Estudio de inclusiones fluidas en granitos microfisurados. Mineralizaciones de W-Sn del Sistema Central Español.

Resumen

The geometry of the ore fluid migration was investigated in the (W-Sn) mineralizated granites of the Spanish Central System. Based on microthermometry, Raman microprobe and textural relationships, six types of fluid inclusions have been distinguished: 1) Magmatic hypersaline aqueous fluid represented by Lw-s inclusions. 2) Metamorphic aquo-carbonic fluids represented as different types of fluid inclusions: (i) H2O-CO2-(CH4) fluids represented by Vc-w three phase inclusions at room temperature; (ii) H2O-CO2-CH4 fluids showing two-phase at room temperature with a low density volatile phase displaying a large variation of the CH4/CO2 ratio; (iii) H2O-CH4 fluids represented by Lw-m two-phase inclusions with a volatile phase entirely dominated by CH4. 3) Aqueous fluid sare shown by (iv) Lw1 and (v) Lw2 two phase inclusions with low to moderate salinity. Fluid trapping occurred in the granites by means of a complex succession of opening and reopening of microfracture network. NE-SW ductile-brittle cracks contains quartz-wolframite thus connected with FIP bearing aqueous-carbonic fluids. A later drop in CO2 es recorded in N140º-150° E, N100º-110ºE, N-5 and E-W. A latest fluid is represented by aqueous fluids crosscutting the precedent fluid inclusions planes.