In northeastern Russia, reconnaissance analysis of the Anadyrsky and Khatyrsky sedimentary basins indicates that oil and gas fields were formed where strata of potential reservoir quality are present, and faults or zones of high permeability connect the source rocks to zones where impermeable strata overlie reservoir formations. Upper Cenozoic rocks, which have been subjected to Paleocene to Quaternary tectonic reactivation, the degree of which generally increases southward within individual basins, contain known oil and gas deposits in these basins. The formation of these basins is the result of extension and rifting along the northwestern edge of the Kamchatka Peninsula, specifically in the Penzhinskaya Guba region.