Bulletin of the Geological Society of Malaysia, Volume 70, November 2020, pp. 139 – 151
Norhanizan Zaini1,*, Antonino Briguglio2, Sulia Goeting2, Amajida Roslim1, László Kocsis1
1Geology Group, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong, BE1410, Brunei Darussalam
2DI.S.T.A.V. – Dipartimento di Scienze della Terra, dell’Ambiente e della Vita, Università degli Studi di Genova, Italy
* Corresponding author email address: norhanizan.zaini@gmail.com
Abstract: The study aims to get some additional knowledge on the modern seafloor composition offshore Brunei Darussalam by looking at the recent stratigraphic succession of the deposited sediments and their distribution patterns. For this reason, 10 shallow cores (22 to 46 cm thick) have been collected by scuba diving along two depth transects spanning from water depth of 20 to 60 m. One of the transects has been sampled north-northwest of the Muara village, just in front of the Brunei Bay and the other one off the coast near Tutong town, away from major sedimentary inputs. The results obtained portray two different sea bottom compositions and two different depth-related sediment distributions. The Muara transect is highly rich in mud and yielded abundant biogenic component at all investigated depths. The Tutong transect has a higher sand content but display constant changes along with depth. The sediment is mostly composed by biogenic grains such as rests of sponges, foraminifera, molluscs and echinoderms; the not biogenic grains are for the vast majority made of quartz. The sandy fractions of both transects have been tested for cyclicity and all cores can be described by functions with comparable periods, thus indicating that an oscillatory environmental event such as the alternation of the monsoon seasons, has similar influence on the seafloor of both transects.
Keywords: Sedimentology, biogenic component, depth distribution, offshore Brunei, marine environment
DOI: https://doi.org/10.7186/bgsm70202012
