Basin-fill architecture and forearc tectonics: Cretaceous Great Valley Group, Sacramento Basin, northern California

The Mesozoic Great Valley Group of the Sacramento Basin of northern California represents predominantly deep-marine sedimentation in a long-lived ponded forearc basin. Integrated subsurface and outcrop basin analysis reveals a complex, tectonically controlled basin-fill architecture.; Benthic foraminiferal biofacies indicate that Cretaceous deposition occurred entirely at bathyal and neritic depths, above the CCD ({dollar}<{dollar}3.5 km). The identification of depth-restricted genera allows the recognition of various neritic and bathyal depth zones. Results corroborate published paleobathymetric models, but with some modifications of potentially widespread applicability. The "flysch-type", low-diversity assemblage of simple agglutinated forms commonly associated with turbidite deposition is modified, including opportunistic calcareous genera.; Subsidence patterns and mechanisms were examined quantitatively by backstripping thirty-five stratigraphic sections. Accommodation of extremely thick Upper Mesozoic sediment accumulations along the basin's west side can be explained by simple sediment loading of underlying young, thermally-subsiding ophiolitic basement. Upper Cretaceous rocks comprise an eastward-tapering wedge lapping onto a relatively planar nonconformity. Pronounced, rapid, regionally-synchronous episodes of both subsidence and uplift, increasing in magnitude to the west, suggest flexural loading of an underlying rigid, buoyant crustal block. Hypothetical accretionary prism backthrusting over seaward portions of the forearc basin may explain the crustal loading. Regional subsidence patterns are complicated by localized intrabasinal folding and faulting.; Seismic and sequence stratigraphic interpretation of the Upper Cretaceous basin fill reveals a complex, tectonically controlled architecture. Two distinct types of sequence boundaries are identified: (1) beveling-type, exhibiting relatively planar erosion of the basin floor prior to widespread coarse-grained submarine fan deposition, and (2) entrenchment-type, showing deep incision of the basin floor by channels and canyons through which sediment bypassed the forearc basin. Onlap of topography draped by hemipelagic condensed sections defines a third bounding surface type, the draped onlap surface. All bounding surfaces reflect syndepositional basin tilting and deformation. Tectonic modification of basin floor relief and the accretionary prism sediment dam controlled sediment accumulation within the basin and forced episodic bypass of sediment to trench or trench-slope basins. Fluctuations in sediment supply to the forearc basin likely exerted an additional control.