40Ar/39Ar ages of granitoids from the Truong Son fold belt and Kontum massif in Laos

Abstract

Geochemical and geochronological studies were conducted on granitoids in central -southern Laos. S -type ilmenite -series granitoids associated with Sn mineralization are distributed in the Truong Son fold belt of central Laos. Plateau ages determined by 40 Ar/ 39Ar incremental heating method for biotite and muscovite of the granitoids range from 253 Ma to 247 Ma and from 244 Ma to 199 Ma in the southwest and northeast of the fold belt, respectively. During this period, the fractionated granites in the early stage are related to mineralization of medium -large Sn deposits. The granitoids of the Truong Son fold belt formed in the Indosinian orogeny are contemporaneous with the Late Permian -Early Jurassic Sn -bearing granites in the Southeast Asian Sn Belt. In contrast, I -type magnetite -series granitoids are distributed in the Kontum massif of southeasternmost Laos. Plateau ages for biotite and previously reported mineral ages of the magnetite -series granitoids range widely from 414 Ma to 252 Ma. The Carboniferous -Permian granitoids represents adakitic characteristics and the Permian adakitic granodiorites are associated with Cu ± Au mineralized quartz veins.

Zircon U–Pb chronology on plutonic rocks from northeastern Cambodia

“…The ages of the first group correspond to magmatic activity in the Loei Fold Belt (260–170 Ma) or Truong Son Fold Belt (290–190 Ma) ( Zaw et al., 2009 , 2014 ; Sanematsu et al., 2011 ; Kawakami et al., 2014 ; Manaka et al., 2014 ; Nualkhao et al., 2018 ). Based on their locations, the plutonic rocks of Phnom Daek, Phnom Koy Rmeas, Svay Leu, Oyadav South, and Phnom Soporkaley were likely formed by magmatic activity in the Loei Fold Belt, which likely extended north of the Mae Ping Fault in Thailand ( Nualkhao et al., 2018 ) ( Figure 6 ).…”

“…The formation of Mainland Southeast Asia was induced by movement of the Indochina, South China, Sibumasu, West Myanmar, and Indian Continent terranes ( Thuy et al., 2004b ; Ferrari et al., 2008 ; Sanematsu et al., 2011 ; Metcalfe 2011 , 2013 ; Searle et al., 2012 ; Morley, 2012 ; Morley et al., 2013 ; Shellnutt et al., 2013 ; Burrett et al., 2014 ; Kamvong et al., 2014 ; Zaw et al., 2014 ; Gardiner et al., 2015 ; Wang et al., 2016 ; Faure et al., 2018 ; Rossignol et al., 2018 ). Many plutonic rocks are distributed in Mainland Southeast Asia.…”

Zircon U–Pb ages and geochemistry of granitoids in the Truong Son terrane, Vietnam: Tectonic and metallogenic implications

“…Many geochronological studies have been conducted for granitoids of Jinshajiang -Ailaoshan -Song Ma area and the neighboring northern Truong Son terrane using Ar-Ar (Lan et al, 2000;Lepvrier et al, 1997Lepvrier et al, , 2004Tong and Vu, 2006;Sanematsu et al, 2011), K-Ar (Tran and Nguyen, 2006) and U-Pb (Carter et al, 2001;Hoa et al, 2008;Liu et al, 2012;Lai et al, 2014;Roger et al, 2014) methods. These data provide different geodynamic interpretations of the magmatism and tectonic evolution, and most of them are focused on the Indosinian magmatic activities.…”

Provenance and tectonic evolution of Lower Paleozoic–Upper Mesozoic strata from Sibumasu terrane, Myanmar

“…Cover rocks mainly consist of Paleozoic to Early Mesozoic marine limestone, shale, and sandstone and Late Mesozoic continental clastics interbedded with volcanic rocks. Mesozoic granite plutons intrude both the northeast and western parts of the Indochina terrane (Sanematsu et al, 2011;Lai et al, 2014). The Simao block, which is the northern extension of the Indochina block (Metcalfe, 2002;Wang et al, 2014), is bounded to the Fig.…”