Drainage divide formation by uplift gradient onset: The case of the southern sector of the Main Gulf Escarpment, Baja California Peninsula, Mexico

Abstract

Field cases and numerical simulations support that uplift gradients set drainage divide close to the high uplift side. However, the development of a mountain landscape since the onset of one uplift gradient has been poorly documented. We analyze the case of the Main Gulf Escarpment (MGE) on the Baja California Peninsula (Western Mexico). The MGE is a landscape feature produced by El Carrizal Fault (ECF), an active normal fault that runs obliquely to the rifting system of the Gulf of California. By analyzing the rivers of the southern sector of the MGE with different approaches such as linear inversion, k_sn index, and drainage divide positions, we document how the different episodes along ECF tilted a volcanoclastic rock sequence known as Comondú Group, forming a main drainage divide that now corresponds to the MGE. The fault activity, which began in the Late–Miocene, was also advantageous in providing a reference time span to constrict the incision response of rivers to the episodes along ECF.