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Two Origins of Illite at the Dexing Porphyry Cu Deposit, East China: Implications for Ore-Forming Fluid Constraint on Illite Crystallinity

Published online by Cambridge University Press:  01 January 2024

Zhangdong Jin ,
Jinchu Zhu ,
Junfeng Ji ,
Fuchun Li  and
Xinwei Lu
Zhangdong Jin*
Affiliation:
Lake Sediment and Environment Laboratory, Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, China State Key Laboratory for Research of Mineral Deposits, Department of Earth Sciences, Nanjing University, Nanjing 210093, China
Jinchu Zhu
Affiliation:
State Key Laboratory for Research of Mineral Deposits, Department of Earth Sciences, Nanjing University, Nanjing 210093, China
Junfeng Ji
Affiliation:
State Key Laboratory for Research of Mineral Deposits, Department of Earth Sciences, Nanjing University, Nanjing 210093, China
Fuchun Li
Affiliation:
State Key Laboratory for Research of Mineral Deposits, Department of Earth Sciences, Nanjing University, Nanjing 210093, China
Xinwei Lu
Affiliation:
State Key Laboratory for Research of Mineral Deposits, Department of Earth Sciences, Nanjing University, Nanjing 210093, China Institute of Geography, Chinese Academy of Sciences, Beijing 100101, China
*
*E-mail address of corresponding author: zhdjin@niglas.ac.cn
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Abstract

Illite is a distinctive clay mineral formed by K alteration within hydrothermal alteration zones in porphyry Cu deposits. Based on differences in spatial distribution, Kübler index, number of swelling layers, and polytype, two kinds of illite are recognized within the Dexing porphyry Cu deposit, East China. One is a hydrothermal mineral within hydrothermally-altered granodiorite porphyry and altered tuffaceous phyllite near the contact zone with the granodiorite porphyry cupola. The hydrothermal illite is formed by illitization of plagioclase and/or micas during hydrothermal fluid-rock interaction. The considerable variation of their higher Kübler indices (0.17–1.41°Δ2θ) with swelling layer is affected by fluid/rock ratio or fluid flux. The other type of illite is a product of low-grade metamorphism within tuffaceous phyllite away from the porphyry cupola (>2 km), and has a lower Kübler index (0.06–0.13°Δ2θ), a 2M1 polytype, and no swelling layers. We suggest that, within the mineralized alteration zone, the lower the Kübler index, the stronger the degree of alteration, and the higher the copper grade. This is caused by a higher fluid/rock ratio in the middle-upper portions of the contact zone.

Keywords

AlterationHydrothermal FluidKübler IndexLow-grade MetamorphismPorphyry Cu Deposit
Type
Research Article
Information
Clays and Clay Minerals , Volume 50 , Issue 3 , June 2002 , pp. 381 - 387
Copyright
Copyright © 2002, The Clay Minerals Society

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References

Bell, T.E., (1986) Micro structure in mixed-layer illite/smectite and its relationship to the reaction of smectite to illite Clays and Clay Minerals 34 146–154 10.1346/CCMN.1986.0340205.CrossRefGoogle Scholar
Biscaye, P.E., (1965) Mineralogy and sedimentation of recent deep-sea clay in the Atlantic Ocean and adjacent seas and oceans Geological Society of America Bulletin 76 803–831 10.1130/0016-7606(1965)76[803:MASORD]2.0.CO;2.CrossRefGoogle Scholar
Buatier, M.D. Peacor, D.R. and O’Neil, J.R., (1992) Smectite-illite transition in Barbados Accretionary wedge sediments: TEM and AEM evidence for dissolution/crystallization at low temperature Clays and Clay Minerals 40 65–80 10.1346/CCMN.1992.0400108.CrossRefGoogle Scholar
Drits, V.A. Eberl, D.D. and Środoń, J., (1998) XRD measurement of mean thickness, thickness distribution and strain for illite and illite-smectite crystallites by the Bertaut-Warren-Averbach technique Clays and Clay Minerals 46 38–50 10.1346/CCMN.1998.0460105.CrossRefGoogle Scholar
Duba, D. and Williams-Jones, A.E., (1983) The application of illite crystallinity, organic matter reflectance, and isotopic techniques to mineral exploration: A case study in southwestern Gaspé, Quebec Economic Geology 78 1350–1363 10.2113/gsecongeo.78.7.1350.CrossRefGoogle Scholar
Eberl, D.D. and Hower, J., (1976) Kinetics of illite formation Geological Society of America Bulletin 9 1326–1330 10.1130/0016-7606(1976)87<1326:KOIF>2.0.CO;2.2.0.CO;2>CrossRefGoogle Scholar
Eberl, D.D. and Velde, B., (1989) Beyond the Kübler Index Clay Minerals 24 571–577 10.1180/claymin.1989.024.4.01.CrossRefGoogle Scholar
Elliott, W.C. and Matisoff, G., (1996) Evaluation of kinetic models for smectite to illite transformation Clays and Clay Minerals 44 77–87 10.1346/CCMN.1996.0440107.CrossRefGoogle Scholar
Grathoff, G.H. and Moore, D.M., (1996) Illite polytype quantification using WILDFIRE© calculated X-ray diffraction patterns Clays and Clay Minerals 44 835–841 10.1346/CCMN.1996.0440615.CrossRefGoogle Scholar
Harvey, C.C. and Browne, P.R.L., (1991) Mixed-layer clay geothermometry in the Wairakei geothermal field, New Zealand Clays and Clay Minerals 39 614–621 10.1346/CCMN.1991.0390607.CrossRefGoogle Scholar
Hillier, S. Matyas, J. Matter, A. and Vasseur, G., (1995) Illite/smectite diagenesis and its variable correlation with vitrinite reflectance in the Pannonian basin Clays and Clay Minerals 43 174–183 10.1346/CCMN.1995.0430204.CrossRefGoogle Scholar
Huang, W.L. Longo, J.M. and Pevear, D.R., (1993) An experimentally derived kinetic model for smectite-to-illite conversion and its use as a geothermometer Clays and Clay Minerals 41 162–177 10.1346/CCMN.1993.0410205.CrossRefGoogle Scholar
Inoue, A. and Kitagawa, R., (1994) Morphological characteristics of illitic clay minerals from a hydrothermal system American Mineralogist 79 700 711.Google Scholar
Ji, J. Browne, P.R.L. and Liu, Y., (1997) Kinetic model for the smectite to illite transformation in an active geothermal system Chinese Science Bulletin 42 2313 2315.Google Scholar
Ji, J. Chen, J. and Lu, H., (1999) Origin of illite in the loess from the Luochuan area, Loess Plateau, Central China Clay Minerals 34 525–532 10.1180/000985599546398.CrossRefGoogle Scholar
Jin, Z. Zhu, J. Ni, P. and Li, F., (2000) Further discussions on the source of ore-forming materials in the Dexing Porphyry Copper Deposit, Jiangxi Province Geological Review 46 255–262 in Chinese.Google Scholar
Kisch, H.J., (1991) Illite crystallinity: recommendation on sample preparation, X-ray diffraction settings and inter-laboratory samples Journal of Metamorphic Geology 9 665–670 10.1111/j.1525-1314.1991.tb00556.x.CrossRefGoogle Scholar
Lanson, B. Velde, B. and Meunier, A., (1998) Late-stage diagenesis of illitic clay minerals as seen by decomposition of X-ray diffraction patterns: contrasted behaviors of sedimentary basins with different burial histories Clays and Clay Minerals 46 69–78 10.1346/CCMN.1998.0460108.CrossRefGoogle Scholar
Maxwell, D.T. and Hower, J., (1967) High-grade diagenesis and low-grade metamorphism of illite in the Precambrian Belt series American Mineralogist 52 843 857.Google Scholar
Meng, L.Y., (1992) Alteration and mineralization in the porphyry copper and molybdenum deposits Chinese Science Bulletin 37 2162 2164.Google Scholar
Pollastro, R.M., (1993) Considerations and applications of the illite/smectite geothermometer in hydrocarbon bearing rocks of Miocene to Mississippian age Clays and Clay Minerals 41 119–133 10.1346/CCMN.1993.0410202.CrossRefGoogle Scholar
Rask, J.H. Bryndzia, L.T. Braunsdorf, N.R. and Murray, T.E., (1997) Smectite illitization in Pliocene-age gulf of Mexico mudrocks Clays and Clay Minerals 45 99–109 10.1346/CCMN.1997.0450112.CrossRefGoogle Scholar
Reynolds, R.C. Jr, (1963) Potassium-rubidium ratios and polymorphism in illites and microclines from the clay size fractions of Proterozoic carbonate rocks Geochimica et Cosmochimica Acta 27 1097–1112 10.1016/0016-7037(63)90092-9.CrossRefGoogle Scholar
Reynolds, R.C. Jr. (1985) NEWMOD © a computer program for the calculation of one-dimensional diffraction patterns of mixed-layered clays. Reynolds, R.C. Jr., 8 Brook Rd., Hanover, New Hampshire, USA.Google Scholar
Schiffman, P. and Staudigel, H., (1995) The smectite to chlorite transition in a fossil seamount hydrothermal system: the Basement Complex of La Palma, Canary Islands Journal of Metamorphic Geology 13 487–498 10.1111/j.1525-1314.1995.tb00236.x.CrossRefGoogle Scholar
Środoń, J. Eberl, D.D. and Bailey, S.W., (1984) Illite Micas Washington, D.C. Mineralogical Society of America 495–544 10.1515/9781501508820-016 Reviews in Mineralogy, 13 .CrossRefGoogle Scholar
Środoń, J. Morgan, D.J. Eslinger, E.V. Eberl, D.D. and Karlinger, M.R., (1986) Chemistry of illite/smectite and end-member illite Clays and Clay Minerals 34 368–378 10.1346/CCMN.1986.0340403.CrossRefGoogle Scholar
Velde, B. and Vasseur, G., (1992) Estimation of the diagenetic smectite to illite transformation in time-temperature space American Mineralogist 77 967 976.Google Scholar
Warr, L.N. and Rice, A.H.N., (1994) Interlabortory standardization and calibration of clay mineral crystallinity and crystallite size data Journal of Metamorphic Geology 12 141–152 10.1111/j.1525-1314.1994.tb00010.x.CrossRefGoogle Scholar
Weaver, C.E. and Broekstra, B.R., (1984) Illite-mica Shale, Slate Metamorphism in Southern Appalachians Amsterdam Elsevier 67–199 10.1016/B978-0-444-42264-4.50009-8.CrossRefGoogle Scholar
Whitney, G., (1990) Role of water in the smectite-to-illite reaction Clays and Clay Minerals 38 343–350 10.1346/CCMN.1990.0380402.CrossRefGoogle Scholar
Yau, Y.C. Peacor, D.R. and McDowell, S.D., (1987) Smectite-to-illite reactions in Salton Sea shales: a transmission and analytical electron micros copy study Journal of Sedimentary Petrology 57 335 342.Google Scholar
Zhu, X. Huang, C. and Rui, Z., (1983) Dexing Porphyry Cu Deposits Beijing Geology Press 1–336 (in Chinese).Google Scholar