Widespread Cenozoic (?) remagnetization in Thailand and its implications for the India-Asia collision

Paleomagnetic study of 13 sites from the Khorat plateau in Thailand spanning ages from the Devonian to the Jurassic, and reappraisal of published results from the Triassic to the Cretaceous show that most of the Indochina block suffered complete remagnetization after the Triassic and possibly after the Cretaceous, most likely at the time of the collision of India and Eurasia. The paleodirection associated with this remagnetization is consistent with the contention that Thailand was a part of Eurasia at that time and that it has suffered some 20° of clockwise rotation subsequently. Also consistent is the observed azimuthal difference of Mesozoic fold axes on either side of the Red River fault, as is the early geometry of and sense of motion on this fault. Re-interpretation of late Neogene data suggests that rotation may have continued into the Neogene. The remagnetization event prevents the determination of paleopositions of Thailand prior to the Cenozoic, but carries great interest in the frame of the extrusion tectonics concept.