MINERALIZATION AND PRELIMINARY DIVISION OF METALLOGENIC BELTS IN A PALEOPLATE CONVERGENCE ZONE IN THE WENDURMIAO-BAINEIMIAO AREA, INNER MONGOLIA

The author considers that there had existed a mechanism of subduction of oceanic crust of the Paleo-Asiatic ocean system beneath the lithosphere of the Sino-Korean craton since the Paleozoic in the Wendunmiao area. During the period from the Late Silurian to Early Devonian, owing to the change of the pole of subduction, oceanic crust was obducted onto transitional crust in retrograde motion and meanwhile the consumed complex was pushed onto the earth’s surface. Specific iron, chromite, copper and gold mineralizations occur in the ophiolite suite and island-arc rock series and form metallogenic belts. The belts are regularly distributcd; from oceanic crust towards the continent, belts of Fe--Cr--Cu （Au） --Au are arranged successively. They respectively contain a series of ore deposits or occurrences. Iron mineralization is represented by the Si-Fe formation on slpes of the mid-ocean ridge. Iron substances were derived from a byssal tholeiite by strong spilitization. That is to say, iron mineralization is mainly genetically related to green schist of the ophiolite suite. On the other hand, chrome minealiza- tion is related to emplaced serpentinized ultrabasic rocks of the first associa- tion of the ophiolite suite. Molybdenum-poor porphyry-copper deposits and gold deposits and their ore zones were formed in Baineimio in the immature island are occurring on simatic oceanic crust. Andesite-basalt and granodiorite-porphyry sills are host rocks of porphyry iron deposits and have close genetic relations with these deposits. The thermal system of a high-temperature axis resulting from subduction at the island arc and back-arc basin continued until the Hercynian （and even until the early Yanshanian）. Therefore, synchroneity, lag and continuity might all exist with regard to the relations of magmatism and mineralization to various processes produced during plate convergence. Under the guidance of the plate-tectonic theory, the traditional ideas about metallogenesis and directions in ore prospecting will change by great extent. Metallogenesis at both sides of the line of latitude 42°N should be related to various processes produced during plate convergence so as to promote the study and exploitation of the great metallogenic belts.