Oct. 21, 2020,
noon - 1 p.m.
Justin Higa: Incipient breakup of the Isla Ángel de la Guarda microcontinent, Gulf of California, México Faults on microcontinents record the dynamic evolution of plate boundaries. However, most microcontinents are submarine and difficult to study. Here, we show that the southern part of the subaerial Isla Ángel de la Guarda (IAG) microcontinent is the likely site of an incipient plate boundary reorganization in the Gulf of California that may lead to future microcontinent breakup. To characterize the kinematics of this reorganization, we integrated remote fault mapping using high-resolution satellite- and drone-based topography with neotectonic field-mapping and 13 luminescence ages from sediment deposits offset or trapped by faults. Onshore, N-S striking normal faults occur along strike of a nascent offshore spreading center in the North Salsipuedes Basin, west of IAG. Late Pleistocene and Holocene luminescence ages indicate onshore fault activity in the last ~50 ka. These observations imply that the North Salsipuedes Basin is kinematically linked with active faults onshore IAG. Thus, crustal extension across southern IAG may connect to and reactivate extinct plate boundary structures east of IAG in the Upper Tiburón basin and play an important role in reorganizing the Pacific-North America plate boundary. ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////