Las Masas - Subibaja Fm (Miocene of Ecuador)

Where: Guayas, Ecuador (2.2° S, 80.2° W: paleocoordinates 3.4° S, 76.0° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Subibaja Formation, Early/Lower Miocene (23.0 - 16.0 Ma)

• Checklist from undifferentiated Subibaja Fm, which is of upper Early Miocene age, and underlies the Middle Miocene Progresso Fm. The thickness of the formation is 1800 ft at its type section. Age is approximately equivalent to the Burdigalian stage based on correlation with other S. and C. American faunas. It is regionally correlated with the Lower Zorritos (Peru) and Angostura (Ecuador) formations.

• formation-level stratigraphic resolution

Environment/lithology: coastal; poorly lithified, fine-grained, glauconitic, micaceous, pyritic, sandy, carbonaceous siltstone

• Shallow-water siliciclastic facies of typically tropical composition.
• Shale, siltstone, and fine-grained sandstone. Chiefly greenish-gray, friable to moderately indurated siltstone with shaly and sandy facies. Pyrite, glauconite, mica, and carbonaceous fragments common throughout.

Size class: macrofossils

Reposited in the PRI

• Fossil material derived from the International Ecuadorian Petroleum Company (subsidiary of Standard Oil Co.) and was collected by the author (then employed by oil company) during field exploration and drilling operations. All type and voucher material reposited in PRI collections.

Primary reference: J. G. Marks. 1951. Miocene stratigraphy and paleontology of Southwestern Ecuador. Bulletins of American Paleontology 33(139):1-448 [A. Miller/A. Hendy]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 61052: authorized by Austin Hendy, entered by Austin Hendy on 29.05.2006

Creative Commons license: CC BY (attribution)

Taxonomic list

• Exhaustive for gastropoda and bivalvia.
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