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

A paleomagnetic study was carried out on the Yangzhuang Formation (~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°/-24.3° (к = 5.4, α₉₅ = 18.3°, N = 15 sites) before, and D/I = 72.2°/11.5° (к = 24.6, α₉₅ = 7.9°) after tilt correction. It passes a fold test (Mesozoic folding) at 99% confidence level and reversal test at 95% confidence level. The corresponding pole locates at 17.3°N, 214.5°E (dp = 4.1°, dm = 8.0°). 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 ~1800 and 1350 Ma.