Plagioclase Crystal Populations of the Granodiorite in the Jiaqi-style Porphyry Cu-Mo Deposit, Eastern Kunlun Orogen, Qinghai, and their Metallogenic Implications
LUO Zhao-hua1, GUO Jing1, HEI Hui-xin1, WANG Bing-zhang2, WANG Tao2
1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;
2. Qinghai Geological Survey Institute, Xining 810012, China
Abstract：In recent years, more and more researchers accept the opinion that igneous rocks are composed of crystal populations. In this article, taking the granodiorite in the Jiaqi-style porphyry Cu-Mo deposit, Eastern Kunlun orogen, as an example, we attempt to clarify the content of the term "crystal population", and indroduce the methodology and implications for studying crystal populations. The petrography and CL images indicate that plagioclase grains in the granodiorite can be subdivided into five types. Chemical variation across the plagioclase crystal grains by EMPA further suggests that these five types of crystals have crystallized in different conditions and processes so that they are of different crystal populations. According to principles of the equilibrium thermodynamics, the five crystal populations are likely to be derived from five different magma subsystems, which suggests that the parental magmas are the product of magma mixing of a multiple chamber system. The mixing magmas must have experienced a quickly solidification process. The new insights are important for revealing origin of the porphyry deposits.
罗照华, 郭晶, 黑慧欣, 王秉璋, 王涛. 东昆仑造山带家琪式斑岩型Cu-Mo矿床中花岗闪长岩的斜长石晶体群及其成矿意义[J]. 矿物岩石地球化学通报, 2018, 37(2): 214-228.
LUO Zhao-hua, GUO Jing, HEI Hui-xin, WANG Bing-zhang, WANG Tao. Plagioclase Crystal Populations of the Granodiorite in the Jiaqi-style Porphyry Cu-Mo Deposit, Eastern Kunlun Orogen, Qinghai, and their Metallogenic Implications. Acta Metallurgica Sinica, 2018, 37(2): 214-228.
Alexander R C. 1998. On the emplacement of tabular granites. Journal of the Geological Society, 155(5): 853-862
Charlier B L A, Wilson C J N, Lowenstern J B, Blake S, Van CALSTEREN P W, Davidson J P. 2005. Magma generation at a large, hyperactive silicic volcano (Taupo, New Zealand) revealed by U-Th and U-Pb systematics in zircons. Journal of Petrology, 46(1): 3-32
Cheng L L, Yang Z F, Zeng L, Wang Y, Luo Z H. 2014. Giant plagioclase growth during storage of basaltic magma in Emeishan Large Igneous Province, SW China. Contributions to Mineralogy and Petrology, 167(2): 971, doi: 10.1007/s00410-014-0971-0
Davidson J P, Morgan D J, Charlier B L A, Harlou R, Hora J. 2007. Tracing magmatic processes and timescales through mineral-scale isotopic data. Annual Reviews of Earth and Planetary Sciences, 35(1): 273-311
Deer W A, Howie R A, Zussman J. 2001. Framework silicates: feldspars. 2nd ed. London: The Geological Society, 972
Gill J, Reagan M, Tepley F, Malavassie E. 2006. Arenal Volcano. Costa Rica: Magma Genesis and Volcanology Processes, 157: 1-8
Ingebritsen S E, Manning C E. 2010. Permeability of the continental crust: Dynamic variations inferred from seismicity and metamorphism: Geofluids, 10(1-2): 193-205
Morse S A. 1984. Cation diffusion in plagioclase feldspar. Science, 225(4661): 504-505
Rutherford M J. 2008. Magma ascent rates. Reviews in Mineralogy and Geochemistry, 69(1): 241-271
Burgisser A, Bergantz G W, Breidenthal R E. 2005. Addressing complexity in laboratory experiments: the scaling of dilute multiphase flows in magmatic systems. Journal of Volcanology and Geothermal Research, 141(3-4): 245-265
Marsh B D. 1996. Solidification fronts and magmatic evolution. Mineralogical Magazine, 60(1): 5-40
Martin R F. 2012. The petrogenesis of anorogenic felsic magmas and AMCG suites: Insights on element mobility and mutual cryptic contamination from polythermal experiments. Lithos, 151: 35-45
Rothstein D A, Manning C E. 2003. Geothermal gradients in continental magmatic arcs: Constraints from the eastern Peninsular Ranges batholith, Baja California, México. Geological Society of America, Special Paper, 374: 337-354
Waters L E, Andrews B J, Lange R A. 2015. Rapid crystallization of plagioclase phenocrysts in silicic melts during fluid-saturated ascent: Phase equilibrium and decompression experiments. Journal of Petrology, 56(5): 981-1006
Zellmer G F, Annen C. 2008. An introduction to magma dynamics. In: Annen C, Zellmer G F, eds. Dynamics of Crustal Magma Transfer, Storage and Differentiation. Geological Society, London, Special Publications, 304: 1-13
Jerram D A, Martin V M. 2008. Understanding crystal populations and their significance through the magma plumbing system. In: Annen C, Zellmer G F, eds. Dynamics of Crustal Magma Transfer, Storage and Differentiation. Geological Society, London, Special Publications, 304: 133-148
贵公网安备 52011502002747号