Geographic Extent and Shape of an Extensive Magma Body at Mid-Crustal Depths in the Rio Grande Rift Near Socorro, New Mexico.

  1. Robert E. Riecker
  1. Eric J. Rinehart,
  2. Allan R. Sanford and
  3. Roger M. Ward

Published Online: 21 MAR 2013

DOI: 10.1029/SP014p0237

Rio Grande Rift: Tectonics and Magmatism

Rio Grande Rift: Tectonics and Magmatism

How to Cite

Rinehart, E. J., Sanford, A. R. and Ward, R. M. (1979) Geographic Extent and Shape of an Extensive Magma Body at Mid-Crustal Depths in the Rio Grande Rift Near Socorro, New Mexico., in Rio Grande Rift: Tectonics and Magmatism (ed R. E. Riecker), American Geophysical Union, Washington, D. C.. doi: 10.1029/SP014p0237

Author Information

  1. Geoscience Department and Geophysical Research Center, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801

Publication History

  1. Published Online: 21 MAR 2013
  2. Published Print: 1 JAN 1979

ISBN Information

Print ISBN: 9780875902142

Online ISBN: 9781118664988

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Keywords:

  • Extensive magma body;
  • Geodetic measurements;
  • Geologic and geophysical characteristics;
  • Microearthquake;
  • Refraction;
  • Seismograms;
  • Surface relief

Summary

Depth, geographic extent, and relief on a mid-crustal magma layer in the Rio Grande rift near Socorro were determined from 220 accurately located S-wave reflection points obtained from a microearthquake study. Important additional controls on the configuration of the magma body were obtained from COCORP P-wave reflection data. As presently mapped, the magma occurs as a thin flat sill at depths of 19 to 20 km beneath 1700 km2 of the central part of the rift. Geodetic data in the Socorro area indicate horizontal compressive strain over the region and thus magma bodies of this configuration are possible. A control on the placement of the sill could be a resistive rock layer immediately above the Conrad discontinuity. An unusual feature of the magma layer is its lack of relief beneath surface structures with large vertical displacements. This may indicate possible detachment of the brittle uppermost crust from a plastic zone at lower levels.