Tracing fossil and present day fluids in rocks: Application of the nuclear microprobe
Abstract
Geological fluids contain water, chlorides and Na as major components, and metals, CO 2 gas and CH 4 gas as minor or major components. Quantitative analysis of geological fluids in fluid inclusions and hydrothermal minerals is vital to the characterization of fluid-rock interactions. The presence and quantity of trace and minor elements can be determined in fluid inclusions and minerals by Proton-induced-X-ray-emission (PIXE) and Proton-induced-gamma-ray-emission (PIGE) with EDS analysis, based on computer-aided interpretation of X-ray spectra. A feature of the PIXE-PIGE method is the long range (deep penetration) of protons in light matrices, which allows near-surface inclusions to be analysed. The applications presented here concern samples from submarine hydrothermal deposits (Red Sea, Lau Basin), and from skarns in Central Morocco. In submarine hydrothermal processes, PIXE data show trace-element-bearing-mineral(s) in assemblages with bulk geochemical anomalies, e.g. Co- and Pb-contents in the 1000 ppm range in chalcopyrite from the Hine-Hina field, Lau basin. PIXE data for high T chimneys of the Atlantis II deep record trace element perturbations due to boiling. Hypersaline magmatic fluids in the Sn-skarns of El Hammam contain more than 1000 ppm Cu and Pb but no Zn. A Sn-borate, nordenskiöldine, has been identified in the high T-skarns, trapping a Li-bearing concentrated brine.
- Publication:
-
Nuclear Instruments and Methods in Physics Research B
- Pub Date:
- July 1997
- DOI:
- 10.1016/S0168-583X(97)00266-8
- Bibcode:
- 1997NIMPB.130..692V