New In-Situ U–Pb Geochronology of Baddeleyite and Zircon from Mafic and Ultramafic Rocks at Matthews Ridge, NW Guyana

A regional suite of mafic and ultramafic rocks in the Matthews Ridge (MR) region of NW Guyana, Guiana Shield, South America, is the focus of geochronology and geochemistry studies to characterize the number of distinct magmatic suites, and for each, their ages, mantle sources and differentiation histories.