Estudio de los paleofluidos en la Formación Silgará y su relación con procesos de deformación. Sector Aratoca-Pescadero (SW del Macizo de Santander).
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Universidad Industrial de Santander
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La Formación Silgará que aflora en la franja Pescadero-Aratoca presenta una estructura termal definida por las zonas metamórficas de la silimanita, estaurolita-distena, granate y biotita. Una franja de aproximadamente 120 m de espesor, localizada en el límite de la zonas estaurolita-distena y granate, presenta una gran profusión de venas hidrotermales (boudinadas) paralelas a la esquistosidad regional. Este hecho, junto con otras estructuras de deformación (pliegues isoclinales recumbentes, etc.), sugieren la presencia de una importante banda de cizallamiento que favoreció la circulación de fluidos, desarrollada durante una etapa extensiva, temporalmente asociada a la exhumación de esta unidad metamórfica.Los estudios microtermométricos en inclusiones fluidas (IF) en venas, principalmente de cuarzo, permiten identificar seis pulsos hidrotermales que afectaron a la Formación Silgará, durante su etapa retrógrada. Composicionalmente, estos paleofluidos pueden ser agrupados en acuoso-salinos (H2O+NaCl) y complejos (H2O+NaCl+CO2+CH4+/N2+H2S?).
The Silgará Formation that crops out in the Pescadero-Aratoca area presents a thermal structure defined by the metamorphic zones of the sillimanite, staurolite-distene, garnet and biotite. A band of approximately 120 m in width, located in the boundary between the staurolite-distene zone and garnet zone, presents a high amount of hydrothermal veins (boudinated) parallel to the regional schistosity. This fact, along with another deformation structures (isoclinal, recumbent folds, etc.), suggests the presence of an important shear band that favored the circulation of fluids, which was developed during an extensive stage, temporally associated to the exhumation of this metamorphic unit.The microthermometric studies in fluid inclusions (IF) in veins, mainly compossed by quartz, let to identify six hydrothermal events that affected the Silgará Formation, during its retrograde stage. Compositionally, these paleofluids can be gruped in aquose-salines (H2O+NaCl) and complexes (H2O+NaCl+CO2+CH4+/N2+H2S?).
The Silgará Formation that crops out in the Pescadero-Aratoca area presents a thermal structure defined by the metamorphic zones of the sillimanite, staurolite-distene, garnet and biotite. A band of approximately 120 m in width, located in the boundary between the staurolite-distene zone and garnet zone, presents a high amount of hydrothermal veins (boudinated) parallel to the regional schistosity. This fact, along with another deformation structures (isoclinal, recumbent folds, etc.), suggests the presence of an important shear band that favored the circulation of fluids, which was developed during an extensive stage, temporally associated to the exhumation of this metamorphic unit.The microthermometric studies in fluid inclusions (IF) in veins, mainly compossed by quartz, let to identify six hydrothermal events that affected the Silgará Formation, during its retrograde stage. Compositionally, these paleofluids can be gruped in aquose-salines (H2O+NaCl) and complexes (H2O+NaCl+CO2+CH4+/N2+H2S?).
Keywords
Metamorphism, fluid inclusions, shear band, Silgará Formation, Metamorfismo, inclusiones fluidas, banda de cizallamiento, Formación Silgará