Paleomagnetical Research On The Upper Cretaceous Jingzhushan Formation In The Lhasa Terrane

The formation and evolution of the Qinghai Tibet Plateau has long been the focus of attention at home and abroad. The collision between India and Eurasia plate led to the strong uplift of the plateau, eventually created the current tectonic pattern of Himalaya orogenic belt and the Tibetan plateau. The Lhasa block was located in the southern margin of the Asian continent before the collision, the unique geographical location plays an important role in the problem of initial collision time between the India and the Eurasian plate. As the India plate and Eurasia plate collision direction can be approximated to the north and south direction, so by studying the overlap of the two blocks of the ancient latitude can determine whether the collision occurred, after many years of research confirmed the paleo magnetism in rules of quantitative constraint plate evolution has unique advantages,The ancient latitude of plate for accurate description is a very important method of plate collision time.In this paper, we mainly study the system of the formation of sandstone samples from the upper Cretaceous strata of the Lhasa block. The sampling site is located in Bange Nagqu County,91 kilometers north, set a total of 10 sampling points, collected 114 pieces of paleomagnetic orientation. The following two results were obtained:?1? the rock magnetic experiments determine the formation of the main magnetic minerals are hematite, magnetite and. The system thermal demagnetization method magnetic cleaning for each sample, using Kirschvink principal component analysis method and Fisher average statistics for each sample analysis, most of the samples of the demagnetization curve reflects the characteristics of double component, which high temperature components resulted in the adoption of the strict inspection folds, may represent the primary remanence.10 mining point of the primary remanence direction through the average tilt correction for:D_s=328.4°,I_s=19.7°, K_s=30.9,?₉₅=8.8; Paleomagnetic pole position calculated is:?_p=53.1°,?_p=329.3°, d_p/d_m=9.2/4.8 ??_p is latitude,?_p is longitude?, conversion to the mining point ?32.8° N,90.0° E? the palaeolatitude of 10.1°.?2? the results with published Cretaceous paleomagnetic data indicate that the Lhasa block in the Cretaceous has been in a position of stable North 10°N?14°N.