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New major and trace element data, and Sr-Nd-Pb-O isotopic ratios for volcanic mafic rocks outcropping at Monti Ernici in the Mid Latina Valley (southern Latium) are reported, with the aim of investigating the nature and evolution of Plio-Quaternary K-rich volcanism in Central Italy. Petrographical and geochemical studies allow us to identify mafic rocks ranging from ultrapotassic (HKS) to shoshonitic (SHO), and calc-alkaline (CA), these last ones being identified for the first time. The CA rocks exhibit the most primitive signatures for Sr, Nd, and Pb isotopes (87Sr/86Sr =0.706326-0.706654; 143Nd/144Nd = 0.512388- 0.512361; 206Pb/204Pb = 18.944-18.940). The ?18O values are variable (?18Ocpx from + 5.75 to + 7.08 ?; and ?18Ool from + 5.50 to +6.23 ?), suggesting interaction with carbonate wall rocks. Radiogenic isotope ratios and incompatible elements distribution have several characteristic in common with equivalent rocks from Pontine Islands (Ventotene), Campania and Aeolian arc volcanoes. Conversely, the HKS rocks closely resemble the ultrapotassic rocks from the Roman Province (87Sr/86Sr = 0.709679-0.711102; ?18Ocpx from + 6.27 to + 7.08 ?). The high ratios of LILE (Large Ion Lithophile Elements: Rb, Cs, Th, U, K, LREE) and HFSE (High Field Strength Elements: Ta, Nb, Zr, Hf, Ti), and radiogenic isotope compositions of CA to HKS rocks indicate that all suites contain subduction-related components, and suggest a N-MORB-type mantle source variably contaminated by hydrous fluids and/or melts released by undergoing slabs, possibly during two distinct stages of metasomatism. The coexistence of ultra-alkaline and sub-alkaline orogenic magmatism, combined with tectonic, geophysical and geological evidence, support the possibility that the mantle beneath central-southern Italy (Ernici-Roccamonfina Province) was vertically zoned and produced different magma suites during time.

New major and trace element data, and Sr-Nd-Pb-O isotopic ratios for volcanic mafic rocks outcropping at Monti Ernici in the Mid Latina Valley (southern Latium) are reported, with the aim of investigating the nature and evolution of Plio-Quaternary K-rich volcanism in Central Italy. Petrographical and geochemical studies allow us to identify mafic rocks ranging from ultrapotassic (HKS) to shoshonitic (SHO), and cale-alkaline (CA), these last ones being identified for the first time. The CA rocks exhibit the most primitive signatures for Sr, Nd, and Pb isotopes (Sr-87/Sr-86 = 0.706326-0.706654; Nd-143/Nd-144 = 0.5 12388-0.512361; Pb-206/Pb-204 = 18.944-18.940). The delta O-18 values are variable delta O-18(cpx) from +5.75 to +7.08 parts per thousand; and delta O-18(ol) from +5.50 to +6.23 parts per thousand), suggesting interaction with carbonate wall rocks. Radiogenic isotope ratios and incompatible elements distribution have several characteristic in common with equivalent rocks from Pontine Islands (Ventotene), Campania and Aeolian arc volcanoes. Conversely, the HKS rocks closely resemble the ultrapotassic rocks from the Roman Province (Sr-87/Sr-86 = 0.709679-0.711102; delta O-18(cpx) from +6.27 to +7.08 parts per thousand). The high ratios of LILE (Large Ion Lithophile Elements: Rb, Cs, Th, U, K, LREE) and HFSE (High Field Strength Elements: Ta, Nb, Zr, Hf, Ti), and radiogenic isotope compositions of CA to HKS rocks indicate that all suites contain subduction-related components, and suggest a N-MORB-type mantle source variably contaminated by hydrous fluids and/or melts released by undergoing slabs, possibly during two distinct stages of metasomatism. The coexistence of ultra-alkaline and sub-alkaline orogenic magmatism, combined with tectonic, geophysical and geological evidence, support the possibility that the mantle beneath central-southern Italy (Ernici-Roccamonfina Province) was vertically zoned and produced different magma suites during time

Fine-grained peraluminous synkinematic leuco-monzogranites (SKG), of Cambro-Ordovician age, occur as veins and sills (up to 20-30 m thick) in the Deep Freeze Range, within the medium to high-grade metamorphics of the Wilson Terrane. Secondary fibrolite + graphite intergrowths occur in feldspars and subordinately in quartz. Four main solid and fluid inclusion populations are observed: primary mixed CO2 + H2O inclusions + Al2SiO5 +/- brines in garnet (type 1) ; early CO2-rich inclusions (+/- brines) in quartz (type 2) ; early CO2 + CH4 (up to 4 mol%) +/- H2O inclusions + graphite + fibrolite in quartz (type 3); late CH4 + CO2 + N2 inclusions and H2O inclusions in quartz (type 4). Densities of type 1 inclusions are consistent with the crystallization conditions of SKG (almost-equal-to 750-degrees-C and 3 kbar). The other types are post-magmatic: densities of type 2 and 3 inclusions suggest isobaric cooling at high temperature (almost-equal-to 700 -550-degrees-C). Type 4 inclusions were trapped below 500-degrees-C. The SKG crystallized from a magma that was at some stage vapour-saturated; fluids were CO2-rich, possibly with immiscible brines. CO2-rich fluids (+/- brines) characterize the transition from magmatic to post-magmatic stages; progressive isobaric cooling (T< 670-degrees-C) led to a continuous decrease of f(O2), entering in the graphite stability field; at the same time, the feldspars reacted with CO2-rich fluids to give secondary fibrolite + graphite. Decrease of T and f(O2) can explain the progressive variation in the fluid composition from CO2-rich to CH4 and water dominated in a closed system (in situ evolution). The presence of N2 the late stages indicates interaction with external metamorphic fluids.

A study of brittle deformation within a segment of the Hercynian intrusive complex of Gallura (comprising porphyritic biolite monzogranitic and granodioritic intrusions) reveals a quite regular network of fluid inclusion planes (interpreted as healed paleocracks) and open microcracks. Fluid inclusion planes and microcracks in 9 oriented samples show a consistent orientation across different intrusions; two principal, almost orthogonal sets have been recognized: N20-60-degrees-E-trending and N100-120-degrees-E-trending directions; both mainly consist of subvertical planes. A subhorizontal set is nearly always present as healed microcracks; it occurs as open cracks only in one sample. Microthermometric investigations on fluid inclusions show that Na dominated aqueous fluids (salinity from 0.9 to 12.3 wt.% NaCl eq.; ThL = 111-257-degrees-C) circulated throughout the intrusive complex, along almost all the microfracture sets during the late-stage hydrothermal history. Locally, subordinate Li- or Ca-, K- and Na-bearing brines have been detected along N100-degrees-E- and N160-degrees-E-trending paleocracks. Li-bearing brines have salinities ranging from 11 to 17 wt.% LiCl eq. and ThL from 74 to 171-degrees-C; salinity in Ca-dominated brines varies from 4.9 to 21.8 wt.% NaCl eq. and ThL from 130 to 217-degrees-C. The principal set directions (N20-60-degrees-E and N100-120-degrees-E) are often shared by fluid inclusion planes and open n-microcracks: it is suggested that they belonged to the same brittle deformation episode, related to late Hercynian batholith cooling and uplift

The overall relationships between alteration assemblages, mineralization and fluid phases in the Calabona dacite-andesite porphyritic intrusive complex typify a porphyry copper system associated with low SiO 2 rocks and represent a "variation on a theme" of classic porphyry copper deposits (Gustafson and Hunt, 1975). The hydrothermal alteration assemblages define concentric patterns centered on the inner part of the intrusion. These alteration zones vary from a potassic core through a well-developed phyllic shell, a spotty argillic zone, and an outer propylitic fringe. The hypogene subeconomic copper mineralization (0.09% Cu) occurs at the boundary between the potassic and the phyllic zones,in disseminations and in veins. A shallow supergene sulfide zone (0.04% Cu) is mainly located in the argillic alteration. The well-preserved zoning of fluid inclusion populations within the alteration-mineralization pattern, and their P-T-X properties have led to the identification of a multiple-stage hydrothermal event. The earliest recorded fluid (fluid I) was a high-temperature brine characterized by significant concentration of Na, K, Ca, Cu, Fe, and S. This fluid formed the potassic assemblage and possibly represents the transporting agent for the copper. An important boiling episode of the fluid phase (fluid II) occurred probably as a result of a drop in pressure and was responsible for the evolution from potassic to phyllic alteration and for the main stage ( hypogene) of copper deposition. The latest stage (fluid III) was marked by increasing and continuous cooling and dilution. Argillic alteration and deposition of the supergene mineralization occurred at this time.