Evolution of supracrustal rocks of the Indochina Block: Evidence from new detrital zircon U–Pb ages of the Kontum Massif, Central Vietnam

Abstract

The Kontum Massif and the Truong Son Belt, central Vietnam are the magmatic-metamorphic massifs (belts) of the Indochina Block. These two massifs (belts) underwent two independent orogenic events during Ordovician-Silurian and Permian-Triassic ages. However, due to the strong overprint of these two orogenic events, the evidence of any preexisting (e.g., Precambrian) tectono-thermal events have become extremely poor. Hence, the Precambrian age components of the Indochina Block have not been fully revealed, and their implication is not well-understood. It is well known that such 'lost memories' of the older continental rocks or source crustal materials are sometimes preserved in the sedimentary basins. Keeping that goal in mind, we have investigated the LA-ICP-MS detrital zircon U-Pb dating for three sedimentary and metasedimentary rocks in the Kontum Massif and southern part of the Truong Son Belt, Indochina Block, central Vietnam to unravel the Precambrian episodes of the Indochina Block, if any. Two Triassic (meta)-sedimentary rocks reveal two significant age clusters of latest Carboniferous to Triassic (~300-230 Ma) and Early Paleozoic (~480-410 Ma), with the conspicuous lack of the 400-320 Ma zircon grains. Abundant Permian detrital zircon grains in Triassic metaquartzite from the Kontum Massif document that the subduction-related magmatism before the continental collision played an important role in the growth of the Kontum Massif. In contrast to these two (meta)-sedimentary rocks, the detrital zircon spectra of metaquartzite from the Kontum Massif show the most significant age peak of~1780 Ma and abundant Archean zircon grains (16%). Furthermore, the oldest detrital zircon shows the Paleoarchean age ( 207 Pb/ 206 Pb spot age of 3314 ± 22 Ma). The metaquartzite was metamorphosed in the Early Paleozoic (~414 Ma). The youngest detrital zircon grain yields the 207 Pb/ 206 Pb spot age of 1359 ± 85 Ma. Hence, the approximate depositional timing of the protolith of metaquartzite was in Mesoproterozoic time. The newly obtained detrital zircon data indicate a significant contribution of the Paleoarchean to Paleoproterozoic crustal materials during the deposition of the quartzite in the Kontum Massif. The Kontum Massif had developed as a different unit in the Precambrian period from the Truong Son Belt as well as the southwestern Yangtze Block due to their different Precambrian provenance. This study reveals a new clue that the Kontum Massif was one of the Precambrian blocks in the Southeast Asian massifs.

Closing of the east Palaeo‐Tethys Ocean: Source–sink records from Middle Triassic sediments, Hainan Island, China

“…(a–d) Synthesis and comparison of Kernel Density Estimate (KDE) diagrams of detrital zircon U–Pb ages. (a) Lingwen Formation (this study); (b) central Vietnam (data from Kenta et al, 2021); (c) west of the Ailaoshan fault (data from Halpin et al, 2016; Liu, Peng, et al, 2022; Xu, Xia, Lai, Long, & Huang, 2019); (d) southwest margin of the SCB (data from Chai et al, 2022; Duan et al, 2018; Hu et al, 2017; Liu, Peng, et al, 2022; Xu, Xia, Lai, Long, & Huang, 2019; Yang et al, 2012a); (e) southeast margin of the SCB (Hu et al, 2015; Kong, Xu, Tao, et al, 2022; Xu et al, 2018). MDS diagram based on Cross‐correlation, Likeness, Kuiper test V value and K–S test D value (e–h), the solid line represents the closest neighbour.…”

“…However, previous studies have not identified Neoproterozoic magmatic rocks on Hainan Island. Detrital zircons of this age group are also rare in clastic rock from the Truong Son belt and the Kontum Massif in the IB (Kenta et al, 2021; Wang, Lin, Faure, Lepvrier, et al, 2021; Wang, Zhang, Qian, Wang, et al, 2021). However, detrital zircons aged 750–1000 Ma were present in the SCB (Liu, Hu, Chen, et al, 2021; Wang et al, 2019; Wang, Wen, et al, 2018; Zhou, Liang, Liang, Jiang, Wang, et al, 2015b), indicating that the surrounding SCB and Yangtze Craton were the source areas for Hainan Island during this period.…”

“…Considering the above question, in this study, the detrital zircon ages of the Middle Triassic strata in central Vietnam (Kham Duc Complex in Kontum Massif, Kenta et al, 2021), west of the Ailaoshan fault (Halpin et al, 2016;Liu, Peng, et al, 2022;Xu, Xia, Lai, Long, & Huang, 2019) and on the southwestern (Chai et al, 2022;Duan et al, 2018;Hu et al, 2017;Liu, Peng, et al, 2022;Xu, Xia, Lai, Long, & Huang, 2019;Yang et al, 2012a) and southeastern margins of the SCB (Hu et al, 2015;Kong, Xu, Tao, et al, 2022;Xu et al, 2018), were collected and compared with those of the Lingwen Formation (Figure 15a-e). In the figures, it can be observed that the detrital zir- (Wang, Lin, Faure, Lepvrier, et al, 2021).…”

Zircon U-Pb Geochronology, Geochemistry, and Sr-Nd-Hf Isotopic Composition of Ben Giang-Que Son Complex in the Southern Truong Son Belt: Implications for Permian–Triassic Tectonic Evolution

“…Geologists from Vietnam and abroad argue that the Indochina block consists of three main structural zones on Vietnamese territory: the Kontum massif in central Vietnam, the Da Lat zone in the south, and the TS belt in the north [3,9,[16][17][18] (Figure 1a). The Song Ma suture borders to the northern margin of the TS belt, which is located in north-central Vietnam [1,2,5,[19][20][21][22].…”

Metamorphic evolution of the pelitic and mafic granulites from Daltonganj, Chhotanagpur Granite Gneiss Complex, India: Constraints from zircon U–Pb age and phase equilibria modelling

“…Zircon separation and mount‐making processes are the same as those described in Kawaguchi, Minh, Hieu, Cuong, and Das (2021). Zircon separation was accompanied by the panning method using the whole‐rock powder with water.…”