| TAZ-TFG-2019-4226 |
Paleosuelos lateríticos desarrollados en el Barremiense de la Cordillera Ibérica (Provincia de Teruel)
Carramiñana Agustin, Diego
Bauluz Lázaro, Blanca. (dir.) ; Canudo Sanagustín, José Ignacio. (dir.)
Universidad de Zaragoza,
CIEN,
2019
Departamento de Ciencias de la Tierra,
Graduado en Geología
Resumen: This work focuses on the study of paleosoils developed on continental facies, in order to determine its type, texture and mineralogy, genesis and the paleoenvironmental and paleoclimatic conditions during its formation. The three studied outcrops are located within the Oliete Sub-Basin, in the Maestrazgo Basin. The materials studied with red, yellow and violet colours were developed on continental facies sedimented during the early Barremian (Lower Cretaceous). Many of the samples contain ferruginous pisoliths. The study was carried out by means of an exploration and sampling in the field, and the application of various laboratory techniques such as: description of hand samples, X-ray diffraction (XRD), optical microscopy and field emission scanning electron microscopy (FESEM).
The XRD allowed observing that the mineralogy of the study materials consists of carbonates and silicates. Hematite, goethite, and different types of clay minerals such as kaolinite, smectite, palygorskite and illite were also detected in the three outcrops. The amount of clay minerals and iron oxides/oxyhydroxides was greater near the limit with the carbonates of the Jurassic. In addition, the kaolinite predominated over the rest of the clay minerals. The characteristics of the paleosoils such as their colour and the presence of abundant kaolinite, hematite, goethite and ferruginous pisoliths indicate that they can be classified as laterite.
Optical microscopy and FESEM studies were focused on the VE outcrop. The occurrence of book-like aggregates of kaolinite plates and smectite flakes indicate that they have an authigenic origin. Their crystallization implies the dissolution of previous aluminosilicates (such as K feldspars or micas). The hematite and the goethite were probably authigenic, since they were found in large quantities within the pisoliths. The quartz fragments are detrital, their small size and rounded appearance could be due, at least partially, to the dissolution process that involves the development of soil. The illites are scarce and have not been observed by microscopy, their formation is not compatible with the formation of kaolinite, so they are probably detrital. There is also no textural data of the palygorskite and it might be detrital, but its chemical composition (rich in magnesium), allows us to establish the hypothesis that they were formed during lacustrine stages. Carbonates have different textures (micritic, microsparitic and sparitic textures), which could be a consequence of the generation of lacustrine carbonated mud and subsequent recrystallizations of this carbonate during diagenesis. Some of these lacustrine carbonate levels contain pisoliths and minor amounts of kaolinite suggesting they also were affected by the paleosoil formation. These diagenetic processes do not modify significantly the mineralogy of the paleosoils.
Kaolinite formation needs hydrolysis processes, which requires sedimentary environments with oxidizing conditions, hot and humid climate. The fact that the kaolinite, goethite and hematite were more abundant in the lower part of the Blesa Formation, indicates that the climate was more humid and hot when the development of the paleosol at the bottom and progressively changed to warmer conditions, or alternatively the weathering was more effective in these lower materials as a consequence of the outcrops characteristics.
The laterization affected to the lower member of the Blesa Formation. The Jurassic materials and the intermediate member of the Blesa Formation were not affected by lateritic processes.
The XRD allowed observing that the mineralogy of the study materials consists of carbonates and silicates. Hematite, goethite, and different types of clay minerals such as kaolinite, smectite, palygorskite and illite were also detected in the three outcrops. The amount of clay minerals and iron oxides/oxyhydroxides was greater near the limit with the carbonates of the Jurassic. In addition, the kaolinite predominated over the rest of the clay minerals. The characteristics of the paleosoils such as their colour and the presence of abundant kaolinite, hematite, goethite and ferruginous pisoliths indicate that they can be classified as laterite.
Optical microscopy and FESEM studies were focused on the VE outcrop. The occurrence of book-like aggregates of kaolinite plates and smectite flakes indicate that they have an authigenic origin. Their crystallization implies the dissolution of previous aluminosilicates (such as K feldspars or micas). The hematite and the goethite were probably authigenic, since they were found in large quantities within the pisoliths. The quartz fragments are detrital, their small size and rounded appearance could be due, at least partially, to the dissolution process that involves the development of soil. The illites are scarce and have not been observed by microscopy, their formation is not compatible with the formation of kaolinite, so they are probably detrital. There is also no textural data of the palygorskite and it might be detrital, but its chemical composition (rich in magnesium), allows us to establish the hypothesis that they were formed during lacustrine stages. Carbonates have different textures (micritic, microsparitic and sparitic textures), which could be a consequence of the generation of lacustrine carbonated mud and subsequent recrystallizations of this carbonate during diagenesis. Some of these lacustrine carbonate levels contain pisoliths and minor amounts of kaolinite suggesting they also were affected by the paleosoil formation. These diagenetic processes do not modify significantly the mineralogy of the paleosoils.
Kaolinite formation needs hydrolysis processes, which requires sedimentary environments with oxidizing conditions, hot and humid climate. The fact that the kaolinite, goethite and hematite were more abundant in the lower part of the Blesa Formation, indicates that the climate was more humid and hot when the development of the paleosol at the bottom and progressively changed to warmer conditions, or alternatively the weathering was more effective in these lower materials as a consequence of the outcrops characteristics.
The laterization affected to the lower member of the Blesa Formation. The Jurassic materials and the intermediate member of the Blesa Formation were not affected by lateritic processes.
Tipo de Trabajo Académico: Trabajo Fin de Grado
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