The geology of the Centrumsø area of Kronprins Christian Land, northeast Greenland, and lithological constraints on speleogenesis

The cave-bearing limestones of Kronprins Christian Land, northeast Greenland, were deposited on the Laurentian craton, on a sector of the margin referred to the Franklinian Basin. A 1.4km succession of Ordovician–Silurian carbonates rests unconformably on Lower Cambrian sandstones and Neoproterozoic sediments, and the carbonate succession is overlain conformably by late Llandovery (Silurian) turbidites that mark the collapse of the continental shelf at the onset of Caledonian tectonics, due to loading by thrust sheets and their erosional products. The cave-bearing limestones form a thin-skinned duplex that sits beneath the Vandredalen thrust sheet, which in turn lies in the footwall of a major fault that bounds exhumed, deep crustal rocks. Despite the thickness of the Lower Palaeozoic succession, most of the caves are concentrated in a thin interval comprising the subtidal–peritidal carbonates of the Odins Fjord Formation and the overlying reef limestones of the Samuelsen Høj Formation (both late Llandovery, Silurian). Caves are found only in the vicinity of the Samuelsen Høj reefs despite extensive exploration of the area as part of the regional mapping programme and the Greenland Caves Project, suggesting a possible genetic link even for those caves developed entirely within the Odins Fjord Formation.