Tectonic control on the distribution on calcic paleosols in the Plio-Pleistocene Palomas half graben, southern Rio Grande Rift
- New Mexico State Univ., Las Cruces, NM (United States). Dept. Earth Sciences
- Ohio State Univ., Columbus, OH (United States). Dept. of Geological Sciences
The number and degree of development of calcic paleosols in the Palomas Formation, which was deposited during Pliocene to middle Pleistocene time in the Palomas half graben of south-central New Mexico, are related to position within the basin and asymmetrical subsidence. Numerous stage 2 morphology calcic paleosols, characterized by an argillic B horizon (Bt) overlying a horizon of distinct calcic nodules and tubules (Bk), developed on intermittently inactive parts of the broad (up to 20 km wide) bajada deposited on the hanging wall dip slope. During periods of movement of the basin-bounding fault, the gradient of the hanging wall dip slope increased resulting in channel incision and transportation of coarse detritus to the toe of the bajada. Stage 3 and 4 morphology calcic paleosols, which consist of Bt-K profiles up to 2 m thick, formed on terraces adjacent to the incised channels. In contrast, only a few stage 2 morphology calcic paleosols are present within footwall-derived alluvial-fan sediment, as the result of relatively rapid lateral shifting of depocenters on the small (less than 3 km[sup 2]) fans. However, some paleosols within footwall-derived by shallow phreatic cementation by coarse calcite. Rapid channel avulsion across the narrow (less than 5 km) axial-fluvial plain of the Ancestral Rio Grande inhibited development of paleosols except for a few rhizolith horizons. The spatial distribution of paleosols in the Palomas half graben may provide a predictive tool in interpreting ancient basin symmetry.
- OSTI ID:
- 5690341
- Report Number(s):
- CONF-921058-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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