Paleosols: Sequence boundaries in continental rocks

Conference · Sat Jun 01 04:00:00 EDT 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5928171

Hanneman, D L ^[1]; Wideman, C J ^[2]

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1. Whitehall Geogroup, Inc., MT (United States)
2. Montana College of Mineral Science and Technology, Butte (United States)

Paleosols often mark unconformity surfaces on continental rock packages and thus may be used to delineate sequence boundaries. Paleosols are characterized by various diagnostic features such as calcic, argillic, and oxic horizons. Calcic-rich paleosols are of particular importance in seismic stratigraphy because of their morphology and mode of occurrence on and below major unconformity surfaces. Calcic layers are typically well indurated, range from 0.2 to 1 m in thickness, and contain thin zones of root mats. As determined by laboratory measurements of outcrop samples, densities of calcic paleosols range from 2.1 to 2.6 g/cm{sup 3} as opposed to densities of 1.4 to 1.7 g/cm{sup 3} for underlying, nonpedogenic rocks. The calcic paleosols are usually interbedded with nonpedogenic strata for up to 10 m below a major unconformity. Calcic paleosol zones can be projected from surface exposures into the subsurface for correlation with features on seismic reflection data. The use of paleosols as sequence boundary markers is analogous to the use of marine sequence markers and can provide a new and realistic basis for interpreting continental rock sequences.

• OSTI ID: 5928171
• Report Number(s): CONF-9107109--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 75:6
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
BOUNDARY CONDITIONS
BULK DENSITY
CHEMISTRY
COMPARATIVE EVALUATIONS
CORRELATIONS
DENSITY
EVALUATION
GEOLOGIC HISTORY
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOLOGY
GEOPHYSICAL SURVEYS
PHYSICAL PROPERTIES
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SEISMIC SURVEYS
SOIL CHEMISTRY
SOILS
STRATIGRAPHY
SURVEYS