SEDIMENTATION IN A HIGH-LATITUDE KARST CAVE - SIRIJORDGROTTA, NORDLAND, NORWAY

Sirijordgrotta is 1100 m long with a vertical range of 90 m, and is a multistage, looping phreatic system. The cave is situated in the glaci ally sculptured valley Eiteradalen in Nordland, northern Norway. Four main environments of deposition during ice-covered periods have been r ecognized; clay deposited subglacially during full ice cover, coarse g ravel and allogenic boulders associated with high-energy emptying of w ater from the cave, predominantly sandy cut-and-fill facies associated with alternating high-energy water flow, and laminated fine sand and silts during almost stagnant conditions. The last three facies were pr obably deposited during deglaciation. A coarse gravel fill preserved i n a stream-cut canyon is recognized as the oldest post-dated sediment in Sirijordgrotta with a minimum age of 128 ka BP (U-series). This sed iment may represent a high-energy environment during the deglaciation of the Saalian ice sheet or an older deglaciation. Laminated clay depo sited during glacial damming of the cave contains ii paleomagnetic exc ursion which has been tentatively correlated to the Lake Mungo excursi on (28 ka BP). Based on paleomagnetism, we have correlated different s and and silt sections in the cave and proposed a regional correlation to British and Swedish (Torreberga) secular variation curves.