Halogen chemistry as an indicator of metamorphic fluid interaction with the Ponder pluton, Coast Plutonic Complex, British Columbia, Canada

Sisson, Virginia B.

doi:10.1007/bf00518035

Cited by 35 publications

(10 citation statements)

References 33 publications

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“…Fugacities of the halogens Cl and F can be constrained by mineral reactions involving halogen-bearing biotite and apatite. Halogen contents of metamorphic biotites are functions of the fugacities of HCl and HF, and other parameters including temperature and Mg/Fe ratios (Munoz and Ludington, 1974;Munoz, 1984Munoz, , 1992Sisson, 1987;Zhu and Sverjensky, 1992). Using the phlogopite composition in Table 4 and the equilibrium metamorphic temperature of 670°C, we applied the formulations of Munoz (1992) to calculate average log(f HF / f H 2 O ) = À5.8, log(f HCl / f H 2 O ) = À3.3, and log(f HCl /f HF ) = À2.6.…”

Section: Other Volatile Fugacitiesmentioning

confidence: 99%

The LaPaz Icefield 04840 meteorite: Mineralogy, metamorphism, and origin of an amphibole- and biotite-bearing R chondrite

McCanta

Treiman

Dyar

et al. 2008

Geochimica et Cosmochimica Acta

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Section: Other Volatile Fugacitiesmentioning

confidence: 99%

The LaPaz Icefield 04840 meteorite: Mineralogy, metamorphism, and origin of an amphibole- and biotite-bearing R chondrite

McCanta

Treiman

Dyar

et al. 2008

Geochimica et Cosmochimica Acta

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“…Primary muscovite + quartz have not been found. Unlike areas of the Central Gneiss Complex farther north [ Crawford et al , 1987; Hollister , 1975; Sisson , 1985], staurolite has not been found in garnet cores or in matrix assemblages, and andalusite is absent. Fe‐Ti oxides and accessory minerals are present in all rocks.…”

Section: Evolution Of the Central Gneiss Complex On Douglas Channelmentioning

confidence: 99%

Two‐stage exhumation of midcrustal arc rocks, Coast Mountains, British Columbia

2005

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New geologic data from the Central Gneiss Complex along Douglas Channel help delineate the burial and exhumation of the Late Cretaceous to Eocene Coast Mountains magmatic arc. Arc plutonism was on going between ∼90 and 60 Ma, replaced by formation of dikes to 52 Ma. Supracrustal rocks were buried to midcrustal levels by 90 Ma, and garnet and kyanite grew from ∼90 through 70 Ma. Subsequent exhumation was nearly isothermal and took place in two stages. The first occurred from ∼70 to 59 Ma as the arc contracted obliquely and sillimanite replaced kyanite. Exhumation was slow (∼0.5 mm/yr), probably accomplished by erosion aided by coaxial crustal thinning. Exhumation rates about doubled in the second stage of exhumation, after 59 Ma and before ∼52 Ma. Penetrative deformation ended prior to intrusion of the Quottoon pluton at 59 Ma and ∼6.5 kbar. Production of cordierite rims on garnet at 4.5 kbar and ∼700°C signaled the end of near‐isothermal decompression prior to 52 Ma. Rapid cooling (100°C/106 years) of the Central Gneiss Complex followed cordierite growth; temperatures dropped to ∼250° by ∼48 Ma. The increase in exhumation rate and the subsequent rapid cooling are attributed to excision of >6 km of crust on a detachment system on the northeastern side of the Central Gneiss Complex. Comparison to other parts of the Coast Mountains arc, the Sierra Nevada, and Fiordland, New Zealand, shows that the amount and tempo of exhumation vary greatly within and between arcs, suggesting that the processes accommodating exhumation vary significantly.

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“…1c). Pure or nearly pure F-, OH-, and Cl-apatites, as well Kapustin (1987) Pyle (2001) Sisson (1987) Bea & Montero (1999) Yardley (1985) a OH Cl F Metasediments 14 Number of analyses in group Nijland et al (1998) Compositions measured in this study of apatite in metamorphosed siliceous carbonate rock from the Ballachulish, Beinn an Dubhaich, Monzoni, and Predazzo aureoles and the Ritter Range pendant. Each symbol represents one analysis.…”

Section: Methodsmentioning

confidence: 98%

“…Activity ratios a HCl /a H 2 O and a HF /a H 2 O were fi rst computed from measured apatite compositions using the equilibria 1985;Sisson 1987;Dipple and Ferry 1992;Nijland et al 1993). Equilibrium constants for equilibria 4 and 5 were calculated for the peak metamorphic P-T conditions of each sample using SUPCRT92 (Johnson et al 1992), with thermodynamic properties of apatite consistent with the data of Berman (1988Berman ( , 1990 Table 1.…”

Section: Activity Ratiosmentioning

confidence: 99%

Coupled dichotomies of apatite and fluid composition during contact metamorphism of siliceous carbonate rocks

Penniston‐Dorland

Ferry

2005

American Mineralogist

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The X CO 2 recorded by mineral-fl uid equilibria in contact metamorphosed siliceous carbonates commonly defi nes two groups of rocks in the same aureole. One group records relatively low X CO 2 that results from infi ltration of chemically reactive H 2 O-rich fl uid. The other records relatively high X CO 2 , up to 0.99, that results from decarbonation reactions with little or no infi ltration. A complementary dichotomy in apatite compositions exists in fi ve contact aureoles in Italy, Scotland, and the U.S.A. Apatite in the low-X CO 2 group is close to an F-OH solid solution. Apatite in the high-X CO 2 group is a relatively Cl-rich Cl-F-OH solution. The halogen content of fl uid coexisting with analyzed apatite was characterized in two aureoles to determine the origin and signifi cance of the dichotomy in apatite composition. Calculated a HF /a H 2 O , a HF /a HCl , a HF , and m F T (the total F molality of fl uid) are systematically higher in fl uid coexisting with the low-X CO 2 group. In contrast, a HCl /a H 2 O in the high-X CO 2 group may be higher than or overlap with a HCl /a H 2 O in the low-X CO 2 group. Calculated a HCl and m Cl T in the high-X CO 2 group are lower than or overlap with a HCl and m Cl T in the low-X CO 2 group. The Cl-rich apatites in the high-X CO 2 group are explained by crystallization at relatively low a H 2 O , a HF , and m F T rather than at high a HCl or m Cl T . In comparison, the F-OH apatites in the low-X CO 2 group formed by infi ltration of rock by and equilibration with relatively H 2 O-rich, high m F T /m Cl T fl uid, refl ecting the same metasomatic process responsible for F-rich humite-group minerals and skarns in many contact aureoles. Calculated halogen contents indicate that the non-CO 2 fraction of fl uid in equilibrium with both groups had modest, seawater-like salinity, and that the reactive H 2 O-and F-rich fl uid that infi ltrated the low-X CO 2 group had a plutonic source. Rock groupLow-X CO 2 High-X CO 2 X CO 2 0.13-0.28 0.96-0.99 Poorly constrained Notes: Retrograde minerals listed in italics. Minerals in bold formed during both prograde and retrograde metamorphism. Retrograde brucite formed after peak periclase. Mineral abbreviations: Act = actinolite, Ap = apatite, Bad baddeleyite, Brc = brucite, Cal = calcite, Cam = calcic amphibole, Chl = chlorite, Chn = chondrodite, Chu = clinohumite, Czo = clinozoisite, Di = diopside, Dol = dolomite, Fo = forsterite, Gk = geikielite, Gr = grossular, Hu = humite, Kfs = K-feldspar, Mag = magnetite, Ms = muscovite, Nrb = norbergite, Phl = phlogopite, Pl = plagioclase, Po = pyrrhotite, Prg = pargasite, Py = pyrite, Qnd = qandalite, Qtz = quartz, Rt = rutile, Scp = scapolite, Spl = spinel, Srp = serpentine, Tr = tremolite, Ttn = titanite, Urn = uraninite; Wo = wollastonite, Zrn = zircon.

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Halogen chemistry as an indicator of metamorphic fluid interaction with the Ponder pluton, Coast Plutonic Complex, British Columbia, Canada

Cited by 35 publications

References 33 publications

The LaPaz Icefield 04840 meteorite: Mineralogy, metamorphism, and origin of an amphibole- and biotite-bearing R chondrite

The LaPaz Icefield 04840 meteorite: Mineralogy, metamorphism, and origin of an amphibole- and biotite-bearing R chondrite

Two‐stage exhumation of midcrustal arc rocks, Coast Mountains, British Columbia

Coupled dichotomies of apatite and fluid composition during contact metamorphism of siliceous carbonate rocks

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