Petrochemistry of granitic rocks in Tha Pai area, Mae Hi sub-district, Pai district, Mae Hong Son province, Northern Thailand

Granitic rocks in the Ban Tha Pai area, Mae Hi sub-district, Pai district, Mae Hong Son province, are located in the western line of the Central Granitic Belt in northern Thailand. These granitic rocks are in N-S orientation and have a Triassic age. Petrographic investigation of the granitic rocks indicates that they are monzogranite with medium to coarse-grained porphyritic texture. Mineral compositions of them mainly consist of quartz, K-feldspar, and plagioclase, with minor biotite and small amounts of muscovite, apatite, zircon, titanite, and opaque minerals. Geochemical investigation of the granitic rocks indicates that they are in sub alkaline series and almost totally of high-K calc-alkaline affinity. Furthermore, the granitic rock samples were S-type granite and peraluminous rock. According to tectonic discrimination diagrams, the granitic rocks might have formed in an orogenic environment

Archaeological Distribution of Geoheritage for Geotourism Development in Nakhon Sawan Province, Thailand

Nakhon Sawan Province is located in Upper Central Thailand, where the Chao Phraya River, the vital river of Thailand, begins. According to the distribution of the archaeological sites, the related geological features were divided into two groups by geodiversity scope: (1) hydrological sites - Chao Phraya river, Bueng Boraphet lake, (2) speleological sites - Tham Phet-Tham Thong cave and Khoa Nor mountain. The hydrological sites are the primary water resources of local people since many hundred years, including transportation, agriculture, and fishery, so there are many archaeological sites around there. In addition, the speleological sites are covered with limestones intruded by the granitic rocks, which has caused ore deposition in the form of skarn. The evidence of antiquities in the archaeological site near speleological sites suggests that ancient people discovered and produced their ores, notably iron in the studied area. Based on inventory, characterization, classification, and assessment methods, this preliminary geoarchaeology study can support Nakhon Sawan to promote geotourism for sustainability by their stunning geological features, fantastic nature as well as beautiful culture, both past and present

Geochemical characteristics of arc fractionated I-type granitoids of eastern Tak Batholith, Thailand

The Tak Batholith is located in the western part of Thailand’s eastern granitoid belt. To better understand the geochemical characteristics of granitoid and identify their occurrence, rock samples collected from the eastern part of the Tak Batholith were used for petrographical, mineralogical, and geochemical analyses. According to field investigation and lithology, petrography classifies these granitic rocks as medium-grained granodiorite and granodioritic dike. The granodiorites are composed chiefly of plagioclase, orthoclase, quartz, hornblende, and biotite, with tiny amounts of zircon, apatite, and opaque minerals. Meanwhile, the granitic dike shows a highly porphyritic texture, presenting mostly plagioclase phenocrysts, with a small amount of orthoclase and unidentified mafic phenocrysts sitting in a fine-grained groundmass comprising K-feldspar and quartz with a small amount of plagioclase and present granophyric intergrowth. Geochemical data of the amphiboles classified them as Ferro-edenite symbolizing the I-type granite. Whole-rock geochemistry indicates that these rock suites are I-type metaluminous granodiorite, and diorite fractionated from the high K calc-alkaline magma melted from the mafic crust of arc magmatism agreeable with the enrichment of large ion lithophile elements and depletion of highfield-strength elements, and rare earth element patterns

Geochemistry and provenance of Mesozoic sandstones in Khon Kaen Geopark: Implication for tectonics of the western Khorat Plateau of Thailand

Khon Kaen Geopark, representing an area of dinosaur fossil diversity, was selected for investigations to reveal the origin and tectonic setting of the Khorat Group. The area occupied by Mesozoic sedimentary rocks of four formal formations of the Khorat Group, namely the Phra Wihan Formation (PWF), Sao Khua Formation (SKF), Phu Phan Formation (PPF), and Khok Kruat Formation (KKF). A field investigation and macroscopic observations suggested that the immature sedimentary rocks of the study area are mainly clast-supported, pebbly sandstone and siltstone with few calcretes. The 50 rock samples that were selected for petrographical and geochemical investigations revealed that the sandstones of the PWF and PPF are quartz arenite and sublitharenite, with some subarkose, whereas those of the SKF are mainly subarkose and sublitharenite. In addition, the KKF dominantly presents sublitharenite with pebbles and calcretes. Mesozoic sandstones contain quartz, feldspars, various types of rock fragments, and accessory minerals (biotite, muscovite, zircon, and tourmaline), with siliceous, ferrous, and calcareous cement. Petrographic (Q–F–L) and geochemical (major and trace element) data suggested that the sources of sediments are mostly quartzose sedimentary rocks and some felsic-intermediate igneous rocks. Chondrite-normalized rare earth element patterns indicated that the origins of the studied sandstones are quartzose sedimentary rocks deposited in a passive continental margin or an upper continental crust. Geochemical traits of the sedimentary successions demonstrated that the provenance of the Khorat Basin prior to reworking by fluvial processes was situated in the passive continental margin or recycled orogen of the paleo-volcanic arc during the Mesozoic period

Geochemistry and provenance of Mesozoic sandstones in Khon Kaen Geopark: Implication for tectonics of the western Khorat Plateau of Thailand.

Khon Kaen Geopark, representing an area of dinosaur fossil diversity, was selected for investigations to reveal the origin and tectonic setting of the Khorat Group. The area occupied by Mesozoic sedimentary rocks of four formal formations of the Khorat Group, namely the Phra Wihan Formation (PWF), Sao Khua Formation (SKF), Phu Phan Formation (PPF), and Khok Kruat Formation (KKF). A field investigation and macroscopic observations suggested that the immature sedimentary rocks of the study area are mainly clast-supported, pebbly sandstone and siltstone with few calcretes. The 50 rock samples that were selected for petrographical and geochemical investigations revealed that the sandstones of the PWF and PPF are quartz arenite and sublitharenite, with some subarkose, whereas those of the SKF are mainly subarkose and sublitharenite. In addition, the KKF dominantly presents sublitharenite with pebbles and calcretes. Mesozoic sandstones contain quartz, feldspars, various types of rock fragments, and accessory minerals (biotite, muscovite, zircon, and tourmaline), with siliceous, ferrous, and calcareous cement. Petrographic (Q-F-L) and geochemical (major and trace element) data suggested that the sources of sediments are mostly quartzose sedimentary rocks and some felsic-intermediate igneous rocks. Chondrite-normalized rare earth element patterns indicated that the origins of the studied sandstones are quartzose sedimentary rocks deposited in a passive continental margin or an upper continental crust. Geochemical traits of the sedimentary successions demonstrated that the provenance of the Khorat Basin prior to reworking by fluvial processes was situated in the passive continental margin or recycled orogen of the paleo-volcanic arc during the Mesozoic period

Lithological data of sedimentary rocks in Khon Kaen Geopark.

Lithological data of sedimentary rocks in Khon Kaen Geopark.</p

Stratigraphic columns in nine dinosaur excavation sites distributed in the Sao Khua Formation, Khon Kaen Geopark (stratigraphical and paleontological data from [28].

Stratigraphic columns in nine dinosaur excavation sites distributed in the Sao Khua Formation, Khon Kaen Geopark (stratigraphical and paleontological data from [28].</p

Diagrams of plotted petrographic data of sedimentary rocks in Khon Kaen Geopark.

(A) Qt–F–Lt name classification diagram [34], (B) Qt–F–Lt, and (C) Qm–F–Lt diagrams with tectonic fields [35], (D) Lm–Lv–Ls diagrams with tectonic fields [36], and (E) Qp–Lv–(Ls+Lm) diagrams with tectonic fields [37]. Qt: total quartz, Qm: monocrystalline quartz, Qp: polycrystalline quartz, F: feldspar (plagioclase and K-feldspar), L: lithic fragment, Lt: lithic fragment and polycrystalline quartz, Ls: sedimentary lithic grains, Lv: volcanic lithic grains, Lm: metamorphic lithic grains.</p

Ternary trace elements classification of sedimentary rocks in Khon Kaen Geopark.

(A) La-Th-Sc discrimination diagram [45], (B) La-Th-Sc discrimination diagram [44], (C) Th-Sc-(Zr/10) discrimination diagram [46], and (D) La-Th-Sc discrimination diagram [47].</p