Fig 1.
Geologic map of Khon Kaen Geopark area showing the location of rock sampling and bedding attitudes, and the geologic section along AB showing the synclinal structure of the Khorat Group rocks.
The stereonet diagrams present the orientation of the bedding planes in each location (A‒F). The geological data is from [9].
Fig 2.
Outcrops of sedimentary rocks in Khon Kaen Geopark.
(A) White sandstone of the Phra Wihan Formation at 48Q 216316E 1852542N, (B) maroon pebbly sandstone of the Sao Khua Formation at 48Q 212405E 1842716N, (C) pebbly sandstone and cross-bedding of the Phu Phan Formation at 48Q 208082E 1841546N, (D) white sandstone of the Phu Phan Formation at 48Q 211484E 1842718N, (E) maroon sandstone of the Sao Khua Formation at 48Q 214392E 1843976N (looking north), and (F) maroon sandstone of the Sao Khua Formation at 48Q 214911E 1844509N (looking south).
Table 1.
Sampling location and petrographic data of studied clastic sedimentary rocks in Khon Kaen Geopark.
Fig 3.
Stratigraphic columns in nine dinosaur excavation sites distributed in the Sao Khua Formation, Khon Kaen Geopark (stratigraphical and paleontological data from [28].
Fig 4.
Photomicrographs in cross-polarized light of sedimentary rocks in Khon Kaen Geopark.
(A) Quartz arenite of Phra Wihan Formation sample no. KK1-3, (B) subarkose of Phra Wihan Formation sample no. KK3-1, (C) sublitharenite of Sao Khua Formation sample no. KK15-1, (D) sublitharenite of Phu Phan Formation sample no. KK13-1, (E) sublitharenite of Sao Khua Formation sample no. KK20-1, (F) sublitharenite of Sao Khua Formation sample no. KK18-1. Qz: quartz, Pl: plagioclase, Afs: alkaline feldspars, Ms: muscovite, Tur: tourmaline, Zr: zircon, Cal: calcite, Sh: shale fragment, Sf: silicified rock fragments, Fs: felsic igneous rock fragments, Lm: limestone fragments.
Fig 5.
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.
Fig 6.
Chemical classification of sedimentary rocks in Khon Kaen Geopark.
(A) log(Fe2O3/K2O) and log(SiO2/Al2O3) fields [38], and (B) log(Na2O/K2O) and log(SiO2/Al2O3) fields after [34].
Table 2.
Whole-rocks analysis for major oxides, trace elements, and REEs of studied clastic sedimentary rocks in Khon Kaen Geopark.
Fig 7.
Tectonic-setting discrimination diagrams for the sedimentary rocks in Khon Kaen Geopark.
(A) FeO+MgO vs. TiO2 fields [41], (B) SiO2–Log(K2O/Na2O) diagram [43], (C) basicity diagram [44, 45], and (D) discriminant function analysis using major oxides [42].
Fig 8.
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].
Fig 9.
Chemical classification to determine source rock compositions of sedimentary rocks in Khon Kaen Geopark.
(A) La/Yb versus Ce diagram [47], (B) La/Th versus Hf diagram [48], and (C) Th/Sc versus Zr/Sc diagram [49].
Fig 10.
Upper continental crust (UCC)-normalized patterns of the KKGp sedimentary rock.
(A) Major-minor oxides and (B) trace elements. Data for UCC are from [51].
Fig 11.
Chondrite-normalized REE patterns of the KKGp sedimentary rocks, Shijia sandstone, granites from Qinling Orogenic Belt, and UCC.
Data for Shijia sandstone, granites from Qinling Orogenic Belt, UCC, and chondrite are from [51–54].
Fig 12.
Simplified scheme of Khorat Group stratigraphy and tectonic setting from the late Triassic to early Cretaceous.
Fig 13.
(A) a simplified map of the Khorat sediments and other basins containing Cretaceous recycled orogen sediments, (B) a tectonic model of the Khorat basin during the Early Cretaceous, and (C) present-day tectonics of the Khorat Plateau. The synthesis of the geotectonic evolution of Thailand is from [86, 87]. The location of the Khorat Basin and transportation (black arrow) of sediments are modified from [32, 70].