Chagres Formation

The Chagres Formation (Tc)[1] is a geologic formation in the Colón Province of central Panama. The sandstones and siltstones were deposited in a shallow marine environment and preserve fossils dating back to the Middle to Late Miocene (Tortonian to Messinian, Clarendonian to Hemphillian in the NALMA classification) period.

Chagres Formation
Stratigraphic range: Tortonian-Messinian
(Clarendonian-Hemphillian)
~11.6–5.3 Ma
TypeFormation
Sub-unitsRío Indio & Toro Limestone Members
Underliesalluvium
OverliesGatún Formation
Thicknessuncertain
Lithology
PrimarySandstone
OtherSiltstone
Location
Coordinates9.2°N 80.3°W / 9.2; -80.3
Approximate paleocoordinates9.0°N 79.4°W / 9.0; -79.4
RegionColón Province
Country Panama
ExtentPanama Basin
Type section
Named forChagres River
Named byMacDonald
Year defined1919
Chagres Formation (Panama)

Description

The Chagres Formation is exposed in the northern part of the Panama Canal Zone. The formation overlies and partly overlaps the Gatún Formation. The outcrop area lies entirely west of the Panama Canal, extending from the Canal Zone southwestward along the Caribbean coast, about 45 kilometres (28 mi) southwest of Colón. Calcareous strata at the base of the formation throughout most of the outcrop area in the Canal Zone constitute the Toro limestone member.[2]

The name Chagres Sandstone was proposed by MacDonald in 1919 for the sandstone forming the hills that overlook the coast from Toro Point to the mouth of the Chagres River. The sandstone is so massive that estimates of thickness are uncertain.[2]

Fossil content

Various fossils have been found in the Chagres Formation:[3]

Fish

Mammals

Invertebrates
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See also
  • List of fossiliferous stratigraphic units in Panama

References
  1. Geologic Map, 1980
  2. Woodring, 1957, p.47
  3. Pina at Fossilworks.org
  4. Schwarzhans & Aguilera, 2013
  5. Aguilera et al., 2016
  6. STRI 650009 at Fossilworks.org
  7. Pyenson et al., 2015
  8. Vélez Juarbe et al., 2015
  9. Hendy et al., 2008

Bibliography
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