OROGENY AND ITS TYPE OF JUNGGAR OROGENIC BELT

The study history of orogenic belt has more than one hundred years.Various interpretations were given by different scholars:(1)Geosyncline inversion hypothesis thinks that the orogenic belt is formed as geosyncline which dues to subsidence of crust and then is folded into mountains by inversion;(2)Plate subduction collision theory considers the subduction collision between lithosphere plates is the cause of ororgeny;(3)Polygenetic hypothesis thinks that classical plate theory encounts to diffculties and challenge for explaining continental orogeny .With the new technological development of geophysical prospecting and research on deep geology,they realized that oceanic lithosphere is different from continental lithosphere in nature.Continental orogenic belt occurs not only on the plate mangin but mostly inside the plate.A series of different layered slices and intrusive sheet piled up and undergone structural defermation and crust thickening to be mountain system by stretching or moving to side direction on scale.Therefere,continental orogenic belts were formed under poly genesis and poly mechanism.The authors classified orogeny into fourteen types and twenty one orogenic modes based on the following five principles tectonics:①Property of lithosphere and its deformation pattern ;②Plate movement;③Structural system of orogeny;④Involving area of down thrust and influence on up burden plate;⑤Orogenic thickening and desguamation procedure.Especially,the soft collision, weak orogeny and basin mountain coupling model is the characteristics of the orogenic pattern of Xinjiang.