° 98°E 100 ° g g GEOLOGICAL MAP 20 N V OF THAILAND g D-C D-C P g Mz 0 50 100 150km V Cz g Mz CHIANGMAI TR TR m P Cz g Cz g P D-C 18° 18° P C-S TR V P D-C g K D-C V Cz g C-S LOEI Mz K Mz P g g V TR m SUKHOTHAI D-C TR Mz P K Cz Mz Mz V g P 16° Mz TR Mz Mz P m V 16° V K g K g P Cz V V C-S P D-C KHORAT C-S C-S K P g g Cz V Mz g V V V g Mz 14° P KANCHANABURI 14° Cz P BANGKOK V TR g V TR C-S g m P P g g Cz m V D-C TR V P m CHANTHABURI m Mz Cz P TR 12° V ° Cz Mz 12 g K P Mz SEDIMENTARY ROCKS g 10° Cz g Mz Cenozoic g g P g K Cretaceous P Mz Mesozoic (undifferentiated) m TR P Triassic Mz g P Permian (locally including Triassic and Carboniferous) g P D-C Devonian-Carboniferous (locally including Silurian and Permian) ° KRABI Cz 8 PHUKET Mz Mz C-S Cambrian-Silurian D-C g IGNEOUS & METAMORPHIC ROCKS Mz g Granite/ V SONGKHLA Cenozoic C-S Granodiorite basalts m Gneiss, Cz V Acid volcanic C-S migmatite TR rocks g D-C Basic/ultrabasic rocks Cz g 6° ° 98 E 100° 102° 104° 106° Modified from the Thailand Department of Mineral Resources geological map, 1:2,000,000 scale, 1999. Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/4323950/9781862393943_backmatter.pdf by guest on 29 September 2021 Appendix Radiometric ages of Thailand rocks Compiled by M. J. CROW This Appendix of Radiometric Ages lists the radiometric age The radiometric data provide information on the temperature determinations (using different mineral and isotopic systems) of ranges below which the mineral or isotopic systems effectively Thai rocks and minerals that have been published up to 2010. stabilised. These temperature ranges are summarized in Table A.1. They are listed in decreasing-age order, and grouped into periods However, such temperature data can be affected by the mineral following the scheme of Gradstein et al. (2004). structure, grain size, and previous thermal history of the samples The sample locations are described with reference to the regions investigated. of Thailand (Fig. 1.1), the tectonic units or zones (Fig. 19.1), the Table A.2 summarises the conclusions of the radiometric inves- granite provinces and belts (Figs 16.3, 16.5 and 16.6), the distri- tigations, and it will be noted that some authors did not publish the bution of volcanic rocks (Figs 15.1 and 15.2), the major fault precise geographical locations of the rock and mineral outcrops that zones (Fig. 11.1), and the simplified geological map (at the back they sampled and analysed. In consequence, users and interpreters of the book). The abbreviations used are shown at the bottom of of these radiometric age data are advised to study the cited publi- the table. It should be borne in mind that the interpretation of the cations for details of the locations, as well as details of the analytical tectonic zones, in particular the position of their boundaries methods and the calculations employed in obtaining the ages within and beyond the borders of Thailand, continues to be an quoted. active topic of investigation and discussion in which the interpret- ation of the radiometric age data plays an important part. Abbreviations Table A.1. Summary of temperatures below which mineral/isotopic Location Abbreviations systems effectively become stable in the crust (modified after Carter 1999) CC, Core Complex; CGB, Central Granite Belt; CPR, Central Plains Region; EGB, Eastern Margin Granite Belt; ICB, Indochina Block; Temperature range (8C) IZ, Inthanon Zone; KG, Khorat Group; KMFZ, Khlong Marui Fault below which the system Zone; LFB, Loei Fold Belt; LP, Lower Peninsula; MPFZ, Mae Ping Dating system Mineral becomes effectively stable Fault Zone; NAN, Nan Suture Zone; NE, Northeast Region; NR, Northern Region; NSFM, Northern Sector Frontier Monocline; U/Th/Pb Zircon 800–900 PR, Peninsular Region; SE, South East Region; SSFM, Southern Rb–Sr Amphibole 500–600 Sector Frontier Monocline; SUK, Sukhothai Zone; TPFZ, Three U/Th/Pb Monazite 500–600 Pagodas Fault Zone; UP, Upper Peninsula; WGP, Western 40Ar/39Ar Amphibole 500 Granite Province; WGB, Western Margin Granite Belt; WR, K–Ar Muscovite 400–300 Western Region. U/Pb Apatite 400–300 40 39 Ar/ Ar Muscovite 350–250 Dating Method Abbreviations K–Ar Biotite 350–250 Rb–Sr Biotite 300 WR, Whole Rock; IA, Integrated Age; TF, Total-Fusion Age; IS, 206 238 40Ar/39Ar Biotite 300–200 Reversed Isochron Age; U–Pb, isotope ratio Pb/ U plotted 207 235 Fission Track Zircon 320–200 against isotope ratio Pb/ U; LIA, Lower Intercept Age; UIA, 40Ar/39Ar K-feldspar 300–150 Upper Intercept Age; LA-ICP-MS, Laser Ablation–Inductively Fission Track Apatite 110–60 Coupled Plasma- Mass Spectrometer; SEM, Scanning Electron Microscope; TIMS, Thermal Ionisation Mass Spectrometer. Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/4323950/9781862393943_backmatter.pdf by guest on 29 September 2021 on 29September 2021 by guest Downloaded fromhttp://pubs.geoscienceworld.org/books/book/chapter-pdf/4323950/9781862393943_backmatter.pdf 594 Table A.2. Chronological list of radiometric ages for Thailand, published upto 2010 Lithology and sample numbers Tectonic unit Location Dating method Age (Ma) References Precambrian (>542 Ma) Zircon in muscovite–biotite orthogneiss IZ (CC) Doi Inthanon Core Pb–U UIA (inherited age) 3300 Dunning et al. (1995) (WY90-63) in main orthogneiss unit (Fractions Complex Z1 & Z2) Detrital zircons in basaltic sandstone IZ (CB) 40 km NW Chiang Dao U–Pb LA-ICP-MS Hara et al. (2010) Age range (Ma): 2500, 1800–1600, 1300–700, 500, 450, 250–220 Zircon (5 crystals) med. grained, well sorted KG (ICB) Sao Khua Fm. U–Pb SHRIMP 2535 + 15 Carter & Moss (1999) sandstone Zircon (28_4), coast exposure (range of zircon TPFZ (SE) 32.5 km WSW Klaeng U–Pb LA-ICP-MS 2524 + 58 Geard (2008) ages from 493–2524 Ma) Zircon (15 crystals) med. grained, well sorted KG (ICB) Khok Kruat Fm. U–Pb SHRIMP 2500 + 14 Carter & Moss (1999) sandstone Zircon (5 crystals) med. grained, well sorted KG (ICB) Nam Phong Fm. U–Pb SHRIMP 2468 + 14 Carter & Moss (1999) sandstone Zircon (5 crystals) med. grained, well sorted KG (ICB) Phra Wihan Fm. U–Pb SHRIMP 2450 + 16 Carter & Moss (1999) sandstone Orthogneiss (Th22/95) 5 zircon fractions 7 km IZ (SE) 10180003000E; 1381704500N U–Pb UIA 2402 2 370/þ460 Hansen & Wemmer (2011) SW Chonburi Zircon in orthogneiss (Th-5-95) 5 size fractions TPFZ 10182500500E; 1283903000N Pb–U UIA 2200 Hansen & Wemmer (2011) Zircon average age of inheritance (LP-3A) SUK Lampang Volcanic Belt U–Pb TIMS 2074 Barr et al. (2000) Zircons in orthogneiss (ThM 45/92) IZ (CC) 9881603600E; 1880902700N U–Pb UIA 1956 2 200/þ230 Hansen & Wemmer (2011) APPENDIX Zircon (5 crystals) med. grained, well sorted KG (ICB) Nam Phong Fm. U–Pb SHRIMP 1839 + 9 Carter & Moss (1999) sandstone Zircon (5 crystals) med. grained, well sorted KG (ICB) Sao Khua Fm. U–Pb SHRIMP 1832 + 7 Carter & Moss (1999) sandstone Zircon (5 crystals) med. grained, well sorted KG (ICB) Phra Wihan Fm. U–Pb SHRIMP 1813 + 7 Carter & Moss (1999) sandstone Zircon (20 crystals) med. grained, well sorted KG (ICB) Khok Kruat Fm. (ICB) U–Pb SHRIMP 1799 + 8 Carter & Moss (1999) sandstone Zircon from paragneiss (ThM 96/92) IZ/MPFZ 9980701900E; 1680504200N U–Pb UIA 1732 þ 580/2470 Hansen & Wemmer (2011) Zircon in paragneiss (ThM 4/87) MPFZ N105/Km 16.3 U–Pb UIA 1628 þ 340/2300 Hansen & Wemmer (2011) 9885902400E; 1684803500 Zircon in biotite augen orthogneiss (WY 90-26) CC (IZ) Doi Inthanon Core Pb–UIA (inherited age) 1118 þ 285/2175 Dunning et al. (1995) from granodioritic sheet east side of core Complex orthogneiss Zircon (inherited) (13_9) amphibolite facies TPFZ (SE) 27 km W Klaeng U–Pb LA-ICP-MS 1118 + 75 Geard (2008) granite gneiss 2 zircon & 1 monazite fraction from a porphyritic IZ (CC) Mae Cham pluton Pb–U LIA (inherited age) 846 þ 120/2130 Dunning et al. (1995) foliated granite (WY90-119) Zircon in paragneiss (Th-4-95) 3 size fractions TPFZ 10182500500E; 1283903000N Pb–U UIA 668 + 110 Hansen & Wemmer (2011) Zircon (14 grains) in (28_5), coast exposure TPFZ (SE) 32.5 km WSW Klaeng U–Pb LA-ICP-MS 552max + 20 Geard (2008) Zircon (12 grains) in (28_9), coast exposure TPFZ (SE) 32.5 km WSW Klaeng U–Pb LA-ICP-MS 543max + 6 Geard (2008) Early Palaeozoic (416–542.00 Ma) Zircon in granitic mylonite (BRC 36) IZ (CC) Doi Suthep complex U–Pb concordia Inherited 493 & 1567 Barr et al. (2010) ages (upper intercepts) Zircon (28_4), coast exposure TPFZ (SE) 32.5 km WSW Klaeng U–Pb LA-ICP-MS 493 + 7 Geard (2008) Zircon (2 grains) in (28_4), coast exposure TPFZ (SE) 32.5 km WSW Klaeng U–Pb LA-ICP-MS 487max + 9 Geard (2008) Zircons from granodiorite inclusion in serpentinite NAN (SE) Sa Kaeo zone U–Pb UIA 486.5 + 5.4 Hada et al. (1999) matrix of Thung Kabin melange (ThM-1) on 29September 2021 by guest Downloaded fromhttp://pubs.geoscienceworld.org/books/book/chapter-pdf/4323950/9781862393943_backmatter.pdf Zircon (28_4), coast exposure TPFZ (SE) 32.5 km WSW Klaeng U–Pb LA-ICP-MS 483 + 5 Geard (2008) Zircon (5 crystals) med.