Neoproterozoic glaciation on a carbonate platform margin in Arctic Alaska and the origin of the North Slope subterrane

Abstract

The rotation model for the opening of the Canada Basin of the Arctic Ocean predicts stratigraphic links between the Alaskan North Slope and the Canadian Arctic islands. The Katakturuk Dolomite is a 2080-m-thick Neo protero zoic carbonate succession exposed in the northeastern Brooks Range of Arctic Alaska. These strata have previously been correlated with the pre-723 Ma Shaler Supergroup of the Amundson Basin. Herein we report new composite δ 13 C profi les and detrital zircon ages that test this connection. We go further and use stratigraphic markers and a compilation of δ 13 C chemostratigraphy from around the world, tied to U-Pb ages, to derive an age model for deposition of the Katakturuk Dolomite. In particular, we report the identifi cation of ca. 760 Ma detrital zircons in strata underlying the Katakturuk Dolomite. Moreover, a diamictite present at the base of the Katakturuk Dolomite is capped by a dark-colored limestone with peculiar roll-up structures. Chemostratigraphy and lithostratigraphy suggest this is an early-Cryogenian glacial diamictite-cap carbonate couplet and that deposition of the Katakturuk Dolomite spanned much of the late Neoproterozoic. Approximately 500 m above the diamictite, a micropeloidal dolomite, with idiosyncratic textures that are characteristic of basal Ediacaran cap carbonates, such as tubestone stromatolites, giant wave ripples, and decameters of pseudo morphosed former aragonite crystal fans, rests on a silicifi ed surface. Chemostratigraphic correlations also indicate a large increase in sedimentation rate in the upper ~1 km of the Katakturuk Dolomite and in the overlying lower Nanook Limestone. We suggest that the accompanying increase in accommodation space, along with the presence of two low-angle unconformities within these strata, are the product of late Ediacaran rifting along the southern margin of the North Slope subterrane. There are no strata present in the Amundson Basin that are potentially correlative with the late Neoproterozoic Katakturuk Dolomite, as the Cambrian Saline River Formation rests on the ca. 723 Ma Natkusiak Formation. Detrital zircon geochronology, chemostratigraphic correlations, and the style of sedimentation are inconsistent with both a Canadian Arctic origin of the North Slope subterrane and a simple rotation model for the origin of the Arctic Ocean. If the rotation model is to be retained, the exotic North Slope subterrane must have accreted to northwest Laurentia in the Early to Middle Devonian.

Biological Influences on Seafloor Carbonate Precipitation

“…B-D) Intensity maps of Mg, Fe, and Mn. The corresponding quantitative measurements for the different carbonate phases can be found in Table 4. Bushmansklippe Formation, Hayhook Formation, Mirasol d'Oeste Formation, Ol Member, Tsagaan Oloom Formation, Katakturuk Formation, Shareza Formation, and Kokarkuyu Formation) (Peryt et al, 1990;Saylor et al, 1998;James et al, 2001;Font et al, 2006;Hoffman et al, 2007;Macdonald et al, 2009aMacdonald et al, , 2009b. In some instances this interval also contains barite precipitates (e.g., Mackenzie Mountains), which suggests the condensation of substantial amounts of time onto this horizon (Hoffman and Schrag, 2002).…”

“…The Rainstorm Member crystal fans are not associated with the Marinoan cap carbonate sequence, which in the Death Valley Region is captured within the Noonday Formation (Corsetti and Kaufman, 2003;Corsetti and Grotzinger, 2005;Petterson et al, 2011). This occurrence is one of just a few examples of aragonite seafloor crystal fans in strata between the Marinoan-age cap carbonates and the seafloor fans of Lower Triassic strata, though crystal fans reported from the Katakturuk Dolomite in Alaska might be of similar age (Table 1) (Macdonald et al, 2009b). The Rainstorm fans coincide with the nadir of a major middle Ediacaran carbon isotope anomaly (211%o d 13 C VPDB ) termed the Shuram excursion (e.g., Kaufman et al, 2007;Pruss et al, 2008;Bergmann et al, 2011;Grotzinger et al, 2011;Verdel et al, 2011).…”

“…That in mind, the scarcity of carbonate platforms of middle Archean and early Paleoproterozoic age highlights the likelihood that both the 3.5 Ga to 3 Ga gap and 2.5 Ga and 2 Ga gap may be directly due to record bias. As summarized previously (Grotzinger, 1989;Grotzinger and James, 2000), subtidal crystal fans reminiscent of Archean and upper Paleoproterozoic seafloor crystal fans reappear in Neoproterozoic and Phanerozoic successions during periods of perturbation to the ocean-atmosphere system-most notably directly overlying the cap carbonate dolostones associated with the Marinoan glaciation (Hegenberger, 1993;Saylor et al, 1998;Clough and Goldhammer, 2000;James et al, 2001;Font et al, 2006;Hoffman et al, 2007;Macdonald et al, 2009aMacdonald et al, , 2009b and around the Permian-Triassic mass extinction (Grotzinger and Knoll, 1995;Pruss et al, 2006;Baud et al, 2007;Payne et al, 2007). The sedimentary record of the past 630 million years is, in many ways, much clearer and far more continuous, yet during this interval seafloor-precipitated fabrics are not ever a common component of carbonate platforms.…”

“…Doreen Formation, Australia (Kennedy, 1996), Bushmansklippe Formation, Namibia (Saylor et al, 1998), Hayhook Formation, Canada (James et al, 2001), Mirasol d'Oeste Formation, Brazil (Font et al, 2006), Ol Member, Tsagaan Oloom Formation (Macdonald et al, 2009a), Katakuruk Formation, Alaska (Clough and Goldhammer, 2000;Macdonald et al, 2009b) Crystal fans sit at the dolomite-limestone transition associated with the maximum flooding interval following the Marinoan Glaciation. They are often associated with pink limestones, authigenic minerals and microbial laminae.…”

Evidence for ca. 560Ma Ediacaran glaciation in the Kahar Formation, central Alborz Mountains, northern Iran

“…Subaqueous debris flow diamictites are generally moderate to thick with local or limited provenance (with source regions bearing on maturity), and display grading, clast imbrication, flow noses, plugs and pods of coarse debris, and internal shear planes (Stow, 2005;Eyles and Januszczak, 2004;Etienne et al, 2007;Boggs 2009;Macdonald et al, 2009;Arnaud and Etienne, 2011). We note that Kahar diamictites are thin, of mixed provenance, and structureless, with neither internal organization (e.g.…”