PALEOMAGNETIC CAVE STRATIGRAPHY OF SEDIMENTS FROM HELLEMOFJORD, NORTHERN NORWAY

Subglacial deposited sediments from three deep karst caves in Nordland , northern Norway, carry single-component palaeomagnetic directions in terpreted to represent discrete records of palaeosecular variations (P SV) defining a clockwise rotation of the vector with time. The results suggest that preserved sediment sections commenced accumulating at th e highest altitude in this cave system, consistent with an inverse str atigraphic sedimentation. Anomalously low inclinations are interpreted to represent a detrital remanent magnetization acquired at the time o f deposition and affected by inclination error. The preservation of th e inclination error in these sterile sediments is attributed to the ab sence of processes that may cause post-depositional alignment of magne tic grains. Non-systematic directional scatter is also attributed to p oor smoothing of geomagnetic field variations in these cave sediments compared with lacustrine deposits. The almost closed PSV loop may repr esent discrete periods of sedimentation during one or, alternatively, several subglacial events. The PSV loop exhibits amplitudes in declina tion and inclination comparable with Holocene or Weichselian lacustrin e PSV records. The minimum duration of sediment accumulation may be of the order of 400 to 1000 yr. If the investigated sediments represent succeeding records of geomagnetic secular variations during the last L ate Weichselian glacial retreat, the reasonably good correlation with the PSV records from the Torreberga (Southern Sweden) varved clay sequ ence (12 200-10 200 BP) and UK lacustrine sediments (0-10 000 BP) tent atively suggests that the Ragge Javre Raigi sediments accumulated duri ng the final Weichselian glacial retreat between 10 900 and 9 800 BP.