The Determination of Sedimentation Rates Using 230th and 230thexcess Methods in Kuantan Mangrove Forest, Malaysia

B. Y. Kamaruzzaman, H. Mohd. Lokman, I. Sulong, A. S. Johanna and C. C. Khoo

Mangrove Research Unit (MARU), Institute of Oceanography, Kolej Universiti Sains and Teknologi Malaysia, 21030 Kuala Terengganu, Terengganu, (Malaysia)

To explore the sedimentation process in the mangrove forests, two sediment cores from the Kuantan mangrove forest, Malaysia were studied by measuring the element thorium (Th). A 230Thexcess (non-supported 230Th in sediments) and 230Thexcess/232Th methods were used to determine the sedimentation process where a sediment up to 300,000 years old can be dated. Applying the 230Thexcess and 230Thexcess /232Th methods, average sedimentation rates for both cores and for the both methods are 0.62 cmyr -1 were obtained. The fairly high average sedimentation rates obtained indicating that the mangrove forests may still be prograding and in an immature stage. If the sedimentation rates are applicable to the core samples, the mangrove forests of Kuantan mangrove forest is probably in an immature stage with an estimated age of about 161 years. This finding also suggests that the mangrove forests are not just passive colonizers of mud banks, but actively capture mud to create their own environments.

Sedimentation rates; 230Th and 230Thexcess