Warta Geologi, Vol. 46, No. 2, August 2020, pp. 45-51

The characteristics and morphology of columnar dacite in Tawau, Sabah

Elvaene James, Hennie Fitria W. Soehady Erfen, Azman A. Ghani, Angela Vidda Chuwat, Gerald Eko Ejiga

¹Dept. of Geoscience, Faculty of Earth Science, University Malaysia Kelantan, 17600 Jeli, Kelantan, Malaysia

²Department of Geology, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia

³Faculty of Science & Natural Resources, University Malaysia Sabah, 88400 Kota Kinabalu, Sabah, Malaysia

⁴School of Physics, University Sains Malaysia, 11800 Penang, Malaysia

* Corresponding author, e-mail: Elvaene_anne@yahoo.com

Abstract: The occurrence of columnar jointing is commonly associated with volcanic rocks and a rapid cooling environment. We recently discovered well-preserved columnar dacite on the road cutting slope in the eastern part of Tawau town, Sabah. This paper briefly describes the occurrences and morphology of columnar dacite in the study area. Columnar dacite exhibits entablature feature since it has thinner and chaotic columns. The hexagon side dominates the columnar joints with minor pentagons to heptagon sides. Columns for dacite are much smaller compared with columnar basalt Tawau. The formation of columnar joints was influenced mainly by external fluid where the water flow on top of the cooling lavas makes it cool rapidly.

Keywords: columnar dacite, entablature, Tawau, rapid cooling

DOI :
https://doi.org/10.7186/wg462202002

SSN
0126–5539; e-ISSN 2682-7549