Granites and Mineral Belts: I – Southern Thailand

Sun, 29 Dec 2024 00:00:00 +0700

Granites under investigation in southern Thailand are divided into 3 belts, namely Eastern Belt, Central Belt, and Western Belt, and each belt lies approximately in the north-south direction. These granite belts with the overall length of at least 2,800 km form parts of the main granite belts of the country and Mainland Southeast Asia. The granites of the Eastern Belt occur as small plutons in the southernmost part of Thailand and perhaps extend from the Loei tectonic belt. The objectives of this research are to document geology of these granites, distribution of mineral deposits and belts, and results on magnetic susceptivity and radioactives of the studied granites. Field investigation shows that granites exhibit both equigranular and porphyritic textures. Both have blackish gray to white colours, and leucogranites are more common in the Western Belt. Two granite suites are classified based on mineralogical criteria, and they can be separated tectonically by the Pattanni Suture. The first suite is hornblende – biotite granites and biotite granites mainly occurring in the Eastern Belt. On the basis of petrochemical data, they belong to the I-type affinity and magnetite granite suites with the inferred ages of 280 - 222 Ma. The second type includes the biotite – muscovite granites and biotite granites which genetically belongs to the S-type affinity and ilmenite series. These granites occurred in the Central Belt occurring in 227 – 200 Ma and the Western Belt with the ages ranging from 80 to 55 Ma. Based on both field and economic geology data, the mineral belts identified belong to Sn-W-REE belt and lies within the Western and Central belts. Moreover, gold and copper mineral belt can also be identified and lies within the Eastern Belt and perhaps located within the Loei tectonic belt. Additionally, it is recognized that biotite - muscovite granites related to Sn – W mineral deposits invariably yield the higher contents of radioactive elements and lower contents of magnetic susceptibilities than the hornblende -biotite granites. This scenario can help to delineate more appropriate mineral zonation and potential mining areas within the region.

Geological Factors Contributing to Landslide Incident in Malaysia - Case Study Batang Kali Landslide Disaster, Hulu Selangor, Selangor.

Sun, 29 Dec 2024 00:00:00 +0700

The Batang Kali landslide that occurred at 2.08 a.m. on 16 December 2022 had struck almost entirely the agriculture and campsite areas of Father's Organic Farm, Batang Kali, Hulu Selangor, Selangor. The deadly landslide claimed 31 lives including 13 children and 61 survivors were rescued. The search and rescue (SAR) operation was carried out immediately and continued for nine days before it ended after the last victim was found. The Department of Mineral and Geoscience Malaysia (JMG) was informed of the event and actively involved in conveying geological information during the SAR operation. JMG was also responsible for conducting a forensic investigation to understand the geological factors that contributed to this catastrophic event. An extensive field geological study including LiDAR data capture, geophysical surveys, geological surface mapping, hydrogeological, and in situ field testing were carried out. These data were analyzed to ascertain the causal geological factors and establish of subsurface profile for landslide simulation modeling. The landslide is classified as a complex which is a combination of rotational slide and earth flow. The landslide body measured approximately 550m long, 110m wide, and 14m deep with 282,170m³ total estimated volume of debris which mainly consists of sandy silt beside block boulders and tree trunks. Analyses indicate that the colluvium layer which is deposited at the foot slope and the groundwater regime have contributed significantly to the failure. Landslide simulation modeling shows the velocity of the flow is 13.2m/s with the average thickness of the accumulation zone ranging from 0.8m to 10.5m. The result from the investigation also indicates that geological causal factors should be taken into consideration in slope repair works and mitigation measures.

Thai Geoscience Journal

Granites and Mineral Belts: I – Southern Thailand

Geological Factors Contributing to Landslide Incident in Malaysia - Case Study Batang Kali Landslide Disaster, Hulu Selangor, Selangor.