The patchwork loess of Central Asia: Implications for interpreting aeolian dynamics and past climate circulation in piedmont regions

ABSTRACTReconstruction of mass accumulation rates (MARs) in loess deposits are widely used for interpreting long‐term aeolian transport and climate dynamics in terrestrial environments. However, these interpretations are often driven by a preponderance of reconstructions from individual or selected sites, which can bias our understanding of past climate, especially in the absence of other proxy information. Recent studies on MARs from multiple loess sites in Arid Central Asia (ACA) reveal disparities in the timing of peaks in accumulation between sites, as well as asynchronies with loess flux in the Chinese Loess Plateau (CLP). We investigate this issue by (1) dating five new sites from the western Ili Basin, therefore extending the spatial cover of loess chronologies across ACA and (2) combining that with MARs from >30 sites across ACA and the CLP over the last 60 ka. Our results indicate spatio‐temporal inhomogeneity in the timing and rate of loess deposition across the ACA, and highlight the importance of interrogating local and regional influences on dust supply and transport. Our synthesis of MARs from ACA and the CLP suggests that the timing of peak dust flux as an indicator of large‐scale climate dynamics is best derived from an aggregate of sites; this removes site‐specific bias where local processes or topographic settings outweigh the climate signature.L Lisá acknowledges the support of internal program No. RVO67985831 of the Institute of Geology CAS, Prague and OP RDE, MEYS under the project ‘Ultra‐trace isotope research in social and environmental studies using accelerator mass spectrometry’, Reg. No. CZ.02.1.01/0.0/0.0/16_019/0000728.This study was funded by an independent Max Planck Research Group awarded by the Max Planck Society to KE Fitzsimmons

Reevaluation of Late Pleistocene loess profiles at Remizovka (Kazakhstan) indicates the significance of topography in evaluating terrestrial paleoclimate records

We report on a loess-paleosol sequence (LPS) near Remizovka, located in the northern Tian Shan piedmont of southeastern Kazakhstan. This site represents a key record for Late Pleistocene climatic fluctuations at the intersection of major northern hemisphere climate subsystems. This paper develops a synthesized dataset of previous conflicting studies at Remizovka by characterizing their (paleo)topographic context, which had remained previously overlooked. Digital elevation models, satellite images, and archival photography characterize recent topographic developments. Two well-developed pedocomplexes, which we investigate in detail and date by luminescence mark the paleotopography during Marine Oxygen Isotope Stage (MIS) 5. Peak dust accumulation rates here occurred during the middle MIS 5 and MIS 4/early MIS 3. These are partially comparable with records from neighboring regions, but not in phase with global ice volume records. This discrepancy may be related to a distinct regional environmental response to larger-scale climatic drivers and local topographic influences on dust deposition patterns. Our findings confirm the potential of the LPS Remizovka to provide high-resolution paleoclimate data for the Late Pleistocene. The three-dimensional stratigraphic reconstruction reinforces the caution required to correctly interpret loess formation processes prior to their interpretation as paleoclimate archives, and provides guidelines for a more suitable approach

A Novel Proxy for Tracking the Provenance of Dust Based on Paired E_1'-Peroxy Paramagnetic Defect Centers in Fine-Grained Quartz

Crystal lattice defects in quartz have long been exploited for age determination, yet also show potential for sediment provenance studies. Here, we introduce a novel method for tracking aeolian dust provenance by utilizing the natural accumulation of E1’ and peroxy defect centers in quartz. Our approach is based on the previously observed premise that E1’ and peroxy centers arise from Frenkel defect pairs, and that their concentration increases with the age of the quartz-bearing source rock. We propose that these defect centers can be utilized as a characteristic feature of the source rock and consequently, for fingerprinting sediments derived from it. We successfully apply our new protocol to distinguish fine-grained quartz extracted from loess deposits from two regions in Central Asia which are known to derive from different source material of differing age. Our method offers strong potential for identifying variability in source, both spatially and through time down sedimentary sequences