Precise Thermoluminescence Dating for Heat Source Volcanic Rocks and Alteration Products at the Tawau Geothermal Area, Sabah, Malaysia

Abstract

The Quaternary eruptions are proved by two age data of 27000yBP by 14C and 1.62Ma by K-Ar methods. However, age data is not enough to prove Quaternary volcanic activity. New age data of Quaternary volcanic rocks are obtained for 12 samples by thermoluminecence (TL) method. The youngest age obtained is 0.09Ma for a monogenetic basaltic cinder cone. Ages such young basaltic volcanos are 0.10Ma and 0.11Ma (same outcrop) and 0.14Ma. Ages of dacitic volcanic rocks are widely distributed at the southern foot of the Maria volcano rage from 0.34Ma to 0.45Ma (4 samples). The ages of the underlying andesite lava range form 0.27Ma to 0.52Ma (4 samples). We obtained the preliminary age of 0.7-1.2Ma for this andesite lava formation by the correction of diagenesis. The relation between such age data and stratigraphical succession is still unknown, although new age data clarified the existence of volcanic activity in the Middle Pleistocene. Alteration ages of 13 samples are also measured by the TL method. The youngest ages obtained are 0.15Ma and 0.19Ma for Upper Tawau hot spring area. Other ages are widely scatted from 0.27Ma to 0.66Ma. They were used for the construction of the thermal history of each area. Alteration minerals are identified for 9 locations. The Tawau area is roughly estimated to be in the Middle Pleistocene by the TL age data.