# Shifting material source of Chinese loess since ~2.7 Ma reflected by Sr isotopic composition

## TL;DR

This study shows that the source of dust on the Chinese Loess Plateau shifted over millions of years, which has implications for understanding long-term climate changes.

## Contribution

The study identifies a gradual shift in dust sources from the Qilian to the Gobi Altay Mountains over the past 2.7 million years using Sr isotopic analysis.

## Key findings

- The source of eolian dust on the CLP remained unchanged on orbital timescales.
- A gradual shift in dust source from Qilian to Gobi Altay Mountains occurred over 2.7 million years.
- Tectonic uplift and climate changes, including winter monsoon intensification, influenced the dust source shift.

## Abstract

Deciphering the sources of eolian dust on the Chinese Loess Plateau (CLP) is fundamental to reconstruct paleo-wind patterns and paleo-environmental changes. Existing datasets show contradictory source evolutions of eolian dust on the CLP, both on orbital and tectonic timescales. Here, the silicate Sr and Nd isotopic compositions of a restricted grain size fraction (28–45 μm) were measured to trace the source evolution of the CLP since ~2.7 Ma. Our results revealed an unchanged source on orbital timescales but a gradual source shift from the Qilian Mountains to the Gobi Altay Mountains during the past 2.7 Ma. Both tectonic uplift and climate change may have played important roles for this shift. The later uplift of the Gobi Altay Mountains relative to the Qilian Mountains since 5 ± 3 Ma might be responsible for the increasing contribution of Gobi materials to the source deserts in Alxa arid lands. Enhanced winter monsoon may also facilitate transportation of Gobi materials from the Alxa arid lands to the CLP. The shifting source of Asian dust was also reflected in north Pacific sediments. The finding of this shifting source calls for caution when interpreting the long-term climate changes based on the source-sensitive proxies of the eolian deposits.