About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

Journal of Sedimentary Research (SEPM)


Journal of Sedimentary Research, Section B: Stratigraphy and Global Studies
Vol. 67 (1997)No. 6. (November), Pages 1001-1004

Walther's Law, Climate, and Upper Paleozoic Cyclostratigraphy in the Ancestral Rocky Mountains: CURRENT RIPPLES

Gerilyn S. Soreghan


Geologists routinely apply Walther's Law in interpreting paleoenvironments and paleogeographic scenarios from stratigraphic successions. The application of Walther's Law, however, may be problematic in strata that have been influenced by significant and geologically rapid climate change. Such climatic fluctuation can force depositional environments to change fundamentally rather than migrate laterally, resulting in a stratigraphic succession wherein depositional facies vertically superposed rarely or never coexisted laterally. Upper Pennsylvanian carbonate-siliciclastic cycles deposited in basins of the southern Ancestral Rocky Mountains display stratigraphic relations that cannot be explained by autogenic and/or glacioeustatic mechanisms alone; rather, intracyclic (glacial-interglaci l) climate change was a significant influence. Cycles of the northern Pedregosa basin, for example, comprise eolian-marine siltstone in sharp contact with subtidal-peritidal carbonate facies; absence of facies mixing suggests a climatic control on silt influx. Cycles of the western Orogrande basin comprise deltaic siliciclastic strata in sharp contact with subtidal-peritidal carbonate facies; absence of facies mixing, truncated siliciclastic progradation, and carbonate facies with emergence features similarly support a climatic influence on the siliciclastic component. In both systems, intracyclic (glacial-interglacial) climatic shift reconfigured depositional environments. In cases such as these, application of Walther's Law could produce erroneous conclusions. Severe glacial-interglaci l climate change helps explain the pervasive association of mixed carbonate-siliciclastic cyclicity that typifies upper Paleozoic strata in many parts of the world.

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Protected Document: $10
Internal PDF Document: $14
Open PDF Document: $24