Abstract
Using updated ship-based geophysical data, along with seismic, geochronologic samples, and plate-motions allows us to evaluate crustal thicknesses and volumetric output of igneous material along the Galápagos hotspot track associated with the Galápagos mantle plume. This study compiles an extensive geophysical dataset, integrating 57 ship-based gravity surveys, six seismic tie locations, and updated bathymetry from GMRT v4.0 basemap across the Galápagos region to estimate crustal thickness of the area, which I sum above a baseline of 9 km ( 1 km), to calculate total igneous production of the plume. A total igneous volumetric production of 2.78x106 km3 from the Galápagos hotspot is summed along the Galápagos platform, Carnegie, Cocos, Malpelo, and Coiba Ridges assuming Airy-isostatic equilibrium. I also evaluate igneous production through time by estimating age of crustal material along pre-determined hotspot tracks on the Cocos and Nazca plates. My study constrains uncertainty due to sparse lava ages along the Carnegie and Cocos Ridges by using two methods for estimating when crustal material was emplaced. Using a sample-based method, I made age progression estimates using least squares fit of 175 radiometric ages to predetermined hotspot tracks along the Carnegie (n=127) and Cocos (n=48) Ridges. This provided a linear age-distance relationship to calculate age of volumetric contributions along track. The second method applies published plate motion rates to assign ages along the linear hotspot tracks. Together, these approaches allow for an evaluation of how total plume production has varied over time with plume-ridge proximity, including comparison between the two hotspot tracks. Overall, I find that intervals of increased igneous volumetric production from the hotspot are not limited to times of decreased plume-ridge separation, suggesting that periods of plume pulsation may exert a stronger control on volumetric production in the Galápagos than lithospheric thickness alone.