Marco tectónico deposicional, ambiente sedimentario y bioestratigrafía de la Formación Punta Ancón (Eoceno medio), acantilado del sector norte de Ballenita, provincia de Santa Elena

Abstract:

The Punta Ancón Formation corresponds to the Ancón Group (Middle Eocene). This study consists of defining the lithological composition, depositional, biostratigraphic and petrotectonic environment of Punta Ancón of the northern sector of Ballenita, Province of Santa Elena. Four outcrops, fifteen thin sections and eleven micropaleontological samples were described and analyzed, four ternary diagrams were applied for the classification and tectonic framework. Lithologically they are sandstones with intercalations of sandstone siltstone, tuffstone siltstone and arcillaillite; locally coal and plaster veinlets. Eleven sedimentary cycles were recognized, they show grain-growing and grain- decreasing sequences. The sedimentary environment is Backshore, Foreshore, Shoreface and Offshore. The middle Middle Eocene age is average by the nassellaria radiolaria Podocyrtis ampla and the environment is external platform due to the occurrence of spumellarios radiolarians (Haliomma sp., Periphaena duplus, Periphaena heliasteriscus, Stylophaera minor, Lithomesphilus coronatus Cenosphaera cristata and Lithocyclia ocellus). The sandstones are sublitarenites and the percentages of their components are: 80,9% quartz, 16,0% lithic fragments, 3,1% feldspars, 78,0% monocrystalline quartz, 18,4% total lithics, 45,4% quartz polycrystalline, 31,5% sedimentary lithics and 23,1% volcanic lithics. The provenance is Recycled Orogeny with a tendency to Subduction Complex and Collision. It is suggested that the components come from: monocrystalline quartz from the Andean continental margin, polycrystalline quartz from the Santa Elena Formation, volcanic lithics from the remaining Cayo island arch and sedimentary lithics from the Chongón Colonche mountain range.

Año de publicación:

2019

Keywords:

• CICLOS
• EPIPELÁGICO
• PODOCYRTIS
• SUBLITARENITA Y OROGENIA

Fuente:

rraae