A 2000 year geochemical record of palaeoclimate and hydrology derived from dune sand moisture

Abstract

Chloride concentrations in the interstitial water of the unsaturated zone in dune sands of the Badain Jaran desert, northwestern China have been used to examine the recharge history over the last 2000 years using a chloride mass balance approach. The estimated 0.9 mm yr − 1 recharge represents approximately 1% of annual precipitation in the western part of the desert and this low but finite infiltration allows preservation of this record. The 30 m deep profile yields a total archive equivalent to 2050 years with well-preserved climatic events of 30–50 years duration. Periods of relatively dry years occurred during AD 100–250, 350–600, 870–1220, 1330–1450, 1570–1720, 1780s and 1900–1970. The unsaturated zone profile provides a robust climate record with a resolution of +/− 20 yr comparable favourably to tree ring and ice core records in this region.