Preservation of wines

Abstract

Endogreisen and exogreisen weakly mineralized with Bi, Sn, and Mo are associated with two of three granite porphyry (granite) cupolas hosted in Silurian metasedimentary rocks at True Hill, southwestern New Brunswick. The epizonal, weakly peraluminous and compositionally evolved True Hill granite is quartz and K-feldspar porphyritic; groundmass textures, such as granophyric patches, miarolitic cavities, and pegmatite pods, are indicative of rapid cooling and vapor saturation.The greisen mineralization in cupolas B and C is overprinted by various types of alteration, reflecting multi-stage devolatilization of the magma. The most intense topaz-bearing greisen is confined mainly to the apical parts of the granite. In places, fluorite is associated with silicification, sericitization, and chloritization, which is common to greisen-type alteration. The alteration types reflect the physical and chemical changes in the hydrothermal fluid that was derived principally by second boiling of the magma. Al-normalized, mass-balanced geochemical data supported by petrographic observations show that in the greisenized True Hill granite, Fe, Mn and Mg enrichment corresponds to chlorite and/or Fe-muscovite alteration and are coincident with leaching of Na and K and deposition of SiO2. Ca was remobilized in the greisen environment, but erratically deposited as fluorite. Minor P and LREE enrichment are reflected by the presence of monazite in the greisen. The HFSE are mobile to a minor degree, based on correlations with elements known to be hydrothermally mobile. The base metals correlate with S and other ore-forming elements. The distribution of many of the trace elements is related to alteration, including the leaching of alkalis, which leads to the stabilization of aluminosilicates, principally muscovite and topaz. The distribution of trace elements reflects their relative mobility during greisenization, with high-field-strength elements (Zr and Ti) the most immobile and the lithophile and chalcophile elements the most mobile. Breccias and greisen alteration in cupola C at True Hill are similar to those at the base of the W-Mo-Bi porphyry-greisen in the Fire Tower zone above the Mount Pleasant fine-grained granite.