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  5.     <title>UTas ePrints - Fluid Chemistry, Structural Setting, and Emplacement History of the Rosario Cu-Mo Porphyry and Cu-Ag-Au Epithermal Veins, Collahuasi District, Northern Chile</title>
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  13.     <meta content="Masterman, G.J." name="eprints.creators_name" />
  14. <meta content="Cooke, D.R." name="eprints.creators_name" />
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  17. <meta content="Lee, A.W." name="eprints.creators_name" />
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  29. <meta content="Fluid Chemistry, Structural Setting, and Emplacement History of the Rosario
  30. Cu-Mo Porphyry and Cu-Ag-Au Epithermal Veins, Collahuasi District, Northern Chile" name="eprints.title" />
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  32. <meta content="260100" name="eprints.subjects" />
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  34. <meta content="fluid inclusions structure telescoping high sulfidation" name="eprints.keywords" />
  35. <meta content="The Rosario Cu-Mo-Ag deposit is located in the Collahuasi district of northern Chile. It comprises high-grade
  36. Cu-Ag-(Au) epithermal veins, superimposed on the core of a porphyry Cu-Mo orebody. Rosario has mining reserves
  37. of 1,094 million metric tons (Mt) at 1.03 percent copper. An additional 1,022 Mt at 0.93 percent copper
  38. occurs in the district at the nearby Ujina and Quebrada Blanca porphyry deposits. The Rosario reserve contains
  39. over 95 percent hypogene ore, whereas supergene-sulfide ores dominate at Ujina and Quebrada Blanca.
  40. Mineralized veins are hosted within Lower Permian volcanic and sedimentary rocks, Lower Triassic granodiorite
  41. and late Eocene porphyritic quartz-monzonite. The Rosario fault system, a series of moderate southwest-
  42. dipping faults, has localized high-grade Cu-Ag-(Au) veins. At Cerro La Grande, similar high-grade Cu-
  43. Ag-(Au) veins are hosted in north-northeast-trending, sinistral wrench faults. Normal movement in the Rosario
  44. fault system is interpreted to have been synchronous with sinistral strike-slip deformation at La Grande.
  45. Hydrothermal alteration at Rosario is characterized by a K-feldspar core, focused in the Rosario Porphyry
  46. that grades out to a secondary biotite-albite-magnetite assemblage. Paragenetic relationships indicate that magnetite
  47. was the earliest formed alteration product but has been replaced by biotite-albite. Vein crosscutting relationships
  48. indicate that K-feldspar formed during and after biotite-albite alteration. Chalcopyrite and bornite
  49. were deposited in quartz veins associated with both K-feldspar and biotite-albite assemblages. The early hydrothermal
  50. fluid was a hypersaline brine (40-45 wt % NaCl) that coexisted with vapor between 400 degrees and
  51. >600 degrees C. Weakly mineralized illite-chlorite (intermediate argillic) alteration of the early K and Na silicate assemblages
  52. was caused by moderate temperature (250 degrees-350 degrees C), moderate-salinity brines (10-15 wt % NaCl).
  53. Molybdenite was precipitated in quartz veins that formed between the potassic and intermediate argillic alteration
  54. events. These fluids were 350 degrees to 400 degrees C with salinities between 10 and 15 wt percent NaCl.
  55. Porphyry-style ore and alteration minerals were overprinted by structurally controlled quartz-alunite-pyrite,
  56. pyrophyllite-dickite, and muscovite-quartz (phyllic) alteration assemblages. The quartz-alunite-pyrite alteration
  57. formed at 300 degrees to 400 degrees C from fluids with a salinity of 10 wt percent NaCl. The pyrophyllite-dickite assemblage
  58. formed between 250 degrees and 320 degrees C from dilute (5 wt % NaCl) fluids. An upward-flared zone of muscovite-
  59. quartz-pyrite altered rocks surrounds the fault-controlled domain of advanced argillic alteration. Thick
  60. veins (0.5-2 m wide) of fault-hosted massive pyrite, chalcopyrite, and bornite precipitated brines with a salinity
  61. of 30 wt percent NaCl at temperatures of 250 degrees to 300 degrees C.
  62. Pressure-depth estimates indicate that at least 1 km of rock was eroded at Rosario between formation of the
  63. K-Na silicate and advanced argillic assemblages. This erosion was rapid, occurring over a period of 1.8 m.y. The
  64. Rosario Porphyry intruded immediately after the Incaic tectonic phase, implying that it was emplaced as the
  65. Domeyko Cordillera underwent gravitational collapse, expressed as normal faults in the upper crust. Gravitational
  66. sliding potentially accelerated exhumation and helped to promote telescoping of the high-sulfidation environment
  67. onto the Rosario Porphyry.
  68. The hydrothermal system responsible for porphyry Cu mineralization at Rosario was partially exhumed prior
  69. to the formation of high-sulfidation ore and alteration assemblages. This implies that emplacement of a second
  70. blind intrusion occurred somewhere beneath the Rosario and Cerro La Grande high-sulfidation vein systems
  71. and is supported by the fault geometry and zoning of precious metals and sulfosalts at the district scale." name="eprints.abstract" />
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  83. <meta content="Ayllon, F., Bakker, R.J., and Warr, L.N., 2003, Re-equilibration of fluid inclusions in diagenetic-anchizonal rocks of the Cinera-Matallana coal basin (NW Spain): Geofluids, v. 3, p. 49-68.
  84. Arancibia, O.N., and Clark, A.H., 1996, Early magnetite-amphibole-plagioclase alteration-mineralization in the Island Copper porphyry copper-goldmolybdenum
  85. deposit, British Columbia: ECONOMIC GEOLOGY, v. 91, p.
  86. 402-438.
  87. Arribas, A., Jr., 1995, Characteristics of high-sulfidation epithermal deposits, and their relation to magmatic fluid: Mineralogical Association of Canada Short Course Series, v. 23, p. 419-454.
  88. Arribas, A. Jr., Hedenquist, J.W., Itaya, T., Okada, T., Concepcion, R.A., and Garcia, J.S.J., 1995, Contemporaneous formation of adjacent porphyry and epithermal Cu-Au deposits over 3000 Ka in northern Luzon, Philippines:
  89. Geology, v. 23, p. 337-340.
  90. Audetat, A., and Gunther, D., 1999, Mobility and H2O loss from inclusions in natural quartz crystals: Contributions to Mineralogy and Petrology, v. 137, p. 1-14.
  91. Bloom, M.S., 1981, Chemistry of inclusion fluids: Stockwork molybdenum deposits from Questa, New Mexico, and Hudson Bay Mountain and Endako, British Columbia: ECONOMIC GEOLOGY, v. 76, p. 1906-1920.
  92. Bodnar, R.J., 1994, Synthetic fluid inclusions XII. Experimental determinations of the liquidus and isochores for a 40 wt. % H2O-NaCl solution: Geochimica et Cosmochimica Acta, v. 55, p. 1053-1063.
  93. Bodnar, R.J., and Beane, R.E., 1980, Temporal and spatial variations in hydrothermal fluid characteristics during vein filling in pre-ore cover overlying deeply buried porphyry copper-type mineralization at Red Mountain,
  94. Arizona: ECONOMIC GEOLOGY, v. 75, p. 876-893.
  95. Bodnar, R.J., Burnham, C.W., and Sterner, S.M., 1985, Synthetic fluid inclusions in natural quartz. III. Determination of phase equilibrium properties
  96. in the system H2O-NaCl to 1000 degrees C and 1500 bars: Geochimica et Cosmochimica Acta, v. 49, p. 1861-1873.
  97. 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.
  98. Clark, A.H., Archibald, D.A., Lee, A.W., Farra, E., and Hodgson, C.J., 1998, Laser probe 40Ar/39Ar ages of early- and late-stage alteration assemblages, Rosario porphyry copper-molybdenum deposit, Collahuasi district, I region,
  99. Chile.: ECONOMIC GEOLOGY, v. 93, p. 326-337.
  100. Cline, J.S., and Bodnar, R.J., 1994, Direct evolution of brine from a crystallizing silicic melt at Questa, New Mexico, molybdenum deposit: ECONOMIC GEOLOGY, v. 89, p. 1780-1802.
  101. Cline, J.S., and Vanko, D.A., 1995, Magmatically generated saline brines related to molybdenum at Questa, New Mexico, USA: Mineralogical Association of Canada Short Course Series, v. 23, p. 153-174.
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  119. Hedenquist, J.W., Arribas, A., and Reynolds, T.J., 1998, Evolution of an intrusion-centered hydrothermal system: Far Southeast Lepanto porphyry and epithermal Cu-Au deposits, Philippines: ECONOMIC GEOLOGY, v. 93, p. 374-404.
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  126. GEOLOGY, v. 97, p. 1741-1777.
  127. Lee, A.W., 1994, Evolution of the Rosario copper-molybdenum porphyry deposit and associated copper-silver vein system, Collahuasi district, I region, northern Chile: Unpublished M.A. thesis, Kingston, Ontario, Canada, Queens University, 75 p.
  128. Lindsay, D.D., Zentilli, M., and Rojas De La Rivera, J., 1995, Evolution of an active ductile to brittle shear system controlling mineralization at the Chuquicamata porphyry copper deposit, northern Chile: International Geology Reviews, v. 37, p. 945-958.
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  138. Masterman, G.J., Cooke, D.R., Berry, R.F., Clark, A.H., Archibald, D.A., Mathur, R., Walshe, J.L., and Duran, M., 2004, 40Ar/39Ar and Re-Os geochronology of porphyry copper-molybdenum deposits and related copper-silver veins in the Collahuasi district, northern Chile: ECONOMIC GEOLOGY,
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  174. -1995, Epithermal gold deposits: Styles, characteristics and exploration: Society of Economic Geologists Newsletter 23, p. 1, 9-13." name="eprints.referencetext" />
  175. <meta content="Masterman, G.J. and Cooke, D.R. and Berry, R.F. and Walshe, J.L. and Lee, A.W. and Clark, A.H. (2005) Fluid Chemistry, Structural Setting, and Emplacement History of the Rosario Cu-Mo Porphyry and Cu-Ag-Au Epithermal Veins, Collahuasi District, Northern Chile. Economic Geology, 100 (5). pp. 835-862. ISSN 0361-0128" name="eprints.citation" />
  176. <meta content="http://eprints.utas.edu.au/1990/1/Masterman%2C_Cooke_et_al_ECON_GEOL_2005.pdf" name="eprints.document_url" />
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  178. <meta content="Fluid Chemistry, Structural Setting, and Emplacement History of the Rosario
  179. Cu-Mo Porphyry and Cu-Ag-Au Epithermal Veins, Collahuasi District, Northern Chile" name="DC.title" />
  180. <meta content="Masterman, G.J." name="DC.creator" />
  181. <meta content="Cooke, D.R." name="DC.creator" />
  182. <meta content="Berry, R.F." name="DC.creator" />
  183. <meta content="Walshe, J.L." name="DC.creator" />
  184. <meta content="Lee, A.W." name="DC.creator" />
  185. <meta content="Clark, A.H." name="DC.creator" />
  186. <meta content="260100 Geology" name="DC.subject" />
  187. <meta content="The Rosario Cu-Mo-Ag deposit is located in the Collahuasi district of northern Chile. It comprises high-grade
  188. Cu-Ag-(Au) epithermal veins, superimposed on the core of a porphyry Cu-Mo orebody. Rosario has mining reserves
  189. of 1,094 million metric tons (Mt) at 1.03 percent copper. An additional 1,022 Mt at 0.93 percent copper
  190. occurs in the district at the nearby Ujina and Quebrada Blanca porphyry deposits. The Rosario reserve contains
  191. over 95 percent hypogene ore, whereas supergene-sulfide ores dominate at Ujina and Quebrada Blanca.
  192. Mineralized veins are hosted within Lower Permian volcanic and sedimentary rocks, Lower Triassic granodiorite
  193. and late Eocene porphyritic quartz-monzonite. The Rosario fault system, a series of moderate southwest-
  194. dipping faults, has localized high-grade Cu-Ag-(Au) veins. At Cerro La Grande, similar high-grade Cu-
  195. Ag-(Au) veins are hosted in north-northeast-trending, sinistral wrench faults. Normal movement in the Rosario
  196. fault system is interpreted to have been synchronous with sinistral strike-slip deformation at La Grande.
  197. Hydrothermal alteration at Rosario is characterized by a K-feldspar core, focused in the Rosario Porphyry
  198. that grades out to a secondary biotite-albite-magnetite assemblage. Paragenetic relationships indicate that magnetite
  199. was the earliest formed alteration product but has been replaced by biotite-albite. Vein crosscutting relationships
  200. indicate that K-feldspar formed during and after biotite-albite alteration. Chalcopyrite and bornite
  201. were deposited in quartz veins associated with both K-feldspar and biotite-albite assemblages. The early hydrothermal
  202. fluid was a hypersaline brine (40-45 wt % NaCl) that coexisted with vapor between 400 degrees and
  203. >600 degrees C. Weakly mineralized illite-chlorite (intermediate argillic) alteration of the early K and Na silicate assemblages
  204. was caused by moderate temperature (250 degrees-350 degrees C), moderate-salinity brines (10-15 wt % NaCl).
  205. Molybdenite was precipitated in quartz veins that formed between the potassic and intermediate argillic alteration
  206. events. These fluids were 350 degrees to 400 degrees C with salinities between 10 and 15 wt percent NaCl.
  207. Porphyry-style ore and alteration minerals were overprinted by structurally controlled quartz-alunite-pyrite,
  208. pyrophyllite-dickite, and muscovite-quartz (phyllic) alteration assemblages. The quartz-alunite-pyrite alteration
  209. formed at 300 degrees to 400 degrees C from fluids with a salinity of 10 wt percent NaCl. The pyrophyllite-dickite assemblage
  210. formed between 250 degrees and 320 degrees C from dilute (5 wt % NaCl) fluids. An upward-flared zone of muscovite-
  211. quartz-pyrite altered rocks surrounds the fault-controlled domain of advanced argillic alteration. Thick
  212. veins (0.5-2 m wide) of fault-hosted massive pyrite, chalcopyrite, and bornite precipitated brines with a salinity
  213. of 30 wt percent NaCl at temperatures of 250 degrees to 300 degrees C.
  214. Pressure-depth estimates indicate that at least 1 km of rock was eroded at Rosario between formation of the
  215. K-Na silicate and advanced argillic assemblages. This erosion was rapid, occurring over a period of 1.8 m.y. The
  216. Rosario Porphyry intruded immediately after the Incaic tectonic phase, implying that it was emplaced as the
  217. Domeyko Cordillera underwent gravitational collapse, expressed as normal faults in the upper crust. Gravitational
  218. sliding potentially accelerated exhumation and helped to promote telescoping of the high-sulfidation environment
  219. onto the Rosario Porphyry.
  220. The hydrothermal system responsible for porphyry Cu mineralization at Rosario was partially exhumed prior
  221. to the formation of high-sulfidation ore and alteration assemblages. This implies that emplacement of a second
  222. blind intrusion occurred somewhere beneath the Rosario and Cerro La Grande high-sulfidation vein systems
  223. and is supported by the fault geometry and zoning of precious metals and sulfosalts at the district scale." name="DC.description" />
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  337.     <h1 class="ep_tm_pagetitle">Fluid Chemistry, Structural Setting, and Emplacement History of the Rosario Cu-Mo Porphyry and Cu-Ag-Au Epithermal Veins, Collahuasi District, Northern Chile</h1>
  338.     <p style="margin-bottom: 1em" class="not_ep_block"><span class="person_name">Masterman, G.J.</span> and <span class="person_name">Cooke, D.R.</span> and <span class="person_name">Berry, R.F.</span> and <span class="person_name">Walshe, J.L.</span> and <span class="person_name">Lee, A.W.</span> and <span class="person_name">Clark, A.H.</span> (2005) <xhtml:em>Fluid Chemistry, Structural Setting, and Emplacement History of the Rosario Cu-Mo Porphyry and Cu-Ag-Au Epithermal Veins, Collahuasi District, Northern Chile.</xhtml:em> Economic Geology, 100 (5). pp. 835-862. 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/1990/1/Masterman%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/1990/1/Masterman%2C_Cooke_et_al_ECON_GEOL_2005.pdf"><span class="ep_document_citation">PDF</span></a> - Full text restricted - Requires a PDF viewer<br />2467Kb</td><td><form method="get" accept-charset="utf-8" action="http://eprints.utas.edu.au/cgi/request_doc"><input value="2465" 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/10.2113/100.5.835">http://dx.doi.org/10.2113/100.5.835</a></p><div class="not_ep_block"><h2>Abstract</h2><p style="padding-bottom: 16px; text-align: left; margin: 1em auto 0em auto">The Rosario Cu-Mo-Ag deposit is located in the Collahuasi district of northern Chile. It comprises high-grade&#13;
  339. Cu-Ag-(Au) epithermal veins, superimposed on the core of a porphyry Cu-Mo orebody. Rosario has mining reserves&#13;
  340. of 1,094 million metric tons (Mt) at 1.03 percent copper. An additional 1,022 Mt at 0.93 percent copper&#13;
  341. occurs in the district at the nearby Ujina and Quebrada Blanca porphyry deposits. The Rosario reserve contains&#13;
  342. over 95 percent hypogene ore, whereas supergene-sulfide ores dominate at Ujina and Quebrada Blanca.&#13;
  343. Mineralized veins are hosted within Lower Permian volcanic and sedimentary rocks, Lower Triassic granodiorite&#13;
  344. and late Eocene porphyritic quartz-monzonite. The Rosario fault system, a series of moderate southwest-&#13;
  345. dipping faults, has localized high-grade Cu-Ag-(Au) veins. At Cerro La Grande, similar high-grade Cu-&#13;
  346. Ag-(Au) veins are hosted in north-northeast-trending, sinistral wrench faults. Normal movement in the Rosario&#13;
  347. fault system is interpreted to have been synchronous with sinistral strike-slip deformation at La Grande.&#13;
  348. Hydrothermal alteration at Rosario is characterized by a K-feldspar core, focused in the Rosario Porphyry&#13;
  349. that grades out to a secondary biotite-albite-magnetite assemblage. Paragenetic relationships indicate that magnetite&#13;
  350. was the earliest formed alteration product but has been replaced by biotite-albite. Vein crosscutting relationships&#13;
  351. indicate that K-feldspar formed during and after biotite-albite alteration. Chalcopyrite and bornite&#13;
  352. were deposited in quartz veins associated with both K-feldspar and biotite-albite assemblages. The early hydrothermal&#13;
  353. fluid was a hypersaline brine (40-45 wt % NaCl) that coexisted with vapor between 400 degrees and&#13;
  354. &gt;600 degrees C. Weakly mineralized illite-chlorite (intermediate argillic) alteration of the early K and Na silicate assemblages&#13;
  355. was caused by moderate temperature (250 degrees-350 degrees C), moderate-salinity brines (10-15 wt % NaCl).&#13;
  356. Molybdenite was precipitated in quartz veins that formed between the potassic and intermediate argillic alteration&#13;
  357. events. These fluids were 350 degrees to 400 degrees C with salinities between 10 and 15 wt percent NaCl.&#13;
  358. Porphyry-style ore and alteration minerals were overprinted by structurally controlled quartz-alunite-pyrite,&#13;
  359. pyrophyllite-dickite, and muscovite-quartz (phyllic) alteration assemblages. The quartz-alunite-pyrite alteration&#13;
  360. formed at 300 degrees to 400 degrees C from fluids with a salinity of 10 wt percent NaCl. The pyrophyllite-dickite assemblage&#13;
  361. formed between 250 degrees and 320 degrees C from dilute (5 wt % NaCl) fluids. An upward-flared zone of muscovite-&#13;
  362. quartz-pyrite altered rocks surrounds the fault-controlled domain of advanced argillic alteration. Thick&#13;
  363. veins (0.5-2 m wide) of fault-hosted massive pyrite, chalcopyrite, and bornite precipitated brines with a salinity&#13;
  364. of 30 wt percent NaCl at temperatures of 250 degrees to 300 degrees C.&#13;
  365. Pressure-depth estimates indicate that at least 1 km of rock was eroded at Rosario between formation of the&#13;
  366. K-Na silicate and advanced argillic assemblages. This erosion was rapid, occurring over a period of 1.8 m.y. The&#13;
  367. Rosario Porphyry intruded immediately after the Incaic tectonic phase, implying that it was emplaced as the&#13;
  368. Domeyko Cordillera underwent gravitational collapse, expressed as normal faults in the upper crust. Gravitational&#13;
  369. sliding potentially accelerated exhumation and helped to promote telescoping of the high-sulfidation environment&#13;
  370. onto the Rosario Porphyry.&#13;
  371. The hydrothermal system responsible for porphyry Cu mineralization at Rosario was partially exhumed prior&#13;
  372. to the formation of high-sulfidation ore and alteration assemblages. This implies that emplacement of a second&#13;
  373. blind intrusion occurred somewhere beneath the Rosario and Cerro La Grande high-sulfidation vein systems&#13;
  374. and is supported by the fault geometry and zoning of precious metals and sulfosalts at the district scale.</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">fluid inclusions structure telescoping high sulfidation</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 &gt; 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">1990</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 14:57</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=1990;">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&amp;eprintid=1990">item control page</a></p>
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