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Abstract: This study focuses on the Cenozoic provenance and tectonic evolution of the southwestern Qaidam Basin through geochemical analysis of detrital garnet, tourmaline and rutile. The variation of detrital mineral compositions indicates that the Cenozoic evolution can be divided into three stages: (i) before the deposition of the upper Xiaganchaigou Formation (before 37.8 Ma); (ii) between the deposition of the upper Xiaganchaigou Formation and the Shangganchaigou Formation (from 37.8 to 22 Ma); (iii) since the deposition of the Xiayoushashan Formation (since 22 Ma). In the first stage, abundant garnets from high‐grade meta‐basic and ultramafic rocks in the sediments from the Ganchaigou area support a provenance from the South Altyn Tagh HP/UHP metamorphic zone. The low percentage of tourmalines from granitoid rocks in the sediments in the Kunbei‐Lücaotan area suggests a provenance from the East Kunlun fault zone, indicating that the Qimen Tagh Shan was not high enough to prevent the transport of sediments from the southern Qaidam Basin. The sediments in the Qigequan area were derived from both the Altyn Tagh fault zone and the East Kunlun fault zone. In the second stage, the tectonic activity consisted in the rapid uplift of the Altyn Shan. Changes in garnet composition indicate a lower detrital contribution from high‐grade metamorphic rocks. In the third stage, the disappearance of garnets from high‐grade metamorphic rocks and scattered temperatures of rutiles in the Ganchaigou area suggest that the source area shifted from the South Altyn Tagh HP/UHP metamorphic rocks to weakly metamorphosed Meso‐Neoproterozoic sedimentary rocks. The increase in granitoid‐derived tourmalines in the Kunbei‐Lücaotan area is indicative of the rapid uplift of the Qimen Tagh Shan. The provenance evolution in the southwestern Qaidam Basin indicates that the tectonic activity along the Altyn Tagh fault zone can be divided into an early stage of Altyn Shan uplift and a later stage of left‐lateral slip. At the same time, tectonic movement along the East Kunlun fault zone initiated. [ABSTRACT FROM AUTHOR]

As a traditional method for palaeoseismic studies, trenching can be combined with dating techniques to identify palaeoseismic events and the earthquake recurrence interval. However, when using trenches to study palaeoearthquakes, factors such as the active tectonic background of the earthquake‐caused structure, the lithology on both sides of the fault, the geomorphology location and type and the samples and methods for dating will affect the location of the trench. Thus, trenches should be carefully selected and used to identify the impact of ancient earthquakes. The results have substantial uncertainties and limitations. In recent years, scholars have made considerable progress in using other methods to reveal the palaeoseismic information of faults. Moreover, the history of fault activity may have been recorded in the lacustrine sediment adjacent to the fault. Hasuhai Lake is adjacent to the middle segment of the Daqingshan piedmont fault in Inner Mongolia. Since the Holocene, the region has experienced a temperate continental semi‐arid climate with little interference, and Hasuhai Lake and peripheral waters present weak hydrodynamic conditions that provide an ideal location for the study of palaeoseismic records in lacustrine sediments. Sediment samples and samples for dating were collected from three trenches excavated on the periphery of the Hasuhai Lake. Their variations in grain size and magnetic susceptibility revealed that wind and flowing water jointly produced the sedimentary conditions of Hasuhai sediments. The 14C dating results and variations in the grain size distribution, grain size components and magnetic susceptibility of sediments caused by seismic events obtained in this study were compared with those caused by a series of palaeoseismic events at the middle segment of the Daqingshan piedmont fault reported by previous studies using trenches, knickpoints and palaeosol records. The results identified seven palaeoseismic events recorded near Hasuhai Lake since 12,000 years. The combined use of lacustrine sediment variation characteristics and dating techniques is an effective method for studying palaeoseismic events. [ABSTRACT FROM AUTHOR]