PALEOTSUNAMIS EN EL REGISTRO GEOLÓGICO DE CUMANÁ, ESTADO SUCRE, VENEZUELA ORIENTAL
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Universidad Industrial de Santander
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En el presente trabajo de investigación se realiza un estudio geológico del complejo lagunar Los Patos, en un ambiente próximo costero y se busca verifcar la existencia de paleotsunamis en el oriente del país, mediante estudios sedimentológicos, geoquímicos y paleontológicos a través de núcleos no perturbados tomados en dicha albufera en la ciudad de Cumaná. Fueron analizados los núcleos L-Patos 09-01 y L-Patos 09-02, donde la geoquímica se aplicó al núcleo L-Patos 09-01 mediante difracción de rayos X, análisis de elementos mayoritarios (fuorescencia de rayos X –FRX-) y dataciones 14C, mientras el núcleo L-Patos 09-02 se utilizó para la realización de análisis de susceptibilidad magnética. Los resultados mostraron una secuencia cuaternaria de sedimentación típica de ambientes lagunares costeros, con un predominio de facies arcillosas y limosas, con escasos intervalos delgados de arenas muy fnas. Mineralógicamente, la fracción detrítica se encuentra representada por el cuarzo y minerales de arcilla (ilita y caolinita); ambos se presentan como constituyentes esenciales de los sedimentos. Así mismo, se presentan minerales evaporíticos como yeso y halita. Se establecieron cinco facies sedimentarias que mostraron características texturales químicas y mineralógicas diferentes. Así mismo, se demostró que las arenas limpias ubicadas en el tope de la secuencia, presentaron características sedimentológica (bases erosivas, geoquímica (aumento de Ca y S) y paleontológicas (restos de plantas y raíces), que permiten evidenciar la ocurrencia de paleotsunamis en la laguna Los Patos, Venezuela.
This paper is a geological research about the Los Patos lagoon complex, which is performed in the near coastal environment and its purpose is to verify the existence of paleotsunamis in the east of the country, by sedimentological, geochemical and paleontological studies through undisturbed cores taken in that lagoon of the Cumaná city. Two cores were examined, L-Patos 09-01 and L-Patos 09-02. The L-Patos 09-01 core was analyzed using geochemical methods like X-ray diffraction, major elements (X-ray fuorescence X-FRX) and 14C dating, while the L-Patos 09-02 core was used for the analysis of magnetic susceptibility. The results showed a typical sequence of Quaternary sedimentation of coastal lagoon environments, with a predominance of argillaceous and silty facies with few and thin intervals of very fne sand. Mineralogically, the detrital fraction is represented by quartz and clay minerals (illite and kaolinite); both are presented as essential constituents of the sediments. Also, evaporite minerals such as gypsum and halite are presented. Five chemical sedimentary facies were identifed according to the different mineralogical and textural characteristics. Also, it was shown that the clean sand located at the top of the sequence presented sedimentological characteristics (erosive bases, geochemistry (increased Ca and S) and paleontological (remains of plants and roots), that suggest the occurrence of paleotsunamis in Los Patos lagoon, Venezuela.
This paper is a geological research about the Los Patos lagoon complex, which is performed in the near coastal environment and its purpose is to verify the existence of paleotsunamis in the east of the country, by sedimentological, geochemical and paleontological studies through undisturbed cores taken in that lagoon of the Cumaná city. Two cores were examined, L-Patos 09-01 and L-Patos 09-02. The L-Patos 09-01 core was analyzed using geochemical methods like X-ray diffraction, major elements (X-ray fuorescence X-FRX) and 14C dating, while the L-Patos 09-02 core was used for the analysis of magnetic susceptibility. The results showed a typical sequence of Quaternary sedimentation of coastal lagoon environments, with a predominance of argillaceous and silty facies with few and thin intervals of very fne sand. Mineralogically, the detrital fraction is represented by quartz and clay minerals (illite and kaolinite); both are presented as essential constituents of the sediments. Also, evaporite minerals such as gypsum and halite are presented. Five chemical sedimentary facies were identifed according to the different mineralogical and textural characteristics. Also, it was shown that the clean sand located at the top of the sequence presented sedimentological characteristics (erosive bases, geochemistry (increased Ca and S) and paleontological (remains of plants and roots), that suggest the occurrence of paleotsunamis in Los Patos lagoon, Venezuela.
Keywords
Coastal lagoon, Tsunami, Facies, X-ray, 14C dating, Lagunas costeras, Tsunami, Facies, Rayos-X, Datación 14C