Initiation, Evolution, and Destruction of an Early Paleozoic Carbonate Shelf, Eastern North Greenland

Abstract

In the early Cambrian of eastern North Greenland an initial peritidal carbonate platform developed following a transgression across a Precambrian craton. Subsequently, this was replaced by a terrigenous clastic shelf formed by shelf tilting, drowning offshore regions, and relatively uplifting shoreface areas so that clastics prograded shelfwards. In the late early Cambrian abrupt shelf drowning cut the supply of clastic material, and condensed phosphatic and glauconitic hardgrounds developed. Drowning may have been associated with initial shelf tilting, which proceeded to uplift the eastern shelf and caused substantial middle and late Cambrian erosion and produced a northwesterly prograding carbonate ramp wedge. A widespread early Ordovician transgression was followed by a large peritidal carbonate platform, which during the middle and late Ordovician evolved into a rimmed carbonate platform with occasional drowned interior. In the late Ordovician-early Silurian a peritidal carbonate platform developed, possibly by build-out from the rim and over the subtidal facies under the influence of a eustatic regression. Subsequently, the early Silurian shelf is comparable to a ramp as a composite series of sand shoals and drowned segments developed. Finally, the carbonate shelf was destroyed as it foundered into deep water, and terrigenous clastic turbidites covered it. Pinnacle reefs developed briefly at the beginning of subsidence.