Paleomagnetic study of the sediment from Amerasian Basin of the Arctic Ocean

The cores for paleomagnetic study were sampled during voyage of the Research Vessel "Academician Fedorov" in 2000. The region of investigation was eliminated by coordinates 81§° 54.90'-82O 05.22' N and 167O 52.32'-179O 56.17' E; sea depth in the 7 sites of the core sampling was between 1.5 and 3.3 km, total length of cores was 19.2 m. Magnetic susceptibility ¦Ê and natural remanent magnetization Jn were measured using a special set of equipment. Specimen selection along the cores was executed with minimal possible interval 2-2.5 cm. All in all 824 specimens were collected and measured. The measured magnetic susceptibility ¦Ê was varied in limits (2-6) 10-4 SI with average value 3.4 10-4 SI. Natural remanent magnetization Jn in cores was varied in limits (1.7-3.2) nT with average value Jn=2.5 nT. The position of ¦Ê and Jn extrema is coinciding in all cores, what creates the possibility for definition and correlation of sediment layers. Boundary Bruhnes-Matuyama (0.73 my BP) and subchron Jaramillo (1.07-0.99 my §£§²) were clearly fixed in all seven cores; subchron Olduvai (1.95-1.77 my §£§²) was marked in two cores, subchron Reunjon (2.13 my §£§²) ¨C in one core, boundary of subchron Matuyama-Gauss (2.6 my §£§²) was marked in three cores. The Bruhnes- Matuyama boundary was marked in all cores by especially big values of ¦Ê. Estimation sedimentation rate during Bruhnes epoch is, according to our measurement data, 1-1.4 mm/ky in five cores from Mendeleev Ridge, and 2.6-3.0 mm/ky ¨C in two cores from Podvodnikov Basin. This result coincides coinciding with published data relating to site of Mendeleev Ridge locating to north from 83° N. Evidences about low sedimentation rate in Amerasian Basin of the Arctic Ocean are the favorable precondition for search of ferromanganese nodules in this area. Work is carried out using support of RFFI (grant 06-05-64200)