Permian stratigraphy in the Jarilla Mountains, Otero County, New Mexico
Spencer G. Lucas and Karl Krainer


We assign the limestone-dominated section of upper Paleozoic strata exposed in the northern Janina Mountains of Otero County, New Mexico, to the Pennsylvanian-Permian Panther Seep Formation and the Lower Permian Shalem Colony and Community Pit formations of the Hueco Group. Panther Seep strata (formerly referred to the Laborcita Formation by some workers) are mostly shale and thin beds of algal limestone that are extensively intruded by Cenozoic plutons and faulted, so previous thickness estimates of —500 m cannot be verified. Similarly, Hueco Group thicknesses of— 275 m in the Jarilla Mountains are overestimates, as the Hueco section here is only about 135 m thick. The Shalem Colony Formation is 68 m thick and consists of relatively thick beds of cherry, coarse-grained limestones and interbedded slopes of shale. The Community Pit Formation is at least 66 m thick (a complete section of the formation is not preserved in the Jarilla Mountains) and is composed of thin beds of lime wackestone and mudstone and intercalated shale slopes. Fusulinacean fossils indicate that the upper part of the Panther Seep Formation is earliest Wolfcampian in age, whereas the Shalem Colony Formation is of middle Wolfcampian age. Lithostratigraphic and biostratigraphic data support correlation of the Permian strata in the Jarilla Mountains to the much thicker Panther Seep-middle Hueco section in the southern San Andres Mountains, -- 50 km to the northwest.


  1. Lucas, Spencer G.; Krainer, Karl, 2002, Permian stratigraphy in the Jarilla Mountains, Otero County, New Mexico, in: Geology of White Sands, Lueth, Virgil W.; Giles, Katherine A.; Lucas, Spencer G.; Kues, Barry S.; Myers, Robert; Ulmer, Scholle, Dana S., New Mexico Geological Society, Guidebook, 53rd Field Conference, pp. 211-222.

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