Caves and speleogenesis at Blomstrandsøya, Kongsfjord, W. Spitsbergen.

Abstract

Blomstrandsøya, at Kongsfjord (78 57’N), Spitsbergen, is within the high arctic, a completely permafrozen zone. The bedrock consistsof Paleozoic marbles and has yielded a surprising amount of karst features. Early phases of hydrothermal, possibly Caledonian,speleogenesis and subsequent Devonian karstification with redbed deposits is well documented. 62 active seacaves, and more than30 relict karst caves were found in the coastal cliffs and in escarpment faces around the island. All caves have very limited extent;they are either quite short, like most of the active sea caves, or they are soon choked by frozen sediments and ground ice after afew meters. The deepest penetration was some 34 m into the surface cliff. Many of the relict caves are scalloped and display welldefinedparagenetic wall and ceiling half-tubes, implying that they are indeed conduits, leading further into the rock mass, beyondtheir present permafrozen terminations. Most of the speleogenetic volume of the relict caves is ascribed to sub-glacial conditionsduring stadials, when the site was covered beneath thick ice sheets. In many cases, the present caves were formed by reactivationof pre-existing paleokarst voids. Due to the present intense gelifraction and erosion in the littoral zone, and the relatively constant sea level during the past 9.5 kyr, most of the volume of the sea caves can be explained by processes acting during the Holocene.

Keywords

• Karst
• speleogenesis
• arctic
• permafrost
• Quaternary
• subglacial