Abstract

Information is furnished about the microfacies and microfossils of the Keating, Hachita, and Paradise formations which outcrop in the Sierra de Palomas, in northern Chihuahua.

Four microfacies of the Keating Formation are described.

1. Sparite without microfossils.

2. Sparite with crinoids.

3. Sparite with Earlandia.

4. Calcirudite with crinoids and fenestellids, Earlandia and “Nostocites”.

Based on the microfauna, microfacies 2, 3, and 4 are assigned to the Osagean.

Five microfacies are described for the Hachita Formation.

1. Sparry encrinite with bryozoans and Earlandia.

2. Sparry encrinite.

3. Micritic calcarenite with crinoids.

4. Sparry encrinite with ostracods and Earlandia.

5. Bryozoan and crinoidal calcarenite.

Based on the microfauna the Hachita is considered to be Osagean - Meramecian in age.

Seven microfacies are described for the Paradise Formation.

1. Quartzose oolitic limestone.

2. Calcirudite with bryozoans and crinoids.

3. Mottled quartzose limestone.

4. Limy sandstone.

5. Calcarenite with bryozoans, brachiopods, and the foraminifer Tetrataxis.

6. Bryozoan calcarenite.

7. Bryozoan and brachiopod calcarenite with Asteroarch-aediscus.

Based on microfauna, a Chesterian age is assigned to the Paradise.

All the microfossils present are typically marine inhabitants of shallow water on the continental shelf.