Abstract

Well-bedded and variably deformed Upper Cretaceous strata of the Cambria slab are in contact with highly deformed melange of the Franciscan Complex along the coast of central California. Past interpretations drew an analogy between these strata and small intraslope basins that highlight modern trench slopes. We have tested this hypothesis by integrating structural data with estimates of paleotemperature, using the technique of vitrinite reflectance. The maximum burial depth for Cambria deposits was about 6.5 km, and the paleogeothermal gradient was approximately 34 °C/km. The timing of peak heating remains uncertain, however. Maturation gradients and anomalies expressed at the surface are consistent with the slope-basin model, but the Cretaceous structural architecture has been modified considerably by Cenozoic folding and faulting.

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