Sandstone wedges of the Cretaceous-Lower Tertiary Kangerlussuaq Basin, East Greenland – outcrop analogues to the offshore North Atlantic

Abstract

The Kangerlussuaq Basin is situated in southern East Greenland (68°30′N). The exposed 1 km thick sedimentary succession records a mid-Cretaceous to Tertiary basin history of Late Aptian–Albian transgression, Late Cretaceous–Early Paleocene highstand and mid-Paleocene uplift and erosion. The sediments are overlain by Upper Paleocene volcaniclastics, pyroclastics and flood basalts associated with continental break-up. Tertiary uplift and erosion has exposed the basin fill and it now represents one of the few outcrop analogues to the offshore Cretaceous-Tertiary sedimentary basins along the deep water margins of the North Atlantic. Three major sandstone-dominated intervals are identified in the succession: (1) mid-Cretaceous fluvio–estuarine sandstones; (2) Lower Paleocene submarine fan sandstones; and (3) mid-Paleocene fluvial and deltaic sandstones and conglomerates. The originally excellent reservoir properties of the sandstone bodies have been strongly modified by more than 4 km of burial and local high heat flux. Mechanical compaction, quartz precipitation, calcite cementation and illitization are the main porosity and permeability reducing agents in the rock sequence. The three major episodes of sandstone deposition were related to initial transgression and later relative sea-level falls and may help prediction of stratigraphic intervals with possible reservoir units in the undrilled offshore basins of the northern North Atlantic. The occurrence of mid-Paleocene proximal fluvial facies, thus suggests sediment bypass and deposition of coarse-grained clastics in the offshore areas southeast of Greenland and around the Faeroe Islands.