Characterizing Pre-Miocene Lower Plate Structures of the Northern Snake Range Metamorphic Core Complex, Eastern Nevada: Insights Into the Role of Tectonic Heredity in Metamorphic Core Complex Evolution

Late Cretaceous Crustal Shortening in the Northern Snake Range Metamorphic Core Complex: Constraints on the Structural Geometry and Magnitude of Pre‐Extensional Footwall Burial

“…U/Pb geochronology of zircon from three felsic dikes yield ages of 37.806 ± 0.026, 37.531 ± 0.009 Ma, and 37.504 ± 0.014 Ma (Lee et al., 2017; TIMMS). Preliminary U‐Pb LA‐ICPMS results from additional dikes range from 36 to 38.5 Ma (Wrobel, 2020) and broadly agree with the 37.5–37.8 Ma ages reported by Lee et al. (2017).…”

“…The unit's light color, paucity of mafic minerals, and ubiquitous presence of magmatic muscovite and garnet indicate Kpa intrusions are strongly peraluminous–part of a widespread suite of Cordilleran S‐type granites (Miller & Bradfish, 1980) interpreted to have been produced by crustal melting driven by Sevier‐Laramide crustal thickening in fluid‐rich crustal zones (Barbarin, 1996). Only a small fraction of Kpa bodies are dated, but an age of ∼84 Ma from Smith Creek (Huggins & Wright, 1989) and preliminary new ages ranging from 78 Ma to 82 Ma (Womer, 2017; Wrobel, 2020) suggest that virtually all of these Kpa bodies are part of the same Late Cretaceous magmatic event.…”

“…Strongly peraluminous leucogranites in eastern Nevada have also yield Late Cretaceous U‐Pb ages, ranging from 69 to 90 Ma (Lee & Christiansen, 1983; Miller et al., 1988), suggesting a protracted period of crustal melting associated with crustal thickening. New preliminary ages on different leucogranite bodies from various localities in the NSR yield reliable U‐Pb zircon ages from 75 to 85 Ma (Womer, 2017; Wrobel, 2020). The intimate association of these Late Cretaceous leucogranite bodies with metamorphic culminations in eastern Nevada and their interpreted petrogenesis from crustal melts (e.g., Miller & Bradfish, 1980) strongly support the notion that Late Cretaceous crustal thickening was largely responsible for both the metamorphism and S‐type magmatism of the hinterland region, and that there should be considerable overlap in the ages of all three processes.…”

“…This study presents new detailed mapping (Plate 1) and structural data that characterize footwall structures and stratigraphy where extensional overprinting is weakest. Mapping presented in plate 1 and Figure 4 is a compilation of 1:5000‐scale mapping by Womer (2017, MS thesis) and Wrobel (2020, this study) supplemented with existing 1:24,000 maps by Lee, Gans, et al. (1999a).…”