Subduction accretionary complex structural insights from the Tiburon Block of the Mesozoic Franciscan Complex, California, USA

Franciscan subduction accretionary complex rocks of the San Francisco Bay area, California, USA, constitute the basement rocks of several Cenozoic fault-bounded blocks of which the Tiburon Block is one. Strike-slip faulting has moved the blocks, including the Tiburon Block, by several to hundreds of kilometers, juxtaposing rocks from different parts of the accretionary complex. In addition, within the Tiburon Block syn- and post-accretion faulting—including out-of-sequence faulting and cross-strike faulting—and post-accretion folding deform the primary accretionary complex structure. Inter-fault sub-blocks of the Tiburon Block have different tectonostratigraphic characteristics and hence, different histories. The tectonostratigraphies, structures, and correlations of the sub-blocks together clarify the nature and deformational history of the Tiburon Block, allowing a generalized reconstruction of the primary accretionary architecture for this part of the Franciscan Complex. Recognition of cross-strike faulting and other post-accretion deformation is essential for reconstructing the geologic history of this and other parts of the Franciscan Complex and for reconstructing the structure and histories of other accretionary complexes worldwide in which post-accretion deformation affects accretionary complex architecture.