| Most of the 282 peleomagnetic samples picked at Coqen and Xainza area in Gangdise plate are limestone(70%-80%). Via IRM obtained curve experiment, K-T curve and triaxial saturated isothermal remanent magnetic experiment, the paper differentiated the magnetic minerals of the typical samples and found that main dominated magnetic minerals are magnetite, iserite, maghaemite and a few of hematite.On the process of systematically thermal demagnetization, most of specimens appeared obvious two-component characteristic: when heated to 300℃-400℃, almost all samples were separated LTC which is very close to modern geomagnetic direction on geographic coordination and doesn't past the fold test. In this case , we can cognize it is remagnetization of modern magnetic field. High temperature component can be gained at 520℃-610℃,if the high temperature component of the Permian samples of two places are statistic together, positive and reverse polarity components are relative toes distribution, and pass the reversal test at 95% confidence level, so it can represent primary remanent magnetization of the rock formed period. The corresponding paleomagnetic pole position is: 224.4°E 33.3°N, paleolatitude is 15.4S; The paper stated the high temperature component of Carboniferous and Devonian sample, the result passed 99% and 95% fold test which indicated that steady high temperature was gained before stratum was folded, this component can represent primary remanent magnetization of the rock formed period. Paleomagnetic pole position in Carboniferous is 308.2°E 21.9°N, paleolatitude is 25.5S; m Devonian paleomagnetic pole position is 230.9°E 26.2°N, paleolatitude is 22.3S.It can be indicated form the paleolatitude data of each period that Gangdise block located at mid low latitude region of southern hemisphere from Early Devonian to Late Permian. The latitude changed 6.9°from Devonian to Permian which showed that in this period Gangdise block northward moved about 690Km, average speed was about 4.1 cm/a.
|
PDF Full Text Request