The Research On The Tibetan Plateau's Cenozoic Magmatism Based On GIS

The Tibetan Plateau is still an active orogenic belt on the earth induced by continentalcollision. To establish the frame of accurate chronology is the base for the research on formationand evolution of the Tibetan Plateau. Owing to the different attributes of the data, absent analysisof spatio-temporal correlation of geological events and so on, it is still a subject of widespreadcontroversy on the frames of chronology which are all established on bases of igneous rocks.Therefore, we apply GIS to the research of the Cenozoic magmatism in Tibetan Plateau. Byextracting geological information and establishing a spatial database of igneous rocks, we set upa primary information platform with ArcGIS 9 for synthetically studies of the Tibetan Plateau.Also make the new space technology successfully be used in the research on Cenozoicmagmatism in the Tibetan Plateau.After the statistical analysis of 436 isotopic ages of sample spots what we collected, wesuggest that the critical time of Cenozoic evolution of Tibetan Plateau is 65Ma, 45Ma, 27Ma,17Ma, 9Ma and 4Ma. Hereby, we analyze the spatio-temporal distribution of the TibetanPlateau's Cenozoic igneous rocks in 6 time episodes (65-45Ma, 45-27Ma, 27-17Ma, 17-9Ma,9-4Ma and 4-0Ma). The analysis results show that the Cenozoic igneous rocks obviously spreadheterogeneously.In this paper, we apply the technology of space analysis, like Contour and SpacialInterpolation in GIS, to the study of the Tibetan Plateau's Cenozoic magmatism. After theinvestigation of small regions of 6 time episodes and the whole Plateau, we find that thespace-time migration of the Cenozoic magmatism has two axes: the Lhasa block and the Lagalaarea of South Qiangtang. It is noted that the magmatism around the Lhasa block played a leadingrole to affect the spatio-temporal migration of the whole Tibetan Plateau. Besides, our researchindicates that the Cenozoic magmatism in the Tibetan Plateau have migrated at four directions,namely E, ES, W and WN. Migration to the east is the most obvious trend we can see.By using the GIS, a technology of space analysis, we review the time-space inhomogeneityof the Cenozoic magmatism in the Tibetan Plateau. According to the migrating trends by Contourand Spacial Interpolation ect., we conclude that the Cenozoic igneous rocks in Tibetan Plateaupresent three distribution forms: the magmatic belt paralleling the Indus-Tsangpo suture zone, themagmatic belt along the deep and huge faults, and the scattered magmatism in north TibetanPlateau.