Evolution And Feature Of Thermal Structure And Thermal Interaction In Qiangtang Basin Of The Northern Tibet

This paper based on the comprehensive study the thermal structure of Qiangtang Basin; systematic summarized the thermal structure, which studied in a lower degree in this area. The paper also emphasised the pivotal function of the thermal structure rising and evolution of the basin of Qinghai-Tibet plateau; this method improved and raised the study in the Qiangtang Basin.Based on the summarize study of mantle plume and thermal structure, the paper divided the thermal structure into several pieces. By physiognomy feature, it could be divided into three types of thermal structure: positive dome model, negative collapse model and border dome core collapse model. Based on the depth degree or magma-thermal influenced, it could be divided into five types of thermal structure: (ancient) geothermal anomaly focus region model, superficial volcano eruption hydro-thermalism and hypabyssal intrusive model, thermal anticline (thermal dome) model, mid-deep intrusive model, deep mantle (crust) thermal plume model; and put forward a perfect model of the thermal structure. There are many interaction system could be induced into a systematic thermal interaction, include: Ocean-continent system, basin-mountain interaction, superficial and mid-deep crust-mantle interaction, crust-mantle commingle interaction, vertical thermal interaction (delamination) etc.. All these work make a new way for the study of basin dynamics, discussed the research method of the thermal structure. Based on predecessors research by geological-geophysical synthesized studying and three-dimensional technique, draw up west, middle and east three composite profiles, explanation of the structure model in different level including surface, middle and deep of the basin, finally concluded in homogeneity of the basin is show by belting in south-north trend, block-faulting in east-west trend and vertical sphere-laying. Set up a typical basin crust frame chart of west, middle and east sector individually.For column zone where vertical quite low resistance anomaly exists in deep basin, zone where specific resistance is less than 40 m in shell, they are related to heat power action in deep place which is resemble to mantle (crust) sub plume. The layer of low-resistance in the crust has three existence manners. The summit interface fluctuates a lot and it is not uniform in the cross direction. Different zone block in the basin has different construction. Cold and heat shells are at intervals. Crust behaves as hot, light, flowing and thicker, however, mantle behaves as cold, weight, and harder, multi-phase and deep mantle.The special aerial magnetism, gravity and MT at Chasang Segment in the western uplifting district show that it is superposed by two or three large-scale south dipping structural block with east-west strike. The closure of Bangong Lake-Dingqing limited Ocean and the further gathering of neighboring blocks later form it.There is a north-north-east negative anomaly belt of aerial magnetism in the middle-east part of the basin, which could be displayed by the aerial magnetism of commutative field, upwardly continuation, LVT in earthquakes, the experimentation of granite liquation (demagnetization) , the distribution of Neozoic era volcanic rock, earthquake, hot spring and ground feature. The anomaly shows the blocking in east-west direction, and it is also associated with intense activity of deep heat interaction and the development of the crust-mantle mixed layer in the North Qiangtang.We generally consider that the heat power in the deep of the basin is active, and the magmation is frequent, and that the type of the thermal structure is various.The analysis of the thermal structure is mainly focused on several different representative examples. (1) The first analysis is thermal structure of the collapse type in Quemocuo. There each group in Jurassic system is well developed, and there are two settlement-conglomeration centers of the period of Quemocuo and Xueshan. In prophase there existed thermal and magma activity, and before the...