Geochemical and radiogenic isotopic signatures of granitic rocks in Chanthaburi and Chachoengsao provinces, southeastern Thailand: Implications for origin and evolution. Issue 8 (1st December 2022)

• Record Type: Journal Article
• Authors: Uchida, Etsuo; Nagano, Shinya; Niki, Sota; Yonezu, Kou; Saitoh, Yu; Shin, Ki-Cheol; Hirata, Takafumi
• Is Part Of: Journal of Asian earth sciences. Issue 8(2022)
• Publication Date: 2022-12-01
• Subjects: Granite -- Southeastern Thailand -- Geochemical signature -- Sr-Nd isotope ratios -- Zircon U-Pb dating -- Tectonic setting; Earth sciences -- Asia -- Periodicals; 555.05
• DOI: 10.1016/j.jaesx.2022.100111
• Languages: English
• ISSNs: 2590-0560

Abstract

Highlights: Geochemical and isotopic signatures of five granitic bodies in SE Thailand were investigated. The granitic rocks are classified as I- to A-type and ilmenite series with negative Eu anomalies. Zircon U-Pb dating yields ages of 208–214 Ma except for one granitic body (55 Ma). Nd-Sr isotopes suggest continental crust material had a strong influence on the granitic bodies. The study area is concluded to belong to the Sukhothai zone as well as SW Cambodia. Abstract: The Chanthaburi, Pliew, Klathing, Khao Cha Mao, and Khao Hin Son granitic bodies in Chanthaburi and Chachoengsao provinces in southeastern Thailand, which are located on the southwestern side of the Mae Ping Fault and eastern side of the Klaeng Fault, were investigated. In this study, magnetic susceptibility measurements, whole-rock chemical composition and Nd-Sr isotope analyses, and zircon U-Pb dating were conducted on these granitic bodies. The surveyed granitic rocks are classified as I- to A-type granites, are of the ilmenite series, and show clearly negative Eu anomalies, which suggest they formed under reducing conditions. Nd-Sr isotope ratios indicate continental crust material involvement in the formation of these granite bodies. The magnetic and geochemical signatures are similar to those of granite bodies in southwestern Cambodia. The study area is thus considered an extensional area of southwestern Cambodia, corresponding to the Sukhothai Zone (the Chanthaburi-Kampong Chhnang Zone). Zircon U-Pb dating yields ages of 208–214 Ma (the Late Triassic) for granite bodies except for the Khao Cha Mao granitic body, which dates to 55 Ma. The former age corresponds to the collision time of the Sibumasu and Indochina terranes, and the latter age is likely related to the collision time of the Indian and Eurasian continents.