Formation of Cretaceous Cordilleran and post-orogenic granites and their microgranular enclaves from the Dalat zone, southern Vietnam: Tectonic implications for the evolution of Southeast Asia

J. Gregory Shellnutt; Ching Ying Lan; Trinh Van Long; Tadashi Usuki; Huai Jen Yang; Stanley A. Mertzman; Yoshi Iizuka; Sun Lin Chung; Kuo Lung Wang; Wen Yu Hsu

doi:10.1016/j.lithos.2013.09.016

Formation of Cretaceous Cordilleran and post-orogenic granites and their microgranular enclaves from the Dalat zone, southern Vietnam: Tectonic implications for the evolution of Southeast Asia

J. Gregory Shellnutt^*, Ching Ying Lan, Trinh Van Long, Tadashi Usuki, Huai Jen Yang, Stanley A. Mertzman, Yoshi Iizuka, Sun Lin Chung, Kuo Lung Wang, Wen Yu Hsu

^*Corresponding author for this work

Department of Earth Sciences (Include Institute of Marine Environmental Science and Technology)

Research output: Contribution to journal › Article › peer-review

89 Citations (Scopus)

Abstract

Cordilleran-type batholiths are useful in understanding the duration, cyclicity and tectonic evolution of continental margins. The Dalat zone of southern Vietnam preserves evidence of Late Mesozoic convergent zone magmatism superimposed on Precambrian rocks of the Indochina Block. The Dinhquan, Deoca and Ankroet plutons and their enclaves indicate that the Dalat zone transitioned from an active continental margin producing Cordilleran-type batholiths to highly extended crust producing within-plate plutons. The Deoca and Dinhquan plutons are compositionally similar to Cordilleran I-type granitic rocks and yield mean zircon U/Pb ages between 118±1.4Ma and 115±1.2Ma. Their Sr-Nd whole rock isotopes (I_Sr=0.7044 to 0.7062; εNd_(T)=-2.4 to +0.2) and zircon Hf isotopes (εHf_(T)=+8.2±1.2 and+6.4±0.9) indicate that they were derived by mixing between a mantle component and an enriched component (i.e. GLOSS). The Ankroet pluton is chemically similar to post-orogenic/within-plate granitic rocks and has a zircon U/Pb age of 87±1.6Ma. Geobarometric calculations indicate that amphibole within the Ankroet pluton crystallized at a depth of ~6kbar which is consistent with the somewhat more depleted Sr-Nd isotope (I_Sr=0.7017 to 0.7111; εNd_(T)=-2.8 to +0.6) and variable εHf_(T) compositions suggesting a stronger influence of crustal material in the parental magma. The compositional change of the Dalat zone granitic rocks during the middle to late Cretaceous indicates that the tectonic regime evolved from a continental arc environment to one of post-orogenic extension. The appearance of sporadic post-90Ma magmatism in the Dalat zone and along the eastern margin of Eurasian indicates that there was no subsequent orogenic event and the region was likely one of highly extended crust that facilitated the opening of the South China Sea during the latter half of the Cenozoic.

Original language	English
Pages (from-to)	229-241
Number of pages	13
Journal	Lithos
Volume	182-183
DOIs	https://doi.org/10.1016/j.lithos.2013.09.016
Publication status	Published - 2013 Dec

Keywords

Cretaceous
I-type granites
South Vietnam
Southeast Asia
Within-plate granites

ASJC Scopus subject areas

Geology
Geochemistry and Petrology

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10.1016/j.lithos.2013.09.016

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Shellnutt, J. G., Lan, C. Y., Van Long, T., Usuki, T., Yang, H. J., Mertzman, S. A., Iizuka, Y., Chung, S. L., Wang, K. L., & Hsu, W. Y. (2013). Formation of Cretaceous Cordilleran and post-orogenic granites and their microgranular enclaves from the Dalat zone, southern Vietnam: Tectonic implications for the evolution of Southeast Asia. Lithos, 182-183, 229-241. https://doi.org/10.1016/j.lithos.2013.09.016

Formation of Cretaceous Cordilleran and post-orogenic granites and their microgranular enclaves from the Dalat zone, southern Vietnam: Tectonic implications for the evolution of Southeast Asia. / Shellnutt, J. Gregory; Lan, Ching Ying; Van Long, Trinh et al.
In: Lithos, Vol. 182-183, 12.2013, p. 229-241.

Research output: Contribution to journal › Article › peer-review

Shellnutt, JG, Lan, CY, Van Long, T, Usuki, T, Yang, HJ, Mertzman, SA, Iizuka, Y, Chung, SL, Wang, KL & Hsu, WY 2013, 'Formation of Cretaceous Cordilleran and post-orogenic granites and their microgranular enclaves from the Dalat zone, southern Vietnam: Tectonic implications for the evolution of Southeast Asia', Lithos, vol. 182-183, pp. 229-241. https://doi.org/10.1016/j.lithos.2013.09.016

@article{81d5235da4db42df8265a850cb391b32,

title = "Formation of Cretaceous Cordilleran and post-orogenic granites and their microgranular enclaves from the Dalat zone, southern Vietnam: Tectonic implications for the evolution of Southeast Asia",

abstract = "Cordilleran-type batholiths are useful in understanding the duration, cyclicity and tectonic evolution of continental margins. The Dalat zone of southern Vietnam preserves evidence of Late Mesozoic convergent zone magmatism superimposed on Precambrian rocks of the Indochina Block. The Dinhquan, Deoca and Ankroet plutons and their enclaves indicate that the Dalat zone transitioned from an active continental margin producing Cordilleran-type batholiths to highly extended crust producing within-plate plutons. The Deoca and Dinhquan plutons are compositionally similar to Cordilleran I-type granitic rocks and yield mean zircon U/Pb ages between 118±1.4Ma and 115±1.2Ma. Their Sr-Nd whole rock isotopes (ISr=0.7044 to 0.7062; εNd(T)=-2.4 to +0.2) and zircon Hf isotopes (εHf(T)=+8.2±1.2 and+6.4±0.9) indicate that they were derived by mixing between a mantle component and an enriched component (i.e. GLOSS). The Ankroet pluton is chemically similar to post-orogenic/within-plate granitic rocks and has a zircon U/Pb age of 87±1.6Ma. Geobarometric calculations indicate that amphibole within the Ankroet pluton crystallized at a depth of ~6kbar which is consistent with the somewhat more depleted Sr-Nd isotope (ISr=0.7017 to 0.7111; εNd(T)=-2.8 to +0.6) and variable εHf(T) compositions suggesting a stronger influence of crustal material in the parental magma. The compositional change of the Dalat zone granitic rocks during the middle to late Cretaceous indicates that the tectonic regime evolved from a continental arc environment to one of post-orogenic extension. The appearance of sporadic post-90Ma magmatism in the Dalat zone and along the eastern margin of Eurasian indicates that there was no subsequent orogenic event and the region was likely one of highly extended crust that facilitated the opening of the South China Sea during the latter half of the Cenozoic.",

keywords = "Cretaceous, I-type granites, South Vietnam, Southeast Asia, Within-plate granites",

author = "Shellnutt, {J. Gregory} and Lan, {Ching Ying} and {Van Long}, Trinh and Tadashi Usuki and Yang, {Huai Jen} and Mertzman, {Stanley A.} and Yoshi Iizuka and Chung, {Sun Lin} and Wang, {Kuo Lung} and Hsu, {Wen Yu}",

note = "Funding Information: We would like to thank Antonio Castro, an anonymous review and Nelson Eby for additional comments and suggestions which greatly improved the manuscript. Additional thanks to Mary Yeh and Tony Lee for their insight on the tectonics of SE Asia. Tran Tuan-Anh and Tran Trong-Hoa of Institute of Geological Sciences, Viet Nam are thanked for assistance with field work. This study was supported by Academia Sinica and National Science Council of the Republic of China, under grants of NSC100-2116-M-003-006 to JGS and NSC 93-2116-M-001-015 to CYL. This paper is Contribution IESEP XXX of the Institute of Earth Sciences, Academia Sinica.",

year = "2013",

month = dec,

doi = "10.1016/j.lithos.2013.09.016",

language = "English",

volume = "182-183",

pages = "229--241",

journal = "Lithos",

issn = "0024-4937",

publisher = "Elsevier BV",

}

TY - JOUR

T1 - Formation of Cretaceous Cordilleran and post-orogenic granites and their microgranular enclaves from the Dalat zone, southern Vietnam

T2 - Tectonic implications for the evolution of Southeast Asia

AU - Shellnutt, J. Gregory

AU - Lan, Ching Ying

AU - Van Long, Trinh

AU - Usuki, Tadashi

AU - Yang, Huai Jen

AU - Mertzman, Stanley A.

AU - Iizuka, Yoshi

AU - Chung, Sun Lin

AU - Wang, Kuo Lung

AU - Hsu, Wen Yu

N1 - Funding Information: We would like to thank Antonio Castro, an anonymous review and Nelson Eby for additional comments and suggestions which greatly improved the manuscript. Additional thanks to Mary Yeh and Tony Lee for their insight on the tectonics of SE Asia. Tran Tuan-Anh and Tran Trong-Hoa of Institute of Geological Sciences, Viet Nam are thanked for assistance with field work. This study was supported by Academia Sinica and National Science Council of the Republic of China, under grants of NSC100-2116-M-003-006 to JGS and NSC 93-2116-M-001-015 to CYL. This paper is Contribution IESEP XXX of the Institute of Earth Sciences, Academia Sinica.

PY - 2013/12

Y1 - 2013/12

N2 - Cordilleran-type batholiths are useful in understanding the duration, cyclicity and tectonic evolution of continental margins. The Dalat zone of southern Vietnam preserves evidence of Late Mesozoic convergent zone magmatism superimposed on Precambrian rocks of the Indochina Block. The Dinhquan, Deoca and Ankroet plutons and their enclaves indicate that the Dalat zone transitioned from an active continental margin producing Cordilleran-type batholiths to highly extended crust producing within-plate plutons. The Deoca and Dinhquan plutons are compositionally similar to Cordilleran I-type granitic rocks and yield mean zircon U/Pb ages between 118±1.4Ma and 115±1.2Ma. Their Sr-Nd whole rock isotopes (ISr=0.7044 to 0.7062; εNd(T)=-2.4 to +0.2) and zircon Hf isotopes (εHf(T)=+8.2±1.2 and+6.4±0.9) indicate that they were derived by mixing between a mantle component and an enriched component (i.e. GLOSS). The Ankroet pluton is chemically similar to post-orogenic/within-plate granitic rocks and has a zircon U/Pb age of 87±1.6Ma. Geobarometric calculations indicate that amphibole within the Ankroet pluton crystallized at a depth of ~6kbar which is consistent with the somewhat more depleted Sr-Nd isotope (ISr=0.7017 to 0.7111; εNd(T)=-2.8 to +0.6) and variable εHf(T) compositions suggesting a stronger influence of crustal material in the parental magma. The compositional change of the Dalat zone granitic rocks during the middle to late Cretaceous indicates that the tectonic regime evolved from a continental arc environment to one of post-orogenic extension. The appearance of sporadic post-90Ma magmatism in the Dalat zone and along the eastern margin of Eurasian indicates that there was no subsequent orogenic event and the region was likely one of highly extended crust that facilitated the opening of the South China Sea during the latter half of the Cenozoic.

AB - Cordilleran-type batholiths are useful in understanding the duration, cyclicity and tectonic evolution of continental margins. The Dalat zone of southern Vietnam preserves evidence of Late Mesozoic convergent zone magmatism superimposed on Precambrian rocks of the Indochina Block. The Dinhquan, Deoca and Ankroet plutons and their enclaves indicate that the Dalat zone transitioned from an active continental margin producing Cordilleran-type batholiths to highly extended crust producing within-plate plutons. The Deoca and Dinhquan plutons are compositionally similar to Cordilleran I-type granitic rocks and yield mean zircon U/Pb ages between 118±1.4Ma and 115±1.2Ma. Their Sr-Nd whole rock isotopes (ISr=0.7044 to 0.7062; εNd(T)=-2.4 to +0.2) and zircon Hf isotopes (εHf(T)=+8.2±1.2 and+6.4±0.9) indicate that they were derived by mixing between a mantle component and an enriched component (i.e. GLOSS). The Ankroet pluton is chemically similar to post-orogenic/within-plate granitic rocks and has a zircon U/Pb age of 87±1.6Ma. Geobarometric calculations indicate that amphibole within the Ankroet pluton crystallized at a depth of ~6kbar which is consistent with the somewhat more depleted Sr-Nd isotope (ISr=0.7017 to 0.7111; εNd(T)=-2.8 to +0.6) and variable εHf(T) compositions suggesting a stronger influence of crustal material in the parental magma. The compositional change of the Dalat zone granitic rocks during the middle to late Cretaceous indicates that the tectonic regime evolved from a continental arc environment to one of post-orogenic extension. The appearance of sporadic post-90Ma magmatism in the Dalat zone and along the eastern margin of Eurasian indicates that there was no subsequent orogenic event and the region was likely one of highly extended crust that facilitated the opening of the South China Sea during the latter half of the Cenozoic.

KW - Cretaceous

KW - I-type granites

KW - South Vietnam

KW - Southeast Asia

KW - Within-plate granites

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Formation of Cretaceous Cordilleran and post-orogenic granites and their microgranular enclaves from the Dalat zone, southern Vietnam: Tectonic implications for the evolution of Southeast Asia

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