Stratigraphy of Devonian outcrop belts in northern Yukon Territory and northwestern District of Mackenzie (Operation Porcupine area)

Abstract

This revised account of the Devonian geology of the Operation Porcupine area is based primarily on 49 outcrop sections measured in 1962, 1970 and 1982, and incorporates new biostratigraphic data from numerous workers who have published on the area since 1968. The report area lies between latitude 65°N and the arctic coast and between longitudes 132°W and 141°W (Yukon-Alaska boundary) and embraces an area of 207 200 square kilometres. During Early and Middle Devonian time, carbonate successions were deposited on the Mackenzie Platform in the east, on the Yukon Stable Block in the west, and on two small isolated platforms, the White Mountains Platform in the north and Royal Mountain Platform in the south. During the same time interval, successions consisting largely of shale were deposited in the centrally located Richardson Trough and in the peripheral Blackstone, Selwyn, Hazen and Rapid troughs. The Lower and Middle Devonian successions on the Mackenzie Platform consist of the unnamed carbonate unit, together with the Cranswick, Hume, and Hare Indian formations. Slope deposits comprising a tongue of the Road River Formation and Mount Baird Formation (new name) are transitional between the Mackenzie Platform and Richardson Trough. On the Yukon Stable Block in the west, the carbonate succession consists of the Kutchin (new name) and Ogilvie formations and an unnamed shale unit. A succession showing a fluctuation between basinal shale and carbonate platform deposits comprises the Road River and Michelle formations in the Blackstone Trough, and the Ogilvie Formation and the unnamed shale unit on the Yukon Stable Block. Deep water sediments of the Road River Formation were deposited in the troughs. The uppermost Middle and Upper Devonian succession was characterized by a completely different sedimentary regime. Stratigraphic units comprise the Canol, Imperial, and Tuttle (new name introduced by Pugh, 1983) formations. The upper Middle Devonian Canol Formation is a dark euxinic shale that was deposited over a large part of the area and which is locally separated by an unconformity from underlying rock units. The succeeding Upper Devonian Imperial and Tuttle formations consist of fine to very coarse grained, elastic rocks. A small part of the Imperial Formation in the east is of shallow marine origin, but throughout most of the report area these two formations consist largely of flyschlike sediments and turbidites derived from an uplifted area in the north. The Tuttle Formation is uppermost and is dated by spores as latest Late Devonian and Early Carboniferous.

The pre-Mississippian "Neruokpuk Formation," northeastern Alaska and northwestern Yukon: review and new regional correlation

“…8) collected 1 Oldhamia from an undivided unit identified as being Middle Proterozoic to early Paleozoic in age. Oldhamia and other trace fossils have been recently reported from the British and Barn mountains in northern Yukon (A. W. Norris 1985;Lane and Cecile 1989;Lane et al 1991). Although a stratigraphic correlation with rocks of the Tindir Group cannot be confirmed at present, it is now apparent that at least some of the preMississippian strata of the northeastern Brooks Range is probably time-equivalent to some of the strata overlying the Tindir Group in east-central Alaska.…”

“…He chose to erect a completely independent classification, identifying seven informal units (PnO-Pn6, Fig. 3) totalling "in excess of 13 400 m" in thickness (D. K. Norris 1985~). Although D. K. Noms (1981aNoms ( , 1981b) disclaimed any stratigraphic order in his seven-unit classification, his later work clearly implies one (D. K. Noms 1985~).…”

“…However, a major regional reconnaissance effort, Operation Porcupine of the Geological Survey of Canada, led ty D. K. Norris, provided the first coherent geological framework for the region (Norris et al 1963), eventually mapping nearly 190 000 km2 at 1 :250 000 scale (e.g., D. K. Nonis 1981aNonis , 1981b. That project resulted in numerous comprehensive stratigraphic and biostratigraphic reports, several pertaining to the Paleozoic (e.g., Norford 1964; A. W. Norris 1968Norris , 1985. The only significant studies of Neruokpuk strata in the British Mountains were made during Operation Porcupine by D. K. Norris (1972Norris ( , 1976Norris ( , 1985aNorris ( , 1986) during regional reconnaissance mapping.…”

“…Although reconnaissance mapping is an important first step that focuses attention on those problem areas requiring more detailed work, understandably in this case, it has been insufficient to resolve the structural and stratigraphic complexities that exist in the pre-Mississippian succession of the northeastern Brooks Range. If there is a consensus, it is that structural complexity, facies changes, and lack of biostratigraphic control have made stratigraphic analysis particularly challenging (e.g., Dutro et al 1972;Sable 1977; D. K. Norris 1985~).…”

“…D. K. Norris (1985~) suggested an approximate correlation of his Neruokpuk units Neruokpuk in the Yukon. According to D. K. Norris (1985a), with the contiguous Alaskan units (Fig.…”