Noble gas and halogen constraints on regionally extensive mid-crustal Na–Ca metasomatism, the Proterozoic Eastern Mount Isa Block, Australia

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Precambrian Research 163 (2008) 131–150

Noble gas and halogen constraints on regionally extensive mid-crustal Na–Ca metasomatism, the Proterozoic Eastern Mount Isa Block, Australia M.A. Kendrick a,∗ , T. Baker b , B. Fu b,1 , D. Phillips a , P.J. Williams b a

Predictive Mineral Discovery Cooperative Research Centre (pmd*CRC) at the School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia b School of Earth Sciences, James Cook University of North Queensland, Townsville, Queensland 4811, Australia Received 5 June 2006; received in revised form 16 January 2007; accepted 13 August 2007

Abstract Fluid inclusions in late-Isan quartz veins associated with regional Na–Ca alteration (albitisation), in the Mary Kathleen Fold Belt and the Cloncurry District of the Eastern Mt Isa Block, have been analysed for naturally occurring and neutron produced isotopes of Ar, Kr and Xe. The noble gases have been extracted using a thermal decrepitation procedure that enables partial deconvolution of the different fluid inclusion types, including variably saline aqueous, liquid carbon-dioxide and mixed aqueous-carbonic varieties. The variably saline (<5–65 wt%) aqueous fluid inclusions dominate and have 40 Ar/36 Ar values of less than 2700 in most of the samples from across the region. These fluid inclusions have extremely variable molar Br/Cl values of 0.3–4 × 10−3 and I/Cl values of 0.2–35 × 10−6, and the fluids are interpreted to represent sedimentary formation waters derived from the upper crust that have dissolved variable quantities of halite (or scapolite) to achieve their ultra-high salinity. Fluid inclusions in a sample from the Snake Creek anticline in the Cloncurry District have the highest 40 Ar/36 Ar value of ∼25,000 demonstrating a deep magmatic or metamorphic fluid origin in this case. A magmatic origin is favoured because this fluid is very similar to a fluid involved in Iron-Oxide-Copper-Gold (IOCG) mineralization at Ernest Henry that was also interpreted to have a magmatic origin, and because the aqueous fluid inclusions have Br/Cl of ∼1–2 × 10−3 and I/Cl of ∼10 × 10−6 that are similar to mantle-derived igneous rocks. Carbon-dioxide fluid inclusions dominate samples from the Knobby Quarry in the Mary Kathleen Fold Belt and have a maximum 40 Ar/36 Ar value of 6000–7000. These fluid inclusions are estimated to have a 36 Ar concentration of 1–4 ppb, that is similar to the range determined for aqueous fluid inclusions in all the other samples. In addition, aqueous and carbonic fluid inclusions in all the samples have similar 129 Xe/36 Ar plus 84 Kr/36 Ar values that are unfractionated, and close to the air—Air Saturated Water (ASW) range. These data are interpreted to indicate an independent and dominantly metamorphic origin for CO2 , and the presence of mixed aqueous-carbonic fluid inclusions are attributed to fluid mixing and/or mingling, rather than fluid unmixing. However, the data do not preclude the presence of a minor magmatic CO2 component in the samples from the Knobby Quarry. Fluid inclusions in most of the samples from the Mary Kathleen Fold Belt have higher Br/Cl and I/Cl values, higher 36 Ar concentrations and lower maximum 40 Ar/36 Ar values than fluid inclusions in samples from the Cloncurry District. This suggests Na–Ca alteration in these different parts of the Eastern Mt Isa Block occurred independently. However, fluid inclusions associated with Na–Ca alteration in the Cloncurry District have a very similar composition to fluid inclusions in IOCG mineralization-stage quartz veins from Ernest Henry. These data are therefore compatible with a genetic relationship between regional Na–Ca alteration and IOCG mineralization in the Cloncurry District. In both cases the ultra-saline hydrothermal fluids had a dominant origin from sedimentary formation water, but are interpreted to contain a magmatic component sourced from the late-Isan Williams-Naraku Batholiths which may have driven fluid convection. © 2007 Elsevier B.V. All rights reserved. Keywords: Fluid inclusions; Regional alteration; Albitisation; IOCG; Metallogenesis; Fluid convection

1. Introduction ∗

Corresponding author. E-mail address: [email protected] (M.A. Kendrick). 1 Present address: Predictive Mineral Discovery Cooperative Research Centre (pmd*CRC) at the School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia. 0301-9268/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.precamres.2007.08.015

The Eastern Fold Belt of the Proterozoic Mount Isa Inlier of northeast Australia preserves a remarkably extensive record of mid-crustal hydrothermal alteration and metasomatism (de Jong and Williams, 1995; Oliver, 1995; Williams, 1998; Xu,

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Fig. 1. Simplified geological map of the Eastern Fold Belt of the Mt Isa Inlier. The Pilgrim Fault separates the Mary Kathleen Fold Belt (MKFB), from the Cloncurry District. The outcrop of regional Na–Ca alteration is somewhat schematic, but is based on similar maps in Mark et al. (2004) and Oliver (1995). Age constraints are after Page and Sun (1998), Gauthier et al. (2001), Rubenach et al. (2001), Oliver et al. (2004), Mark et al. (2006b) and Rubenach et al. (2008).

2000; Oliver et al., 2004; Mark et al., 2004). Multiple phases of regionally pervasive Na–Ca alteration (albitisation) are observed in both the Mary Kathleen Fold Belt and the Cloncurry District and are locally overprinted by potassic alteration associated with Iron-Oxide-Copper-Gold (IOCG) mineralization (Fig. 1; de Jong and Williams, 1995; Oliver, 1995; Adshead et al., 1998; Baker, 1998; Rubenach and Barker, 1998; Williams, 1998; Rubenach and Lewthwaite, 2002; Mark et al., 2004, 2006a; Oliver et al., 2004). Much of the regional alteration, and the majority of the IOCG deposits, formed during the latter half of the ∼1.6–1.5 Ga Isan orogeny, broadly coincidental with intrusion of the WilliamsNaraku Batholiths (e.g. Page and Sun, 1998; Oliver et al., 2004; Mark et al., 2006a). Nonetheless, the origin of regional Na–Ca

alteration remains controversial and is of special interest because it is seen in a number of terranes that host IOCG deposits and has been inferred to be a part of a larger metallogenic system (Williams, 1994; Barton and Johnson, 1996; Hitzmann, 2000; Pollard, 2001; Oliver et al., 2004). In this study, we utilize the noble gases and halogens as fluid tracers to test if fluids associated with regional Na–Ca alteration had similar origins in the Mary Kathleen Fold Belt and the Cloncurry District (Fig. 1). In addition, we test whether the alteration fluids had similar origins to the mineralizing fluids responsible for IOCG mineralization (see Fisher et al., 2005; Kendrick et al., 2006b, 2007). The noble gases and halogens are ideally suited to determining fluid origins in IOCG terranes where the principal uncertainties are the extent of halite dissolution and the

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relative importance of primary magmatic fluids versus sedimentary formation water and/or metamorphic volatiles (Barton and Johnson, 1996; Hitzmann, 2000; Perring et al., 2000; Baker et al., 2001; Pollard, 2001; Mark et al., 2004, 2006a; Oliver et al., 2004). Magmatic fluids are characterized by a limited range in Br/Cl and I/Cl and can have 40 Ar/36 Ar values of tens of thousands, if sourced from the deep crust or mantle (Burnard et al., 1997; Kendrick et al., 2001, 2007; Ballentine et al., 2002). The halogens are strongly fractionated by interaction with halite, which preferentially excludes Br and I, meaning that halite dissolution strongly reduces fluid Br/Cl and I/Cl values (Zherebtsova and Volkova, 1966; Holser, 1979; Fontes and Matray, 1993; Hanor, 1994). Upper crustal sedimentary formation waters typically have 40 Ar/36 Ar values of less than ∼2000 and the modern atmosphere, or Air Saturated Waters (ASW—seawater or meteoric water) have the lowest 40 Ar/36 Ar values of ∼296 (Kendrick et al., 2002a,b; Ozima and Podosek, 2002). Together, the noble gases and halogens can also provide information on some metamorphic processes: prograde fluids formed by devolatilisation of crystalline basement are likely to have high (magmatic-like) 40 Ar/36 Ar values, low 36 Ar concentrations and low salinity (e.g. <20 wt%; Bennett and Barker, 1992; Phillips and Powell, 1993; Kendrick et al., 2006a). Whereas lower 40 Ar/36 Ar values (i.e. <2000) could result from devolatisation of 36 Ar-rich sedimentary (or meta-sedimentary) rocks (Kendrick et al., 2006a, 2007). In addition at low water-rock ratios, the fluids’ salinity, 36 Ar concentration and Br/Cl values could be elevated by retrograde hydration reactions (Bennett and Barker, 1992; Svensen et al., 2001; Kendrick et al., 2006a). Finally, because the halogens are extracted from aqueous fluid inclusions, and the noble gases are extracted from both aqueous and carbonic fluid inclusions (Kendrick et al., 2006b, 2007), these data are complementary to stable isotope studies (C, O, H) that seek to constrain the origin of the major volatile components directly (e.g. Oliver et al., 1993; Mark et al., 2004; Marshall et al., 2006). However, unlike stable isotopes, the noble gases are strongly incompatible in crustal minerals meaning that they preferentially enter the fluid phase and do not undergo isotopic exchange (Ballentine et al., 2002; Ozima and Podosek, 2002). As a result the fluid noble gas concentration is increased during wall rock interaction and helps determine the extent of wall rock interaction and/or phase separation, as well as the origin of the primary fluid (Kendrick et al., 2006a). 2. Geology 2.1. Metamorphism and magmatism Peak metamorphism in the Eastern Fold Belt occurred synchronously with E-W shortening (D2 ) at 1595–1575 Ma (Foster and Rubenach, 2006). Amphibolite grade rocks predominate in the Mary Kathleen Fold Belt (Oliver et al., 1992), but elsewhere peak metamorphic grades increase from greenschist to upperamphibolite facies in a generally southeasterly direction (Foster and Rubenach, 2006). Meta-sedimentary rocks include the 1760–1720 Ma evaporite-rich calc-silicate supracrustal rocks of

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the Corella Formation and equivalents (cover sequence 2), which are associated with intercalated metavolcanic rocks and intrusions, and the younger 1680–1650 Ma siliclastic-rich rocks of the Soldiers Cap Group (cover sequence 3; Blake, 1987; Page and Sun, 1998). The regionally extensive Williams-Naraku Batholiths intruded during two phases of post-peak metamorphic magmatism (Fig. 1; Page and Sun, 1998). Granodiorite-tonalitetrondhjemite suite intrusions were emplaced close to the Cloncurry Fault around ∼1550 Ma, followed by intrusion of the volumetrically most abundant phases of the Williams-Naraku Batholiths between ∼1540 Ma and ∼1490 Ma (Fig. 1; Wyborn et al., 1988; Page and Sun, 1998). These late- to post-D3 granitoids probably formed in an intra-continental/back arc setting, they have extremely variable compositions and have been variably classified as I- or A-type (Wyborn et al., 1988; Page and Sun, 1998; Pollard et al., 1998; Wyborn, 1998; Mark, 2001). Melt generation is considered to have taken place in the plagioclase stability field at a depth of ≤25–30 km and may have been triggered by the introduction of mantle melts in a mafic underplate (Page and Williams, 1988; Wyborn et al., 1988; MacCready et al., 1998; Pollard et al., 1998; Mark, 2001). At the current level of exposure, the more mafic phases, which have a possible mantle-origin, include hornblende-diopside monzonites and quartz diorites (Wyborn, 1998; Mark, 1999). The more dominant felsic phases with 65–77 wt% SiO2 , which include K-rich porphyritic monzodiorite, monzogranite, granodiorite and granite, formed by re-melting of multiply reworked Paleoproterozoic igneous rocks with depleted mantle Sm-Nd model ages of ∼2.2–2.3 Ga (Wyborn et al., 1988; Page and Sun, 1998; Wyborn, 1998; Mark, 2001). 2.2. Post-peak metamorphic Na–Ca alteration Zones of intense Na–Ca alteration have been mapped throughout the Eastern Fold Belt (Fig. 1) and are now known to have formed in several discrete episodes (Rubenach and Barker, 1998; Rubenach and Lewthwaite, 2002; Oliver et al., 2004; Rubenach et al., 2008). The focus of this study, is the late-Isan post-peak metamorphic albitisation that is associated with D3 shear zones that overprint the main metamorphic fabric (de Jong and Williams, 1995; Oliver, 1995). The Na–Ca alteration is most intensely developed in calc-silicate rocks which host veins and breccias rich in albitic-plagioclase, amphibole, plus calcite and commonly contain clinopyroxene, magnetite, quartz, scapolite, biotite, titanite or apatite (Oliver et al., 1993, 2004; Oliver, 1995; Mark et al., 2004; Marshall et al., 2006). Calc-silicate rocks are most abundant in the Mary Kathleen Fold Belt, where approximately 20% of the exposed rocks are affected by intense Na–Ca alteration and giant calcite ‘pods’ 100’s of metres in size have been quarried (Oliver, 1995; Oliver et al., 2004). Metapelite-hosted alteration tends to be more sodic in character with more abundant albite, fewer calcic phases and only rare quartz (de Jong and Williams, 1995; Rubenach and Barker, 1998; Rubenach and Lewthwaite, 2002). Limited U–Pb ages from hydrothermal titanites, formed during the dominant phase of Na–Ca alteration in both the Mary

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Kathleen Fold Belt and the Cloncurry District, and zircons in albitised granites, confirm that much of the alteration occurred after peak-metamorphism at ∼1530–1520 Ma (Oliver et al., 2004; Mark et al., 2006b). However, a single titanite from the Knobby Quarry calcite ‘pod’ (Fig. 1) gave an earlier age of ∼1555 Ma, reflecting either multiple phases of post-peakmetamorphic Na–Ca alteration or that albitisation had an earlier onset in the Mary Kathleen Fold Belt than in the Cloncurry District (Oliver et al., 2004). Due to the channelised nature of fluid flow, earlier phases of pre-Isan and peak-metamorphic albitisation are preserved in isolated pockets of unaltered rock (Oliver, 1995). For example, Na–Ca alteration at the Osborne Mine has a U–Pb titanite age of ∼1595 Ma, that is within error of IOCG mineralization and peak metamorphism at this locality (Gauthier et al., 2001; Rubenach et al., 2001, 2008). Pre-Isan and peak-metamorphic albitisation are also preserved in parts of the Soldiers Cap Group and dominate meta-pelites in the Snake Creek Anticline (Rubenach and Barker, 1998; Rubenach and Lewthwaite, 2002; Rubenach et al., 2008). Nonetheless, the dominant district-wide Na–Ca alteration at ∼1530–1520 Ma overlaps intrusion of the volumetrically most significant phases of the Williams-Naraku Batholiths at 1540– 1490 Ma (Page and Sun, 1998) and the majority of IOCG deposits with ages of 1540–1505 Ma (Mark et al., 2006a). For example, IOCG mineralisation at Ernest Henry, regional Na–Ca alteration, and intrusion of the 15 km distant Mt Margaret granite, all occurred close to ∼1525 Ma (Fig. 1; Page and Sun, 1998; Mark et al., 2006b). A possible relationship between regional Na–Ca alteration and magmatism in the Cloncurry District is further supported by the occurrence of limited granitoid-hosted Na–Ca veins and breccias that are infilled by both crystalline melt and hydrothermal precipitates (Mark and Foster, 2000; Mark et al., 2004). 2.2.1. Petrologic and isotopic constraints Calc-silicate mineral equalibria, calcite–dolomite geothermometry and oxygen isotope geothermometry on quartz, magnetite, albite and amphibole indicate alteration occurred at 400–600 ◦ C (Mark and Foster, 2000; Oliver et al., 2004). The best constraint on pressure comes from quartz-hosted high-density CO2 fluid inclusions that, at 400–600 ◦ C, indicate entrapment at 200–450 MPa (Oliver et al., 2004; Fu et al., 2003, 2004; see also de Jong and Williams, 1995). Previous Br/Cl analyses of two Knobby Quarry quartz samples, obtained from scapolite bearing veins, gave near seawater Br/Cl values (Heinrich et al., 1993), that are consistent with, but do not prove a magmatic fluid origin. More extensive amphibole analyses indicate that, relative to V-SMOW, fluids responsible for vein and breccia-hosted Na–Ca alteration in the Cloncurry District had ␦18 Ofluid of 8.0–12.8‰ and ␦Dfluid in the range −29 to −99‰ (Mark et al., 2004). Relative to V-SMOW and PDB, carbonate veins throughout the Eastern Fold Belt have ␦18 Ocarbonate of 9–18‰ and ␦13 Ccarbonate in the range −0.6 to −7‰ (Oliver et al., 1993; Marshall et al., 2006). These values are intermediate between marine meta-carbonates such as the Corella Formation (␦18 Ocarbonate = 8–20.5‰ and ␦13 Ccarbonate = +2 to −3‰) and calcite in graphitic meta-

sediments of the Soldiers Cap Group (␦18 Ocarbonate = 9–16‰ and ␦13 Ccarbonate = −2 to −13‰; (Oliver et al., 1993; Marshall et al., 2006). Organic carbon preserved as graphite in black shales close to the Dugald River Zn–Pb deposit has an even lower ␦13 C of −22 to −35‰ (Dixon and Davidson, 1996). Together the stable isotope data are interpreted to indicate open system behaviour with an external fluid source (Oliver et al., 1993; Mark et al., 2004; Marshall et al., 2006). Traditionally, a magmatic fluid origin has been preferred, largely because of the possible availability of such fluids from the Williams-Naraku Batholiths (Mark et al., 2004), and because the central parts of the largest veins and calcite pods in the Mary Kathleen Fold Belt, interpreted to be least affected by wall rock interaction, preserve the most igneous-like ␦18 O and ␦13 C values (Oliver et al., 1993; Marshall et al., 2006). However, the stable isotope data are also compatible with sedimentary formation waters or metamorphic fluids derived from outside of the Corella Formation that have equilibrated with igneous rocks or homogenized the isotopic signature of several rock types (Oliver et al., 1993; Mark et al., 2004; Marshall et al., 2006). 2.3. Samples Thirteen quartz vein samples were selected from seven localities at which Na–Ca alteration has been documented previously, and areas with a potassic overprint were avoided (Fig. 1; Oliver et al., 1993, 2004; Oliver, 1995; Xu, 2000; Rubenach and Lewthwaite, 2002; Mark et al., 2004). The mineralogy of the quartz veins selected is summarized in Table 1. Quartz was chosen because fluid inclusions associated with regional Na–Ca alteration have good preservation in quartz and have been characterized previously (de Jong and Williams, 1995; Oliver, 1995; Xu, 2000; Fu et al., 2003, 2004). Furthermore, quartz is well suited to stepped heating experiments used in semi-selective noble gas extraction, meaning that the data can be directly compared with that from IOCG deposits (Fisher et al., 2005; Kendrick et al., 2006b, 2007). However, quartz related to Na–Ca alteration in calc-silicate rocks is commonly formed at the edge of veins, and so the trapped fluids may have been more affected by wall-rock interaction than those trapped in the central calcite-dominated portions of the largest veins and pods (Oliver et al., 1993; Oliver, 1995). In addition, quartz is only rarely associated with the more sodic alteration typical of metapelites (de Jong and Williams, 1995; Rubenach and Barker, 1998; Rubenach and Lewthwaite, 2002). The quartz veins selected from the Knobby Quarry calcite pod in the Mary Kathleen Fold Belt (Fig. 1) include hydrothermal titanite similar to that dated in other samples from this locality (Oliver et al., 2004). However, these samples and other samples selected from this Fold Belt could be related to postpeak metamorphic Na–Ca alteration at either 1520–1530 Ma or ∼1555 Ma (Oliver et al., 2004) because it has not been possible to distinguish these alteration phases petrographically. The quartz veins selected in the Cloncurry District from the Cloncurry Fault and the Marimo Quarry on the Roxmere Station (Fig. 1) were foliation discordant and are correlated with the

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Table 1 Quartz vein samples associated with regional Na–Ca alteration Sample

Host Rock

Vein Mineralogy

Aqueous fluid Inclusions LV

Cloncurry district Snake Creek 02CC47 Soldiers Cap Gp. 02CC50 Soldiers Cap Gp. 02CC52 Soldiers Cap Gp.

LVD

Carbonic fluid Inclusions MS

CO2

LLc

LLc D

Qtz + alb ± bio Qtz ± alb Qtz + alb

50–60% 20–40% 40–60%

10–20% 30–40% 10–20%

20–40% 30–40% 20–30%

0–5% 0–10% 0%

0% 0% 0%

0–1% 0–1% 0%

Qtz + alb + cc ± mag ± act

40–60%

30–40%

10–20%

0%

0%

0%

Qtz

60–70%

10–20%

0–10%

0%

0%

Mary Kathleen Fold Belt Tribulation Quarry area 02CC05 Corella Formation 02CC82 Corella Formation 02CC85 Corella Formation

Qtz + alb + cc + diop Qtz + cc ± alb ± bio Qtz

80–95% 80–90% 70–85%

5–20% 10–20% 15–30%

0% 0% 0%

0% 0% 0–2%

0% 0% 0–2%

0% 0% 0%

Sunrise quarry 02CC62 Corella Formation

Qtz + cc ± alb ± bio

55–95%

0–15%

0%

0–40%

0–10%

0%

Knobby quarry 02CC108 Corella Formation 02CC38 Corella Formation

Qtz + alb + cc + act ± diop ± tit Qtz + alb + cc + act ± tit

5–10% 10–15%

∼10% 5–10%

0–5% 5–10%

80–85% 70–80%

0% 0%

0-2% 0–1%

Lime Creek Quarry 02CC93 Corella Formation 02CC96 Corella Formation

Qtz + cc ± alb ± tour ± act Qtz + tour + act + cc ± alb

60–70% 60–80%

5–10% 10–30%

0–2% 0–20%

5–15% 0–4%

5–15% 0–4%

0–2% 0–1%

Roxmere 02CC113

Corella Formation

Cloncurry Fault 02CC143 Soldiers Cap Gp.

10–20%

Abbreviations: Qtz = quartz, alb = albite, bio = biotite, cc = calcite, mag = magnetite, act = actinolite, diop = diopside, tit = titanite, tour = tourmaline. ± denotes phases that are present in the vein along strike, but were absent from the sample collected. Fluid inclusions: LV, 2 phase liquid–vapour; LVD, liquid–vapour + halite; MS, multi-solid; CO2 , liquid CO2 ± N2 ; LLc , liquid CO2 and liquid water; LLc D, liquid CO2 and liquid water with one or more daughter mineral.

∼1530–1520 Ma ages for albitisation reported for other parts of the Cloncurry District (Oliver et al., 2004). The samples selected from the Snake Creek Anticline have the most ambiguous significance. This locality is overprinted by post-peak metamorphic albitisation that has an age of ∼1530 Ma on the edge of the Saxby Granite (Rubenach et al., 2008), but the area is dominated by relict pre-Isan albitisation (Rubenach and Barker, 1998; Rubenach and Lewthwaite, 2002). In this case, the samples were taken from a quartz boudin with possible pegmatitic affinity (02CC50), and concordant albite-quartz veins (02CC47 and 02CC52) within psammitic layers. Therefore the predominant secondary fluid inclusions in these samples could have been trapped either during peak metamorphism, or they could have a similar timing to the post-peak metamorphic fluid inclusion assemblages preserved at the other localities. 2.3.1. Fluid inclusions The fluid inclusion assemblages in all our samples have been studied in detail. In addition to the four main-types of aqueous and CO2 fluid inclusion recognized previously (de Jong and Williams, 1995; Oliver, 1995; Xu, 2000), we have observed a significant number of mixed aqueous-CO2 fluid inclusions. The main types are defined as: LV, two-phase liquid–vapour; LVD, halite bearing liquid-vapour; MS, multi-solid liquid–vapour;

CO2 , liquid carbon dioxide; LLc , liquid water and liquid carbon dioxide; and LLc D, liquid water, liquid carbon dioxide and one or more daughter minerals (see Fig. 2 and Table 1). Fluid inclusion parageneses are difficult to determine due to the lack of growth zoning and mesothermal nature of quartz veins. However, in many cases LLc or LLc D inclusions can be observed in the same trail as MS, LVD, LV and CO2 fluid inclusions (Fig. 2c). This spatial relationship and the existence of mixed aqueous-carbonic fluid inclusions indicates that the aqueous and carbonic fluid phases are intimately associated with one another. The moderately abundant LLc fluid inclusions in the Lime Creek and Sunrise Quarry samples (Table 1) demonstrate that CO2 was associated with low- as well as high-salinity fluids. However, it has not been possible to determine petrographically, whether the relationship in these samples results from fluid mixing or unmixing (Fig. 2). The fluid inclusion assemblages associated with Na–Ca alteration hosted by different rock-types throughout the region, are variable, but share some common features (Table 1). As Na–Ca alteration is commonly multi-stage, it is suggested that the entire fluid inclusion assemblage, which is dominated by secondary fluid inclusions in most samples, is representative of the variable fluids responsible for Na–Ca metasomatism in different parts of the region (de Jong and Williams, 1995; Oliver, 1995; Fu et al., 2003).

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Fig. 2. Quartz hosted fluid inclusions associated with Na–Ca alteration in the Eastern Fold Belt (Table 1). (a) High purity CO2 fluid inclusions and mixed aqueous-CO2 fluid inclusions. (b) Aqueous fluid inclusions. At the top, the heating schedule shows that the LVD fluid inclusion leaked before its final decrepitation at 408 ◦ C. (c) Examples of different fluid inclusion types trapped on single fluid inclusion trails. Below the CO2 homogenisation temperature CO2 vapour is visible within CO2 liquid—bubbles within bubbles, in LLc , LLc D and CO2 fluid inclusions. Abbreviations as for Table 1.

Daughter minerals in the MS and LLc D fluid inclusions commonly include halite and sylvite plus various iron-rich and unidentified solid phases (Fig. 2a and b). MS fluid inclusions have total homogenization temperatures as high as 550 ◦ C, indicating total salinity of up to ∼65 wt% NaCl eq. LVD fluid inclusions have total homogenization temperatures of 170–300 ◦ C corresponding to salinities of between ∼30 and 40 wt% NaCl eq. Most LV fluid inclusions have homogenization temperatures of 100–200 ◦ C (Fu et al., 2003), but some exhibit metastability and do not re-nucleate a vapour phase after heating. Consequently, we do not distinguish monophase aqueous fluid inclusions from two phase LV inclusions (Fig. 2b). The LV fluid inclusions have first melting temperatures as low as −55 ◦ C and final ice melting temperatures of −50 to ∼0 ◦ C, indicating a Ca-rich composition and wide range of salinities estimated as <5–30 wt% total dissolved solids. Carbonic fluid inclusions have melting points close to the triple point of CO2 at −56.6 ◦ C indicating a high purity. However, CO2 homogenisation into the liquid phase varies between

−20 and +30 ◦ C indicating variable density (0.6–1.0 g cm−3 ). Minor N2 or H2 O (≤3 mol%) is present in some CO2 inclusions (Fu et al., 2003, 2004). The mixed aqueous-carbonic fluid inclusions have variable degrees of CO2 -fill, but always decrepitate before complete homogenization, making it difficult to estimate the salinity of LLc D inclusions. The clathrate melting temperature of LLc fluid inclusions was −10 to +9 ◦ C, indicating salinities of 2–21 wt% NaCl eq. (calculated with FLINCOR; Brown, 1989). The regional alteration samples exhibit similar decrepitation behaviour to that reported for IOCG samples (Kendrick et al., 2006b, 2007). However the exceptional abundance of CO2 fluid inclusions in samples from Knobby Quarry has allowed them to be studied in much greater detail (Table 1). In these and the Lime Creek samples, the mixed aqueous-carbonic fluid inclusions (LLc D and LLc ) decrepitate at the lowest temperatures of 180–250 ◦ C and the pure CO2 fluid inclusions decrepitate at only very slightly higher temperature. Of the aqueous varieties, most LV fluid inclusions decrepitate, in the approximate

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temperature range 300–450 ◦ C, before the higher salinity LVD plus MS fluid inclusions which preferentially decrepitate at temperatures greater than ∼400 ◦ C (e.g. Fig. 2b). However, fluid inclusion decrepitation temperature is also dependent on shape and size (Bodnar et al., 1989; Kendrick et al., 2006b), and some of the smallest fluid inclusions of all the varieties were undecrepitated, or have only partially leaked after heating to 600 ◦ C. 3. Methodology 3.1. Sample preparation and irradiation High purity mm-sized quartz grains (70–120 mg) were cleaned in an ultrasonic bath with distilled water and acetone, packed in Al-foil and irradiated in two batches for 150 MW h in position 5c of the McMaster Nuclear Reactor, Canada (Irradiations designated UM#8 and UM#13). In both cases the neutron fluence was monitored using the Hb3Gr (1072 Ma) and GA1550 (98.8 Ma) flux monitors (Roddick, 1983; Renne et al., 1998; McDougall and Harrison, 1999). J-values were determined from both monitors and the additional ␣ and ␤ parameters were determined from Hb3Gr alone (Roddick, 1983; Kelley et al., 1986). The total neutron fluence (fast and thermal) was calculated as ∼1019 neutrons cm−2 for both irradiations (Appendix). 3.2. Mass spectrometry Sample gas was extracted by stepped heating 69–97 mg of each sample in a tantalum resistance furnace and four smaller sample duplicates (22–47 mg) were analysed by in vacuo crushing in modified nupro® valves. During stepped heating each sample was cyclically heated in increments from an idle temperature of 100 ◦ C up to a maximum of 1560 ◦ C. Individual steps had a duration of 20 min and increased in 50–100 ◦ C increments from 200 ◦ C to 700 ◦ C, but in larger increments at higher temperature (Kendrick et al., 2006b). Extracted gas was gettered by a cold GP50 st707 furnace getter throughout the 20 min heating step and then for a further 20 min using a combination of hot (300 ◦ C) and cold SAES® NP10 st101 and/or SAES® GP50 st707 getters. The purified noble gases were subsequently expanded for isotopic analysis into the MAP-215 noble gas mass spectrometer at the University of Melbourne. Argon isotopes were measured on the Faraday detector and the less abundant Kr and Xe isotopes were measured at a relative gain of ∼400 using the more sensitive electron multiplier detector. 3.3. Gas concentrations and analytical uncertainty Chlorine, Br, I, K, Ca and U are determined from the neutron flux and the measured abundance of nucleogenic (and fissiogenic) noble gas isotopes: 38 ArCl, 80 KrBr , 128 XeI , 39 ArK , 37 ArCa and 134 XeU (Johnson et al., 2000; Kendrick et al., 2006b). The Br/Cl and I/Cl values are proportional to the measured 80 Kr /38 Ar and 128 Xe /38 Ar values (Kendrick et al., 2006b). Br I Cl Cl Analytical uncertainty is highest in low gas volume extraction

Fig. 3. Regional quartz vein K/Cl values determined by in vacuo crushing and stepped heating (≤500 ◦ C) samples from the Cloncurry District and the Mary Kathleen Fold Belt (MKFB; see Table 2).

steps, with minimum values of 0.1% for Ar/Ar ratios, and 2–3% for Kr/Ar and Xe/Ar ratios. Total uncertainty reported at the 1σ level is determined by the relative fluxes of resonant and thermal neutrons which, based on multiple analyses of selected samples and the Shallowater I-Xe standard included in several irradiations, is estimated as 10% for Br/Cl and 15% for I/Cl (Kendrick et al., 2006b). Bulk sample concentrations of K and U are calculated from the total 39 ArK and 134 XeU released during stepped heating analysis, the irradiation parameters, the mass of the sample analysed and the mass-spectrometer sensitivity. The precision is ∼20% for K concentration but is only semi-quantitative for U concentrations as a suitable monitor was unavailable. 4. Noble gas and halogen data 4.1. K-poor quartz Fluid inclusion K/Cl values were determined by in vacuo crushing and from low temperature stepped heating steps (≤500 ◦ C), which preferentially extract fluid inclusions, and are mostly in the range 0.01–0.15 (Fig. 3 and Table 2). These values are slightly lower than have been determined for K-rich IOCG fluids analysed by this technique (Kendrick et al., 2006b, 2007). The two maximum K/Cl values in samples 02CC47 and 02CC62, determined at temperatures of >500 ◦ C, are slightly greater than one, indicating the presence of very minor Kmineral impurities in the quartz matrix or accidentally trapped in the fluid inclusions (Kendrick et al., 2006c). However, the sample K concentrations of 4–73 ppm are sufficiently low that 40 Ar/36 Ar values, age-corrected for post-entrapment in situ production of radiogenic 40 Ar since 1525 Ma, are only ∼1–6% lower than the measured values for most samples and most extraction steps1 . Because the age-correction is so small, the data would not be significantly altered if some of the fluids were 1

The largest corrections were ∼10–40% for samples 02CC52 and 02CC113.

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Table 2 Noble gas, halogen, K and U data summary for regional quartz veins associated with large-scale Na–Ca alteration Sample

Temperature (◦ C)

40 Ar/36 Ar

Cl/36 Ar × 106

40 Ar /Cl × 10−6 E

NaCl eq. wt%

[36 Ar] ppb

[40 ArE ] ppm

F84 Kr

F129 Xe

Range (200–700 ◦ C)b

K/Cl

K

Range

Range

Representativec

Representativec

Representativec

Range

Rangee

Br/Cl × 10−3

I/Cl × 10−6

Range

wt% (FI)

ppm (FI + Matrix)

ppb (FI + Matrix)

12–84 67–280

100–470 34–64

10–25 25–40

0.7–1.8 0.5–0.9

6.8–80 5.8–18

1.3–2.8 0.6–1.9

1.0–1.3 0.57–0.91

6.0–10 2.4–5.4

0.07–0.23 0.08–2.1

1–3.2 >1.8

73

58

U

Agecorrecteda Range

Cloncurry District ∼1530–1520 Ma Na–Ca Alteration Snake Creek 02CC47 200–400 5,870–24,930 >400 2,920–11,740 200–400 >400

1,090–4,960 1,600–4,570

66–130 85–230

27–71 17–23

10–25 25–40

0.5–1.2 0.7–1.1

1.8–12 2.9–6.3

1.1–1.5 0.9–1.1

0.42–0.45 0.38–0.40

4.3–4.9 3.5–3.7

0.07–0.08 0.07–0.26

1.0–1.1 1.5–5.7

43

2

02CC52

200–400 >400

350–460 550–2,010

6–51 100–200

4–10 3–16

10–25 25–40

1.2–3.0 0.8–1.2

0.3–1.7 0.5–4.4

1.1–2.2 1.3–1.9

0.80–1.1 0.57–0.88

1.6–2.2 1.1–2.2

0.06 0.04–0.17

0.8 0.9–3.7

26

3

200–400 >400

290–2,370 530–850

7–94 16–230

3–4 2–4

10–25 25–40

0.7–1.6 0.7–1.1

0.2–0.7 0.3–1.1

1.1–1.9 1.0

0.56–0.82 0.32–0.51

1.4–4.0 0.18–1.2

0.06 0.04–0.17

0.8 0.9–3.7

34

6

200–400 >400

810–2,220 880–2,900

3–57 47–130

28–190 13–20

10–25 25–40

1.1–2.7 1.2–1.9

1.9–33 2.2–5.5

1.7–1.9 0.7–2.1

1.2–1.9 0.53–0.88

2.4–3.7 1.6–2.2

0.05 0.05–0.09

0.7 1.1–2.0

6

1

11–13 8–24

10–25 25–40

2.3–5.7 4.3–6.8

0.8–2.2 1.4–6.6

0.6–1.3 0.6–1.3

1.1–2.3

1.5–3.3 2.8–3.1

5.0–17 5.8–16

0.03 0.04–0.08

0.4 0.9–1.8

5

72

Roxmere 02CC113

Cloncurry Fault 02CC143

Mary Kathleen Fold Belt ∼1555–1520 Ma Na–Ca Alteration Tribulation 02CC05 200–400 540–650 2–27 >400 290–800 8–36 02CC82

200–400 >400

280–630 330–2,720

6–41 20–79

8 2–31

10–25 25–40

1.5–3.8 1.9–3.1

0.5–1.4 0.3–8.5

1.1–2.0 0.5–1.3

0.9–4.5

3.1–3.2 2.5–2.6

3.7–11 6.6–10

0.01–1.4 0.01–0.13

>0.1 0.2–2.9

14

8

02CC85

200–400 >400

360–740 540–1,200

2–26 24–48

17–38 12–23

10–25 25–40

2.4–5.9 3.2–5.1

1.2–6.5 2.1–6.3

1.3–0.9 0.7–1.3

1.0–3.5

3.1–3.2 2.8–3.3

7.3–7.4 4.9–7.7

0–0.01 0.03–0.34

<0.1 0.7–7.5

19

5

200–400 >400

1,260–2,990 2,730–4,220

5–24 16–43

110–180 90–240

10–25 25–40

2.6–6.4 3.6–5.7

7.5–31 15–66

1.5–1.8 1.2–1.6

3.4–4.0 3.1–3.3

19–22 25–31

0.02–0.04 0.04–0.09

0.3–0.5 0.9–2.0

4

7

200–400 >400

1,480–3,920 1,630–7,330

4–14 28–250

170–290 20–64

10–25 25–40

4.4–11 0.6–1.0

12–50 3–18

0.8–1.2 0.7–0.8

1.2–1.4 0.43–0.70

14–20 5.5–7.7

0.14–0.15 0.02–0.27

1.9–2.1 0.4–5.9

31

20

200–400 >400

1,720–6,260 3,720–6,150

1–21 23–64

280–980 57–190

10–25 25–40

2.9–7.3 2.4–3.8

19–170 9.7–52

1.0–1.2 0.8–1.7

1.2–1.3 0.74–1.3

10–13 6.1–11

0.16–0.28 0.13–0.40

2.2–6.2 2.9–8.8

24

2

200–400 >400

840–1,080 490–940

19–24 13–31

23–42 19–30

10–25 25–40

2.6–6.4 5.0–7.9

1.6–7.2 3.2–8.2

1.3–1.7 1.3–1.5

1.2–1.3 0.88–1.3

33–35 29–33

0.07 0.03–0.38

1.0 0.4–5.2

9

5

200–400 >400

520–1,800 580–1,240

2–65 34–99

19–140 8–14

10–25 25–40

0.9–2.4 1.6–2.5

1.3–24 1.4–3.8

1.3–2.3 0.8–1.1

2.0–2.5 2.0–2.4

20–24 24–20

0.05–0.06 0.02–0.11

0.7–0.8 0.4–2.4

12

1

Reference valuesd Meteoric-seawater 295.5 0–17 Mantle fluids ∼44,000 10–30 a Corrected for post-entrapment production of radiogenic 40 Ar.

0 ∼1000

0–30 <8

1.3–2.7 <0.2

0 2–5

2.0–2.1

1.54* 0.9–2.0

0.86* 9.3–40

0.02*

Sunrise 02CC62

Knobby 02CC108

02CC38

Lime Creek 02CC93

02CC96

1.0–3.5

3.6–4.2

b Temperature range considered most representative of fluid inclusion Br/Cl and I/Cl values (Kendrick et al., 2006a). Other parameters based on Ar isotopes only include high temperature data. c Representative Ar concentrations have been calculated from salinity ranges of 10–25 wt% for LV dominated fluid inclusions and 25–40 wt% NaCl eq. for LVD and MS dominated fluid inclusions (see text), but *lower salinities have been used for the Knooby Quarry samples in which Cl-poor CO2 fluid inclusions dominate (Table 1, see text). Although all ratios are molar, Ar concentrations are given in ppb and ppm to enable comparison with Cl and K concentrations, conventionally given by mass. 1 ppb 36 Ar ∼ 1.6 × 103 cm3 g−1 H2 O; 1 ppm 40 Ar ∼ 1.8 cm3 g−1 H2 O. d Reference values in Zherebtsova and Volkova (1966), Burnard et al. (1997), Moriera et al (1998), Johnson et al. (2000) and Ozima and Podosek (2002). Asterisk refers to seawater values. e F129 Xe determined by in vacuo crushing.

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02CC50

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139

Just over half of the samples analysed (three of five samples from the Cloncurry District and five of eight samples from the Mary Kathleen Fold Belt) have maximum 40 Ar/36 Ar values of less than ∼2700 (Table 2). The Knobby Quarry samples, which are dominated by CO2 fluid inclusions, gave the highest 40 Ar/36 Ar values (6000–7000) of any samples from the Mary Kathleen Fold Belt (Table 2 and Fig. 4). The maximum 40 Ar/36 Ar value of ∼25,000 was obtained from the 300 ◦ C extraction step of sample 02CC47 from the Snake Creek Anticline in the Cloncurry District. Lower 40 Ar/36 Ar values were obtained from this sample at >400 ◦ C, suggesting it is the LV or minor CO2 fluid inclusions in this sample that have the highest 40 Ar/36 Ar value (Table 2; Fig. 4). 4.3. Fluid inclusion Ar concentration

Fig. 4. Log–log 40 Ar/36 Ar vs. Cl/36 Ar plot for fluid inclusions in regional quartz samples. The reference 40 ArE /Cl slopes have atmospheric intercepts with 40 Ar/36 Ar = 296.

trapped at ∼1595 Ma, ∼1555 Ma, or anytime after 1525 Ma (full data set in Appendix). 4.2. Fluid inclusion 40 Ar/36 Ar variability The fluid inclusion Cl/36 Ar values vary between 106 and 3 × 108 in a range fairly typical of crustal fluids (Kendrick et al., 2001, 2002b, 2005). When present, the highest salinity LVD and MS fluid inclusions with the highest Cl/36 Ar and lowest 40 ArE /Cl values, are preferentially decrepitated at temperatures of >400 ◦ C (Table 2). Lower Cl/36 Ar and slightly higher 40 ArE /Cl values are obtained from LV and/or CO2 fluid inclusions that are preferentially decrepitated at low temperature (Table 2). The Cl/36 Ar versus 40 Ar/36 Ar diagram permits visualization of the 40 Ar/36 Ar values obtained for different fluid inclusion types (Fig. 4): A positive correlation is obtained if the highest salinity fluid inclusions also have the highest 40 Ar/36 Ar value (e.g. sample 02CC52). The Cl/36 Ar value is not correlated with the 40 Ar/36 Ar value if all the major fluid inclusion types (CO2 , LV, LVD and MS) have similar 40 Ar/36 Ar values, or if the sample is dominated by a single type of fluid inclusion (e.g. samples 02CC108 and 02CC96). Finally, a negative correlation should result, if the CO2 and LV fluid inclusions with the lowest Cl/36 Ar values have the highest 40 Ar/36 Ar values. However, negative correlations are weakly developed in Cl/36 Ar versus 40 Ar/36 Ar space (e.g. sample 02CC47; Fig. 4). This may indicate that, in addition to the fluid inclusion variability, some of the scatter in the 40 Ar/36 Ar versus Cl/36 Ar diagram is due to the presence of a minor atmospheric-component (Turner and Bannon, 1992; Irwin and Reynolds, 1995). An atmospheric-component would move all data points in Fig. 4 variable distances towards air, obscuring negative correlations but reinforcing positive correlations (Kendrick et al., 2007).

The 36 Ar and 40 ArE 2 concentration of the most saline LVD and MS fluid inclusions are calculated from the maximum Cl/36 Ar and minimum 40 ArE /Cl values (determined at temperatures of >400 ◦ C), and representative salinities of 25–40 wt% NaCl eq. (Table 2). The 36 Ar and 40 ArE concentrations of lower salinity LV fluid inclusions are estimated from the maximum Cl/36 Ar and minimum 40 ArE /Cl values determined in the 200–400 ◦ C temperature range, and salinities of 10–25 wt% NaCl eq. (Table 2). The uncertainty in the estimated Ar concentration is determined by the large range of salinity used in the calculation. The LV fluid inclusions are estimated to have similar 36 Ar concentrations as LVD and MS fluid inclusions in any given sample (Table 2). However, the fluid inclusions in samples from the Mary Kathleen Fold Belt, have 36 Ar concentrations of 1–11 ppb, which are consistently higher than those of 0.5–3 ppb, determined for fluid inclusions in Cloncurry District samples (Fig. 5; Table 2). The 36 Ar concentration is unrelated to the 40 Ar/36 Ar value and although the lowest 36 Ar concentrations are calculated for fluid inclusions in samples with the lowest Br/Cl values, these data are not strongly correlated (Fig. 5b). In contrast, the highest 40 ArE concentrations of >50–100 ppm are calculated for fluid inclusions with the highest 40 Ar/36 Ar values (Table 2). 4.3.1. Carbonic fluid inclusions The 36 Ar concentration cannot be directly calculated from the Cl/36 Ar ratio for CO2 fluid inclusions, because the CO2 fluid inclusions do not contain Cl. However, we can place some limits on the 36 Ar concentration of CO2 fluid inclusions by comparing the ‘apparent’ 36 Ar concentrations determined for the assemblage of fluid inclusions that are decrepitated at 200–400 ◦ C in different samples and the abundance of CO2 fluid inclusions in these samples: The Tribulation Quarry samples contain negligible CO2 fluid inclusions (Table 1) and LV fluid inclusions preferentially decrepitated at ≤400 ◦ C in these samples have a maximum 2 40 Ar = excess 40 Ar; 40 Ar E 40 ( ArA = 296 × 36 Ar) or in situ (40 ArR ).

not attributable to an atmospheric origin production from radiogenic decay of 40 K

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Fig. 5. The 36 Ar concentration is plotted as a function of (a) maximum 40 Ar/36 Ar (log scale) determined by stepped heating in the intervals 200–400 ◦ C and >400 ◦ C (b) sample mean Br/Cl determined by stepped heating in the intervals 200–400 ◦ C and 400–700 ◦ C (Table 2). Compositional fields representative of sedimentary formation waters and estimated for metamorphic fluids obtained by devolatilisation of the Corella Formation (see Kendrick et al., 2007) are shown for reference. The magmatic field is based on the highest-40 Ar/36 Ar fluid measured in the Ernest Henry IOCG and in the Cloncurry Na–Ca alteration (see also ovals in Fig 8; Kendrick et al., 2007). 36 Ar concentration of ∼6 ppb (02CC05; Table 2). If LV fluid inclusions in the Knobby Quarry sample 02CC108 also contain 6 ppb 36 Ar, the higher ‘apparent’ 36 Ar concentration of 11 ppb determined for fluid inclusions in this sample (Table 2), could be explained by decrepitation of CO2 fluid inclusions that contain 36 Ar but not Cl. If four times as many CO2 fluid inclusions (∼0.6–1.0 g cm−3 ) are decrepitated as LV fluid inclusions (∼1.0–1.4 g cm−3 ; Table 1), it is implied that the CO2 fluid inclusions contain only ∼1–2 ppb 36 Ar. Alternatively, if the aqueous fluid inclusions in sample 02CC108 had a 36 Ar concentration of only 1 ppb, similar to the ‘apparent’ 36 Ar concentration determined for this sample above 400 ◦ C (Table 2), the CO2 fluid inclusions could contain as much as 3–4 ppb 36 Ar. Although it is difficult to assign an uncertainty to these estimates, the similarity of ‘apparent’ 36 Ar concentrations in samples with 0–80% CO2 fluid inclusions, strongly suggests that the CO2 fluid inclusions are not (strongly) enriched in 36 Ar relative to the aqueous fluid inclusions (compare data from Tables 1 and 2).

radiogenic noble gas elemental composition of mid-crustal fluids (Kendrick et al., 2007). These data do not provide good evidence for phase separation, which leads to highly fractionated F-values of 1 in the residual phase (Kendrick et al., 2001). Fractionated F-values might have been expected if the water-dominated fluid inclusions had exsolved CO2 . Neutron-induced fissiogenic 134 XeU (and 129 XeU ) was preferentially extracted during stepped heating our irradiated samples, indicating that U present at the ppb level is situated in the quartz matrix rather than the fluid inclusions (Table 2). As a result F129 Xe values obtained by stepped heating are not representative of the fluid inclusion values and are not reported (Appendix).

4.4. Krypton, Xe and U The fluid inclusion 129 Xe/36 Ar and 84 Kr/36 Ar values are reported as fractionation values (F84 Kr and F129 Xe) relative to the atmospheric ratios in Table 2 and Fig. 6. The majority of these F-values are in the range expected for mixing a modern air contaminant and fluid inclusion Air Saturated Water (ASW), consistent with the presence of a minor atmospheric component (Fig. 5; Section 4.2; Turner and Bannon, 1992; Irwin and Reynolds, 1995). However, some of the F84 Kr values are less than one, and the data could alternatively represent the non-

Fig. 6. (a) The noble gas fractionation values F129 Xe and F84 Kr determined by in vacuo crushing four samples from the Mary Kathleen Fold Belt, see also F84 Kr in Table 2. FX = (X/36 Ar)sample /(X/36 Ar)air ASW = air saturated water at 0 and 20 ◦ C (Ozima and Podosek, 2002).

M.A. Kendrick et al. / Precambrian Research 163 (2008) 131–150

Fig. 7. Fluid inclusion Br/Cl vs. temperature (200–700 ◦ C). The relative fluid inclusion abundances are given in Table 1, when present the LVD and MS fluid inclusions decrepitate at the highest temperatures. The data are displayed separately for samples from the (a) Mary Kathleen Fold Belt and (b) the Cloncurry District (see Fig. 1). The seawater Br/Cl value is shown for reference, with the range for I-type magmatic fluids shown as a shaded envelope (Zherebtsova and Volkova, 1966; Johnson et al., 2000; Kendrick et al., 2001).

4.5. Non-uniform halogen signatures The Br/Cl values determined for fluid inclusions in each sample are either fairly constant or they decrease as the temperature of the extraction step is increased from 200 to 700 ◦ C (Fig. 7). The decrease in Br/Cl value is strongest for the samples that contain a significant number of LVD and MS fluid inclusions (Fig. 7; Table 1). As these fluid inclusions are preferentially decrepitated at high temperature it is suggested that they have the lowest Br/Cl values. However, the inter-sample variation is greater than the intra-sample variation (Fig. 8) and so it is not possible to assign a range of Br/Cl values as characteristic of any one type of fluid inclusion. The highest Br/Cl values of 2–4 × 10−3 and I/Cl values of up to 35 × 10−6 were obtained from fluid inclusions in samples from the Mary Kathleen Fold Belt (Fig. 5; Table 2). In

141

Fig. 8. Br/Cl vs. I/Cl (linear scales) for fluid inclusions in quartz veins related to (a) regional Na–Ca alteration and (b) the Ernest Henry and Osborne IOCG mineralisation (Fisher et al., 2005; Kendrick et al., 2006b, 2007). The most likely Br/Cl and I/Cl value of magmatic fluids in the Cloncurry District are identified by the ovals in both figures and are based on fluids with the highest 40 Ar/36 Ar values (Kendrick et al., 2007). In general 40 Ar/36 Ar decreases away from this field, the range of values are shown for each sample group where space permits (Table 2). The compositional fields of evaporated seawater, halite and I-type magmatic fluids based on Porphyry Copper ore deposit and mantle diamond fluid inclusions are shown for reference (Zherebtsova and Volkova, 1966; Holser, 1979; B¨ohlke and Irwin, 1992; Johnson et al., 2000; Kendrick et al., 2001).

contrast, fluid inclusions in samples from the Knobby Quarry and the Cloncurry District have much lower Br/Cl values of 0.3–2 × 10−3 and I/Cl values of 0.2–10 × 10−6 (Fig. 8). The Br/Cl values determined for fluid inclusions in the Knobby Quarry samples overlap the range of 1.4–1.7 × 10−3 reported previously for two quartz samples from this location analysed by a different technique (Heinrich et al.,1993). 4.6. Regional variation and comparison with IOCG Fluid inclusions in quartz samples associated with regional Na–Ca alteration in the Mary Kathleen Fold Belt and the Cloncurry District are distinguished from each other by several

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5.1. Dominant, low-40 Ar/36 Ar aqueous fluids

Fig. 9. Fluid inclusion 40 Ar/36 Ar histograms for the regional Na–Ca alteration and IOCG samples (Fisher et al., 2005; Kendrick et al., 2006b, 2007). The values of sedimentary formation water and values estimated for metamorphic volatiles from the Corella Formation and deeply derived magmatic (or metamorphic) fluids are shown for reference (Kendrick et al., 2007).

geochemical parameters: (1) Fluid inclusions generally have higher Br/Cl and I/Cl values in samples from the Mary Kathleen Fold Belt than in samples from the Cloncurry District (Fig. 8). (2) Fluid inclusions have higher 36 Ar concentrations in samples from the Mary Kathleen Fold Belt than in samples from the Cloncurry District (Fig. 5). (3) The maximum fluid inclusion 40 Ar/36 Ar value is lower in samples from the Mary Kathleen Foldbelt than in samples from the Cloncurry District (Fig. 9). Fluids associated with Na–Ca alteration in the Cloncurry District are similar to fluids associated with IOCG mineralization in the Cloncurry District (Figs. 8 and 9; Fisher et al., 2005; Kendrick et al., 2006b, 2007).

5. Discussion The highly variable results obtained from the Mary Kathleen Fold Belt and Cloncurry District samples suggest that multiple fluid sources and processes control the noble gas and halogen composition of fluid inclusions associated with Na–Ca alteration (Fig. 1). In the discussion that follows we group fluid types that may have had similar origins based on their 40 Ar/36 Ar value and XCO2 , rather than their geographic location.

The 40 Ar/36 Ar values of less than ∼2700 that characterize aqueous (LV, LVD, MS) fluid inclusions in the majority of samples (Tables 1 and 2), do not favour a deep magmatic or metamorphic fluid source. Furthermore, the low 40 Ar/36 Ar values are unlikely to be explained by interaction of a deeply derived fluid with upper or mid-crustal rocks because the 36 Ar concentration is not correlated with the 40 Ar/36 Ar value (Fig. 5; cf. Kendrick et al., 2006a). In addition, there is no evidence of Ar-loss during phase separation (Fig. 6) which could lead to the noble gas signature being more easily overprinted (Kendrick et al., 2007). Instead, the moderately high 40 Ar/36 Ar values, are more easily explained if the fluid originated as either sedimentary formation water in the upper crust, or as a metamorphic devolatilisation fluid sourced from 36 Ar-rich meta-sedimentary rocks close to the mid-crustal level of alteration (Kendrick et al., 2007). A predominant origin from sedimentary formation waters rather than as a locally derived metamorphic fluid is favoured by several factors. (1) The variable Br/Cl and I/Cl values of low-40 Ar/36 Ar aqueous fluids indicates different fluid sources in the Mary Kathleen Fold Belt and the Cloncurry District. The variability does not support a single magmatic or rock buffered metamorphic origin for these ligands (cf. Marshall and Oliver, 2006). (2) Published stable isotope data preclude a fluid derived exclusively by devolatilisation of the host rocks (Oliver et al., 1993; Mark et al., 2004; Marshall et al., 2006). (3) Devolatilisation of the calcite-rich Corella Formation would yield a fluid with XCO2 of 0.3–0.75 (Oliver et al., 1992), favouring an even higher than observed abundance of CO2 fluid inclusions in quartz veins hosted by calc-silicate rocks (cf. Table 1). (4) Similarities in the alteration style and fluid inclusion assemblages (Table 1) of diverse protoliths also indicate external fluid buffering (de Jong and Williams, 1995). 5.1.1. Diverse sources of salinity Low-40 Ar/36 Ar aqueous fluid inclusions in samples from the Mary Kathleen Fold Belt have high Br/Cl and I/Cl values, that are similar to those characteristic of bittern brine sedimentary formation waters (Hanor, 1994; Kendrick et al., 2002a,b). Such fluids acquire high I/Cl values by sub-surface fluid interaction with organic-rich sedimentary rocks, whereas their higher than seawater Br/Cl values result from the sub-aerial evaporation of seawater beyond the point of halite saturation (Zherebtsova and Volkova, 1966; Hanor, 1994; Worden, 1996). As a result, the salinity of bittern brines (evaporated seawater) cannot exceed the salinity of halite-saturated seawater (Zherebtsova and Volkova, 1966; Hanor, 1994). The Dead Sea brine is an example of such a fluid with a salinity of ∼31 wt% total dissolved solids (Nissenbaum, 1977). Fluid inclusions in the Mary Kathleen Fold Belt include halite-saturated LVD and MS varieties (Table 1), indicating that if these fluids originated as bittern brines, some additional process has enhanced their salinity. Low-40 Ar/36 Ar aqueous fluids in the Cloncurry District are dominated by lower than seawater Br/Cl values and I/Cl values that are significantly lower than those of fluid inclusions in samples from the Mary Kathleen Foldbelt (Fig. 8). The

M.A. Kendrick et al. / Precambrian Research 163 (2008) 131–150

lowest Br/Cl value of 0.3 × 10−3 , and the lowest I/Cl value of 0.2 × 10−6 , obtained for LVD and MS fluid inclusions in sample 02CC113 (Table 2), are similar to sedimentary formation waters that have dissolved halite (Fig. 8; Holser, 1979; Hermann, 1980; B¨ohlke and Irwin, 1992). Provided halite dissolution occurs in the sub-surface, at greater than atmospheric pressure and temperature, the resultant brine salinity could far exceed that of halite-saturated seawater. Therefore, the total range in Br/Cl and I/Cl values (Fig. 8), and the ultra-high salinity of some low-40 Ar/36 Ar aqueous fluid inclusions, can be explained if bittern brine sedimentary formation waters dissolved variable amounts of halite. The distinct Br/Cl and I/Cl values determined for Na–Ca alteration fluids in the Mary Kathleen Fold Belt compared to the Cloncurry District probably indicates that the original bittern brines in each of these districts had distinct compositions prior to dissolving halite. Therefore, the data suggest broadly similar but independent origins for Na–Ca alteration fluids in the Mary Kathleen Fold Belt, and the Cloncurry District. 5.1.2. Scapolite One difficulty with invoking halite dissolution as an important source of salinity for post-peak (∼1520–1530 Ma) metamorphic alteration fluids in the Eastern Fold Belt is that halite-rich evaporites originally present in the Corella Formation were transformed into scapolite during the ∼1575–1595 Ma metamorphic peak (Foster and Rubenach, 2006). However, if meta-evaporitic scapolite preserves the low Br/Cl and I/Cl values of halite (Pan and Dong, 2003), the dissolution (or devolatilisation) of metamorphic-scapolite could have the same effect as the dissolution of halite. Scapolite dissolution is a viable source for Cldominated ligands in Na–Ca alteration fluids because the alteration overprints the regional metamorphic fabric and replaces scapolite (Oliver, 1995; Foster and Rubenach, 2006; Marshall and Oliver, 2006). However, an alternative explanation is that halite dissolution took place in younger sediments that could have been present above the present erosion level and may have retained halite after peak metamorphism (Kendrick et al., 2007). 5.2. Snake Creek high-40 Ar/36 Ar fluids The maximum measured fluid inclusion 40 Ar/36 Ar value of ∼25,000 in sample 02CC47 from Snake Creek (Table 2) is consistent with the involvement of a deeply derived fluid, of either metamorphic or magmatic origin. Aqueous fluid inclusions with 40 Ar/36 Ar values intermediate between 25,000 and ∼2700 (Tables 1 and 2) probably represent dilute mixtures of this deeply derived fluid and the dominant low-40 Ar/36 Ar sedimentary formation water (Fig. 9). Fluid inclusions in sample 02CC47 could have been trapped any time after peak metamorphism (Section 2.3), suggesting that trapping of metamorphic fluids during an early phase of Na–Ca alteration is possible. However, fluids with high 40 Ar/36 Ar values interpreted to have had a metamorphic basement-origin in the Mt Isa Cu deposit, are distinguished by much higher Br/Cl and I/Cl values than fluid inclusions in sample 02CC47

143

(Kendrick et al., 2006a). In addition, high-40 Ar/36 Ar fluids are not involved in syn-metamorphic IOCG mineralization at Osborne (Fig. 9; Fisher et al., 2005), suggesting that they are not a common feature of peak metamorphism in the district. In contrast, the high-40 Ar/36 Ar fluid inclusions in sample 02CC47 are very similar to fluids that were involved in post-peak-metamorphic IOCG mineralization at Ernest Henry, which were interpreted to have had a magmatic origin (see Figs. 8 and 9; Kendrick et al., 2007). A similar magmatic origin is possible in this case because, the area surrounding the Snake Creek Anticline was overprinted by late-Isan Na–Ca Alteration at ∼1530 Ma, broadly coincidental with intrusion of the nearby Saxby Granite and major phases of the Williams-Naraku Batholiths elsewhere (Fig. 1; Page and Sun, 1998; Mark et al., 2006b; Rubenach et al., 2008). Magmatic fluids sourced from ‘A-type’ granites generated by melting Palaeoproterozoic igneous rocks in the basement would probably have mantle-like Br/Cl and I/Cl values similar to those measured (Kendrick et al., 2007). A small difference between the high-40 Ar/36 Ar fluid inclusions analysed in sample 02CC47 and the Ernest Henry sample is their temperatures of decrepitation (Table 2; Kendrick et al., 2007). The highest 40 Ar/36 Ar value was determined at 300 ◦ C for sample 02CC47 implying a dominant source from low salinity LV (or CO2 ) fluid inclusions (Fig. 4; Section 4.2). In addition, the high-40 Ar/36 Ar fluid inclusions in sample 02CC47 are estimated to have a 36 Ar concentration of <2 ppb, compared to 3–6 ppb for the more saline magmatic fluid inclusions in the Ernest Henry sample (Table 2; Kendrick et al., 2007). If both these fluids had a magmatic origin, the differences in salinity (and 36 Ar concentration) could be explained by the degree to which the pluton they were exsolved from had crystallized (see Cline and Bodnar, 1991). The bulk salinity of magmatic fluids exsolved from plutons in the mid-crust can vary from 2 to 84 wt% NaCl eq. depending on the P-T-XNaCl conditions at which first or second boiling takes place (Cline and Bodnar, 1991). 5.3. CO2 fluid inclusions The noble gas composition of CO2 fluid inclusions is best constrained by the Knobby Quarry samples where they have an abundance of ∼80% (Table 1). These samples have a maximum 40 Ar/36 Ar value of 6000–7000 (Table 2; Fig. 4), which is significantly higher than determined for the dominant aqueous fluid inclusions in most other samples (Section 5.1; Fig. 9). This difference precludes a CO2 origin in these samples by unmixing from the regionally dominant aqueous fluid. The 40 Ar/36 Ar value of 6000–7000 is significantly lower than the MORB mantle value of 44,000 (Burnard et al., 1997; Moriera et al., 1998) and the value of ∼25,000–29,000 determined for ‘magmatic’ fluids associated with late-Isan Na–Ca alteration and IOCG mineralization in the Cloncurry District (Fig. 9; Kendrick et al., 2007). This indicates that a significant proportion of the CO2 had a non-magmatic crustal origin. The most likely source of crustal CO2 is devolatilisation of the calcite-rich calc-silicate rocks that host the most intense alteration (Oliver et al., 1993, 2004; Oliver, 1995; Rubenach and Lewthwaite, 2002; Mark et

144

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al., 2004). CO2 fluid inclusions with a minor N2 component, such as those reported in similar samples related to Na–Ca alteration in the Eastern Fold Belt (Fu et al., 2003, 2004), are common in high-grade metamorphic fluids and commonly have a source from meta-sedimentary units (e.g. Andersen et al., 1993). Nonetheless, it is not possible to completely exclude a minor mantle or magmatic CO2 component, because the 40 Ar/36 Ar value of a CO2 -rich fluid sourced by devolatilisation of the calcsilicate Corella Formation is poorly constrained (Kendrick et al., 2007). Depending on the 36 Ar concentration in the sedimentary protolith, and the extent of Ar-loss during peak metamorphism, the 40 Ar/36 Ar value of a metamorphic fluid sourced by devolatilisation of the calc-silicate Corella Formation could vary from ∼1000 to >7000 (Kendrick et al., 2007). In addition, the Br/Cl and I/Cl values of the aqueous fluid inclusions in the Knobby Quarry samples are similar to those of the mantle (Fig. 8), compatible with but not diagnostic of a magmatic component. 5.3.1. Aqueous-carbonic fluid inclusions CO2 fluid inclusions are much less abundant in samples collected from outside the Knobby Quarry (Table 1), and their 40 Ar/36 Ar compositions must be inferred. The Lime Creek and Cloncurry Fault samples yield 40 Ar/36 Ar values of ∼1000–3000 from both moderately abundant LLc plus CO2 fluid inclusions that are preferentially decrepitated at 200–400 ◦ C, and higher salinity LVD and MS fluid inclusions that are preferentially decrepitated at >400 ◦ C (Table 2; Fig. 4; Sections 2.3 and 4.2). CO2 fluid inclusions are only a minor component of the Snake Creek samples (Table 1) but could be partly responsible for the highest 40 Ar/36 Ar value of ∼25,000 that was measured in a low temperature extraction step from sample 02CC47 (Section 4.2; Table 2). It is difficult to interpret the variable isotopic compositions of these less abundant CO2 fluid inclusions (Table 1). These data could indicate that, like the H2 O-rich fluids, there were multiple sources of CO2 during Na–Ca alteration. However, it is also possible that the isotopic composition of a relatively small CO2 component reflects the isotopic composition of the fluid from which the CO2 most recently mixed, rather than the ultimate source of CO2 . 5.4. CO2 –H2 O mixing versus unmixing Minor fluid unmixing could follow CO2 –H2 O mixing. However, a dominant role for fluid mixing is suggested by the interpretation that sedimentary formation waters are the main source of low-40 Ar/36 Ar aqueous fluids (Section 5.1). Such fluids are not a good source of CO2 , implying that CO2 must have been introduced independently. An independent source for CO2 is further supported by the following arguments: (1) The Arisotope composition of CO2 fluid inclusions, best preserved in the Knobby Quarry samples, is different to that of the dominant aqueous fluids (Section 5.3). (2) Noble gas elemental ratios are unfractionated and the concentration of 36 Ar is similar in CO2 and aqueous fluid inclusions (Section 4.4; Figs. 5 and 6). Alternatively, if phase separation has occurred, this would require that the heavy noble gases are not strongly fractionated

between supercritical H2 O and CO2 under mid-crustal conditions. Finally, (3) unmixing could not have occurred near to the site of entrapment because the high salinity aqueous fluid inclusions homogenize by halite dissolution (Fu et al., 2003, 2004). Nonetheless, unmixing could have occurred distally. 6. Summary The combination of noble gas plus halogen data and the existing stable isotope constraints have lead us to several important interpretations that differ to those based solely on stable isotope data (cf. Oliver et al., 1993; Mark et al., 2004; Marshall et al., 2006). Stable isotope data have previously been used to suggest a regionally homogenous externally derived fluid (Oliver et al., 1993; Mark et al., 2004; Marshall et al., 2006). Our data are compatible with the interpretation of an external fluid source, but indicate a high degree of fluid heterogeneity and demonstrate that alteration fluids in the Mary Kathleen Fold Belt had broadly similar, but independent origins to alteration fluids in the Cloncurry District (Fig. 10). The greater variability displayed by fluid inclusion noble gas and halogen data relative to stable isotope mineral data may be partly attributed to preservation of multiple pulses of fluid flow in fluid inclusion trails that are time integrated (averaged) in the isotopic composition of minerals. However, it is also notable that the fluid inclusion noble gas and halogen compositions described above, vary by orders of magnitude between bittern brine/halite dissolution sedimentary formation waters, metamorphic and magmatic fluids, whereas the stable isotope composition of all these fluid types can overlap (e.g. Ohmoto and Goldhaber, 1997; Taylor, 1997). Therefore the data presented here, together with the stable isotope data, demonstrate that the dominant fluid origin for quartz hosted aqueous fluid inclusions associated with Na–Ca alteration throughout the Eastern Fold Belt was sedimentary formation waters, with halite/scapolite dissolution an important source of salinity. Magmatic fluids were probably involved in late-Isan Na–Ca alteration in the Cloncurry District and it is suggested that these fluids had a very similar range of origins as fluids involved in IOCG mineralization at Ernest Henry (Fig. 1; Kendrick et al., 2007). These data are compatible with district scale convection of sedimentary formation waters driven by heat from the late-Isan Williams-Naraku Batholiths which contributed minor magmatic fluids (Fig. 10). Minor magmatic fluids, including CO2, may also have been present in the Mary Kathleen Fold Belt. However, the 40 Ar/36 Ar composition of CO2 fluid inclusions in the Knobby Quarry samples preclude a pure mantle or magmatic source and late-Isan ‘A-type’ granites do not outcrop in this area (Fig. 1). Instead, metamorphic devolatilisation of the host Corella Formation was probably one of the most important sources of CO2 . We note that the Corella Formation (␦13 C of −1.5 to +2‰) could also have been the main source of C in calcite veins (␦13 C of −0.6 to −7‰), if organic C with a much lower ␦13 C (i.e. −35‰) was dissolved in the regionally dominant low-40 Ar/36 Ar sedimentary formation water (Oliver et al., 1993; Marshall et al., 2006). The highest I/Cl values are significantly above the Seawater Evapora-

M.A. Kendrick et al. / Precambrian Research 163 (2008) 131–150

145

Fig. 10. Schematic diagram based on the Mt Isa seismic tansect (MacCready et al., 1998) and showing the independent late-Isan Na–Ca alteration systems in the Mary Kathleen Fold Belt and the Cloncurry Districts of the Eastern Mt Isa Block. References include (Burnard et al., 1997; Page and Sun, 1998; Mark, 2001; Kendrick et al., 2002a, 2002b). Abbreviations: MKFB, Mary Kathleen Foldbelt; KLB, Kalkadoon-Leichardt Belt; ASW, Air Saturated Water (seawater or meteoric); MORB, Mid-Ocean Ridge Basalt.

tion Trajectory (Fig. 8) indicating that the sedimentary formation waters responsible for Na–Ca alteration had previously interacted with I-rich organic-rich sedimentary rocks (Section 5.1.1; Worden, 1996). A local origin for CO2, and carbonate, is compatible with the most intense Na–Ca alteration and the largest calcite pods being found in the calcite-rich Corella Formation (Oliver et al., 1993; Oliver, 1995; Mark et al., 2004). Acknowledgements This research was funded by the Predictive Mineral Discovery Cooperative Research Centre (pmd*CRC) fluid history (H6) project in collaboration with the fluids and Mt Isa projects (I7 and F3), and is published with permission. Stanislav Szczepanski is thanked for technical assistance in the noble gas laboratory and Nick Oliver is thanked for assistance with sample collection (BF). Geordie Mark is thanked for access to the fluid inclusion stage at Monash University (MK). Although any faults remain our own, MK has benefited from discussions with Mike Rubenach, Damien Foster and Geordie Mark. The manuscripts clarity was further improved by constructive reviews from Ray Burgess and Andrew Tompkins.

Appendix A A.1. Irradiation parameters Parameter

Date J (mean) α (mean) B (mean) Thermal neutron flux (øt ) Fast neutron flux (øt ) Resonance correction (R) I Resonance correction (R) Br Interference corrections K-salt 40 Ar/39 Ar K-salt 38 Ar/39 Ar Ca-salt 39 Ar/37 Ar Ca-salt 36 Ar/37 Ar Samples irradiated Cloncurry MKFB

Irradiation UM#8

UM#13

7th November 2004 0.0185 ± 0.0002 0.55 ± 0.01 4.8 ± 0.3 9.7 × 1018 ± 0.6 × 1018 3.51 × 1018 ± 0.04 × 1018 1.60

20th January 2006 0.0161 ± 0.0002 0.47 ± 0.02 5.14 ± 0.07 8.8 × 1018 ± 0.2 × 1018 3.06 × 1018 ± 0.04 × 1018 1.20

1.25

1.05

0.030 ± 0.002 0.0124 ± 0.0001 0.00069 ± 0.00001 0.00032 ± 0.00001

0.030 ± 0.002 0.0124 ± 0.0001 0.00069 ± 0.00001 0.00032 ± 0.00001

O2CC47, 02CC113 02CC62, 02CC108, 02CC82, 02CC05, 02CC85

02CC52, 02CC50, 02CC143 02CC93, 02CC96, 02CC38

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M.A. Kendrick et al. / Precambrian Research 163 (2008) 131–150

A.2. Noble gas and halogen stepped heating data

Cloncurry District 40

Ar mols (10−15 )

Snake Creek 02CC47, 75 mg 200 438 ± 1 300 15136 ± 13 350 5368 ± 3 400 3817 ± 2 500 5365 ± 4 550 2296 ± 1 600 357.5 ± 0.5 700 375.4 ± 0.3 1100 1410 ± 2 1400 12712 ± 12 1600 3005 ± 3 Total

50280 ± 19

Snake Creek 02CC50, 83 mg 200 498.4 ± 0.4 300 8315 ± 6 400 5032 ± 4 500 2389 ± 1 600 1511 ± 1 700 225.4 ± 0.4 1100 483 ± 1 1400 8798 ± 7 1540 3440 ± 2 Total

30692 ± 10

Snake Creek 02CC52, 89 mg 200 70.7 ± 0.1 300 305.6 ± 0.3 400 1445 ± 1 500 1442 ± 1 600 142.6 ± 0.2 700 23.08 ± 0.02 1100 60.1 ± 0.1 1400 1818 ± 2 1540 375.4 ± 0.2 Total

5683 ± 3

Roxmere 02CC113, 71 mg 200 43.0 ± 0.5 300 621.1 ± 0.5 400 825 ± 1 500 740.4 ± 0.6 600 302.1 ± 0.1 700 37.85 ± 0.01 1100 210.8 ± 0.3 1400 2521 ± 3 1600 367.8 ± 0.5 Total

5668 ± 3

40 Arcorr (10−15 )

434 15067 5325 3776 5255 2215 299 253 560 11878 2896

9074 ± 4

± ± ± ± ± ± ± ± ± ± ±

2 44 13 9 14 5 2 2 8 39 9

47960 ± 64 498.4 8172 4839 2279 1430 225.4 393 8134 3197

± ± ± ± ± ± ± ± ±

0.4 22 14 6 4 0.4 2 26 9

29167 ± 39 70.7 280.2 1292 1398 101.7 15.5 40.9 1251 257

± ± ± ± ± ± ± ± ±

0.1 1.0 5 4 0.8 0.2 0.4 9 2

4707 ± 11 43.0 564 725 631 245.0 37.85 159 1934 290

± ± ± ± ± ± ± ± ±

0.5 2 3 3 0.6 0.01 1 9 2

4629 ± 11

Cloncurry Fault 02CC143, 80 mg 200 274.0 ± 0.4 274.0 300 2401 ± 3 2383 400 2501 ± 2 2461 500 1442 ± 1 1398 600 419.6 ± 0.6 391 700 132.9 ± 0.2 132.9 1100 949 ± 1 903 1400 313.2 ± 0.4 300 1540 640.9 ± 0.8 615 Total

mols

± ± ± ± ± ± ± ± ±

0.4 8 7 4 2 0.2 3 1 2

8857 ± 12

Tribulation Quarry 02CC05, 75 mg 200 61 ± 1 45 300 849.7 ± 0.6 835 350 981.2 ± 0.8 966 400 686.1 ± 0.4 680

± ± ± ±

1 2 3 2

36

Ar mols (10−15 ) 0.07 0.60 0.40 0.42 0.55 0.21 0.030 0.087 0.16 1.01 0.33

± ± ± ± ± ± ± ± ± ± ±

0.01 0.02 0.01 0.01 0.01 0.02 0.004 0.005 0.04 0.01 0.01

3.87 ± 0.05 0.46 1.65 1.33 0.69 0.32 0.08 0.25 1.85 0.73

± ± ± ± ± ± ± ± ±

0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01

7.35 ± 0.03 0.201 0.65 2.80 0.696 0.157 0.014 0.075 1.78 0.312

± ± ± ± ± ± ± ± ±

0.005 0.01 0.02 0.004 0.003 0.009 0.002 0.02 0.004

6.69 ± 0.03 0.15 1.08 1.31 0.87 0.32 0.49 0.30 2.13 0.34

± ± ± ± ± ± ± ± ±

0.03 0.01 0.01 0.01 0.01 0.06 0.02 0.02 0.01

7.0 ± 0.1 0.34 1.07 1.30 0.696 0.444 0.05 0.52 0.16 0.40

± ± ± ± ± ± ± ± ±

0.01 0.01 0.01 0.004 0.003 0.03 0.01 0.02 0.01

4.98 ± 0.04 0.45 1.55 1.60 1.04

± ± ± ±

0.01 0.02 0.02 0.01

84

Kr mols (10−18 ) 4.1 22.6 10.1 9.8 12.7 3.7 1.1 1.1 3.9 22 9

± ± ± ± ± ± ± ± ± ± ±

0.2 0.9 0.5 0.5 0.5 0.2 0.2 0.1 0.2 1 1

100 ± 2 13.9 42.6 29.7 12.7 7.6 1.7 3.7 36 10.4

± ± ± ± ± ± ± ± ±

0.2 0.7 0.5 0.2 0.3 0.0 0.1 1 0.4

158 ± 2 8.7 16.7 59.2 23.6 4.2 0.52 2.31 37.5 5.4

± ± ± ± ± ± ± ± ±

0.1 0.3 0.9 0.3 0.1 0.04 0.04 0.7 0.1

± ± ± ± ± ± ± ± ±

0.2 2 1 0.7 0.3 0.1 0.2 1 0.2

143 ± 3 12.7 36.6 43.3 23.6 6.3 2.0 14.6 2.8 9.2

± ± ± ± ± ± ± ± ±

0.2 0.7 0.7 0.3 0.1 0.1 0.3 0.1 0.2

151 ± 1 5.5 46 39 27

± ± ± ±

0.3 2 2 1

Cl mols (10−9 )

± ± ± ± ± ±

0.06 0.3 0.09 0.04 0.06 0.07

0.9 32 27 36 80 34

± ± ± ± ± ±

0.1 2 2 2 5 2

0.57 0.22 0.8 0.58

± ± ± ±

0.02 0.02 0.1 0.01

5.8 24 285 65

± ± ± ±

0.4 2 18 4

22.5 ± 0.3 5.2 11.9 4.7 0.92 0.63 0.19 0.41 1.54 0.63

± ± ± ± ± ± ± ± ±

0.2 0.4 0.2 0.06 0.02 0.01 0.02 0.05 0.04

4.6 5.7 4.4 1.8 0.36 0.11 0.26 2.1 0.45

± ± ± ± ± ± ± ± ±

± ± ± ± ± ± ± ± ±

0.2 0.2 0.2 0.1 0.02 0.02 0.02 0.1 0.02

0.1 0.5 0.2 0.05 0.02 0.03 0.09 0.05 0.02

35 ± 1 6.5 7.7 3.9 1.8 0.56 0.23 0.73 0.15 0.43

± ± ± ± ± ± ± ± ±

0.2 0.3 0.1 0.1 0.03 0.01 0.03 0.01 0.02

22.0 ± 0.4 2.2 15.6 5.7 3.0

± ± ± ±

± ± ± ±

2 3 2 1

20.9 ± 0.4 432 ± 8 144 ± 3 1032 ± 10

19.8 ± 0.4 2.4 19.2 8.3 1.85 0.63 0.15 0.40 1.65 0.91

595 ± 20

109 170 96 60

0.2 0.5 0.2 0.1

1.18 25.8 144 75 25.7 2.7 7.7 306 54

± ± ± ± ± ± ± ± ±

0.02 0.5 3 1 0.5 0.1 0.1 6 1

642 ± 7 1.1 67 123 141 68 8 43 489 54

± ± ± ± ± ± ± ± ±

0.1 4 8 9 4 1 3 32 3

994 ± 35 0.9 33.3 74 75 20.8 6.0 47.2 16.7 26.7

± ± ± ± ± ± ± ± ±

0.0 0.6 1 1 0.4 0.1 0.9 0.3 0.5

301 ± 2 0.7 35 41 28

± ± ± ±

Br/Cl (10−3 )

K mols (10−9 )

1.73 11.2 3.54 1.85 1.28 0.70

26 ± 1

158 ± 1 5.8 38 29 17.3 6.1 1.2 4.9 35 4.9

129 Xe mols (10−18 )

0.0 2 3 2

0.2 4.1 2.62 2.46 6.6 4.8 4.8 7.3 50.9 49.9 6.5

± ± ± ± ± ± ± ± ± ± ±

0.1 0.1 0.03 0.05 0.1 0.1 0.3 0.1 0.3 0.1 0.1

1.3 1.3 1.1 1.0 0.9 0.80 3.5 0.58 0.72 0.73 0.73

± ± ± ± ± ± ± ± ± ± ±

0.1 0.1 0.1 0.1 0.1 0.08 0.1 0.06 0.08 0.08 0.08

I/Cl (10−6 )

10 7.9 6.2 6.0 5.4 5.9 0.57 5.0 6.6 5.2 5.7

± ± ± ± ± ± ± ± ± ± ±

1 0.8 0.6 0.6 0.6 0.6 0.06 0.5 0.7 0.5 0.6

138.8 ± 0.3

8.6 11.5 6.6 4.9

± ± ± ±

0.1 0.2 0.1 0.1

5.4 ± 0.1 39.7 ± 0.5 14.6 ± 0.2

0.45 0.42 0.40 0.38

± ± ± ±

0.05 0.04 0.04 0.04

0.37 ± 0.04 0.33 ± 0.03 0.23 ± 0.02

5 4.3 3.5 3.7

± ± ± ±

3.5 ± 0.4 3.2 ± 0.3 1.8 ± 0.2

± ± ± ± ± ± ± ±

0.02 0.1 0.04 0.07 0.02 0.02 0.5 0.1

1.1 0.93 0.80 0.88 0.57 0.65 0.69 0.61 0.50

± ± ± ± ± ± ± ± ±

0.1 0.09 0.08 0.09 0.06 0.07 0.07 0.06 0.05

2.2 1.3 1.6 2.2 1.1

± ± ± ± ±

7.2 255 272 155

± ± ± ±

0.4 19 15 16

0.4 0.1 0.2 0.2 0.1

2.6 ± 0.3 1.6 ± 0.2 2.6 ± 0.3

± ± ± ±

0.1 0.1 0.1 0.02

± ± ± ±

0.05 0.05 0.04 0.03

2.78 ± 0.05 0.79 ± 0.03 1.55 ± 0.02

0.70 0.56 0.51 0.44

± ± ± ±

0.07 0.06 0.05 0.05

0.45 ± 0.05 0.42 ± 0.05 0.41 ± 0.04

0.82 1.4 1.4 1.2 1.1 0.32 1.1 1.3 1.4

± ± ± ± ± ± ± ± ±

0.09 0.2 0.1 0.1 0.1 0.03 0.1 0.1 0.1

0.1 0.1 0.03 0.03

± ± ± ±

5 15 29 7

4.0 ± 0.8 24 ± 97 29 ± 11 0.18 542 1159 103

± ± ± ±

0.02 40 81 61

1858 ± 147 1.9 1.8 1.2 0.88 0.67 0.53 0.86 0.57 1.0

± ± ± ± ± ± ± ± ±

0.2 0.2 0.1 0.09 0.07 0.05 0.09 0.06 0.1

3.7 2.7 2.4 2.2 2.0 1.6 1.9 1.8 3.9

± ± ± ± ± ± ± ± ±

0.4 0.3 0.3 0.2 0.2 0.2 0.2 0.2 0.4

13.0 ± 0.1 ± ± ± ±

10 271 614 110

1004 ± 34

62.2 ± 0.3

1.0 0.9 0.92 0.37

24 103 18 32 23 11 0.6 11 93 362 665

690 ± 29

3.1 ± 0.1 35.1 ± 0.1 4.7 ± 0.1

1.13 2.41 2.65 1.69

± ± ± ± ± ± ± ± ± ± ±

1 0.5 0.4 0.4

58 ± 1

3.4 6.0 6.5 3.41

121 1469 205 58 233 84 2.4 11 1329 5192 9486

18189 ± 772

91 ± 1

1.52 9.1 2.65 2.45 0.45 1.15 33.9 7.1

U mols (10−15 )

25 113 39 85

± ± ± ±

4 7 2 5

262 ± 10 1.5 3.3 3.1 2.8

± ± ± ±

0.2 0.4 0.3 0.3

5 12 14 17

± ± ± ±

1 1 1 2

25 117 166 83

± ± ± ±

32 48 25 12

M.A. Kendrick et al. / Precambrian Research 163 (2008) 131–150

147

Cloncurry District 40

Ar mols (10−15 )

450 317.4 ± 0.5 500 169.351 ± 0.001 550 245.0 ± 0.2 600 40.86 ± 0.04 700 45.85 ± 0.01 1100 57.1 ± 0.5 1300 2080 ± 3 1400 280.5 ± 0.3 1600 604 ± 2 Total

6418 ± 3

40

Arcorr mols (10−15 ) 317.4 168.3 239.1 40.86 45.85 56.0 2011 270.6 586

9353 ± 3

13475 ± 7

± ± ± ± ± ± ± ± ±

± ± ± ± ± ± ± ± ±

6653 ± 4

0.0 0.3 2 0.5 1 1 6 18 2

12893 ± 19

Mary Kathleen Fold Belt Lime Creek 02CC93, 97 mg 300 1886 ± 2 1849 ± 400 1301 ± 1 1256 ± 500 589.8 ± 0.3 571 ± 600 394.6 ± 0.1 370 ± 700 197.0 ± 0.4 168 ± 1100 151.4 ± 0.2 149.6 ± 1400 2133 ± 3 2024 ± Total

0.4 0.1 3 3 3 1 2 6 8

8974 ± 11

Tribulation Quarry 02CC85, 73 mg 200 474.59 ± 0.01 474.6 300 1237.94 ± 0.01 1239.4 400 1413.4 ± 0.3 1409 500 844.8 ± 0.5 844.8 600 793.6 ± 0.2 774 700 682.5 ± 0.1 673 1100 1093 ± 3 871 1400 4458 ± 7 4255 1600 2478.2 ± 0.1 2352 Total

0.5 0.1 0.7 0.04 0.01 0.5 7 0.9 3

6261 ± 9

Tribulation Quarry 02CC82, 64 mg 200 190.0 ± 0.0 200.5 300 637.5 ± 0.1 637.5 400 858 ± 1 830 500 800 ± 1 688 600 890 ± 1 880 700 347.06 ± 0.01 320 1100 486.8 ± 0.4 465 1400 3128 ± 1 2979 1600 2016 ± 3 1975 Total

± ± ± ± ± ± ± ± ±

7 4 1 1 1 0.5 8

6387 ± 11

Lime Creek 02CC96, 91 mg 200 191.3 ± 0.3 191.3 ± 0.3 300 1563 ± 2 1542 ± 5 400 1654 ± 1 1595 ± 5 500 641.9 ± 0.5 596 ± 2 600 144.3 ± 0.2 130.4 ± 0.7 700 31.08 ± 0.03 30.6 ± 0.1 1100 49.4 ± 0.1 45.9 ± 0.2 1400 1982 ± 2 1743 ± 7 1540 726.9 ± 0.8 644 ± 3 Total

6983 ± 3

6518 ± 11

Sunrise Quarry 02CC62, 69 mg 200 288.3 ± 0.4 288.3 300 3274 ± 3 3258 400 2504 ± 3 2496 500 1679 ± 2 1669 600 770 ± 1 762 700 176.7 ± 0.1 176.7 1100 798 ± 1 793 1400 4736 ± 5 4670

± ± ± ± ± ± ± ±

0.4 11 9 5 3 0.1 3 16

36

Ar mols (10−15 ) 0.40 0.242 0.41 0.06 0.16 0.13 2.97 0.405 0.78

± ± ± ± ± ± ± ± ±

0.06 0.005 0.01 0.01 0.02 0.01 0.02 0.002 0.02

10.2 ± 0.1 0.70 1.07 1.3 2.1 0.9 0.8 0.39 3.0 0.7

± ± ± ± ± ± ± ± ±

0.02 0.01 0.1 0.1 0.2 0.1 0.01 0.1 0.1

11.0 ± 0.3 1.3 1.67 2.02 1.05 1.00 0.86 1.6 4.11 2.0

± ± ± ± ± ± ± ± ±

0.1 0.03 0.02 0.04 0.03 0.04 0.1 0.03 0.1

15.6 ± 0.2

1.72 1.51 0.735 0.471 0.343 0.160 2.32

± ± ± ± ± ± ±

0.02 0.02 0.004 0.006 0.003 0.005 0.01

7.25 ± 0.03 0.37 0.86 1.03 0.48 0.16 0.041 0.08 1.48 0.54

± ± ± ± ± ± ± ± ±

0.02 0.02 0.01 0.01 0.01 0.002 0.01 0.02 0.02

5.05 ± 0.05 0.23 1.21 0.83 0.429 0.25 0.04 0.20 1.13

± ± ± ± ± ± ± ±

0.01 0.02 0.01 0.005 0.01 0.01 0.02 0.02

84

Kr mols (10−18 ) 10.4 5.9 8.5 1.5 2.0 2.3 62 6.3 11.0

± ± ± ± ± ± ± ± ±

0.4 0.2 0.3 0.1 0.2 0.3 2 0.2 0.4

228 ± 4 28 38 30 21.9 23.5 16.4 6.7 51 13

± ± ± ± ± ± ± ± ±

1 2 1 0.8 1.3 0.6 0.4 2 1

227 ± 4 36 36 38 28 14.9 15.3 13.6 62 18.6

± ± ± ± ± ± ± ± ±

1 1 1 1 0.9 0.7 0.7 2 0.7

262 ± 4

57.6 37.8 18.6 10.9 7.2 3.8 46.1

± ± ± ± ± ± ±

1.0 0.6 0.3 0.3 0.1 0.2 1.7

182 ± 2 16.9 25.9 26.6 10.7 2.5 0.78 1.23 26.5 10.5

± ± ± ± ± ± ± ± ±

0.2 0.4 0.4 0.2 0.1 0.01 0.02 0.4 0.2

122 ± 1 8.3 44 24.5 10.0 5.7 1.4 3.8 27

± ± ± ± ± ± ± ±

0.4 2 0.9 0.4 0.5 0.1 0.2 1

129 Xe mols (10−18 )

0.91 0.58 0.70 0.22 0.1 0.28 2.7

± ± ± ± ± ± ±

0.03 0.04 0.03 0.03 0.1 0.05 0.1

0.41 ± 0.01 32 ± 1 14.2 22 11.2 4.9 3.2 2.1 1.5 1.9 0.9

± ± ± ± ± ± ± ± ±

0.7 1 0.4 0.9 0.3 0.2 0.2 0.3 0.1

62 ± 2 10.7 12.5 5.9 2.6

± ± ± ±

0.7 0.4 0.2 0.1

1.6 2.3 2.8 0.4

± ± ± ±

0.1 0.2 0.1 0.2

39 ± 1

18.3 4.1 1.5 0.2 1.1 0.3 2.0

± ± ± ± ± ± ±

0.7 0.2 0.1 0.2 0.1 0.1 0.1

27 ± 1 8.9 10.0 4.6 1.30 0.38 0.18 0.10 1.28 0.56

± ± ± ± ± ± ± ± ±

0.3 0.3 0.2 0.05 0.01 0.01 0.00 0.05 0.02

27 ± 1 5.0 17.9 5.6 1.5 1.2 0.3 0.49 2.2

± ± ± ± ± ± ± ±

0.1 0.5 0.1 0.2 0.1 0.1 0.01 0.1

Cl mols (10−9 ) 14.1 8.1 11.4 0.9 1.2 2.2 97 13.0 24

± ± ± ± ± ± ± ± ±

0.9 0.5 0.7 0.1 0.1 0.1 6 0.8 2

276 ± 8 3.8 39 54 51 59 17 20 197 58

± ± ± ± ± ± ± ± ±

0.3 3 4 3 4 1 1 13 4

500 ± 15 2.2 43 45 31 31 19 39 193 95

± ± ± ± ± ± ± ± ±

0.1 3 3 2 2 1 3 12 6

498 ± 15

31.9 35.9 17.6 11.1 4.6 3.5 71.9

± ± ± ± ± ± ±

0.6 0.7 0.3 0.2 0.1 0.1 1.4

177 ± 2 0.58 21.9 67.2 44.1 9.6 1.38 3.1 146.0 46.9

± ± ± ± ± ± ± ± ±

0.02 0.4 1.3 0.8 0.2 0.03 0.1 2.8 0.9

341 ± 3 1.2 27 20 14.1 6.0 0.69 3.6 48

± ± ± ± ± ± ± ±

0.1 2 1 0.9 0.4 0.05 0.2 3

Br/Cl (10−3 )

K mols (10−9 ) 0.06 ± 0.01 0.4 ± 0.1

0.06 4.1 0.59 1.05

± ± ± ±

0.04 0.1 0.01 0.01

2.8 ± 0.3 2.8 ± 0.3 3.1 ± 0.3 2.9 2.7 2.9 2.2 1.5

± ± ± ± ±

0.3 0.3 0.3 0.2 0.2

I/Cl (10−6 ) 16 16 12 3.1 6 12 14 10 22

± ± ± ± ± ± ± ± ±

2 2 1 0.3 1 1 1 1 2

9.4 ± 0.2

1.7 6.7 0.6 1.6 1.3 8.9 2.48

± ± ± ± ± ± ±

0.3 0.2 0.2 0.2 0.3 0.1 0.04

1.2 0.6 13.3 12.1 7.6

± ± ± ± ±

0.1 0.4 0.2 0.8 0.2

3.1 3.2 3.0 2.6 2.6 2.5 2.4 2.4 2.0

± ± ± ± ± ± ± ± ±

0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.2

3.7 11 9 10 8.8 6.6 6.1 7.8 5.1

± ± ± ± ± ± ± ± ±

0.6 1 1 1 0.9 0.8 0.7 0.8 0.5

± ± ± ± ± ± ±

0.03 0.04 0.04 0.02 0.1 0.01 0.1

3.2 3.2 3.1 3.1 3.3 2.8 3.0 2.6 2.1

± ± ± ± ± ± ± ± ±

0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.2

7.3 7.4 7.7 5.9 4.9 6.8 6.2 3.6

± ± ± ± ± ± ± ±

0.8 0.8 0.8 0.6 0.5 0.7 0.6 0.4

± ± ± ± ± ± ± ±

0.04 0.1 0.1 0.05 0.01 0.02 0.2 0.1

1.3 1.2 1.3 1.1 0.88 1.1 1.1

± ± ± ± ± ± ±

0.1 0.1 0.1 0.1 0.09 0.1 0.1

35 33 33 32 29 37 27

± ± ± ± ± ± ±

4 4 4 3 3 4 3

± ± ± ±

0.02 0.02 0.02 0.1

0.27 ± 0.01 3.9 ± 0.1

173 ± 166

550 488 555 324 169

± ± ± ± ±

75 49 77 41 74

1 ± 33 19 ± 19 445 ± 68 316 ± 41 565 ± 86 172 ± 42

269 1120 172 461

± ± ± ±

45 56 24 24

2021 ± 79 2.0 2.2 2.5 2.3 2.0 2.4 2.2 1.8 1.5

± ± ± ± ± ± ± ± ±

0.2 0.2 0.3 0.2 0.2 0.2 0.2 0.2 0.2

24 20 21 20 19 14 14 15 10

± ± ± ± ± ± ± ± ±

3 2 2 2 2 2 2 2 1

27.8 ± 0.2

0.97 0.49 0.60 0.5

22 23 5 1 16 25 258 160 1160

1519 ± 130

15.9 ± 0.2

1.27 3.6 2.7 0.84 0.03 0.21 14.2 5.0

± ± ± ± ± ± ± ± ±

2260 ± 220

35 ± 1

2.25 2.67 1.14 1.50 1.8 0.11 6.5

103 43 8 8 69 332 3631 2288 15816

22682 ± 1201

23 ± 1

0.2 ± 0.1

U mols (10−15 )

44 ± 3 117 ± 12 118 ± 6 278 ± 13

4.0 3.9 3.4 3.3 3.1 3.0 2.7 2.7

± ± ± ± ± ± ± ±

0.4 0.4 0.4 0.3 0.3 0.3 0.3 0.3

19 21 22 25 31 26 25 32

± ± ± ± ± ± ± ±

2 2 0 3 3 3 3 3

69 32 71 7

± ± ± ±

14 31 20 24

46 ± 19 165 ± 15 1226 ± 91

148

M.A. Kendrick et al. / Precambrian Research 163 (2008) 131–150

Cloncurry District 40

40

Ar mols (10−15 )

Arcorr mols (10−15 )

36

84

Ar mols (10−15 )

Kr mols (10−18 )

129 Xe mols (10−18 )

Cl mols (10−9 )

K mols (10−9 )

1600

1489 ± 1

1470 ± 4

0.54 ± 0.01

10.4 ± 0.4

1.8 ± 0.1

13.2 ± 0.9

1.13 ± 0.03

Total

15714 ± 7

15583 ± 22

4.87 ± 0.04

134 ± 2

36 ± 1

134 ± 4

7.8 ± 0.1

Knobby Quarry 02CC108, 81 mg 200 2154 ± 2 2161 300 10707 ± 9 10625 400 5056 ± 2 4993 500 2648 ± 3 2598 600 2183 ± 3 2158 700 1454 ± 2 1387 1100 1292 ± 1 1060 1400 3944 ± 1 3645 1600 2108 ± 1 1832 31546 ± 10

Total

57966 ± 21

6 30 10 9 8 6 4 8 7

1.46 2.71 1.8 1.2 1.3 0.2 0.44 1.3 1.05

30460 ± 37

Knobby Quarry 02CC38, 91 mg 200 1397 ± 2 1392 300 22950 ± 16 22803 400 7503 ± 6 7434 500 4960 ± 4 4901 600 3552 ± 3 3500 700 552.0 ± 0.3 519 1100 890 ± 1 840 1400 13062 ± 10 12684 1540 3100 ± 2 2960 Total

± ± ± ± ± ± ± ± ±

± ± ± ± ± ± ± ± ±

5 61 22 14 10 1 3 36 8

57032 ± 77

± ± ± ± ± ± ± ± ±

0.05 0.02 0.1 0.1 0.1 0.1 0.02 0.1 0.01

11.5 ± 0.2 0.81 3.64 1.24 1.08 0.57 0.10 0.211 3.36 0.77

± ± ± ± ± ± ± ± ±

0.01 0.03 0.01 0.02 0.01 0.01 0.002 0.03 0.01

11.77 ± 0.05

31 67 28.7 19.0 19.5 13.0 11.9 23 13.1

± ± ± ± ± ± ± ± ±

2 3 1.2 0.7 0.8 0.6 0.6 2 0.6

226 ± 4 18.9 70 25.9 18.1 12.7 3.3 3.8 59.1 8.9

± ± ± ± ± ± ± ± ±

0.3 1 0.4 0.3 0.3 0.1 0.1 0.9 0.5

221 ± 2

7.3 11.4 4.5 1.0 1.1 2.1 0.7 2.2 1.3

± ± ± ± ± ± ± ± ±

0.5 0.4 1.0 0.1 0.2 0.8 0.5 0.2 0.2

6.2 34 26 35 62 48 50 103 73

31 ± 2 4.4 7.1 2.55 1.21 0.78 0.29 0.27 2.44 1.01

± ± ± ± ± ± ± ± ±

± ± ± ± ± ± ± ± ±

0.4 2 2 2 4 3 3 7 5

4.9 3.8 3.0 1.5 4.0 13.8 17.9 16.5

438 ± 11

0.2 0.3 0.09 0.04 0.05 0.01 0.01 0.09 0.04

20.0 ± 0.4

1.17 35.3 25.7 24.8 24.6 5.1 7.4 140 48.7

± ± ± ± ± ± ± ± ±

± ± ± ± ± ± ± ±

Br/Cl (10−3 )

I/Cl (10−6 )

2.8 ± 0.3

23 ± 2

0.33 8.8 4.1 3.5 3.1 2.0 2.96 22.7 8.4

313 ± 3

± ± ± ± ± ± ± ± ±

412 ± 30 2028 ± 110

1.4 1.4 1.2 0.70 0.43 0.57 0.42 0.69 1.3

0.1 0.2 0.2 1.0 0.4 0.3 0.4 0.4

± ± ± ± ± ± ± ± ±

0.2 0.1 0.1 0.07 0.05 0.06 0.04 0.07 0.1

20 19 14 7.7 5.7 5.5 3.8 7.8 7.1

± ± ± ± ± ± ± ± ±

3 2 1 0.8 0.6 0.6 0.4 0.8 0.7

65 ± 1

0.02 0.7 0.5 0.5 0.5 0.1 0.1 3 0.9

U mols (10−15 )

228 ± 195 306 528 543 1366 1485 1067 1390

± ± ± ± ± ± ±

158 131 49 412 133 77 104

6913 ± 536

0.01 0.2 0.1 0.1 0.1 0.0 0.05 0.3 0.1

1.3 1.3 1.2 1.3 0.91 0.74 1.0 0.94 0.64

± ± ± ± ± ± ± ± ±

0.1 0.1 0.1 0.1 0.09 0.08 0.1 0.10 0.07

12 11 10 11 8.8 6.1 9 7.1 3.5

± ± ± ± ± ± ± ± ±

2 1 1 1 0.9 0.7 1 0.8 0.4

55.9 ± 0.4

133 ± 32 22 ± 14 78 18 142 218 151

± ± ± ± ±

24 2 9 21 8

762 ± 49

A.3. Noble gas and halogen in vacuo crushing data

Mary Kathleen Fold Belt 40

Ar mols (10−15 )

40

Arcorr mols (10−15 )

Tribulation Quarry 02CC05, 22 mg cr 1 887.3 ± 0.6 876 ± cr 2 988.2 ± 0.4 982 ± cr 3 405.0 ± 0.3 402 ± cr 4 325.1 ± 0.1 322.3 ± 2605.7 ± 0.8

2583 ± 3

Tribulation Quarry 02CC82, 34 mg Cr1 1428.9 ± 0.5 1413 ± Cr2 1949.1 ± 0.7 1913 ± Cr3 906.4 ± 0.5 854 ± Cr4 846.8 ± 0.5 847 ± 5131 ± 1

2 2 4 3

5536 ± 6

Knobby Quarry 02CC108, 26 mg Cr1 3219 ± 2 3194 Cr2 5052.7 ± 0.9 5031 Cr3 1404.1 ± 0.5 1347 Cr4 1951.7 ± 0.1 1920 11628 ± 2

3 4 2 2

5028 ± 6

Tribulation Quarry 02CC85, 47 mg Cr 1 1680.7 ± 0.1 1656 ± Cr 2 1833.8 ± 0.2 1838 ± Cr 3 966 ± 2 961 ± Cr 4 1081 ± 3 1081 ± 5561 ± 4

2 2 1 0.6

± ± ± ±

8 7 3 2

11491 ± 11

36

Ar mols (10−15 ) 2.2 1.3 0.8 0.3

± ± ± ±

84

0.2 0.1 0.1 0.1

4.6 ± 0.2 2.6 2.88 0.8 0.517

± ± ± ±

0.1 0.03 0.1 0.003

6.8 ± 0.1 2.99 2.5 1.11 0.86

± ± ± ±

0.02 0.1 0.01 0.02

7.5 ± 0.1 1.8 1.1 0.8 0.4

± ± ± ±

0.1 0.2 0.2 0.2

4.0 ± 0.3

Nb, these sample splits were not subjected to stepped heating.

Kr mols (10−18 )

37 35 16.9 13.8

± ± ± ±

2 2 0.6 0.5

102 ± 3 61 77 24 24

± ± ± ±

3 3 1 3

186 ± 5 58 47 22 21

± ± ± ±

2 2 1 1

148 ± 3 33 21.9 8.0 7.1

± ± ± ±

1 0.8 0.6 0.6

70 ± 2

129

Xe mols (10−18 ) Cl mols (10−9 ) K mols (10−9 ) Br/Cl (10−3 ) I/Cl (10−6 ) U mols (10−15 )

1.8 1.81 1.2 0.5

± ± ± ±

0.6 0.04 0.1 0.1

5.2 ± 0.6 3.1 2.4 0.7 2.9

± ± ± ±

0.4 0.1 0.1 0.1

9.2 ± 0.5 2.0 2.6 3.6 0.9

± ± ± ±

0.2 0.3 0.3 0.3

30 43 19 16

± ± ± ±

2 3 1 1

109 ± 4 79 105 63 62

± ± ± ±

5 7 4 4

± ± ± ±

0.2 0.1 0.01 0.01

0.92 ± 0.11 2.2 ± 0.1 3.1 ± 0.1 6.2 ± 0.2

± ± ± ±

1.5 ± 0.2

61 79 47 55

4 5 3 4

242 ± 8

1.2 ± 0.4 2.9 ± 0.2 0.7 ± 0.1

14.1 19 9.4 14.2

± ± ± ±

0.9 1 0.6 0.9

56 ± 2

3.9 3.1 2.7 2.9

± ± ± ±

0.4 0.3 0.3 0.3

12 16 14 13

± ± ± ±

1 2 1 1

1.3 ± 0.2

308 ± 10

9.1 ± 0.6

4.9 ± 0.5

0.7 0.3 0.15 0.17

0.3 ± 0.1

363 ± 98 4.6 3.8 3.7 3.8

± ± ± ±

0.5 0.4 0.4 0.4

10 13 10 11

± ± ± ±

1 1 1 1

± ± ± ±

0.02 0.1 0.5 0.3

8.2 ± 0.6

29 ± 97

29 ± 97 3.8 3.8 3.9 3.8

± ± ± ±

0.4 0.4 0.4 0.4

8 8 6 8

± ± ± ±

1 1 1 1

1.8 ± 0.2 1.54 1.3 3.4 1.9

115 ± 8 195 ± 19 53 ± 96

124 ± 29

124 ± 29 1.5 1.7 1.3 1.4

± ± ± ±

0.2 0.2 0.1 0.1

25 25 18 20

± ± ± ±

3 3 2 2

433 ± 62

433 ± 62

M.A. Kendrick et al. / Precambrian Research 163 (2008) 131–150

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