Palaeomagnetic data about southern Tibet (Xizang) — I. The Cretaceous formations of the Lhasa block

• Published in: Geophysical Journal of the Royal Astronomical Society Vol. 73; no. 2; pp. 507 - 521
• Main Authors: Westphal, Michel, Pozzi, Jean-Pierre, Zhou, Yao Xiu, Xing, Li Sheng, Chen, Xian Yao
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.05.1983
• ISSN: 0956-540X; 0016-8009; 1365-246X
• DOI: 10.1111/j.1365-246X.1983.tb03327.x

A palaeomagnetic study of Middle to late Cretaceous redbeds from Linzhou basin (Lhasa block), north of the Yarlung Zangbo suture zone, gives a stable palaeomagnetic direction of magnetization with a positive fold-test: six sites, 57 samples, D=333°, I=38°, k=78, α95=8°, pole 64°N, 348°E. We discuss the problem of a possible remagnetization but consider that this direction of magnetization gives a good approximation for the palaeolatitude of the Lhasa block during Middle to late Cretaceous time. Results from more recent Tibetan formations are also presented: late Cretaceous to Palaeocene sediments and volcanics give a lower palaeolatitude of 10°N and but more recent andesites have emplaced about 30°N, close to the present-day latitude. An interpretation is proposed whereby the Lhasa block, which was a part of Asia in the early Cretaceous, has undergone first a southward motion accompanied by an anticlockwise rotation and then, after the Palaeocene, a northward motion under the constraint of the colliding India.