Details
| Original language | English |
|---|---|
| Pages (from-to) | 118-138 |
| Number of pages | 21 |
| Journal | Lithos |
| Volume | 172-173 |
| Early online date | 20 Apr 2013 |
| Publication status | Published - Jul 2013 |
Abstract
The Liujiawa pluton which is located near the eastern boundary of the Dabie orogen is composed of multiple lithologic units including mainly gabbronorites, diorites, granodiorites and hornblende gabbros. Gabbronorites and hornblende gabbros occur as enclaves in dioritic hosts which show gradual contact with granodiorites. Zircon U-Pb dating indicates that gabbronorites and diorites formed coevally at ~128Ma, but they have distinct zircon Hf isotopes with εHf(t) of -26 to -23 (gabbronorite) and of -32 to -27 (diorite) respectively. Petrographic observations and rock-forming mineral compositions clearly show mixing between mafic and felsic magma end-members, which might have formed the homogeneous whole-rock Sr-Nd isotopes with εNd(t) of -17 to -25 and initial 87Sr/86Sr of 0.707 to 0.709. As revealed by zircon Hf isotopes, F concentrations in amphibole and biotite and thermodynamic modeling of crystallization, the gabbronorites represent enriched lithospheric mantle-derived magmas which evolved by fractional crystallization of orthopyroxene, clinopyroxene, magnetite and/or amphibole, whereas the granodiorites may be derived from the Dabie Archean basement. Mineralogical and geochemical data as well as major and trace element modeling show that the origin of diorites, previously interpreted as high-Mg adakites, can be explained by magma mixing between the crust-derived granodioritic magmas and the differentiation products of mantle-derived gabbronoritic magmas. As a result, the high-Mg adakite-like geochemistry of the diorites is a consequence of magma differentiation at a crustal depth, involving fractional crystallization and magma mixing, rather than an intrinsic feature of primitive melts. The mantle upwelling in the adjacent central Middle-Lower Yangtze River metallogenic (MLYR) belt during Late Jurassic-Early Cretaceous belt might have acted as a precursor and triggered the partial melting of lithospheric mantle beneath the eastern Dabie orogen and the further melting of orogenic basement, consistent with the model of Zhang et al. (2010) suggesting a magmatic link between the MLYR belt and the southeastern Dabie orogen.
Keywords
- Dabie orogen, Fractional crystallization, High-Mg adakite, Magma mixing, MLYR belt, Tan-Lu fault
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geology
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Lithos, Vol. 172-173, 07.2013, p. 118-138.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Mineralogical and geochemical constraints on contribution of magma mixing and fractional crystallization to high-Mg adakite-like diorites in eastern Dabie orogen, East China
AU - Zhang, Chao
AU - Ma, Changqian
AU - Holtz, Francois
AU - Koepke, Jürgen
AU - Wolff, Paul Eric
AU - Berndt, Jasper
N1 - Funding Information: We thank Yong-Sheng Liu and Jin-Hui Yang for their help during zircon U–Pb dating and zircon Hf isotope analysis, respectively. We thank the comments from Haijin Xu and an anonymous reviewer which improved the paper greatly. Editor-in-chief Nelson Eby is appreciated for efficient editorial handling. This work has been supported by National Nature Science Foundation of China (NSFC) (grants 41272079 , 90814004 and 40334037 ) and China Geological Survey (grant 1212011121270 ). C. Zhang appreciates scholarships provided by China Scholarship Council (CSC) and German Academic Exchange Service (DAAD) . Copyright: Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013/7
Y1 - 2013/7
N2 - The Liujiawa pluton which is located near the eastern boundary of the Dabie orogen is composed of multiple lithologic units including mainly gabbronorites, diorites, granodiorites and hornblende gabbros. Gabbronorites and hornblende gabbros occur as enclaves in dioritic hosts which show gradual contact with granodiorites. Zircon U-Pb dating indicates that gabbronorites and diorites formed coevally at ~128Ma, but they have distinct zircon Hf isotopes with εHf(t) of -26 to -23 (gabbronorite) and of -32 to -27 (diorite) respectively. Petrographic observations and rock-forming mineral compositions clearly show mixing between mafic and felsic magma end-members, which might have formed the homogeneous whole-rock Sr-Nd isotopes with εNd(t) of -17 to -25 and initial 87Sr/86Sr of 0.707 to 0.709. As revealed by zircon Hf isotopes, F concentrations in amphibole and biotite and thermodynamic modeling of crystallization, the gabbronorites represent enriched lithospheric mantle-derived magmas which evolved by fractional crystallization of orthopyroxene, clinopyroxene, magnetite and/or amphibole, whereas the granodiorites may be derived from the Dabie Archean basement. Mineralogical and geochemical data as well as major and trace element modeling show that the origin of diorites, previously interpreted as high-Mg adakites, can be explained by magma mixing between the crust-derived granodioritic magmas and the differentiation products of mantle-derived gabbronoritic magmas. As a result, the high-Mg adakite-like geochemistry of the diorites is a consequence of magma differentiation at a crustal depth, involving fractional crystallization and magma mixing, rather than an intrinsic feature of primitive melts. The mantle upwelling in the adjacent central Middle-Lower Yangtze River metallogenic (MLYR) belt during Late Jurassic-Early Cretaceous belt might have acted as a precursor and triggered the partial melting of lithospheric mantle beneath the eastern Dabie orogen and the further melting of orogenic basement, consistent with the model of Zhang et al. (2010) suggesting a magmatic link between the MLYR belt and the southeastern Dabie orogen.
AB - The Liujiawa pluton which is located near the eastern boundary of the Dabie orogen is composed of multiple lithologic units including mainly gabbronorites, diorites, granodiorites and hornblende gabbros. Gabbronorites and hornblende gabbros occur as enclaves in dioritic hosts which show gradual contact with granodiorites. Zircon U-Pb dating indicates that gabbronorites and diorites formed coevally at ~128Ma, but they have distinct zircon Hf isotopes with εHf(t) of -26 to -23 (gabbronorite) and of -32 to -27 (diorite) respectively. Petrographic observations and rock-forming mineral compositions clearly show mixing between mafic and felsic magma end-members, which might have formed the homogeneous whole-rock Sr-Nd isotopes with εNd(t) of -17 to -25 and initial 87Sr/86Sr of 0.707 to 0.709. As revealed by zircon Hf isotopes, F concentrations in amphibole and biotite and thermodynamic modeling of crystallization, the gabbronorites represent enriched lithospheric mantle-derived magmas which evolved by fractional crystallization of orthopyroxene, clinopyroxene, magnetite and/or amphibole, whereas the granodiorites may be derived from the Dabie Archean basement. Mineralogical and geochemical data as well as major and trace element modeling show that the origin of diorites, previously interpreted as high-Mg adakites, can be explained by magma mixing between the crust-derived granodioritic magmas and the differentiation products of mantle-derived gabbronoritic magmas. As a result, the high-Mg adakite-like geochemistry of the diorites is a consequence of magma differentiation at a crustal depth, involving fractional crystallization and magma mixing, rather than an intrinsic feature of primitive melts. The mantle upwelling in the adjacent central Middle-Lower Yangtze River metallogenic (MLYR) belt during Late Jurassic-Early Cretaceous belt might have acted as a precursor and triggered the partial melting of lithospheric mantle beneath the eastern Dabie orogen and the further melting of orogenic basement, consistent with the model of Zhang et al. (2010) suggesting a magmatic link between the MLYR belt and the southeastern Dabie orogen.
KW - Dabie orogen
KW - Fractional crystallization
KW - High-Mg adakite
KW - Magma mixing
KW - MLYR belt
KW - Tan-Lu fault
UR - http://www.scopus.com/inward/record.url?scp=84877826694&partnerID=8YFLogxK
U2 - 10.1016/j.lithos.2013.04.011
DO - 10.1016/j.lithos.2013.04.011
M3 - Article
AN - SCOPUS:84877826694
VL - 172-173
SP - 118
EP - 138
JO - Lithos
JF - Lithos
SN - 0024-4937
ER -