Origin of the Lisburne Hills–Herald Arch structural belt: Stratigraphic, structural, and fission-track evidence from the Cape Lisburne area, northwestern Alaska

Abstract

The Lisburne Hills fold and thrust belt forms the on-land segment of an 800-kmlong arcuate structural belt that also includes the offshore Herald and Wrangel Arches in the Chukchi Sea. The regional north-south trend of structures on the Lisburne Peninsula contrasts sharply with the east-west trend of structures in the Early Cretaceous Brooks Range orogen to the southeast. In the northern Lisburne Hills, our new mapping documents three northeast-plunging, northeast-vergent structural domains: (1) imbricated Lisburne Group carbonate rocks, (2) complexly folded µne-grained strata of the Etivluk Group and Kingak Shale, and (3) isoclinally folded Brookian sequence turbidites. A balanced cross section across the Lisburne domain indicates a minimum of ∼ ∼65% shortening, generally comparable to estimates for Neocomian shortening within the Brooks Range. Thermal maturity and µssion-track data indicate that all three domains experienced rapid thrust-induced burial and heating bracketed between 132 and 115 Ma, followed quickly by ∼ ∼5 km of erosional exhumation at ca. 115 Ma.We conclude from similarities in age, deformational style, and percent shortening that the Lisburne Hills represents a northward projection of the frontal zone of the Brooks Range orogen. Deformation appears to be too old for previous models that ascribed the Lisburne Hills to post-Brooks Range convergence between North America and Eurasia. The Lisburne Hills may have originated at a high angle to the Brooks Range proper along the eastern margin of a western salient of the Brooks Range that developed in response to westward thinning and onlap of the Ellesmerian sequence onto the Chukchi platform. 77

Fold belts and sedimentary basins of the Eurasian Arctic

“…Lower Paleozoic rocks in the NE Brooks Range and especially the North Slope subsurface include significant packages of deformed Early Devonian orogenic clastic rocks interpreted to be Caledonian-sourced. Two prominent structural unconformities, (1) Sub-Mississippian and (2) lower Cretaceous (sub-Aptian) document the occurrence of two major orogenic phases across the entire AACM [98][99][100][101].…”

“…On the Chukchi Peninsula and probably on Wrangel Island, this orogenic event was followed by uplift and profound erosion between c. 117 and 95 Ma [96]. On the Lisburne Peninsula, the early Brookian largely thin-skinned deformation ended at c. 120 Ma and was followed by extensional exhumation at c. 115-90 Ma [100].…”

Closing the Canada Basin: Detrital zircon geochronology relationships between the North Slope of Arctic Alaska and the Franklinian mobile belt of Arctic Canada

“…9 and 10). Exposed parts of the Chukchi Platform were likely sources for strata at Cape Lisburne and in the western Hanna Trough (Moore et al, 2002;Sherwood et al, 2002), while the low-lying landmass of Crockerland fed the outboard margin of the Sverdrup Basin (Embry, 2009) (Fig. 9).…”

New insights into Arctic paleogeography and tectonics from U‐Pb detrital zircon geochronology

“…[26] The Lisburne Hills fold-and-thrust belt in westernmost Alaska (Figure 3) consists of lower Paleozoic to Mesozoic sedimentary rocks involved in Brookian thrusting [Moore et al, 2002]. Two samples were collected from an unusual sandstone member of the Triassic Otuk Formation.…”