Textural Characteristics and Depositional Environment of Ngrayong Sandstone (Middle Miocene) from Rembang Area, Northeast Java, Indonesia

Abstract

Granulometric analysis of Ngrayong sandstone samples from Rembang area of NE Java (Indonesia) has been carried out to examine the textural characteristics and elucidate depositional environment. The result data from the grain size analysis indicates that the Ngrayong sediments are classified as sand or muddy sands. They are very fine-to medium-grained (phi values: 1.67 to 3.35), moderately-to well-sorted (standard deviation: 0.19 to 0.57), strongly fineskewed to strongly coarse-skewed (skewness values: 4.82 to −5.97), and very platykurtic to very leptokurtic (kurtosis values: 0.36 to 2.41). Sandstone samples show unimodal grain size distribution. The sediments are interpreted to be transported in all three modes-traction, saltation and suspension, however, suspension and rolling are the major processes during transportation. Discriminant functions indicate diversity in the depositional environment for the sandstones. However, shallow marine is regarded as the dominant depositional environment. The preponderance of fine-grained sediments and lack of coarse sands suggest low to moderate energy conditions during deposition of Ngrayong sediments.

Distribution of Heavy Metals in the Sediments of Ganga River Basin: Source Identification and Risk Assessment

“…The range of grain size mean was 1.22 -6.51, which indicates medium-grained sands to medium-grained silt. Standard deviation (sorting) is found in the range of 0.59 -2.25 indicating very wellsorted to poorly sorted sediments which indicates that there were variations in the energy of the depositing medium during the deposition of these sediments (Blott & Pye, 2001, Khaing et al, 2022. Most of the samples were found poorly sorted(1-2phi), probably due to their various sources i.e.…”

“…mean, skewness, standard deviation, and kurtosis are summarised in (Supplementary Table 1). These attributes help to find the river energy conditions, the size of the grains, the role of depositional medium in the separation of grains Disastrous risk of different classes, and its flow characteristics (Folk, 1974;Baruah et al 1997;Eisema, 1981;Blott & Pye, 2001;Khaing et al, 2022;Ray et al, 2006). The range of grain size mean was 1.22 -6.51, which indicates medium-grained sands to medium-grained silt.…”

“…52% of sediment samples have finer sand and silt particles. Kurtosis ranges from 0.8 -2.64, suggesting platykurtic to very leptokurtic samples and indicating that fluctuations occurred in the flow features of the deposition medium at the time of sediment deposition (Khaing et al, 2022). The presence of minute clay indicated low chemical weathering in the source region (Singh., 2009).…”