Alternative perspectives of crustal and upper mantle phenomena along the Rio Grande rift
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At various locations along the Rio Grande rift in central and southern New Mexico, USA, heat flow data suggest a rather abrupt change from high values often associated with the rift to lower values characterizing neighboring geologic provinces. With this consideration in mind, we explore possible perspectives derived from seismic cross sections along La Ristra profile crossing New Mexico. In New Mexico, La Ristra transects at ~45° to the generally accepted north-south axis of the Rio Grande rift and more acutely to potential eastern boundaries of the southern rift. Considering foreshortened projections of seismic cross sections, one may be able to better visualize possible advection associated with the Rio Grande rift, although resolution of existing seismic data suggests the narrow, near vertical seismic anomalies in these projections may be hypothetical interpretations. If the foreshortened cross sections are realistic, then upper-mantle upwelling appears to be focused near the Rio Grande rift–Great Plains craton boundary.
Manuscript received 26 Aug. 2009; accepted 22 Aug. 2010