Bulletin of Earth Sciences of Thailand

Mineral chemistry and petrography of granitic rocks related rare earth elements in Uthai Thani area, central Thailand: Implication for REE potential in Thailand

Panawat Watthanapond, Tawachai Chualaowanich, Alongkot Fanka — Tue, 31 Dec 2024 00:00:00 +0700

Granitic rock, one of the rare earth elements (REEs) sources, exposes in several areas in Thailand including Uthai Thani, Central Thailand. Biotite-muscovite granite can be found in Uthai Thani area, Central Thailand. The biotite-muscovite granites show porphyritic texture with K-feldspar megacryst and foliated texture in some locations, with mineral compositions of quratz, K-fledspar, plagioclase, biotite and muscovite with accessory minerals of opaque minerals, apatite, zircon, monazite, and ilmenite. This granite can be classified as Ilmenite series or S-type granite. The primary REE minerals associated with this granite are mainly monazite, xenotime, and ilmenite. The mineral chemistry indicates that these REE-bearing minerals can be potential LREE (Ce, La, Pr, and Nd) sources and some HREE (Y, Gd, Dy) sources.

Petroleum system modeling in the Songkhla basin, Gulf of Thailand

Kanyapat Tongsanthia, Piyaphong Chenrai — Tue, 31 Dec 2024 00:00:00 +0700

The Songkhla Basin in the southwestern Gulf of Thailand, notable for hydrocarbon exploration, contains petroleum source rocks in Early Oligocene strata. This study constructed a one-dimensional petroleum system model based on well data and seismic data. Findings show that the source rocks began hydrocarbon generation in the Early Miocene, reaching significant transformation in the Middle Miocene, and continuing to the present day. Seismic data suggest that fault activity likely caused oil leakage, impacting current exploration viability. This research provides insights into the maturation history and potential for future hydrocarbon exploration in the Songkhla Basin.

Petrochemistry of volcanic rocks in Suwan-N Prospect of Chatree gold deposit, Phichit Province, Central Thailand

Tue, 31 Dec 2024 00:00:00 +0700

Suwan-N prospect is in Phichit Province, Central Thailand, within the Loei Fold Belt, a region known for its significant mineral deposits, including the nearby Chatree gold deposit. This study focused on the lithology and geochemistry of volcanic host rocks and an associated andesitic dyke collected from the Suwan-N prospect. Main volcanic hosts were identified as plagioclase-hornblende-phyric andesite, plagioclase-phyric dacite, and andesitic breccia. In addition, an andesitic dyke was described as a later state that intruded into the earlier host volcanics. Petrographic features and geochemical compositions indicated that these host volcanic share similarities with other epithermal deposits in the Loei-Phetchabun-Nakhon Nayok volcanic belt, displaying calc-alkaline magmatism and pervasive hydrothermal alteration. In contrast, the later andesitic dyke exhibited a distinct tholeiitic magma series, suggesting it originated from a different magmatic process. Geochemical data suggested that this andesitic dyke intruded after the main mineralization phase, pointing to the continuation of tectonic activity in the region.

Optimizing CO2 Truck Transport Routes from Sources to Storage in Northeastern Thailand

Passawan Chaisurajinda — Tue, 31 Dec 2024 00:00:00 +0700

The rise in CO₂ emissions has paralleled the country's economic growth, with the energy sector being the primary source. In northeastern Thailand, power generation, particularly from biogas-based plants, contributes significantly to these emissions. To effectively mitigate CO₂ emissions by capturing and transporting CO₂ from emission sources to the storage site of the Nam Phong power plant for the implementation of carbon capture and storage (CCS) technologies in a depleted gas field, the assessment of logistics is required. This study determines optimal truck transportation routes for 23 CO₂emission point sources in northeastern Thailand, providing comprehensive details such as starting and ending points, working hours, pickup quantities, total distance traveled, and cost per trip. The analysis identifies an optimal solution utilizing seven vehicles to efficiently collect CO₂ emissions from all designated locations, with daily CO₂ emissions at approximately 20 tonnes and annual emissions at around 5,565 tonnes. Key challenges in CO₂ transportation include natural hazards like flooding, geological obstacles, technical issues related to maintaining cold temperatures and safety protocols, and regulatory hurdles such as obtaining permits and ensuring compliance with environmental regulations.

A new mangrove core record for Eastern Thailand: chemical characterization of bulk organic sediment by FTIR‒ATR spectroscopy and elemental analysis

Naomi Seaton, Sakonvan Chawchai, Prompong Pienpinijtham, Ludvig Löwemark — Tue, 31 Dec 2024 00:00:00 +0700

The eastern Gulf of Thailand features mixed low-relief geomorphology, characterized by intertidal mudflats, coastal wetlands, and relict sand deposits indicative of prograding barrier systems formed during Holocene regression. While previous research has focused on reconstructing sea-level changes using beach ridge records and mangrove pollen, there has been no comprehensive investigation into organic geochemical archives. This work aims to provide a new mangrove core record for Eastern Thailand, focused on chemical characterization of organic sediments and proxy reconstructions of relative environmental changes with depth, complementary to growing literature on coastal paleoenvironmental change in this region of the Gulf of Thailand. This research adopts an innovative approach to reconstructing environmental change by analyzing the chemical composition, relative sources, and cycling dynamics of mangrove organic matter, employing loss-on-ignition (LOI), elemental analyses, and Fourier-transform infrared (FT-IR) spectroscopy techniques. The PEM stratigraphic units encompass nutrient-poor surface tidal wash, organic-rich mangrove soils with active humus formation, and basal shallow marine sands with low organic content and high-energy horizons of fragmentary shells. Enhanced organic decomposition is evident in bioturbated surface sediments, while high total organic carbon to total nitrogen (TOC/TN) ratios indicates substantial allochthonous contributions from mangrove leaf litter and detrital organic matter via runoff from the Prasae River. Fluctuating TOC/TN values and FT-IR absorbances at 2925–2905 cm⁻¹ and 3300 cm⁻¹ reflect significant mixing between terrestrial and aquatic organic matter, linked to dynamic sea-level changes and increasing riverine inputs. The organic mangrove soils exhibit FT-IR absorption peaks for phenolic and aromatic compounds at 1630 cm⁻¹, indicating advanced humification stages, while the basal sands preserve higher proportions of aliphatic hydrocarbons, as indicated by vibrations at 1475 cm⁻¹, suggesting influences from grain size, sulfur-reduction pathways, and the inhibitory effects of high phenolic content on organic carbon preservation.

STRUCTURAL CHARACTERISTIC OF EARLY EOCENE EXTENSIONAL FAULT IN SONGHKLA BASIN, GULF OF THAILAND

Makorn Sriwiset — Tue, 31 Dec 2024 00:00:00 +0700

The Songkhla Basin is a classic example of a Cenozoic rift basin in the Gulf of Thailand. The basin is 75 km long (N-S) and 30 km wide (E-W). Its primary geometry is strongly influenced by the main N-S to NNW-SSE, east-dipping boundary fault zone on the western side of the basin, forming an elongated half-graben under E-W extension since the Eocene. Many faults strike predominantly orthogonal to the extension direction. In this study, a set of E-W to WNW-ESE, north-dipping extensional faults is mapped based on 3D seismic data, occurring in the early Eocene syn-rift strata. The younger, N-S striking normal faults either cut across or terminate against the older, basement-involved, E-W to WNW-ESE striking normal faults. The presence of both types of fault interactions in the Songkhla Basin suggests the possibility of multiple phases of non-coaxial extension during the Eocene. This study presents the structural characteristics and 3D geometry of the early Eocene extensional faults, with a discussion on tectonic development.

Outcrop Analogue for Basement Exploration in Songkhla Basin, Gulf of Thailand

PANUS HONG — Tue, 31 Dec 2024 00:00:00 +0700

This study focuses on the lithological and structural variations in the pre-Cenozoic rocks of the Songkhla and Phatthalung areas, likely constituting the basement rocks of the offshore Songkhla Basin, where subsurface exploration is limited by seismic resolution. The methodology employed includes field studies and digital outcrop analysis to determine the relationships and patterns of bedding planes, fractures, and folding. Four lithological facies are defined: 1) Sandstone-dominated facies, 2) Shale-dominated facies, 3) Chert facies, and 4) Granite. The fold analysis indicates contraction varying from WNW-ESE to NW-SE. The dominant fracture patterns align with the NW direction, running subparallel to the maximum horizontal stress and perpendicular to the fold axis. Conversely, secondary fracture patterns appear in the NE-SW direction. At the outcrop scale, fracture characterization indicates that open fractures predominantly occur in coarse-grained and poorly sorted sandstone, chert—especially in the forelimb zone—and granite. In contrast, finer sediments and sedimentary rocks adjacent to the granite are typically clay-filled or filled with quartz veins and veinlets. The results are expected to enhance the understanding of the geology at a sub-seismic scale of the pre-Cenozoic fractured basement potential in the Songkhla Basin.

Petrography and Microstructural Analysis along the Klaeng Fault Zone, Eastern Thailand: Insights from Ductile and Brittle Deformation Zones

Kittichai Chansom, Pitsanupong Kanjanapayont — Tue, 31 Dec 2024 00:00:00 +0700

The Himalayan orogeny, resulting from the collision of the Indian and Eurasian plates during the Cenozoic, has significantly influenced the tectonic structures of Thailand and Southeast Asia. This study examines the Klaeng fault zone, a NNW-SSE to N-S strike-slip fault extending from Nong Yai gneiss to the Khao Chamao fault, through microstructural analysis and petrography. Key features such as bulging, subgrain rotation, grain boundary migration, S-C and S-C’ fabrics, mica fish, myrmekites, and 'V'-pull-apart structures reveal dynamic recrystallization and kinematics. The Khao Yaida metagranite and Ban Tha Cham pluton deformed under low to intermediate temperatures and moderate stress during extensional exhumation. While the Khao Chamao experienced from high to low temperatures during the cooling phase of exhumation. Most of ductile deformation coeval to the sinistral movement of the Klaeng fault zone during the Eocene, and later overprinted by late Eocene dextral motion, influenced by the Himalayan orogeny.

THE INFLUENCE OF PRE-EXISTING STRUCTURES ON FRACTURE SYSTEMS IN THE JURASSIC SURAT BASIN, QUEENSLAND, AUSTRALIA

Sirirat Khamsaeng, Sukonmeth Jitmahantakul — Tue, 31 Dec 2024 00:00:00 +0700

Pre-existing structures can influence the spatial distribution and geometry of subsequent fractures in sedimentary basins. In Queensland, Australia, contractional structures in the Permian-Triassic Bowen Basin control fracture development in the overlying Jurassic Surat Basin, where the Precipice sandstone is targeted for geological storage of carbon dioxide (CO₂). Understanding the influence of pre-existing structures in the Bowen Basin on fracture systems in the Surat Basin is vital for the site selection process of CO₂ geological storage projects in Queensland. This study focuses on the NW-SE trending Miles Thrust Fault (MTF) and its associated fault-propagation folds in the Bowen Basin, aiming to understand their influence on fracture systems in the overlying Jurassic succession of the Surat Basin. Results from 3D seismic interpretation and structural reconstruction reveal that the Surat Basin is characterized by localized extensional faults. These faults crest above the fault-propagation folds of the MTF and strike parallel to the NW-SE trending fold axis. An overlapping relay zone of the extensional faults occurs above the bend of the fold axis, suggesting that structural deformation follows the pre-existing structural trend. Strain distribution in the Jurassic succession increases toward the fold hinge, resulting in the highest fracture intensity. Utilizing the Discrete Fracture Networks (DFNs) model, the N-S trending joint (tension) fracture set follows reginal stress associated with the Surat Basin subsidence. Other fractures are strongly controlled by localized stress influenced by the pre-existing MTF.

Investigation of Morphotectonics along the Mae Chan and Nam Ma Fault Zones, Thailand-Laos-Myanmar Borders

Santi Pailoplee — Tue, 31 Dec 2024 00:00:00 +0700

The Mae Chan and Nam Ma faults are well-known as active faults which were in mainland Southeast Asia including the borders of Thailand, Laos, and Myanmar country. In this study, the morphotectonic analysis used various geomorphic indices to evaluate relative tectonic activity in the study area. A digital elevation model from the Advanced Spaceborne Thermal Emission Radiometer (ASTER) was chosen to create the watershed delineation with an analysis of the geological data and hydrogeological model. The total of hydrogeological basins is 38 basins. The six geomorphic indices to use in this study are mountain front sinuosity (SMF), valley floor width to height ratio (VF), stream length gradient index (SL), basin shape index (BS), basin asymmetry index (AF), and basin hypsometric index (HI). The analysis found that lineament patterns of the Mae Chan and Nam Ma fault mainly trend in the NE-SW direction. The result of the calculated geomorphic index reveals the low values of SMF index between 1.05-4.84, the low values of VF index from 0.42 to 25.36, the high values of SL index, a wide range of values of BS index between 1.00-3.60, AF index between 13.15 to 88.01 and the low values of HI index between 0.11 to 0.40 to facilitate with the active tectonic landforms in the study area.