This project is a comprehensive field and laboratory program that involves coordinated seismic, petrologic and theoretical modeling studies along an 800-km-long section of the Galapagos spreading center between 91 and 98 degrees west. The objectives of the project are to: (1) determine how the compensation of the Galapagos swell is partitioned between variations in crustal thickness and mangle density by measuring crustal thickness along the swell and the degree of melting inferred from the chemistry of basalts, (2) determine if there is a threshold factor that controls the transition from an axial high to a rift valley, (3) determine how the extent of magmatic differentiation of ridge basalts relates to the presence or absence of a melt lens, and (4) determine why the degree of partial melting appears to be lower near the hotspot.
