Roberta Rudnick is a geologist who investigates the composition and origin of continental crust. Much of the lower continental crust is inaccessible to direct sampling, so its composition must be inferred by combining geochemistry, petrology and seismology. Her 1995 synthesis with David M. Fountain linked laboratory measurements of elastic wave speeds in rocks to seismic refraction surveys, using granulites to constrain the composition of the deep continental crust.[ref]
Nature and composition of the continental crust: A lower crustal perspective by Roberta L. Rudnick and David M. Fountain. Abstract and pp. 267–309: integration of seismic, petrological and geochemical constraints
Their reconstruction distinguished a compositionally heterogeneous, on average mafic lower continental crust from an intermediate-composition middle continental crust. The distinction matters for Earth's heat budget: the abundance of potassium, thorium and uranium, and hence heat production from radioactive decay, varies between rock types and with depth. Seismic wave speeds alone are not a unique chemical analysis; different rocks can have overlapping elastic properties, making independent constraints from geochemistry essential.[ref]
Nature and composition of the continental crust: A lower crustal perspective by Roberta L. Rudnick and David M. Fountain. Abstract: overlapping rock velocities, lower-crustal heterogeneity and heat-producing elements
Portrait of Roberta Rudnick
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