Neoproterozoic crustal growth of the Southern Yangtze Block

Geochemical and zircon U-Pb geochronological and Lu-Hf isotopic evidence of Neoproterozoic diorite from the Ailaoshan zone

Yongfeng Cai, Yuejun Wang, Peter A. Cawood, Yuzhi Zhang, Aimei Zhang

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Neoproterozoic felsic igneous rocks associated with mafic-ultramafic bodies along the margins of the Yangtze Block, South China, can be used to constrain the continental crustal growth and secular evolution of the region. LA-ICPMS zircon U-Pb dating of the Adebo quartz diorite pluton in the Ailaoshan tectonic zone on the southern margin of the Yangtze Block gives the Neoproterozoic age of 800±7Ma and e{open}Hf(t) values in the range of -1.03 to +3.75 with two-stage model age of 1.3-1.6Ga. The pluton is characterized by relatively low SiO2 (60.97-64.41wt.%) and total alkalis (K2O+Na2O, 7.35-9.14wt.%) and high Al2O3 content (16.98-18.21wt.%) with mg-number of 36-39. REE-normalized patterns show enrichment in LREE with (La/Yb)cn of 11.36-19.77 and Europium negative anomalies with Eu/Eu*=0.61-0.74. The samples are characterized by negative Nb-Ta ((Nb/La) n=0.18-0.35) and P, Ti, Sr anomalies and high Y concentrations (33.79-41.04ppm) and low Sr/Y ratios (5.65-10.16). Their isotopic composition are similar to those of the Neoproterozoic mafic igneous rocks in the Ailaoshan zone and the southwestern Yangtze Block, indicating that the quartz diorite was produced by partial melting of mafic lower crust. The diorite also shows the similar geochemical characteristics with adakitic rocks from thickened lower crust or amphibolite and eclogite experimental melts. In combination with their arc-related geochemical signatures and synchronous developed adakitic rocks in the region, the Adebo quartz diorite pluton might be produced in a subduction-related tectonic setting during Neoproterozoic crustal growth along the margins of Yangtze Block.

Original languageEnglish
Pages (from-to)137-149
Number of pages13
JournalPrecambrian Research
Volume266
DOIs
Publication statusPublished - 1 Sep 2015
Externally publishedYes

Keywords

  • ailaoshan zone
  • crustal growth
  • neoproterozoic
  • petrogenesis
  • quartz diorite
  • Yangtze block

Cite this

@article{e2659d27e6ec4eadb15ef64950e9c01f,
title = "Neoproterozoic crustal growth of the Southern Yangtze Block: Geochemical and zircon U-Pb geochronological and Lu-Hf isotopic evidence of Neoproterozoic diorite from the Ailaoshan zone",
abstract = "Neoproterozoic felsic igneous rocks associated with mafic-ultramafic bodies along the margins of the Yangtze Block, South China, can be used to constrain the continental crustal growth and secular evolution of the region. LA-ICPMS zircon U-Pb dating of the Adebo quartz diorite pluton in the Ailaoshan tectonic zone on the southern margin of the Yangtze Block gives the Neoproterozoic age of 800±7Ma and e{open}Hf(t) values in the range of -1.03 to +3.75 with two-stage model age of 1.3-1.6Ga. The pluton is characterized by relatively low SiO2 (60.97-64.41wt.{\%}) and total alkalis (K2O+Na2O, 7.35-9.14wt.{\%}) and high Al2O3 content (16.98-18.21wt.{\%}) with mg-number of 36-39. REE-normalized patterns show enrichment in LREE with (La/Yb)cn of 11.36-19.77 and Europium negative anomalies with Eu/Eu*=0.61-0.74. The samples are characterized by negative Nb-Ta ((Nb/La) n=0.18-0.35) and P, Ti, Sr anomalies and high Y concentrations (33.79-41.04ppm) and low Sr/Y ratios (5.65-10.16). Their isotopic composition are similar to those of the Neoproterozoic mafic igneous rocks in the Ailaoshan zone and the southwestern Yangtze Block, indicating that the quartz diorite was produced by partial melting of mafic lower crust. The diorite also shows the similar geochemical characteristics with adakitic rocks from thickened lower crust or amphibolite and eclogite experimental melts. In combination with their arc-related geochemical signatures and synchronous developed adakitic rocks in the region, the Adebo quartz diorite pluton might be produced in a subduction-related tectonic setting during Neoproterozoic crustal growth along the margins of Yangtze Block.",
keywords = "ailaoshan zone, crustal growth, neoproterozoic, petrogenesis, quartz diorite, Yangtze block",
author = "Yongfeng Cai and Yuejun Wang and Cawood, {Peter A.} and Yuzhi Zhang and Aimei Zhang",
year = "2015",
month = "9",
day = "1",
doi = "10.1016/j.precamres.2015.05.008",
language = "English",
volume = "266",
pages = "137--149",
journal = "Precambrian Research",
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}

Neoproterozoic crustal growth of the Southern Yangtze Block : Geochemical and zircon U-Pb geochronological and Lu-Hf isotopic evidence of Neoproterozoic diorite from the Ailaoshan zone. / Cai, Yongfeng; Wang, Yuejun; Cawood, Peter A.; Zhang, Yuzhi; Zhang, Aimei.

In: Precambrian Research, Vol. 266, 01.09.2015, p. 137-149.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Neoproterozoic crustal growth of the Southern Yangtze Block

T2 - Geochemical and zircon U-Pb geochronological and Lu-Hf isotopic evidence of Neoproterozoic diorite from the Ailaoshan zone

AU - Cai, Yongfeng

AU - Wang, Yuejun

AU - Cawood, Peter A.

AU - Zhang, Yuzhi

AU - Zhang, Aimei

PY - 2015/9/1

Y1 - 2015/9/1

N2 - Neoproterozoic felsic igneous rocks associated with mafic-ultramafic bodies along the margins of the Yangtze Block, South China, can be used to constrain the continental crustal growth and secular evolution of the region. LA-ICPMS zircon U-Pb dating of the Adebo quartz diorite pluton in the Ailaoshan tectonic zone on the southern margin of the Yangtze Block gives the Neoproterozoic age of 800±7Ma and e{open}Hf(t) values in the range of -1.03 to +3.75 with two-stage model age of 1.3-1.6Ga. The pluton is characterized by relatively low SiO2 (60.97-64.41wt.%) and total alkalis (K2O+Na2O, 7.35-9.14wt.%) and high Al2O3 content (16.98-18.21wt.%) with mg-number of 36-39. REE-normalized patterns show enrichment in LREE with (La/Yb)cn of 11.36-19.77 and Europium negative anomalies with Eu/Eu*=0.61-0.74. The samples are characterized by negative Nb-Ta ((Nb/La) n=0.18-0.35) and P, Ti, Sr anomalies and high Y concentrations (33.79-41.04ppm) and low Sr/Y ratios (5.65-10.16). Their isotopic composition are similar to those of the Neoproterozoic mafic igneous rocks in the Ailaoshan zone and the southwestern Yangtze Block, indicating that the quartz diorite was produced by partial melting of mafic lower crust. The diorite also shows the similar geochemical characteristics with adakitic rocks from thickened lower crust or amphibolite and eclogite experimental melts. In combination with their arc-related geochemical signatures and synchronous developed adakitic rocks in the region, the Adebo quartz diorite pluton might be produced in a subduction-related tectonic setting during Neoproterozoic crustal growth along the margins of Yangtze Block.

AB - Neoproterozoic felsic igneous rocks associated with mafic-ultramafic bodies along the margins of the Yangtze Block, South China, can be used to constrain the continental crustal growth and secular evolution of the region. LA-ICPMS zircon U-Pb dating of the Adebo quartz diorite pluton in the Ailaoshan tectonic zone on the southern margin of the Yangtze Block gives the Neoproterozoic age of 800±7Ma and e{open}Hf(t) values in the range of -1.03 to +3.75 with two-stage model age of 1.3-1.6Ga. The pluton is characterized by relatively low SiO2 (60.97-64.41wt.%) and total alkalis (K2O+Na2O, 7.35-9.14wt.%) and high Al2O3 content (16.98-18.21wt.%) with mg-number of 36-39. REE-normalized patterns show enrichment in LREE with (La/Yb)cn of 11.36-19.77 and Europium negative anomalies with Eu/Eu*=0.61-0.74. The samples are characterized by negative Nb-Ta ((Nb/La) n=0.18-0.35) and P, Ti, Sr anomalies and high Y concentrations (33.79-41.04ppm) and low Sr/Y ratios (5.65-10.16). Their isotopic composition are similar to those of the Neoproterozoic mafic igneous rocks in the Ailaoshan zone and the southwestern Yangtze Block, indicating that the quartz diorite was produced by partial melting of mafic lower crust. The diorite also shows the similar geochemical characteristics with adakitic rocks from thickened lower crust or amphibolite and eclogite experimental melts. In combination with their arc-related geochemical signatures and synchronous developed adakitic rocks in the region, the Adebo quartz diorite pluton might be produced in a subduction-related tectonic setting during Neoproterozoic crustal growth along the margins of Yangtze Block.

KW - ailaoshan zone

KW - crustal growth

KW - neoproterozoic

KW - petrogenesis

KW - quartz diorite

KW - Yangtze block

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U2 - 10.1016/j.precamres.2015.05.008

DO - 10.1016/j.precamres.2015.05.008

M3 - Article

VL - 266

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EP - 149

JO - Precambrian Research

JF - Precambrian Research

SN - 0301-9268

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