Quartz and K-feldspar luminescence dating of a Marine Isotope Stage 5 megalake in the Juyanze Basin, central Gobi Desert, China

The Juyanze Basin, in the central Gobi Desert of China, contains one of three terminal lakes of the Heihe River, the second largest inland river in China. The paleoenvironmental record of the region is important since it is a significant global dust source region. In this study, a newly developed post-infrared(IR)-stimulated luminescence (IRSL) (pIRIR) dating technique, together with traditional quartz optically stimulated luminescence (OSL) dating, was applied to shoreline and deep water sediments obtained from a buried shoreline at ~ 927 m in the Ejina Basin, ~ 33 m above the basin floor. The reliability of K-feldspar pIRIR dating was confirmed by internal checks of a dose recovery test, an anomalous fading test, and a residual dose test. Internal checks of the quartz OSL dating, and comparison to K-feldspar pIRIR ages, indicate that the single-aliquot regenerative-dose protocol was reliable for samples from the shoreline, but that quartz ages older than 60 ka may be underestimated. Our results indicate that three lacustrine sequences, separated by erosional unconformities and eolian deposition, span a period from ~ 122 to 73 ka, covering most of Marine Isotope Stage (MIS) 5. At a depth of ~ 33 m (~ 927 m elevation), the paleolake covered more than 1800 km2 in the Juyanze Basin during this period but fluctuated frequently. Whether or not this MIS 5 lake filled the entire Ejina Basin or merely overflowed the Juyanze Basin to partially fill the other Ejina sub-basins remains unknown. Regardless, the presence of such a large MIS 5 paleolake in the Ejina Basin suggests its lake history closely matches those from other closed-basin drainages originating in the Qilian Mountains. We suggest that the high stands appearing during MIS 5 in the Juyanze Basin likely were a response to moist climatic conditions during the last interglacial period.