A LUMINESCENCE METHOD FOR DATING DIRTY PEDOGENIC CARBONATES FOR PALEOENVIRONMENTAL RECONSTRUCTION

Pedogenic carbonates are sensitive paleoclimatic and paleomonsoonal in dicators, stratigraphic markers and important sources and sinks in the global CO budget. Establishing a chronology of such carbonates has be en difficult due to their open-system behaviour with respect to the ra dioisotopes used for dating, A luminescence method for chronometric da ting of carbonates is proposed which is less susceptible to post-depos itional changes and uses subtle changes in the radiation flux to a min eral grain on being carbonated. This change is estimated by measuring luminescence signals of carbonated and uncarbonated mineral separates from the sediment strata and can be related to the age of the carbonat e formation. Such ages of pedogenic carbonates from Thar Desert, India conform with paleoclimatic and stable isotopic data and show that the y formed in Thar ca. 17 ka, 5 ka and 2 ka ago, since the last glacial epoch.