| The Longmen Mountain Tectonic Belt lies on the west border of the Yangtz plate, at the transition belt between the Yangtz landmass and the Songpan landmass, also on the boundary line between Qingzang highland and Sichuan basin. There stands Maoxian-Wenchuan fault, Beichuan-Yingxiu fault, Anxian-Guanxian fault and Guangyuan-Dayi fault from the west to the east. The belt was divided into three sections , namely northern,central and southern section, along the trend at the bound of Beichuan-Anxian and Wolong-Huaiyuan.Calcite veins and surrounding rocks sampled from different parts of the Aba-Suining geological profile in the central section and the Shazhou-Baolun geologic profile in the northern section of Longmen Mountain, were analyzed in isotopic and trace elemental compositions. The models of the origin and migration of the fluid in Longmen Mountain tectonic belt have been suggested. Based on the geochemical characteristics of the trace elements of bitumen and surrounding rocks from Kangjiadong, Ningqiang and Kuangshanliang, Qingchuan, the relationship between the fluid event and the hydrocarbon conservation is disccused.Conclusions are as follows:1,There are different origins of palaeofliuds in different structural -stratigraphic unites bounded with fault zones, in central Longmen Mountain. According to the exposition feature of the quartz-calcite veins and the structure settings, the studying profile can be subdivided into five sub zones from NW to SE: Aba-Longriba orogenic subzone ( subzone 1 ), Rangkou-Heishui structural-transform subzone ( subzone 2), Maowen-Longdong ductile shear zone ( subzone 3 ), Longmenshan deckenbau subzone ( subzone 4) and Longmen Mountain thrust subzone(subzone 5 ). There are different palaeofliuds and their own origins in different subzones. In the sub zone 1, the fliuds are of highδ13C(‰) PDB, lowδ18O(‰) PDB, low 87Sr/86Sr, showing effected by atmospheric water. In the sub zone 2, the fluid in Permian Carboniferous strata is mainly from surrounding rock, and the fluid in Triassic strata is of lowδ13C, lowδ18O and low 87Sr/86Sr, showing effected by tectonic movement and deep seated material. In the sub zone 3, The fluid is from several sources, some are of siminal isotopic character to surrounding rock - marine carbonatite, and some shows effected by atmospheric water, some are of lowδ13C, lowδ18O and high 87Sr/86Sr, showing effected by both the deep and superficial substance. In the sub zone 4, the fluid source is complicated, some are similar to marine carbonatite in isotopic composition, and some are of lowδ13C ,showing effected by deep material, and some are of lowδ18O, high 87Sr/86Sr ,showing affected by atmospheric water,and some are affected by organic material, whith highδ18O and lowδ13C. In the sub zone 5, the fluids are from marine carbonatite, atmospheric water whith lowδ18O, deep substance whith lowδ13C and low 87Sr/86Sr, and from organic material whith lowδ18O and highδ13C.2,On lateral comparison, the isotopic composition of the fluid from different sub zones displays regular grading change. In general, Maowen-Longdong sub zone has been ever the activity center of the palaeofliuds in Longmenshan Belt, whith intensive and multi-stages mobility. The activity attenuated from the center towards NW and SE. Maowen-Longdong ductile shear belt and the Beichuan-Yingxiu fault zone are changing boundaries ofδ18O and 87Sr/86Sr. From NW to SE, theδ18O(‰) PDB of the fliuds changes: sub zone 1 and sub zone 2 < sub zone 3 and sub zone 4 < sub zone 5, the 87Sr/86Sr of the fliuds changes: sub zone 3 and sub zone 4 >> sub zone 1 and sub zone 2 > sub zone 5.3,The isotopic composition of fluids of the studed area revealed that the fliuds can be categorized into three structure-strata controlled system: upper-fluid-system (in Triassic), middle-fluid-system (in Devonian-Permian), and lower-fluid-system (in Cambrian- Silurian). The upper-fluid-system is relatively independent, affected by fluid from deep and atmospheric water, and has scarcely ever generated interchange process with the middle and the lower parts. The middle-fluid-system has taken interchange process with the lower in certain extent.4,In different massifs of central Longmen Mountain and its neighborhood , interchanging processes among the fluids occured. There was a fluid interchanging process of deep hot fluid, atmospheric water and formation water, between the Longmen Mountain tectonic belt and Songpan tectonicbelt, bound by Maowen fault zone. The interchange and migration of fliuds between Sichuan basin and Longmen Mountain thrust subzone occurred probably. The fluid of Longmen Mountain belt trends to migrate laterally to the basin.5,The trace elemental and REE geochemistry of bitumen veins in northern Longmen Mountain, revealed that several hydrocarbonic rocks from Sinian, Cambrian, Permian and Triassic strata may existed, and that debris-like and dry(massive) bitumen may evolve from coal, veine and impregnated bitumen may evolve from oil in Kuangshanliang area.6,The preliminary researching on the relationship between the fluid activity and oil conservation from the inorganic geochemistry, it may drow conclussion that the lateral side of Maowen fault zone is a relatively open system in which fluid travel relatively. It is disadvantageous to oil conservation. The area between Beichuan fault and Anxian fault is relatively closed environment. The fluid is compressional. It is favourable for oil conservation relatively. In Kuangshanliang erea the bitumne is from several resources, and effected by structure, deep fluid and shallow source at the same time, it is unfavourable for the oil conservation. In Kangjiadong area, Sinian strata is relatively steady, transformation of the fliud is relatively week, it may beneficial for oil conservation.
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