Late Cenozoic basalts of southwestern New Mexico
— Jerry M. Hoffer


Chemical analyses of 208 basaltic rocks from 13 occurrences in southern New Mexico show the existence of two differing basalt types. The group I basalt occurrences contain both alkalic and tholeiitic varieties with low SiO2 and high MgO and TiO2 concentrations. Group II basalts are 100% tholeiitic and contain high SiO2 and low MgO and TiO2 concentrations. Differences in Y, Zr, Rb, Sr and Ba concentrations also exist between the two groups. Spatially, the group I basalts occur in the center of the area and are flanked on the west and east by the group II basalts; this distribution is roughly parallel to the proposed boundaries of the Rio Grande rift.

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Recommended Citation:

  1. Hoffer, Jerry M., 1988, Late Cenozoic basalts of southwestern New Mexico, in: Cretaceous and Laramide tectonic evolution of southwestern New Mexico, Mack, G. H.; Lawton, T. F.; Lucas, S. G., New Mexico Geological Society, Guidebook, 39th Field Conference, pp. 119-122.

[see guidebook]