Terminal Pleistocene/Holocene palaeoenvironmental changes revealed by mineral-magnetism measurements of lake sediments for Dali Nor area, southeastern Inner Mongolia Plateau, China

Mineral magnetic properties (SIRM, ARM, HIRM and S-ratios) are presented for two AMS 14C-dated pit-sequences of lake sediments recovered from Haoluku and Liuzhouwan (∼43°N, 117°E). The two sites fall in the semi-humid to semi-arid climate transition zone, Dali Nor area of the southeast Inner Mongolia Plateau, China. Complemented by data for loss-on-ignition (LOI), total organic carbon (TOC), carbon/nitrogen (C/N), grain-size, and pollen, these mineral-magnetic measurements provide additional insights into environmental changes occurring at this area over the last 13 500 years. Conditions were extremely dry and windy as shown by the low SIRM, ARM and HIRM and high S-ratios before 13 500 yr bp. The environment began to ameliorate gradually since then, and a further humidification occurred at ∼10 300 yr bp in Haoluku, the northern site, and at ∼9400 yr bp in Liuzhouwan, the southern one, as implied by the increased but only moderately high SIRM, ARM and HIRM and decreased S-ratios. As indicated by the remarkably increased SIRM, ARM, HIRM and S-ratios, a deterioration commenced at ∼5600 yr bp in Haoluku and at ∼4700 yr bp in Liuzhouwan. In Haoluku, conditions have been generally dry and windy since ∼5600 yr bp despite a minor amelioration at 4500–3000 yr bp. A short but marked amelioration occurred at 1200–700 yr bp in Liuzhouwan. S-ratios seem to be a reliable indicator of environmental aridity for this area.