Distribution of rock types in the Mid-Cayman Rise, Caribbean Sea, as evidence for conjugate normal faulting in slowly spreading ridges

Abstract

The seemingly enigmatic exposure of predominantly plutonic rocks on the outer walls of the Mid-Cayman Rise can be explained by a structural model involving both inward-facing and outward-facing normal faults in the region of the median valley. Movement along inward-facing faults must dominate within the median valley to produce the topography observed; the less prominent scarps, which result from movement along outward-facing faults, are readily concealed by talus and pelagic sediment. Movement along these outward-facing faults increases as the crust passes through the transition between median-valley and rift-mountain topography.