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Abstract: Critical Stratigraphic, Structural, and Timing Relations within the Western Sierra Nevada, California, and Their Bearing on Models for Origin of the Foothills Terrane and the Great Valley Basin


Several models exist for Jurassic-Cretaceous evolution of the western Sierra Nevada, the adjacent Great Valley basin, and the Coast Range ophiolite, as recently clarified by Dickinson and others (1996). To evaluate the models requires both an examination of critical stratigraphic and structural relations within the western Sierra Nevada and the Coast Ranges (a data quality issue), and an understanding of predictions or requirements of the various models (e.g., can any model be falsified by reliable data?).

In some cases, reliable data may contradict a model, but not rule it out, and the model can be made more complex, such as invoking noncollisional, intraarc contractional deformation along a convergent margin. However, any model whose predictions can be falsified by, or whose requirements are incompatible with, reliable data probably should be eliminated.

Within the western Sierra Nevada metamorphic belt and in isolated pendants in the southwestern Sierra, controversy surrounds many of the units, largely because uncertainty exists about correlations and links between units, their probable tectonic significance and ages, and the timing and styles of deformational events and structural elements. This paper reviews and summarizes new and published stratigraphic, structural, and timing relations, to evaluate which are well established, and to highlight critical uncertainties and unknowns. Well-established relations are compared with predictions of various models, both to determine if any models are incompatible with or can be falsified by reliable data, and to suggest important future tests of the models.

Search and Discovery Article #90945©1997 AAPG Pacific Section Meeting, Bakersfield, California