Evolution history of the Neoproterozoic eclogite-bearing complex of the Muya dome (Central Asian Orogenic Belt): Constraints from zircon U-Pb age, Hf and whole-rock Nd isotopes

V. S. Shatsky; V. G. Malkovets; E. A. Belousova; S. Yu Skuzovatov

doi:10.1016/j.precamres.2015.01.013

Evolution history of the Neoproterozoic eclogite-bearing complex of the Muya dome (Central Asian Orogenic Belt): Constraints from zircon U-Pb age, Hf and whole-rock Nd isotopes

V. S. Shatsky, V. G. Malkovets, E. A. Belousova, S. Yu Skuzovatov

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

11 Citations (Scopus)

Abstract

U-Pb dating and Hf-isotope analysis of zircons and whole-rock Nd-isotope analyses were carried out on country rocks of the eclogite-gneiss complex of the North Muya dome in the Anamakit-Muya zone of the Baikal Muya accretionary fold belt. Zircons from garnet-biotite gneisses (Qtz+Kfsp+Pl+Bt+Grt) and garnet-biotite-muscovite schist (Pl+Kfsp+Bt+Mu+Grt+Qtz) were dated using the LA-ICP-MS technique. Based on U-Pb isotope data and CL images zircon grains were divided into three groups: detrital, magmatic and metamorphic zircons. Metamorphic zircons display no zoning or the cloudy zoning. The grains morphology together with the well-developed oscillatory zoning clearly identifies the igneous origin of magmatic zircons. The metamorphic zircons (ages 576-680Ma) have Th/U ratios varying from 0.271 to 0.004, whereas the ratio in magmatic zircons ranges from 0.779 to 0.11. Magmatic zircons from granite-gneisses of the North Muya dome exhibit a relatively narrow spread in the crystallization age with the major peak at ca 764Ma. Younger ages are interpreted as due to the partial resetting of U-Pb system during the subsequent metamorphic evolution. Detrital zircons from two-mica schist sample Mu-93-10 give ages of 1.88-2.66Ga. The oldest detrital zircon from this sample plots near concordia and has a ²⁰⁷Pb/²⁰⁶Pb age of 3.2Ga. Zircons from this sample are characterized by the widest scatter of e_Hf(t) values (from +13.9 to -15.3) and T^C_DM model ages (0.82-3.86Ga). Zircons from other samples have a much narrower ranges of e_Hf(t) (+11.6 to -0.7) and T^C_DM (0.85-1.52Ga). The involvement of older crustal material is also evident from the whole-rock Nd isotopic compositions. The gneisses and schists exhibit a range of Nd isotopic compositions with e_Nd(t) values ranging from -3.5 to +3.6 and t_Nd(DM) from 1.64 to 1.09Ga. The integration of the Hf-isotope data with the age spectra provides with the first evidence for the existence of Mesoarchean crust in the Baykal-Muya sector of the Central Asian Orogenic Belt.

Original language	English
Pages (from-to)	1-11
Number of pages	11
Journal	Precambrian Research
Volume	261
DOIs	https://doi.org/10.1016/j.precamres.2015.01.013
Publication status	Published - May 1 2015

Keywords

Central Asian Orogenic Belt
Continental subduction
Hf isotopes
U-Pb dating
Zircon

ASJC Scopus subject areas

Geology
Geochemistry and Petrology

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10.1016/j.precamres.2015.01.013

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@article{42b3a34c90d94979947b67fef534334c,

title = "Evolution history of the Neoproterozoic eclogite-bearing complex of the Muya dome (Central Asian Orogenic Belt): Constraints from zircon U-Pb age, Hf and whole-rock Nd isotopes",

abstract = "U-Pb dating and Hf-isotope analysis of zircons and whole-rock Nd-isotope analyses were carried out on country rocks of the eclogite-gneiss complex of the North Muya dome in the Anamakit-Muya zone of the Baikal Muya accretionary fold belt. Zircons from garnet-biotite gneisses (Qtz+Kfsp+Pl+Bt+Grt) and garnet-biotite-muscovite schist (Pl+Kfsp+Bt+Mu+Grt+Qtz) were dated using the LA-ICP-MS technique. Based on U-Pb isotope data and CL images zircon grains were divided into three groups: detrital, magmatic and metamorphic zircons. Metamorphic zircons display no zoning or the cloudy zoning. The grains morphology together with the well-developed oscillatory zoning clearly identifies the igneous origin of magmatic zircons. The metamorphic zircons (ages 576-680Ma) have Th/U ratios varying from 0.271 to 0.004, whereas the ratio in magmatic zircons ranges from 0.779 to 0.11. Magmatic zircons from granite-gneisses of the North Muya dome exhibit a relatively narrow spread in the crystallization age with the major peak at ca 764Ma. Younger ages are interpreted as due to the partial resetting of U-Pb system during the subsequent metamorphic evolution. Detrital zircons from two-mica schist sample Mu-93-10 give ages of 1.88-2.66Ga. The oldest detrital zircon from this sample plots near concordia and has a 207Pb/206Pb age of 3.2Ga. Zircons from this sample are characterized by the widest scatter of eHf(t) values (from +13.9 to -15.3) and TCDM model ages (0.82-3.86Ga). Zircons from other samples have a much narrower ranges of eHf(t) (+11.6 to -0.7) and TCDM (0.85-1.52Ga). The involvement of older crustal material is also evident from the whole-rock Nd isotopic compositions. The gneisses and schists exhibit a range of Nd isotopic compositions with eNd(t) values ranging from -3.5 to +3.6 and tNd(DM) from 1.64 to 1.09Ga. The integration of the Hf-isotope data with the age spectra provides with the first evidence for the existence of Mesoarchean crust in the Baykal-Muya sector of the Central Asian Orogenic Belt.",

keywords = "Central Asian Orogenic Belt, Continental subduction, Hf isotopes, U-Pb dating, Zircon",

author = "Shatsky, {V. S.} and Malkovets, {V. G.} and Belousova, {E. A.} and Skuzovatov, {S. Yu}",

note = "Funding Information: We are grateful to W.L. Griffin for productive discussions that significantly improved the quality of the manuscript. Vladislav Shatsky and Sergei Skuzovatov were partially supported by the Siberian Branch of the Russian Academy of Sciences (integration project No. 49) and Russian Foundation for Basic Research (Grant No. 13-05-00261 ). Vladimir Malkovets was partially supported by Russian Foundation for Basic Research (grants No. 12-05-33035 , 13-05-01051 and 15-05-05615 ). Elena Belousova acknowledges ARC support through FT110100685. This study was funded by Australian Research Council (ARC) grants and funding to the ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS), and used instrumentation funded by the Australian Research Council, ARC LIEF grants, NCRIS, DEST SII grants, Macquarie University and industry sources. This is contribution 583 from the ARC Centre of Excellence for Core to Crust Fluid Systems (http://www.ccfs.mq.edu.au) and 989 in the GEMOC Key Centre (http://www.gemoc.mq.edu.au). We thank two anonymous referees for constructive and thoughtful comments. Our great thanks to Anastasia Gibsher for technical help with portions of the manuscript. We thank Prof. W.L. Griffin for editing the English. Publisher Copyright: {\textcopyright} 2015 Elsevier B.V. Copyright: Copyright 2015 Elsevier B.V., All rights reserved.",

year = "2015",

month = may,

day = "1",

doi = "10.1016/j.precamres.2015.01.013",

language = "English",

volume = "261",

pages = "1--11",

journal = "Precambrian Research",

issn = "0301-9268",

publisher = "Elsevier",

}

TY - JOUR

T1 - Evolution history of the Neoproterozoic eclogite-bearing complex of the Muya dome (Central Asian Orogenic Belt)

T2 - Constraints from zircon U-Pb age, Hf and whole-rock Nd isotopes

AU - Shatsky, V. S.

AU - Malkovets, V. G.

AU - Belousova, E. A.

AU - Skuzovatov, S. Yu

N1 - Funding Information: We are grateful to W.L. Griffin for productive discussions that significantly improved the quality of the manuscript. Vladislav Shatsky and Sergei Skuzovatov were partially supported by the Siberian Branch of the Russian Academy of Sciences (integration project No. 49) and Russian Foundation for Basic Research (Grant No. 13-05-00261 ). Vladimir Malkovets was partially supported by Russian Foundation for Basic Research (grants No. 12-05-33035 , 13-05-01051 and 15-05-05615 ). Elena Belousova acknowledges ARC support through FT110100685. This study was funded by Australian Research Council (ARC) grants and funding to the ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS), and used instrumentation funded by the Australian Research Council, ARC LIEF grants, NCRIS, DEST SII grants, Macquarie University and industry sources. This is contribution 583 from the ARC Centre of Excellence for Core to Crust Fluid Systems (http://www.ccfs.mq.edu.au) and 989 in the GEMOC Key Centre (http://www.gemoc.mq.edu.au). We thank two anonymous referees for constructive and thoughtful comments. Our great thanks to Anastasia Gibsher for technical help with portions of the manuscript. We thank Prof. W.L. Griffin for editing the English. Publisher Copyright: © 2015 Elsevier B.V. Copyright: Copyright 2015 Elsevier B.V., All rights reserved.

PY - 2015/5/1

Y1 - 2015/5/1

N2 - U-Pb dating and Hf-isotope analysis of zircons and whole-rock Nd-isotope analyses were carried out on country rocks of the eclogite-gneiss complex of the North Muya dome in the Anamakit-Muya zone of the Baikal Muya accretionary fold belt. Zircons from garnet-biotite gneisses (Qtz+Kfsp+Pl+Bt+Grt) and garnet-biotite-muscovite schist (Pl+Kfsp+Bt+Mu+Grt+Qtz) were dated using the LA-ICP-MS technique. Based on U-Pb isotope data and CL images zircon grains were divided into three groups: detrital, magmatic and metamorphic zircons. Metamorphic zircons display no zoning or the cloudy zoning. The grains morphology together with the well-developed oscillatory zoning clearly identifies the igneous origin of magmatic zircons. The metamorphic zircons (ages 576-680Ma) have Th/U ratios varying from 0.271 to 0.004, whereas the ratio in magmatic zircons ranges from 0.779 to 0.11. Magmatic zircons from granite-gneisses of the North Muya dome exhibit a relatively narrow spread in the crystallization age with the major peak at ca 764Ma. Younger ages are interpreted as due to the partial resetting of U-Pb system during the subsequent metamorphic evolution. Detrital zircons from two-mica schist sample Mu-93-10 give ages of 1.88-2.66Ga. The oldest detrital zircon from this sample plots near concordia and has a 207Pb/206Pb age of 3.2Ga. Zircons from this sample are characterized by the widest scatter of eHf(t) values (from +13.9 to -15.3) and TCDM model ages (0.82-3.86Ga). Zircons from other samples have a much narrower ranges of eHf(t) (+11.6 to -0.7) and TCDM (0.85-1.52Ga). The involvement of older crustal material is also evident from the whole-rock Nd isotopic compositions. The gneisses and schists exhibit a range of Nd isotopic compositions with eNd(t) values ranging from -3.5 to +3.6 and tNd(DM) from 1.64 to 1.09Ga. The integration of the Hf-isotope data with the age spectra provides with the first evidence for the existence of Mesoarchean crust in the Baykal-Muya sector of the Central Asian Orogenic Belt.

AB - U-Pb dating and Hf-isotope analysis of zircons and whole-rock Nd-isotope analyses were carried out on country rocks of the eclogite-gneiss complex of the North Muya dome in the Anamakit-Muya zone of the Baikal Muya accretionary fold belt. Zircons from garnet-biotite gneisses (Qtz+Kfsp+Pl+Bt+Grt) and garnet-biotite-muscovite schist (Pl+Kfsp+Bt+Mu+Grt+Qtz) were dated using the LA-ICP-MS technique. Based on U-Pb isotope data and CL images zircon grains were divided into three groups: detrital, magmatic and metamorphic zircons. Metamorphic zircons display no zoning or the cloudy zoning. The grains morphology together with the well-developed oscillatory zoning clearly identifies the igneous origin of magmatic zircons. The metamorphic zircons (ages 576-680Ma) have Th/U ratios varying from 0.271 to 0.004, whereas the ratio in magmatic zircons ranges from 0.779 to 0.11. Magmatic zircons from granite-gneisses of the North Muya dome exhibit a relatively narrow spread in the crystallization age with the major peak at ca 764Ma. Younger ages are interpreted as due to the partial resetting of U-Pb system during the subsequent metamorphic evolution. Detrital zircons from two-mica schist sample Mu-93-10 give ages of 1.88-2.66Ga. The oldest detrital zircon from this sample plots near concordia and has a 207Pb/206Pb age of 3.2Ga. Zircons from this sample are characterized by the widest scatter of eHf(t) values (from +13.9 to -15.3) and TCDM model ages (0.82-3.86Ga). Zircons from other samples have a much narrower ranges of eHf(t) (+11.6 to -0.7) and TCDM (0.85-1.52Ga). The involvement of older crustal material is also evident from the whole-rock Nd isotopic compositions. The gneisses and schists exhibit a range of Nd isotopic compositions with eNd(t) values ranging from -3.5 to +3.6 and tNd(DM) from 1.64 to 1.09Ga. The integration of the Hf-isotope data with the age spectra provides with the first evidence for the existence of Mesoarchean crust in the Baykal-Muya sector of the Central Asian Orogenic Belt.

KW - Central Asian Orogenic Belt

KW - Continental subduction

KW - Hf isotopes

KW - U-Pb dating

KW - Zircon

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Evolution history of the Neoproterozoic eclogite-bearing complex of the Muya dome (Central Asian Orogenic Belt): Constraints from zircon U-Pb age, Hf and whole-rock Nd isotopes

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