The Coyote fan delta: a wave-dominated example from the Gulf of California Mexico

Abstract

Modern fan deltas from the Gulf of California are common along the high-relief cliffed peninsular margin. Most of the fan deltas are wave dominated, affected also by the longshore drift. Human impact on these fan deltas is minimal. Thus, El Coyote is an example useful for obtaining a better understanding of fan delta depositional systems in the stratigraphic record. Local rapid changes reflect the interaction of short-term summer flash floods and wave energy which rapidly removes the evidence of high discharges. The Baja California peninsula has been relatively stable, at least in the last few hundred thousand years, with an uplift rate of 100 mm/ka. Thus, changes in sea level and climate have been recorded on the fan delta as: (1) Pleistocene marine and fluvial terraces (possible stages 5e or 5c), (2) erosion of the subaerial portion due to lowering of sea level from a +1 to 1.5 high sea-level standard in the last 6000 years and a decrease in the rate of sediment discharge, and (3) the submerged fan form at a water depth of 40 m related to the high sea-level stands of stages 2 (28 ka) and 3 (40-45 ka).