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Tracing Igneous Rocks into the High Plains

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A great exposure of a mid-Cenozoic igneous dike intruding Cretaceous sedimentary strata near I-25 in northeastern New Mexico with Luke Romero, Jennifer Lindline, and Mike Petronis of the Natural Resources Management Department at New Mexico Highlands University for scale.
(click for a larger version)
Snir Attia

— April 17, 2023

Over several weeks in November, I have been visiting a set of dikes, sills, and plugs that outcrop across eastern New Mexico. These igneous rocks represent the easternmost magmatism related to the past 350 million years of tectonic activity responsible for shaping what is now western North America! Although quite small and widely separated, these minor occurrences stretch from the New Mexico-Texas state line near Carlsbad Caverns to Raton (see map). Unlike the more prominent igneous occurrences closer to the Rio Grande, these rocks have received little attention from geologists. This belt of rocks presents a unique opportunity for basic research as well as a great chance for me to discover the beauty of eastern New Mexico and work with colleagues across the state!

Studying these features will help us to reconstruct the landscape development of New Mexico in between the building of the Rocky Mountains and the formation of the widespread Ogallala Caprock. These rocks are also key to our understanding of the tectonic significance of mid-Cenozoic magmatism in the southwestern United States.

— Snir Attia, Field Geologist, NMBGMR

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This map highlights the igneous rocks that make up the Cordilleran magmatic periphery of New Mexico.
(click for a larger version)
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Sunset over the Guadalupe Mountains from the Black River Valley, where several dikes are exposed along U.S. Highway 62.
(click for a larger version)
Snir Attia