Iscayachi Formation

Iscayachi Formation
Stratigraphic range: Tremadocian ~488–479  Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Thickness	1,000 m (3,300 ft)
Lithology
Primary	Shale, sandstone
Location
Coordinates	22°00′S65°00′W / 22.0°S 65.0°W / -22.0; -65.0
Approximate paleocoordinates	46°18′S128°18′W / 46.3°S 128.3°W / -46.3; -128.3
Region	Potosí & Tarija Departments
Country	Bolivia
Type section
Named for	Iscayachi
Iscayachi Formation (Bolivia)

The Iscayachi Formation, in older literature also referred to as Guanacuno Formation, is an extensive Tremadocian geologic formation of western and southern Bolivia. The shales and sandstones were deposited in a shallow marine to pro-delta environment. ^{[1] [2] [3] [4] [5]} The formation reaches a thickness of 1,000 metres (3,300 ft). ^[1]

Fossil content

The formation has provided the following fossils:

• Akoldinoidia sinuosa ^[6]
• Altiplanelaspis palquiensis ^[7]
• Angelina hyeronimi , A. punctalineata ^[8]
• Asaphellus communis , A. riojanas
• Deltacare prosops
• Conophrys erquensis ^[9]
• Golasaphus palquiensis ^[7]
• Jujuyaspis keideli
• Kainella andina , ^[6] K. meridionalis
• Kvania lariensis
• Leptoplastides mariana
• Macrocystella bavarica
• Micragnostus hoeki
• Onychopyge branisai ^[10]
• Parabolinella argentinensis , P. boliviana ^[11]
• Pharostomina alvarezi , P. trapezoidalis ^[12]
• Rhabdinopora flabelliformis
• Rhadinopleura incaica ^[10]
• Rossaspis rossi
• Saltaspis steinmanni ^[11]
• Shumardia erquensis
• Leptoplastides cf. granulosa ^[13]
• Altiplanelaspis sp.
• Araiopleura sp.
• Broeggeria sp.
• Ctenodonta sp.
• Dictyonema sp.
• Koldinioidia sp.
• Leiostegium sp.
• Nanorthis sp.
• Onychopyge sp.
• Palquiella sp.
• Parabolina sp.
• Saltaspis sp.
• Sphaerocare sp.
• Trilobitarum sp.
• Tropidodiscus sp.

See also

• List of fossiliferous stratigraphic units in Bolivia

References

1. Suárez Riglos et al., 2018, p.37
2. Quebrada de Rota at Fossilworks.org
3. Palqui at Fossilworks.org
4. Tres Cruces at Fossilworks.org
5. Iscayachi Formation at Fossilworks.org
6. Suárez Riglos et al., 2018, p.52
7. Suárez Riglos et al., 2018, p.43
8. Suárez Riglos et al., 2018, p.48
9. Suárez Riglos et al., 2018, p.53
10. Suárez Riglos et al., 2018, p.45
11. Suárez Riglos et al., 2018, p.51
12. Suárez Riglos et al., 2018, p.42
13. Suárez Riglos et al., 2018, p.47

Bibliography

• Suárez Riglos, Mario; Dalenz Farjat, Alejandra; Pérez Leyton, Miguel Ángel (2018), Fósiles y Facies de Bolivia (PDF), Sincronía Diseño & Publicidad, Santa Cruz de la Sierra, pp. 1–146, ISBN   978-99974-79-68-6 , retrieved 2019-03-03

Further reading

• J. L. Benedetto. 2007. New Upper Cambrian-Tremadoc rhynchonelliformean brachiopods from northwestern Argentina: evolutionary trends and early diversification of plectorthoideans in the Andean Gondwana. Journal of Paleontology 81(2):261-285
• A. Pribyl and J. Vanek. 1980. Ordovician trilobites of Bolivia. Rozpravy Ceskoslovenske Akademie Ved. Rada Matematickych a Prirodnich Ved. Academia Praha, Prague, Czechoslovakia 90(2):1-90
• R. Suárez Soruco. 1976. El sistema ordovícico en Bolivia. Revista Tecnica YPF Bolivia 5(2):111-123