Exhumational History and Structural Geology

Angel Island is located in the San Francisco Bay and is separated from the Tiburon Peninsula to the north by Raccoon Strait. The dominant structure associated with the island and surrounding terranes is a broad north-west trending synform. Dip orientations, indicating such a structure on the island may be lacking, but are evident north and south of Angel Island. 

Using detrital zircon U-Pb age data, the structure,  provenance, and depositional history of the sandstone units can be constrained. Prominent age distribution peaks occur at 110Ma and 140Ma, these peaks coincide with times of voluminous plutonic activity in the northern Sierra Nevada. Maximum depositional ages range from ca. 85 Ma to 110 Ma; indicating deposition during the late Early Cretaceous and early Late Cretaceous.