Paleomagnetism of the Baiyisi volcanic rocks (ca.740 Ma) of Tarim, Northwest China: A continental fragment of neoproterozoic Western Australia?

We report a paleomagnetic pole from the SHRIMP U-Pb zircon dated Baiyisi volcanic rocks in the Xishankou area at the northern edge of the Tarim Block, Northwest China. Rock magnetic and microscopic observations indicate that the characteristic remanent magnetization (ChRM) isolated by both thermal and alternating-field demagnetization is preserved in original single domain (SD) or pseudo-single domain (PSD) low-titanium titanomagnetite grains. The new paleomagnetic pole (Q=5) indicates that the Tarim Block was located in equatorial paleolatitudes at ca. 740 Ma and was most likely situated against Western Australia during the most of Neoproterozoic and the early Paleozoic. We suggest that the Tarim Block could be a continental fragment rifted from Western Australia during the break-up event of the Rodinia supercontinent at ca. 820-750 Ma. (c) 2005 Elsevier B.V. All rights reserved.