Microcontinent Breakup and Links to Possible Plate Boundary Reorganization in the Northern Gulf of California, México

Abstract

Microcontinents are fragments of continental lithosphere rifted away from a continent, now surrounded by oceanic lithosphere (Abera et al., 2016;Müller et al., 2001). Various mechanisms have been proposed for the isolation and tectonic evolution of microcontinents, each governed by a different tectonic setting (Nemčok et al., 2016). Continental fragments can become isolated by wrench faulting that forms strike-slip duplexes and stepovers between shear zones (e.g., Antobreh et al., 2009) or by horsetail splays via shearing of intervening blocks (e.g., Misra et al., 2014). Rifting across relatively parallel and overlapping spreading centers can also isolate microcontinents by two zones of extension and two sub-parallel transform boundaries (Nemčok et al., 2016) that can accommodate block rotation (Molnar et al., 2018). The role of a given microcontinent formation mechanism in the evolution of a plate boundary can be evaluated by constraining the orientation, sense of slip, and age of faulting on a microcontinent. However, most microcontinents are submarine (e.g., Nemčok et al., 2016), making them difficult to study.