Ice-volume-forced erosion of the Chinese Loess Plateau global Quaternary stratotype site

T Stevens,J.-P Buylaert,A S Murray,H Lu,C Thiel,M Frechen,S Yi,G Újvári

doi:10.1038/s41467-018-03329-2

Abstract

The International Commission on Stratigraphy (ICS) utilises benchmark chronostratigraphies to divide geologic time. The reliability of these records is fundamental to understand past global change. Here we use the most detailed luminescence dating age model yet published to show that the ICS chronology for the Quaternary terrestrial type section at Jingbian, desert marginal Chinese Loess Plateau, is inaccurate. There are large hiatuses and depositional changes expressed across a dynamic gully landform at the site, which demonstrates rapid environmental shifts at the East Asian desert margin. We propose a new independent age model and reconstruct monsoon climate and desert expansion/contraction for the last ~250 ka. Our record demonstrates the dominant influence of ice volume on desert expansion, dust dynamics and sediment preservation, and further shows that East Asian Summer Monsoon (EASM) variation closely matches that of ice volume, but lags insolation by ~5 ka. These observations show that the EASM at the monsoon margin does not respond directly to precessional forcing.

Highlights

The International Commission on Stratigraphy (ICS) utilises benchmark chronostratigraphies to divide geologic time
In addition to recording East Asian Monsoon climate and Asian aeolian dust dynamics in loess and palaeosol units, the area records expansion and contraction of a desert sand sea that has experienced significant Holocene and recent desertification[7,8,9]. This is of particular relevance, given that the loess–palaeosol climate proxy record from the Chinese Loess Plateau (CLP) desert marginal Jingbian site (Fig. 1) has been adopted as the terrestrial stratotype for the International Commission on Stratigraphy (ICS) global benchmark Quaternary chronostratigraphic scheme[10, 11], plotted on the orbitally tuned CHILOPARTS time series[12]
Two palaeosols associated with the two ice volume minima of MIS 7 are preserved, separated by a loess unit representing the deep stadial during MIS 7, while MIS 5 and 1, which have no such deep stadials, are only represented as palaeosols at Jingbian. Based on this pattern and its relationship to the δ18O record, we propose an explanation of the mechanisms behind desert marginal sediment accumulation, preservation and erosion, and the controls on desert dynamics

Summary

Introduction

The International Commission on Stratigraphy (ICS) utilises benchmark chronostratigraphies to divide geologic time. We develop a fully independent age model for the Jingbian section over the last ~250 ka using a combination of the quartz OSL and K-feldspar post-IR Infra-Red Stimulated Luminescence (IRSL) techniques[19, 20] applied at high sampling resolution.

Results

Conclusion