Paleosols: Their use in well log correlation and seismic stratigraphy in Cenozoic basin-fill, southwestern Montana

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5691535

Hanneman, D L ^[1]; Wideman, C J ^[2]; Halvorson, J ^[3]

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1. Whitehall Geogroup, Inc., Whitehall, MT (United States)
2. Montana Coll. of Mineral Science and Technology, Butte, MT (United States). Dept. of Geophysical Engineering
3. Montana Board of Oil and Gas Conversation, Billings, MT (United States)

The use of paleosols as sequence boundary markers has recently been shown to be one of the most important tools for the interpretation of seismic data in regions of continental Cenozoic basin-fill material. Calcic paleosols and their defined sequence boundaries have been previously mapped on the surface and tied to seismic reflection data, and now can be delineated on well logs. Analyses of sonic and density logs from wells in the Deerlodge Valley, southwestern Montana, has resulted in the identification of several relatively thin, high velocity/high density zones which exist within the Cenozoic basin-fill. Zone thickness varies from 1 to 1.5 meters, and the zones are stacked up to as much as 40 meters. Density changes within the zones up to 0.6 g/cm[sup 3]. Velocity changes up to 1,660 meters/second. Well cutting chips from the high velocity/high density zones exhibit pedogenic features associated with calcic paleosols, such as clastic grains floating in micrite, grains corroded by calcite, and calcified root filaments. The authors generate synthetic seismograms from the sonic and density well logs which they analyze, and tie the seismograms to seismic reflection data using bright reflectors. The bright reflectors are interpreted as sequence boundaries on the seismic data and can be projected to the surface where they are associated with stacked zones of calcic paleosols which mark surface sequence boundaries.

• OSTI ID: 5691535
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
BOUNDARY CONDITIONS
CENOZOIC ERA
DATA ANALYSIS
DENSITY
DEVELOPED COUNTRIES
DIMENSIONS
GEOLOGIC AGES
GEOLOGIC HISTORY
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOLOGY
GEOPHYSICAL SURVEYS
MONTANA
NORTH AMERICA
PHYSICAL PROPERTIES
SEDIMENTARY BASINS
SEISMIC SURVEYS
SOILS
STRATIGRAPHY
SURVEYS
THICKNESS
USA
WELL LOGGING