Carboniferous-Permian extensive magmatism in the West Junggar, Xinjiang, northwestern China: Its geochemistry, geochronology, and petrogenesis

R. Gao, L. Xiao, Franco Pirajno, G. Wang, X. He, G. Yang, S. Yan

Research output: Contribution to journalArticle

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Abstract

Located between the Tarim, Kazakhstan, and Siberian plates, the West Junggar terrane is a key component of the Paleozoic Central Asian Orogenic Belt (CAOB) with widespread late Paleozoic igneous rocks. In this paper, we report petrological, geochronological, and geochemical data for selected granitoids from the West Junggar. Based on geochronology, the I-type and A-type granites were formed predominantly at 347.9-319.0Ma and at 321.4-290Ma respectively. The early-stage I-type granites are characterized by low SiO2, Na2O, and K2O contents with Na2O/K2O ratios>1 and are metaluminous to weakly-peraluminous. They are enriched in large ion lithophile elements (LILE) and in Sr but depleted in high field strength elements (HFSE), with (87Sr/86Sr)i ratios of 0.7028-0.7044 and εNd(t) values varying from +5.74 to +7.76. The late-stage I-type granites are characterized by low contents of Si2O and K2O and relatively high contents of FeO, MgO, and Na2O with Na2O/K2O ratios >1, and are metaluminous to weakly-peraluminous. They are also enriched in LILE and depleted in HFSE with Eu anomalies, (87Sr/86Sr)i ratios of 0.703-0.704, and εNd(t) values varying from +5.20 to +8.00. The A-type granites have high SiO2 contents, high K calc-alkaline-shoshonitic affinities, positive εNd(t) values (5.76-7.77), and low initial 87Sr/86Sr ratios (0.7017-0.7045). Along with reported Sr-Nd isotopic data and regional geologic evidence the Early Carboniferous I-type granites are interpreted as products of partial melting of trapped oceanic crust triggered by underplated mantle wedge-derived basaltic magma; the Late Carboniferous-Early Permian I-type granites as derivatives of partially melted trapped oceanic crust; and the A-type granites as resulting from partial melting of trapped juvenile oceanic crust in an extensional regime. The A-type granitoids with high positive εNd(t) values and high Zr-saturation temperatures could be genetically related to a mantle plume or a regional-scale mantle upwelling in the CAOB. © 2014 Elsevier B.V.
Original languageEnglish
Pages (from-to)125-143
JournalLithos
Volume204
DOIs
Publication statusPublished - 1 Sep 2014

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Geochronology
Geochemistry
petrogenesis
geochronology
oceanic crust
magmatism
Permian
geochemistry
orogenic belt
partial melting
Paleozoic
Heavy ions
Melting
ion
mantle plume
Igneous rocks
igneous rock
terrane
magma
saturation

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@article{b3df9536c9a845298af6dfb12e5fce63,
title = "Carboniferous-Permian extensive magmatism in the West Junggar, Xinjiang, northwestern China: Its geochemistry, geochronology, and petrogenesis",
abstract = "Located between the Tarim, Kazakhstan, and Siberian plates, the West Junggar terrane is a key component of the Paleozoic Central Asian Orogenic Belt (CAOB) with widespread late Paleozoic igneous rocks. In this paper, we report petrological, geochronological, and geochemical data for selected granitoids from the West Junggar. Based on geochronology, the I-type and A-type granites were formed predominantly at 347.9-319.0Ma and at 321.4-290Ma respectively. The early-stage I-type granites are characterized by low SiO2, Na2O, and K2O contents with Na2O/K2O ratios>1 and are metaluminous to weakly-peraluminous. They are enriched in large ion lithophile elements (LILE) and in Sr but depleted in high field strength elements (HFSE), with (87Sr/86Sr)i ratios of 0.7028-0.7044 and εNd(t) values varying from +5.74 to +7.76. The late-stage I-type granites are characterized by low contents of Si2O and K2O and relatively high contents of FeO, MgO, and Na2O with Na2O/K2O ratios >1, and are metaluminous to weakly-peraluminous. They are also enriched in LILE and depleted in HFSE with Eu anomalies, (87Sr/86Sr)i ratios of 0.703-0.704, and εNd(t) values varying from +5.20 to +8.00. The A-type granites have high SiO2 contents, high K calc-alkaline-shoshonitic affinities, positive εNd(t) values (5.76-7.77), and low initial 87Sr/86Sr ratios (0.7017-0.7045). Along with reported Sr-Nd isotopic data and regional geologic evidence the Early Carboniferous I-type granites are interpreted as products of partial melting of trapped oceanic crust triggered by underplated mantle wedge-derived basaltic magma; the Late Carboniferous-Early Permian I-type granites as derivatives of partially melted trapped oceanic crust; and the A-type granites as resulting from partial melting of trapped juvenile oceanic crust in an extensional regime. The A-type granitoids with high positive εNd(t) values and high Zr-saturation temperatures could be genetically related to a mantle plume or a regional-scale mantle upwelling in the CAOB. {\circledC} 2014 Elsevier B.V.",
author = "R. Gao and L. Xiao and Franco Pirajno and G. Wang and X. He and G. Yang and S. Yan",
year = "2014",
month = "9",
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language = "English",
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Carboniferous-Permian extensive magmatism in the West Junggar, Xinjiang, northwestern China: Its geochemistry, geochronology, and petrogenesis. / Gao, R.; Xiao, L.; Pirajno, Franco; Wang, G.; He, X.; Yang, G.; Yan, S.

In: Lithos, Vol. 204, 01.09.2014, p. 125-143.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Carboniferous-Permian extensive magmatism in the West Junggar, Xinjiang, northwestern China: Its geochemistry, geochronology, and petrogenesis

AU - Gao, R.

AU - Xiao, L.

AU - Pirajno, Franco

AU - Wang, G.

AU - He, X.

AU - Yang, G.

AU - Yan, S.

PY - 2014/9/1

Y1 - 2014/9/1

N2 - Located between the Tarim, Kazakhstan, and Siberian plates, the West Junggar terrane is a key component of the Paleozoic Central Asian Orogenic Belt (CAOB) with widespread late Paleozoic igneous rocks. In this paper, we report petrological, geochronological, and geochemical data for selected granitoids from the West Junggar. Based on geochronology, the I-type and A-type granites were formed predominantly at 347.9-319.0Ma and at 321.4-290Ma respectively. The early-stage I-type granites are characterized by low SiO2, Na2O, and K2O contents with Na2O/K2O ratios>1 and are metaluminous to weakly-peraluminous. They are enriched in large ion lithophile elements (LILE) and in Sr but depleted in high field strength elements (HFSE), with (87Sr/86Sr)i ratios of 0.7028-0.7044 and εNd(t) values varying from +5.74 to +7.76. The late-stage I-type granites are characterized by low contents of Si2O and K2O and relatively high contents of FeO, MgO, and Na2O with Na2O/K2O ratios >1, and are metaluminous to weakly-peraluminous. They are also enriched in LILE and depleted in HFSE with Eu anomalies, (87Sr/86Sr)i ratios of 0.703-0.704, and εNd(t) values varying from +5.20 to +8.00. The A-type granites have high SiO2 contents, high K calc-alkaline-shoshonitic affinities, positive εNd(t) values (5.76-7.77), and low initial 87Sr/86Sr ratios (0.7017-0.7045). Along with reported Sr-Nd isotopic data and regional geologic evidence the Early Carboniferous I-type granites are interpreted as products of partial melting of trapped oceanic crust triggered by underplated mantle wedge-derived basaltic magma; the Late Carboniferous-Early Permian I-type granites as derivatives of partially melted trapped oceanic crust; and the A-type granites as resulting from partial melting of trapped juvenile oceanic crust in an extensional regime. The A-type granitoids with high positive εNd(t) values and high Zr-saturation temperatures could be genetically related to a mantle plume or a regional-scale mantle upwelling in the CAOB. © 2014 Elsevier B.V.

AB - Located between the Tarim, Kazakhstan, and Siberian plates, the West Junggar terrane is a key component of the Paleozoic Central Asian Orogenic Belt (CAOB) with widespread late Paleozoic igneous rocks. In this paper, we report petrological, geochronological, and geochemical data for selected granitoids from the West Junggar. Based on geochronology, the I-type and A-type granites were formed predominantly at 347.9-319.0Ma and at 321.4-290Ma respectively. The early-stage I-type granites are characterized by low SiO2, Na2O, and K2O contents with Na2O/K2O ratios>1 and are metaluminous to weakly-peraluminous. They are enriched in large ion lithophile elements (LILE) and in Sr but depleted in high field strength elements (HFSE), with (87Sr/86Sr)i ratios of 0.7028-0.7044 and εNd(t) values varying from +5.74 to +7.76. The late-stage I-type granites are characterized by low contents of Si2O and K2O and relatively high contents of FeO, MgO, and Na2O with Na2O/K2O ratios >1, and are metaluminous to weakly-peraluminous. They are also enriched in LILE and depleted in HFSE with Eu anomalies, (87Sr/86Sr)i ratios of 0.703-0.704, and εNd(t) values varying from +5.20 to +8.00. The A-type granites have high SiO2 contents, high K calc-alkaline-shoshonitic affinities, positive εNd(t) values (5.76-7.77), and low initial 87Sr/86Sr ratios (0.7017-0.7045). Along with reported Sr-Nd isotopic data and regional geologic evidence the Early Carboniferous I-type granites are interpreted as products of partial melting of trapped oceanic crust triggered by underplated mantle wedge-derived basaltic magma; the Late Carboniferous-Early Permian I-type granites as derivatives of partially melted trapped oceanic crust; and the A-type granites as resulting from partial melting of trapped juvenile oceanic crust in an extensional regime. The A-type granitoids with high positive εNd(t) values and high Zr-saturation temperatures could be genetically related to a mantle plume or a regional-scale mantle upwelling in the CAOB. © 2014 Elsevier B.V.

U2 - 10.1016/j.lithos.2014.05.028

DO - 10.1016/j.lithos.2014.05.028

M3 - Article

VL - 204

SP - 125

EP - 143

JO - Lithos

JF - Lithos

SN - 0024-4937

ER -