Abstract
The research area is located in Miri region, north Sarawak. Observation was focused on selected outcrops along road cuts and beach. The distribution of outcrops is widely distributed at a few localities in Miri region such as Tanjong Lobang, Airport road, Hospital road and Oil Well road. Sedimentary sequences can be traced by facies variations as shoreline environment based on the sedimentary structures. Four facies were identified and characterised successfully in the study area based on their sedimentary structures, namely facies 1: planar cross stratified (PcS), facies 2: swaley cross stratified (ScS), facies 3: swaley-Hummocky cross stratified (SHcS), facies 4: Hummocky cross stratified (HcS) and heterollithic facies (He). Facies evaluation deduced that the sedimentation settings resulted as foreshore, upper shoreface, middle shoreface, lower shoreface and tidal (minor occurrence). Wave-dominated in the upward coarsening interval is unambiguous that representing by abundance of hummocky cross stratification and other storm deposits in the sandstone dominated portions, well-defined swaley cross stratified sandstone interval, and up to several meters thick sets of planar cross beds interval interpreted to have been formed by swash waves. Heterolithic units in this wave dominated sequences are as minor occurrence of tidal influence during fair weather .
Highlights
The study area is enclosed by longitudes between the 113o20’ E to 114o20' E and between the latitudes of 4o16' N to 4o24’ N (Figure 1)
Five facies are identified on outcrop of the Miri Formation which is divided into major facies and minor facies
Based on the vertical litholog constructed from the outcrop at airport road, stacked sandstone bed with planar cross stratified is about 32 meters height (Figure 3)
Summary
The study area is enclosed by longitudes between the 113o20’ E to 114o20' E and between the latitudes of 4o16' N to 4o24’ N (Figure 1). The study area is largely consists of sandstone and mudstone interbeds This formation can be traced by facies variation as foreshore to shoreface environments. Observation started at the Canada Hills in Miri town which was one of the main places established for oil exploration and drilling in 1910 to 1971 and stretches along the Miri Hospital road, Oil Well road and Airport roads [1]. These places exposed the well preserved outcrops of Miri Formation rock unit and be a good section for litholog measurements. This research hopes to add on some knowledge about basic sedimentology in Miri Region and give simple guide to young researchers to understand wave dominated sequence in the field
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