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Lagunitas area (Eocene of Peru)

Where: Piura, Peru (4.7° S, 81.3° W: paleocoordinates 10.8° S, 107.5° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Cone Hill Formation (Chira Group), Priabonian (37.2 - 33.9 Ma)

• Olsson placed these fossils within the Mancora Formation (now considered Early Oligocene - Higley, 2004), but the area "Lagunitas" (Lagunitos on the map of Palacios, 1994) is mapped as undivided Chira-Verdun Groups by Palacios (1994). The older Salinas, Palegrada, and Pariņas Formations also occur in this area, but they are unlikely sources, indicating that this locality should be within the Chira Group (and likely within the Cone Hill Formation given the lithology and the replacement by gypsum). The Chira Group 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: marine; shale

• Elsewhere the Cone Hill contains seep deposits indicative of a deep-water environment, although the formation could span environments and this unit may be offshore shelf.
• Principally gypsiferous shales with thin seams of brown or gray sandstones and black pebbly conglomerates. Gypsum crystals are double-pointed, arrow-shaped bodies composed of gypsum [which are likely secondary]. Fossils rare and entirely replaced with gypsum.

Size class: macrofossils

Preservation: replaced with other

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 64544: authorized by Linda Ivany, entered by Linda Ivany on 10.09.2006

Creative Commons license: CC BY (attribution)