Hydrothermal alteration maps of the central and southern Basin and Range province of the United States compiled from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data

2013 ◽  
Author(s):  
John L. Mars
Keyword(s):  
United States ◽  
Hydrothermal Alteration ◽  
Thermal Emission ◽  
The United States ◽  
Basin And Range ◽  
Basin And Range Province ◽  
Southern Basin ◽  
Aster Data

scholarly journals Porphyry Copper Potential of the United States Southern Basin and Range Using ASTER Data Integrated with Geochemical and Geologic Datasets to Assess Potential Near-Surface Deposits in Well-Explored Permissive Tracts

2019 ◽  
Vol 114 (6) ◽  
pp. 1095-1121
Author(s):  
John C. Mars ◽  
Gilpin R. Robinson ◽  
Jane M. Hammarstrom ◽  
Lukas Zürcher ◽  
Helen Whitney ◽  
...  
Keyword(s):  
United States ◽  
Expert Opinion ◽  
Porphyry Copper ◽  
Basin And Range ◽  
Porphyry Copper Deposits ◽  
Basin And Range Province ◽  
Copper Deposits ◽  
Southern Basin ◽  
Aster Data ◽  
Undiscovered Deposits

Abstract ArcGIS was used to spatially assess and rank potential porphyry copper deposits using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data together with geochemical and geologic datasets in order to estimate undiscovered deposits in the southern Basin and Range Province in the southwestern United States. The assessment was done using a traditional expert opinion three-part method and a prospectivity model developed using weights of evidence and logistic regression techniques to determine if ASTER data integrated with other geologic datasets can be used to find additional areas of prospectivity in well-explored permissive tracts. ASTER hydrothermal alteration data were expressed as 457 alteration polygons defined from a low-pass filtered alteration density map of combined argillic, phyllic, and propylitic rock units. Sediment stream samples were plotted as map grid data and used as spatial information in ASTER polygons. Gravity and magnetic data were also used to define basins greater than 1 km in depth. Each ASTER alteration polygon was ranked for porphyry copper potential using alteration types, spatial amounts of alteration, stream sediment geochemistry, lithology, polygon shape, proximity to other alteration polygons, and deposit and prospects data. Permissive tracts defined for the assessment in the southern Basin and Range Province include the Laramide Northwest, Laramide Southeast, Jurassic, and Tertiary tracts. Expert opinion estimates using the three-part assessment method resulted in a mean estimate of 17 undiscovered porphyry copper deposits, whereas the prospectivity modeling predicted a mean estimate of nine undiscovered deposits. In the well-explored Laramide Southeast tract, which contains the most deposits and has been explored for over 100 years, an average of 4.3 undiscovered deposits was estimated using ASTER alteration polygon data versus 2.8 undiscovered deposits without ASTER data. The Tertiary tract, which contains the largest number of ASTER alteration polygons not associated with known Tertiary deposits, was predicted to contain the most undiscovered resources in the southern Basin and Range Province.

Regional variation and frequency dependence of Qβ in the crust of the United States

1981 ◽  
Vol 71 (5) ◽  
pp. 1531-1538
Author(s):  
Brian J. Mitchell
Keyword(s):  
United States ◽  
Frequency Dependence ◽  
Colorado Plateau ◽  
The United States ◽  
Basin And Range ◽  
Small Degree ◽  
Eastern United States ◽  
Basin And Range Province ◽  
Period Range ◽  
Attenuation Coefficients

abstract Approximate Lg attenuation coefficient values are determined for paths in eastern North America at periods between 2 and 4 sec where no data were previously available. These new data, together with reported values at a period of 1 sec, are consistent with values predicted by a frequency-dependentent Qβ of the crust in which Qβ varies as ω0.2. The new data are inconsistent with values which would be predicted by models having prominent maxima or minima in Qβ−1 within the period range 1 to 5 sec. Lg attenuation coefficients were computed for the frequency-independent crustal Qβ models of Cheng and Mitchell (1981) for the Basin and Range Province and Colorado Plateau of the Western United States. The predicted values at 1 sec for the Colorado Plateau and Basin and Range Province are about twice as large, and three times as large, respectively, as those predicted for the Eastern United States. Recently reported values of Q for 1-sec Lg in those regions are consistent with the attenuation coefficients and Q values of Lg predicted by the Colorado Plateau and Basin and Range Province models. A model with a small degree of frequency dependence of Qβ would be consistent, but is not required by the data.

Regional Lg attenuation for the continental United States

1997 ◽  
Vol 87 (3) ◽  
pp. 606-619 ◽  
Author(s):  
Harley M. Benz ◽  
Arthur Frankel ◽  
David M. Boore
Keyword(s):  
United States ◽  
Frequency Band ◽  
Southern California ◽  
Basin And Range ◽  
Northeastern United States ◽  
Basin And Range Province ◽  
Frequency Dependent ◽  
Low Frequencies ◽  
Central United States ◽  
Q Function

Abstract Measurements of the Fourier amplitude spectra of Lg phases recorded at high frequency (0.5 to 14.0 Hz) by broadband seismic stations are used to determine regional attenuation relationships for southern California, the Basin and Range Province, the central United States, and the northeastern United States and southeastern Canada. Fourier spectral amplitudes were measured every quarter octave from Lg phases windowed between 3.0 and 3.7 km sec−1 and recorded in the distance range of 150 to 1000 km. Attenuation at each frequency is determined by assuming a geometrical spreading exponent of 0.5 and inverting for Q and source and receiver terms. Both southern California and the Basin and Range Province are well described by low Lg Q and frequency-dependent attenuation. Lg spectral amplitudes in southern California are fit at low frequencies (0.625 to 0.875 Hz) by a constant Lg Q of 224 and by a frequency-dependent Lg Q function Q = 187−7+7f0.55(±0.03) in the frequency band 1.0 to 7.0 Hz. The Basin and Range Province is characterized by a constant Lg Q of 192 for frequencies of 0.5 to 0.875 Hz and by the frequency-dependent Lg Q function Q = 235−11+11f0.56(±0.04) in the frequency band 1.0 to 5.0 Hz. A change in frequency dependence above 5.0 Hz is possible due to contamination of the Lg window by Pn and Sn phases. Lg spectral amplitudes in the central United States are fit by a mean frequency-independent Lg Q of 1291 for frequencies of 1.5 to 7.0 Hz, while a frequency-dependent Lg Q of Q = 1052−83+91(f/1.5)0.22(±0.06) fits the Lg spectral amplitudes for the northeastern United States and southeastern Canada over the passband 1.5 to 14.0 Hz. Attenuation measurements for these areas were restricted to frequencies >1.5 Hz due to larger microseismic noise levels at the lower frequencies.

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