Geomorphological Characteristics of Phu Phra Angkhan, Buriram Province: Evidence from Remote Sensing and Geological Data

Nattarika Meesa — 2025-12-30

Phu Phra Angkhan, the small hill where the architectural and religious sites have been established, is in Buriram p, northwestern Thailand. The area has been selected for the current investigation with the aims of determining geomorphological characteristics and proposing the mode of occurrences using geographic information system (GIS). The current research commences from geological data compilation, remote-sensing image interpretation, field checking, and explanation of the landform. The result illustrates that Phu Phra Angkhan is a small extinct volcano, based upon the radiometric age (~ 0.9 Ma) of the volcanic rocks at the nearby Khao Phanom Rung volcano. The current field study demonstrates that Phu Phra Angkhan volcano consists of massive layers of alkali olivine basaltic lava without any pyroclastic debris. Previous geochemical data reveal that the silicon oxide is lower than 55 %, suggesting that the lava has low viscosity enough to spread over a wide area. The lava accumulation may have caused the cone - shaped volcanic landform forming shield or dish cover with relatively not gentle slopes. Additionally, it is also recognized that its crater has a circular shape with the radius of 1.0 to 1.5 km, and its circumference is about 3.14 km. The cross sections in several directions disclose that the Phu Phra Angkhan volcano has its various slope angles and asymmetrical shapes. The steeper slope angles are in the eastern flank with its deeply eroded slope surface whereas on the western flank more gentle slopes are encountered. Based on its morphology and landform characteristics and classification, it is concluded that Phu Pra Angkhan represents the extinct shield volcano with the collapsed crater, formed by explosion associated with surface subsidence. Its mode of occurrence is manifested by a complex crater forming as nested circumferences. Moreover, a very small mound or hill is found at the eastern edge crater, triggered by crater-ring fracturing, implying the last, relatively violent eruption. It is also anticipated that the temple located at the crater edge is considered to be safe from a landslide disaster.

Permian radiolarian cherts and their geochemical characteristics in the Central Plain of Thailand: Implications for the geological affiliation and origin of the Permian chert

Waraphorn Phromsuwan — 2025-12-30

Improved geological constraints refine our understanding of Southeast Asia's and Thailand's geotectonic evolution. This study investigates Permian chert successions in the Central Thailand, where are the Sawan Khalok and the Nakhon Sawan–Uthai Thani areas, to elucidate their genesis, depositional environment, and implications for the tectonic evolution. The Central Thailand is interpreted as part of the Sukhothai Zone characterized by an island arc setting such Permian-Triassic volcanic rocks, formed by the subduction of the Paleo-Tethys Ocean with the Indochina Block. Permian cherts, previously considered enigmatic, are irregularly distributed in this zone. The research examines four chert sections, identifying the Early Permian radiolarians (Asselian) in TS13, specifically Pseudoalbaillella simplex and Pseudo-albaillella cf. annulata, and late Early – early Middle Permian (Kungurian–Roadian) in TS14, comprising Albaillella sinuata and Albaillella cf. asymmetrica. The Middle Permian radiolarians (Roadian–Capitanian) identified include Pseudoalbaillella scalprata, Parafollicucullus fusiformis, Parafollicucullinoides cf. globosus, Parafollicucullus monacanthus, Follicucullus cf. scholasticus, and Follicucullus cf. bipartitus form NS07. For NS11, the identified radiolarians are Pseudoalbaillella cf. lomentaria, Pseudoalbaillella scalprata, Parafollicucullus monacanthus, and Follicucullus cf. scholasticus indicating Wordian–Capitanian ages.

Geochemical analyses (ICP-OES and ICP-MS) of chert samples from the four sections provide insights into their origin and depositional setting. Samples of TS13 and TS14 exhibit origins of hydrothermal influence and show a negative Ce anomaly, suggesting depositing nearby a spreading ridge environment with limited hydrothermal activity. Samples of NS07 and NS11 plot close to biogenic chert origin and display a depleted Ce anomaly, indicating decreased hydrothermal material input or deposition near a continental margin. Based on lithological characteristics and radiolarian ages, chert successions in the Sawan Khalok and the Nakhon Sawan–Uthai Thani areas are considered to have same origins of the Khanu Chert and the Khao Gob Chert. In terms of depositional time intervals and geochemistry characteristics, those of the cherts can correlate with cherts from the Sa Kaeo area, representing the Early and Middle Permian chert sequences, originated in a back-arc basin setting rather than formed in a vast oceanic setting of the Paleo-Tethys Ocean. This study confirms an existence evidence of a back-arc basin chert in the Central Thailand, extending the known distribution of the Sa Kaeo suture zone northwestward from the Uthai Thani and Nakhon Sawan areas into the Sawan Khalok area, and continues toward the Nan suture. These stratigraphic relationships can be explained by the fact that the bedded cherts were thrust onto the structurally higher rocks of the Sukhothai Zone, due to lateral shortening tectonics associated with the closure of the back-arc basin.

Thai Geoscience Journal

Geomorphological Characteristics of Phu Phra Angkhan, Buriram Province: Evidence from Remote Sensing and Geological Data

Permian radiolarian cherts and their geochemical characteristics in the Central Plain of Thailand: Implications for the geological affiliation and origin of the Permian chert