Thermal, mechanical and tectonic evolution of the southern Rio Grande rift. [Abstract only]
- Lunar and Planetary Inst., Houston, TX
Geological and geophysical data reasonably define the Cenozoic evolution and crustal and upper mantle structure of southwestern New Mexico, and constrain thermomechanical models of the tectonic evolution of the southern Rio Grande rift. Four overlapping, possibly interrelated geological events have been identified: (1) Laramide deformation; (2) voluminous volcanic activity (approx. 43 to approx. 21 My); (3) development of broad, relatively deep north-west trending basins (starting about 28 to 29 My), with associated volcanism; and (4) block faulting and volcanism (9 to 3 My) with development of the modern northerly trending rift basins, and regional uplift. The southern Rio Grande rift is characterized by high heat flow, and seismic, gravity and electrical data indicate anomalous structure in the lower crust and/or uppermost mantle beneath the rift. The first voluminous volcanic event caused significant heating of the crust in an arc environment, and probably caused crustal melting. The brittle/ductile transition was very shallow (<10 km), and with a change to an extensional stress regime, north-west trending basins developed in response to lithospheric necking, with continued volcanism in a back-arc environment. During the mid Miocene, the crust cooled, the brittle/ductile transition became deeper, and when a new extensional stress regime was established (approx. 9 My), the northerly trending modern fault block basins were developed. Lower lithospheric extension during this second extensional phase was probably accommodated by plastic deformation and basaltic intrusion, the latter maintaining the modern high heat flow. Thus, thermal events and regional stresses have controlled the style and timing of rifting in southwestern New Mexico.
- OSTI ID:
- 6020157
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Vol. 15:5; ISSN GAAPB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
150201 -- Geology & Hydrology of Geothermal Systems-- USA-- (-1989)
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BASALT
FEDERAL REGION VI
GEOLOGIC HISTORY
HEAT FLOW
IGNEOUS ROCKS
INTRUSION
NEW MEXICO
NORTH AMERICA
RIO GRANDE RIFT
ROCKS
USA
VOLCANIC ROCKS