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U.S. Geological Survey Open-File Report 2004-1066
Online Version 1.0

Homogenization Temperature and Salinity Data for Fluid Inclusions from the Summitville, Colorado, Cu-Au-Ag Deposit

By Roger E. Stoffregen,1 Peter Vikre,2 and Philip M. Bethke3

1305 Swissvale Avenue, Pittsburgh, PA 15218.
2U.S. Geological Survey, Reno, NV 89557.
3U.S. Geological Survey, Reston, VA 2019

Introduction

The Appendix to this report presents a table of homogenization temperature and salinity data (as weight percent NaCl equivalent) on individual fluid inclusions from the high-sulfidation Cu-Au-Ag deposit at Summitville, Colorado. The data supplement Table 2 in Bethke and others (2004) in which the data are only summarized.

Samples

Samples for fluid inclusion analysis were from outcrops, diamond drill cores, dumps, and mine benches. Their coordinates (northing and easting) and elevation, where known, are listed with the fluid inclusion data in the Appendix. The coordinates are those shown on Figure 2 of Bethke and others (2004). Samples noted by hyphenated numbers were taken from diamond drill core, the first number denoting the drill hole and the second the down-hole footage (uncorrected for plunge). The coordinates and elevations of the diamond drill core samples are based on data for the surveyed locations of the collar and plunge and azimuth of the holes supplied by the Summitville Consolidated Mining Company (M. Coolbaugh, written communication, 1991) and on logged core footages corrected for the azimuth and declination of the drill hole. The coordinates of surface and dump samples are less well known. Their elevations are constrained within a few meters but the uncertainties in their northing and easting coordinates may be substantial. If the approximate coordinates of surface and dump samples are known within ±20 meters, they are noted in italics. Otherwise, no entry is listed. Mine areas noted in the Appendix are shown in Figure 2 of Bethke and others (2004). The Appendix is in Microsoft Excel™ format.

Measurements

Thermometric data on fluid inclusions were obtained using a USGS-design gas-flow heating-cooling stage (Werre and others, 1980). Homogenization of inclusions to liquid (L) or vapor (V) on heating is indicated in the Appendix. Estimated precision of heating measurements (Th) was ±5°C, and was ±0.5°C for measurements of freezing-point depression (Tm). Measurements on samples 14–3498, 14–4734, and SV79–1 were made by Vikre on fluid inclusions in vein quartz. All other measurements were made on secondary fluid inclusions in quartz phenocrysts in the host South Mountain Quartz Latite by Stoffregen with the exception of sample 293–37 which was measured by Greg Symmes. Salinity (weight percent NaCl equivalent) values were estimated from freezing point depression measurements (Tm) using the equation of Bodnar (1993) and, for saturated fluid inclusions, from NaCl dissolution (Ts) based the data for NaCl-H2O binary system by Sourirajan and Kennedy (1962).

References

Bethke, P.M., Rye, R.O., Stoffregen R.E. and Vikre, P.G., 2004, Evolution of the magmatic-hydrothermal acid-sulfate system at Summitville, Colorado: Integration of geological, stable-isotope, and fluid-inclusion evidence: Chemical Geology, v. 215, p. 281–315.

Bodnar, R.J., 1993, Revised equation and table for determining the freezing point depression of H2O-NaCl solutions: Geochimica et Cosmochimica Acta, v. 57, p. 683–684.

Sourirajan, S., and Kennedy, G.C., 1962, The system H2O–NaCl at elevated temperatures and pressures: American Journal of Science, v. 260, p. 115–141.

Werre, R.W., Jr., Bodnar, R.J., Bethke, P.M., and Barton, P.B., Jr., 1980, Novel heating-freezing fluid inclusion stage: U. S. Geological Survey Professional Paper 1175, p. 190.


U.S. Department of the Interior, U.S. Geological Survey
URL: http://pubsdata.usgs.gov/pubs/of/2004/1066/of2004-1066.html
For more information, contact Philip M. Bethke
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