Generation of a crust-mantle magma mixture: magma sources and contamination at Cerro Panizos, central Andes

Article Abstract:

Equal amounts of late Miocene mantle-derived basalts and melts from the lower crust combined to form the Cerro Panizos magmas in the central Andes. Two large dacitic ignimbrites and many andesitic and dacitic lava flows and domes originated from the magma eruptions of the Cerro Panizos caldera. The upper and middle crustal rocks moved down due to crustal thickening below the central Andes. Constant Pb isotopic values and high Pb contents suggest that the Pb came from the crust and was unaffected by crustal contamination.

Andes, Earth, Crust (Geology)

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Primary Ca-rich carbonatite magma and carbonate-silicate-sulphide liquid immiscibility in the upper mantle

Article Abstract:

An analysis of a nodule's textural relations, from Montana Clara of the Canary islands, reveals a new harzburgite and lava interaction. The presence of liquid immiscibility is among calciocarbonatite, sulphide and silicate melts in the upper mantle peridotite nodule. Wehrlitic alteration zones contain the carbonates, which are linked to a second generation of minerals, such as olivine, clinopyroxene and spinel. Globules are formed in silicate glass by calciocarbonatite and sulphide phases.

Research, Observations, Mixing, Mixing (Materials processing), Analytic geochemistry

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Reactions between mantle xenoliths and host magma beneath La Palma (Canary Islands): constraints on magma ascent rates and crustal reservoirs

Article Abstract:

Spinel-bearing perioditic mantle xenoliths from the 1949 eruption on La Palma were modified mineralogically and chemically during prolonged reaction with their host magma. The magmatism that brought the peridotites to the surface caused two distinct generations of xenolith fractures. Findings showed proof of prolonged storage of the xenoliths in the crust, constraining a multistage magma ascent.

Rocks, Igneous, Xenoliths

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