THE MAGNETIC PROPERTIES OF CRETACEOUS VIOLET SANDSTONES ON FENGHUO MOUNTAINS REGION IN QINGHAI-TIBET PLATEAU AND ITS SIGNIFICANCE
Dong Xuebin Yang Huixin Cheng Liren Li Pengwu (Department of Geophysics)
Ferrodomite is the main magnetis carrier in the Cretacous violet sandstone on Fenghuo mountains. It's curie point is about 500℃. When demagnetic temperature rise up to 600℃, ferrodoiornite begins dissociating and forms magnetite, this results in intensification of the specimen magnetism, and modifies specimen's primary mineral component. Thus, primary steady remanence can be determined on the basis of intri-insic remanence at the temperature lower than curie point. The Cretaceous palaeomagnetic data indicates that the Bayanhar terrane in Qinghai-Tibet plateau had a larger movement to the north after Cretaceous.