Influence of Pre-Mississippian Paleogeology on Carboniferous Lisburne Group, Arctic National Wildlife Refuge, Northeastern Alaska

K. F. Watts, R. Carlson, T. Imm, P. Gruzlovic, C. Hanks

The Carboniferous Lisburne Group of northern Alaska formed an extensive carbonate platform, which was later deformed as part of the Brooks Range fold and thrust belt. In the northeast, the Lisburne Group is parautochthonous and analogous to that at Prudhoe Bay. The Lisburne's paleogeography and facies relationships pertain to assessment of the petroleum potential of the Arctic National Wildlife Refuge (ANWR).

The Franklinian paleogeology, unconformably underlying the Ellesmerian sequence, has influenced sedimentation patterns in the Lisburne Group. The transgressive Endicott Group (Kekiktuk Conglomerate and Kayak Shale) and Lisburne Group thin northward over Franklinian basement highs. In the Sadlerochit Mountains, the Katakturuk Dolomite formed a paleotopographic high over which the Endicott Group pinched out and the Lisburne Group thinned. Shallow-marine oolitic grainstone developed in the cyclic Pennsylvanian Wahoo Limestone.

To the south in the Shublik Mountains, a repeated sequence of Katakturuk Dolomite and the Nanook Limestone were lower, so the Endicott Group lapped over the area and was later overlain by comparable Lisburne Group rocks. In the Fourth Range, the Lisburne Group is thicker and limestones also occur in the upper Endicott Group. Oolitic grainstone in the Wahoo Limestone is rare, and broad ooid shoals apparently pinched out into deeper water carbonates on a southward sloping carbonate ramp.

The belt of ooid shoals extended eastward across Leffingwell Ridge where the cyclic Pennsylvanian Wahoo Limestone is comparable to that of the Sadlerochit Mountains. The Kayak Shale includes a major interval of biostromal (reefal?) limestone. The Okpilak Granite formed another paleotopographic high directly overlain by the Lisburne Group.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.