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THE The Samarinda Anticline: Surface Field Study At Sungai Siring, Samarinda, East Kalimantan Dumex Pasaribu; Fikri Mustabidin; Epo Prasetya Kusumah
JURNAL TEKNOLOGIA Vol 3 No 2 (2021): Jurnal Teknologia
Publisher : Aliansi Perguruan Tinggi Badan Usaha Milik Negara (APERTI BUMN)

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Abstract

This research was conducted in the Sungai Siring area, Samarinda, East Kalimantan and geographically located at 117 ° 13'19.44 "- 117 ° 17'52.19" E and 0 ° 23'53.58 "- 0 ° 27'13.91" S with a research area of ​​about 50 km2. The aim of this paper is to report data from surface study and hoped that this data can provide additional data to explain the process the forming of Samarinda Anticline. The data used in this paper were obtained from lineament analysis on the Digital Elevation Model (DEM) data and the results of geological mapping in the Sungai Siring area including outcrop observations, measurement of stratigraphic section, and measurement of geological structure data. According to the result of this study, the formation of structure in the research area begins with the compression force with the main stress trending southeast (SE) - northwest (NW) which causes the formation of an thrust fault as a blind fault which then accommodates the layer above it to fold in the late Miocene age when the Sandstone - Claystone units and Coal insert Sandstone units was deposited. Geological section restoration was carried out using the line length method in four section, the results of the restoration in the study area generally had a shortening of 11% - 43% (843 - 2831 meters), contraction ratio are 0.57 - 0.89, strain are 0.11 - 0.43, and the depth to detachment are 3816 - 5984 meters. The greater of the shortening causes the depth to detachment to be shallower and the folds that are formed are tighter than the smaller shortening. Keywords: Sungai Siring, Samarinda Anticline, Restoration
Linear Regression for Flooding Surface Identification in Well Log, and Outcrop Image Epo Prasetya Kusumah; Ridha Santika Riadi; Teguh Surino Setiawan
Bulletin of Geology Vol 6 No 2 (2022): Bulletin of Geology Special Issue: International Seminar on Earth Sciences and Te
Publisher : Fakultas Ilmu dan Teknologi Kebumian (FITB), Institut Teknologi Bandung (ITB)

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Defining parasequences manually would take a huge amount of time. Interpretation subjectivity has also become an issue among stratigrapher when they are dealing with parasequence boundary identification which may resulting in inconsistency of parasequence identification. This paper means to present the use of automation in parasequence boundary identification using simple linear regression method in synthetic data, well log data, as well as outcrop image data. In stratigraphy, vertical succession of lithology holds a very important meaning. Vertical succession of lithology in paralic setting where deposition occurred in a certain sea level might shows coarsening upward vertical succession. In the event where flooding occurred and sea level abruptly rise, the coarsening vertical succession might be disturbed by sharp change of lithology into finer particle, or simply called vertical discontinuity. Stratigaphers may use vertical discontinuity to identify the presence of flooding surfaces or parasequence boundaries. Linear regression can be used to identify vertical discontinuity by measuring error occurred due to linear regression prediction. Vertical succession that showing deposition continuity might show small error number in the data where vertical disturbance occurred. The error value might increase significantly. Thus, it would be possible to determine flooding surface using linear regression by applying some threshold. This method has been proven to work using both well log data and outcrop image data which might ease stratigraphy analysis workflow in general.