O, H, C isotope study of rocks from the KTB pilot hole: crustal profile and constraints on fluid evolution

Article Abstract:

A study of stable isotopes reveals the degree of rock-water interaction, the details of the fluid's primary isotopic composition, the isotope chemistry of fluid evolution during the process of uplift and cooling and the stable isotopic composition of a particular crustal profile. The study was based on the pilot hole of the continental deep borehole (KTB) in Bavarian Oberpfalz, in the western Bohemian Massif. The bore hole exhibits little proof of water-rock reactions and varied values of whole-rock oxygen isotope lithologies. Examples of modern fluids with isotopic composition reveal that continuous evolution of fluid takes place in a closed system during regression.

Composition, Fluids

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A detailed Th, Sr and O isotope study of Hekla: differentiation processes inan Icelandic volcano

Article Abstract:

An analysis of isotope ratiosfrom samples found in the Hekla volcano is presented. Th, Sr and O isotopes were analyzed from the volcano's prehistoric and historic eruptions. Basaltic andesite and rhyolite were found to be dominant in their composition. It is shown that the 230Th/232Th and Th/U ratios best functioned as tracers of magmatism. In addition, fractional crystallization was observed as the volcano's main differentiation process.

Natural history, Iceland

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Phase relations in the MgO-P2O5-H2O system and the stability of phosphoellenbergerite: petrological implications

Article Abstract:

A study of the phase relations of the phosphate end-member in the MgO-P2O5-H2O system was conducted to examine the stability of pure phosphoellenbergerite. It was found that the system included the phases of Mg2PO4OH polymorphs, holtedahlite, althausiste, Mg3(PO4)2 polymorphs, farringtonite and phosphoellenbergerite. The latter, although a high-pressure phase, is stable to much lower pressures and higher temperatures.

Minerals (Geology), Rocks, Rock-forming minerals, Phosphate minerals

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