The Optically Stimulated Luminescence dating of centennial-millennial paleoseismic events along the middle section of the Altyn Tagh fault, China.

Paleoseismology can evaluate past earthquakes ranging in time scale from centennial to tens of thousands of years. Characterization and dating of large prehistorical earthquakes further compensate for the incomplete historical and instrumental fault history [1,2]. The middle section of the Altyn Tagh fault (ATF) is an ideal nature place to conduct paleo-earthquake studies, because of its well-preserved evidence and clear fault track on the surface [3,4,5]. Radiocarbon dating is most routinely used in establishing the chronology of paleo-seismic events. However, materials with organic matter measured by using radiocarbon dating are not always available and are not directly associated with past earthquake-related deposits. For instance, organic matter is often scarce in arid and semi-arid regions of northwest Chinese. Optically stimulated luminescence (OSL) dating is an alternative technique to radiocarbon dating for providing the timing of paleo-earthquakes [4,6]. The sediments in the excavated trenches were usually deposited since the Holocene. Thus, to better constrain the timing of young earthquakes (for example ages (<5 ka), the accuracy and precision at the centennial and millennial-scale of the OSL dating need to be improved [7]. In this work, we choose the Copper Mine trenches along the Xorkoli section of the central ATF as a case to carry out the OSL dating of the paleo-seismic events [5]. Because the published 14C dating ages can provide an independent age control. Therefore, we collected the OSL samples to provide the timing of the young earthquakes. The OSL characteristics of quartz and K-feldspar grains, such as bleachability, OSL signal sensitivity, signal stability, etc., will be investigated. The suitable protocols for quartz and K-feldspar grains will be constructed, respectively. The reliability of young quartz and Kfeldspar ages will be corrected by the 14C ages. Finally, a reliable procedure can be established for yielding the centennial and millennial-scale ages. This work can provide an auxiliary dating method of paleo-earthquakes not only for the ATF but for western China. [ABSTRACT FROM AUTHOR]