Chagres Formation
Chagres Formation Stratigraphic range: Tortonian-Messinian (Clarendonian-Hemphillian) ~ | |
---|---|
Type | Formation |
Sub-units | Río Indio & Toro Limestone Members |
Underlies | alluvium |
Overlies | Gatún Formation |
Thickness | uncertain |
Lithology | |
Primary | Sandstone |
Other | Siltstone |
Location | |
Coordinates | 9°12′N 80°18′W / 9.2°N 80.3°WCoordinates: 9°12′N 80°18′W / 9.2°N 80.3°W |
Approximate paleocoordinates | 9°00′N 79°24′W / 9.0°N 79.4°W |
Region | Colón Province |
Country | Panama |
Extent | |
Type section | |
Named for | Chagres River |
Named by | MacDonald |
Year defined | 1919 |
Chagres Formation (Panama) |
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.
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[]
- Alopias superciliosus
- [4]
- Carcharhinus brachyurus
- Carcharhinus obscurus
- Carcharhinus plumbeus
- Carcharhinus signatus
- Centrophorus granulosus
- [5]
- Dalatias licha
- , [4]
- Galeocerdo cuvier
- Galeorhinus galeus
- Hemipristis serra
- Heptranchias perlo
- Heterodontus sp.
- Isistius sp.
- [4]
- [4]
- Megalodon
- Mustelus sp.
- , [4]
- Myliobatis sp.
- Pristiophorus sp.
- Pseudocarcharias kamoharai
- Rhizoprionodon sp.
- Sphyrna lewini
- Squalus sp.
- Squatina sp.
- Trigonognathus sp.
Mammals[]
- Isthminia panamensis[6][7]
- Nanokogia isthmia[8]
Invertebrates[]
See also[]
- List of fossiliferous stratigraphic units in Panama
References[]
Bibliography[]
- Otoliths of the Sciaenidae from the Neogene of tropical America. 14. 7–90. Accessed 2019-02-09. ; , and . 2016.
- A. J. W. Hendy, D. P. Buick, K. V. Bulinski, C. A. Ferguson, and A. I. Miller. 2008. Unpublished census data from Atlantic coastal plain and circum-Caribbean Neogene assemblages and taxonomic opinions
- Isthminia panamensis, a new fossil inioid (Mammalia, Cetacea) from the Chagres Formation of Panama and the evolution of ‘river dolphins’ in the Americas. PeerJ 3. e1227. Accessed 2019-02-09. ; ; ; ; , and . 2015.
- Otoliths of the Myctophidae from the Neogene of tropical America. 13. 83–150. Accessed 2019-02-09. , and . 2013.
- Geologic Map of the Panama Canal and Vicinity, 1. USGS. Accessed 2019-02-09. ; , and . 1980.
- Evolutionary Patterns among Living and Fossil Kogiid Sperm Whales: Evidence from the Neogene of Central America. PLoS ONE 10. e0123909. Accessed 2019-02-09. ; ; , and . 2015.
- Geology and Paleontology of Canal Zone and Adjoining Parts of Panama - 306A Geology and description of Tertiary mollusks (Gastropods: Trochidae to Turritellidae), 1–186. USGS. Accessed 2019-02-09. . 1957.
- Geologic formations of Panama
- Neogene Panama
- Messinian
- Tortonian
- Clarendonian
- Hemphillian
- Sandstone formations
- Siltstone formations
- Shallow marine deposits
- Paleontology in Panama
- Colón Province
- Panama Canal Zone