Deciphering Turbidite Triggers by Core Facies Analyses. Implications for Geohazards and Reservoir Characterization

Sediment cores retrieved in turbidite sediments from modern lacustrine systems enable to understand the sedimentological processes and depositional patterns of turbiditic flows as well as to evaluate their triggering mechanisms. Lacustrine turbidites were analysed in Lake Montcortès situated in NE Iberian Peninsula (42º 19´N / 0º 59´E). Multiproxy core facies analyses were applied to investigate the turbidite record of this karstic lake system. Integration of geochemical, geophysical and sedimentological analyses and micro-computed tomography (micro-CT) imaging led to the identification of two types of turbidites and distinct triggers have been proposed to generate them: i) low density turbidity currents resulting from sediment-laden hyperpycnal currents related to extreme floods in the watershed and ii) seismic-induced subaquatic slope failures. Geohazard assesments can be implemented by understanding the variability of these extreme events (earthquakes, tsunamis and large floods) preserved in the sedimentary record at centennial to millennial scales. In addition, deciphering triggering mechanims in core facies analyses may have significant economic implications as both processes eventually lead to different turbidites geometries and textures that may affect reservoir quality although lacustrine turbidites are not the most common hydrocarbon reservoirs.