Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy;Vol.XXII, No.2


A Paleomagnetic Reconnaissance of some late Precambrian to Early Paleozoic Rocks of Tansen Area, Lesser Himalaya, Nepal

Gautam, Pitambar

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For a preliminary paleomagnetic research on Late Precambrian to Early Paleozoic rocks in the Tansen area (West Central Nepal) carbonate, sandstone, quartzite and slate were collected from 30 sites at 4 localities. Detailed analyses of magnetic remanence were made using alternating field and thermal demagnetization techniques. Most of the specimens were found to be weakly magnetized (intensities of 10^-7 emu/cc, in order). Three magnetic components have been distinguished: (1) a predominant secondary component of recent origin, which represents a larger portion of the magnetization intensity in weakly magnetized specimens and thus hinders the separation of primary components. (2) another component (probably secondary), which yields a mean direction: D=320°, I=10°, a95=21° (before bedding correction) restricted only to purple slate varieties of Ramdighat Formation, and (3) a probably characteristic mean direction: D=350°, I=-45°, a95=15° derived from carbonate rock specimens of Kerabari Formation. This direction gives a virtual geomagnetic south pole position at 36°S/95°E.