Suggested revisions to the Tertiary tectonic history of north-central New Mexico

Abstract

Based on a variety of new or re-evaluated geo logica l and geophysical constraints , the following modifications to the Teniary tecton ic history of nonh-ccntral New Mexico are proposed: ( I) reverse faulting along the Pajarito fault zone defined the western boundary of a late Laramide base ment uplift (Pajarito uplift) that was contiguous with the Sangre de Cristo uplift to the east; (2) the Tijeras fault zone constitu ted a re leasing bend in the right-lateral strike-slip system of the Laramide southern Roc ky Mountains and controlled extensional subsidence within an Eocene half-graben to the nonhwest (the Gali,teo basin): (3) development of a flexural hi nge along a Laramide precursor to the Santa Ana accommodat ion zone (new name) may have faci litated the southeastward tilting of the floor of the Galisteo basin and locally delineated the sou thern boundary of the Pajarito uplift; and (4 ) the Pajari to uplift began to collapse due to extension beginning in the late Oligoceneearly Miocene, and continued subsidence and westward tilting of the resulting Espanola half-graben caused deposition of about 3 km of Santa Fe Group sediments near the Pajarito fault zone .