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Petrogenesis of volcanic and intrusive rocks of the Zhuanqiao stage, Luzong Basin, Yangtze metallogenic belt, east China: implications for ore deposition
Citation
Yuan, F and Zhou, T and Liu, J and Fan, Y and Cooke, DR and Jowitt, SM, Petrogenesis of volcanic and intrusive rocks of the Zhuanqiao stage, Luzong Basin, Yangtze metallogenic belt, east China: implications for ore deposition, International Geology Review, 53, (5-6) pp. 526-541. ISSN 0020-6814 (2011) [Refereed Article]
Copyright Statement
Copyright 2011 Taylor & Francis.
DOI: doi:10.1080/00206814.2010.496246
Abstract
The Mesozoic Luzong volcanic basin is located in the Lower Yangtze River faultdepression,
along the northern margin of the Yangtze Block. Volcanic and plutonic
rocks are widely distributed in the basin and are spatially related to Cu, Fe, Au, Pb, and
Zn ore deposits. The magmatic rocks are dominated by an alkali-rich shoshonitic suite
of volcanics and intrusives, including both a trachybasalt-basaltic trachyandesite-trachyte
series and a diorite-monzonite-syenite-alkali feldspar granite series. Volcanic
sequences within the Luzong Basin are subdivided into four stages, namely the Longmenyuan,
Zhuanqiao, Shuangmiao, and Fushan stages with magmatism occurring
between 136 and 124 Ma. Most mineral deposits were formed during the Zhuanqiao
stage from about 134 to 131 Ma, during a longer (140–130 Ma) period of transition
from compression to extension within the Luzong Basin.
Major element concentrations in the Zhuanqiao volcanic rocks range from 53.97 to
62.59 wt.% SiO2, 0.57–0.94 wt.% TiO2, 3.52–6.07 wt.% Na2O, and 3.60–8.66 wt.%
K2O. Combined K2O + Na2O totals lie between 7.87 and 12.49 wt.%, and
K2O + Na2O/Al2O3 ranges between 0.47 and 0.71. In comparison, the Zhuanqiao
intrusions have SiO2 concentrations between 52.19 and 67.70 wt.%, TiO2 between
0.26 and 1.13 wt.%, Na2O between 1.33 and 6.55 wt.%, and K2O between 2.15 and
8.25 wt.%, with K2O + Na2O values ranging from 5.92 to 12.39 wt.% and
K2O + Na2O/Al2O3 ratios between 0.37 and 0.75. The Zhuanqiao volcanic rocks have
an average ΣREE (rare earth element) content of 223.17 ppm, whereas the average
ΣREE of the Zhuanqiao intrusives is 250.06 ppm. Weak negative Eu anomalies
(Eu/Eu* between 0.69 and 1.00) characterize the volcanics, whereas a larger range
with more significant negative Eu anomalies (Eu/Eu* values of 0.35–0.94) is present in
the plutonics. The Zhuanqiao volcanic rocks and plutons have (Nb/Th)PM ratios of
0.05–0.14 and 0.02–0.14 and (La/Sm)PM of 3.33–4.95 and 3.36–7.29, respectively. Initial
87Sr/86Sr and 143Nd/144Nd ratios and ∈Sr(t) and ∈Nd(t) of the Zhuanqiao volcanic
rocks are 0.7059–0.7067, 0.51194–0.51218, 22.0–33.3, and −10.2 to −5.5, respectively;
those of the intrusives are 0.7060–0.7082 and 0.51203–0.51214 and 23.3–54.7
and −8.6 to −6.4, respectively. The geochemistry presented here suggests that both volcanic
and intrusive Zhuanqiao stage magmatic rocks were cogenetic and were probably
derived from an enriched mantle (EM) source, most probably metasomatized mantle relating
to the EM type-I (EM-I). The Zhuanqiao stage magmatism apparently was controlled
by differentiation and assimilation of crustal material in a high-level magma chamber. Formation of the Zhuanqiao stage magmatic rocks coincided with the formation of much of the Cu and Fe mineralization within the Luzong Basin. This coeval magmatism and mineralization during the Zhuanqiao stage can be subdivided into three differing mineral deposit affinities: magmatism associated with magmato-hydrothermal vein Cu (e.g. the Jingbian, Shimenan, and Chuanshandong deposits), porphyry-hosted Fe (e.g. the Luohe and Nihe deposits), and skarn Fe (e.g. the Longqiao deposit). Combining geological characteristics with variations in SiO2, K2O + Na2O, and MgO enabled the division of the Zhuanqiao stage magmatism in the Luzong Basin into geochemically distinct units associated with these differing styles of mineralization.
Item Details
Item Type: | Refereed Article |
---|---|
Keywords: | petrogenesis Yangtze metallogenic belt E China |
Research Division: | Earth Sciences |
Research Group: | Geology |
Research Field: | Igneous and metamorphic petrology |
Objective Division: | Mineral Resources (Excl. Energy Resources) |
Objective Group: | Mineral exploration |
Objective Field: | Copper ore exploration |
UTAS Author: | Cooke, DR (Professor David Cooke) |
ID Code: | 74874 |
Year Published: | 2011 |
Web of Science® Times Cited: | 28 |
Deposited By: | Centre for Ore Deposit Research - CODES CoE |
Deposited On: | 2011-12-14 |
Last Modified: | 2017-11-02 |
Downloads: | 0 |
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