| TAZ-TFG-2024-4594 |
Formación de filosilicatos 1:1 por alteración hidrotermal de rocas ácidas: Transformaciones minerales y químicas.
Alvira Gómez, Sergio
Bauluz Lázaro, Blanca (dir.) ; Yuste Oliete, Alfonso (dir.)
Universidad de Zaragoza,
CIEN,
2024
Departamento de Ciencias de la Tierra,
Graduado en Geología
Resumen: This Final Degree Project shows an analysis that aims to determine the mineralogical transformations that occur when 1:1 phyllosilicates are formed from acidic rocks due to hydrothermal alteration.
1:1 phyllosilicates are formed in nature by low-temperature processes (≤ 200◦C), and their formation and subsequent modifications are controlled by time, temperature, burial depth and fluid/rock ratio, with dissolution-crystallization processes being those that form and transform 1:1 phyllosilicate minerals.
The chemical changes and mineral transformations that occur in the formation of 1:1 phyllosilicates through hydrothermal alteration are produced due to the alteration of rocks by hot water circulating in the Earth's crust, with the Burela kaolin deposit being a great example of these processes because it is a volcanic deposit which has undergone hydrothermal alteration, converting the granite in the area into kaolin.
This study aims to determine the mineralogical transformations that have taken place in the alteration process, as well as some chemical modifications that this alteration implies from the samples obtained from the Burela deposit.
Based on the samples obtained from the deposit and the methodology used to obtain information from these samples (interpretation of the diffractograms obtained from the samples, semi-quantitative analysis and FESEM), it has been observed how hydrothermal alteration has progressed from fresh granite to kaolin, passing through altered granite and super-altered granite.
From the data obtained from the samples, it has been observed that the fresh granites and the altered granites do not show significant changes in the mineralogical composition caused by the alteration, indicating a low activity of the hydrothermal fluid causing the hydrothermal alteration. It is only from the super-altered granites that a significant change in the mineralogical composition has been observed, indicating a higher activity of the hydrothermal fluid causing the hydrothermal alteration.
The hydrothermal alteration undergone by the samples reflects a high fluid/rock ratio and significant dissolution processes since no intermediate alterations are observed between the feldspars or quartz and kaolinite during the dissolution/crystallization processes. Kaolinite uses mica sheets as a substrate to grow since no traces of alteration are observed in the mica sheets. During alteration, partial dissolution of uranium in zircons and niobium occurs, incorporating them into the oxides formed during the alteration.
At the end, kaolinite formed present a high degree of development of the kaolinite particles, in the form of book-shaped aggregates, due to the dissolution/crystallization processes that have occurred during the alteration.
1:1 phyllosilicates are formed in nature by low-temperature processes (≤ 200◦C), and their formation and subsequent modifications are controlled by time, temperature, burial depth and fluid/rock ratio, with dissolution-crystallization processes being those that form and transform 1:1 phyllosilicate minerals.
The chemical changes and mineral transformations that occur in the formation of 1:1 phyllosilicates through hydrothermal alteration are produced due to the alteration of rocks by hot water circulating in the Earth's crust, with the Burela kaolin deposit being a great example of these processes because it is a volcanic deposit which has undergone hydrothermal alteration, converting the granite in the area into kaolin.
This study aims to determine the mineralogical transformations that have taken place in the alteration process, as well as some chemical modifications that this alteration implies from the samples obtained from the Burela deposit.
Based on the samples obtained from the deposit and the methodology used to obtain information from these samples (interpretation of the diffractograms obtained from the samples, semi-quantitative analysis and FESEM), it has been observed how hydrothermal alteration has progressed from fresh granite to kaolin, passing through altered granite and super-altered granite.
From the data obtained from the samples, it has been observed that the fresh granites and the altered granites do not show significant changes in the mineralogical composition caused by the alteration, indicating a low activity of the hydrothermal fluid causing the hydrothermal alteration. It is only from the super-altered granites that a significant change in the mineralogical composition has been observed, indicating a higher activity of the hydrothermal fluid causing the hydrothermal alteration.
The hydrothermal alteration undergone by the samples reflects a high fluid/rock ratio and significant dissolution processes since no intermediate alterations are observed between the feldspars or quartz and kaolinite during the dissolution/crystallization processes. Kaolinite uses mica sheets as a substrate to grow since no traces of alteration are observed in the mica sheets. During alteration, partial dissolution of uranium in zircons and niobium occurs, incorporating them into the oxides formed during the alteration.
At the end, kaolinite formed present a high degree of development of the kaolinite particles, in the form of book-shaped aggregates, due to the dissolution/crystallization processes that have occurred during the alteration.
Tipo de Trabajo Académico: Trabajo Fin de Grado
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Trabajos académicos > Trabajos Académicos por Centro > Facultad de Ciencias
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