Sodium-calcium metasomatism; chemical, temporal, and spatial relationships at the Yerington, Nevada, porphyry copper deposit

Carten, Richard B.

doi:10.2113/gsecongeo.81.6.1495

Cited by 124 publications

(90 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In addition we have noted sodic-calcic hydrothermal alteration assemblages (Carten, 1979) in the Cornelia pluton. These assemblages, previously recognized in the deep zones beneath the Yerington (Carten, 1981) and Ann Mason (John Dilles, oral communication, 1983) porphyry copper deposits in Nevada also lend support to the hypothesis that the Cornelia pluton is the root zone of the Ajo porphyry copper system.…”

Section: Introductionsupporting

confidence: 62%

Maps showing rock types, hydrothermal alteration and distribution of fluid inclusions in the Cornelia Pluton, Ajo Mining district, Pima County, Arizona

Cox¹,

Ohta²

1984

Open-File Report

View full text Add to dashboard Cite

Section: Introductionsupporting

confidence: 62%

Maps showing rock types, hydrothermal alteration and distribution of fluid inclusions in the Cornelia Pluton, Ajo Mining district, Pima County, Arizona

Cox¹,

Ohta²

1984

Open-File Report

View full text Add to dashboard Cite

“…The pH is weakly acidic (6.05) at low fluid/rock ratios and, during transformation of aluminosilicates (cordierite and andalusite) to amphibole, it rises slightly to near-neutral values (6.6-6.7). The simulated alteration sequence reproduces all main features of sodic-calcic alteration, as observed, for example, in high-temperature portions of porphyry-copper systems (Carten, 1986;Dilles and Einaudi, 1992) or in deep-seated iron oxide-copper-gold systems (De Jong and Williams, 1995;Mark, 1998). Presence of albite-rich, amphibole-or clinopyroxene-bearing assemblages in nature can be used to place constraints on the fluid/rock ratios, pH and oxygen fugacity during alkali metasomatism (Fig.…”

Section: Interaction With a Low-temperature Multicomponent Brinementioning

confidence: 55%

Thermodynamic modeling of non-ideal mineral–fluid equilibria in the system Si–Al–Fe–Mg–Ca–Na–K–H–O–Cl at elevated temperatures and pressures: Implications for hydrothermal mass transfer in granitic rocks

Dolejš

Wagner

2008

Geochimica et Cosmochimica Acta

View full text Add to dashboard Cite

“…From shallow to deep, the alteration sequence is broadly zoned from proximal and shallow advanced argillic, underlain by sericitic, then potassic alteration with highest Cu grades. Sodic alteration is widely present at intermediate levels; propylitic alteration distally surrounds porphyry mineralization centers; and sodic-calcic (Na-Ca) alteration occurs at deep levels (3.5 to >6 km) (Carten 1986;Dilles et al 2000).…”

Section: Geologic Contextmentioning

confidence: 99%

“…Na-Ca alteration and coarse muscovite alteration postdates many aplite and pegmatite dikes in the Luhr Hill area. In the Yerington district, Na-Ca alteration reflects influx of externally derived brines that alternate 9 with expulsion of magmatic fluids (Carten 1986;Dilles et al , 2000. Timing relationships, therefore, suggest that coarse muscovite veins formed from fluids released late in the evolution of the batholith, between influxes of external brines.…”

Section: Paleodepths and Timing Of Fluid Releasementioning

confidence: 99%

Coarse muscovite veins and alteration deep in the Yerington batholith, Nevada: insights into fluid exsolution in the roots of porphyry copper systems

et al. 2017

View full text Add to dashboard Cite

Veins and pervasive wall-rock alteration composed of coarse muscovite±quartz±pyrite are documented for the first time in a porphyritic granite at Luhr Hill in the Yerington district, Nevada. Coarse muscovite at Luhr Hill occurs at paleodepths of ~6-7 km in the roots of a porphyry copper system and crops out on the scale of tens to hundreds of meters, surrounded by rock that is unaltered or variably altered to sodic-calcic assemblages. Coarse muscovite veins exhibit a consistent orientation, subvertical and N-S striking, which structurally restores to subhorizontal at the time of formation. Along strike, coarse muscovite veins swell from distal, mm-thick muscovite-only veinlets to proximal, cm-thick quartz-sulfide-bearing muscovite veins.Crosscutting relationships between coarse muscovite veins, pegmatite dikes, and sodic-calcic veins indicate that muscovite veins are late-stage magmatic-hydrothermal features predating final solidification of the Luhr Hill porphyritic granite. Fluid inclusions in the muscovite-quartz veins are high-density aqueous inclusions of ~3-9 wt% NaCl eq. and <1 mol% CO 2 that homogenize between ~150°C and 200°C, similar to fluid inclusions from greisen veins in Sn-W-Mo vein 2 systems. Our results indicate that muscovite-forming fluids at Luhr Hill were mildly acidic, of low to moderate salinity and sulfur content and low CO 2 content, and that muscovite in deep veins and alteration differs in texture, composition, and process of formation from sericite at shallower levels of the hydrothermal system. Although the definition of greisen is controversial, we suggest that coarse muscovite alteration is more similar to alteration in greisen-type Sn-WMo districts worldwide than to sericitic alteration at higher levels of porphyry copper systems.The fluids that form coarse muscovite veins and alteration in the roots of porphyry copper systems are distinct from fluids that formed copper ore or widespread, shallower, acidic alteration. We propose that this style of veins and alteration at Luhr Hill represents degassing of moderate volumes of overpressured hydrothermal fluid during late crystallization of deep levels of the Yerington batholith.

show abstract

Sodium-calcium metasomatism; chemical, temporal, and spatial relationships at the Yerington, Nevada, porphyry copper deposit

Cited by 124 publications

References 0 publications

Maps showing rock types, hydrothermal alteration and distribution of fluid inclusions in the Cornelia Pluton, Ajo Mining district, Pima County, Arizona

Maps showing rock types, hydrothermal alteration and distribution of fluid inclusions in the Cornelia Pluton, Ajo Mining district, Pima County, Arizona

Thermodynamic modeling of non-ideal mineral–fluid equilibria in the system Si–Al–Fe–Mg–Ca–Na–K–H–O–Cl at elevated temperatures and pressures: Implications for hydrothermal mass transfer in granitic rocks

Coarse muscovite veins and alteration deep in the Yerington batholith, Nevada: insights into fluid exsolution in the roots of porphyry copper systems

Contact Info

Product

Resources

About