TECTONIC NATURE AND TECTONIC EVOLUTION OF THE "XUEFENG OLDLAND"IN THE CALEDONIAN STAGE

The tectonics problem of the "Xuefeng oldland" is a focus in the regional tectonic study of South China.In the Sinian to Early Paleozoic,the oldland was a part of the southeastern passive continental margin of the Yangtze oldland,where the sediment association consisting mainly of slope factes was deposited. In the Caledonian,it became a marginal fold-fault mountain system of the Yangtze oldland but still remained as a part of the Yangtze block rather than the conventionally called South China Caledonian fold belt. This oldland was formed as a result of closure of the Caledonian Wuyi-Yunkai backarc basin of South China,assembling of the Yangtze block and the Cathaysian block and continent-arc collision orogeny and was a constituent part of the South China Caledonian continent-arc collision orogenic belt. Its main tectonic style is parautochthonous thrust-imbrication nappe structure of the foreland belt.