The Temperino deposit is an historical Cu-Zn-Pb skarn located in the the Tuscan magmatic province of Italy. It consists mainly of massive lenses of sulfide bodies, enclosed within white marble, from which chalcopyrite, sphalerite, and galena were exploited in the past. These bodies occur close to trachyandesite and rhyolite porphyry dikes and within NNW-SSE trending, en-echelon and discontinuous ilvaite and hedenbergite skarn masses. A peculiar characteristics of this deposit is the presence of quartz-rich geodes wthin the ilvaite and hedenbergite skarns. The geodes occur close to the sulfide lenses, have variable volumes (range: from 10-20 cm3 to 2-3 m3), and are enclosed within the massive ilvaite and hedenbergite skarns. They represent the end of the main mineralizing event at Temperino. In addition to large euhedral quartz crystals (up to 15 cm in legth), geodes contain ilvaite, calcite, epidote, and small propostions of ore minerals. We determined the physical-chemical properties of the geode fluid combining microthermometry, Raman spectrometry, EMPA, CL imaging, and LA-ICP-MS of fluid inclusions entrapped at several stages of euhedral quartz growth. The crystals show alternations of 100 micron- to 1 mm thick bands variably enriched in Al, Na, Li, Rb, Sr, Sb, Ba, Mn, B, Cs, and Zn, so they are chemically zoned. This zoining was accounted for in the determination of inclusion compositions. Fluid inclusions host two- (L, V) to five phase (L,V, and 3 solids) aqueous fluids. Depite this, their estimated bulk salinity is unexpectedly low (0.4-2.9 wt% NaCl eq.) and does not change systematically within the crystals. The Th(total) of all fluids is consistently in the 220-260 °C range and homogenzation occurs mainly by bubble disappearance. The main inclusion components are (in order of relative abundance) Na, K, B, Sr, Sb, Ba, Mn, Rb, Cs, Zn, Pb, and Cu, i.e., the same that make the quartz zoning.
Genesis of quartz-rich geodes from peculiar aqueous fluids in a Cu-Zn-Pb skarn (Temperino mine, Italy) and relations with ore bodies
GAROFALO, PAOLO;
2013
Abstract
The Temperino deposit is an historical Cu-Zn-Pb skarn located in the the Tuscan magmatic province of Italy. It consists mainly of massive lenses of sulfide bodies, enclosed within white marble, from which chalcopyrite, sphalerite, and galena were exploited in the past. These bodies occur close to trachyandesite and rhyolite porphyry dikes and within NNW-SSE trending, en-echelon and discontinuous ilvaite and hedenbergite skarn masses. A peculiar characteristics of this deposit is the presence of quartz-rich geodes wthin the ilvaite and hedenbergite skarns. The geodes occur close to the sulfide lenses, have variable volumes (range: from 10-20 cm3 to 2-3 m3), and are enclosed within the massive ilvaite and hedenbergite skarns. They represent the end of the main mineralizing event at Temperino. In addition to large euhedral quartz crystals (up to 15 cm in legth), geodes contain ilvaite, calcite, epidote, and small propostions of ore minerals. We determined the physical-chemical properties of the geode fluid combining microthermometry, Raman spectrometry, EMPA, CL imaging, and LA-ICP-MS of fluid inclusions entrapped at several stages of euhedral quartz growth. The crystals show alternations of 100 micron- to 1 mm thick bands variably enriched in Al, Na, Li, Rb, Sr, Sb, Ba, Mn, B, Cs, and Zn, so they are chemically zoned. This zoining was accounted for in the determination of inclusion compositions. Fluid inclusions host two- (L, V) to five phase (L,V, and 3 solids) aqueous fluids. Depite this, their estimated bulk salinity is unexpectedly low (0.4-2.9 wt% NaCl eq.) and does not change systematically within the crystals. The Th(total) of all fluids is consistently in the 220-260 °C range and homogenzation occurs mainly by bubble disappearance. The main inclusion components are (in order of relative abundance) Na, K, B, Sr, Sb, Ba, Mn, Rb, Cs, Zn, Pb, and Cu, i.e., the same that make the quartz zoning.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
