HIRM variation in the Ganzi loess of the eastern Tibetan Plateau since the last interglacial period and its paleotemperature implications for the source region

Reconstruction of paleotemperatures in loess sequences plays a crucial role in paleoclimate research. Depositional-origin hematite is considered a major contributor to high-field isothermal remanence (HIRM), which is closely related to temperature. However, there is limited knowledge regarding hematite of various origins that contributes to the HIRM in Tibetan Plateau (TP) loess deposits. Here, the variation in and contributions of hematites of various origins to HIRM in the Ganzi loess of the eastern Tibetan Plateau (ETP) and their paleoclimatic significance are investigated in detail. We find that depositional hematite is the main contributor to HIRM in the ETP loess and HIRM can be used as an indicator of temperature variation on the TP. During the interglacial period, the TP dust source became more arid, which was conducive to production of more hematite. During the glacial period, the TP dust source region became colder and drier, which was not conducive to the formation of hematite. The HIRM record shows that the TP temperature has varied with orbital-scale glacial-interglacial changes since the last interglacial period. This was mainly in response to Northern Hemisphere summer insolation. The loess source region in the interior of the TP was warmest during the last interglacial period (MIS 5) and the Holocene. Its coldest period occurred during MIS 2. The climate was relatively mild during MIS 3. This study provides further understanding of environmental changes in the TP. (c) 2021 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.