Paleogeography of the northwestern China blocks on the periphery of Rodinia in the early Neoproterozoic: New ∼895 Ma paleomagnetic insights

The paleogeographic positions of the northwestern China blocks, including the north Tarim block (NTB), south Tarim block (STB), Altyn Tagh block (ATB) and Qaidam-Qilian block (QQB), in the Rodinia supercontinent are still enigmatic. We carried out combined geochronological and paleomagnetic studies on the early Neoproterozoic mafic dikes in the North Altyn Tagh terrane (NAT) of the northern ATB. One diabase dike was dated at ∼895 Ma by using the SHRIMP baddeleyite dating method. All of the paleomagnetic core samples, including 214 samples from 16 dikes and 33 samples from their host rocks were subjected to stepwise thermal demagnetization. After removing a low temperature component acquired under a recent geomagnetic field, a high temperature component (HTC) was identified between 450 °C and the unblocking temperature (∼580 °C) which is mainly carried by pseudo-single-domain magnetite. Both the presence of reversals and partial baked-contact test support that the HTC is primary remanent magnetization. The paleopole has averaged out paleosecular variations and has no resemblance to younger paleopoles from the region. Based on the comparison of our new ∼895 Ma paleopole and the global cotemporaneous paleomagnetic data, along with the geological evidence, we proposed a new paleogeographic model, in which the STB, ATB, QQB and the north China craton were located next to the northwestern side of Laurentia, as the low latitudinal neighbors along the periphery of Rodinia.