Pressure sensitive "silica geothermometer" determined from quartz solubility experiments at 250 °C

Kristín Vala Ragnarsdóttir; John V. Walther

doi:10.1016/0016-7037(83)90159-X

Pressure sensitive "silica geothermometer" determined from quartz solubility experiments at 250 °C

Kristín Vala Ragnarsdóttir^*, John V. Walther

^*Corresponding author for this work

Faculty of Earth Sciences

Research output: Contribution to journal › Article › peer-review

34 Citations (Scopus)

Abstract

Experimentally reversed quartz solubilities at 250°C and at 250, 500 and 1000 bars yield values of the logarithm of the molality of aqueous silica of -2.126, -2.087 and -2.038, respectively. Extrapolation of quartz solubility to the saturation pressure of water at 250°C results in a log molality of aqueous silica of-2.168. These solubility determinations and analyses of fluid pressures in geothermal systems indicate that pressure is significant when calculating quartz equilibrium temperatures from silica concentrations in waters of deep thermal reservoirs. The results of this investigation, combined with other reported quartz solubility measurements, yielded a pressure-sensitive "silica geothermometer" for fluids that have undergone adiabatic steam loss of t°C = 874 - 0.156P (log m_{Si(OH)₄ · 2H₂O})² + 411 log m_Si(OH4 · 2H₂O + 51 (log m_Si(OH)₄ · 2H₂O)² where P is the fluid pressure in bars and m_Si(OH)₄ · 2H₂O represents the molality of aqueous silica measured in surface samples. The geothermometer is applicable to solutions in equilibrium with quartz from 180°C to 340°C and fluid pressures from H₂O saturation to 500 bars.

Original language	English
Pages (from-to)	941-946
Number of pages	6
Journal	Geochimica et Cosmochimica Acta
Volume	47
Issue number	5
DOIs	https://doi.org/10.1016/0016-7037(83)90159-X
Publication status	Published - May 1983

Bibliographical note

Funding Information:
Acknowledgements-The research reported here represents part of the senior author’s Ph.D. dissertation at North-western University. We wish to thank Drs. S. Arnorsson, R. 0. Fournier and an anonymous reviewer for critically reviewing the paper. We would like to acknowledge Cheril Cheverton for drafting figures and especially for her limitless love and support. This project was supported by NSF grants EAR79-04892 and EAR80-24146 and the Margaret Fuller Boos fellowship fund.

Access to Document

10.1016/0016-7037(83)90159-X

Cite this

@article{2d763ff27e79420fb78f5478a2194a7e,

title = "Pressure sensitive {"}silica geothermometer{"} determined from quartz solubility experiments at 250 °C",

abstract = "Experimentally reversed quartz solubilities at 250°C and at 250, 500 and 1000 bars yield values of the logarithm of the molality of aqueous silica of -2.126, -2.087 and -2.038, respectively. Extrapolation of quartz solubility to the saturation pressure of water at 250°C results in a log molality of aqueous silica of-2.168. These solubility determinations and analyses of fluid pressures in geothermal systems indicate that pressure is significant when calculating quartz equilibrium temperatures from silica concentrations in waters of deep thermal reservoirs. The results of this investigation, combined with other reported quartz solubility measurements, yielded a pressure-sensitive {"}silica geothermometer{"} for fluids that have undergone adiabatic steam loss of t°C = 874 - 0.156P (log mSi(OH)4 · 2H2O)2 + 411 log mSi(OH4 · 2H2O + 51 (log mSi(OH)4 · 2H2O)2 where P is the fluid pressure in bars and mSi(OH)4 · 2H2O represents the molality of aqueous silica measured in surface samples. The geothermometer is applicable to solutions in equilibrium with quartz from 180°C to 340°C and fluid pressures from H2O saturation to 500 bars.",

author = "{Vala Ragnarsd{\'o}ttir}, Krist{\'i}n and Walther, {John V.}",

note = "Funding Information: Acknowledgements-The research reported here represents part of the senior author{\textquoteright}s Ph.D. dissertation at North-western University. We wish to thank Drs. S. Arnorsson, R. 0. Fournier and an anonymous reviewer for critically reviewing the paper. We would like to acknowledge Cheril Cheverton for drafting figures and especially for her limitless love and support. This project was supported by NSF grants EAR79-04892 and EAR80-24146 and the Margaret Fuller Boos fellowship fund.",

year = "1983",

month = may,

doi = "10.1016/0016-7037(83)90159-X",

language = "English",

volume = "47",

pages = "941--946",

journal = "Geochimica et Cosmochimica Acta",

issn = "0016-7037",

publisher = "Elsevier Ltd.",

number = "5",

}

TY - JOUR

T1 - Pressure sensitive "silica geothermometer" determined from quartz solubility experiments at 250 °C

AU - Vala Ragnarsdóttir, Kristín

AU - Walther, John V.

N1 - Funding Information: Acknowledgements-The research reported here represents part of the senior author’s Ph.D. dissertation at North-western University. We wish to thank Drs. S. Arnorsson, R. 0. Fournier and an anonymous reviewer for critically reviewing the paper. We would like to acknowledge Cheril Cheverton for drafting figures and especially for her limitless love and support. This project was supported by NSF grants EAR79-04892 and EAR80-24146 and the Margaret Fuller Boos fellowship fund.

PY - 1983/5

Y1 - 1983/5

N2 - Experimentally reversed quartz solubilities at 250°C and at 250, 500 and 1000 bars yield values of the logarithm of the molality of aqueous silica of -2.126, -2.087 and -2.038, respectively. Extrapolation of quartz solubility to the saturation pressure of water at 250°C results in a log molality of aqueous silica of-2.168. These solubility determinations and analyses of fluid pressures in geothermal systems indicate that pressure is significant when calculating quartz equilibrium temperatures from silica concentrations in waters of deep thermal reservoirs. The results of this investigation, combined with other reported quartz solubility measurements, yielded a pressure-sensitive "silica geothermometer" for fluids that have undergone adiabatic steam loss of t°C = 874 - 0.156P (log mSi(OH)4 · 2H2O)2 + 411 log mSi(OH4 · 2H2O + 51 (log mSi(OH)4 · 2H2O)2 where P is the fluid pressure in bars and mSi(OH)4 · 2H2O represents the molality of aqueous silica measured in surface samples. The geothermometer is applicable to solutions in equilibrium with quartz from 180°C to 340°C and fluid pressures from H2O saturation to 500 bars.

AB - Experimentally reversed quartz solubilities at 250°C and at 250, 500 and 1000 bars yield values of the logarithm of the molality of aqueous silica of -2.126, -2.087 and -2.038, respectively. Extrapolation of quartz solubility to the saturation pressure of water at 250°C results in a log molality of aqueous silica of-2.168. These solubility determinations and analyses of fluid pressures in geothermal systems indicate that pressure is significant when calculating quartz equilibrium temperatures from silica concentrations in waters of deep thermal reservoirs. The results of this investigation, combined with other reported quartz solubility measurements, yielded a pressure-sensitive "silica geothermometer" for fluids that have undergone adiabatic steam loss of t°C = 874 - 0.156P (log mSi(OH)4 · 2H2O)2 + 411 log mSi(OH4 · 2H2O + 51 (log mSi(OH)4 · 2H2O)2 where P is the fluid pressure in bars and mSi(OH)4 · 2H2O represents the molality of aqueous silica measured in surface samples. The geothermometer is applicable to solutions in equilibrium with quartz from 180°C to 340°C and fluid pressures from H2O saturation to 500 bars.

UR - http://www.scopus.com/inward/record.url?scp=0021092005&partnerID=8YFLogxK

U2 - 10.1016/0016-7037(83)90159-X

DO - 10.1016/0016-7037(83)90159-X

M3 - Article

AN - SCOPUS:0021092005

SN - 0016-7037

VL - 47

SP - 941

EP - 946

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

IS - 5

ER -

Pressure sensitive "silica geothermometer" determined from quartz solubility experiments at 250 °C

Abstract

Bibliographical note

Access to Document

Fingerprint

Cite this