A detailed field-based remote sensing interpretation in this study revealed abundant recent seismic surface ruptures on the southern margin of the Longshoushan Fault, including fault scarps, mole tracks and displacements of river channels. The total length of the surface rupture zone is over 20 km. The most recent vertical and horizontal displacements of the late Quaternary geomorphic markers fall into the range of 0.35~4 m and 0.3~1.9 m, respectively. The southern Longshoushan Fault is a high-angle thrust fault, and it only exhibits left-lateral strike-slip on the west end. Revealed by profile and trench along the surface rupture, the southern branch of the Longshoushan Fault Zone has gone through several earthquake events since the Holocene, and the latest one happened around 3.96 ka. By comparing with the strongest earthquake recorded in this region, it is suggested that the 1954 M_S 7¼ Shandan earthquake may have caused the newly discovered surface ruptures, which developed along both the southern and northern branches of the Longshoushan fault zone, presenting a positive flower structure at the shallow surface. This coseismic displacement distribution mostly is found in strike-slip earthquakes in previous studies, but it is found in a thrust earthquake this time. The discovery of coseismic surface rupture on the southern branch of the Longshoushan Fault Zone will throw light on the focal mechanism and rupture pattern of the 1954 Shandan M_S 7¼ earthquake.

Single-grain U-Pb dating of detrital zircons is regarded as an efficient and effective technique to differentiate the contribution of discrete sources. However, its application to the extensive Chinese Loess Plateau (CLP) yields rather complex information in provenance discrimination. The Xining loess was deposited in the Northeastern Tibetan Plateau (NETP), and the detrital zircon U-Pb chronology study can not only obtain provenance information but also provide an important basis to discuss the contribution of the detrital materials from the Northern Tibetan Plateau (NTP) to the CLP. Results of the detrital zircon morphology suggest that zircons may have undergone intense physical weathering and multiple recirculations, and may also indicate the high complexity of the source. Detrital zircon U-Pb age results from different sedimentary layers of the Xining loess reveal there are no obvious temporal variations in the provenance of the Xining loess since~1.3 Ma and materials may ultimately be eroded from the NTP and the Central Asian Orogenic Belt (CAOB), although the relative contribution of detritus from the two sources may slightly vary through time. The U-Pb age spectra of the Xining loess are highly similar to that of typical loess sites in the western-central CLP, suggesting that the provenance areas of the CLP and the Xining loess may be largely consistent, but the possibility of a small difference of provenance cannot be ruled out.

To ensure the national demand for gas supply and peak shaving, a project of capacity expansion is proposed for the Xiangguosi underground gas storage (UGS). A geologic integrity evaluation is urgently needed to optimize the upper operating pressure and ensure the long-term safe operation. Thus, based on the geological, seismic, well logging, and dynamic monitoring data as well as the indoor core experimental data, 3D static and 4D geomechanical models were established for this UGS. Some geomechanical characteristics of the geological body were analyzed. The stability of the caprock, base, and fault under different reservoir pressure was individually simulated and evaluated as well. The results show that, both the caprock of the Liangshan Formation and the base of the Hanjiadian Formation may produce a little formation deformation during the operation; the five reservoir-controlling faults have no risk of fault activation during the early UGS operation under current stress conditions, and their sealing performance is good; when the reservoir pressure is higher than the original formation pressure of 6 MPa, the integrity of the Xiangguosi UGS is at risk of instability. This research accurately and quantitatively evaluate the operation safety of the Xiangguosi UGS under the influence of dynamic stress field, which has important guiding significance for the optimization of its operation plan.

In oil and gas seismic exploration, when the seismic wave propagates in the earth medium, it will encounter obvious absorption and attenuation, resulting in the main frequency of the seismic signal shifting to the low-frequency end. The frequency band narrows and the phase is distorted, which restricts the resolution of seismic exploration to identify thin layers. To obtain a seismic image with higher resolution, this paper introduces a method with effective Q estimation in the imaging domain of seismic reflection data and uses the estimated Q-value to compensate for the attenuation effect through migration to achieve high-resolution imaging. This method introduces the concept of effective Q-value into the time domain. In the time window of the initial viscoelastic time migration image, the effective Q parameters in the time domain are determined through the compensation effect of the data in the time window. Then, the time-depth conversion function is obtained by calculating the imaging ray in the layer velocity in the depth domain, and then the time-depth conversion is carried out for the Q parameters converted to the layer Q-value in the time domain. At last, the key parameter is used as the input of viscoelastic prestack depth migration for viscoelastic compensation imaging of complex structures. Finally, this paper uses the real seismic data from eastern China to verify the effectiveness of the method. The final results show that the process and method developed in this paper can better realize the Q-value modeling and imaging domain compensation in the depth domain, and realize the high-resolution imaging of complex structures.

Significant discoveries and breakthroughs have been made in the shale gas exploration in the southern slope zone of the Huangling uplift, periphery of the Sichuan basin. Based on previous research results, regional geological data, geophysical data and drilling data, it is proposed that the uplift has experienced four structural evolution stages since the Proterozoic, including the formation of crystalline basement in the pre-Sinian period, the intrusion of rock mass in the early Sinian period, the alternation of subsidence, deposition, uplift and denudation in the Sinian-middle Jurassic period, and the rapid uplift in the late Jurassic-Paleogene period. This distinctive structural evolution history of the Huangling uplift plays an important role in the shale gas accumulation, in which the third stage assures the appropriate depth and moderate thermal evolution and porosity, and the strong basement formed in the first stage protects the relative integrity and continuity of the sedimentary cap. We also found some uplifts with similar structural evolution history, basement and cap features as the Huangling uplift in the middle and lower Yangtze River area, such as the Xuefeng uplift and Qianzhong uplift on the periphery of the Sichuan Basin, and the Huoqiu uplift in the southern North China Basin. Through further geological, geophysical and drilling work, oil/gas reservoir may be discovered in the above uplifts.