Basin and Range crustal and upper mantle structure, northwest to central Nevada

Journal Article · Wed Apr 10 04:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/91JB00194· OSTI ID:5456853

Catchings, R D; Mooney, W D ^[1]

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1. Geological Survey, Menlo Park, California (USA)

The authors present an interpretaton of the crustal and uppermost mantel structure of the Basin and Range of northwestern Nevada based on seismic refraction/wide-angle reflection, near-vertical reflection, and gravity data. In comparison to most previous estimates, they find that the crust is somehwat thicker (32-36 km versus 22-30 km), and the uppermost mantel velocity is somewhat higher (8.0 km/s versus 7.3-7.9 km/s). Variations in velocity and structure of the upper crustal layers reveal apparent basement velocity depressions that underlie some surface ranges as well as the basins. The middle crust rises from about 20 km beneath central Nevada to within 12 km of the surface beneath the area of thinnest crust and is characterized by a modest change in velocity and low-velocity gradients. These midcrustal layers mark the onset of high crustal reflectivity and the apparent limiting depth to which Basin and Range faults can be traced in near-vertical reflection profiles, suggesting that these midcrustal layers represent the transition between the brittle and ductile zones of the crust. The geometry of lower crustal layers (derived from refraction modeling) coincides with changes in the crustal reflectivity. Gravity modeling and comparison to existing seismic models show a general consensus in many aspects with respect to crustal structure. This new model forms the basis for speculation on some of the processes associated with rifting of the Basin and Range Province. One such process, lithospheric magmatism, is inferred from the strong attenuation of transmitted seismic waves, which occurs at the same interface at which high-amplitude, bright spot reflections originate. Unlike previous models, the overall structure and velocity of the crust and uppermost mantle of this model are similar to other regions worldwide which have undergone high degrees of extension.

• OSTI ID: 5456853
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 96:B4; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
BASEMENT ROCK
BRITTLENESS
CONTINENTAL CRUST
DEVELOPED COUNTRIES
DIMENSIONS
DUCTILITY
EARTH CRUST
EARTH MANTLE
FEDERAL REGION IX
GEOLOGIC FORMATIONS
GEOLOGIC MODELS
GEOLOGIC STRUCTURES
GEOLOGY
GEOMORPHOLOGY
GEOPHYSICAL SURVEYS
GRAVITY SURVEYS
INTERFACES
MAGMATISM
MECHANICAL PROPERTIES
NEVADA
NORTH AMERICA
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
REFLECTIVITY
REFRACTIVITY
RIFT ZONES
SEDIMENTARY BASINS
SEISMIC SURVEYS
SEISMIC WAVES
SURFACE PROPERTIES
SURVEYS
TENSILE PROPERTIES
THICKNESS
USA
VARIATIONS
WAVE PROPAGATION