Laser Raman Analyses and Total Fluid Inclusion Contents

 

S Javad Moghaddasi

I-Ming Chou

Pam Murphy

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Dear all

Referring the application of Laser Raman spectroscopic analysis in the study of fluid inclusions, I have used the LRS analysis to get the composition of the volatile phases in fluid inclusions in my own research area (Tongshankou porphyry copper deposit, Hubei, China). CO2 was the only gas I found in the vapor bubbles. Other gas species, such as CH4, CO, SO2, N2 were not detected. It would be possible to determine the molar proportions of the species in a multicomponent system, but my question is that how can I estimate or determine the molar concentration of CO2 in my samples?

I would appreciate all the members of the discussion group give me some advice or references.

Regards,

Javad

S Javad Moghaddasi
China University of Geosciences
College of Earth Resources
Yujiashan, Wuhan, Hubei
430074, China
Tel: +86 27 87515816
Fax: +86 27 87481364
E-mail: javad@dns.cug.edu.cn

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Dear Javad:

Please refer to the following papers:

Seitz, Pasteris, and Chou, Am. J. Sci., vol. 296, 577-600, 1996 (especially Tables 2 and 3, Figs. 1B and 1C).

Rosso and Bodnar, Geochim. Cosmochim. Acta, 59(19), 3961-3975, 1993.

Barton amd Chou, Geochim. Cosmochim. Acta, 57, 2715-2723.

Barton and Chou, Economic Geology, 88, 873-884, 1993.

Good luck!

I-Ming Chou

954 National Center
 U.S. Geological Survey
 Reston, VA 20192
 U.S.A.
Phone: +1 (703)648-6169
Fax: +1 (703)648-6383 or
 +1 (703) 648-6252
E-mail: imchou@usgs.gov

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Raman can tell you the relative molar proportions of the gases present, it can't tell you the absolute amount, and it can't tell you the proportion of water present. If you have water in the inclusions, you must calculate the molar proportions of aqueous and gas/carbonic phases from your microthermometry and volume data (together with Raman data on the gas composition). This is true whether your carbonic phase is 100% CO2 or mixed CO2-N2-CH4-whatever.

The references I-Ming suggested are a good place to start. Have fun.

Pam

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Dr Pamela Murphy
Centre for Earth and Environmental Science Research
School of Geological Sciences, Kingston University
Kingston upon Thames, Surrey, KT1 2EE, UK
Tel. 0181 547 2000 x2528 Fax 0181 547 7497
GL_S553@crystal.kingston.au.uk