Goldschmidt 2012 Conference Abstracts
Metallogenic age and tectonic
settings of Hongtoushan Cu-Zn
deposit in Liaoning province, China
：Evidences from zircon
Y. QIAN1,2*, F.Y. SUN1 , AND B.L. LI1
1College
of Earth Sciences, Jilin University, Changchun,
China ,qianye@jlu.edu.cn(* presenting author)
2State Key Laboratory of Continental Dynamics, Northwest
University, Xi'an, China
Hongtoushan Cu-Zn deposit is located in northern Lioaning
province in North China Craton, which is the only one Archean
VMS deposit in China. The immediate ore-hosting rocks in the
deposit are biotite plagioclase gneiss and amphibolite which were
subjected to amphibolite facies metamorphism. The geological and
geochemical data[1] reveal that original rocks of the ore-hosting
rocks are calc-alkaline tholeiite-andesite-dacite series and formed in
island-arc tectonic settings.
In order to determine the metallogenic age and tectonic
background of the deposit, we have maded the cathodoluminescence
(CL) images and LA-ICP-MS U-Pb dating of the zircons from the
ore-hosting
rocks. In CL images, there occur relatively fine
oscillatory zoning within the zircon center,while it gradually vanishes
toward its edge. It is suggested that the zircons are of magmatic
origin and suffered metamorphic superimposition [2]. Zircons from
the biotite plagioclase gneiss have U-Pb ages of 2521-2580Ma, with
the upper intercept age of 2552Ma (MSWD=0.84, n=24).
Correspondingly, zircons from the amphibolite have the upper
intercept age of 2550Ma(MSWD=0.78, n=16).
Based on geological data and zircon U-Pb dating, it has been
concluded that the forming age of Hongtoushan Cu-Zn deposit is
2550Ma. During that time, drifting of ancient continents caused the
subduction of the oceanic crust, which resulted in the submarine
volcanism. In the intermittent period of volcanism, the hot orebearing fluids as black smoker were mixed with cold seawater and
formed the Hongtoushan VMS deposit. During the subsequent arccontinent collision, the deposit was subjected to the metamorphism
and deformation.
[1] Zai,Yang(1984) Geological Rev. 30, 523-525. [2] Hoskin, Black
(2000) J. metamorphic Geol. 18, 423-439.
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