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With hull-mounted multibeam echosounder data, we report for the first time along the active Ecuadorian margin, acoustic signatures of water column fluid emissions and seep-related structures on the seafloor. In total 17 flare-shaped acoustic anomalies were detected from the upper slope (1250 m) to the shelf break (140 m). Nearly half of the flare-shaped acoustic anomalies rise 200-500 m above the seafloor. The base of the flares is generally associated with high-reflectivity backscatter patches contrasting with the neighboring seafloor. We interpret these flares as caused by fluid escape in the water column, most likely gases. High-resolution seismic profiles show that most flares occur close to the surface expression of active faults, deformed areas, slope instabilities or diapiric structures. In two areas tectonic deformation disrupts a Bottom Simulating Reflector (BSR), suggesting that buried frozen gas hydrates are destabilized, thus supplying free gas emissions and related flares. This discovery is important as it opens the way to determine the nature and origin of the emitted fluids and their potential link with the hydrocarbon system of the forearc basins along the Ecuadorian margin.

Selected high-resolution seismic-reflection profiles and multibeam bathymetry acquired along the convergent Ecuador margin during the ATACAMES cruise on onboard the R/V L'Atalante (Jan.15-Feb.18, 2012) allow a preliminary evaluation of the neotectonic development and stratigraphic evolution of the margin based on the sismo-stratigraphic analysis of Quaternary sediment preserved on the margin shelf and upper slope. We present three major preliminary results. (1) The evolution of the Esmeraldas, Guayaquil and Santa Elena canyons. The head of the Esmeraldas canyon is the location of a continuous significant sediment transport. The Guayaquil canyon shows several episodes of deposition and incision. Aggrading sedimentation pattern in the canyon records several changes in relative sea-level. The subsidence of the Gulf of Guayaquil probably contributes to the good preservation of the canyon filling stages. The Santa Elena canyon is controlled by a SW-NE trending normal fault. (2) Variations of sediment accumulation and relative vertical motions are shown along-strike the shelf edge. Offshore the uplifted Manta peninsula, a pronounced subsidence of the shelf edge is documented by sedimentary clinoforms that have deposited in a morphological reentrant, and have migrated upslope testifying of a local subsidence meanwhile the adjacent La Plata Island area underwent uplift. In the Esmeraldas canyon area, a local uplift of the shelf is documented. (3) Two neotectonic fault systems with a possible transcurrent component are imaged across the shelf edge and upper margin slope offshore Jama, and Cape Galera. This possible transcurrent motion could be related to the reactivation of ancient faults of the upper plate by the subduction. These preliminary results indicate that the ATACAMES data set has a strong potential to evaluate the spatial and temporal contribution of tectonic and climate changes on the structural development and stratigraphic evolution of the Ecuador continental margin.

International audience; The great variety of climatic conditions, tidal ranges and wave regimes of South and Central America act on a complex geology and tectonic framework. Many of the rock and cliffed coasts of South America are strongly controlled by the occurrence of extensive Cenozoic and Pleistocene sediments that crop out at the coast. Geology and the different uplift rates are a major factor in the whole coastal geomorphology of South and Central America, and consequently are a very important control of the processes and landforms of rock coasts. This chapter covers several aspects of the rock coast of South and Central America, with special attention to the combination of tectonic movements and Quaternary Pleistocene– Holocene sea-level changes.

The great variety of climatic conditions, tidal ranges and wave regimes of South and Central America act on a complex geology and tectonic framework. Many of the rock and cliffed coasts of South America are strongly controlled by the occurrence of extensive Cenozoic and Pleistocene sediments that crop out at the coast. Geology and the different uplift rates are a major factor in the whole coastal geomorphology of South and Central America, and consequently are a very important control of the processes and landforms of rock coasts. This chapter covers several aspects of the rock coast of South and Central America, with special attention to the combination of tectonic movements and Quaternary Pleistocene–Holocene sea-level changes.

El presente estudio realiza un análisis morfoestructural de las plataformas que están en el territorio marìtimo ecuatoriano:(1)La Plataforma de las Islas Galápagos que es producto de la interacción entre el Punto Caliente de Galápagos y el Centro de Divergencia de Galápagos, y (2) La Plataforma Continental del Ecuador continental localizada en un margen activo convergente entre la placa oceánica de Nazca y los segmentos continental de la placa Sudamericana y del Bloque Norandino. Mediante el uso de Sistemas de Información Geográfica (SIG) y Modelos Digitales de Terreno (MDT), se caracterizó morfológicamente la proyección de la plataforma continental hacia el segmento marino, para luego realizar una confrontación entre el área que incluye la plataforma geológica con el área que se genera a partir de la aplicación del Art. 76 de la CONVEMAR en donde se define la plataforma jurídica. El análisis morfológico determinó que el Ecuador, tiene una plataforma geológica en su territorio continental con un ancho promedio de 54 MN (Millas Náuticas), teniendo su máxima extensión en el Golfo de Guayaquil con 95 MN. El área total en el segmento continental es de 38.000 Km2. La plataforma insular que se extiende direccionalmente a través de las cordilleras submarinas de Carnegie, Colón y Cocos, abarca un área de 627.820 km2. Al generar las plataformas jurídicas a partir de las líneas de base que tiene el Ecuador, éstas abarcan un área de 237.038 Km2 en el territorio continental comprendiendo la plataforma geológica, la fase Ecuador y el sector Oriental de la Cordillera de Carnegie y de 855.104 km2 en el territorio insular, incluyendo gran parte de la plataforma geológica insular, y algunos sectores de las cuencas océanicas de Perú y Panamá. Al contrastar las áreas entre las plataformas geológicas con las plataformas jurídicas, se obtiene que el Ecuador se beneficiaría con la plataforma jurídica con un área de 426.322 Km2. This study supplies useful morphostructural data for the whole Ecuadorian shelf : the Galapagos Island shelf is the result of ascending magmatic processes among the Galapagos Hotspot and the Galapagos Spreading Center, while Ecuadorian continental shelf located in an active convergent boundary between the Nazca plate and the South American plate to southern continental site and the North Andean Block crustal segments to the northern continental site. Using Geographic Information Systems (GIS) and Digital Terrain Models (DTM), we have been characterized morphologically the spreading out of the oceanic crust, and then, its relationship with the Galapagos spreading center and define the natural shelf in concordance to the Article 76 of the UNCLOS. Morphological analyses in the whole continental Ecuadorian territory evidence a natural shelf 54 MN of length, allow it maximum enlargement in the Guayaquil Gulf with lenght of 95 MN with an area of 38.000 km2; furthermore the Insular shelf is long-drawn-out through the high bathymetrical Carnegie, Colon and Cocos ridges reach about 627.820 km2 in the area Studied. The Ecuadorian lawful shelves delineated from baselines, an addition, it reach about 237.038 km2 in the Ecuadorian territory that include the carry-over natural shelf, the Ecuadorian tectonic trench and the eastern parts of the high Carnegie, with an area of ca. 855.104 km2 for the igneous Galapagos Province, includes part of the natural shelf and the Cocos, Colon and Carnegie ridge. An integration of contrasting research areas as the natural shelf with lawful shelf, it would allow the extension for Ecuadorian shelf in about 426.322 km2. Published