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Anatexis in the Hercynian basement of NE Sardinia, Italy: a case study of the migmatite of Porto Ottiolu
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P-T conditions in calc-silicate nodules from the metamorphic basement of NE Sardinia,Italy
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Pectolite in calc-silicates from NE Sardinia, Italy: evidence of metasomatism during Variscan metamorphism
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Transformation of cumulate mafic rocks to granulite and re-equilibration in amphibolite and greenschist facies in NE Sardinia, Italy
No full textThe ultramafic amphibolites hosted in the Hercynian migmatite of NE Sardinia consist of three main compositional layers
(A, B, C) from a few metres to a few decametres thick. Layer A is made up of coarse-grained olivine, chlorite, amphibole,
spinel, minor pyroxene, garnet and, rarely, plagioclase. Layer B is made up of coarse-grained plagioclase, olivine, pyroxene,
spinel, garnet and amphibole. Layer C consists mainly of porphyroblastic garnet, pyroxene, large amphibole grains (up to 5 cm)
and minor plagioclase. On the basis of mineral assemblages and microstructures, three stages of mineralogical re-equilibration
can be recognised: granulite, amphibolite and greenschist. Primary igneous olivine and anorthite reacted under granulite
conditions to produce coronas consisting of orthopyroxene, clinopyroxene, green spinel and garnet. The amphibolite stage is
characterised by the formation of brown and green clinoamphiboles (between pyroxene and corona garnet), anthophyllite, talc,
Mg-rich chlorite, plagioclase and Cr-bearing spinel. Greenschist stage minerals, mostly replacing the mafic minerals, consist of
tremolite, fayalite, epidote, albite, calcite, dolomite and serpentine. The history of the ultramafic amphibolites started with
igneous crystallisation and continued through granulite (T = 700–740 jC, P=f8–10 kbar), amphibolite (T = 580–640 jC,
P= 4–6 kbar) and greenschist facies (T =f330–400 jC, P < 2–3 kbar). Evaluation of P–T conditions indicated a P–T path
from the protolith to granulite stage, characterised by an increase in pressure and temperature, and then from the granulite facies
through amphibolite to the greenschist stage, characterised by a decrease in pressure and temperature. The petrological
evolution of the ultramafic amphibolites and the P–T time path is discussed in the context of the Hercynian orogeny in Sardinia
Provenance, petrographical and physical characters of the volcanites used for constructing the S. Antioco of Bisarcio basilica (NE Sardinia, Italy)
No full textThe Permian Guardia Pisano (Sulcis, SW Sardinia) succession: relationships between geochemistry, mineralogy and depositional environments
No full textThe competitive effect of major anions on arsenic desorption from ferrihydrite-bearing environmental materials
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