The speciation of mercury in hydrothermal systems, with applications to ore deposition

Johan C. Varekamp, P R Buseck

Research output: Contribution to journalArticle

77 Citations (Scopus)

Abstract

Hg in hydrothermal systems is generally thought to be transported as Hg-S complexes. However, the abundance of Hg0 vap, in geothermal emissions suggests that Hg0 eq, is present in the liquid phase of geothermal systems. Calculations for reducing fluids (HS- dominant over SO= 4) in equilibrium with cinnabar indicate that Hg0 eq, can be quite abundant relative to other species at temperatures above 200°C. Increasing pH and temperature, and decreasing total S, ionic strength, and pO2 all promote the abundance of Hg0 eq. When a vapor phase develops from a geothermal liquid, Hg partitions strongly into the vapor as Hg0 vap. Vapor transport at shallow level then results in the formation of Hg halos around shallow aquifers as well as in a flux of Hg to the atmosphere. Hg deposition may occur in response to mixing with oxidizing or acidic water, turning Hg0 eq, into Hg++, with subsequent cinnabar precipitation. When pyrite is the stable Fe-sulfide, cinnabar solubility is at its lowest, so cinnabar + pyrite assemblages are common. Cinnabar + hematite ± pyrite can precipitate from more oxidized or S-poor water. Hg0 liq, can occur as a primary mineral, in coexistence with all common Fe-sulfides and oxides. Cinnabar ± Hg0 liq cannot coexist with pyrrhotite or magnetite at temperatures between 100° and 250°C. Evidence from Hg deposits indicates that many formed from dilute hydrothermal fluids in which Hg probably occurred as Hg0 eq. In S-rich systems, Hg may occur as Hg-S complexes, and in saline waters it can occur as Hg-Cl complexes.

Original languageEnglish (US)
Pages (from-to)177-185
Number of pages9
JournalGeochimica et Cosmochimica Acta
Volume48
Issue number1
DOIs
StatePublished - 1984

Fingerprint

cinnabar
hydrothermal system
Mercury
Ores
pyrite
Vapors
Sulfides
sulfide
Ferrosoferric Oxide
liquid
Fluids
Water
temperature
geothermal system
Liquids
pyrrhotite
Ionic strength
hydrothermal fluid
Aquifers
water

ASJC Scopus subject areas

  • Geochemistry and Petrology

Cite this

The speciation of mercury in hydrothermal systems, with applications to ore deposition. / Varekamp, Johan C.; Buseck, P R.

In: Geochimica et Cosmochimica Acta, Vol. 48, No. 1, 1984, p. 177-185.

Research output: Contribution to journalArticle

@article{049f0ae55f63453c85b65a4a98ba88f0,
title = "The speciation of mercury in hydrothermal systems, with applications to ore deposition",
abstract = "Hg in hydrothermal systems is generally thought to be transported as Hg-S complexes. However, the abundance of Hg0 vap, in geothermal emissions suggests that Hg0 eq, is present in the liquid phase of geothermal systems. Calculations for reducing fluids (HS- dominant over SO= 4) in equilibrium with cinnabar indicate that Hg0 eq, can be quite abundant relative to other species at temperatures above 200°C. Increasing pH and temperature, and decreasing total S, ionic strength, and pO2 all promote the abundance of Hg0 eq. When a vapor phase develops from a geothermal liquid, Hg partitions strongly into the vapor as Hg0 vap. Vapor transport at shallow level then results in the formation of Hg halos around shallow aquifers as well as in a flux of Hg to the atmosphere. Hg deposition may occur in response to mixing with oxidizing or acidic water, turning Hg0 eq, into Hg++, with subsequent cinnabar precipitation. When pyrite is the stable Fe-sulfide, cinnabar solubility is at its lowest, so cinnabar + pyrite assemblages are common. Cinnabar + hematite ± pyrite can precipitate from more oxidized or S-poor water. Hg0 liq, can occur as a primary mineral, in coexistence with all common Fe-sulfides and oxides. Cinnabar ± Hg0 liq cannot coexist with pyrrhotite or magnetite at temperatures between 100° and 250°C. Evidence from Hg deposits indicates that many formed from dilute hydrothermal fluids in which Hg probably occurred as Hg0 eq. In S-rich systems, Hg may occur as Hg-S complexes, and in saline waters it can occur as Hg-Cl complexes.",
author = "Varekamp, {Johan C.} and Buseck, {P R}",
year = "1984",
doi = "10.1016/0016-7037(84)90359-4",
language = "English (US)",
volume = "48",
pages = "177--185",
journal = "Geochmica et Cosmochimica Acta",
issn = "0016-7037",
publisher = "Elsevier Limited",
number = "1",

}

TY - JOUR

T1 - The speciation of mercury in hydrothermal systems, with applications to ore deposition

AU - Varekamp, Johan C.

AU - Buseck, P R

PY - 1984

Y1 - 1984

N2 - Hg in hydrothermal systems is generally thought to be transported as Hg-S complexes. However, the abundance of Hg0 vap, in geothermal emissions suggests that Hg0 eq, is present in the liquid phase of geothermal systems. Calculations for reducing fluids (HS- dominant over SO= 4) in equilibrium with cinnabar indicate that Hg0 eq, can be quite abundant relative to other species at temperatures above 200°C. Increasing pH and temperature, and decreasing total S, ionic strength, and pO2 all promote the abundance of Hg0 eq. When a vapor phase develops from a geothermal liquid, Hg partitions strongly into the vapor as Hg0 vap. Vapor transport at shallow level then results in the formation of Hg halos around shallow aquifers as well as in a flux of Hg to the atmosphere. Hg deposition may occur in response to mixing with oxidizing or acidic water, turning Hg0 eq, into Hg++, with subsequent cinnabar precipitation. When pyrite is the stable Fe-sulfide, cinnabar solubility is at its lowest, so cinnabar + pyrite assemblages are common. Cinnabar + hematite ± pyrite can precipitate from more oxidized or S-poor water. Hg0 liq, can occur as a primary mineral, in coexistence with all common Fe-sulfides and oxides. Cinnabar ± Hg0 liq cannot coexist with pyrrhotite or magnetite at temperatures between 100° and 250°C. Evidence from Hg deposits indicates that many formed from dilute hydrothermal fluids in which Hg probably occurred as Hg0 eq. In S-rich systems, Hg may occur as Hg-S complexes, and in saline waters it can occur as Hg-Cl complexes.

AB - Hg in hydrothermal systems is generally thought to be transported as Hg-S complexes. However, the abundance of Hg0 vap, in geothermal emissions suggests that Hg0 eq, is present in the liquid phase of geothermal systems. Calculations for reducing fluids (HS- dominant over SO= 4) in equilibrium with cinnabar indicate that Hg0 eq, can be quite abundant relative to other species at temperatures above 200°C. Increasing pH and temperature, and decreasing total S, ionic strength, and pO2 all promote the abundance of Hg0 eq. When a vapor phase develops from a geothermal liquid, Hg partitions strongly into the vapor as Hg0 vap. Vapor transport at shallow level then results in the formation of Hg halos around shallow aquifers as well as in a flux of Hg to the atmosphere. Hg deposition may occur in response to mixing with oxidizing or acidic water, turning Hg0 eq, into Hg++, with subsequent cinnabar precipitation. When pyrite is the stable Fe-sulfide, cinnabar solubility is at its lowest, so cinnabar + pyrite assemblages are common. Cinnabar + hematite ± pyrite can precipitate from more oxidized or S-poor water. Hg0 liq, can occur as a primary mineral, in coexistence with all common Fe-sulfides and oxides. Cinnabar ± Hg0 liq cannot coexist with pyrrhotite or magnetite at temperatures between 100° and 250°C. Evidence from Hg deposits indicates that many formed from dilute hydrothermal fluids in which Hg probably occurred as Hg0 eq. In S-rich systems, Hg may occur as Hg-S complexes, and in saline waters it can occur as Hg-Cl complexes.

UR - http://www.scopus.com/inward/record.url?scp=0021366566&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0021366566&partnerID=8YFLogxK

U2 - 10.1016/0016-7037(84)90359-4

DO - 10.1016/0016-7037(84)90359-4

M3 - Article

AN - SCOPUS:0021366566

VL - 48

SP - 177

EP - 185

JO - Geochmica et Cosmochimica Acta

JF - Geochmica et Cosmochimica Acta

SN - 0016-7037

IS - 1

ER -