Palaeoproterozoic ancestry of Pan-African high-grade granitoids in southernmost India : Implications for Gondwana reconstructions

A. KRÖNER*, M. SANTOSH, E. HEGNER, E. SHAJI, H. GENG, J. WONG, H. XIE, Y. WAN, C. K. SHANG, D. LIU, M. SUN, V. NANDA-KUMAR

*Corresponding author for this work

Research output: Journal PublicationsReview article

33 Citations (Scopus)

Abstract

SHRIMP dating of magmatic zircons from granitoid gneisses and charnockites of the Trivandrum and Nagercoil Blocks in the granulite terrane of southernmost India yielded well-defined protolith emplacement ages between 1765 and ca. 2100Ma and also document variable recrystallization and/or lead-loss during the late Neoproterozoic Pan-African event at around 540Ma. Hf-in-zircon and whole rock Nd isotopic data suggest that the granitoid host rocks were derived from mixed crustal sources, and Hf-Nd model ages vary between 2.2 and 2.8Ga. A gabbroic dyke, emplaced into a charnockite protolith and deformed together with it, only contained metamorphic zircon whose mean age of 542.3±4.0Ma reflects the peak of granulite-facies metamorphism during the Pan-African high-grade event. The Sm-Nd whole-rock isotopic system of several granitoid samples dated in this study was significantly disturbed during granulite-facies metamorphism, most likely due to a CO2-rich fluid phase. Whole-rock Nd model ages are consistently older than zircon-derived Hf model ages.The Trivandrum and Nagercoil Blocks are reinterpreted as a single tectono-metamorphic terrane predominantly consisting of Palaeoproterozoic granitoids interlayered with supracrustal rocks that must be older than ca. 2100. Ma. Ductile deformation, migmatization and anatexis have obliterated the original rock relationships. These blocks probably have their counterpart in the Highland Complex of neighbouring Sri Lanka and in the high-grade Palaeoproterozoic terrane of southern Madagascar. We speculate that the southern Indian khondalites may have their counterparts in the khondalite belt of the North China Craton.

Original languageEnglish
Pages (from-to)1-37
Number of pages37
JournalGondwana Research
Volume27
Issue number1
Early online date1 Aug 2014
DOIs
Publication statusPublished - Jan 2015
Externally publishedYes

Fingerprint

ancestry
Gondwana
zircon
granitoid
terrane
granulite facies
protolith
rock
metamorphism
SHRIMP dating
khondalite
charnockite
migmatization
supracrustal rock
anatexis
ductile deformation
granulite
host rock
craton
dike

Keywords

  • Charnockite
  • Leptynite
  • Nd-Hf isotopes
  • Palaeoproterozoic
  • Zircon geochronology

Cite this

KRÖNER, A. ; SANTOSH, M. ; HEGNER, E. ; SHAJI, E. ; GENG, H. ; WONG, J. ; XIE, H. ; WAN, Y. ; SHANG, C. K. ; LIU, D. ; SUN, M. ; NANDA-KUMAR, V. / Palaeoproterozoic ancestry of Pan-African high-grade granitoids in southernmost India : Implications for Gondwana reconstructions. In: Gondwana Research. 2015 ; Vol. 27, No. 1. pp. 1-37.
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abstract = "SHRIMP dating of magmatic zircons from granitoid gneisses and charnockites of the Trivandrum and Nagercoil Blocks in the granulite terrane of southernmost India yielded well-defined protolith emplacement ages between 1765 and ca. 2100Ma and also document variable recrystallization and/or lead-loss during the late Neoproterozoic Pan-African event at around 540Ma. Hf-in-zircon and whole rock Nd isotopic data suggest that the granitoid host rocks were derived from mixed crustal sources, and Hf-Nd model ages vary between 2.2 and 2.8Ga. A gabbroic dyke, emplaced into a charnockite protolith and deformed together with it, only contained metamorphic zircon whose mean age of 542.3±4.0Ma reflects the peak of granulite-facies metamorphism during the Pan-African high-grade event. The Sm-Nd whole-rock isotopic system of several granitoid samples dated in this study was significantly disturbed during granulite-facies metamorphism, most likely due to a CO2-rich fluid phase. Whole-rock Nd model ages are consistently older than zircon-derived Hf model ages.The Trivandrum and Nagercoil Blocks are reinterpreted as a single tectono-metamorphic terrane predominantly consisting of Palaeoproterozoic granitoids interlayered with supracrustal rocks that must be older than ca. 2100. Ma. Ductile deformation, migmatization and anatexis have obliterated the original rock relationships. These blocks probably have their counterpart in the Highland Complex of neighbouring Sri Lanka and in the high-grade Palaeoproterozoic terrane of southern Madagascar. We speculate that the southern Indian khondalites may have their counterparts in the khondalite belt of the North China Craton.",
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author = "A. KR{\"O}NER and M. SANTOSH and E. HEGNER and E. SHAJI and H. GENG and J. WONG and H. XIE and Y. WAN and SHANG, {C. K.} and D. LIU and M. SUN and V. NANDA-KUMAR",
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KRÖNER, A, SANTOSH, M, HEGNER, E, SHAJI, E, GENG, H, WONG, J, XIE, H, WAN, Y, SHANG, CK, LIU, D, SUN, M & NANDA-KUMAR, V 2015, 'Palaeoproterozoic ancestry of Pan-African high-grade granitoids in southernmost India : Implications for Gondwana reconstructions', Gondwana Research, vol. 27, no. 1, pp. 1-37. https://doi.org/10.1016/j.gr.2014.07.001

Palaeoproterozoic ancestry of Pan-African high-grade granitoids in southernmost India : Implications for Gondwana reconstructions. / KRÖNER, A.; SANTOSH, M.; HEGNER, E.; SHAJI, E.; GENG, H.; WONG, J.; XIE, H.; WAN, Y.; SHANG, C. K.; LIU, D.; SUN, M.; NANDA-KUMAR, V.

In: Gondwana Research, Vol. 27, No. 1, 01.2015, p. 1-37.

Research output: Journal PublicationsReview article

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T1 - Palaeoproterozoic ancestry of Pan-African high-grade granitoids in southernmost India : Implications for Gondwana reconstructions

AU - KRÖNER, A.

AU - SANTOSH, M.

AU - HEGNER, E.

AU - SHAJI, E.

AU - GENG, H.

AU - WONG, J.

AU - XIE, H.

AU - WAN, Y.

AU - SHANG, C. K.

AU - LIU, D.

AU - SUN, M.

AU - NANDA-KUMAR, V.

PY - 2015/1

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N2 - SHRIMP dating of magmatic zircons from granitoid gneisses and charnockites of the Trivandrum and Nagercoil Blocks in the granulite terrane of southernmost India yielded well-defined protolith emplacement ages between 1765 and ca. 2100Ma and also document variable recrystallization and/or lead-loss during the late Neoproterozoic Pan-African event at around 540Ma. Hf-in-zircon and whole rock Nd isotopic data suggest that the granitoid host rocks were derived from mixed crustal sources, and Hf-Nd model ages vary between 2.2 and 2.8Ga. A gabbroic dyke, emplaced into a charnockite protolith and deformed together with it, only contained metamorphic zircon whose mean age of 542.3±4.0Ma reflects the peak of granulite-facies metamorphism during the Pan-African high-grade event. The Sm-Nd whole-rock isotopic system of several granitoid samples dated in this study was significantly disturbed during granulite-facies metamorphism, most likely due to a CO2-rich fluid phase. Whole-rock Nd model ages are consistently older than zircon-derived Hf model ages.The Trivandrum and Nagercoil Blocks are reinterpreted as a single tectono-metamorphic terrane predominantly consisting of Palaeoproterozoic granitoids interlayered with supracrustal rocks that must be older than ca. 2100. Ma. Ductile deformation, migmatization and anatexis have obliterated the original rock relationships. These blocks probably have their counterpart in the Highland Complex of neighbouring Sri Lanka and in the high-grade Palaeoproterozoic terrane of southern Madagascar. We speculate that the southern Indian khondalites may have their counterparts in the khondalite belt of the North China Craton.

AB - SHRIMP dating of magmatic zircons from granitoid gneisses and charnockites of the Trivandrum and Nagercoil Blocks in the granulite terrane of southernmost India yielded well-defined protolith emplacement ages between 1765 and ca. 2100Ma and also document variable recrystallization and/or lead-loss during the late Neoproterozoic Pan-African event at around 540Ma. Hf-in-zircon and whole rock Nd isotopic data suggest that the granitoid host rocks were derived from mixed crustal sources, and Hf-Nd model ages vary between 2.2 and 2.8Ga. A gabbroic dyke, emplaced into a charnockite protolith and deformed together with it, only contained metamorphic zircon whose mean age of 542.3±4.0Ma reflects the peak of granulite-facies metamorphism during the Pan-African high-grade event. The Sm-Nd whole-rock isotopic system of several granitoid samples dated in this study was significantly disturbed during granulite-facies metamorphism, most likely due to a CO2-rich fluid phase. Whole-rock Nd model ages are consistently older than zircon-derived Hf model ages.The Trivandrum and Nagercoil Blocks are reinterpreted as a single tectono-metamorphic terrane predominantly consisting of Palaeoproterozoic granitoids interlayered with supracrustal rocks that must be older than ca. 2100. Ma. Ductile deformation, migmatization and anatexis have obliterated the original rock relationships. These blocks probably have their counterpart in the Highland Complex of neighbouring Sri Lanka and in the high-grade Palaeoproterozoic terrane of southern Madagascar. We speculate that the southern Indian khondalites may have their counterparts in the khondalite belt of the North China Craton.

KW - Charnockite

KW - Leptynite

KW - Nd-Hf isotopes

KW - Palaeoproterozoic

KW - Zircon geochronology

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U2 - 10.1016/j.gr.2014.07.001

DO - 10.1016/j.gr.2014.07.001

M3 - Review article

AN - SCOPUS:85027925069

VL - 27

SP - 1

EP - 37

JO - Gondwana Research

JF - Gondwana Research

SN - 1342-937X

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