Lower Cretaceous fluvial-deltaic sediments at Kuk, Nugssuaq, West Greenland

Abstract

About 140 m of Lower Cretaceous sediments of the Kome Formation overly the gneiss basement in the Kuk, area. Three facies associations have been recognised in these sediments. Facies association A, which dominates the succession, consists essentially of trough cross-bedded coarse subarkosic sandstone alter­nating with dark laminated mudstone rich in coalified plant debris. Sedimentary structures, facies sequ-ences, and channel morphology suggest that this facies association was deposited by distributaries flowing from east-southeast across a delta plain. Facies association B occurs as coarsening-upwards mudstone - rippled fine sandstone - medium-grained sandstone sequences within the fluviatile sediments of facies association A. These sequences are regarded as the deposits of minor mouth bars and crevasse splays that prograded into interdistributary bays. Facies association C, consisting of tabular cross-bedded medium-grained sandstone, is interpreted as having been deposited from transverse bars in the distal part of a sandy braided river that flowed from south-southwest. The sub-Cretaceous sudace was a deeply weathered uneven plain; the present slopes and abrupt steps in this surface are entirely the result of post-Lower Cretaceous faulting and tilting. The sediments are cut off to the east by a major fault.