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The Gold Mineralization Background of Napo Permian Mafic Magmatism in Western Guangxi Province: Evidence for Emeishan Mantle Plume and Paleotethyan Subduction Interaction
Author(s) -
CHEN Xuefeng,
LIU Xijun,
GUO Lin,
SHI Yu,
HUANG Wenlong,
LIAO Shuai
Publication year - 2014
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 - 10.1111/1755-6724.12375_10
Subject(s) - geochemistry , geology , mafic , magmatism , mantle plume , mineralization (soil science) , permian , mantle (geology) , mining engineering , tectonics , structural basin , seismology , geomorphology , soil water , lithosphere , soil science
area, Western Guangxi Province, Which are composed of pillow basalts and layered sub-volcanic diabases. According to the concentration of TiO2=2.8% and Ti/ Y=500, Napo mafic rocks can be divide into high-Ti group and low-Ti group. Rocks of the high-Ti group have lower SiO2 (average 49.52 wt%), MgO (average 5.75 wt%), higher FeOt (average 12.09 wt%), TiO2 (average 3.01 wt%) and P2O5 (0.12~0.25 wt%) than the low-Ti group(53.23 wt%, 6.58 wt % , 10.97 wt % , 1.17 wt % and 0.04~0.08 wt % respectively). In Nb/Y-Zr/TiO2 diagram, except for the sample NP-12-24, other high-Ti samples plot into the fields of alkaline basalt; Low-Ti group plot into the fields of sub-alkaline basalt, and the high-Ti sample NP-12-24 plot into the fields of sub-alkaline basalt between the two groups above. And in FeOt/MgO-FeOt diagram, all low-Ti samples plot into the fields of tholeiite. In chrondrite-normalized REE patterns(Fig. 1a), two groups have different patterns. The high-Ti group shows LREE enrichment, patterns in a narrow distribution range. They have (La/Yb)cn ratios between 5.0~6.3 and positive Eu anomalies. The patterns distribute in the fields of the Emeishan high-Ti basalts, and sub-parallel to them. Whereas low-Ti group has (La/Yb)cn ratios between 1.2~1.7, has relatively flat chondrite-normalized REE patterns, similar to E-MORB, and exhibits positive Eu anomalies. The sample NP-12-24 has the same REE patterns as the low-Ti mafic rock, but its REE contents are more higher. As shown in the primitive mantle-normalized spidergrams(Fig. 1b), two groups also have different patterns. The high-Ti group is enriched in LILE (Rb, Ba, Th, U, etc) and HFSE(Nb, Ta, Zr, Hf, Ti). The patterns close to OIB and sub-parallel to it, distributing in the fields of the Emeishan high-Ti basalts. Unlike the high-Ti group, the low-Ti rocks are enriched in LILE (Rb, Th, U, Sr), Pb. Ba showing positive to negative anomalies. The rocks have pronounced negative Nb, Ta anomalies, the patterns sub-parallel to the island-arc basalts and distribute CHEN Xuefeng, LIU Xijun, GUO Lin, SHI Yu, HUANG Wenlong and LIAO Shuai, 2014. The Gold Mineralization Background of Napo Permian Mafic Magmatism in Western Guangxi Province: Evidence for Emeishan Mantle Plume and Paleotethyan Subduction Interaction. Acta Geologica Sinica (English Edition), 88(supp. 2): 697-699.