Evolution of young andesitic–dacitic magmatic systems beneath Dominica, Lesser Antilles

摘要: The geology of Dominica, Lesser Antilles, is dominated by young (< 200 ka) andesitic–dacitic volcanic deposits. Although previous studies have mostly focused on the Plat Pays Volcanic Centre (PPVC), a complex located south-western tip evolved deposits are found across entire island. Dominica's rocks characterized wide ranges in mineral compositions and host disequilibrium features. Mineral–mineral mineral–melt equilibrium constraints suggest that three separate assemblages associated with development these magmas. While Rayleigh fractionation modeling indicates groups may be related via fractional crystallization, enclaves irregular boundaries chilled margins provide evidence open-system processes such as magma mingling. To explain textures, we propose Dominica andesites dacites result convective self-mixing within reservoirs comprised distinct components: 1) underplating basalt, 2) basaltic–andesitic mush 3) interstitial rhyolitic melt. A notable exception Aux Diables, northernmost center island, which has strikingly different whole-rock geochemistry than other centers. Trace element this influenced lower crustal assimilation addition to crystallization. This study suggests necessary component generation magmas beneath island Dominica. Available ages existed parts for at least ka.