ABSTRACT Andesites are iconic of subduction zone magmatism. Yet intermediate magmas (57–66 wt % SiO2) less abundant than generally thought in arc settings. A comparison experimental hydrous liquid lines descent, melt inclusions and bulk-rock compositions demonstrates the importance polybaric crystallization–differentiation producing compositional range dictating relative abundance melts, but al...

The Gacun deposit is a typical Volcanic Hosted Massive Sulfide (VHMS) associated with Late Triassic seafloor calc-alkaline felsic volcanics. Studies of zircon ages, petrology, major and trace element geochemistry, Sr-Nd-Hf isotope geochemistry volcanic rocks from the Northern Yidun arc were undertaken in this paper. We reshaped magmatic system activity time, defined origin magma evolution, prop...

introduction agates are presumed as a kind of precious stone that could be formed in magmatic, metamorphic and even sedimentary environment. mechanism for agate formation is not clear and is produced in laboratories. some hot springs and geothermal activity or white chimneys in the ocean floor, have some deposits like chalcedony but never produce agate. agate formation temperature varies betwee...

In the Central Andes, large (> 500 km2) and long-lived (1–5 Ma) volcanic clusters (LVCs) are less explored their eruptive history magmatic regimes understood than smaller, short-lived (<0.5 Ma), individual stratocones. The Chachani-large cluster (C-LVC) sizeable volume (c. 290 km3) consists of twelve edifices forming 1.06–0.64 Ma group stratovolcanoes 0.46–0.05 domes coulees block-lava flow fie...

Abstract New geochemical data, including Sr–Nd–Pb isotopes for whole-rock and groundmass samples, are reported edifice-forming eruptives at Tongariro volcano, Zealand, which span its ~ 350 ka to late Holocene history. medium-K basaltic-andesites dacites (53.0–66.2 wt% SiO 2 ) that evolved via assimilation-fractional crystallisation (AFC) processes partly or mostly in the uppermost 15 km of crus...