How ophiolitic mèlanges can be defined as sutures is controversial with regard to accretionary orogenesis and continental growth.The Chinese Altay,East junggar,Tianshan,and Beishan belts of the southern Central Asian Orogenic Belt(CAOB) in Northwest China,offer a special natural laboratory to resolve this puzzle.In the Chinese Altay,the Erqis unit consists of ophiolitic melanges and coherent assemblages,forming a Paleozoic accretionary complex.At least two ophiolitic melanges(Armantai,and Kelameili) in East Junggar,characterized by imbricated ophiolitic melanges,Nb-enriched basalts,adakitic rocks and volcanic rocks,belong to a Devonian-Carboniferous intra-oceanic island arc with some Paleozoic ophiolites,superimposed by Permian arc volcanism.In the Tianshan,ophiolitic melanges like Kanggurtag,North Tianshan,and South Tianshan occur as part of some Paleozoic accretionary complexes related to amalgamation of arc terranes.In the Beishan there are also several ophiolitic melanges,including the Hongshishan,Xingxingxia-Shibangjing,Hongliuhe-Xichangjing,and Liuyuan ophiolitic units.Most ophiolitic melanges in the study area are characterized by ultramafic,mafic and other components,which are juxtaposed,or even emplaced as lenses and knockers in a matrix of some coherent units.The tectonic settings of various components are different,and some adjacent units in the same melange show contrasting different tectonic settings.The formation ages of these various components are in a wide spectrum,varying from Neoproterozoic to Permian.Therefore we cannot assume that these ophiolitic melanges always form in linear sutures as a result of the closure of specific oceans.Often the ophiolitic components formed either as the substrate of intra-oceanic arcs,or were accreted as lenses or knockers in subduction-accretion complexes.Using published age and paleogeographic constraints,we propose the presence of (1) a major early Paleozoic tectonic boundary that separates the Chinese Altay-East Junggar multiple subduction systems of the southern Siberian active margin from those of the northern Tarim;and (2) a major Permian suture zone that separates the Tianshan-Beishan from the northern active margin of the Tarim Craton.These new observations and interpretations have broad implications for the architecture and crustal growth of central Asia and other ancient orogens as well. How ophiolitic mèlanges can be defined as sutures is controversial with regard to accretionary orogenesis and continental growth. Chinese Chinese Altay, East junggar, Tianshan, and Beishan belts of the southern Central Asian Orogenic Belt (CAOB) in Northwest China, offer a special natural laboratory to resolve this puzzle.In the Chinese Altay, the Erqis unit consists of ophiolitic melanges and coherent assemblages, forming a Paleozoic accretionary complex. At least two ophiolitic melanges (Armantai, and Kelameili) in East Junggar, characterized by imbricated ophiolitic melanges, Nb- enriched basalts, adakitic rocks and volcanic rocks, belong to a Devonian-Carboniferous intra-oceanic island arc with some Paleozoic ophiolites, superimposed by Permian arc volcanism. the the Tianshan, ophiolitic melanges like Kanggurtag, North Tianshan, and South Tianshan occur as part of some Paleozoic accretionary complexes related to amalgamation of arc terranes. the the Beishan there are also several ophiolitic melanges, includin g the Hongshishan, Xingxingxia-Shibangjing, Hongliuhe-Xichangjing, and Liuyuan ophiolitic units. More ophiolitic melanges in the study area are characterized by ultramafic, mafic and other components, which are juxtaposed, or even emplaced as lenses and knockers in a matrix of some coherent units. the tectonic settings of various components are different, and some adjacent units in the same melange show contrasting different tectonic settings. formation of of various components are in a wide spectrum, varying from Neoproterozoic to Permian. herefore we can not assume that these ophiolitic melanges always form in linear sutures as a result of the closure of specific oceans. Often the ophiolitic components formed either as the substrate of intra-oceanic arcs, or were accreted as lenses or knockers in subduction-accretion complexes. Published published age and paleogeographic constraints, we propose the presence of (1) a major early Paleozoic tectonic boundary that separates the Chinese Altay-Eas tJunggar multiple subduction systems of the southern Siberian active margin from those of the northern Tarim; and (2) a major Permian suture zone that separates the Tianshan-Beishan from the northern active margin of the Tarim Craton. The new new observations and interpretations have broad implications for the architecture and crustal growth of central Asia and other ancient orogens as well.