Dating multiple generation of zircons from granites and gneiss from Thailand: Implication for the crustal evolution of the Sibumasu terrane

• Published in: Journal of Asian earth sciences Vol. 190; p. 104148
• Main Authors: Kanjanapayont, Pitsanupong, Klötzli, Urs, Frank, Nils
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2020
• Subjects: Sibumasu; Thailand; Two-step granitic magmatism; U-Pb ages; Zircon; U-Pb ages; Sibumasu; Two-step granitic magmatism; Thailand; Zircon
• ISSN: 1367-9120; 1878-5786
• DOI: 10.1016/j.jseaes.2019.104148

[Display omitted] •Inherited zircon core of granite suggests that granitic magma was derived from Neo-Proterozoic to Paleozoic materials.•First magmatic crystallization derived from anatexis melting during the Middle Triassic.•Second magmatic crytallization was related to cooling during the Late Triassic.•Sibumasu and Indochina collision caused two-step magmatic evolution of the granites in Sibumasu terrane. The widespread granitic rocks of the Sibumasu terrane were emplaced during the collision of the Sibumasu and Indochina in the Triassic. Previous studies have suggested that each granite had a simple, single-step magmatic evolution. In situ LA-MC-ICP-MS U-Pb zircon dating of granites and gneiss from Thailand revealed the evolution of these rocks: Inherited zircon core ages (515 ± 130 Ma) from a granite of the Chonburi pluton in the Central-Granitoid Belt are coeval with an orthogneiss protolith age (513.6 ± 9.2 Ma) from Hua Hin area. Similar Cambrian ages were also reported from the Khao Tao area in southern Thailand. Moreover, there are a series of inherited zircon core ages from Neo-Proterozoic (1017 ± 43 and 984 ± 56 Ma), Ordovician (449 ± 26 Ma), Devonian (385 ± 15 Ma), Carboniferous (316 ± 12 Ma) to Permian (276 ± 31 and 266 ± 12 Ma). Taken together, these Neo-Proterozoic to Permian protolith ages are interpreted to represent the basement of the Sibumasu terrane in Thailand. Two magmatic zircon growth events can be distinguished at approximately (a) 241.8 ± 8.2 to 235 ± 12 Ma and (b) 230.6 ± 3.4 to 213.4 ± 3.0 Ma. We concluded that the Sibumasu and Indochina collision during the Triassic caused a two-step magmatic evolution of the granites of the Sibumasu terrane. The first magmatic crystallization during the Middle Triassic corresponded to the Sibumasu and Indochina collision, and the second magmatic crystallization during the Late Triassic was related to the late-collisional stage.