The Mississippian of west-central New Mexico

Abstract

Mississippian rocks were studied in detail in the Ladron, Lemitar, and Magdalena Mountains, and Coyote Hills, of west-central New Mexico. The oldest Mississippian strata in this area belong to the Caloso Formation, which contains a small brachiopod fauna suggestive of a Kinderhookian or lower Osagian age. The Caloso Formation rests on a truncated igneous and metamorphic complex of Precambrian age. The base of the Caloso Formation consists of intergrading arkoses, sandstone, shales, and limestones. This is followed by about 30 ft of dark-gray fine-crystalline algal limestone. The Caloso Formation is overlain disconformably by the Kelly Formation, which varies from 0-70 ft in thickness and is light-tan to gray crinoidal limestone that contains a brachiopod and blastoid fauna of upper Osagian age. The Kelly Formation is overlain unconformable by the Sandia Formation of Pennsylvanian age in the Lemitar and Magdalena Mountains. In the Ladron Mountains the Kelly and Caloso Formations pinch out northward beneath the Sandia unconformity. The brachiopod, blastoid, and coral fauna of the Kelly and Caloso Formations are described and illustrated. This paper presents the results of faunal and stratigraphic studies of the Mississippian of west-central New Mexico. Exposures are limited largely to the Magdalena, Lemitar, and Ladron Mountains. From a regional viewpoint, the Mississippian strata of this region fill a gap between those of southern and those of northern New Mexico. The region covered in the present report is indicated. From a stratigraphic viewpoint, the Mississippian of west-central New Mexico has proved somewhat anomalous in relation to either southern or northern New Mexico. The two formations in the region under discussion, the Caloso and Kelly Formations, are not typically developed in any section containing either the Arroyo Penasco Formation of the north of the Caballero and Lake Valley Formations of the south. This report is concerned almost exclusively with the Mississippian strata present in the Magdalena, Lemitar, and Ladron Mountains. The Magdalena Mountains are a northward trending range with a maximum elevation of over 10,000 ft. They consist of tilted and faulted sedimentary and volcanic rocks on a Precambrian basement. The stratified rocks form the western slope of the range. The eastern side of the range consists mainly of Precambrian granite.

Proceedings of the 31st Forum on the Geology of Industrial Minerals--The Borderland Forum

“…Mississippian strata in northern and central New Mexico crop out as discontinuous remnants beneath an erosion surface of Late Mississippian and Early Pennsylvanian ages (Armstrong, 1955(Armstrong, , 1958. Some of the crinoidal calcarenites in the Sandia, Ladron, Magdalena, Nacimiento, and Sangre de Cristo Mountains appear to be relatively HC limestone, except for sparse to abundant chert lenses and nodules.…”

“…Reconnaisance sampling of high-calcium (HC) limestones in New Mexico has been reported by Siemers (1982), Jicha (1956), andKottlowski (1962). Numerous articles describe the limestone units in and near the state, such as Armstrong (1958) for west-central New Mexico, Mississippian and Pennsylvanian Systems in the state (Armstrong et al, 1979), Pennsylvanian units in southcentral New Mexico (Wilson, 1989), Pennsylvanian strata in southwestern New Mexico and southeastern Arizona (Kottlowski, 1960), Pennsylvanian section in the Big Hatchet Mountains (Thompson and Jacka, 1981), Paleozoic strata in the Big Hatchet Mountains (Zeller, 1965), Mississippian in southwestern New Mexico and southeastern Arizona (Armstrong, 1962(Armstrong, , 1978, Mississippian in the San Juan Mountains (Armstrong, 1978), Mississippian and Pennsylvanian rocks in the Sangre de Cristo Mountains (Sutherland, 1963), Pennsylvanian System in New Mexico (Bachman, 1975), Pennsylvanian and Wolfcampian rocks in southeastern New Mexico (Meyer, 1966), Paleozoic rocks in the Manzano Mountains (Myers, 1973), and Paleozoic strata in the Sacramento Mountains (Pray, 1961). Other shorter articles report on Paleozoic outcrops of individual quadrangles, and numerous reports detail the thick Permian strata in southeastern New Mexico in the Guadalupe Mountains; many of these Permian carbonate rocks are dolomite or dolomitic.…”

Geology, mineralogy, geochemistry, and geothermometry of Kelley Limestone jasperoids, Magdalena mining district, New Mexico

“…Mississippian-The Kelly Limestone is exposed in the Ladron, Lemitar, Magdalena, and Chupadera Mountains of west-central New Mexico (Armstrong, 1958). In the Magdalena Mountains, the Kelly Limestone was measured and sampled at the head of Jordan Canyon near the north end of the range.…”

“…In north-central Nevada, anomalous concentrations of gold appear to be concentrated mainly in the jasperoid parts of the mixed carbonate-jasperoid veins. Field studies for this report were done in 1988-1989 by Armstrong andin 1990-1992 by Renault and Armstrong. Renault studied the geochemistry and the silica-crystallite geothermometry of the jasperoids.…”

Preliminary report on the geology and mineral-resource potential of Torrance County, New Mexico

“…S m a l l p e g m a t i t e , a p l i t e , and s y e n i t e d i k e s i n t r u d e t h e p l u t o n . Formations (Armstrong, 1955(Armstrong, , 1958(Armstrong, , 1962 red and green shales and siltstones, and greenish-gray marine limestones (Myers, 1973(Myers, , 1982. Minor occurrences of copper mineralization are common in the upper beds of the Bursum Formation in the Scholle district.…”