Clinoform geometries, facies distributions, and exploration significance of a Campanian spit, Billings, Montana

Conference · Sat Jun 01 00:00:00 EDT 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:6129456

Hanson, M S ^[1]

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1. Shell Western E and P, Inc., Houston, TX (United States)

A Campanian spit comprised of clinoform-bound sandstone wedges demarcates the base of the Eagle Sandstone along the rim-rocks surrounding Billings, Montana. The spit is connected to the Eagle strandline via a seismically defined northwest-southeast-trending basement fault which cores the Crooked Creek anticline. This recurrently active fault cut perpendicular to the Eagle strandline, localizing a fluviodeltaic headland which delivered an enormous volume of sand to the pendant spit. Detailed facies analysis of outcrop and subsurface data documents a strandline-parallel, southwesterly offlap of the sandstone wedges on the shallow shelf. Facies progressions within and across accretionary wedges define relative sea level movements during the genesis of the spit. Longshore and eddy currents, combined with a slow eustatic rise, forced a southwesterly migration of fine- to medium-grained sand. Spit progradation slowed and was ultimately terminated as the rate of eustatic rise overtook the rate of sediment supply. Spits resulting from similar/fault intersections are excellent exploration targets. The Billings spit spans 180 mi{sup 2} and reaches thickness exceeding 100 ft. A favorable reservoir/trap configuration results from the spit's lensoidal and potentially shale-encased geometry. Exploration for these spits must concentrate seaward and downcurrent of near-perpendicular fault/strand intersections.

• OSTI ID: 6129456
• Report Number(s): CONF-9107109-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 75:6; Conference: American Association of Petroleum Geologists (AAPG) Rocky Mountain Section meeting, Billings, MT (United States), 28-31 Jul 1991; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

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SANDSTONES
STRATIGRAPHY
DEVELOPED COUNTRIES
FEDERAL REGION VIII
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