Early Sevier orogenic deformation exerted principal control on changes in depositional environment recorded by the Cretaceous Newark Canyon Formation

Abstract

Terrestrial sedimentary archives record critical information about environment and climate of the past, as well as provide insights into the style, timing, and magnitude of structural deformation in a region. The Cretaceous Newark Canyon Formation, located in central Nevada, USA, was deposited in the hinterland of the Sevier fold–thrust belt during the North American Cordilleran orogeny. While previous research has focused on the coarser-grained, fluvial components of the Newark Canyon Formation, the carbonate and finer-grained facies of this formation remain comparatively understudied. A more complete understanding of the Newark Canyon Formation provides insights into Cretaceous syndeformational deposition in the Central Nevada thrust belt, serves as a useful case study for deconvolving the influence of tectonic and climatic forces on sedimentation in both the North American Cordillera and other contractional orogens, and will provide a critical foundation upon which to build future paleoclimate and paleoaltimetry studies. We combine facies descriptions, stratigraphic measurements, and optical and cathodoluminescence petrography to develop a comprehensive depositional model for the Newark Canyon Formation. We identify six distinct facies that show that the Newark Canyon Formation evolved through four stages of deposition: 1) an anastomosing river system with palustrine interchannel areas, 2) a braided river system, 3) a balance-filled, carbonate-bearing lacustrine system, and 4) a second braided river system. Although climate undoubtedly played a role, we suggest that the deposition and coeval deformation of the synorogenic Newark Canyon Formation was in direct response to the construction of east-vergent contractional structures proximal to the type section. Comparison to other contemporary terrestrial sedimentary basins deposited in a variety of tectonic settings provides helpful insights into the influences of regional tectonics, regional and global climate, catchment characteristics, underlying lithologies, and subcrop geology in the preserved sedimentary record.

How Hot Is Too Hot? Disentangling Mid‐Cretaceous Hothouse Paleoclimate From Diagenesis

“…Using the hotter vitrinite reflectance temperature for the Ely Limestone (144°C) and assuming the average geothermal gradient of ∼50°C/km for this region of the Sevier hinterland during the Cretaceous (e.g., Long & Soignard, 2016; Zuza et al., 2020), the Ely Limestone experienced an approximate burial depth of ∼3 km. If the peak temperature estimates reflect “burial 1” of the Carbon Ridge and Ely Limestone, then this implies that the maximum burial of the NCF is not much more than its thickness of ∼500 m (Di Fiori et al., 2020; Fetrow et al., 2020; Long, Henry, Muntean, Edmondo, & Cassel, 2014; Long, Henry, Muntean, Edmondo, & Thomas, 2014). There is very little indication that a thick sequence of younger sedimentary rocks was deposited on top of the NCF.…”

“…Thin sections ( n = 69) were made by Spectrum Petrographics, Inc. Samples from which δ 13 C, δ 18 O carb , and Δ 47 isotope analyses were measured were assessed for diagenetic changes using optical and cathodoluminescence petrography (see section below, and Fetrow et al., 2020). Carbonate mineralogy was determined by petrographic inspection, and, for a subset of samples, XRD analysis.…”

“…This suggests that the palustrine facies did not undergo significant secondary alteration due to hydrothermal fluids, in contrast to the lower lacustrine samples. On the other hand, evidence of mud cracking and pseudo-microkarstification found in the palustrine facies (Fetrow et al, 2020) indicate that evaporation was an active process in the palustrine environment, plausibly generating the spread in the palustrine isotope data (Figure 6).…”

“…Stage 2 does not preserve any carbonate‐bearing facies. Stage 3 was marked by a large‐scale, freshwater, balance‐filled lacustrine system that indicates either a reorganization of drainage patterns due to new structural containment or an increase in accommodation potentially due to subsidence in the piggyback basin while the sediment supply remained relatively constant (Fetrow et al., 2020). Lacustrine mudstones (calcareous mudstone facies, Fc (lake) ), biomicrites containing abundant fossil hash (biomicrite, Mb (lake) ), and non‐fossiliferous micrite (micrite facies, M (lake) ) are preserved in Stage 3.…”

“…Lacustrine mudstones (calcareous mudstone facies, Fc (lake) ), biomicrites containing abundant fossil hash (biomicrite, Mb (lake) ), and non‐fossiliferous micrite (micrite facies, M (lake) ) are preserved in Stage 3. After either a depositional hiatus or erosion representing ∼10 Myr, Stage 4 suggests a likely reinitiation of deformation in the region, represented by deposition of the final capping pebble to cobble conglomerate (Fetrow et al., 2020).…”