Stratigraphy and tectonic setting of the Lower Cretaceous King Lear Formation, Jackson Mountains, northwest Nevada
Martin, Aaron James
Wright, James E.
Master of Arts
The lower Cretaceous King Lear Formation (KLF) is a gently east-dipping succession of alluvial conglomerates and sandstones that were deposited in a small intra-arc basin. Supracrustal strata of Cretaceous age from within the western U.S. magmatic arc are extremely rare, so the KLF offers an opportunity to obtain paleoenvironmental information about the Cretaceous arc. A new division of the KLF into three members based on clast provenance provides a framework for understanding deposition in the King Lear Basin and thus is essential for paleoenvironmental studies on this portion of the arc. New structural observations and a shallow reflection seismic profile suggest that the KLF was deposited in a half-graben and never experienced compressive deformation. This conclusion means that compressive deformation both in the Jackson Mountains and also in the crustal-scale Luning-Fencemaker Fold and Thrust Belt must have been complete prior to the Early Cretaceous.