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Relationships between foredeep deposits and hercynian nappe building in southeastern Sardinia (Italy)
No full textOrigin and evolution of the Permian - Carboniferous basin of Mulargia Lake (south - Central Sardinia, Italy) related to the Late Hrcynian extensional tectonics
No full textOn the basis of several pieces of stratigraphical and structural evidence, the origin and evolution of the Permian-Carboniferous continental basin cropping out in the Lake Nulargia area, in the nappe zone of South-Central Sardinia, are strictly related to extensional post-collisional Hercynian tectonics. Particularly, the basin developed in correspondence with the southeastern periclinal termination of the Monte Grighini metamorphic "core-complex', where active normal faults controlled the sedimentary processes, as well as the diagenetic evolution of the Permian-Carboniferous molassic deposits
Multi-stage metamorphic re-equilibration in eclogitic rocks from the Hercynian basement of NE Sardinia (Italy)
No full textEclogitic rocks are hosted within gneisses and migmatites of the Hercynian basement of NE Sardinia. They are characterized by two compositional layers: garnet-pyroxene rich-layers and amphibole-plagioclase layers. The former contain structural, mineralogical and compositional relies of eclogite facies re-equilibration. Four stages of evolution have been identified: an eclogite stage, a granulite stage and a retrograde amphibolite to greenschist stage. A possible pre(?)-eclogite stage is documented by inclusions of euhedral tschermakitic amphibole + zoisite within the core of garnet. This early stage was followed by an increase in pressure under which the eclogite climax developed (T up to 700 degrees C, P = 13-15 kbar), as documented by omphacite inclusions towards the rim of garnet.
Characteristic mineral reactions after the eclogitic stage are: omphacite --> diopside + plagioclase (symplectite) and garnet --> orthopyroxene + plagioclase. These reactions testify the presence of a granulite stage during which the peak of metamorphism was reached (T up to 870 degrees C, P approximate to 10 kbar). The orthopyroxene --> cummingtonite + quartz and garnet + diopside --> hornblende + plagioclase (kelyphite) transformations indicate extensive amphibolite retrogression (T=550-650 degrees C, P = 3-7 kbar). Finally, actinolite and chlorite developed (greenschist stage) at falling temperature and pressure (T = 300-400 degrees C, P < 2-3 kbar)
Origin and evolution of the Permian-Carboniferous basin of Mulargia Lake (south-central Sardinia, Italy) related to the late-Hercynian extensional tectonics
No full textQuartz and fluorite mineralization in the geological and structural frame of Monte Grighini (central-western Sardinia)
No full textDiscontinous metamorphic zonation in the Paleozoic units of the Hercynian chain of Sardinia, Italy
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FROM THICKENING TO EXTENSION IN THE VARISCAN BELT. KINEMATIC EVICENCES FROM SARDINIA (ITALY)
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