RT Journal Article
T1 As–(Ag) sulphide veins in the Spanish Central System:further evidence for a hydrothermal event of Permian age
A1 Martín Crespo, Tomás
A1 Vindel, Elena
A1 López García, José Ángel
A1 Cardellach, Esteve
AB The Spanish Central System (SCS) has been subjected to repeated deformation and fluid flow events which have producedboth sulphide-bearing and barren vein systems. Although several hydrothermal episodes took place between 300 and 100 Ma,fluid circulation during the Permian was especially important, giving rise to a range of different types of deposits. This studypresents a multidisciplinary approach leading to the characterisation of the chemistry and age of the hydrothermal fluids thatproduced the As–(Ag) mineralised stockwork of Mo´nica mine (Bustaviejo, Madrid). Fluid inclusion data indicate the presenceof two different fluids. An initial ore stage (I) formed from a low- to moderate salinity (3–8 wt.% eq. NaCl) H2O–NaCl–CO2–CH4 fluid, at minimum trapping temperature of 350±15 ºC and 0.3 kbar. A second H2O–NaCl fluid is found in three types offluid inclusions: a high temperature and low salinity type (340±20 ºC; 0.8–3.1 wt.% eq. NaCl) also associated to ore stage I, amoderate temperature and very low salinity type (160–255 ºC; 0–1.5 wt.% eq. NaCl) represented in ore stage III, and a verylow temperature and hypersaline type (60–70 ºC; 30–35 wt.% NaCl), unrelated to the mineralising stages and clearlypostdating the previous types. 40Ar–39Ar dating on muscovite from the early As–Fe stage (I) has provided an age of 286±4Ma, synchronous with the late emplacement phases of La Cabrera plutonic massif (288±5 Ma) and with other Permianhydrothermal events like Sn–W skarns and W–(Sn) sulphide veins. δ18O of water in equilibrium with stage I quartz (5.3–7.7x), δD of water in equilibrium with coexisting muscovite (-16.0‰ to -2.0‰), and sulphide δ34S (1.5–3.6‰) values arecompatible with waters that leached metamorphic rocks. The dominant mechanism of the As–(Ag) deposition was mixing anddilution processes between aqueous–carbonic and aqueous fluids for stage I (As–Fe), and nearly isobaric cooling processes forstages II (Zn–Cu–Sn) and III (Pb–Ag). The origin and hydrothermal evolution of As–(Ag) veins is comparable to otherhydrothermal Permian events in the Spanish Central System.
PB Elsevier Science B.V., Amsterdam
SN 0169-1368
YR 2004
FD 2004
LK https://hdl.handle.net/20.500.14352/50080
UL https://hdl.handle.net/20.500.14352/50080
LA eng
DS Docta Complutense
RD 6 may 2024