| Sichuan basin as one of the important oil and gas basins in China, the couplingrelationship between Sichuan basin, qinghai-tibet plateau, Longmen Mountain aswell as other peripheral ridges and ranges has received extensive attention of thegeological community. In the past, the foreland basin was a key area of oil and gasexploration, but with the deeper study of orogenic belt, orogenic belt of oil and gasexploration is more valued, the formation mechanism of the tectonic characteristicsand structure of orogenic belt and tectonic evolution history naturally became themain content of structural geology research. Due to the limitation of technical meansand the sichuan basin’s complex and special tectonic location, insufficient knowledgeis also a large problem, such as the nature of the different evolution stages of the basin,characteristics of superimposed basins, the difference of dynamic mechanism,coupling relations, the peripheral orogenic belt of complex tectonic characteristics andhydrocarbon migration and accumulation and so on. Among them, to clarify thecomplex tectonic characteristics of orogenic belts is the priority of exploration,because it has become the bottleneck of restricting the oil and gas exploration work.Thus, we want to breakthrough, we must research the tectonic deformationcharacteristics of orogenic belts and the tectonic evolution history, The developmentof the research has important guiding significance for the mineral resources survey inthis area.The Longmen Mountain is located in the western China, lie in the northwest ofsichuan basin edge, West Sichuan Plateau is in the west. The landscape and tectoniccharacteristics is different On both sides of the Longmen Mountain. usually accordingto the difference of tectonic and sedimentary, the Longmen Mountain is divided intonorth-section, mid-section, and south-section. The north section of LongmenMountain starts from the north side of Hanwang in Mianzhu city,while the southsection begins at the south side of Guankou in Dujiangyan city. Predecessors mainlyconcentrated on the study of the middle section and the north section, with the southsection left out. The target area of current research is located in the southwest of sichuan basinedge, lie in the south-section of Longmen Mountain. Sanhechang, Lianhuashan andZhangjiaping structure are the main structure we need to research. Xujiahe Stratumand Leikoupo Stratum are the target series of strata of this research. in addition tofield investigation, combines geological profiles, well drilling, well detecting, andseismic cross-section profiles to build new theories and new approaches thusproviding favorable conditions to conduct analysis on tectonic styles and to built amodel for the complex tectonics of the front area of Longmen Mountain, through thestudy on compressional tectonics, extentional tectonics and fault-related folds etc.And subsequently undertake elaborate analysis on faulting features, as well asgeologic trap features through deeper study of regional tectonic background, seismicinterpretation and balanced cross-section restorations, therefore the tectonictransformational properties of the front area of Longmen Mountain and tectonicdynamic mechanism of the target area will be utterly and systematically analyzed toeventually acquire the tectonic geological recognition on tectonic transformationalfeatures which complies with the actual situation.Following are the major tasks and the acquired knowledge of this research:1. Cap the4seismic sections of Gaojiachang tectonics, sort out the section andplane distribution properties of the surface structure, lay solid foundations formanufacturing building models and comprehensive interpretation of seismic geologyon the basis of surface geological research.2. Discovered that the superficial layer in south section of Longmen Mountainmainly comprises thrust tectonic styles, and wrench tectonic styles, through thecombination of geological field work, analysis of regional tectonic background,seismic section analysis, with the horizontal and vertical distribution characteristics ofsurface and underground structure.3. Combined comprehensive drilling stratification, the surface geologyinvestigation, the analysis of tectonic style, with seismic reflection characteristics tobuild Sanhechang,Zhangjiaping, Lianhuashan tectonic geological model accordingto01GSZ06border,01GSZ08border,02LHS14border. These three structures are theflower-like tectonics jointly formed by the major faults and numerous subsidiaryfaults.4. Under the instruction of tectonic geology model, comprehensive interpretationfor seismic geology on the43seismic detecting lines which are beyond the border ofSanhechang, Zhangjiaping and Lianhuashan was conducted. Also a chronical tectonic map was drawn up for Xusandi Border and Xujiahe Border which are locatedin.Sanhechang, Zhangjiaping and Lianhuashan.5. Through the study of tectonic deformation characteristics in the study area,find that fault activities become more and more intense, the horizontal displacementcaused by the fault increases gradually. The reduced rate of fold deformation in theprincipal part of the structure is bigger, smaller in the end.6. Ascertained the trap characteristics and the fault characteristics byreinterpreting two-dimensional lines of target area. |
PDF Full Text Request