Petrography of the Nanushuk Group and Torok Formation

Abstract

Modal grain size, percent visible porosity, effective porosity, and air permeability measurements of many of the sandstones of the Nanushuk Group and Torok Formation included in the petrographic study. 4. Tabulated modal compositions and textural data from petrographic examination of sandstones from the Nanushuk Group and Torok Formation.

Integrating stratigraphic modelling, inversion analysis, and shelf‐margin records to guide provenance analysis: An example from the Cretaceous Colville Basin, Arctic Alaska

“…The sediment discharge from the Brooks Range Orogenic Belt exhibits a decreasing trend from west to east. Hence, the model of the reconstruction of this clinothem in the Colville Basin indicates that the major influx of sediments was from the Chukchi Platform, Herald Arch, and western area of the Brooks Range Orogenic Belt, (areas A, B, and C respectively) which is consistent with previous provenance studies that employ petrographic analysis and detrital zircon U‐Pb ages (Figures 1 and 7) (Bartsch‐Winkler & Huffman, 1988; Lease et al., 2014; Moore et al., 2015; Mull, 1985; Wartes, 2008; Wartes & Reifenstuhl, 1998).…”

“…The application of the model methodology to this interval (120–97 Ma) of Colville Basin provenance is consistent with the interpretation of mixed sediment sources from previous sandstone point counting and detrital zircon studies. Quartz, chert, clastic sedimentary, carbonate, and metamorphic lithic grains are common in the sandstones of Nanushuk Formation (Bartsch‐Winkler & Huffman, 1988; Johnsson & Sokol, 2000; Moore et al., 2015; Wartes & Reifenstuhl, 1998). The sandstone composition suggests mixed source areas including recycled sedimentary or metasedimentary origin, as well as volcanic arc complex (Moore et al., 2015).…”

“…The spatial‐temporal evolution of the Nanushuk‐Torok shelf margins can be interpreted from seismic data (Houseknecht, 2019; Houseknecht et al., 2009; Molenaar, 1988; Schenk et al., 2012) and have been dated using U‐Pb geochronology (Houseknecht, 2019; Lease & Houseknecht, 2017) (Figure 1a). Previous provenance studies suggest that the sediments in the Cretaceous clastic infill were sourced from allochthons in the Brooks Range fold‐thrust belt, and a major highland centred in Chukotka (Russia) and the present‐day Chukchi Sea, where Paleozoic and Triassic‐aged clastics were uplifted and eroded (Bartsch‐Winkler & Huffman, 1988; Moore et al., 2015). Metamorphic detrital grains suggest deeper crustal levels are being exhumed and also contributing to the basin fill (e.g.…”