The “Celica–Lancones” forearc Basin of southern Ecuador and northern Peru is located between the Paleozoic Amotape–Tahuin Massif to the west and NW and the continental volcanic arc to the east and ...SE. The study of nine sections and exhaustive sampling of the poorly fossiliferous, mainly clastic Cretaceous deposits of this Basin allowed us to define five distinct series, which display two depositional periods.
The first period corresponds to the development of an Early (?) and Middle Albian carbonate shelf, interrupted during Late Albian times by the creation of a tectonically generated trough filled by turbidites of Late Albian–Coniacian age. Geological mapping indicates that this “Celica–Lancones Basin
s.s.” includes distinct tectonic units, characterized by distinct early Late Cretaceous stratigraphic series and separated by major faults. These units can be grouped into two main paleogeographic domains. The southeastern one comprises mainly volcaniclastic deposits, whereas the northwestern domain exhibits quartz-rich deposits.
Between Early Coniacian and Middle Campanian times, the “Celica–Lancones Basin
s.s.” forerarc trough was deformed and eroded as a result of the Late Cretaceous “Peruvian” tectonic phase. The second period corresponds to the latest Cretaceous, during which a new forearc basin was created (Paita–Yunguilla Basin), which is much wider and strikes obliquely with respect to the Celica–Lancones Basin. The sediments of the Paita–Yunguilla Basin exhibit a comparable succession of Campanian–Maastrichtian age throughout the area and conceal the tectonic juxtaposition of the early Late Cretaceous tectonic units. The occurrence of thick Early(?) Maastrichtian coarse-grained conglomerates and breccias express a new significant tectonic event.
La “cuenca” de ante-arco de Celica–Lancones del Suroeste de Ecuador y Noroeste del Perú está ubicada entre el Macizo paleozoico de Amotape–Tahuin al Oeste y el arco volcánico continental al Este y SE. El estudio de una decena de secciones de campo y el muestreo de estos depósitos cretácicos mayormente clásticos y poco fosilı́feros permite definir cinco series distintas, que evidencian dos perı́odos de depositación.
El primer perı́odo corresponde al desarrollo de una plataforma carbonatada de edad Albiana inferior (?) a medio, interrupido en el Albiano superior por la creación de una cuenca turbidı́tica tectonicamente activa. El mapeo geológico demuestra que la “Cuenca Celica–Lancones
s.s.” incluye unidades tectónicas distintas con diferentes series estratigráficas de edad Cretáceo superior temprano, separadas por fallas mayores. Las unidades pueden ser agrupadas en una provincia paleogeográfica suroriental caracterizada por depósitos mayormente volcanoclásticos, y un dominio noroccidental marcado por depósitos clásticos ricos en cuarzo detrı́tico.
Entre el Coniaciano inferior y el Campaniano medio, la cuenca de “Celica–Lancones
s.s.” fue deformada y erosionado (“Fase Peruana” del Cretáceo superior). El segundo perı́odo corresponde al Cretáceo terminal, durante el cual se formó una nueva cuenca de ante-arco (Cuenca Paita–Yunguilla) caracterizada por una serie Campano-Maastrichtiana homogénea en toda el área, que sella la yuxtaposición tectónica de las unidades pre-santonianas. Más luego, la ocurrencia de potentes conglomerados y brechas de grano grueso en el Maastrichtiano (?)temprano espresa un nuevo evento tectónico importante.
The "Celica-Lancones" forearc Basin of southern Ecuador and northern Peru is located between the Paleozoic Amotape-Tahuin Massif to the west and NW and the continental volcanic arc to the east and ...SE. The study of nine sections and exhaustive sampling of the poorly fossiliferous, mainly clastic Cretaceous deposits of this Basin allowed us to define five distinct series, which display two depositional periods.The first period corresponds to the development of an Early (?) and Middle Albian carbonate shelf, interrupted during Late Albian times by the creation of a tectonically generated trough filled by turbidites of Late Albian-Coniacian age. Geological mapping indicates that this “Celica-Lancones Basin s.s.” includes distinct tectonic units, characterized by distinct early Late Cretaceous stratigraphic series and separated by major faults. These units can be grouped into two main paleogeographic domains. The southeastern one comprises mainly volcaniclastic deposits, whereas the northwestern domain exhibits quartz-rich deposits.Between Early Coniacian and Middle Campanian times, the “Celica-Lancones Basin s.s.” forerarc trough was deformed and eroded as a result of the Late Cretaceous “Peruvian” tectonic phase. The second period corresponds to the latest Cretaceous, during which a new forearc basin was created (Paita-Yunguilla Basin), which is much wider and strikes obliquely with respect to the Celica-Lancones Basin. The sediments of the Paita-Yunguilla Basin exhibit a comparable succession of Campanian-Maastrichtian age throughout the area and conceal the tectonic juxtaposition of the early Late Cretaceous tectonic units. The occurrence of thick Early(?) Maastrichtian coarse-grained conglomerates and breccias express a new significant tectonic event.
Le Bassin d'avant-arc de Celica-Lancones du Sud-Ouest de l'Equateur et Nord-Ouest du Pérou est situé entre le Massif paléozoïque de Amotape-Tahuin à l'Ouest et l'arc volcanique continental crétacé à l'Est et au Sud-Est. L'étude de 9 coupes et l'échantillonnage systématique des dépôts clastiques peu fossilifères crétacés de ce bassin a permis de définir 5 unités, qui correspondent à différentes périodes de dépôt.La première période correspond au développement d'une plateforme carbonatée d'âge Albien inférieur(?) à moyen, interrompu à l'Albien supérieur par la création tectonique d'un bassin rempli de turbidites d'âge Albien supérieur à Coniacien. La cartographie indique que ce "Bassin de Celica-Lancones s.s." comprend plusieurs unités tectoniques caractérisées par des séries crétacé supérieur différentes séparées par de failles importantes. Le secteur sud-est comprend principalement des dépôts volcano-clastiques, alors que le secteur nord-ouest montre des dépôts riches en quartz.Entre le Coniacien inférieur et le Campanien moyen, le "Bassin de Celica-Lancones s.s." d'avant-arc est déformé et érodé par le "phase tectonique péruvienne" d'âge Crétacé supérieur. La seconde période correspond au Crétacé terminal, quand un nouveau bassin d'avant-arc est créé, le Bassin de Paita-Yunguilla, beaucoup plus large et oblique que le Bassin de Celica-Lancones. Les sédiments du Bassin de Paita-Yunguilla présentent une succession comparable d'âge Campanien-Maastrichtien sur tout le bassin, et scellent la juxtaposition tectonique des séries antérieures. La présence d'épais dépôts conglomératiques ou bréchqiues d'âge Maastrichtien (inférieur ?) indique un nouvel événement tectonique.
