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Petrogenesis and Mineralization of Two‐Stage A‐Type Granites in Jiuyishan, South China: Constraints from Whole‐rock Geochemistry, Mineral Composition and Zircon U‐Pb‐Hf Isotopes
Author(s) -
LIU Ye,
LAI Jianqing,
XIAO Wenzhou,
JEFFREY Dick,
DU Rijun,
LI Shuanglian,
LIU Chaoyun,
WEN Chunhua,
YU Xiaohang
Publication year - 2019
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.13864
Subject(s) - pluton , zircon , geochemistry , geology , feldspar , mineralization (soil science) , partial melting , petrogenesis , quartz , mantle (geology) , tectonics , paleontology , soil water , soil science
The Jiuyishan complex massif, located in the northern section of the Nanling region, is a combination of five plutons, namely, the Xuehuading, Jinjiling, Pangxiemu, Shaziling and Xishan plutons. Whole‐rock geochemistry, mineral electron microprobe analysis, zircon U‐Pb dating and Hf isotope analysis were carried out for the Jinjiling and Pangxiemu plutons. The zircon U‐Pb dating yields weighted mean ages of 152.9±0.9 Ma for the Jinjiling pluton and 151.7±1.5 Ma for the Pangxiemu pluton, with a narrow gap between them. The Jinjiling and Pangxiemu plutons both have geochemical characteristics of high SiO 2 , Al 2 O 3 , Na 2 O, K 2 O and low TiO 2 , MgO, CaO, P 2 O 5 contents, with intense depletionS in Sr, Ba, Ti, Eu and enrichments in Ga, FeO T and HFSE, and these characteristics reflect an A‐type affinity. From the Jinjiling to the Pangxiemu plutons, the mineral composition of mica changes from lepidomelane to zinnwaldite, with increases in F, Li 2 O and Rb 2 O contents. The mineral composition of zircon changes from low Zr/Hf to high Zr/Hf, with increasing HfO 2 , P 2 O 5 and UO 2 +ThO 2 +Y 2 O 3 contents. The mineral compositions of feldspar indicate that the Pangxiemu pluton contains more alkali feldspar than the Jinjiling pluton. The whole‐rock geochemistry and mineral compositions reveal a higher degree of differentiation for the Pangxiemu pluton. The nearly uniform ε Hf ( t ) indicates the same source region for the two plutons: both were derived from partial melting of the lower crust, with small contributions of mantle materials. In addition, higher F, lower Nb/Ta and Zr/Hf ratios in the Pangxiemu Pluton suggest a closer relationship with the rare metal mineralization than for the Jinjiling pluton.