Chapter 35 The Tatonduk inlier, Alaska–Yukon border

Abstract

Glaciogenic deposits of the Rapitan and Hay Creek Groups are exposed in the Tatonduk inlier of east-central Alaska and the western Yukon. The Rapitan Group ranges in thickness from c. 50 to 700 m with Fe-formation common in the upper 10 m. In the most distal settings, the Rapitan Group is separated from the diamictite of the Hay Creek Group by over 100 m of sandstone and siltstone; however, the Hay Creek Group contains large erosive surfaces and cannibalizing breccia, and rarely preserves strata between the two glaciogenic deposits. The diamictite of the Hay Creek Group is capped by a white-to buff-coloured dolostone with pseudo-teepee structures, bed-parallel, isopachous sheet-crack cements, and a depleted C-isotope signature. Late Neoproterozoic glacial deposits in the Tatonduk inlier were formerly assigned to the Tindir Group. To simplify the nomenclature in the northwestern Canadian Cordillera, the Tindir Group was abandoned and replaced with nomenclature consistent with that of the Windermere Supergroup in the Mackenzie Mountains. The mixed lithology and anchizone-grade metamorphism distinguish the Rapitan and Hay Creek Groups in the Tatonduk inlier as attractive future targets for integrated micropalaeontology, geochemistry, palaeomagnetism and geochronology.

Chapter 5 Chemical sediments associated with Neoproterozoic glaciation: iron formation, cap carbonate, barite and phosphorite

“…Haematite-jaspilite and ferruginous argillite occur within glaciogenic diamictite of the Rapitan Group and correlatives discontinuously for c. 800 km along the strike of the Ogilvie and Mackenzie mountains (Young 1976;Yeo 1981Yeo , 1986Eisbacher 1985;Klein & Beukes 1993;Macdonald & Cohen 2011). The glacial onset coincided with a major flood basalt episode across Arctic Laurentia, bimodal representatives of which underlie and intercalate the basal Rapitan diamictite in the Ogilvie Mountains, constraining its age at 717 Ma .…”

Evidence for early glaciation of southeastern Beringia

“…The Tatonduk site contains conglomeratic red beds 20-30 m thick that, by description, appear similar to those on Canadian and Tritop creeks (Cairnes 1914;Mertie 1930). Tatonduk red beds comprise Neoproterozoic (Cryogenian, 720-625 Ma) rocks deposited within a mid-Cretaceous to Paleogene foreland fold-and-thrust belt (Norris 1972;Allison et al 1981;Young 1982;MacDonald and Cohen 2011).…”

Supplemental Material: A detrital zircon test of large-scale terrane displacement along the Arctic margin of North America

“…Sample F845-82 is from the informal "upper shale" unit of the upper Fifteenmile Group in the Tatonduk inlier along the Alaska-Yukon border ( Fig. S1; Tables S1, S2; Macdonald et al, 2011;Macdonald and Cohen, 2011). This sample consists of coarse-grained quartz arenite collected from a m-scale channel within black and gray shale that is interbedded with lime mudstone and calcisiltite from just northwest of Mount Slipper.…”

“…Alaska-Yukon border region ( Fig. S1; Tables S1, S2; Macdonald et al, 2011;Macdonald and Cohen, 2011). This sample was collected from the same horizon as F845-82.…”