Date of Award
Master of Science (MS)
The first-order geologic and morphologic relationships at, along and proximal to ridge-transform-ridge plate boundaries are used to construct an empirical and speculative tectonic model. The geometry of a ridge-transform intersection necessitates the juxtaposition of relatively cold, thick lithosphere against the truncated end of an accreting plate boundary. The cold face of lithosphere cools the adjacent wedge of asthenosphere rising beneath the axis of accretion and restricts the amount of partial melting thus attenuating the amount of basaltic melt segregated from the asthenosphere per unit time. The manifestation of this cold edge effect is a thinner oceanic crust. At depth, upper mantle material is welded against the cold edge and creates a shear-couple that results in the progressive reorientation of tensile stresses as the ridge-transform intersection is approached. The model predicts that the geologic expressions of this cold edge effect will become more dramatic with increasing thickness of the truncating edge. Field data supporting this model were collected from the intersection of the East Pacific Rise with the Tamayo Transform Fault. The field program involved both a surface ship (R/V GILLISS) and a manned submersible (DSRV ALVIN).
Gallo, David G., "The influence of Oceanic Transform Boundaries on the generation and evolution of Oceanic Lithosphere" (1984). Geology Theses and Dissertations. 25.