Open AccessFacies and Architectural Element Analysis of Braided Fluvial Succession: The Tertiary Sawah tambang Sandstone, Sawahlunto, Indonesia
Author(s) -
Ugi Kurnia Gusti,
Budhi Kuswan Susilo
Publication year - 2019
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1363/1/012035
Subject(s) - geology , facies , outcrop , fluvial , overbank , geomorphology , structural basin , geochemistry
The Sawahtambang Sandstone Formation of Sawahlunto, Indonesia has hitherto never been studied in detail to ascertain its depositional processes and its palaeoenvironment. The Sawahtambang Sandstone has more than 394 m thickness which consists of conglomeratic sandstone, sandstone, and clay-silt intercalation within which six lithofacies types (St, Sp, Sh, Ss, Fl, and Fm) appear creating iterated fining upward sequence. Herewith, this paper aims to replenish the avantgarde sedimentological interpretation of the Sawahtambang Sandstone in the intermontane basin of Indonesia based on outcrops along the Trans-Sumatra Highway. The study is attained through facies identification based on stratigraphic measuring section or outcrop profile, studio analysis consists of log analysis and superposition reconstruction, and architectural element delineation according to facies association. Structures in clay-silt facies consist of lamination and fissile whereas in the sand grained include planar and trough cross-bedding, planar lamination and granule lag, which depicts a lower-flow-regime sand channel. The architectural elements that made from facies association are identified into five distinct elements (multi-storey channel, single storey channels, sand bedforms, laminated sand sheet, and floodplain fines), which present a fluvial environment. The relation of the architectural elements demonstrates that the Sawahtambang Sandstone uphold a record of the braided river system that flowed from southwest to northeast in the southwestern part of Ombilin Basin. The dominance of coarse-grained (channel and sandy bedform) element over clay-silt grained (laminated sand sheet and floodplain fines) element and the extensive appearance of thick amalgamated channel elements reinforce the interpretation of a low-sinuous braided fluvial system in which the stacking pattern shows the channel bodies accumulated both lateral via lateral accretion of point bar and via vertical amalgamated streams.