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<title>UTas ePrints - Mineralogical and Isotopic Zonation in the Sur-Sur Tourmaline Breccia, Rio Blanco-Los Bronces Cu-Mo Deposit, Chile: Implications for Ore Genesis</title>
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<meta content="Cooke, D.R." name="eprints.creators_name" />
<meta content="Walshe, J.L." name="eprints.creators_name" />
<meta content="Archibald, D.A." name="eprints.creators_name" />
<meta content="Skarmeta, J." name="eprints.creators_name" />
<meta content="Serrano, L." name="eprints.creators_name" />
<meta content="Vargas, R." name="eprints.creators_name" />
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<meta content="Mineralogical and Isotopic Zonation in the Sur-Sur Tourmaline Breccia, Rio Blanco-Los Bronces Cu-Mo Deposit, Chile: Implications for Ore Genesis" name="eprints.title" />
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<meta content="The Sur-Sur tourmaline breccia is located in the southeast part of the Rio Blanco-Los Bronces porphyry copper-
molybdenum deposit, central Chile. The breccia hosts approximately one-quarter of the total resource of
57 Mt of fine copper at Rio Blanco. The breccia is hosted within, and contains altered clasts of, granodiorite
from the 12 to 8 Ma San Francisco batholith, which intruded a sequence of Miocene volcanic and volcaniclastic
rocks. A series of weakly mineralized to barren felsic porphyries cut the breccia and indicate a minimum
age of approximately 6 Ma for mineralization at Sur-Sur.
The Sur-Sur breccia dike is at least 3 km long, 0.2 km wide, and has a vertical extent of at least 1 km. The
breccia has been cemented by early biotite and anhydrite at depth and by tourmaline and specularite at higher
altitudes. These early-formed cements have been overgrown and in some cases replaced by chalcopyrite, magnetite,
pyrite, and quartz. Mineralogical zonation in the breccia includes a transition from biotite cement and
related biotite alteration upward to tourmaline cement and quartz-sericite-tourmaline alteration at approximately
3,000-m elevation. Iron-oxide minerals are also zoned, with a transition upward from a magnetite-dominated
zone below 3,330 m to a specularite-dominated zone above 3,600 m. Pyrite is the dominant sulfide at
altitudes above 4,000 m.
Secondary liquid-rich, vapor-rich, and hypersaline fluid inclusions are preserved in quartz and tourmaline
cement. Measured homogenization temperatures are mostly between 300 degrees and 450 degrees C, and salinities range from 0 to 69 wt percent NaCl equiv. Sulfur isotope compositions of sulfide cement range from -4.1 to +2.7 per mil.
The lowest delta 34S(sulfide) values are in samples from between 3,700- and 4,000-m elevation, where they correspond
to the highest copper grades in the tourmaline breccia. This high-grade zone also contains abundant specularite
(locally replaced by magnetite). Modeling of sulfate-sulfide equilibrium indicate that approximately 150 degrees C of cooling over a vertical interval of 100 m would be required to account for the zonation of sulfide isotope
compositions at Sur-Sur, making conductive cooling an unlikely ore-forming mechanism.
Measured 206Pb/204Pb values of lead in anhydrite cement in the Sur-Sur tourmaline breccia and the Rio
Blanco magmatic breccia range from 17.558 to 18.479. 207Pb/204Pb values range from 15.534 to 15.623, and
208Pb/204Pb values range from 37.341 to 38.412. The lead in anhydrite is considerably less radiogenic than that
indicated by values obtained previously for lead in sulfide ores and igneous host rocks at Rio Blanco-Los
Bronces. The source of lead in anhydrite must have been from rocks external to the main magmatichydrothermal
system, probably the Precordilleran basement.
A magmatic-hydrothermal explosion from a deep-seated crystallizing intrusion triggered breccia formation
at Sur-Sur. Hydrostatic pressures catastrophically exceeded lithostatic load plus the tensile strength of the confining
granodiorite, leading to widespread brecciation and subsequent invasion by large volumes of magmatic
gas and hypersaline brine. The low-density gas phase (carrying H2O, SO2, HCl, and B2O3) separated physically
from the dense copper-bearing brine and flushed through the breccia column first, where it condensed into
ground waters of uncertain derivation. Anhydrite, specularite, and tourmaline were deposited from this lowsalinity,
acidic, oxidized hybrid solution. Subsequent upwelling of magmatic-hydrothermal brine resulted in
sulfide deposition. High-grade copper deposition is interpreted to have occurred in response to mixing of the
oxidized, acidic water with the copper-bearing magmatic-hydrothermal brine." name="eprints.abstract" />
<meta content="2005" name="eprints.date" />
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<meta content="Economic Geology" name="eprints.publication" />
<meta content="100" name="eprints.volume" />
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<meta content="Bastrakov, E., Shvarov, Y., Girvan, S., Cleverley, J., and Wyborn, L., 2004,FreeGs: Web-enabled thermodynamic database for modelling of geochemical processes [abs.]: Geological Society of Australia Abstracts, v. 73, p. 52.
Bodnar, R.J., Burnham, C.W., and Sterner, S.M., 1985, Synthetic inclusions in natural quartz. III. Determination of phase equilibrium properties in the system H2O-NaCl to 1000 degrees C and 1500 bars: Geochimica et Cosmochimica
Acta, v. 49, p. 1861-1873.
Bodnar, R.J., Sterner, S.M., and Hall, D.L., 1989, Salty: A FORTRAN program to calculate compositions of fluid inclusions in the system NaCl-KCl-H2O: Computers and Geosciences, v. 15, p. 19-41.
Burnham, C.W., 1979, Magmas and hydrothermal fluids, in H. L. Barnes, ed., Geochemistry of hydrothermal ore deposits, 2nd ed.: New York, John Wiley and Sons, p. 71-136.
-1985, Energy release in subvolcanic environments: Implications for breccia formation: ECONOMIC GEOLOGY, v. 80, p. 1515-1522.
Camus, F., 2002, The Andean porphyry systems: University of Tasmania, Centre for Ore Deposit Research Special Publication 4, p. 5-22.
Cannell, J.B., 2004, El Teniente porphyry copper-molybdenum deposit, central Chile: Unpublished PhD thesis, Australia, University of Tasmania, 341 p.
Cloke, P.L., and Kesler, S.E., 1979, The halite trend in hydrothermal systems: ECONOMIC GEOLOGY, v. 74, p. 1823-1831.
Davidson, P., and Kamenetsky, V. S., 2001, Immiscibility and continuous melt-fluid evolution within the RiÂÂÂo Blanco porphyry system, Chile: Evidence from inclusions in magmatic quartz: ECONOMIC GEOLOGY, v. 96, p.1921-1929.
Davidson, J.P., Harmon, R.S., and Worner, G., 1991, The source of central Andean magmas: Some considerations: Geological Society of America Special Paper 265, p. 233-244.
Davidson, P., Kamenetsky, V.S., Cooke, D.R., Frikken, P., Hollings, P., Ryan, C, Van Achterbergh, E., Mernagh, T., Skarmeta, J., Serrano, L., and Vargas, R, 2005, Magmatic precursors of hydrothermal fluids at the Rio Blanco Cumolybdenum deposit, Chile: Links to silicate magmas and metal transport: ECONOMIC GEOLOGY, v. 100, p. 963-978.
Deckart, K., Clark, A.H., Aquilar, C., and Vargas, R, 2005, Magmatic and hydrothermal chronology of the supergiant Rio Blanco porphyry copper deposit, central Chile: Implications of an integrated U-Pb and 40Ar-39Ar database:
ECONOMIC GEOLOGY, v. 100, p. 905-934.
Fournier, R.O., 1999, Hydrothermal processes related to movement of fluid from plastic into brittle rock in the magmatic-epithermal environment: ECONOMIC GEOLOGY, vol. 94, 8, p. 1193-1211.
Frikken, P.H., 2004, Breccia-hosted copper-molybdenum mineralization at Rio Blanco, Chile: Unpublished PhD thesis, Australia, University of Tasmania, 290 p.
Garofalo, P., Audetat, A., Gunther, D., Heinrich, C.A., and Ridley, J., 2000, Estimation and testing of standard molar thermodynamic properties of tourmaline end-members using data of natural samples: American Mineralogist,
v. 85, p. 78-88.
Gustafson, L.B., and Hunt, J.P., 1975, The porphyry copper deposit at El Salvador, Chile: ECONOMIC GEOLOGY, v. 70, p. 857-912.
Henley, R.W., and McNabb, A., 1978, Magmatic vapor plumes and groundwater interaction in porphyry copper emplacement: ECONOMIC GEOLOGY, v. 73, p. 1-20.
Hildreth, W., and Moorbath, S., 1988, Crustal contributions to arc magmatism in the Andes of central Chile: Contributions to Mineralogy and Petrology, v. 98, p. 455-498.
Hollings, P., Cooke, D., and Clark, A., 2005, Regional geochemistry of Tertiary igneous rocks in Central Chile: Implications for the geodynamic environment of giant porphyry copper and epithermal gold mineralization:
ECONOMIC GEOLOGY, v. 100, p. 887-904.
Holmgren, C., Marti, M., Skewes, M.A., Schneider, A., and Harmon, R., 1988, Analisis isotopicos y de inclusiones fluidas en el yacimiento Los Bronces, Chile central: Congreso Geologico Chileno, no. 5, Actas, v. 1, p.
B299-B314.
Huston, D.L., Power, M., and Large, R.R., 1993, Laser-ablation analysis of sulfur isotopes: An analytical technique now available in Australia [abs]: Geological Society of Australia Abstracts v. 10, p. 30-31.
Johnson, J.W., Oelkers, E.H., and Helgeson, H.C., 1992, SUPCRT92: A software package for calculating the standard molal thermodynamic properties of minerals, gases, aqueous species and reactions from 1 to 5000 bars and
0 degrees to 1000 degrees C: Computers and Geosciences, v. 18, p. 899-947.
Kay, S.M., and Ambruzzi, J.M., 1996, Magmatic evidence for Neogene lithospheric evolution of the central Andean flat slab between 30-32 degrees south: Tectonophysics, v. 259, p. 15-28.
Kay, S.M., Mpodozis, C., and Coira, B., 1999, Neogene magmatism, tectonism and mineral deposits of the central Andes: Society of Economic Geologists Special Publication 7, p. 7-59.
Kusakabe, M., Nakagawa, S., Hori, M., Matsihisa, Y., Ojeda, J.M., and Serrano, L., 1984, Oxygen and sulphur isotopic compositions of quartz, anhydrite, and sulfide minerals from the El Teniente and Rio Blanco porphyry
copper deposits, Chile: Bulletin of the Geological Survey of Japan, v. 35, p. 583-614.
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biotite: University of Western Australia Publication 2, p. 244-259.
Ohmoto, H., and Goldhaber, M.B., 1997, Sulfur and carbon isotopes, in Barnes, H.L., ed., Geochemistry of hydrothermal ore deposits, 3rd ed.: New
York, John Wiley and Sons, p. 517-611.
Potter, R.W.I, Clynne, M.A., and Brown, D.L., 1978, Freezing point depression of aqueous sodium chloride solutions: ECONOMIC GEOLOGY, v. 73, p.284-285.
Puig, A., 1988, Geologic and metallogenic significance of the isotopic composition of lead in galenas of the Chilean Andes: ECONOMIC GEOLOGY, v. 83, p. 843-858.
Quirt, S., Clark, A.H., Farrar, E., and Sillitoe, R.H., 1971, Potassium-argon ages of porphyry copper deposits in northern and central Chile [abs.]: Geological
Society of America Abstracts with Programs, no. 3, p. 676-677.
Rae, A.J., Cooke, D.R., Phillips, D., Yeats, C., Ryan, C., and Hermoso, D.,2003. Spatial and temporal relationships between hydrothermal alteration assemblages at the Palinpinon geothermal field, Philippines: Implications
for porphyry and epithermal ore deposits: Society of Economic Geologists Special Publication 10, p. 223-246.
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Roedder, E., 1984, Fluid inclusions: Reviews in Mineralogy, v. 12, 644 p.
Rye, R.O., 1993, The evolution of magmatic fluids in the epithermal environment: the stable isotope perspective: ECONOMIC GEOLOGY, v. 88, p. 733-753
Serrano, L., Vargas, R., Stambuk, V., Aguilar, C., Galeb, M., Holmgren, C., Contreras, A., Godoy, S., Vela, I., Skewes, A.M., and Stern, C.R., 1996, The late Miocene to early Pliocene RiÂÂÂo Blanco-Los Bronces copper deposit,
central Chilean Andes: Society of Economic Geologists Special Publication 5, p.119-130.
Skewes, M.A., and Holmgren, C., 1993, Solevantamiento andino, erosion y emplazamiento de brechas mineralizadas en el deposito de cobre porfoÂÂÂdico
Los Bronces, chile central (33 degrees S): aplicacion de geothermometria de inclusiones fluidas: Revista Geologica de Chile, v. 20, p. 71-83.
Skewes, M.A., and Stern, C.R., 1996, Late Miocene mineralized breccias in the Andes of central Chile: Sr and Nd isotopic evidence for multiple magmatic sources: Society of Economic Geologists Special Publication 5, p.
119-130.
Skewes, M.A., Holmgren, C., and Stern, C.R., 2003, The Donoso copperrich, tourmaline-bearing breccia pipe in central Chile: Petrologic, fluid inclusion
and stable isotope evidence for an origin from magmatic fluids: Mineralium Deposita, v. 38, p. 2-21.
Tilton, G.R., 1979, Isotopic studies of Cenozoic Andean calc-alkaline rocks: Year Book - Carnegie Institution of Washington Yearbook 78, p. 298-303.
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-2003, Lead sources in Mesozoic and Cenozoic Andean ore deposits: North-central Chile (30 degrees S): Mineralium Deposita, v. 38, p. 234-250.
Vargas, R., Gustafson, L.B., Vukasovic, M, Tidy, E., and Skewes, A., 1999, Ore breccias in the RiÂÂÂo Blanco-Los Bronces porphyry copper deposit, Chile: Society of Economic Geologists Special Publication 7, p.281-297.
Vergara, M., Charrier, R., Munizaga, F., Rivano, S, Sepulveda, P., Thiele, R., and Drake, R., 1988, Miocene volcanism in the central Chilean Andes (31 degrees 30S-34 degrees 35S): Journal of South American Earth Sciences, v.1,
p.199-209.
Warnaars, F.W., Holmgren, C.D., and Barassi, S., 1985, Porphyry copper and tourmaline breccias at RiÂÂÂo Blanco-Los Bronces, Chile: ECONOMIC GEOLOGY, v. 80, p. 1544-1565.
Zentilli, M., Doe, B., Hedge, C.E., Alvarez, C.E., Tidy, E., and Daroca, J.A., 1988, Isotopos de plomo en yacimientos de tipo porfido cupriÂÂÂfero comparados
con otros depositos metaliÂÂÂferos en los Andes del norte de Chile y Argentian: Congreso Geologico Chileno, 5th, Santiago, Augusto 8-12, Actas, p. B331-369.
" name="eprints.referencetext" />
<meta content="Frikken, P. and Cooke, D.R. and Walshe, J.L. and Archibald, D.A. and Skarmeta, J. and Serrano, L. and Vargas, R. (2005) Mineralogical and Isotopic Zonation in the Sur-Sur Tourmaline Breccia, Rio Blanco-Los Bronces Cu-Mo Deposit, Chile: Implications for Ore Genesis. Economic Geology, 100 (5). pp. 935-961. ISSN 0361-0128" name="eprints.citation" />
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<meta content="Cooke, D.R." name="DC.creator" />
<meta content="Walshe, J.L." name="DC.creator" />
<meta content="Archibald, D.A." name="DC.creator" />
<meta content="Skarmeta, J." name="DC.creator" />
<meta content="Serrano, L." name="DC.creator" />
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<meta content="The Sur-Sur tourmaline breccia is located in the southeast part of the Rio Blanco-Los Bronces porphyry copper-
molybdenum deposit, central Chile. The breccia hosts approximately one-quarter of the total resource of
57 Mt of fine copper at Rio Blanco. The breccia is hosted within, and contains altered clasts of, granodiorite
from the 12 to 8 Ma San Francisco batholith, which intruded a sequence of Miocene volcanic and volcaniclastic
rocks. A series of weakly mineralized to barren felsic porphyries cut the breccia and indicate a minimum
age of approximately 6 Ma for mineralization at Sur-Sur.
The Sur-Sur breccia dike is at least 3 km long, 0.2 km wide, and has a vertical extent of at least 1 km. The
breccia has been cemented by early biotite and anhydrite at depth and by tourmaline and specularite at higher
altitudes. These early-formed cements have been overgrown and in some cases replaced by chalcopyrite, magnetite,
pyrite, and quartz. Mineralogical zonation in the breccia includes a transition from biotite cement and
related biotite alteration upward to tourmaline cement and quartz-sericite-tourmaline alteration at approximately
3,000-m elevation. Iron-oxide minerals are also zoned, with a transition upward from a magnetite-dominated
zone below 3,330 m to a specularite-dominated zone above 3,600 m. Pyrite is the dominant sulfide at
altitudes above 4,000 m.
Secondary liquid-rich, vapor-rich, and hypersaline fluid inclusions are preserved in quartz and tourmaline
cement. Measured homogenization temperatures are mostly between 300 degrees and 450 degrees C, and salinities range from 0 to 69 wt percent NaCl equiv. Sulfur isotope compositions of sulfide cement range from -4.1 to +2.7 per mil.
The lowest delta 34S(sulfide) values are in samples from between 3,700- and 4,000-m elevation, where they correspond
to the highest copper grades in the tourmaline breccia. This high-grade zone also contains abundant specularite
(locally replaced by magnetite). Modeling of sulfate-sulfide equilibrium indicate that approximately 150 degrees C of cooling over a vertical interval of 100 m would be required to account for the zonation of sulfide isotope
compositions at Sur-Sur, making conductive cooling an unlikely ore-forming mechanism.
Measured 206Pb/204Pb values of lead in anhydrite cement in the Sur-Sur tourmaline breccia and the Rio
Blanco magmatic breccia range from 17.558 to 18.479. 207Pb/204Pb values range from 15.534 to 15.623, and
208Pb/204Pb values range from 37.341 to 38.412. The lead in anhydrite is considerably less radiogenic than that
indicated by values obtained previously for lead in sulfide ores and igneous host rocks at Rio Blanco-Los
Bronces. The source of lead in anhydrite must have been from rocks external to the main magmatichydrothermal
system, probably the Precordilleran basement.
A magmatic-hydrothermal explosion from a deep-seated crystallizing intrusion triggered breccia formation
at Sur-Sur. Hydrostatic pressures catastrophically exceeded lithostatic load plus the tensile strength of the confining
granodiorite, leading to widespread brecciation and subsequent invasion by large volumes of magmatic
gas and hypersaline brine. The low-density gas phase (carrying H2O, SO2, HCl, and B2O3) separated physically
from the dense copper-bearing brine and flushed through the breccia column first, where it condensed into
ground waters of uncertain derivation. Anhydrite, specularite, and tourmaline were deposited from this lowsalinity,
acidic, oxidized hybrid solution. Subsequent upwelling of magmatic-hydrothermal brine resulted in
sulfide deposition. High-grade copper deposition is interpreted to have occurred in response to mixing of the
oxidized, acidic water with the copper-bearing magmatic-hydrothermal brine." name="DC.description" />
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<h1 class="ep_tm_pagetitle">Mineralogical and Isotopic Zonation in the Sur-Sur Tourmaline Breccia, Rio Blanco-Los Bronces Cu-Mo Deposit, Chile: Implications for Ore Genesis</h1>
<p style="margin-bottom: 1em" class="not_ep_block"><span class="person_name">Frikken, P.</span> and <span class="person_name">Cooke, D.R.</span> and <span class="person_name">Walshe, J.L.</span> and <span class="person_name">Archibald, D.A.</span> and <span class="person_name">Skarmeta, J.</span> and <span class="person_name">Serrano, L.</span> and <span class="person_name">Vargas, R.</span> (2005) <xhtml:em>Mineralogical and Isotopic Zonation in the Sur-Sur Tourmaline Breccia, Rio Blanco-Los Bronces Cu-Mo Deposit, Chile: Implications for Ore Genesis.</xhtml:em> Economic Geology, 100 (5). pp. 935-961. ISSN 0361-0128</p><p style="margin-bottom: 1em" class="not_ep_block"></p><table style="margin-bottom: 1em" class="not_ep_block"><tr><td valign="top" style="text-align:center"><a href="http://eprints.utas.edu.au/1991/1/Frikken%2C_Cooke_et_al_ECON_GEOL_2005.pdf"><img alt="[img]" src="http://eprints.utas.edu.au/style/images/fileicons/application_pdf.png" border="0" class="ep_doc_icon" /></a></td><td valign="top"><a href="http://eprints.utas.edu.au/1991/1/Frikken%2C_Cooke_et_al_ECON_GEOL_2005.pdf"><span class="ep_document_citation">PDF</span></a> - Full text restricted - Requires a PDF viewer<br />2145Kb</td><td><form method="get" accept-charset="utf-8" action="http://eprints.utas.edu.au/cgi/request_doc"><input value="2466" name="docid" accept-charset="utf-8" type="hidden" /><div class=""><input value="Request a copy" name="_action_null" class="ep_form_action_button" onclick="return EPJS_button_pushed( '_action_null' )" type="submit" /> </div></form></td></tr></table><p style="margin-bottom: 1em" class="not_ep_block">Official URL: <a href="http://dx.doi.org/10.2113/100.5.935">http://dx.doi.org/10.2113/100.5.935</a></p><div class="not_ep_block"><h2>Abstract</h2><p style="padding-bottom: 16px; text-align: left; margin: 1em auto 0em auto">The Sur-Sur tourmaline breccia is located in the southeast part of the Rio Blanco-Los Bronces porphyry copper-
molybdenum deposit, central Chile. The breccia hosts approximately one-quarter of the total resource of
57 Mt of fine copper at Rio Blanco. The breccia is hosted within, and contains altered clasts of, granodiorite
from the 12 to 8 Ma San Francisco batholith, which intruded a sequence of Miocene volcanic and volcaniclastic
rocks. A series of weakly mineralized to barren felsic porphyries cut the breccia and indicate a minimum
age of approximately 6 Ma for mineralization at Sur-Sur.
The Sur-Sur breccia dike is at least 3 km long, 0.2 km wide, and has a vertical extent of at least 1 km. The
breccia has been cemented by early biotite and anhydrite at depth and by tourmaline and specularite at higher
altitudes. These early-formed cements have been overgrown and in some cases replaced by chalcopyrite, magnetite,
pyrite, and quartz. Mineralogical zonation in the breccia includes a transition from biotite cement and
related biotite alteration upward to tourmaline cement and quartz-sericite-tourmaline alteration at approximately
3,000-m elevation. Iron-oxide minerals are also zoned, with a transition upward from a magnetite-dominated
zone below 3,330 m to a specularite-dominated zone above 3,600 m. Pyrite is the dominant sulfide at
altitudes above 4,000 m.
Secondary liquid-rich, vapor-rich, and hypersaline fluid inclusions are preserved in quartz and tourmaline
cement. Measured homogenization temperatures are mostly between 300 degrees and 450 degrees C, and salinities range from 0 to 69 wt percent NaCl equiv. Sulfur isotope compositions of sulfide cement range from -4.1 to +2.7 per mil.
The lowest delta 34S(sulfide) values are in samples from between 3,700- and 4,000-m elevation, where they correspond
to the highest copper grades in the tourmaline breccia. This high-grade zone also contains abundant specularite
(locally replaced by magnetite). Modeling of sulfate-sulfide equilibrium indicate that approximately 150 degrees C of cooling over a vertical interval of 100 m would be required to account for the zonation of sulfide isotope
compositions at Sur-Sur, making conductive cooling an unlikely ore-forming mechanism.
Measured 206Pb/204Pb values of lead in anhydrite cement in the Sur-Sur tourmaline breccia and the Rio
Blanco magmatic breccia range from 17.558 to 18.479. 207Pb/204Pb values range from 15.534 to 15.623, and
208Pb/204Pb values range from 37.341 to 38.412. The lead in anhydrite is considerably less radiogenic than that
indicated by values obtained previously for lead in sulfide ores and igneous host rocks at Rio Blanco-Los
Bronces. The source of lead in anhydrite must have been from rocks external to the main magmatichydrothermal
system, probably the Precordilleran basement.
A magmatic-hydrothermal explosion from a deep-seated crystallizing intrusion triggered breccia formation
at Sur-Sur. Hydrostatic pressures catastrophically exceeded lithostatic load plus the tensile strength of the confining
granodiorite, leading to widespread brecciation and subsequent invasion by large volumes of magmatic
gas and hypersaline brine. The low-density gas phase (carrying H2O, SO2, HCl, and B2O3) separated physically
from the dense copper-bearing brine and flushed through the breccia column first, where it condensed into
ground waters of uncertain derivation. Anhydrite, specularite, and tourmaline were deposited from this lowsalinity,
acidic, oxidized hybrid solution. Subsequent upwelling of magmatic-hydrothermal brine resulted in
sulfide deposition. High-grade copper deposition is interpreted to have occurred in response to mixing of the
oxidized, acidic water with the copper-bearing magmatic-hydrothermal brine.</p></div><table style="margin-bottom: 1em" border="0" cellpadding="3" class="not_ep_block"><tr><th valign="top" class="ep_row">Item Type:</th><td valign="top" class="ep_row">Article</td></tr><tr><th valign="top" class="ep_row">Keywords:</th><td valign="top" class="ep_row">porphyry copper radiogenic isotopes fluid mixing</td></tr><tr><th valign="top" class="ep_row">Subjects:</th><td valign="top" class="ep_row"><a href="http://eprints.utas.edu.au/view/subjects/260100.html">260000 Earth Sciences > 260100 Geology</a></td></tr><tr><th valign="top" class="ep_row">Collections:</th><td valign="top" class="ep_row">UNSPECIFIED</td></tr><tr><th valign="top" class="ep_row">ID Code:</th><td valign="top" class="ep_row">1991</td></tr><tr><th valign="top" class="ep_row">Deposited By:</th><td valign="top" class="ep_row"><span class="ep_name_citation"><span class="person_name">Mrs Katrina Keep</span></span></td></tr><tr><th valign="top" class="ep_row">Deposited On:</th><td valign="top" class="ep_row">26 Sep 2007</td></tr><tr><th valign="top" class="ep_row">Last Modified:</th><td valign="top" class="ep_row">23 Jan 2008 14:59</td></tr><tr><th valign="top" class="ep_row">ePrint Statistics:</th><td valign="top" class="ep_row"><a target="ePrintStats" href="/es/index.php?action=show_detail_eprint;id=1991;">View statistics for this ePrint</a></td></tr></table><p align="right">Repository Staff Only: <a href="http://eprints.utas.edu.au/cgi/users/home?screen=EPrint::View&eprintid=1991">item control page</a></p>
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