An apparent polar wander path from the Tarim Block, China

Abstract

The apparent polar wander (APW) path from the Tarim Block consists of Devonian ( λ = 16° N, φ = 165° E, A 95= 4°), Late Carboniferous ( λ = 41° N, φ = 160° E, A 95 = 4°), Permian ( λ = 61° N, φ = 177° E, A 95= 9°), Early Triassic ( λ = 69° N, φ = 183° E, A 95 = 11°) and Jurassic/Cretaceous ( λ = 65° N, φ = 214° E, A 95 = 6°) poles. On the basis of this APW path, we conclude that Tarim rode on a plate subducting under the Kazakhstan plate between Devonian and Permian times. By the end of the Permian, subduction had almost finished. Early Triassic poles from Tarim, Siberia, North China and South China are discordant, indicating post-Early Triassic relative motions among them. Cretaceous paleomagnetic poles from Tarim, North China and South China, however, are consistent, suggesting that China has been a coherent tectonic unit since Cretaceous time. The shape of the APW path from Tarim is similar to that of Siberia, except that Tarim's APW path is systematically displaced to the east. A 26° clockwise rotation of Tarim's APW path about the Euler pole λ = 60°N and φ =14°E reconciles these two APW paths. Tarim has moved northeastward some 2000 km relative to a fixed Siberia since the Cretaceous. This northeastward motion of Tarim with respect to Siberia agrees well with the overall Cenozoic tectonic style of Asia. Most of southern China has been pushed eastward to give way to the penetrating Indian continent. East-west- and northeast-trending left-lateral strike-slip faults north of the Tarim Block have been documented; however, the exact amounts of displacement along these faults are not well known. Using paleomagnetic data from Tarim, we will also discuss the tectonic evolution of terranes in central Asia and the amount of continental shortening in the Tibetan plateau.