ABSTRACT
The lateral transition from platform carbonates of the middle Llandovery (lower Silurian) Adams Bjerg Formation to slope deposits of the Cape Schuchert Formation is well exposed at Kap Jefferson, Washington Land, North Greenland. These platform and slope sediments conformably overlie upper Ordovician to lower Silurian platform carbonates of the Aleqatsiaq Fjord Formation. Two undolomitised shallow subtidal platform facies, one composed of nodular limestone and the other of interbedded calcarenite and black mudstone, characterise the underlying Aleqatsiaq Fjord Formation. Four dolomitised facies, crinoid, stomatolite, massive and skeletal sand have been identified in the overlying Adams Bjerg Formation. These facies represent a mosaic of shallow subtidal and intertidal platform environments. All but the massive facies interdigitate with upper-slope deposits of mudstone, lime mudstone, chert and calcarenite of the Cape Schuchert Formation. The facies of the Cape Schuchert Formation represent quiet proximal-slope deposition, periodically interrupted by higher-energy deposition of calcarenite and influxes of exotic blocks of platform carbonate.
Dolomitised buildup and platform-edge carbonates, as at Kap Jefferson, are known throughout the Canadian Arctic Islands, but not in other parts of North Greenland, suggesting a similarity between Silurian sedimentary patterns in Washington Land, North Greenland and Arctic Canada. Dolomitised platform and platform-edge carbonates in this region are associated with a continuous transition into mudstone deposits of the slope. Such transitions are ramp-like in character. Dolomitised carbonates, as at Kap Jefferson, are not associated with more abrupt fault-scarp margins between platform carbonates and trough turbidites.
