La Chilca Formation

La Chilca Formation (Spanish: Formación La Chilca) is a geological formation that crops out in the Precordillera of San Juan Province, Argentina. Rocks of the formation are mostly shale and sandstone that deposited during the Ordovician and Silurian periods.^[1] The formation contains a high diversity of graptolite fossils.^[1][2] Graptolite fossil taxa found include:^[1]

• Monograptus priodon
• Retiolites geinitzianus
• Stimulograptus sedgwickii
• Metaclimacograptus asejradi
• Pseudoplegmatograptus reticulatus
• Talacastograptus leanzai
• Coronograptus
• Pristiograptus
• Stimulograptus
• Pristiograptus

References

1. Lopez, Fernando Enrique; Kaufmann, Cintia (2023). "New insights on the Silurian graptolite biostratigraphy of the La Chilca Formation, Poblete Norte section, Central Precordillera of San Juan, Argentina: faunal replacement and paleoenvironmental implications". Andean Geology. 50 (2): 201. doi:10.5027/andgeov50n2-3617.
2. Serra, F.; Feltes, N.A.; Mango, M.J.; Henderson, M.A.; Albanesi, G.L.; Ortega, G.D.C. (2020). "Darriwilian (Middle ordovician) conodonts and graptolites from the cerro la chilca section, central precordillera, Argentina". Andean Geology. 47 (1): 125–143. doi:10.5027/andgeoV47n1-3229.