O-H_Stable_Isotopes

Solid melt or anhydrous solid hydrous solid reactions

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Unformatted text preview: ≈ A/T2 + B and for most minerals containing OH groups, lnα ≈ A/T + B (or lnα ≈ A /T2 + B/T + C) • • • for most solid-solid reactions, B = 0 for most solid-fluid, solid-melt, or anhydrous solid-hydrous solid reactions, B ≠ 0 Key is that fractionation of species is generally temperature dependent. ΔA-B = δA – δB ≈ 1000 lnαA-B = A/T2 + B/T + C Wednesday, 15 August, 12 Qtz-Magnetite Fractionation 80 DXqtz-mag 60 40 20 0 250 350 450 550 650 750 850 950 1050 T(oK) Wednesday, 15 August, 12 O and H Stable Isotopes • Used primarily to trace fluids and solvent origins in hydrothermal fluids. • Can obtain O and H data from minerals with O or OH groups in their structure (micas, hornblende, quartz, kfsp, etc.); directly from water. • Good for documenting fluid-rock (water:rock) interaction and picking out “hot zones” in hydrothermal systems. • Fractionation of O and H can be obtained by: • • • Wednesday, 15 August, 12 Evaporation and transpiration Water:rock interaction Mineral:water reaction O Isotope Composition of Earth Materials From Rollinson (1993) Wednesday, 15 August, 12 H Isotope Composition of Earth Materials From Rollinson (1993) Wednesday, 15 August, 12 Isotopic Fractionation and Geothermometry ΔA-B = δA – δB ≈ 1000 lnαA-B • • Gives true T of mineralization (or alteration). Requirements: • well-calibrated, strongly T-dependent fractionation factors • species that were in isotopic equilibrium a...
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This document was uploaded on 03/06/2014 for the course ES 4502 at Memorial University.

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