Recent Vertical Crustal Movements from Leveling Observations in the Vicinity of the Rio Grande Rift
- Robert E. Riecker
Published Online: 21 MAR 2013
Copyright © 1979 by the American Geophysical Union.
Rio Grande Rift: Tectonics and Magmatism
How to Cite
Reilinger, R.E., Brown, L.D., Oliver, J.E. and York, J.E. (1979) Recent Vertical Crustal Movements from Leveling Observations in the Vicinity of the Rio Grande Rift, in Rio Grande Rift: Tectonics and Magmatism (ed R. E. Riecker), American Geophysical Union, Washington, D. C.. doi: 10.1029/SP014p0223
- Published Online: 21 MAR 2013
- Published Print: 1 JAN 1979
Print ISBN: 9780875902142
Online ISBN: 9781118664988
- Diablo Plateau movements;
- Espanola basin;
- Geological and geophysical information;
- Geothermal energy;
- Leveling surveys;
- Vertical crustal movements
Analysis of repeated leveling surveys suggests significant contemporary vertical deformation in at least three distinct areas in the vicinity of the Rio Grande rift. These areas include Socorro, New Mexico; the Diablo Plateau region of Trans-Pecos Texas; and the Espanola basin in northern New Mexico. The Socorro area is characterized by uplift relative to its surroundings. Maximum relative uplift of about 20 cm between 1911 and 1951 occurred about 25 km north of Socorro. The primary anomaly, defined by a north-south profile between El Paso, Texas and Albuquerque, New Mexico, extends from 15 km south to 55 km north of Socorro. The Diablo Plateau region is also characterized by relative uplift. Uplift of approximately 13 cm during the period from 1934 to 1958 was observed along an approximately east-west profile from El Paso, Texas to Carlsbad, New Mexico. The leveling anomaly suggests broad uparching of the basin and range structures between El Paso and Carlsbad, with the maximum occurring near the eastern side of the Diablo Plateau. In contrast to the observed relative uplift near Socorro and on the Diablo Plateau, leveling data within the Espanola basin in northern New Mexico show a pronounced zone of relative subsidence. Maximum observed subsidence relative to nearby benchmarks was 4.9 cm between September 1934 and March 1939. Subsidence is observed over a distance of approximately 19 km, extending from 4 km north to 23 km north-northwest of Espanola.
The consistency of available geological and geophysical evidence suggests that these three leveling anomalies are due to crustal deformation and not to measurement errors or near surface effects. Although other possibilities exist, deformation in all three areas can be related, with different degrees of uncertainty, to crustal magmatic activity. This hypothesis is consistent with the tectonic history of the rift, being a predominently extensional environment where magma intrusion might be expected. Tertiary intrusives and crustal conductivity anomalies occur near all three locations. The observed patterns of deformation in all three areas are generally consistent with relatively simple models of magma intrusion in the crust. The Socorro and Espanola areas are seismically active, have high heat flow, are characterized by Quaternary volcanics and are transected by major structural lineaments. On the other hand, the Diablo Plateau region is aseismic at present and lacks evidence of young volcanic activity. The most direct evidence for magma within the crust comes from seismic wave propagation anomalies (reflected phases from magma-crust boundary and filtering effects of low rigidity material) which so far have been detected only in the Socorro area. Thus, although crustal magmatic activity appears to be the most likely cause for the crustal movements described here, the evidence supporting this hypothesis is strongest for the Socorro area.