Movement History of the Microcontinents from the Tibetan Plateau Based on Paleomagnetic Results with Sufficient Sampling Units

Paleomagnetic results cannot be applied in global and regional tectonic reconstructions unless the paleosecular variation has been adequately averaged. However, how many sampling sites and samples are enough to calculate a reliable paleopole remains debated. Based on the relation among the sampling sites N, the precision parameter k, the virtual geomagnetic pole scatter s, and the confidence limit A(95) of the paleopole, we find that 20 sites (samples) or more are required to yield a paleopole with an A(95) approximate to 5 degrees based on a review of available paleomagnetic results from the Lhasa, Qiangtang and Tethyan Himalaya. Random samplings of Jurassic virtual geomagnetic poles from the Sangri area show that the Fisher mean pole with neglectable angle deviation can be obtained when sampling sites increase to 20. High-quality paleomagnetic results, with sites/samples number N/n > similar to 20-30, show that the Qiangtang, Lhasa, and Tethyan Himalaya moved northward in the Late Permian-Middle Triassic, Jurassic, and Cretaceous, respectively, and then accreted to Asia in the Late Triassic, Late Jurassic-Early Cretaceous and Paleocene-Early Eocene, respectively.