| The Qiangtang Basin, as an eyed-type, located in the hinterland of Qinghai-Tibetan plateau, is tectonically situated between Yanghu-Jinshajiang river suture and Bangong Lake-Nujing suture. The total area is about 250000km~2. Along E90°, according to basin texture, sedimentary filling characteristics, basin development, and geophysical information in deep, the Qiangtang Basin can be divided into the east and the west parts. Because of bad working environment, poorly previous researches can be cited and referred, thus, different even debated viewpoints on basin formations, evolution and later deformation etc. exist.The east of the Qiangtang Basin, located in a superimposed area among the Eurasian continent, Gondwanaland and western edge of the Yangtze Plate, is a main region of the Chinese tectonic framework. For its special lithospheric texture and complicated structural evolution, the Qiangtang Basin has been realized as a typical region for studying the Qinghai-Tibetan oceanic lithospheric growth, ocean-continent subduction, continent-continent collision, intracontinent orogeny and crustal material re-distribution, and plateau formation and uplift, etc. The basin sedimentary filling and evolution were controlled by the poly-cycle orogenic processes of Eurasian and Gondwanaland plates in south and north, and also constrained by different tectono-paleo-geographic conditions and geodynamic processes in various periods. The basin evolution shows extensive differentiation and complicated basin-range coupling.In this thesis, guided by activation, unit, stage, layered and basin-range coupling theories, using theory and method of basin sedimentary and basin structural analysis, combining structure-sedimentation-magmatism with chronology and geophysical references, based on systematically studying Meso-Cenozoic petrological series, sedimentary sequences and their time-space distributions, fossils, and strata relationships, the Qiangtang Basin is divided as several tectonic units: south and north Qiangtang depressions, Tangula uplift and different sub-uplift and down. In view of sedimentary filling sequences and changing features in different tectonic units of the basin, as well sedimentary systems and their time-space distributions, sedimentarysources and tectonic conditions in controlling basin formation and evolution, the author draws different tectono-paleo-geographic diagrams in a time intervals from late Triassic to late Cretaceous. Several concluding remarks are as follows. (l)The east of Qiangtang Basin is a Meso-Cenozoic multi-superimposed basin. The Duoma depression is a continental surface basin on the passive continental margin which has a basement of late Triassic tectonic schists and superimposed by the Jurassic-early Cretaceous sedimentation. Later, during the early Cretaceous time, it has been transformed as a foreland basin, and since late the Cretaceous, it has been connected with the Suoxian-Zuogong depression. Totally, during the intracontinental orogenic processes, it experienced multiple compression-depression evolution of sedimentary filling. (2) The Suoxian-Zugong depression is a foreland basin developed during the late Indocinian stage and based on the trough-arc-oceanic system. (3) The north Qiangtang depression was based on the Varician Kaixinling-Zaduo uplift, and followed by late Triassic Changdu foreland basin formation, as well early Jurassic north Qiangtang fault-depression. During the middle Jurassic time, the north Qiangtang and Suoxian-Zuogong depressions were combined with as one depression, and which built-up a huge Qiangtang-Changdu depression basin. This depression basin, than later, was transformed as a fault depression in the Cenozoic time. (4) The author analyzes the formation and tectonic transformation as well evolution of the different basins since the early Mesozoic time to late Cretaceous.
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