PALEOTSUNAMIS IN THE GEOLOGICAL RECORD OF CUMANÁ, SUCRE STATE, EASTERN VENEZUELA

Abstract

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.