A Comparison of Fluid Origins and Compositions in Iron Oxide-copper-gold and Porphyry-Cu (Mo-Au) Deposits

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1 A Comparison of Fluid Origins and Compositions in Iron Oxide-copper-gold and Porphyry-Cu (Mo-Au) Deposits Brian Rusk, Poul Emsbo, Roberto Xavier, Louise Corriveau, Nick Oliver and Dexian Zhang B50s

Magmatic-Hydrothermal System Common Alteration styles Low sulphidation epithermal deposit High sulphidation epithermal deposit Argillic alteration Volcanic Rocks Propylitic alteration

2 Magmatic-Hydrothermal System Common Alteration styles Low sulphidation epithermal deposit High sulphidation epithermal deposit Argillic alteration Volcanic Rocks Propylitic alteration Intrusive Breccia Phyllic alteration Breccia Propylitic alteration Porphyry Cu deposit Metasedimentary Basement Barren interior Potassic alteration Limestone ~1 km Skarn & manto deposit Felsic intrusion

3 Potential genetic models leading to observed alteration zonation in iron-oxidecopper-gold deposits Barton et al., 2004, 2014

4 El Salvador Wood Camp, AZ Vapor and brine inclusions are typical of porphyry copper deposits Alumbrera Butte

5 Fluid unmixing in porphyry Cu deposits Heinrich et al., 1999 Bajo de la Alumbrera Low salinity CO2-bearing fluids supply fluids from magma below to hydrothermal system above Rusk et al., 2004; Landtwing, 2010

B50 inclusions are common in many porphyry type deposits

USA El Salvador, Porphyry-Cu-Mo, Chile Butte Mineral

porphyry-mo, CO, USA Mineral Park, Porphyry Cu-Mo, AZ, USA

Porphyry-Cu-Mo, Chile El Teniente, Porphyry Cu-Mo, Chile

6 B50 inclusions are common in many porphyry type deposits Butte, Porphyry-Cu-Mo, MT, USA Henderson, Porphyry-Mo, CO, USA El Salvador, Porphyry-Cu-Mo, Chile Butte Mineral Henderson, Park, AZ CO El Salvador Climax, CO Climax porphyry-mo, CO, USA Mineral Park, Porphyry Cu-Mo, AZ, USA Chuquicamata, prophyry Cu-Mo, Chile Los Pelambres, Porphyry-Cu-Mo, Chile El Teniente, Porphyry Cu-Mo, Chile Yerrington, Porphyry-Cu, NV, USA They are present in MANY significant porphyry-cu-mo deposits

7 IOCG Fluid inclusions (a few key differences from PCDs) Hypersaline (multi-solid ) Halite-saturated (L-V- H) CO2-only (CO2L) Water-NaCl (L-V) The 4 types of fluid inclusions most common to IOCGs

8 Fluid inclusions in IOCG deposits Dominated by halitesaturated brines Vapor-rich inclusions are rare Salty fluids do not appear to be derived from fluid immiscibility

LAICPMS analysis of fluid inclusion Using a laser routed through a petrographic microscope, individual fluid inclusions greater than ~10 microns can be analyzed

9 LAICPMS analysis of fluid inclusion Using a laser routed through a petrographic microscope, individual fluid inclusions greater than ~10 microns can be analyzed for ~10-20 elements simultaneously with detection limits in the range of a few ppm. Time versus intensity Fluid inclusion LA-ICP-MS, Western Washington University

10 Comparison of brines compositions Na/Ca (wt ratio) IOCG fluids IOCG porphyry fluids fluids 1 porphyry Great Bear fluids Cloncurry IOCG Na/K (weight ratio) Porphyry-Cu (Mo-Au) deposits: Bingham, Butte, Los Pelambres, Bata Hijau, and Yerington IOCGs: Sossego, Sequerino, Igarape Bahia, Alvo 118, Pista

11 Rb/Sr (wt ratio) IOCG fluids porphyry fluids K (ppm) IOCG fluids porphyry fluids Na/K (wt ratio) Rb (ppm) IOCG fluids porphyry fluids Sr (ppm) IOCG fluids porphyry fluids Sr (ppm) Ba (ppm) K (ppm) Fluids from IOCG depsosits are enriched in Ca, Ba and Sr relative to magmatic fluids from porphyry deposits. Porphyry fluids have higher K/Rb ratios, Rb/Sr ratios and lower Na/K ratios (More K).

12 Zn (ppm) IOCG fluids 1000 porphyry fluids Pb (ppm) Cu (ppm) IOCG fluids 10 porphyry fluids Fe (ppm) IOCG fluids porphyry fluids Zn (ppm) Zn (ppm) IOCG fluids porphyry fluids Fe (ppm) Mn (ppm) Nearly all analyzed IOCG brines from Carajas contain <200 ppm Cu, 1 to 2 orders of magnitude less Cu than in porphyry Cu brines. Porphyry brines are also enriched in Zn, Mn, and Pb, but contain similar Fe concentrations.

13 Porphyry and IOCG brine compositions compared Average concentration (ppm) Porphyry fluids IOCG fluids Na K Ca Mn Fe Cu Zn Rb Sr Ba Pb 0 12 IOCG brines are strongly enriched in Ca and Sr and Ba and strongly depleted in K, Cu, Zn, and Mn relative to porphyry brines.

magmatic fluids from fluids that have dissolved evaporites Evaporite dissolution Most

14 Halogens in ore fluids Cl/Br ratios differentiate source of salinity. They most clearly differentiate basinal bittern brines (and metamorphic fluids) from magmatic fluids from fluids that have dissolved evaporites Evaporite dissolution Most porphyry-cu brines magmatic Seawater evaporation curve Br/Cl Next slide

15 Halogens from the Carajas District Mixing between magmatic fluids and bittern brines suggested to form the range of deposits in Carajas. Each one with its own individual signature. Xavier et al., 2009, next

Halogens from Ernest Henry, Cloncurry, Australia Evaporite dissolution 0.

16 Halogens from Ernest Henry, Cloncurry, Australia Evaporite dissolution Most porphyry-cu brines magmatic chalcopyrite pyrite Quartz Br/Cl Late carb

17 Potential genetic models leading to observed alteration zonation in iron-oxidecopper-gold deposits Barton et al., 2004, 2014

18 Conclusions Unlike salty fluids in porphyry copper deposits, hypersaine brines in IOCG deposits do not appear to be generated by fluid immmiscibility. IOCG brines are compositionally distinct from porphyry copper brines and contain more Sr, Ba, and Ca, and less metals Whereas halogens in PCDs are compatible with dominantly magmatic fluid sources, halogen data suggests widely variable fluid sources in IOCGs, typically including a significant component of basinal brines.

19 Questions???

22 Hydrothermal fluids in the formation of IOCGs Ligands Sources Fluids Metals Other solutes magmas, wall rocks, preexisting ore deposits e.g. magmatic fluids, groundwater, seawater, bittern brines, metamorphic fluids, mantle fluids, evaporite dissolution Transport Physical transport: faults, fractures, breccias, porous sediments or tuffs, pressure and temperature evolution Chemical transport: fluid composition, ligands, gases, metals, ph, redox state, etc TRAP e.g. Structural traps and fluid chemical changes: cooling, depressurization, fluid neutralization, fluid mixing, fluid boiling, fluid-rock reactions.

23 Butte fluid unmixing diagram

24 Fluid inclusions in IOCG deposits

25 13 minutes. 15 slides. Set up the problem.understanding the origin of fluids that form IOCG deposits. Simple models of PCD formation, well understood, magma derived-not so simple for IOCGs To make IOCG genetic models Compare fluids from porphyry systems where we understand the fluid systems quite well with IOCG systems where we understand less.

26 contents Summarize fluid inclusion characteristics Talk about fluid unmixing in porphs to generate vapor and brine flincs Then talk about abundant brines in IOCGs, but general lack of vapors and evidence for unmixing. So calling into question the validity of magmas as salty fluid sources in IOCGs.

27 Intro set the stage Many models of IOCG formation, but porphyry models are easy.

28 Include some images of the samples from Carajas that we analyzed.

29 What is the origin of these high salinity fluids? 1. Magmatic fluids -Direct exsolution from magmas following watersaturation during ascent or crystallization (700->1000 C) or generated by fluid immiscibility leading to the production of vapors and brines 2. Evaporite dissolution Waters - derived from sea water (+- other sources) waters trapped in sedimentary basins, which acquired high salinity due to dissolution of sedimentary evaporite sequences 3. Bittern brines brines trapped in sedimentary basins that derived their salinity by evaporation of H2O 4. Metamorphic Waters - Fluids of variable salinity and CO 2 -content that have equilibrated with rocks during metamorphism at T>300 C.

30 B50 Fluid compositions Rare double bubbles, but CO2-H2O clathrates are common Most contain 2-10 mol% CO2 Mostly 2-5 wt% NaCl equiv. Homogenize between ~325 and 400 Densities between ~0.5 and 0.7 B50 fluid inclusions from Climax

31 Halogens in earth fluids Log (Br/Cl)m PIXE data Starra Ernest Henry Capitan granite: halite assimilation Bulk crushleach data Seawater Py renees: basinal brines, low grade metamorphism Log (I/Cl)m Earth SW England granites Columbian emeralds: high T ev aporite dissolution Chlorine, Bromine, and Iodine studies are increasingly being applied to the study of fluid inclusions to infer the origin of fluids. Cl/Br ratios differentiate source of salinity. They most clearly differentiate basinal bittern brines (and metamorphic fluids) from magmatic fluids from fluids that have dissolved evaporites

A less-recognized, but common inclusion type: B50s Bubble sizes: 35-65% bubble CO2 clathrates common, double bubbles rare: B50s Clathrate melting: +5 -+9 Ice melting temperatures: -2 to -6 Salinities

32 A less-recognized, but common inclusion type: B50s Bubble sizes: 35-65% bubble CO2 clathrates common, double bubbles rare: B50s Clathrate melting: Ice melting temperatures: -2 to -6 Salinities in the range of ~2-9 wt % NaCl equiv CO2 concentrations of up to ~15 mol% B50 fluid inclusions from Climax porphyry Mo deposit Homogenization temperatures ~ degrees C (Butte, Bingham, Mineral Park, Pelambres, Climax, El Teniente, Chuquicamata, Henderson) (Rusk et al, 2008, Redmond et al., 2004, Klemm et al., 2007)

34 Fluid unmixing Porphyry Cu deposits are dominated by inclusions containing brine and vapor These fluids form from unmixing of a parental fluid of magmatic origin The parental fluid has been identified as a low salinity CO2- bearing fluid in several deposits B50s Redmond et al., 2004, Klemm et al., 2007, Rusk et al., 2008

Fluids, fluid processes, genetic models and footprints Brian Rusk Western Washington

35 Fluid sources and geochemical footprints in IOCG deposits How do IOCG deposits form and how do we recognize them? Fluids, fluid processes, genetic models and footprints Brian Rusk Western Washington University, Bellingham, WA, USA; Consultant: Advanced Geoscience Investigations SEG short course on IOCG deposits, Cape Town, South Africa, February, 2015

How common are these parental fluid inclusions in other

???? Quartz-aplite vein dike from Yerington, NV USTs

quartz veins from Butte Veins formed at high pressures

pressures at near magmatic pressures and temperatures.

36 How common are these parental fluid inclusions in other porphyry Cu (Mo-Au) Brain Rock deposits????? Quartz-aplite vein dike from Yerington, NV USTs from Mineral Park, Arizona USTs from Henderson, CO Deep quartz veins from Butte Veins formed at high pressures and temperatures: Deep veins formed under lithostatic pressures at near magmatic pressures and temperatures. Cu-Fe sulfide poor and quartz-rich with potassic alteration or no obvious alteration

37 Fluid inclusion Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) Quartz Using a laser routed through a petrographic microscope, individual fluid inclusions greater than ~10 microns can be analyzed for ~10-20 elements simultaneously with detection limits in the range of a few ppm.

38 Maybe even a Ti in quartz versus isochore diagram Yeah maybe a PT diagram showing PT conditions at butte or similar. And then something showing the Cu-rich nature of B35 inclusions too?

, 2006) Common presence in brain rocks and vein dikes Dominance in deep sulfide-poor, quartz rich veins with potassic alteration (Redmond et al.

39 Fluid pressure and temperature Even though they homogenize ~350 degrees C, a number of lines of evidence suggest that many B50s are trapped at temperatures closer to degrees C. For example: S-isotopes (Field et al., 2005) Ti in quartz (Rusk et al., 2006) Common presence in brain rocks and vein dikes Dominance in deep sulfide-poor, quartz rich veins with potassic alteration (Redmond et al., 2004, Rusk et al., 2008) Combining quartz trace elements with fluid inclusion analysis to determine pressure, temperature, and composition of hydrothermal fluids: An example from brain rock from Mineral Park, AZ

inclusion B50 fluid inclusion LA-ICP-MS signal of a B50

40 Simultaneous determination of pressure, temperature, and composition Contamination and explosion of shallow fluid inclusion B50 fluid inclusion LA-ICP-MS signal of a B50 fluid inclusion from Mineral Park, AZ Na K Si Zn Ti Cu Sr

41 TH ( o C) am02c LV am02c LVS am39k LV am39k LVS am39l LV am39l LVS Sequeirinho FLUIDS IN IOCG DEPOSITS OF THE CARAJÁS MINERAL PROVINCE, BRAZIL C) oth ( am. 319/133,36 am. 319/107,31 Salinidade (% p.e. NaCl) Sossego IOCG deposit ifs H 2 O-NaCl (LVS) ifs H 2 O-NaCl (LV) ifs H 2 O-NaCl (LV) ifs H 2 O-NaCl (LVS) Salinidade (% p.e. NaCl) Sossego TH (C o ) Torresi (2009); Carvalho (2009) Qtz em veio sulfetado Inclusões Tipo I (L+V) 360 Inclusões Tipo II (L+V+S) Pista Salinidade (% em peso equiv. NaCl)

42 Ti Concentrations Isochores Ti in quartz thermobarometer (Thomas et al., 2010) Isochores for a ~3.5 wt% NaCl equiv, ~6 mol% CO 2 fluid; density=~ g/cm 3 (calculated using data of Bowers and Helgeson, 1984) The intersection of calculated isochores with isopleths of Ti concentrations ppm Ti gives temperatures between 560 and 610 C and pressures between ~1.7 and ~2.2 kbars

43 Introduction Porphyry Cu deposits are dominated by inclusions containing brine and vapor These fluids form from unmixing of a parental fluid of magmatic origin The parental fluid has been identified as a low salinity CO2- bearing fluid in several deposits B50s Redmond et al., 2004, Klemm et al., 2007, Rusk et al., 2008

44 Multi-solid fluid inclusions: L-V-Halite ± multiple solid duaghter minerals T h = C wt% NaCl equiv. ± ferropyrosmalite ((Fe,Mn) 8Si 6O 15(OH,Cl)10 ± sylvite ± Fe chloride ± magnetite ± hematite ± calcite ± kutnahorite (Ca(Mn,Mg,Fe++)(CO3)2) V S2 S3 15 microns S1 Halite Mag Mark et al., 2006

45 Variable fluid salinities and temperatures Fluid inclusion data, multiple sources-see references

46 At least 3 and possibly 4 or 5 separate fluids identified

47 SUMMARY OF FLUID INCLUSION TYPES Pollard, 2001

Fluid bulk composition summary: High salinity (30-60 wt% NaCl equiv) Ca-rich brines trapped at temperatures between 200 and 550 C Multi-solid inclusions

48 Fluid bulk composition summary: High salinity (30-60 wt% NaCl equiv) Ca-rich brines trapped at temperatures between 200 and 550 C Multi-solid inclusions more common in ore deposits than in regional alteration More dilute fluids common- possible mixing/dilution CO2-rich fluids common, but significance unclear

49 Fluid compositions and metal contents

50 SO that brings us to the goal of this presentation to compare fluid characteristics in porphyry and IOCG deposits to help to constrain the ore genesis models of these deposit types.

51 Fluid metal concentrations: PIXE elemental maps Ca-rich brines are common Elevated metal concentrations Si Cl K Ca High Ba concentration suggests S-deficient fluid Mn Fe Cu Zn Ba Starra fluid inclusion: Williams et al., 2001 Econ. Geol.

Fe and Cu concentrations in Cloncurry IOCGs and regional alteration Worldwide porphyry copper deposits Data of Baker, Mustard, Williams, Ryan, Fu and Mark Highest Cu concentrations

52 Fe and Cu concentrations in Cloncurry IOCGs and regional alteration Worldwide porphyry copper deposits Data of Baker, Mustard, Williams, Ryan, Fu and Mark Highest Cu concentrations found in magmatichydrothermal magnetite deposit with NO Cu mineralization Most IOCGs contain between ~50 and 300 ppm Cu Porphyry Cu brines typically 10 to 100 times more Cu than IOCG brines

53 Where is the C in IOCG fluids? Cu-rich brines from the porphyry Cu deposit in El Salvador, Chile Such inclusions are rare in IOCG deposits

Fluid inclusion Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) Quartz Using a laser routed through a petrographic microscope,

54 Fluid inclusion Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) Quartz Using a laser routed through a petrographic microscope, individual fluid inclusions greater than ~10 microns can be analyzed for ~10-20 elements simultaneously with detection limits in the range of a few ppm.

55 Compositions of hydrothermal fluids Fluid inclusion Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) Counts Time (seconds) Na23 K39 Mn55 Fe57 Cu63 Zn66 As75 Rb85 Sr88 Mo95 Ag107 Ba137 Pb208 With a 193 nm eximer laser shot through a petrographic microscope, individual quartz-hosted fluid inclusions greater than ~10 microns can be analyzed for ~10-20 elements simultaneously.

56 Significance to IOCG deposits. Did we analyze the wrong brines in all of the Carajas deposits? How about Ernest Henry, Osborne, SWAN and Eloise? Are ore fluids that form IOCGs less Cu-rich than ore fluids that form porphyry deposits? CO2 (and S)-rich fluids have been implicated in transporting Cu, Au, and As in magmatic porphyry Cu systems, when fluids unmix into vapors and brine. Could CO2-rich fluids that are commonly observed in IOCG deposits transport metals (especially Cu, Au, and As)? Although CO2- rich fluids are observed in the vast majority of IOCGs, as far as I know, no chemical analyses of these fluids exist

57 Maybe a chart showing compositions of porphyry fluids from various deposits

59 ALL OF THE ABOVE FLUID SOURCES HAVE BEEN IMPLICATED IN IOCG MINERALIZATION- EVEN WITHIN A SINGLE DEPOSIT

60 Halogens in Mantoverde IOCG Mixing of magmatic fluids with bittern brines likely at Mantoverde as well Marschik et al., 2011 (SGA)

61 Noble gas isotopes 40Ar/36Ar ratios imply that the source fluids for Ernest Henry are distinctly different than the source fluids for Osborne and Eloise. Ernest Henry has a distinct magmatic component that mixed with metamorphic fluids and basinal brines. Osborne and Eloise formed from basinal brines and show no magmatic component to their noble gas signatures Kendrick et al. 2008, Fisher and Kendrick, 2008

62 Fluid metal and trace element composition summary Fluids in IOCG deposits are Ca-enriched brines and have distinctly different compositions to magma-derived porphyry Cu brines. The Ca-Ba-Sr-(Pb)-rich nature of these fluids likely results from extensive interaction between brines and wall rocks, altering feldspars to albite IOCG Cu concentrations of <100 to ~500 ppm are far less than is typical in porphyry Cu brines, however a few Cu-enriched ( ppm) fluids have been identified

63 Butte, Montana porphyry Cu geology Rusk et al., 2004 (Chemical Geology) Rusk et al.2008 (Economic Geology)

64 Bingham Canyon, Utah Redmond et al., 2004 (Geology)

65 Trapping conditions of B35 and B60 fluid inclusions B50 inclusions trapped a single phase hydrothermal fluid at pressures greater than the unmixing solvus. Bodnar (1995) In many porphyry deposits, B50 fluids are the original magmatically-derived parental source fluid by which volatiles and metals were transported from the magma below to the oredeposit above.

66 Simplified alteration patterns in a porphyry Cu system Modified from Lowell and Guilbert, 1970

67 Pre-Main Stage geology Rusk et al., 2004 (Chemical Geology) Rusk et al.2008 (Economic Geology)

68 Trapping conditions of B35 and B60 fluid inclusions Bodnar (1995)

69 Show the data for halogens in PCDs

predictive mineral discovery*cooperative Research Centre A legacy for mineral exploration science Mineral Systems Q3 Fluid reservoirs

predictive mineral discovery*cooperative Research Centre A legacy for mineral exploration science Mineral Systems Q3 Fluid reservoirs Mineral Systems Q3 Fluid reservoirs 1 Key Parameter Mineral System Exploration is reflected in scale-dependent translation A. Gradient in hydraulic potential B. Permeability C. Solubility sensitivity to