Laminated Sediment Archives from a Maar Lake in the Central Highlands, Vietnam, as a Recorder of Holocene Hydroclimatic Variability in the Monsoon

A significant portion of the global population is directly affected by variability in the Asian monsoon, yet knowledge of the temporal response of this system and related climatic phenomena (i.e. ITCZ, tropical cyclones and Walker Circulation) over extended time periods, such as the Holocene, is lacking. In addition, restricted site access in tropical mainland Southeast Asia has limited research on paleoclimate proxies leading to a deficit in these critical records. Central Vietnam's Pleiku volcanic field features numerous maar lakes and dry maars formed over 0.2 Ma ago that contain sediment archives of monsoon variability extending from the Pleistocene through the Holocene. The preliminary radiocarbon age model predicts that 6 m depth encompasses the past 12,000 years. Our preliminary data for one of these maar lakes, Biển Hồ near Pleiku (14° 03'03.5" N, 108° 00'00.2" E) suggest that the lake's laminated sediments are protected from bioturbation by suboxic bottom water ( 21 m depth). Paleolimnological changes can be evaluated using suites of source-specific biomarkers responsive to environmental changes in algal productivity (e.g., Botryococcus). In addition, compound-specific isotope analysis (CSIA) of terrestrial plant leaf waxes provides the ability to reconstruct past hydroclimatic variability at this site. Thus, a coupling of lacustrine and terrestrial biomarkers from these sedimentary archives facilitates evaluation of paleoenvironmental responses to changes in precipitation in the Central Highlands of Vietnam. The biogeochemical records from the lake demonstrate that they provide records of climate variability and yield insights into the climatic regime of a region where rainfall and droughts profoundly influence population dynamics and have the potential to create social and economic distress.