Detrital zircon geochronology and provenance of the Middle Cambrian Flathead Sandstone, Park County, Wyoming

Abstract

We report the results of analyses of detrital zircon from the middle Cambrian Flathead Sandstone from four locations in Park County, WY. The Flathead U-Pb zircon age spectra (n=355) includes one peak at 2702–3345 Ma (95%) and two small age peaks at 1784 Ma (4%) and ∼1830 Ma (1%). Regional paleocurrent data for the Flat-head indicate sediment transport from east to west but the dominant Archean detrital zircons in our sample suite indicates a proximal source in structurally and topographically high Wyoming Province crust. The Archean ages are consistent with the >3.0 Ga fraction being derived from basement rocks present in the northern Beartooth Range and areas further to the west. The 2.8–3.0 Ga grains were derived from the Beartooth-Bighorn magmatic zone, which directly underlies and extends to the south and east of these Flathead sampling localities. The 1.7–1.8 Ga grains were derived from 100s of km to the south and east, in the Cheyenne Belt or more distal Yavapai Province rocks. This 1.7–1.8 Ga crust was uplifted along the Transcontinental Arch during late Precambrian time. The Transcontinental Arch, and perhaps the Midcontinent Rift further to the east as well, prevented easterly-sourced (i.e. Grenville) zircons from reaching the Wyoming Sauk shoreline.

Neoproterozoic Windermere Supergroup Near Bayhorse, Idaho: Late‐Stage Rodinian Rifting Was Deflected West Around the Belt Basin

“…Potential sources for the ca. 1,780 Ma grains include (1) the Yavapai province (including the Green Mountain arc of southwestern Wyoming; Jones et al, 2011; Reed et al, 1987) that was exhumed as part of the Transcontinental Arch (Malone et al, 2017), (2) the Swift Current anorogenic province of southwestern Saskatchewan and southeastern Alberta, Canada (Collerson et al, 1988; Linde et al, 2017; Matthews et al, 2018; Ross et al, 1991), and (3) a magmatic suite within the Great Falls tectonic zone (Mueller et al, 2002).…”

500–490 Ma detrital zircons in Upper Cambrian Worm Creek and correlative sandstones, Idaho, Montana, and Wyoming: Magmatism and tectonism within the passive margin

“…Middle Cambrian sandstone of the Flathead Sandstone overlies Archean Wyoming province basement (Middleton et al, 1980). Detrital zircons in the middle Flathead from the Bighorn Basin in northwest Wyoming and from southwest Montana contain a unimodal 1790 Ma peak (May et al, 2013;Mahoney et al, 2015), but this age peak is muted or missing in four samples of the Flathead from the southern Beartooth Mountains in northwest Wyoming (Malone et al, 2017). The bulk of the overlying Cambrian section is carbonate, but thin sandstone (that we sampled) is present at the top of the Upper Cambrian Du Noir Member of the Gallatin Formation, representing the Sauk II-Sauk III regression.…”

Orogenic Recycling of Detrital Zircons Characterizes Age Distributions of North American Cordilleran Strata

“…The LaHood Formation also contains abundant Archean DZ (Figure a) sourced from the Wyoming province. Following widespread Neoproterozoic cratonal denudation and the formation of the Great Unconformity, lowest Paleozoic marine sandstones were sourced from beveled North American basement terranes, as well as locally from underlying Mesoproterozoic sedimentary units, which, respectively, provided first‐ and poly‐cycle Cambrian and Mesoproterozoic‐Archean zircon to the lower Paleozoic section (Figure b; Baar, ; May et al, ; Link et al, , ; Malone et al, ). Modal provenance data support this interpretation, showing increased feldspar concentrations where the Cambrian Flathead Sandstone unconformably overlies quartzofeldspathic basement and Mesoproterozoic strata (Graham & Suttner, ; McLane, , ; McMannis, ).…”