Seawater chemistry isotopic composition

The above argument on the calculation of chemical composition of ore fluids, seawater-rock interaction experiments, and isotopic compositions of ore fluids clearly demonstrates that Kuroko ore fluids were generated by seawater-rock interaction at elevated temperatures. The chemistry of present-day hydrothermal solution venting from back-arc basins and midoceanic ridges (sections 2.3 and 2.4) also support this view. 

The marine strontium isotope record is the proxy record most commonly used to constrain the geologic history of chemical weathering. However, in recent years it has been widely criticized as a proxy indicator of past silicate weathering rates. The osmium isotope record is analogous to the strontium record in many respects, and can help to constrain interpretations of the marine strontium isotope record. In this section the geochemical factors that influence the osmium and strontium isotope compositions of seawater are reviewed, and the structure of these two records of Cenozoic ocean chemistry is discussed. 

Strauss H. (2002) The isotopic composition of Precambrian sulphide—Seawater chemistry and biological evolution. In Precambrian Sedimentary Environments A Modern Approach to Ancient Depositional Systems. International Association of Sedimentologists Special Publication no. 33 (eds. W. Altermann and P. L. Corocoran). Blackwell, Oxford, pp. 67-105. 

Before isotopic compositions from fossil benthic foraminiferal specimens are used in palaeoenviron-mental reconstructions, it is important to determine whether the shell chemistry of live individuals (i.e. those stained with rose Bengal Bernhard 2000) of a particular species reflect the conditions of the surrounding seawater, i.e. does the foraminifera calcify in isotopic equilibrium with the surrounding environment ... 

Lavasseur, S., Frank, M., Hein, J.R. and Halliday, A.N., 2004. The global variation in the iron isotope composition of marine hydrogenetic ferromanganese deposits impliations for seawater chemistry Earth and Planetary Science Letters, 224 91-105. 

Wolery (1978) and Reed (1982, 1983) have indicated based on a computer calculation of the change in chemistry of aqueous solution and mineralogy during seawater-rock interactions that epidote is formed under the low water/rock ratio less than ca. 50 by mass. Humphris and Thompson (1978), Stakes and O Nell (1982) and Mottl (1983) have also suggested on the basis of their chemical and oxygen isotopic data of the altered ridge basalts that epidote is formed by seawater-basalt interaction at elevated temperatures (ca. 200-350°C) under the rock-dominated conditions. If epidote can be formed preferentially under such low water/rock ratio, the composition of epidote should be influenced by compositions of the original fresh rocks. 

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