, Denver, CO (United States)

During a highstand of the Canadian shield over the Archean mantle root in the early Whiterock (Orthidiella zone), the western rimmed shelf evolved from a late Ibexian ramp. Calathid-sponge mounds initiated the rim on shelf, and micritic carbonate mounds formed on the upper slope. Large bodies of coeval upper slope mound lithology occur in northern nevada from Reed's Station on the west to The Narrows on the east; these Ordovician olistoliths (anomalously within Devonian deepwater facies) imply an early middle Ordovician carbonate escarpment from which huge blocks slid into deep water. Lowering of sea level at or after the close of the Ordovician may have resulted in displacement of such blocks. In the lower Anomalorthis zone, southwest of a line from Lytle Ranch to Cortex, shallow subtidal to oncolitic shoal water deposits form a vast prograding platform rim. To the northeast lay the partly euxinic, intrashelf Kanosh Basin. The boundary between the subsiding shale basin and the widening, upward shallowing oncolitic rim may have been a zone of hydrocarbon accumulation. Accelerated relative subsidence in the upper Anomalorthis zone resulted in transgression of the burrowed subtidal facies over the Kanosh basin. Southeastward over the site of the oncolitic rim, expansive tidal flat beds accreted repeatedly. Lastly, during Lichenaria-Opikina deposition, brief extensive transgression in the north was smothered by prograding quartz sand (Eureka Quartzite). The sands thinned and bypassed tectonically emergent islands along the Tooele arch. In the south, the sand appears to have poured into karst cavities in a belt from the Talc City Hills to the Sheep Range.

• OSTI ID: 5141486
• Report Number(s): CONF-9103128--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 75:2
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CARBONATE ROCKS
DEPOSITION
DEVELOPED COUNTRIES
FEDERAL REGION IX
GEOLOGIC AGES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
LEVELS
NEVADA
NORTH AMERICA
ORDOVICIAN PERIOD
PALEOZOIC ERA
ROCKS
SANDSTONES
SEA LEVEL
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
STRATIGRAPHY
USA