Metamorphism in the A Vuong Formation, southern  Truong Son Belt, Vietnam

Sinh Vuong Bui Thi; Ippei Kitano; Tuan-Anh Tran; Can Pham-Ngoc; Ly Vu Hoang; Lien Pham Thi Phuong; Huong Ngo Thi; Cong Tran Quoc

doi:10.15625/2615-9783/23301

Author affiliations

Authors

Vuong Bui Thi Sinh 1-Institute of Earth Sciences, Vietnam Academy of Science and Technology, Hanoi, Vietnam; 2-The Hokkaido University Museum, Hokkaido University, Hokkaido 060-0810, Japan
Ippei Kitano The Hokkaido University Museum, Hokkaido University, Hokkaido 060-0810, Japan
Tuan-Anh Tran Institute of Earth Sciences, Vietnam Academy of Science and Technology, Hanoi, Vietnam
Can Pham-Ngoc Institute of Earth Sciences, Vietnam Academy of Science and Technology, Hanoi, Vietnam
Ly Vu Hoang Institute of Earth Sciences, Vietnam Academy of Science and Technology, Hanoi, Vietnam
Lien Pham Thi Phuong Institute of Earth Sciences, Vietnam Academy of Science and Technology, Hanoi, Vietnam
Huong Ngo Thi Institute of Earth Sciences, Vietnam Academy of Science and Technology, Hanoi, Vietnam
Cong Tran Quoc Institute of Earth Sciences, Vietnam Academy of Science and Technology, Hanoi, Vietnam

DOI:

https://doi.org/10.15625/2615-9783/23301

Keywords:

A Vuong Formation, Truong Son Belt, Anti-clockwise P-T trajectory, Biotite-Chlorite zone, Staurolite zone

Abstract

The A Vuong Formation, located within the southern Truong Son Belt in central Vietnam, comprises low- to high-grade metamorphic rocks that record crucial insights into the region’s tectonic evolution. Our field investigations reveal that it mainly consists of the psammitic and pelitic schists, intercalated with some mafic or siliceous layers, and locally cut by leucocratic veins. The indicative mineral assemblages in the pelitic to psammitic schists define two metamorphic zones: a greenschist-facies biotite-chlorite zone and an amphibolite-facies staurolite zone. Based on conventional geothermobarometry, the peak metamorphic condition in the staurolite zone was estimated at ca. 5.5–8.7 kbar and 590–640℃, followed by a retrograde stage at 4.4–7.4 kbar and 530–570℃. Notably, a porphyroblastic andalusite observed in a pelitic schist from this zone is rimmed by kyanite with a preferred orientation. In addition, it includes kyanite, sillimanite, and an intergrowth of staurolite + quartz as inclusions. These features suggest their equilibrium during the prograde stage, reflecting a pressure-temperature transition from andalusite to kyanite stability. The prograde metamorphic condition is thus constrained at the triple point of andalusite-kyanite-sillimanite. The petrological evidence and estimated metamorphic conditions for the current pelitic schists support a unique anti-clockwise pressure-temperature trajectory, rather than a clockwise one. Its thermobaric feature is well aligned with the amphibolite-facies metamorphism of the neighboring Dai Loc Complex, and contrasts with that of the Kham Duc Complex (Kontum Massif).

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References

Bohlen S.R., Wall V.J., Boettcher A.L., 1983. Experimental investigations and geological applications of equilibria in the system FeO-TiO2-Al2O3-SiO2-H2O. American Mineralogist, 68, 1049–1058.

Bui V.T.S., Osanai Y., Nakano N., Adachi T., Kitano I., Owada M., 2020. Timing of high-grade metamorphism in the Kontum Massif, Vietnam: Constraints from zircon-monazite multi-geochronology and trace elements geochemistry of zircon-monazite-garnet. Journal of Asian Earth Sciences, 187, 104084.

Bui T.S.V., Osanai Y., Nakano N., Kitano I., Adachi T., Tran T.A., Pham B., 2022. Petrology and zircon U–Pb geochronology of pelitic gneisses and granitoids from the Dai Loc Complex in the Truong Son Belt, Vietnam: Implication for the Silurian magmatic-metamorphic event. Journal of Asian Earth Sciences, 226, 105070.

Bui T.S.V., Kitano I., Osanai Y., Nakano N., 2023. Monazite dating of pelitic gneisses in the Dai Loc Complex, Truong Son Belt, Vietnam. International Association for Gondwana Research 2023 Convention and 20th International Conference on Gondwana to Asia, abstract, 78.

Carter A., Roques D., Bristow C., Kinny P., 2001. Understanding Mesozoic accretion in Southeast Asia: Significance of Triassic thermotectonism (Indosinian orogeny) in Vietnam. Geology, 29(3), 211.

Faure M., Nguyen V.V., Hoai L.T.T., Lepvrier C., 2018. Early Paleozoic or Early-Middle Triassic collision between the South China and Indochina Blocks: The controversy resolved? Structural insights from the Kon Tum massif (Central Vietnam). Journal of Asian Earth Sciences, 166, 162–180.

Ferry J.M.T., Spear F.S., 1978. Experimental calibration of the partitioning of Fe and Mg between biotite and garnet. Contribution to Minerology and Petrology, 66(2), 113–117.

Gardner C.J., Graham I.T., Belousova E., Booth G.W., Greig A., 2017. Evidence for Ordovician subduction-related magmatism in the Truong Son terrane, SE Laos: Implications for Gondwana evolution and porphyry Cu exploration potential in SE Asia. Gondwana Research, 44, 139–156.

Henry D.J., Guidotti C.V., Thomson J.A., 2005. The Ti-saturation surface for low-to-medium pressure metapelitic biotites: Implications for geothermometry and Ti-substitution mechanisms. American Mineralogist, 90, 316–328.

Hoisch T.D., 1990. Empirical calibration of six geobarometers for the mineral assemblage quartz + muscovite + biotite + plagioclase + garnet. Contribution to Minerology and Petrology, 104, 225–234.

Holdaway M.J., Lee S.M., 1977. Fe-Mg cordierite stability in high-grade pelitic rocks based on experimental, theoretical, and natural observation. Contribution to Minerology and Petrology, 63, 175–198.

Holdaway M.J., 2001. Recalibration of the GASP geobarometer in light of recent garnet and plagioclase activity models and versions of the garnet-biotite geothermometer. American Mineralogist, 86, 1117–1129.

Hung C., 1996. Geological Map of Vietnam on scale 1:50.000. Hoi An-Da Nang sheet. South Vietnam Geological Mapping Division, General Department of Geology and Minerals of Vietnam.

Jiang W., Yu J.H., Wang X., Griffin W.L., Pham T.H., Nguyen D.L., Wang F., 2020. Early Paleozoic magmatism in northern Kontum Massif, Central Vietnam: Insights into tectonic evolution of the eastern Indochina Block. Lithos, 376–377, 105750.

Kitano I., Bui T.S.V., Osanai Y., Nakano N., Pham B., Hokada T., 2022. The pressure temperature conditions of high-grade pelitic gneisses in the Dai Loc Complex, Truong Son Belt, central Vietnam. The Thirteenth Symposium on Polar Science, abstract.

Le Breton N., Thompson A.B., 1988. Fluid-absent (dehydration) melting of biotite in metapelites in the early stages of crustal anatexis. Contributions to Mineralogy and Petrology, 99, 226–237.

Lepvrier C., Maluski H., Nguyen Van Vuong, Roques D., Axente V., Rangin C., 1997. Indochina NW-trending shear zones within the Truong Son belt (Vietnam): 40Ar-39Ar Triassic ages and Cretaceous to Cenozoic overprints. Tectonophysics, 283, 105–127.

Lepvrier C., Maluski H., Vu V.T., Leyreloup A., Thi P.T., Vuong N.V., 2004. The Early Triassic Indosinian orogeny in Vietnam (Truong Son Belt and Kontum Massif): implications for the geodynamic evolution of Indochina. Tectonophysics, 393(1–4), 87–118.

Luong T.T.H., Nguyen V.V., Faure M., Wei L., Vu T.T., Tran T.T.N., Nguyen T.M.T., 2024. From rifting to Indosinian orogeny recorded in the Indochina from late Devonian to late Triassic: A review. Vietnam Journal of Earth Sciences, 47(1), 59–89.

Nagy E.A., Maluski H., Lepvrier C., Schärer U., Thi P.T., Leyreloup A., Thich, V.V., 2001. Geodynamic significance of the Kontum massif in central Vietnam: composite 40Ar/39Ar and U–Pb ages from Paleozoic to Triassic. The Journal of Geology, 109, 755–770.

Nakano N., Osanai Y., Owada M., Nam T.N., Tsunogae T., Toyoshima T., Binh P., 2004. Decompression process of mafic granulite from eclogite to granulite facies under ultrahigh-temperature condition in the Kontum massif, central Vietnam. Journal of Mineralogy and Petrological Sciences, 99, 242–256.

Nakano N., Osanai Y., Owada M., Nam T.N., Toyoshima T., Binh P., Tsunogae T., Kagami H., 2007. Geologic and metamorphic evolutions of the basement complexes in the Kontum Massif, central Vietnam. Gondwana Research, 12, 438–453.

Nakano N., Osanai Y., Owada M., Hayasaka Y., Nam T.N., 2009. Permo-Triassic Barrovian-type metamorphism in the ultrahigh-temperature Kontum Massif, central Vietnam: constraints on continental collision tectonics in Southeast Asia. The Island Arc, 18(1), 126–143.

Nakano N., Osanai Y., Owada M., Nam T.N., Charusiri P., Khamphavong K., 2013. Tectonic evolution of high-grade metamorphic terranes in central Vietnam: Constraints from large-scale monazite geochronology. Journal of Asian Earth Sciences, 73(5), 520–539.

Ngo X.T., Hung N.Q., Kim Y., Kwon S., Bui V.H., Tran T.H., Jang Y., Samuel V.O., 2024. Cambrian-Ordovician Arc-Related Magmatism in the Central Southeast Asian Continents and Its Significance on Early Palaeozoic Tectonics of the Indochina Block. Geological Journal, 60, 776–791.

Ngo X.T., Luong Q.K., Bui V.H., Tran T.H., Nguyen Q.H., Dinh T.T., 2025. Petrogenesis and geological significance of the early Paleozoic S-Type granitic mylonite in the Southwestern Kon Tum Massif, Central Vietnam. Vietnam Journal of Earth Sciences, 47(3), 1–18.

Nguyen D.N., Lo C.H., Usuki T., Iizuka Y., Pham B., 2023. P–T–t conditions of Early Palaeozoic low-P high-T granulitefacies metamorphism in the southern Truong Son Belt, Central Vietnam. Journal of Metamorphic Geology, 41, 1081–1117.

Nguyen H.T., Zong K., Liu Y., Yuan Y., Pham T.H., Le T.D., Pham M., 2021. Early Paleozoic arc magmatism and accretionary orogenesis in the Indochina Block, Southeast Asia. The Journal of Geology, 129(1), 33–48.

Nguyen Q.M., Feng Q., Zi J.-W., Zhao T., Tran H.T., Ngo T.X., Tran D.M., Nguyen H.Q., 2019. Cambrian intra-oceanic arc trondhjemite and tonalite in the Tam Ky-Phuoc Son Suture Zone, central Vietnam: implications for the early Paleozoic assembly of the Indochina Block. Gondwana Research, 70, 151–170.

Nguyen T.B.T., Pham T.T.H., Xin Q., Bui T.A., Nguyen T.X., Pham M., Ho T.T., 2024. 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. Minerals, 14, 569.

Nguyen V.T., 1995. Geological and Mineral resources map of Vietnam on scale 1:200.000. Huong Hoa-Hue-Da Nang sheet. Department of Geology and Minerals of Vietnam, Ha Noi.

Nguyen V.T., 1996a. Geological and Mineral resources map of Vietnam on scale 1:200.000. Ba Na sheet. Department of Geology and Minerals of Vietnam, Ha Noi.

Nguyen V.T., 1996b. Geological and Mineral Resources map of Vietnam on scale 1:200.000. Hoi An sheet. Department of Geology and Minerals of Viet Nam, Ha Noi.

Nguyen X.D., (Ed) 1996. Geological Maps on Scale 1:200.000 with Explanatory Note. Le Thuy-Quang Tri Sheet. Department of Geology of Vietnam, Hanoi.

Osanai Y., Nakano N., Owada M., Tran Ngoc Nam, Toyoshima T., Tsunogae T., Binh P., 2004. Permo-Triassic ultrahigh-temperature metamorphism in the Kontum massif, central Vietnam. Journal of Mineralogy and Petrological Sciences, 99, 225–241.

Osanai Y., Nakano N., Owada M., Tran N.N., Miyamoto T., Nguyen T.M., Nguyen V.N., Tran V.T., 2008. Collision zone metamorphism in Vietnam and adjacent Southeastern Asia: Proposition for Trans Vietnam Orogenic Belt. Journal of Mineralogical and Petrological Sciences, 103, 226–241.

Perchuk L.L., 1991. Derivation of a thermodynamically consistent set of geothermometers and geobarometers for metamorphic and magmatic rocks. In: Perchuk, L.L. (Ed.), Progress in Metamorphic and Magmatic Petrology: A Memorial Volume in Honor of D.S. Korzinskiy. Cambridge University Press, London, 93–111.

Pham T.H., Nguyen T.D., Nguyen T.B.T., Nguyen T.M., Pham M., 2016. U-Pb ages and Hf isotopic composition of zircon and bulk rock geochemistry of the Dai Loc granitoid complex in Kontum massif: Implications for Early Paleozoic crustal evolution in Central Vietnam. Journal of Mineralogical and Petrological Sciences, 111(5), 326–336.

Pham M., Pham T.H., Kawaguchi K., Nong T.Q.A., Le D.P., 2021. Geochemistry, zircon U-Pb geochronology and Sr-Nd-Hf isotopic composition of the Cha Val plutonic rocks in central Vietnam: Implications for Permian-Triassic Paleo-Tethys subduction-related magmatism. Vietnam Journal of Earth Sciences, 44(3), 301–326.

Sanematsu K., Murakami H., Duangsurigna S., Vilayhack S., Duncan R.A., Watanabe Y., 2011. 40Ar/39Ar ages of granitoids from the Truong Son fold belt and Kontum Massif in Laos. Journal of Mineralogical and Petrological Sciences, 106(1), 13–25.

Shang Z., Chen Y., 2022. Petrogenesis and Tectonic Implications of Early Paleozoic Magmatism in Awen Gold District, South Section of the Truong Son Orogenic Belt, Laos. Minerals, 12, 923.

Shi M.F., Lin F.C., Fan W.Y., Deng Q., Cong F., Tran M.D., Zhu H.P., Wang H., 2015. Zircon U-Pb ages and geochemistry of granitoids in the Truong Son terrane, Vietnam: Tectonic and metallogenic implications. Journal of Asian Earth Sciences, 101, 101–120.

Spear F.S., Cheney J.T., 1989. A petrogenetic grid for peliticschists in the system SiO2-Al2O3-FeO-MgO-K2O-H2O. Contributions to Mineralogy and Petrology, 101, 149–16.

Spear F.S., Kohn M.J., Cheney J.T., 1999. P-T paths from anatectic pelites. Contributions to Mineralogy and Petrology, 134, 17–32.

Thassanapak H., Udchachon M., Burrett C., 2018. Silurian radiolarians from the Sepon Mine, Truong Son Terrane, central Laos and their palaeogeographic and tectonic significance. Geological Magazine, 155(8), 1621–1640.

Thompson A.B., 1976. Mineral reactions in pelitic rocks; II, Calculation of some PTX (Fe-Mg) phase relations. American Journal of Science, 276, 425–454.

Thuc D.D., Trung H., 1995. Geology of Vietnam II. Magma. Department of Geology of Vietnam, Hanoi, p.359 (in Vietnamese).

Tran T.H., Tran T.A., Ngo T.P., Pham T.D., Tran V.A., 2005. Permian-Triassic magmatism of Vietnam and their potential of associated precious metals (Pt, Au), Proceedings of the scientific conference: 60th anniversary of Vietnam Geology, 63–79.

Tran T.H., Tran T.A., Ngo T.P., Pham T.D., Tran V.A., Izokh A.E., Borisenko A.S., Lan C.Y., Chung S.L., Lo C.H., 2008. Permo-Triassic intermediate-felsic magmatism of the Truong Son Belt, eastern margin of Indochina. Comptes Rendus Geoscience, 340 (2–3), 112–126.

Tran H.T., Zaw K., Halpin J.A., Manaka T., Meffre S., Lai C.K., Lee Y., Le H.V., Dinh S., 2014. The Tam Ky-Phuoc Son Shear Zone in central Vietnam: Tectonic and metallogenic implications. Gondwana Research, 26(1), 144–164.

Tran V.T., Vu K., 2011. Geology and earth resources of Viet Nam. Publish house for Science and Technology, 645p.

Tran T.V., Faure M., Nguyen V.V., Bui H.H., Fyhn M.B.W., Nguyen T.Q., Lepvrier C., Thomsen T.B., Tani K., Charusiri P., 2020. Neoproterozoic to Early Triassic tectono-stratigraphic evolution of Indochina and adjacent areas: A review with new data. Journal of Asian Earth Sciences, 191, 1–23.

Usuki T., Lan C.Y., Yeh M.W., Tran T.A., Iizuka Y., 2004, Metamorphic evolution in the northern Kontum Massif, central Vietnam. EOS Transactions, American Geophysical Union, 85(47), Fall Meeting Supplement, Abstract T11C-1273.

Usuki T., Lan C.Y., Yui T.F., Iizuka Y., Tich V.V., Anh T.T., Okamoto K., Wooden J.L., Liou J.G., 2009. Early Paleozoic medium-pressure metamorphism in central Vietnam: evidence from SHRIMP U-Pb zircon ages. Geoscience Journal, 13, 245–256.

Wang C., Liang X., Foster D.A., Fu J., Jiang Y., Dong C., Zhou Y., Wen S., Quynh P.V., 2016. Detrital zircon U-Pb geochronology, Lu-Hf isotopes and REE geochemistry constrains on the provenance and tectonic setting of Indochina Block in the Paleozoic. Tectonophysics, 677–678, 125–134.

Wang Y., Wang Y.K., Qian X., Zhang Y.Z., Gan C.S., Senebouttalath V., Wang Y., 2020. Early Paleozoic subduction in the Indochina interior: Revealed by Ordo-Silurian mafic-intermediate igneous rocks in South Laos. Lithos, 362–363, 105488.

Whitney D.L., Evans B.W., 2010. Abbreviations for names of rock-forming minerals. American Mineralogist, 95(1), 185–187.

Wu C.M., 2017. Calibration of the garnet-biotite-Al2SiO5-quartz geobarometer for metapelites. Journal of Metamorphic Geology, 35(9), 983–998.

Wu C.M., 2020. Calibration of the biotite-muscovite geobarometer for metapelitic assemblages devoid of garnet or plagioclase. Lithos, 372–373, 105668.

Wu C.M., Zhao G.C., 2006. Recalibration of the garnet-muscovite (GM) geothermometer and the garnet-muscovite-plagioclase-quartz (GMPQ) geobarometer for metapelitic assemblages. Journal of Petrology, 47, 2357–2368.

Wu C.M., Chen H.X., 2015. Revised Ti-in-biotite geothermometer for ilmenite-or rutile bearing crustal metapelites. Science Bulletin, 60, 116–121.