Outline of the tectonic evolution of southwestern China

Abstract

Five tectonic units are represented in southwestern China. They are: 1. (I) the eastern Kunlun fold belt. 2. (II) the Yangtze paraplatform. 3. (III) the South China paraplatform. 4. (IV) the western Yunnan fold zone. 5. (V) the Himalayan fold zone. The westernmost region of the Yangtze paraplatform of the Chinese plate and the western Yunnan fold zone of the Southeast Asia plate occupy much of southwestern China. They are separated by a NW-SE trending suture line marked by deep faults, ultramafic complexes, and melanges. The Yangtze paraplatform is characterized by Precambrian rocks, Paleozoic sedimentary rocks, Permian basalts, Triassic continental deposits, and abundant hot springs. West of the suture line, the Southeast Asia plate is characterized by the Transverse Ranges, inverted Jurassic geosynclinal folded belts of deep-water flysch deposits. During the Late Triassic, the Chinese plate and the Southeast Asia plate drifted toward each other and eventually coalesced. Later, during the Late Jurassic, the Tarim and Tibet blocks also drifted toward the Chinese plate, finally coalescing with the western part of the Chinese plate. Finally, the collision of the Indian plate with the Tibetan block in Late Cretaceous time, squeezed the northern tip of the Southeast Asia plate laterally against the Yangtze paraplatform.