Río Quema Fm

Type Locality is at Río Quema on the Azuero Peninsula (Figure 141).

[Figure 141. Geologic Map of the West Cerro Quema area. Corral et al. (2011).]

Synonym: Río Quema Fm

The Río Quema Fm includes all sedimentary, volcaniclastic and extrusive volcanic units deposited in a fore-arc Basin, overlying both the Azuero Igneous Basement and locally the Azuero Proto-arc Gr. The following units have been distinguished in the Cerro Quema district:

A Lower Unit, made up of andesitic lava flows (0.20-2m thick) and well bedded crystal-rich sandstone to siltstone turbidites interbedded with hemipelagic thin limestone beds. W-SW paleocurrents were deduced from cross bedding, ripples and tool marks.

A Limestone Unit, corresponding to a 100-150m thick light grey biomicritic hemipelagic limestone which is interlayered with well bedded cherts, thinly bedded turbidites and ash layers. The presence of planktonic foraminifera (Globotruncana sp., Globotruncanita sp., and Globotruncanella sp.) indicates a Late Cretaceous age. A late Campanian–early Maastrichtian age. Similar limestone beds have also been found in the Torio and Güera rivers, following the southernmost E-W trend fault zone of the Azuero Peninsula.

An Upper Unit, which crops out both in the northern and southern part of the Río Quema section. The northern part is composed of volcaniclastic sediments interlayered with massive to laminar andesitic lava flows (1 to 3m thick), andesitic hyaloclastites (0.1 to 0.5m thick), and massive dacites overlain by dacite lava flows and dacitic and resedimented hyaloclastites (the latter up to 3m thick). However, in the southern part, this unit is characterized by volcaniclastic turbidites, crystal rich sandstones (up to 1m thick), siltstones and thin pelagic limestone beds (up to 0.2m). Whereas massive lava flows and extrusive rocks prevail in the northern part of the section, volcaniclastic turbidites are dominant in the southern region. W-SW paleocurrents are deduced from cross bedding. Basaltic-andesitic dikes intrude part of the series but are more common in the northern part of the study area. Corral et al. (2011)

Thickness: ~1,700 m

[Figure 140. Top - Simplified stratigraphic column for the Azuero Peninsula showing the interval assigned to the Río Quema Fm. Perelló et al. (2020) (Material reproduced with the permission of the editor). Bottom - Idealized stratigraphic section of the Río Quema Fm: A) Pillow basalts of the Azuero Igneous Basement at Río Joaquín. B) Volcaniclastic sediments of the Río Quema Fm lower unit at Río Quema. C) Hemipelagic limestones from the Río Quema Fm limestone unit south of Río Quema. D) Volcaniclastic and hemipelagic sediments crosscut by a basaltic-andesitic dike of the Río Quema Fm upper unit north of Río Quema. E) Fossiliferous calcarenite of the Tonosí Fm at Río Güerita. Corral et al. (2011).]

References: Corral et al. (2011); Perelló et al. (2020).