Authigenic Monazite and Xenotime from Pelitic Metacherts in Pumpellyite–actinolite-facies Conditions, Sestri–voltaggio Zone, Central Liguria, Italy
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چکیده
Monazite-(Ce) and xenotime-(Y) were found in the metacherts (pumpellyite–actinolite-facies conditions: 3 ≤ P ≤ 4 kbars and 300 ≤ T ≤ 350°C) of the Monte Figogna Unit, Sestri–Voltaggio Zone, Liguria, in Italy, as scattered submillimetric grains in pelitic beds and as euhedral crystals in both millimeter-thick quartz veins and open fissures. Their composition is comparable to those of known occurrences in metapelites from greenschist-facies conditions. The textural evidence points to a synmetamorphic authigenic origin of these phases related to local mobilization and reconcentration of the REE during the metamorphic recrystallization of the clay fraction.
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