Paleomagnetic constraints on the tectonic rotation of the southeastern margin of the Tibetan Plateau

In this paper we present a comprehensive summary of the geological evolution of the southeastern margin of the Tibetan Plateau and a detailed reanalysis of previously published paleomagnetic data. We focus on the Cenozoic, which represents a period during which the southeastern margin of the Tibetan Plateau was one of the most active tectonic regions due to the India-Eurasia collision. Our analysis indicates that, since the Cenozoic, with respect to the stable Eurasian block, the Shantai terrane experienced a clockwise rotation of similar to 20 degrees-80 degrees, with some areas experiencing clockwise rotation by as much as 135 degrees, and the rotation of the central part of the terrane is higher than that in the north and south of the terrane; the IndoChina terrane rotated similar to 30 degrees clockwise and the rotation of the Chuandian terrane decreased from 30 along the longitude 102 degrees E from south to north. Of the three terranes only the Shantai terrane recorded a similar to 8 degrees southward translation. The variation of rotation versus time indicates that the main rotation of the southeastern margin of the Tibetan Plateau occurred between Eocene and mid-Miocene, which is in accordance with the sinisterly slip of the Ailao Shan-Red River fault zone. This complex tectonic history, revealed by paleomagnetism, cannot be fully explained by the commonly accepted models for the formation of the Tibetan Plateau, such as crustal thickening, lateral extrusion or lower crustal flow. Reliable Cenozoic paleomagnetic data in the southeast margin of Tibetan Plateau are scarce. Therefore, to better evaluate the effects of the India-Eurasian collision on the southeastern margin of the Tibetan Plateau, additional and more detailed paleomagnetic studies of Cenozoic rocks from this region are essential.