Meso-Cenozoic evolution of the southwestern Chukchi Borderland, Arctic Ocean

Cretaceous through Cenozoic strata that fill the North Chukchi Basin are part of the Brookian megasequence deposited across the foreland of the Chukotka and Brooks Range orogens. These strata form a series of clinothems deposited by northward-migrating depositional systems that progressively filled the North Chukchi Basin and buried the southern flank of the Borderland. Onlap of the Au by bottomset facies indicates that deep water conditions prevailed along the northern basin margin during Aptian-Oligocene. Foreset and topset facies onlap and overtop the highest standing part of the Borderland and indicate that marine slope and shallow marine to deltaic environments reached the Borderland during the Oligocene and persisted thereafter.