Recognition of the northern boundary of Gondwanaland using modern stratigraphic techniques

The present paper addresses the research on the attributes of the Qiangtang and Tanggula blocks and on the recognition of the northern boundary of Gondwanaland which focuses on the reestablishment of the stratigraphic framework along the margins of the Qiangtang block, referenced to the data from the 1:1000000 Gerze and Rutog Sheets and biogeographic provinces and crustal evolution of the Qinghai-Xizang Plateau.There are two stratigraphic bodies which are different in character but correlated in origin, and aligned in the eastern and western margins of the Qiangtang block:deep water-dominated sandy and muddy flysch and radiolarian silicalite-dominated sedimentary associations on the oceanward side, and shallow water siliclastic- and carbonate-dominated sedimentary associations on the landward side, implying that a northward-dipping subduction zone once occurred in the Palaeo-Tethys and once collided with the Tanggula block during the latest Permian, resulting in the formation of the late Hercynian fold belt. In addition, this paper also deals, in detail, with isotopic evolution and genesis of the skeletal fragments from various blocks of different ages, and the relationship between the initiation, development and termination of the biogeographic provinces in the Qiangtang block and rifting apart from Gondwanaland and northward drift (which led to the formation of the Neo-Tethys) and the collision of this block with the Tanggula block (which led to the termination of the Palaeo-Tethys).