A tectonic model for the Transcontinental Arch: Progressive migration of a Laurentian drainage divide during the Neoproterozoic–Cambrian Sauk Transgression

Abstract

A widespread provenance shift recorded by passive margin strata of western Laurentia, from predominant Stenian (1.2-1.0 Ga) detrital zircon age components to their absence, occurred during the Neoproterozoic-Cambrian Sauk transgression and is commonly used as a ca. 540 Ma chronostratigraphic marker throughout the west/ south-western United States. However, in Neoproterozoic-Cambrian strata of this region, we identify a probable shift from distal to more proximal Stenian-age zircon sources before a diachronous loss of Stenian detrital zircon age components. We suggest these provenance patterns reflect progressive subsidence of the passive margins surrounding Laurentia and concomitant relative uplift of the Transcontinental Arch, a broad and segmented northeast-southwest trending topographic high across the Laurentian midcontinent possibly due to lithospheric flexure. The Transcontinental Arch segments align with transverse rift structures of the Neoproterozoic-Cambrian Iapetan margin and the Mesoproterozoic Midcontinent Rift, perhaps reflecting rejuvenation of midcontinent lithospheric weaknesses during the Sauk transgression and final Rodinia breakup.

Supplemental Material: Neoproterozoic to early Paleozoic tectono-stratigraphic framework for central Idaho: Windermere Supergroup in the northern sector of the U.S. Cordillera

“…However, a similar provenance shift occurred after ca. 508 Ma in southeastern Laurentia (Karlstrom et al, 2018), and thus this provenance shift outside of southeastern Idaho and northern Utah appears to have been diachronous (Brennan et al, 2021c).…”

“…One possibility is that southern Laurentia underwent rift-flank uplift, which resulted in an influx of Stenian detritus into central Idaho. Furthermore, this suggests that uplift (or relative uplift) of the Transcontinental arch was progressive (from northeast to southwest) and primarily reflects subsidence of the Iapetan margin (Brennan et al, 2021c).…”

“…540-530 Ma chronostratigraphic marker in the region (e.g., Linde et al, 2014;Brennan et al, 2020b). However, redefinition of the age of Cambrian units in southeastern Laurentia (Karlstrom et al, 2018) and evaluation of additional isotopic constraints (Lu-Hf) on these Stenian grains (Howard et al, 2015;Brennan et al, 2021c) have prompted debate on the timing (Neoproterozoic?, Early Cambrian?, Late Cambrian? ), synchronicity, and mechanism of this provenance shift.…”

Macrostratigraphy of the Ediacaran System in North America

“…2,4A). Uncertainty has largely involved the timing of regional Rodinia rifting, whether there was one or two rift-to-drift transitions from the latest Neoproterozoic to the Middle Cambrian, and the timing of the development of a passive margin (Stewart, 1972;Christie-Blick and Levy, 1989;Ross, 1991;Dalrym-ple and Narbonne, 1996;Colpron et al, 2002;Ross and Arnott, 2007;Post and Long, 2008;Macdonald et al, 2012;Yonkee et al, 2014;Strauss et al, 2015;Moynihan et al, 2019;Brennan et al, 2020;Brennan et al, 2021).…”

Source‐to‐sink tandem geochronology reveals tectonic influences on the Cambrian Transcontinental Arch of Laurentia

“…Specifically, ca. 600–510 Ma siliciclastic rocks record an abrupt loss of Stenian (1.2–1.0 Ga) detrital zircon commonly attributed to disruption of a continental‐scale river system(s) that carried detritus from the Grenville orogeny and its correlates in the Appalachians and Texas, by epeirogenic uplift of the Transcontinental Arch (Figure 1; Brennan et al., 2021, and references therein). However, the timing, significance and very existence of the Transcontinental Arch are debated (Carlson, 1999; Hantsche et al., 2021; Myrow et al., 2003).…”