Dating Holocene lake sediment core using paleomagnetic secular variation at Guozha Co, the northwestern Tibetan Plateau

Because of the reservoir effect in the lake sediments, especially the glacier-fed lake systems, it is difficult to establish the reliable chronological controls using ¹⁴C techniques on the Tibetan Plateau. The study of the paleomagnetic secular variation (PSV) and relative paleointensity (RPI) could provide references for the establishment of chronological controls during the Holocene. In this study, we attempt to apply the paleomagnetic inclination record to establish chronological controls for the sediment core, GZHC-2014-1, at Guozha Co, the northwestern Tibetan Plateau. Guozha Co is mainly recharged by glacial melt water from Guliya glacier in the west Kunlun Mountain. The magnetic minerals in GZHC-2014-1 are mainly composed of the pseudo single domain magnetite, and maintain a relatively good primary sedimentary state, suggesting the core is suitable for establishing the PSV and RPI records. We constructed a paleomagnetic inclination-depth model. Comparing with the PSV stack for East Asia, Lake Tangra Yumco (in the central Tibetan Plateau), as well as with geomagnetic field models, we have defined 11 reference pinpoints of the PSV in the Holocene, which is supported by regional RPI variation. The ¹⁴C reservoir ages varied between 7500 and 11500 by comparing the PSV dating and ¹⁴C dating on bulk organic matter. Variations of the reservoir ages appear to be related with the contents of magnetic minerals in the sediments. This study provides robust chronological controls for the sediment core at Guozha Co, which is helpful for further investigation of climate changes in the northwestern Tibetan Plateau.