Paleoclimatic Registers from Semi-arid Costal Sediments of Southeastern India: A Multi Proxy Approach

Abstract

The red sand dunes appear along the south east, -west coast of Tamil Nadu, India between the latitudes and longitudes of 8°07′56″N to 8°22′11″N; 77°19′84″E to 77°53′40″E. The dune sands from this region were studied through magnetic methods such as magnetic susceptibility measurements and acquisition of isothermal remanent magnetization, geochemistry and X-ray diffraction methods. Optically stimulated luminescence (OSL) dating method was used to constrain the chronology of deposits. Three sections were excavated up to 5–9.5 m with one inland deposit (TPV) and two near coastal sections (THOP and MUT). The magnetic parameters show both significant contribution of hematite structures and indicate the presence of multi-domain magnetite or mixed mineral contents of magnetite and anti-ferromagnetic minerals in the sample. The occurrence of magnetite in THOP and TPV sections is possibly due to the marine sediments transported by sturdy onshore winds. In XRD data, correlation analysis indicated TPV and MUT sections have a similar type of deposition and THOP did not show any positive correlation with TPV and MUT and even with its own deposition. In comparison with geochemistry data, χ variation and OSL dates, it was shown that the sample MUT21 (200 cm) with an OSL age of 14 ± 2 ka indicated deposition during the humid interval and at ~17 ± 2 to ~19 ± 2 ka MUT61 (600 cm)depicts the dry period of deposition.