Magmatic Apatite

Microlithofacial classification of the sandstones is based on Dott s classification modified by Pettijohn et al. (1972). They are mostly arenites and subarkose and quartz wackes (rare sublithic, sporadically lithic and arkosic). Quartz is the main component of the sandstones (about 60-70 vol. percent). Feldspars (6 vol. percent) are mostly represented by potassium feldspars with plagioclases in lesser amounts. Some micas (muscovite and biotite) and chlorites are observed. Mica content of arenites reaches 3 vol. %, but is higher in the wackes. Heavy minerals present include zircon, sphene, rutile and apatite. Magmatic rocks (volcanic more than Plutonic) are predominant among lithoclasts (about 2 vol. %), but some metamorphic and sedimentary clasts being present too. 

Later (Zotov 1980, 1989 Korzhinskii et at. 1984 Marakushev et at. from 2002 up to 2006), it was shown that transmagmatic fluids are able to transport ore metals whose portion may be predominant in endogenic deposits as for example in R-Pd-Cu-Ni sulfide deposits (same ref.), apatite deposits of alkali (Zotov 1989) and alkali-carbonatite (Seredkin et at. 2004) magmatic massifs. This concept is essentially useful as an application for understanding of genesis of big endogenic ore deposits (Zotov 1980). 

Sedimentary carbonate-fluor-apatite Cas(P04,003)3 is not luminescent under X-rays, and under UV lamp excitation it is characterized by broad structureless bands which are very similar to those encountered in many sedimentary minerals. It was concluded that this luminescence is due to different kinds of water-organic complexes (Tarashchan 1978). For this reason the luminescence properties of the sedimentary apatites is much less informative compared to magmatic apatite and attracted not much attention. 

It is interesting to note that in magmatic apatites the luminescence of uranium containing centers have not been discovered before or after oxidizing heating. Thus it is reasonable to suppose that uranium is present mainly in the 11" + form. The U with an ionic radius of 0.97 A may be located in the apatite structure instead of Ca with the ionic radius of 0.99 A. The most likely way for achieving the excess charge compensation is the Na" for Ca " structural substitutions. 

Relatively recently, AIS Sommer GmbH of Germany delivered a laser-induced fluorescence (LIP) analyzer for quality control in minerals and mineral processing (Broicher 2000). The LIP analyzer includes two light detector systems with three photomultipliers each, which evaluate three spectral bands in two time windows each. It was done in the Kiruna phosphorous iron ore mine, Sweden. The limitation of LIP analysis is that its accuracy depends on the complexity of the composition of the ore and the concentration and fluorescence properties of the critical minerals in relation to all the other minerals present. The phosphorous iron ore in Kiruna is ideal for LIP analyzes, because its iron minerals are practically non-luminescent, while magmatic apatite is strongly fluorescent with intensive emissions of Ce and Eu ". ... 

The study of the basaltic dykes in evaporites demonstrates that dissolution and precipitation of phosphate minerals is a key process for the control of REE mobility and REE fractionation. In the present case, all REE found in secondary apatite in the basalt and in the salt are derived from the dissolution of primary magmatic apatite during basalt corrosion. This loss of REE from the basalt to the salt was not sufficient to lower significantly the REE concentrations of the basalt and it could only be detected by the analysis of the salt. The absolute quantity of REE transferred from the basalt into the salt, however, cannot be quantified because we have no three-dimensional control on the REE concentrations around the basalt apophy sis. 

In some works (Parak, 1975) even the apatite-iron ores of Kiruna in Sweden, which are believed to be intrusive-magmatic, are attributed to exhalative-sedimentary deposits. 

The presence of volatile-bearing phases such as phlogopite, apatite, and carbonates in kimberhtes testify to the volatile-rich nature of the parental magma (e.g., Mitchell, 1986). The ubiquitous serpentization present in kimberlites cannot be used as evidence of magmatic water, with the exception of groundmass serpentine that is interpreted to be primary in nature. As discussed by Mitchell (1986), there are hmited stable isotopic data consistent with a meteoric origin for some of the water in the serpentine. However, it is unclear if these results could be attributed to postemplacement exchange of deuteric serpentine with meteoric fluids. 

Corfu F. and Stone D. (1998) The significance of titaniite and apatite U—Pb ages constraints for the post-magmatic thermal-hydrothermal evolution of a bathoUthic complex. 

Sedimentary phosphate ores, such as those found in Florida and Morocco, tend to have high concentrations of uranium, whereas the opposite occurs with magmatic ores, such as apatite from Kola. Typical activity concentrations of U are 1500 Bq kg in sedimentary phosphate deposits and 70 Bq kg in apatite. U is generally found in radioactive equilibrium with its decay products. The activity concentrations of Th... 

Sedimentary apatite deposits are in quantity much more important than the magmatic ones. 

The D/H values of magmatic, hydrous minerals apatite, Ti-rich amphibole, and biotite have been analyzed in five martian meteorites by ion microprobe (Leshin 2000 Rubin et al. 2000 Watson et al. 1994). The elevated and variable D/H values of water discovered in the minerals (5D +800 to +4300) are interpreted qualitatively as representing a mixture of magmatic water in the minerals with a D-enriched component derived from the martian atmosphere (with a D/H value 5 times terrestrial), through isotopic exchange with D-enriched groundwaters introduced after the phases crystallized. 

Figure 13. D/H and water contents of apatite grains from martian meteorite QUE94201 after Leshin (2000). The data are interpreted to represent a mixture of two end members, and most plausibly represent addition (or exchange) of water with an atmospheric D/H signature (5D +4000 %o) to minerals which initially uniformly contained water with 5D of 90ftt250 %o, or approximately twice the D/H value cotmnonly assumed for magmatic water on Mars. The curve shows the mixing model from which the initial D/H of the minerals was calculated.

Hughes JM, Cameron M, Crowley KD (1990) Crystal stractures of natural ternary apatites Solid solution in the Cas(P04)3X (X= F, OH, Cl) system. Am Mineral 75 295-304 Kay Ml, Young RA, Posner AS (1964) Crystal stracture of hydroxylapatite. Nature 204 1050-1052 Kovalenko VI, Antipin VS, Vladykin NV, Smirnova YV, Balashov YA (1982) Rare-earth distribution coefficients in apatite and behavior in magmatic processes. Geochem Inti 19 174-183 Mackie PE, Young RA (1974) Fluorine-chlorine interaction in fluor-chlorapatite. J Solid State Chem 11 319-329... 

A strong temperature dependence on apatite/melt exchange equilibria has been recognized for some time, necessitating the determination of the temperature at which apatite crystallizes when making estimates of magmatic halogen concentrations or... 

---