Basin physiography and tectonic influence on sequence architecture and stacking pattern: Pleistocene succession of the Canoa Basin (central Ecuador)

Facies, shell bed features, and sequence stratigraphic framework for the shallow-marine Pleistocene upper Canoa and Tablazo Formations are presented, based on outcrop data from the southern coast of Cabo San Lorenzo, Ecuador. Sediments of this succession exhibit a distinct cyclic pattern, consisting of a stack of eight depositional sequences likely developed under the main control of orbitally induced sea-level changes. As a rule, within the studied interval an idealized cyclothem is composed of a transgressive systems tract (TST) and a highstand systems tract, whereas deposits attributable to the lowstand and falling-stage systems tracts are not present. Transgressive lithosomes may be defined by estuarine deposits interposed between the sequence boundary and the ravinement surface and by upward fining shoreface to inner-shelf facies successions above the ravinement (backstepping shelf wedge). Notwithstanding the different synsedimentary tectonic and climatic regimes, the Ecuadorian cyclothems share basic patterns of condensation and facies assemblages with other roughly coeval cyclothemic successions around the world. At a multicycle time scale, tectonics influenced the long-term trend of the relative sea-level changes and consequently the large-scale stratigraphic organization. Owing to the continued tectonic uplift of the area, successive high-frequency depositional sequences are nested to form a longer-order falling-stage sequence set.