Mineral magnetic study of lacustrine sediments from Lake Pumoyum Co, southern Tibet, over the last 19 ka and paleoenvironmental significance

High-resolution proxy records from Tibetan Plateau are essential to understand the past climatic and environmental changes. In this work, we conducted systematic environmental magnetic studies on lacustrine sediments from Lake Pumoyum Co, southern Tibet, spanning from the last deglaciation (similar to 19 ka) to present. We correlated the magnetic proxies in the lake core with environmental changes. The magnetic proxies from the 3 units were studied. Both Unit 3 (19-13.2 ka) and Unit 2 (13.2-8.4 Ica) contain evidences for an anoxic or sub-anoxic environment. Fine-grained greigite dominates the bulk magnetic properties of Unit 3, while both magnetite and greigite coexist in Unit 2. Overall, this reveals a transition from an anoxic environment to an oxic environment. In contrast, Unit 1 (8.4 ka-present) spans the Holocene when the lake environment was oxic. There is an increasing trend in the concentration of magnetic minerals, which reflects an increasing transport of magnetic minerals from the catchment into the lake due to the increased post-glacial melt-water flow. Although different mechanisms affect the magnetic assemblage and associated magnetic properties in the different units, our results suggest that the magnetic proxies of the local lake environment on southern Tibet are sensitive to environmental changes. (C) 2012 Elsevier B.V. All rights reserved.