Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Heinrich, C. A. Search for Related Content GeoRef GeoRef Citation

Fluid-Fluid Interactions in Magmatic-Hydrothermal Ore Formation

Isotope Geochemistry and Mineral Resources, Department of Earth Sciences, ETH Zürich 8092 Zürich, Switzerland, heinrich@erdw.ethz.ch

The first 20% of the full text of this article appears below.

	INTRODUCTION

 
Hydrothermal ore deposits have provided some of the first geological evidence for the interaction of multiple fluids in the Earth’s interior, including fluid mixing as well as fluid phase separation. Physical evidence comes from veins and breccias documenting the impact of fluids in breaking rocks and creating fracture permeability for ore formation, as a result of the fluid expansion that is commonly associated with phase separation between melts and multiple fluids. Chemical evidence of fluid–fluid interaction includes the precipitation of minerals in veins as a result of fluid boiling or mixing between chemically contrasting fluids. Fluid inclusions record interactions of multiple fluids, especially in magmatic-hydrothermal ore deposits and associated igneous rocks (Fig. 1). In recent years, fluid inclusions have contributed to a more quantitative understanding of the role of fluid–fluid interactions, since new microanalytical techniques allow determination of element concentrations in all types of fluids, from low-density vapor through aqueous and hypersaline liquids to hydrous salt melts (Roedder 1984; Samson et al. 2003).

View larger version (73K):   Figure 1. Geological evidence for fluid phase separation in ore-forming magmatic-hydrothermal systems. (a) ‘Bonanza grade’ gold (1 wt%) that was precipitated together with fine-grained pyrite in a fluidized breccia resulting from instantaneous boiling and expansion of magmatic fluids ascending from an underlying andesite porphyry intrusion. The breccia consists of adularia–sericite altered clasts of sedimentary wall rock (s) and nodules of (originally colloidal?) pyrite with bright specks of gold (p+g), both cemented by roscoelite (r; vanadium-rich muscovite) and late calcite (c) (Zone VII ore body, Porgera, Papua New Guinea; Ronacher et al. 2004). (b) Bladed manganocalcite, the characteristic habit of calcite precipitated from aqueous epithermal fluids as a result of the pH change following loss of CO2 to a separating vapor phase (Madan, Bulgaria; Kostova et al. 2004). (c) Growth band in a . . . [Full Text of this Article]

This article has been cited by other articles:

				A. Liebscher and C. A. Heinrich Fluid Fluid Interactions in the Earth's Lithosphere Reviews in Mineralogy and Geochemistry, July 1, 2007; 65(1): 1 - 13. [Full Text] [PDF]

				A. Liebscher Experimental Studies in Model Fluid Systems Reviews in Mineralogy and Geochemistry, July 1, 2007; 65(1): 15 - 47. [Full Text] [PDF]

				A. C. Hack, A. B. Thompson, and M. Aerts Phase Relations Involving Hydrous Silicate Melts, Aqueous Fluids, and Minerals Reviews in Mineralogy and Geochemistry, July 1, 2007; 65(1): 129 - 185. [Full Text] [PDF]

				T. Driesner and S. Geiger Numerical Simulation of Multiphase Fluid Flow in Hydrothermal Systems Reviews in Mineralogy and Geochemistry, July 1, 2007; 65(1): 187 - 212. [Full Text] [PDF]

				S. Arnorsson, A. Stefansson, and J. O. Bjarnason Fluid-Fluid Interactions in Geothermal Systems Reviews in Mineralogy and Geochemistry, July 1, 2007; 65(1): 259 - 312. [Full Text] [PDF]

				J. D. Webster and C. W. Mandeville Fluid Immiscibility in Volcanic Environments Reviews in Mineralogy and Geochemistry, July 1, 2007; 65(1): 313 - 362. [Full Text] [PDF]

				W. Heinrich Fluid Immiscibility in Metamorphic Rocks Reviews in Mineralogy and Geochemistry, July 1, 2007; 65(1): 389 - 430. [Full Text] [PDF]