Magnetic Petrology applied to the characterization of Pegmatite Dykes in Eastern Colombia
-
Published:2023-05-23
Issue:1
Volume:27
Page:11-25
-
ISSN:2339-3459
-
Container-title:Earth Sciences Research Journal
-
language:
-
Short-container-title:Earth sci. res. j.
Author:
Charry Carlos José,Molano Juan Carlos,Santacruz Leonardo,Sepulveda Janeth
Abstract
In the sector of San Jose, Macanal, and Tabaquen, in eastern Colombia, granitic rocks cut by pegmatite dikes and quartz veins appear with the presence of magnetite, ilmenite, and ilmenorutile. Using magnetic petrology and geochemistry concepts and methods, the main objective is to determine if these types of rocks are genetically related and how the fluid chemically evolves during its crystallization and cooling. This work was conducted in three stages. Petrography and opaque metallography for identifying the occurrence, paragenesis, and secondary processes that transform the oxides. In a second stage and utilizing an Electron Probe Microanalyzer (EPMA), 214 quantitative analyses (WDS) and four compositional maps for magnetite, ilmenite, and ilmenorutile were performed, measu- ring the oxides FeO, TiO2, V2O3, MgO, MnO, Nb2O5, Ta2O5, Al2O3, Ga2O3, NiO, CaO, Cr2O3, SnO, and WO3. Since magnetite and ilmenite are favorable geothermometers that also allow the calculation of oxygen fugacity, the ILMAT program was used to calculate these values. In closing, integrate the data with the magnetic susceptibility values. The results determine crystallization temperatures between 358-414 °C for the granitic-host rock and 402- 499 °C for pegmatites dykes, in a system where oxygen fugacity increases, the Mn2+ is enriched in the ilmenite, and magnetite preserves a low content of trace elements thorough the evolution of the fluid. Taken together with the martitization and exsolution of hematite and rutile within ilmenite found in the petrography, these results allow us to conclude that an oxide-silicate re-equilibration process controls the evolution of this magmatic-hy- drothermal fluid with a KUIlB cooling trend-type reaction. Based on the Al + Mn vs. Ti + V ratio, the signature of the magnetite is like the Lucky Friday mine’s signature studied by Nadoll. However, the analysis of the 95th percentile shows a different concentration of trace elements in the magnetite of both sectors. Therefore, a new field of discrimination is proposed for this environment of anorogenic pegmatites of the NYF family. Finally, the magnetic susceptibility is controlled only by the abundance of magnetite in each type of rock. The granitic host rocks have the highest susceptibility values, followed by pegmatites and quartz veins with the lowest.
Publisher
Universidad Nacional de Colombia
Subject
General Earth and Planetary Sciences
Reference46 articles.
1. Aronsson, J. (2016). Compositional variations between hydrothermal and magmatic magnetite and their potential for mineral exploration using till from Laver, Northern Sweden. University of Gothenburg. ISSN: 1400-3821. 2. Bacon, C. R., & Hirschmann, M. M. (1988). Mg/Mn partitioning as a test for equilibrium between coexisting Fe-Ti oxides. American Mineralogist, 73, 57–61. 3. Barrera, D., & Molano, J. C. (2021). Characterization of hydrothermal events associated with the occurrence of copper-molybdenum minerals in the El Chucho creek at Cerrito, Valle del Cauca-Colombia. Earth Sciences Research Journal, 25(1), 5–12. https://doi.org/10.15446/esrj.v25n1.79152 4. Bonilla-Pérez, A., Frantz, J. C., Charao-Marquez, J., Cramer, T., Franco-Victoria, J. A., Mulocher, E., & Amaya-Perea, Z. (2013). Geocronologia Del Granito De Parguaza, Boletín de Geología, 35 (2). 5. Bowles, J., Howie, R., Vaughan DPhil, D., & Zussman, J. (2011). Non-silicates: Oxides, Hydroxides, and Sulphides. Rock-Forming Minerals, 5A (2). ISSN: 2041-6296. London.
Cited by
1 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|