GEOCHEMICAL COMPARISON OF THE SUBVOLCANIC APPINITE SUITE OF THE BRITISH CALEDONIDES AND THE DURBACHITE SUITE OF THE CENTRAL-EUROPEAN HERCYNIDES - EVIDENCE FOR ASSOCIATED SHOSHONITIC AND GRANITIC MAGMATISM

Subvolcanic ite-hornblendite-kentallenite-diorite-granodiorite masses of the appinite suite that are spatially and temporally associated wit h the much more voluminous granitic plutons of the British Caledonides have major element proportions and REE patterns indicative of shoshon itic affinities. Hornblendite-monzonite-syenogabbro -pyroxene melasyen ite-durbachite-biotite-rich syenite-biotite-rich granite masses of the plutonic durbachite suite of the Bohemian Massif of the Central Europ ean Hercynides, that also are spatially and temporally associated with much more voluminous granitic plutons, have geochemical characteristi cs that generally correspond with those of the appinite suite. Composi tionally both suites resemble lamprophyres emplaced during the latter parts of the respective episodes. Both the appinite and durbachite sui tes show independence of K/Rb and SiO2 with the two suites having main ly different but somewhat overlapping K/Rb ratios. Other geochemical c haracters, as shown by fields and trends on K vs Rb, AFM and other plo ts, point to the durbachite suite representing generally more evolved products of shoshonitic magma than members of the appinite suite. Howe ver, there are different geochemical characteristics, including higher Cr/Ni ratios in the durbachite suite and Co present in lower proporti ons in the appinite suite. These differences are the result of differe nt histories of freezing, remelting and partial separation and remixin g of fractionation products and reflect the explosive subvolcanic vs p lutonic regimes of the appinitic and durbachitic suites, respectively. Support for this petrogenesis is provided by mineral compositions and comparison of compositions of mineral phases and the rocks in which t hey occur.