Chagres Formation

{{Infobox rockunit

| name = Chagres Formation

| image =

| caption =

| type = Formation

| age = Tortonian-Messinian
(Clarendonian-Hemphillian)
~{{fossil range|11.6|5.3}}

| period = Messinian

| prilithology = Sandstone

| otherlithology = Siltstone

| namedfor = Chagres River

| namedby = MacDonald

| year_ts = 1919

| region = Colón Province

| country = Panama

| coordinates = {{coord|9.2|N|80.3|W|display=inline,title}}

| paleocoordinates = {{coord|9.0|N|79.4|W|display=inline}}

| unitof =

| subunits = Río Indio & Toro Limestone Members

| underlies = alluvium

| overlies = Gatún Formation

| thickness = uncertain

| extent = Panama Basin

| area =

| map = {{Location map+ | Panama

| relief = 1

| width = 250

| float = center

| places =

{{Location map~ | Panama

| lat_deg = 9.2

| lon_deg = -80.3

| mark = Yellow pog.svg

| marksize = 12

}}

| map_caption =

}}

The Chagres Formation (Tc)Geologic Map, 1980 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 {{convert|45|km|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.Woodring, 1957, p.47

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.

Fossil content

Various fossils have been found in the Chagres Formation:[https://paleobiodb.org/classic/displayCollResults?collection_no=160781 Pina] at Fossilworks.org

= Fish =

Alopias superciliosus
Benthosema pluridensSchwarzhans & Aguilera, 2013
Carcharhinus brachyurus
Carcharhinus cionei
Carcharhinus obscurus
Carcharhinus plumbeus
Carcharhinus signatus
Carcharodon plicatilis
Centrophorus granulosus
Cynoscion prolixusAguilera et al., 2016
Dalatias licha
Diaphus barrigonensis, D. rodriguezi
Galeocerdo cuvier
Galeorhinus galeus
Hemipristis serra
Heptranchias perlo
Heterodontus sp.
Isistius sp.
Lampadena scapha
Lepidophanes inflectus
Megalodon
Mustelus sp.
Myctophum arcanum, M. degraciai
Myliobatis sp.
Premontreia sp.
Pristiophorus sp.
Pseudocarcharias kamoharai
Rhizoprionodon sp.
Sphyrna lewini
Squalus sp.
Squatina sp.
Trigonognathus sp.

= Mammals =

Isthminia panamensis[https://paleobiodb.org/classic/displayCollResults?collection_no=172931 STRI 650009] at Fossilworks.orgPyenson et al., 2015
Nanokogia isthmiaVélez Juarbe et al., 2015

= Invertebrates =

Fusiturricula fenimoreiHendy et al., 2008

References

= Bibliography =

{{citation |last1=Aguilera |first1=Órangel A. |last2=Schwarzhans |first2=Werner |last3=Béarez |first3=Philippe |year=2016 |title=Otoliths of the Sciaenidae from the Neogene of tropical America |url=https://www.researchgate.net/publication/301301677 |journal=Palaeo Ichthyologica |volume=14 |pages=7–90 |accessdate=2019-02-09}}
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
{{citation|author1-link=Nicholas Pyenson |last1=Pyenson |first1=Nicholas D. |last2=Vélez Juarbe |first2=Jorge |last3=Gutstein |first3=Carolina S. |last4=Little |first4=Holly |last5=Vigil |first5=Dioselina |last6=O'Dea |first6=Aaron |year=2015 |title=Isthminia panamensis, a new fossil inioid (Mammalia, Cetacea) from the Chagres Formation of Panama and the evolution of 'river dolphins' in the Americas |url=https://peerj.com/articles/1227.pdf |journal=PeerJ |volume=3 |pages=e1227 |doi=10.7717/peerj.1227 |doi-access=free |pmid=26355720 |pmc=4562255 |accessdate=2019-02-09}}
{{citation |last1=Schwarzhans |first1=Werner |last2=Aguilera |first2=Órangel |year=2013 |title=Otoliths of the Myctophidae from the Neogene of tropical America |url=http://www.pfeil-verlag.de/07pala/e4_66.php |journal=Palaeo Ichthyologica |volume=13 |pages=83–150 |accessdate=2019-02-09}}
{{citation |last1=Stewart |first1=R.H. |last2=Stewart |first2=J.L. |last3=Woodring |first3=W.P. |year=1980 |title=Geologic Map of the Panama Canal and Vicinity |url=https://pubs.usgs.gov/pp/0306f/plate-1.pdf |publisher=USGS |pages=1 |accessdate=2019-02-09}}
{{citation |last1=Vélez Juarbe |first1=Jorge |last2=Wood |first2=Aaron R. |last3=De Gracia |first3=Carlos |last4=Hendy |first4=Austin J.W. |year=2015 |title=Evolutionary Patterns among Living and Fossil Kogiid Sperm Whales: Evidence from the Neogene of Central America |journal=PLoS ONE |volume=10 |issue=4 |pages=e0123909 |doi=10.1371/journal.pone.0123909 |doi-access=free |pmid=25923213 |pmc=4414568 |bibcode=2015PLoSO..1023909V }}
{{citation |last=Woodring |first=W.P |year=1957 |title=Geology and Paleontology of Canal Zone and Adjoining Parts of Panama - 306A Geology and description of Tertiary mollusks (Gastropods: Trochidae to Turritellidae) |url=https://pubs.usgs.gov/pp/0306a/report.pdf |publisher=USGS |pages=1–186 |accessdate=2019-02-09}}