Circular 156 1978 Volcanoes and related basalts of Albuquerque Basin, New Mexico by V. C. Kelley and A. M. Kudo New Mexico Bureau of Mines & Mineral Resources A DIVISION OF NEW MEXICO INSTITUTE OF MINING & TECHNOLOGY Circular 156 New Mexico Bureau of Mines & Mineral Resources A DIVISION OF NEW MEXICO INSTITUTE OF MINING & TECHNOLOGY Volcanoes and related basalts of Albuquerque Basin, New Mexico by V. C. Kelley and A. M. Kudo SOCORRO 1978 ii Published by Authority of State of New Mexico, NMSA 1953 Sec. 63-1-4 Printed by University of New Mexico Printing Plant, September, 1978 Available from New Mexico Bureau of Mines & Mineral Resources, Socorro, NM 87801 Price $5.00 Preface This paper results from our mutual interest and current work on basalts of the Albuquerque Basin. Much new work is presented on the petrology and chemistry of the rocks (by Kudo) and on field relationships (by Kelley). Kudo's contribu- tions are a part of his study of basalts in New Mexico and other places in the Rockies. Kelley's contribution is an outgrowth of current study of the stratig- raphy, structure, and geomorphology of the Albuquerque Basin (Kelley, 1977). Parts of this circular appeared in "Guidebook to Albuquerque Basin of the Rio Grande rift" (Kelley and others, 1976). We acknowledge the assistance of: 1) John Husler, for chemical analyses of the rocks, 2) James A. Kasten, who mapped Cerro de Los Lunas and Tome Hill for his master's thesis under Kudo's direction, and 3) Jacques R. Renault, for suggestions on improving the manuscript. More detailed studies involving electron microprobe analysis and instrumental neutron activation analysis for trace elements in these volcanic rocks are underway (publication planned) by Kudo and his students. Samples collected for the present investigation are on file in the Department of Geology at the University of New Mexico. Part of the funding for thin sections and chemical analysis was provided by the New Mexico Energy Resources Board (grant ERB76-264) and U.S. Geological Survey (geothermal grant 14-08-001-G255). Kelley also received support from the University of New Mexico Research Allocations Committee and the New Mexico Bureau of Mines and Mineral Resources. Vincent C. Kelley Professor Emeritus Albert M. Kudo Albuquerque Associate Professor March 15, 1978 University of New Mexico Contents ABSTRACT 7 SCATTERED BASALT BODIES 26 Benavidez diatreme 26 INTRODUCTION 7 Mesita Negra 26 NORTH PART OF BASIN 8 Santo Domingo flow 26 San Felipe volcanoes 8 Borrego Mesa 26 Canjilon Hill 10 Placitas area 26 Albuquerque volcanoes 11 Trigo Canyon area 26 Cochiti dam area 27 Carpenter well 27 SOUTH PART OF BASIN 15 Dalies area 27 Isleta volcano 15 Well northwest of Los Lunas 27 Wind Mesa volcano 18 Well northwest of Albuquerque volcanoes 27 Cat Hills volcanoes 18 Cat Mesa flow 20 SUMMARY 27 Lucero Mesa 20 Occurrence and succession 27 Mohinas and Hidden Mountains 21 Petrology 28 Los Lunas volcano 21 REFERENCES 31 Tome Hill 23 Black Butte 24 POCKET (sheets 1 and 2) Tables 1—Chemical composition San Felipe basalts 10 2— 10—Modal compositions of selected flows Cat Hills Chemical composition Canjilon basalts 11 3— volcanoes 20 Chemical composition Albuquerque basalts 14 4— 11—Chemical composition Lucero Mesa basalt 21 Modal compositions of selected flows Albuquerque 12—Chemical composition Los Lunas andesite 23 volcano 14 13—Modal compositions of selected flows Los Lunas 5—Chemical composition of Isleta basalts 17 volcano 23 6—Modal compositions of selected flows Isleta volcano 17 14—Chemical composition Tome andesite 24 15—Modal 7—Chemical composition Wind Mesa basaltic andesite 18 compositions of selected flows Tome Hill 24 16— 8—Modal composition of selected flows Wind Mesa Chemical composition Black Butte andesite and volcano 18 rhyolite 25 9—Chemical composition Cat Hills basalt 20 Figures 1—Location of volcanic features 6 18—Airview of Cat Hills and Wind Mesa 19 2—Map of San Felipe field sheet 1 19—View of largest cone Cat Hills 19 3—Airview of step-faulted San Felipe flows 8 20—Cross section from Cat Mesa to Cat Hills 20 4—View of San Felipe flow 1 9 21—Map of Mohinas Mountain sheet 2 5—Plot of alkali-silica for basalts and andesites of 22—Airview of Los Lunas volcano 22 Albuquerque Basin 10 23—Map of Los Lunas volcano sheet 2 6—Map of Canjilon Hill sheet 1 24—Cross section of Los Lunas volcano 22 7—Vertical airphoto Canjilon Hill 11 25—Airview of Tome Hill 24 8—View of Octopus plug Canjilon Hill 11 26—Map of Tome Hill sheet 2 9—Vertical airphoto of Octopus plug Canjilon Hill 12 27—Airview of Black Butte 25 10—Map of Albuquerque field sheet 1 28—Map of Black Butte sheet 2 11—View of radial dike Vulcan cone 13 29—View of Benavidez diatreme 26 12—Map of Isleta volcano sheet 1 30—AMF diagram for basalts and andesites of Albuquerque 13—View of tuff breccia Isleta volcano 15 Basin 28 14—Airview of Isleta Pueblo 16 31—Normative plots on plagioclase-olivine-quartz face of 15—View of collapse surface Isleta volcano 16 basalt tetrahedron 28 16—Cross section of Isleta volcano 17 32—Normative plots on diopside-plagioclase-hypersthene 17—Map of Wind Mesa, Cat Hills, and Cat Mesa she et 1 face of basalt tetrahedron 28 6 7 Abstract During the Pliocene-Pleistocene, numerous eruptions (alkali basaltic, olivine tholeiitic, and minor andesitic) occurred within the Albuquerque Basin of the Rio Grande rift. The principal volcanic fields—San Felipe, Albuquerque, and the Cat Hills-Wind Mesa group— appear to trend about N. 15 ° E., roughly paralleling the axis of the basin. To the west of these fields is a lesser alignment of volcanoes that includes Benevidez diatreme, Mesita Negra, and Mohinas Mountain. Volcanism at Los Lunas, Tome Hill, and Black Butte, all east of the main alignment, is andesitic. Quaternary erosion in the inner valley has exposed a variety of formations and volcanic features. At least 5 or 6 flows and explosive phases are found in many of the volcanic centers. Usually the earliest eruptions are low in viscosity and form widespread fissures. Later eruptions are thicker, are less expansive, have greater surface irregularity, and are restricted to central vents. Many of the eruptions culminate with the formation of cinder cones. The olivine tholeiite at the Albuquerque volcanoes becomes increasingly hypersthene normative with time and has a differentiation trend consistent with the mode of the basalts containing olivine and plagioclase phenocrysts. The olivine tholeiite could have differentiated at depths less than 24 km by settling out of olivine and plagioclase. The alkali basalts at Cat Hills and Isleta must have differentiated at pressures in excess of 8 kb. Modally, the basalts contain olivine and plagioclase phenocrysts with minor augite. The generation of these basalts may be related to the degree of partial melting in the mantle at pressures well in excess of 8 kb. The hypersthene normative lavas that erupted first may have come from mantle partially melted by more than 20 percent whereas the later nepheline normative eruptions tapped mantle less melted. The origin of the andesites in the Albuquerque Basin is uncertain; a shallow origin under hydrous conditions is possible. Introduction The Albuquerque Basin (Bryan, 1938, p. 213) is part Six principal areas dominate the picture, in order of of the great Rio Grande depression that extends from size: San Felipe, Cat Hills, Albuquerque, Wind Mesa, southern Colorado south through New Mexico into Isleta, and Los Lunas. In an effort to determine trends northern Mexico. The basin is one of a number of and similarities of eruption and petrology, several flow north-trending intermontane grabens that are roughly units have been mapped, sampled, and studied in each axial to the eastern Rockies or Colorado and New Mex- area. Although the rocks are predominantly olivine ico Rockies (Eardley, 1962, p. 399). In the present basalt, some progression in petrography and composi- report the area of the Albuquerque Basin also includes tion is evident through the first to last flow sequences. the Santo Domingo Basin (Kelley, 1952, p. 92) and ex- At each center, the early flows (first two or three) are tends from the La Bajada escarpment on the north to generally thinner, smoother, or more regular in thick- the Socorro constriction near the southern ends of the ness. The later ones are less expansive, thicker, more ir- flanking Ladron and Los Pinos Mountains. The area is regular, and display more bulging or mounding of their about 100 mi long (north-south) and 25-30 mi wide surfaces. Few or no ropy or pahoehoe types are present; (west-east). likewise, the flows are not blocky or spinose on their Subsidence and filling by continental sediments oc- surfaces. For the most part the flows are intermediate curred in late Miocene and Pliocene. Numerous basaltic between as and pahoehoe types. The best preserved sur- eruptions accompanied and followed sedimentation, faces of flows are those in the southern part of the main especially in Pliocene and early Pleistocene. However, Cat Hills field where, in successive flow units, slightly such eruptions are more numerous outside the Rio different surface patterns appear to result from increas- Grande depression than in it. Also, such eruptions are ing viscosity. more numerous in the parts of the Rio Grande depres- Numerous cinder cones occur in the Cat Hills, Wind sion north of the Albuquerque Basin. Mesa, San Felipe, and Albuquerque fields. Those of Cat Approximately a dozen basaltic centers and areas Hills are outstanding in their development and composed of both alkali basalts and olivine tholeiites preservation.