| Abstract |
In northern Taiwan, the Quaternary volcanoes consist of the Tatun and Chilung Volcano Groups, the Kuanyinshan Volcano and offshore volcanic islets, i.e., Chilungtao, Huapaingshu, Meinhuahsu, and Penghiahsu. These compositions of volcanic rocks are predominantly composed of andesite with a little basalt or dacite. The Tatun Volcano Group (TVG), a typical multivent volcano, containing at least twenty volcanic composites, cones and domes in an area of 20× 20 km2 (400 km2), occupies the most volcanic areas in northern Taiwan. The post volcanic activities of the TVG, i.e., hot springs and gas fumaroles, are well developed now and are mainly distributed in the periphery of main volcanic composites and cones along the Chihshan Fault with an area 18 × 3 km2 from the south to the north of the TVG area. The Longfengku and Liuhaungku are two of the most active post volcanic activities areas of the region. The weathering processes involve the precipitation, the most common aspect, and volcanic gases. The aim of this paper is to study the erodibility of individual element as the proxy for mineralogical facies transition under the influence of volcanic gases in the TVG. The preliminary results showed that it has no evident element been eroded with samples taken from brownish-covered weathered andesite. In contrast, it has a lot of elements been eroded away, such as alumina, iron, potassium, and calcium in white-covered weathered andesite. Silicon and titanium are the most stable and resistant elements in the process. |