Geochemical Analysis for Sedimentary Emerald Mineralization in Western Emerald belt, Colombia Gabriel Felipe Nino Vasquez and Sheng-Rong Song Department of Geosciences, National Taiwan University
INTRODUCTION METHODS AND RESULTS CONCLUSIONS
Legend 2.PETROGRAPHY km 1. FIELD TRIP Alluvial deposits 0 5 Luna Formation Muzo Formation 1 Rosablanca Formation Cross Cutting Plastic deformation, and Qz with waved extintion, Carbonate recrystalization, d13C_PDB/d18O_PDB Fault fractures and Veins fractured veins breciation and deformation twims Emerald Mine 4
2
0 -14 -12 -10 -8 -6 -4 -2 0 La Pita 3 2 Coscuez -2 Monteblanco Cunas
La Pita d13C_PDB 2 1 mm. -4 Españoles Puerto Sanin -6 Masatos
-8 Productive carbonates identification 3. 4 -10 d18O_PDB
* All the samples show a sedimentary / metamorphic origin. Fibrous Geode Orthorhombic * GROUP 2 that produces more emeralds than any other area shows higher d18O values, which means that the composition Emeralds in Colombia are generated mainly in black shale, and are located in the Eastern d13C_PDB/d18O_SMOW (‰) of the fluid is not exactly the same. The For Original fluid (315°C) fluid in this area is more evolved and Andes Cordillera in two parallel belts separated by approximately 130 Km: Western belt 2 reactive (WB) and Eastern belt (EB). The geological, mineralogical and tectonic features from these * Productive veins show higher d18O and 0 belts are quite similar. 20 22 24 26 28 30 32 lower d13C values. -2 La Pita Coscuez * This proxyes result important for -4 Monteblanco Previous researchers concluded that Emeralds in Colombia come from hydrothermal Cunas emerald exploration in the Colombian -6 Espanoles Western Emerald Belt. sedimentary processes without any magmatic influence , which would be an unique Puerto Sanin deposit around the world. They suggested that the source of Cr, V and Be is the host rock -8 Masatos (Giuliani et al. 1994). -10
-12 d18O_PDB Emerald minerallization in the WB are founded in multidirectional veins and breccias hosted by the black shale in paragenesis with carbonates (calcite, dolomite, ankerite), 36 samples from 7 different mines along the WE were collected . All of them are carbonates deposited in BIBLIOGRAPHY albite, pyrite, chalcopyrite, quartz, etc. G. GIULIANI Á C. et al., (1998). Oxygen isotope systematics of emerald: relevance for its originand geological signicance. Mineralium Deposita, Pp 513-519. veins, breccia and shales from the Muzo formation. Different Parameters like: Crystal habit, paragenesis, ROLLINSON, H., (1996). Using geochemical data: evaluation, presentation, interpretation. Longman (ed.). Pp. 352. L. Mantila et al., (2007) investigación petrográfica y geoquímica de las sedimentitas del cretácico inferior (k1) y sus manifestaciones hidrotermales asociadas; location and productive history were considered in order to define productive and non productive veins planchas 169, 170, 189, 190 (cordillera oriental): implicaciones en la búsqueda de esmeraldas.