Bioestratigrafía, ambiente sedimentario y tectónica deposicional de las areniscas de la formación Punta Ancón (eoceno medio), Acantilado de Ballenita, Provincia de Santa Elena
Fecha
2019
Título de la revista
ISSN de la revista
Título del volumen
Editor
Facultad de Ciencias Naturales. Universidad de Guayaquil
Resumen
La Formación Punta Ancón (Eoceno Medio) sobreyace a la Formación Seca (Eoceno
medio) y no son reservorio productivo de petróleo. Este estudio tiene como objetivo
definir el ambiente sedimentario de depositación, edad y marco tectónico de
depositación de las rocas de la Formación Punta Ancón en el acantilado de Ballenita,
Provincia de Santa Elena. Se analizaron 15 láminas de arenisca y ocho muestras
bioestratigrafícas, se utilizaron diagramas de procedencia y clasificación para las
areniscas. Se describieron tres afloramientos que consisten de areniscas, arcillolitas
limosas, limolitas tobáceas, limolitas y areniscas microconglomeráticas. Se
evidenciaron ocho ciclos sedimentarios y el ambiente deposicional es Supralitoral
(Backshore), Litoral (Foreshore), Sublitoral (Shoreface) y Costa afuera (Offshore).
La edad es Eoceno medio temprano a Eoceno medio tardío por la presencia de
radiolarios spumellarios Lithocyclia ocellus Ehrenberg y el paleoambiente es marino
de poca profundidad por la ocurrencia de los radiolarios spumellarios Lithocyclia
ocellus Ehrenberg y Haliomma spp. Esta Formación en los acantilados de Ballenita
fue asignada erróneamente a la Formación Zapotal del Oligoceno. Las areniscas de la
Formación Punta Ancón en el acantilado de Ballenita son subarcosa, lítica
feldespática, sublitarenita y litarenita; y el ambiente tectónico es Orógeno Reciclado,
Orógeno de Arco, Orógeno de Colisión y Complejo de Subducción. Desde el
Paleoceno hasta el Eoceno Temprano, existió una deformación tectónica de flujo
detrítico silícico y roturas sedimentarias, lo que produjo la colisión del sur de la costa
ecuatoriana con el margen continental andino. Por lo tanto, el cuarzo monocristalino
proviene del Margen continental andino, cuarzo policristalino de la Formación Santa
Elena, líticos volcánicos del Arco remanente Cayo y líticos sedimentarios de la
Cordillera Chongón Colonche.
The Punta Ancón Formation (Middle Eocene) overlies the Seca Formation (Middle Eocene) and is not a productive oil reservoir. The objective of this study is to define the sedimentary environment of deposition, age and the tectonic setting of the rocks of the Punta Ancón Formation in the cliff Ballenita, Province of Santa Elena. Fifteen thin sections of sandstones and eight biostratigraphic samples were analyzed; provenance and classification diagrams were used for the sandstones. Three outcrops were described, consisting of sandstones, silty claystones, tuffaceous siltstones, siltstones, and microconglomeratic sandstones. Eight sedimentary cycles were evidenced and the depositional environment is Backshore, Foreshore, Shoreface and Offshore. The age is early Middle Eocene to late Middle Eocene because of the presence of radiolarian spumellarios Lithocyclia ocellus Ehrenberg; and the paleoenvironment is shallow marine because of radiolarian spumellarios Lithocyclia ocellus Ehrenberg and Haliomma spp. This formation in the Ballenita cliffs was erroneously assigned to the Oligocene Zapotal Formation. The sandstones of the Punta Ancón Formation on the cliff of Ballenita are subarkose, lithic feldspathic, sublitharenite and litharenite; and the tectonic provenance is Orogenic Recycled, Orgenous Arc, Oxygen Collision and Subduction Complex. From the Paleocene to the Early Eocene, there was a tectonic deformation of siliceous detrital flow and sedimentary breaks, which produced the collision of the southern Ecuadorian coast with the Andean continental margin. Therefore, the monocrystalline quartz comes from the Andean continental margin, the polycrystalline quartz from the Santa Elena Formation, volcanic lithic from the Cayo arc remnants and sedimentary lithics from the Chongón Colonche Mountain Range.
The Punta Ancón Formation (Middle Eocene) overlies the Seca Formation (Middle Eocene) and is not a productive oil reservoir. The objective of this study is to define the sedimentary environment of deposition, age and the tectonic setting of the rocks of the Punta Ancón Formation in the cliff Ballenita, Province of Santa Elena. Fifteen thin sections of sandstones and eight biostratigraphic samples were analyzed; provenance and classification diagrams were used for the sandstones. Three outcrops were described, consisting of sandstones, silty claystones, tuffaceous siltstones, siltstones, and microconglomeratic sandstones. Eight sedimentary cycles were evidenced and the depositional environment is Backshore, Foreshore, Shoreface and Offshore. The age is early Middle Eocene to late Middle Eocene because of the presence of radiolarian spumellarios Lithocyclia ocellus Ehrenberg; and the paleoenvironment is shallow marine because of radiolarian spumellarios Lithocyclia ocellus Ehrenberg and Haliomma spp. This formation in the Ballenita cliffs was erroneously assigned to the Oligocene Zapotal Formation. The sandstones of the Punta Ancón Formation on the cliff of Ballenita are subarkose, lithic feldspathic, sublitharenite and litharenite; and the tectonic provenance is Orogenic Recycled, Orgenous Arc, Oxygen Collision and Subduction Complex. From the Paleocene to the Early Eocene, there was a tectonic deformation of siliceous detrital flow and sedimentary breaks, which produced the collision of the southern Ecuadorian coast with the Andean continental margin. Therefore, the monocrystalline quartz comes from the Andean continental margin, the polycrystalline quartz from the Santa Elena Formation, volcanic lithic from the Cayo arc remnants and sedimentary lithics from the Chongón Colonche Mountain Range.
Descripción
PDF
Palabras clave
ARENISCAS, AMBIENTE MARINO, AMBIENTE TECTÓNICO, CICLOS DEPOSICIONALES, AMBIENTES DEPOSICIONAL