W. W. Nassichuk

Cretaceous Cold-Seep Communities and Methane-Derived Carbonates in the Canadian Arctic

Lower Cretaceous cold-seep fossil assemblages have been found in the Canadian Arctic Archipelago. Serpulid worm tubes and bivalves are most abundant in these communities; in contrast, fossils are scarce in the surrounding strata. The fossils are contained in an isotopically light (δ13C = -25 to -50 per mil) carbonate rock groundmass that is interpreted to have formed from bacterial oxidation of methane. The rocks were deposited at intermediate depth (≤400 meters) in a cold marine environment; nearby normal faults may have provided a conduit for seeping methane and hydrogen sulfide needed to fuel chemosynthetic bacteria, and in turn, the higher life forms.

The Permian ammonoid Demarezites Ruzhencev from the Phosphoria Formation, Idaho

Representatives of the ancestral cyclolobin ammonoid Demarezites Ruzhencev (Cyclolobidae) are known from only a few localities in North America where they occur as rare faunal elements. Demarezites furnishi n. sp. is based on a single specimen from “Middle” Permian (Roadian) strata in the Meade Peak Member of the Phosphoria Formation in eastern Idaho. Several specimens of the closely comparable Demarezites n. sp., described herein, are known from the Pipeline Shale Member of the Brushy Canyon Formation in West Texas.

CISURALIAN AMMONOID GENUS URALOCERAS IN NORTH AMERICA

Abstract In North America, the ammonoid Uraloceras Ruzhentsev occurs in Cisuralian (Lower Permian) strata of the northern Yukon Territory, eastern Alaska, Ellesmere Island, southern British Columbia, and Nevada. From Sakmarian to Kungurian, species of Uraloceras occupied a narrow belt in the Northern Hemisphere (Boreal paleogeographical realm) that extended from the northern and northwestern margin of the Pangaean supercontinent southward to regions of present-day Siberia, the Ural Mountains, as well as Nei Monggol and Tibet. In the Yukon Territory, Nevada, Nei Monggol, and possibly Tibet, the association of Uraloceras with typically equatorial perrinitid ammonoids may represent a transition from “Boreal” occurrences in high latitudes to “Tethyan” of lower latitudes. Uraloceras nevadense n. sp. is described herein from Nevada and eastern Alaska.

Petroleum potential in Arctic North America and Greenland

Abstract Sedimentary deposition in Arctic North America and Greenland, in Phanerozoic time, occurred north of the Precambrian Canadian Shield and extended from the Wandel Sea in the east to the Chukchi Sea in the west. Seven geological provinces considered to be highly prospective for oil and gas exist within the region. Lower Paleozoic sediments may exceed 3000 m (10 000 ft) in the several separate basins in the Arctic Interior Platform of the Central Stable Region. To the north of the Arctic Interior Platform, lower Paleozoic sediments thicken into the Franklinian Geosyncline, the second geological province. Twelve thousand metres of lower and middle Paleozoic rocks are folded and faulted along a sinuous belt extending from the Wandel Sea in northeastern Greenland to Prince Patrick Island in the western Canadian Arctic Islands. Unconformably overlying the Franklinian Geosyncline are two successor basins, the third and fourth geological provinces considered in this report. The Sverdrup Basin in the Canadian Arctic Islands contains over 13 000 m (43 000 ft) of upper Paleozoic, Mesozoic and Tertiary sediments. The Wandel Sea Basin in and adjacent to northeastern Greenland, analogous to the Sverdrup Basin, contains a similar complement of upper Paleozoic, Mesozoic and Tertiary sediments. Onshore in Greenland, a composite thickness of 3000 m (10 000 ft) of sediments has been described and offshore, beneath the continental shelf, sediments in the basin may thicken to 10 000 m (33 000 ft). The Arctic Slope of Alaska, the fifth province, exhibits characteristics of a successor basin that has been rotated, translated or otherwise displaced from the Arctic Ocean Basin. Beneath a thickness of some 10 000 m (33 000 ft) of upper Paleozoic, Mesozoic and Tertiary strata is a folded and faulted lower and middle Paleozoic terrane similar to the Franklinian Geosyncline «Fold Belta. The southern margin of this province, now containing the Brooks Range, was folded and faulted during the Laramide Orogeny. A sixth province, the Arctic Coastal Plain, extends along the continents northern margin from Alaska, to northern Greenland. Strata ranging in age from Jurassic through Pleistocene thicken abruptly from a featheredge to more than 12 000 m (39 000 ft) as they prograde into the Arctic Ocean Basin. The seventh major geologic province is the Baffin Bay Basin, which contains some 10 000 m (33 000 ft) of Mesozoic and Tertiary sediments. With the exception of the Wandel Sea Basin, each of the geological provinces has had its petroleum potential evaluated from well-data. The Arctic Slope of Alaska has hydrocarbon reserves in the order of 1.6 × 109 m3 (10.0 Bbbl) of oil and 750 × 109 m3 (26.5 Tcf) of natural gas. Recoverable reserves for the Beaufort Sea-Mackenzie Delta region of the Arctic Coastal Plain are tentatively considered to be 0.15 × 109 m3 (943 MMbbl). The potential natural gas reserves for the Beaufort Sea-Mackenzie Delta region are in the range of 0.25 × 1012 m3 (8.83 Tcf). The Sverdrup Basin has yet to have significant reserves of oil indicated but the potential reserves of natural gas range from a minimum of 0.45 × 1012 m3 (15.89 Tcf) up to what will probably prove to be more than 565 × 109m3 (20 Tcf) with effective delineation drilling. The Franklinian Geosyncline contains both oil and gas but no significant reserves have been developed. The Wandel Sea Basin, Baffin Bay Basin and Arctic Stable Platform have yet to produce indications of significant pooled hydrocarbons. The undiscovered resource potentials of the Arctic Slope and contiguous Arctic Coastal Plain of Alaska have been estimated to have median values of 3.0 × 109 m3 (18.9 Bbbl) of oil and 1.39 × 1012m3 (49.08 Tcf) of natural gas. The undiscovered resource potentials of the Beaufort Sea-Mackenzie Delta region of the Arctic Coastal Plain have expected values of 1.35 × 109m3 (8.45 Bbbl) of oil and 2.91 × 1012m3 (102.75 Tcf) of natural gas. The combined resource potential of the Arctic Interior Platform, Franklinian Geosyncline, Sverdrup Basin and Baffin Bay Basin have expected values of 0.82 × 109 m3 (5.16 Bbbl) of oil and 2.98 × 1012 m3 (105 Tcf) of natural gas. The resource potential of the Arctic Islands Coastal Plain has not yet been effectively evaluated because the greater portion of the region lies beneath constantly shifting pack-ice and data required for a meaningful assessment are not available. It is possible however, that the Coastal Plain in the Arctic Islands area may have resource potentials as great as any other previously assessed Arctic province. Formal estimates of the resource potentials of northern Greenland and the Wandel Sea Basin are not available but on the basis of comparable geology, values can be expected to be proportional to those of the Arctic Interior Platform, the Franklinian Geosyncline and the Sverdrup Basin, respectively.