As demonstrated by the chapters in this short course, stable isotope techniques are an important tool in almost every branch of the earth sciences. Central to many of these applications is a quantitative understanding of equilibrium isotope partitioning between substances. Indeed, it was Harold Urey’s (1947) thermodynamically based estimate of the temperature-dependence of 18O/16O fractionation between calcium carbonate and water, and a recognition of how this information might be used to determine the temperatures of ancient oceans, that launched the science of stable isotope geochemistry. The approach pioneered by Urey has since been used to estimate temperatures for a wide range of geological processes (e.g. Emiliani 1955; Anderson et al. 1971; Clayton 1986; Valley, this volume). In addition to their geothermometric applications, equilibrium fractionation data are also important in the study of fluid-rock interactions, including those associated with diagenetic, hydrothermal, and metamorphic processes (Baumgartner and Valley, this volume; Shanks, this volume). Finally, a knowledge of equilibrium fractionation is a necessary first step in evaluating isotopic disequilibrium, a widespread phenomenon that is increasingly being used to study temporal relationships in geological systems (Cole and Chakraborty, this volume).

In the fifty-four years since the publication of Urey’s paper, equilibrium fractionation data have been reported for many minerals and fluids of geological interest. These data were derived from: (1) theoretical calculations following the methods developed by Urey (1947) and Bigeleisen and Mayer (1947); (2) direct laboratory experiments; (3) semi-empirical bond-strength models; and (4) measurement of fractionations in natural samples. Each of these methods has its advantages and disadvantages. However, the availability of a variety of methods for calibrating fractionation factors has led to a plethora of calibrations, not all of which are in agreement. In this chapter, we evaluate the major methods for determining fractionation factors. …

Equilibrium Oxygen, Hydrogen and Carbon Isotope Fractionation Factors Applicable to Geologic Systems

http://labs.cas.usf.edu/geodesy/articles/2004/Lateral%20Variation%20in%20upper%20mantel.pdf

Lateral variation in upper mantle viscosity: role of water

Hydrogen isotope systematics of submarine basalts

Alteration of oceanic crust and geologic cycling of chlorine and water

Rapakivi granites, recently redefined as A-type granites showing rapakivi texture at least in the larger batholiths, occur on all continents and presumably represent the most voluminous continental silicic intraplate magmatism on Earth. Most of the rapakivi granites are Proterozoic (mainly 1.0 to 1.7 Ga) but also Archean (2.8 Ga) and Phanerozoic (0.05 to 0.4 Ga) are known. The magmatic association is bimodal comprising anorthosite to gabbro, diabase, minor Fe-enriched intermediate rocks, and monzonite, beside granite; mingling of silicic and mafic magmas is typical. Geochemically and otherwise, rapakivi granites show the characteristics of the Phanerozoic A-type granites, except that they encompass relatively few peralkaline rocks and that they may occur as very large (up to 40,000 km2) batholiths. Some of the rapakivi granite complexes host important Sn-polymetallic and Fe-Cu deposits. The rapakivi granites crystallized from relatively hot, restite-poor magmas at low (epizonal-subvolcanic) pressure,
 
$$a_{H_2 O} $$

 , and
 
$$a_{O_2 } $$

 . Mineral assemblages are indicative of a multiphase crystallization history; the conspicuous mantling of the perthite ovoids with plagioclase can be explained by changes in magma composition and/or, P, T, and
 
$$a_{H_2 O} $$

 affecting the stabilities of feldspars. The isotopic composition of rapakivi granites is generally compatible with a lower crustal protolith. The latter could have been either a melt-depleted residue or otherwise relatively anhydrous igneous or metaigneous rock. Melting of the protolith commenced under vapor-absent conditions and was induced by heat from the contemporaneous mantle-derived mafic magmas. The widespread rapakivi granite magmatism in the Middle Proterozoic may have been related to the establishment of a major continental mass (supercontinent).

One hundred years of rapakivi granite

D/H ratios of phlogopites and amphiboles from rocks of possible mantle origin and also those of water from (glass?) inclusions in olivines of the olivine nodule and peridotites have been determined. The mantle water seems to have aδD value of —85±10‰ on the basis of results of inclusions in the nodule-olivine.

Hydrogen isotope composition of deep-seated water

Quartz, K-feldspar, albite and anorthite were equilibrated with water vapor in Pt capsules at 20kb and in the temperature range from 800 to 1, 300°C. The water in the capsules during the high temperature and pressure run seems to exist in two states, aqueous fluid and dissolved water (structural water) in the melt. In the process of extracting these waters, four kinds of water were distinguished experimentally: 1) Water extracted by puncturing the capsule in vacuum, 2) Water released from bubbles in quenched products, i.e., glasses, during grinding in an agate mortar, 3) Water extracted from pulverized product in evacuation process at room temperature, and 4) Water extracted in vacuum at high temperature. D/H ratios of waters of 1), 3) and 4) were measured. Taking water 4) to be dissolved water in melt, the fractionation factors between this and other waters from aqueous fluid were estimated. Deuterium is enriched in the dissolved water for albite and K-feldspar melts, D/H is almost the same for the aqueous fluid and dissolved water in the anorthite melt, and deuterium is much depleted in the dissolved water in the quartz melt.

D/H fractionation between water and the melts of quartz, K-feldspar, albite and anorthite at high temperature and pressure

The water content and D/H ratio of pairs of phlogopite and richterite in kimberlite samples were measured. The water contents of both minerals were lower than the formula content. On the basis of D/H ratios of the pair, phlogopite and richterite can not be regarded as a simple equilibrium product with respect to hydrogen isotope exchange. It seems impossible to estimate D/H ratio of the mantle water through D/H ratios of the hydrous silicate pairs.

D/H ratios of the coexisting phlogopite and richterite from mica nodules and a peridotite in South African kimberlites

Chemistry dependence of δD of chlorites is inferred from data for natural chlorites. δD of water equilibrated with those chlorites is estimated to be −2∼−8‰.

A preliminary study of D/H ratios of chlorites

Several specimens of coexisting biotite and hornblende were separated from the rapakivi granites, Svecofennian and Karelian granitic rocks of Finland and subjected to D/H ratio measurements and chemical analyses. D/H distribution between biotite and hornblende in the rapakivi and Svecofennian granitic rocks showed the disequilibrium situation defined by KURODA et al. (1977a). The origin of equilibrium and disequilibrium granites was discussed on the basis of the content and state of water in magmas.

Tetsuro Suzuoki

Papers

Hydrogen isotope composition of deep-seated water

D/H fractionation between water and the melts of quartz, K-feldspar, albite and anorthite at high temperature and pressure

D/H ratios of the coexisting phlogopite and richterite from mica nodules and a peridotite in South African kimberlites

A preliminary study of D/H ratios of chlorites

Hydrogen isotope study on biotite and hornblende from finnish granitic rocks.