Mirador Conglomerates near Tamarindo (Eocene of Peru)

Where: Peru (4.9° S, 81.0° W: paleocoordinates 7.4° S, 73.8° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Mirador Formation (Chira Group), Priabonian (38.0 - 33.9 Ma)

• Olsson assigned the Mirador Conglomerates to the Mancora Formation (now considered Early Oligocene - Higley, 2004), but Palacios (1994) stated that the Mirador Conglomerate is the middle unit of the Chira Formation, or the middle formation of the Chira Group. The entire area around Tamarindo is mapped as Chira Formation/Group by Palacios (1994), indicating that this locality should be within the Chira Group. The Chira contains diatoms indicative of a latest Eocene age (Marty et al., 1988; Koizumi, 1992), regional Upper Eocene planktonic foraminifera as Hantkenina primitiva, Globigerina mexicana, Globigerina topilensis, and Guembelina venezuelana (Weiss, 1955), and radiolarians of the C. azyx (RP17) or C. bandyca (RP18) zones (Marty, 1989) - all of which indicate a Priabonian age.

• group of beds-level stratigraphic resolution

Environment/lithology: coastal; coarse-grained sandstone

• Typically described as a shallow-marine facies, but precise environment is uncertain.
• Sandy zones that accompany the Mirador conglomerates. in Olsson. "Coarse-grained whitish sandstones with conglomerate horizons" according to Palacios (1994).

Size class: macrofossils

Primary reference: A. A. Olsson. 1931. Contributions to the Tertiary Paleontology of Northern Peru: Part 4, The Peruvian Oligocene. Bulletins of American Paleontology 17(63) [L. Ivany/L. Ivany]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 55440: authorized by Linda Ivany, entered by Linda Ivany on 23.10.2005

Creative Commons license: CC BY (attribution)

Taxonomic list

Gastropoda
 Cerithioidea - Potamididae
Hannatoma emendorferi n. sp. Olsson 1931 horn snail
 Architaenioglossa - Ampullinidae
Ampullinopsis spenceri n. sp. Cooke 1919 snail
Ampullina bravoensis n. sp. Olsson 1931 snail
Cephalopoda
 Nautilida - Aturiidae
Aturia peruviana Olsson 1928
Aturia alabamensis var. peruviana