Thick-skinned tectonics in the Oriente foreland basin of Ecuador

The Oriente Basin is part of the retro-arc foreland basin system that developed in the zone of transition between the Central Andes and the Northern Andes since Late Cretaceous times. It is deformed by thick-skinned tectonics related to the inversion of pre-Cretaceous extensional fault systems, which have broken the basin into three tectonic domains during three mean periods of inversion (Late Cretaceous-Palaeocene, Early Eocene and Miocene). The northern part of the present-day Sub-Andean wedge-top corresponded, during the Late Cretaceous, to the forebulge depozone. The NNE-SSW Sacha-Shushufindi Corridor (SSC) extends from the northern region of the Oriente foredeep to the Sub-Andean CutucùCordillera. It results from inversion of the Late Triassic-Early Jurassic rifting. The eastern Capiron-Tiputini Inverted System (CTIS) results from the inversion of the normal faults of the Late Jurassic back-arc basin. The Ishpingo- Tambococha-Tiputini (ITT) trend is located in the present-day forebulge depozone of the basin. This position presents favourable conditions for oil biodegradation. Source rocks throughout the Oriente Basin are immature or poorly mature. A large part of oil accumulations must be explained by long-distance migration from the west, before the Eocene uplift of the Cordillera Real, or from the south.