Study On The Tectonic Characteristics Of Western Qaidam Basin

Based on the structural geology, principle of seismic exploration, petroleum geology,etc, analysing outcrops, cores, drilling, well logging, seismic data, this paper has applied time-varying convolution horizon calibration, high-resolution sequence stratigraphy analysis technology in the study of structural characteristics in western Qaidam Basin.We determined the identifiable marks of lithology, logging response, seismic reflection in the top of Mesozoic and basement in the study region, based on these signs we tracked and contrasted the purpose layers, and established the sequence stratigraphic framework of the study region; We mapped the top of basement in the use of synthetic seismograms and variable velocity field, etc. Based on the interpretation of seismic data, we studied the structural features in western Qaidam basin and the relationships between the basin and the mountains. Results suggest that:western Qaidam basin can be divided into Altun fracture system, Kunbei compressoshear fracture system and western Qaidam basin compressional fracture system; There are four kinds of structural styles (compress, strike-slip, stretch and reverse) and several types of secondary structural pattern; the tectonic evolution of Mesozoic and Cenozoic in western Qaidam basin is divided into two extensional-compressional structural cycle, four structural evolution stage; According to the basement fluctuation and lithology,basement faults characteristics, sedimentary characteristics of the covers in the work region. Western Qaidam basin region is divided into Kunbei uplift and Western Qaidam depression two tectonic unit and thirteen secondary tectonic units; the relationships between Qaidam Basin and the Altun Mountains are flower-like,semi-flower-like faults contact and overlap contact, and between the Kunlun Mountains and Qaidam Basin the relationships are mainly normal faults contact in Mesozoic, and thrust faults contact in Cenozoic. Studies suggest that oil and gas reservoirs are located in the structural belts near or in the center of hydrocarbon generation depressions in the western region, while the deep fault control Mangai depression, Zahaquan-Qiekelike, Hongshi and XiaoLiangshan-Nanyishan hydrocarbon depressions.