The Tarim Craton in the Northwest of China

Abstract

ABSTRACT The Tarim Craton (or Tarim Block) is geographically located in the Northwest of China and tectonically between the Central Asian Orogenic Belt (CAOB) to the north and the Tethys to the south, which underwent a secular Precambrian evolution history from Ecoarchaean to Ediacaran. Owing to its marginal positions both in the Columbia (or Nuna) and Rodinia supercontinent configurations, it could play a key role in understanding the geodynamics of the assembly and break-up of the Precambrian supercontinents. This paper aims to present a critical review on the comprehensive synthesis of the Tarim Craton, detailing the Precambrian evolution processes and discussing its coupling with the Precambrian supercontinents. The Tarim Craton shows a typical plateform-like and double-layered structure, comprising the pre-middle Cryogenian basement with the middle Cryogenian-Ediacaran cover sequence. During its protracted basement evolution, diverse types and multiple stages of pre-Ediacaran intrusions were emplaced in the basement. Since Pleoproterozoic to early Cryogenian, crust reworking, rather than juvenile crust addition, played a key role in the final cratonization of its basement. Despite the final cratonization of the Tarim completed in the middle Cryogenian, both the bulk-rock Sm-Nd and zircon Lu-Hf isotope compositions demonstrated that its crust mainly formed in Archaean. Its characteristics of sedimentary features, metamorphic temporal-spatial architecture, the multiple phases and diverse types of intrusions reveal that the Tarim Craton is possibly composed of two main terranes with distinct features, i.e. the Northern Tarim Terrane (NTT) and the Southern Tarim Terrane (STT). It has been suggested that the STT could be a continental fragment that has drifted from West Africa, while the NTT shows a significant affinity with the India–North China Craton before Calymmian. Both were involved in the assembly and break-up of the Columbia supercontinent, and amalgamated during the assembly of the Rodinia. At the same time, it docked at the northern margin of Australia in the middle Cryogenian. Nevertheless, the subduction along the northern margin of the NTT continued at least until ca. 760 Ma. The voluminous 820–760 Ma diverse-type intrusions in the NTT have been ascribed to a genetic relation in the interaction between the circum-Rodinia subduction and the Rodinian superplume. The upwelling of the Rodinian superplume terminated the long-lasting subduction along the northern margin of the Tarim Craton. Since 740 Ma, being consistent with the break-up of the Rodinia, the Tarim Craton started drifting from the Rodinia supercontinent. The transition from signature to the passive continental margin of the middle Cryogenian-Ediacaran (for its cover sequences) rules out the possibility of the circum subduction along its northern margin lasting to early Palaeozoic. Additionally, with the Rodinia breaking up into the assembly of the Gondwana, the Tarim Craton, together with other continents in Eastern Asia, had docked at the margin of the Eastern Gondwana in early Palaeozoic.