Azuero Arc Gr

Neogene

Paleogene

Cretaceous

Compiled by: Jacques LeBlanc (2021), Stratigraphic Lexicon: The Onshore Cenozoic Sedimentary Formations of The Republic of Panama. Biosis: Biological Systems, vol. 2/1, 1-173. https://doi.org/10.37819/biosis.002.01.0095(or via https://sites.google.com/site/leblancjacques).

Azuero Arc Gr

Period:

Cretaceous

Age Interval:

Cretaceous - Woodring (1960)

Province:
Tonosí & Azuero basin

Type Locality and Naming

Named by Hershey (1901) (Figure 052).

[Figure 1. The earliest known geological sketch map of the Central Portion of the Isthmus of Panama zoomimg in on the Azuero Peninsula. The map displays the formations known at that time and described by Hershey (1901).]

Synonym: Azuero Fm; Azuero Accretionary Complex

Lithology and Thickness

So far as now known, the oldest rock on the Isthmus of Panama is a green eruptive formation of unknown but immense thickness assumed to be late Jurassic or early Cretaceous. The whole formation is streaked by many exceedingly irregular veinlets of white quartz and calcite. Some veins contain a red mineral of the color of cinnabar, but the staining matter is probably iron oxide. Up the Torio River, the green rock sometimes assumes a schistose character, sometimes that of a non-laminated slaty rock, and again is clearly eruptive. It is possible that the complex may include highly metamorphic sedimentaries. Everywhere it is characterized by the veinlets of quartz. Cotains large irregular masses of structureless, hard, bright red quartz. See Figure 2&3 for more information.

[Figure 2. A zoom-in of the Azuero Gr (Azuero Accretionary Complex) which forms the SW edge of the Azuero Peninsula. It represents an accretionary complex composed of Cretaceous to Eocene accreted seamounts and oceanic islands. Modified from Buchs et al. (2008, 2011). Also in Barat (2013).]

[Figure 3. Tectonostratigraphic chart showing the igneous complexes exposed on the Azuero Peninsula and surrounding areas as well as the sedimentary formations overlapping them. The ages of all formations/complexes were measured either by 40 Ar/39 Ar or Paleontologic methods (Barat (2013) and Modified from Buchs et al. (2008)). Note that Buchs et al. (2011) and Barat (2013) now includes the Pesé Fm as part of the Tonosí Fm, and the Macaracas Fm as the equivalent of the Santiago Fm.]

Lithology Pattern:

Lava

Relationships and Distribution

Lower contact

Ocú Fm

Upper contact

Covachón Fm

Regional extent

On west side of Azuero Peninsula

GeoJSON

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Fossils

Age

Age Span:

Beginning stage:

Maastrichtian

Fraction up in beginning stage:

Beginning date (Ma):

72.17

Ending stage:

Lutetian

Fraction up in the ending stage:

Ending date (Ma):

48.07

Depositional setting

Depositional pattern:

Additional Information

References:

Hershey (1901)
Wilmarth (1938).
Woodring (1960). Poorly defined name for basement altered volcanic rocks. Late Jurassic or Early Cretaceous age was suggested.
Keroher et al. (1966).

Compiler:

Jacques LeBlanc (2021), Stratigraphic Lexicon: The Onshore Cenozoic Sedimentary Formations of The Republic of Panama. Biosis: Biological Systems, 2(1), 173 pp. https://doi.org/10.37819/biosis.002.01.0095 (or via https://sites.google.com/site/leblancjacques)