The Cortez Mountains are located in north-central Nevada, southwest of Carlin (fig. 1). Previous geologic mapping in this region (Smith and Ketner, 1978) and previous stratigraphic studies (e.g., Smith and Ketner, 1976; Suydam, 1988) have defined an extensive exposure of the Early Cretaceous Newark Canyon Formation (NCF) on the eastern flank of the northern Cortez Mountains. In this region of Nevada, there have been differing interpretations of the timing and style of contractional deformation associated with construction of the Cordilleran mountain belt, as well as the potential relationship of the NCF to this deformation. Smith and Ketner (1977) did not observe evidence for contractional deformation in the NCF, and interpreted that regional Mesozoic contractional deformation must have taken place prior to NCF deposition.

Alternatively, Vandervoort (1987) and Suydam (1988) interpreted that the NCF was deposited in isolated basins that formed in response to regional tectonism along the ‘Eureka thrust belt’ (also known as the Central Nevada thrust belt of Taylor et al. [1993, 2000]). The goal of this study is to present map data that illustrate field relations between the NCF and surrounding rock units. We present a new 1:20,000-scale geologic map of the eastern flank of the northern Cortez Mountains that covers ~42 km² (a ~13 km north–south by ~4 km east–west distance), which covers the extent of exposure of the NCF (fig. 1). To illustrate the deformation geometry of the NCF relative to underlying and overlying rock units, we also present two retro-deformable cross sections. This report is meant to accompany Di Fiori et al. (2021), which characterizes the stratigraphic architecture, deposition timing, and deformation history of three NCF exposures in central Nevada, including the Cortez Mountains exposure. The following report provides descriptions of all rock and surficial units in the map area, with a focus on intraformational members of the NCF that we defined in our mapping, as well as the structural framework and geologic history of the map area and surrounding region.