沒有中文摘要

The Baima igneous complex (BIC) consists of a cumulate layered gabbroic unit, a thick Fe-Ti oxide ore zone and an isotropic peralkaline quartz syenite. The BIC contains 1150 Mt of Fe, 44.8 Mt of Ti and 2.85 Mt of V and is one of at least five world class orthomagmatic oxide deposits in the Emeishan large igneous province. The formation of the oxide deposit of the BIC is debated. There are two different models on the formation of Fe-Ti-V oxide ore in the Baima intrusion. One model suggests fractional crystallization of a basaltic parental magma led to the early crystallization of Fe-Ti oxide minerals whereas the second model suggests silicate immiscibility during the early stages of the evolution of a ferro-basaltic magma. The purpose of this study is to determine if a parental magma similar to high-Ti Emeishan basalt can produce all three rock-types observed in the BIC by experimental petrology at atmospheric pressure and mid-crustal pressure (i.e. 1 GPa).
The experimental results at atmospheric pressure show that the liquidus temperature and solidus temperature of the basaltic melt are estimated to be 1303 oC and 1120 oC. The crystallization sequence is determined as: titanomagnetite, plagioclase (An65) and pyroxene (Wo43-47En32-45Fs11-23). The residual glass composition, represented by the quenched glass, evolves from lower SiO2 (SiO2 = ~45 wt %) values to higher SiO2 values (SiO2 = ~60 wt %) with corresponding decrease in Ti, Fe, Mg, Ca and increase of Na and K. The experimental results at 1 GPa show that the liquidus temperature is ~1220 oC, whereas the solidus temperature is estimated to be 980 oC. The crystallization sequence of the basaltic melt at 1 GPa is determined to be: titanomagnetite, pyroxene (Wo37-46En33-38Fs18-25) and plagioclase (An36).
The most evolved glass compositions in the low and high pressure experiments are similar to the enclaves of the Baima syenitic unit but only the low pressure experiments could reproduce the mineral compositions observed in the Baima gabbroic unit. Thus, the liquidus mineral is iron-titanium oxide which is consistent with the observation of basal oxide-ore formation in the gabbroic unit. The low pressure results of this study indicate that early crystallization of Fe-Ti oxides will occur assuming a geologically reasonable starting material and that the residual liquid is silicic. The direct implication is that the oxide deposits and spatially associated granitic rocks formed together by crystallization from a basaltic parental magma. Furthermore, it is suggested that crystallization of a typical high-Ti basaltic parental magma can produce world-class giant magmatic oxide ore deposits and that the occurrence of some alkaline granites may be an indicator of their presence.

Ali, J.R., Thompson, G.M., Zhou, M.-F., Song, X., 2005. Emeishan large igneous province, SW China. Lithos, 79(3-4): 475-489.
Andersen, T., 2002. Correction of common lead in U-Pb analyses that do not report 204Pb. Chemical Geology, 192: 59-79.
Anderson, D.J., Lindsley, D.H., Davidson, P.M., 1993. QUILF: A pascal program to assess equilibria among Fe-Mg-Mn-Ti oxides, pyroxenes,olivine, and quartz. Computers & Geosciences, 19(9): 1333-1350.
Biggar, G.M., 1972. Diopside, lithium metasilicate, and the 1968 temperature scale. Mineralogical Magazine, 38: 768-770.
Blatt, H., Tracy, R.J., Owens, B.E., 2006. Petrology: Igneous, Sedimentary, and Metamorphic (3rd Edition). W. H. Freeman and company, New York.
Bruguier, O., Lancelot, J.R., Malavieille, J., 1997. U-Pb dating on single detrital zircon grains from the Triassic Songpan-Ganze flysch (Central China) : provenance and tectonic correlations. Earth and Planetary Science Letters, 152: 217-231.
Chen, F.-W., 1990. Petrologic study on Baima ore-bearing layered mafic-ultramafic intrusion. Acta Petrologica Sinica, 4: 12-25.
Deer, W.A., Howie, R.A., Zussman, J., 1963. Rock-Forming Minerals, Framework Silicates : Feldspars. Longmans, London.
Eales, H.V., Cawthorn, R.G., 1996. The Bushveld Complex. In: Cawthorn, R.G. (Ed.), Layered Intrusions. Elsevier, Amsterdam, pp. 181-229.
Frost, B.R., Lindsley, D.H., Anderson, D.J., 1988. Fe-Ti oxide-silicate equilibria : assemblages with fayalitic olivine American Mineralogist, 73(7-8): 727-740.
Iizuka, Y., Bellwood, P., Hung, H.C., Dizon, E.Z., 2005. A non-destructive mineralogical study of nephritic artifacts from Itbayat Island, Batanes, northern Philippines. Journal of Austronesian Studies, 1(1): 83-108.
Li, X.H., 1999. U-Pb zircon ages of granites from the southern margin of the Yangtze Block: timing of Neoproterozoic Jinning: Orogeny in SE China and implications for Rodinia Assembly. Precambrian Research, 97: 43-57.
Liu, P.P., Zhou, M.F., Chen, W.T., Boone, M., Cnudde, V., 2014. Using multiphase solid inclusions to constrain the origin of the Baima Fe-Ti-(V) oxide deposit, SW China. Journal of Petrology, 55(5): 951-976.
Liu, T.C., Chen, B.S., Pan, J.J.C., P. K., Wu, S.Z., 1997. A Preliminary Report on the Experimental Study of the Two-pyroxene Andesite from Kuanyinshan, Northern Taiwan. Journal of Taiwan Normal University: Mathematics, Science & Technology, 42: 53-59.
Morimoto, N., 1988. Nomenclature of pyroxenes. Mineralogy and Petrology, 39: 55-76.
Pang, K.N., Zhou, M.F., Lindsley, D., Zhao, D., Malpas, J., 2008. Origin of Fe-Ti Oxide Ores in Mafic Intrusions: Evidence from the Panzhihua Intrusion, SW China. Journal of Petrology, 49(2): 295-313.
Roedder, E., 1979. Silicate liquid immiscibility in magmas. In: Yoder, J., H. S. (Ed.), The evolution of the igneous rocks fiftieth anniversary perspectives. Princeton Legacy Library. Princeton University Press, New Jersey, pp. 16-57.
She, Y.-W., Yu, S.-Y., Song, X.-Y., Chen, L.-M., Zheng, W.-Q., Luan, Y., 2014. The formation of P-rich Fe–Ti oxide ore layers in the Taihe layered intrusion, SW China: Implications for magma-plumbing system process. Ore Geology Reviews, 57: 539-559.
Shellnutt, J.G., 2014. The Emeishan large igneous province: A synthesis. Geoscience Frontiers, 5(3): 369-394.
Shellnutt, J.G., Denyszyn, S.W., Mundil, R., 2012. Precise age determination of mafic and felsic intrusive rocks from the Permian Emeishan large igneous province (SW China). Gondwana Research, 22(1): 118-126.
Shellnutt, J.G., Iizuka, Y., 2011. Mineralogy from three peralkaline granitic plutons of the Late Permian Emeishan large igneous province (SW China): evidence for contrasting magmatic conditions of A-type granitoids. European Journal of Mineralogy, 23(1): 45-61.
Shellnutt, J.G., Jahn, B.M., Dostal, J., 2010. Elemental and Sr–Nd isotope geochemistry of microgranular enclaves from peralkaline A-type granitic plutons of the Emeishan large igneous province, SW China. Lithos, 119(1-2): 34-46.
Shellnutt, J.G., Pang, K.-N., 2012. Petrogenetic implications of mineral chemical data for the Permian Baima igneous complex, SW China. Mineralogy and Petrology, 106(1-2): 75-88.
Shellnutt, J.G., Wang, K.L., Zellmer, G.F., Iizuka, Y., Jahn, B.M., Pang, K.N., Qi, L., Zhou, M.F., 2011. Three Fe-Ti oxide ore-bearing gabbro-granitoid complexes in the Panxi region of the Permian Emeishan large igneous province, SW China. American Journal of Science, 311(9): 773-812.
Shellnutt, J.G., Zhou, M.-F., 2007. Permian peralkaline, peraluminous and metaluminous A-type granites in the Panxi district, SW China: Their relationship to the Emeishan mantle plume. Chemical Geology, 243(3-4): 286-316.
Shellnutt, J.G., Zhou, M.-F., Yan, D.-P., Wang, Y., 2008. Longevity of the Permian Emeishan mantle plume (SW China): 1 Ma, 8 Ma or 18 Ma? Geological Magazine, 145(03): 373–388.
Shellnutt, J.G., Zhou, M.-F., Zellmer, G.F., 2009. The role of Fe–Ti oxide crystallization in the formation of A-type granitoids with implications for the Daly gap: An example from the Permian Baima igneous complex, SW China. Chemical Geology, 259(3-4): 204-217.
Watson, E.B., 1976. Two-liquid partition coefficients: experimental data and geochemical implications. Contributions to Mineralogy and Petrology, 56: 119-134
Xu, Y., Chung, S.-L., Jahn, B.-M., Wu, G., 2001. Petrologic and geochemical constraints on the petrogenesis of Permian–Triassic Emeishan flood basalts in southwestern China. Lithos, 58: 145-168.
Yang, R.-Y., Xu, W.-L., Liu, R.-X., 1997. REE geochemistry of Baima complex in the Panxi rift belt. Acta Mineralogica Sinica, 17(1): 71-77.
Zhong, H., Campbell, I.H., Zhu, W.-G., Allen, C.M., Hu, R.-Z., Xie, L.-W., He, D.-F., 2011. Timing and source constraints on the relationship between mafic and felsic intrusions in the Emeishan large igneous province. Geochimica et Cosmochimica Acta, 75(5): 1374-1395.
Zhong, H., Hu, R.Z., Wilson, A.H., Zhu, W.G., 2005. Review of the Link between the Hongge Layered Intrusion and Emeishan Flood Basalts, Southwest China. International Geology Review, 47: 971-985.
Zhong, H., Zhou, X.H., Zhou, M.F., Sun, M., Liu, B.G., 2002. Platinum-group element geochemistry of the Hongge Fe-V-Ti deposit in the Pan-Xi area, southwestern China. Mineralium Deposita, 37: 226-239.
Zhong, J.G., Zhong, H., Li, C., Zhu, W.G., He, D.F., Qi, L., 2014. Contrasting parental magma compositions for the Hongge and Panzhihua magmatic Fe-Ti-V oxide deposits, Emeishan large igneous province, SW China. Economic Geology, 109: 1763-1785.
Zhou, M.F., Malpas, J., Song, X.Y., Robinson, P.T., Sun, M., Kennedy, A.K., Lesher, C.M., Keays, R.R., 2002a. A temporal link between the Emeishan large igneous province (SW China) and the end-Guadalupian mass extinction. Earth and Planetary Science Letters, 196(3-4): 113-122.
Zhou, M.F., Robinson, P.T., Lesher, C.M., Keays, R.R., Zhang, J.C., Malpas, J., 2005. Geochemistry, petrogenesis and metallogenesis of the Panzhihua Gabbroic Layered Intrusion and associated Fe-Ti-V oxide deposits, Sichuan Province, SW China. Journal of Petrology, 46(11): 2253-2280.
Zhou, M.F., Yan, D.-P., Kennedy, A.K., Li, Y., Ding, J., 2002b. SHRIMP U-Pb zircon geochronological and geochemical evidence for Neoproterozoic arc-magmatism along the western margin of the Yangtze Block, South China. Earth and Planetary Science Letters, 196: 51-67.
Zhou, M.-F., Arndt, N.T., Malpas, J., Wang, C.Y., Kennedy, A.K., 2008. Two magma series and associated ore deposit types in the Permian Emeishan large igneous province, SW China. Lithos, 103(3-4): 352-368.
Zhou, M.-F., Zhao, J.-H., Qi, L., Su, W., Hu, R., 2006. Zircon U-Pb geochronology and elemental and Sr–Nd isotope geochemistry of Permian mafic rocks in the Funing area, SW China. Contributions to Mineralogy and Petrology, 151(1): 1-19.