New paleomagnetic results from the Yangzhuang Formation of the Jixian System, North China, and tectonic implications

摘要

A paleomagnetic study was carried out on the Yangzhuang Formation (approx 1350 Ma) of the Jixian System in the North China Block (NCB). Detailed stepwise thermal demagnetization isolated two components. The soft component (component A) was interpreted as a remagnetization in the recent geomagnetic field. The hard component (component B) with higher unblocking-temperatures was carried by hematite. Its site-mean direction is D/I = 77.6 deg/-24.3 deg (k = 5.4, a_(95) = 18.3 deg, N = 15 sites) before, and D/I = 72.2 deg/11.5 deg (k = 24.6, a_(95) = 7.9 deg ) after tilt correction. It passes a fold test (Mesozoic folding) at 99 percent confidence level and reversal test at 95 percent confidence level. The corresponding pole locates at 17.3 deg N, 214.5 deg E (dp = 4.1 deg, dm = 8.0 deg). A best fit of paleomagnetic poles from the NCB, Baltica, Siberia and the apparent polar wander path for Laurentia suggests a long-lived connection between these paleo-continents between approx 1800 and 1350 Ma.