Hostname: page-component-cd9895bd7-fscjk Total loading time: 0 Render date: 2024-12-27T06:08:19.121Z Has data issue: false hasContentIssue false
  • English
  • Français

Genesis of Dioctahedral Phyllosilicates During Hydrothermal Alteration of Volcanic Rocks: I. The Golden Cross Epithermal Ore Deposit, New Zealand

Published online by Cambridge University Press:  28 February 2024

David A. Tillick ,
Donald R. Peacor  and
Jeffrey L. Mauk
David A. Tillick*
Affiliation:
Department of Geology, The University of Auckland, Private Bag 92019, Auckland, New Zealand
Donald R. Peacor
Affiliation:
Department of Geological Sciences, The University of Michigan, Ann Arbor, Michigan 48109-1063, USA
Jeffrey L. Mauk
Affiliation:
Department of Geology, The University of Auckland, Private Bag 92019, Auckland, New Zealand
*
E-mail of corresponding author: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

To characterize the evolution of dioctahedral interstratified clay minerals in the Golden Cross epithermal deposit, New Zealand, hydrothermally altered volcanic rocks containing the sequence smectite through illite-smectite (I-S) to muscovite were examined by optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission and analytical electron microscopies (TEM/AEM).

XRD analyses of 30 oriented clay samples show a broad deposit-wide trend of increasing illite content in I-S with increasing depth and proximity to the central vein system. Six representative samples were selected for SEM/TEM study on the basis of petrographic observations and XRD estimates of I-S interstratification. Ca and Na are the dominant interlayer cations in smectite, but as the proportion of illite layers in I-S increases, so does the K content and (IVAl + VIAl)/Si ratio. Layers and packets tend to flatten and form larger arrays, reducing the amount of pore space. Smectite coexists with (R = 1) I-S, rather than being (R = 0) I-S where R is the Reichweite parameter. The highest alteration rank samples contain discrete packets of mica to ∼300 Å thick, but a limited chemical and structural gap exists between illite, which is intermediate in composition between common illite and muscovite, and illite-rich I-S. Selected-area electron diffraction (SAED) patterns of mica show that the 1M polytype dominates, rather than the common 2M1 polytype.

Petrographic, SEM, and TEM data imply that all phyllosilicates formed via neoformation directly from fluids. Relatively mature I-S and micas form simultaneously, without progressing through the series of transformations that are commonly assumed to characterize diagenetic sequences during burial metamorphism in mud-dominated basins. Although the overall distribution of clay minerals is consistent with temperature as a controlling variable, local heterogeneities in the distribution of clay minerals were controlled by water/rock ratio, which varied widely owing to different rock types and fracture control.

Keywords

1M polytypeDioctahedral Clay MineralsEpithermalHydrothermal AlterationIllite-Smectite (I-S)NeoformationSmectiteTransmission Electron Microscopy (TEM)Volcanic Rocks
Type
Research Article
Information
Clays and Clay Minerals , Volume 49 , Issue 2 , April 2001 , pp. 126 - 140
Copyright
Copyright © 2001, The Clay Minerals Society

References

Adams, C.J. Graham, I.J. Seward, D. and Skinner, D.N.B., 1994 Geochronological and geochemical evolution of the late Cenozoic volcanism of the Coromandel Peninsula, New Zealand New Zealand Journal of Geology and Geophysics 37 359–379 10.1080/00288306.1994.9514626.CrossRefGoogle Scholar
Ahn, J.H. and Peacor, D.R., 1986 Transmission and analytical electron microscopy of the smectite-illite transition Clays and Clay Minerals 34 165–179 10.1346/CCMN.1986.0340207.Google Scholar
Ahn, J.H. and Peacor, D.R., 1987 Kaolinitization of biotite: TEM data and implications for an alteration mechanism American Mineralogist 72 353–356.Google Scholar
Altaner, S.P. and Ylagan, R.F., 1997 Comparison of structural models of mixed-layer illite/smectite and reaction mechanisms of smectite illitization Clays and Clay Minerals 45 517–533 10.1346/CCMN.1997.0450404.CrossRefGoogle Scholar
Bethke, C.M. Vergo, N. and Altaner, S.P., 1986 Pathways of smectite illitization Clays and Clay Minerals 34 125–135 10.1346/CCMN.1986.0340203.CrossRefGoogle Scholar
Brathwaite, R.L. and Christie, A.B., 1996 Geology of the Waihi Area - 1:50,000 Geological Map 21. New Zealand, 1 sheet Institute of Geological and Nuclear Sciences.Google Scholar
Brathwaite, R.L. Christie, A.B. Skinner, D.N.B. and Kear, D., 1989 The Hauraki Goldfield-regional setting, mineralisation and recent exploration. I Mineral Deposits of New Zealand Lower Hutt, New Zealand New Zealand Geological Survey 45–56.Google Scholar
Christidis, G.E., 1995 Mechanism of illitization of bentonites in the geothermal field of Milos Island Greece: Evidence based on mineralogy, chemistry, particle thickness and morphology Clays and Clay Minerals 43 569–585 10.1346/CCMN.1995.0430507.CrossRefGoogle Scholar
de Ronde, C.E.J. and Blattner, P., 1988 Hydrothermal alteration, stable isotopes, and fluid inclusions of the Golden Cross epithermal gold-silver deposit, Waihi, New Zealand Economic Geology 83 895–917 10.2113/gsecongeo.83.5.895.CrossRefGoogle Scholar
Dong, H. Peacor, D.R. and Freed, R.L., 1997 Phase relations among smectite, R1 illite-smectite, and illite American Mineralogist 82 379–391 10.2138/am-1997-3-416.CrossRefGoogle Scholar
Essene, E.J. and Peacor, D.R., 1995 Clay mineral thermometry — A critical perspective Clays and Clay Minerals 43 540–553 10.1346/CCMN.1995.0430504.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
Hayba, D.O. Bethke, P.M. Foley, N.K., Berger, B.R. and Bethke, R.M., 1985 Geologic, mineralogie, and geochemical characteristics of volcanic-hosted epithermal precious-metal deposits. I Reviews in Economic Geology, Volume 2: Geology and Geochemistry of Epithermal Systems Chelsea, Michigan Society of Economic Geologists 129–167.Google Scholar
Henley, R.W., Berger, B.R. and Bethke, P.M., 1985 The geothermal framework for epithermal systems. I Reviews in Economic Geology, Volume 2: Geology and Geochemistry of Epithermal Systems Chelsea, Michigan Society of Economic Geologists 1–24.Google Scholar
Henley, R.W. and Ellis, A.J., 1983 Geothermal systems ancient and modern: A geochemical review Earth Science Reviews 19 1–50 10.1016/0012-8252(83)90075-2.CrossRefGoogle Scholar
Hower, J. Eslinger, E.V. Hower, M.E. and Perry, E.A., 1976 Mechanism of burial metamorphism of argillaceous sediments: Mineralogical and chemical evidence Geological Society of America Bulletin 87 725–737 10.1130/0016-7606(1976)87<725:MOBMOA>2.0.CO;2.2.0.CO;2>CrossRefGoogle Scholar
Inoue, A. and Utada, M., 1983 Further investigations of a conversion series of dioctahedral mica/smectites in the Shinzan hydrothermal alteration area, Northeast Japan Clays and Clay Minerals 31 401–412 10.1346/CCMN.1983.0310601.CrossRefGoogle Scholar
Inoue, A. Minato, H. and Utada, M., 1978 Mineralogical properties and occurrence of illite/montmorillonite mixed layer clay minerals formed from Miocene volcanic glass in Waga-Omono district Clay Science 5 123–136.Google Scholar
Inoue, A. Kohyama, N. Kitagawa, R. and Watanabe, T., 1987 Chemical and morphological evidence for the conversion of smectite to illite Clay and Clay Minerals 35 111–120 10.1346/CCMN.1987.0350203.CrossRefGoogle Scholar
Jiang, W.-T. Peacor, D.R. and Slack, J.F., 1992 Microstructures, mixed-layering, and polymorphism of chlorite and retrograde berthierine in the Kidd Creek massive sulfide deposit, Ontario Clays and Clay Minerals 40 501–514 10.1346/CCMN.1992.0400503.CrossRefGoogle Scholar
Kim, J.-W. Peacor, D.R. Tessier, D. and Elsass, E., 1995 A technique for maintaining texture and permanent expansion of smectite interlayers for TEM observations Clays and Clay Minerals 43 51–57 10.1346/CCMN.1995.0430106.CrossRefGoogle Scholar
Li, G. Peacor, D.R. and Coombs, D.S., 1997 Transformation of smectite to illite in bentonite and associated sediments from Kaka Point, New Zealand: Contrast in rate and mechanism Clays and Clay Minerals 45 54–67 10.1346/CCMN.1997.0450106.CrossRefGoogle Scholar
Masuda, H. O’Neil, J.R. Jiang, W.-T. and Peacor, D.R., 1996 Relation between interlayer composition of authi-genic smectite, mineral assembalges, I-S reaction rate and fluid composition in silicic ash of the Nankai Trough Clays and Clay Minerals 44 443–459 10.1346/CCMN.1996.0440402.CrossRefGoogle Scholar
Moore, D.M. and Reynolds, R.C., 1997 X-ray Diffraction and the Identification and Analysis of Clay Minerals 2nd edition New York Oxford University Press.Google Scholar
Morse, J.W. and Casey, W.H., 1988 Ostwald processes and mineral paragenesis in sediments American Journal of Science 288 537–560 10.2475/ajs.288.6.537.CrossRefGoogle Scholar
Morton, J.P., 1985 Rb-Sr evidence for punctuated illite/smectite diagenesis in the Oligocene Frio Formation, Texas Gulf Coast Geological Society of America Bulletin 96 114–122 10.1130/0016-7606(1985)96<114:REFPID>2.0.CO;2.2.0.CO;2>CrossRefGoogle Scholar
Niu, B. Yoshimura, T. and Hirai, A., 2000 Smectite dia-genesis in Neogene marine sandstone and mudstone of the Niigata Basin, Japan Clays and Clay Minerals 48 26–42 10.1346/CCMN.2000.0480104.CrossRefGoogle Scholar
Ohr, M. Halliday, A.N. and Peacor, D.R., 1991 Sr and Nd isotopic evidence for punctuated clay diagenesis, Texas Gulf Coast Earth and Planetary Science Letters 105 110–126 10.1016/0012-821X(91)90124-Z.CrossRefGoogle Scholar
Patrier, P. Papapanagiotou, P. Beaufort, D. Traineau, H. Bril, H. and Rojas, J., 1996 Role of permeability versus temperature in the distribution of the fine (<0.2 μm) clay fraction in the Chipilapa geothermal system (El Salvador, Centrai America) Journal of Volcanology and Geothermal Research 72 101–120 10.1016/0377-0273(95)00078-X.CrossRefGoogle Scholar
Peacor, D.R., 1992 Analytical electron microscopy: X-ray analysis. I Reviews in Mineralogy, Volume 27, Minerals and Reactions at the Atomic Scale, Transmission Electron Microscopy 27 113–140 10.1515/9781501509735-008.CrossRefGoogle Scholar
Reyes, A.G., 1990 Petrology of Philippine geothermal systems and the application of alteration mineralogy to their assessment Journal of Volcanology and Geothermal Research 43 279–309 10.1016/0377-0273(90)90057-M.CrossRefGoogle Scholar
Reynolds, R.C. Jr., 1985 NEWMOD — A Computer Program for the Calculation of One-Dimensional Diffraction Profiles of Clays Hanover, New Hampshire Published by the author, 8 Brook Road.Google Scholar
Schoen, R., White, D.E. and Hemley, J.J. (1974) Argilliza-tion by descending acid at the Steamboat Springs, Nevada. Clays and Clay Minerals, 22, 1—22.CrossRefGoogle Scholar
Simpson, M.P. Simmons, S.F. Mauk, J.L. McOnie, A., Mauk, J.L. and St George, J.D., 1995 The distribution of hydrothermal alteration minerals at the Golden Cross epithermal Au-Ag deposit, Waihi, New Zealand. I Pacrim Congress ’95 New Zealand Australasian Institute of Mining and Metallurgy 551–556.Google Scholar
Simpson, M.P., Mauk, J.L. and Simmons, S.E. (1998) The occurrence, distribution and XRD properties of hydrothermal clays at the Golden Cross epithermal Au−Ag deposit, New Zealand. I. Proceedings of the 20th New Zealand Geothermal Workshop, Auckland, New Zealand, Simmons, S.E., ed., Auckland University Geothermal Institute, New Zealand, 215–220.Google Scholar
Skinner, D.N.B. and Smith, I.E.M., 1986 Neogene volcanism of the Hauraki Volcanic Region. I Late Cenozoic Volcanism in New Zealand New Zealand Royal Society of New Zealand Bulletin 23 21–47.Google Scholar
Tillick, D.A. Mauk, J.L. and Peacor, D.R., 1999 SEM and TEM investigations of a dioctahedral clay mineral series in the Golden Cross epithermal deposit, New Zealand: Preliminary results. I New Zealand Australasian Institute of Mining and Metallurgy 131–140.Google 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
Yan, Y. Tillick, D.A. Peacor, D.R. and Simmons, S.F., 2001 Genesis of dioctahedral phyllosilicates during hydrothermal alteration of volcanic rocks: II. The Broadlands-Ohaaki hydrothermal system. New Zealand Clays and Clay Minerals 49 141–155 10.1346/CCMN.2001.0490204.CrossRefGoogle Scholar
Yau, Y.-C. Peacor, D.R. and McDowell, S.G., 1987 Smectite-to-illite reactions in Salton Sea shales: A transmission and analytical electron microscopy study Journal of Sedimentary Petrology 57 335–342.Google Scholar