An Early Ordovician (Floian) Conodont Fauna from Peru.

GUTIÉRREZ-MARCO, J. C.; GUILLERMO LUIS ALBANESI; SARMIENTO, G. N.; CARLOTTO, V.

Geologica Acta

Lugar: Barcelona; Año: 2008 vol. 6 p. 147 - 160

1695-6133

Late Floian conodonts are recorded from a thin limestone lens intercalated in the lower part of the San José Formationat the Carcel Puncco section (Inambari River), Eastern Cordillera of Peru. The conodont associationincludes Gothodus costulatus LINDSTRÖM, Protopanderodus rectus (LINDSTRÖM), Drepanoistodus basiovalis(SERGEEVA), Drepanoistodus forceps (LINDSTRÖM), Drepanodus arcuatus PANDER, Trapezognathus diprion (LINDSTRÖM),Erraticodon patu COOPER, and Ansella cf. jemtlandica (LÖFGREN). This species association can beassigned to the upper part of the well-documented Oepikodus evae Zone. It is the northernmost conodont recordof late Floian age in South America. This study updates the preliminary data presented in 2001 from this fossillocality, and it has important consequences for the paleogeographic reconstruction of the Peruvian part of theCentral Andean Basin. In accordance with trilobites and brachiopods documented for the same strata, the conodontassociation represents a relatively cold-shallow-water platform environment. The record of late Floianconodonts towards the middle part of the San José Formation shows that the base of this unit in the studied sectionis considerably older than other sections of the distribution area, where its lowermost part is dated as earlyDarriwilian by the record of graptolites from the Undulograptus austrodentatus graptolite Zone. The diachronousinitiation of the marine sedimentation makes the lower part of the Carcel Puncco shales penecontemporaneouswith the volcanigenic rocks related with the Arequipa Massif, which transitionally underlie the San JoséFormation in other places of the Altiplano and the Eastern Cordillera of Peru.