Geoffrey Phelps, MSc
Phelps works in the GMEG Science Center. He received a BA in geology from UC Berkeley and an MSc from the University of London, Birkbeck in geographic information science. He specializes in geologic mapping, gravity and magnetics, and spatial analysis. Presently his research is focused on using data science tools in 2D and 3D geologic mapping, and gravity and magnetic forward and inverse modeling.
Science and Products
Filter Total Items: 27
Stochastic modeling of a lava-flow aquifer system Stochastic modeling of a lava-flow aquifer system
This report describes preliminary three-dimensional geostatistical modeling of a lava-flow aquifer system using a multiple-point geostatistical model. The purpose of this study is to provide a proof-of-concept for this modeling approach. An example of the method is demonstrated using a subset of borehole geologic data and aquifer test data from a portion of the Calico Hills Formation, a...
Authors
Collin Cronkite-Ratcliff, Geoffrey A. Phelps
Investigations into near-real-time surveying for geophysical data collection using an autonomous ground vehicle Investigations into near-real-time surveying for geophysical data collection using an autonomous ground vehicle
The U.S. Geological Survey and the National Aeronautics and Space Administration are cooperatively investigating the utility of unmanned vehicles for near-real-time autonomous surveys of geophysical data collection. Initially focused on unmanned ground vehicle collection of magnetic data, this cooperative effort has brought unmanned surveying, precision guidance, near-real-time...
Authors
Geoffrey A. Phelps, C. Ippolito, R. Lee, R. Spritzer, Y. Yeh
Payload-directed control of geophysical magnetic surveys Payload-directed control of geophysical magnetic surveys
No abstract available.
Authors
Ritchie Lee, Yoo-Hsiu Yeh, C. Ippolito, John Spritzer, Geoffrey Phelps
Inversion of Gravity Data to Define the Pre-Cenozoic Surface and Regional Structures Possibly Influencing Groundwater Flow in the Rainier Mesa Region, Nye County, Nevada Inversion of Gravity Data to Define the Pre-Cenozoic Surface and Regional Structures Possibly Influencing Groundwater Flow in the Rainier Mesa Region, Nye County, Nevada
A three-dimensional inversion of gravity data from the Rainier Mesa area and surrounding regions reveals a topographically complex pre-Cenozoic basement surface. This model of the depth to pre-Cenozoic basement rocks is intended for use in a 3D hydrogeologic model being constructed for the Rainier Mesa area. Prior to this study, our knowledge of the depth to pre-Cenozoic basement rocks...
Authors
Thomas G. Hildenbrand, Geoffrey A. Phelps, Edward A. Mankinen
Preliminary surficial geologic map database of the Amboy 30 x 60 minute quadrangle, California Preliminary surficial geologic map database of the Amboy 30 x 60 minute quadrangle, California
The surficial geologic map database of the Amboy 30x60 minute quadrangle presents characteristics of surficial materials for an area approximately 5,000 km2 in the eastern Mojave Desert of California. This map consists of new surficial mapping conducted between 2000 and 2005, as well as compilations of previous surficial mapping. Surficial geology units are mapped and described based on
Authors
David R. Bedford, David M. Miller, Geoffrey A. Phelps
Preliminary gravity inversion model of basins east of Yucca Flat, Nevada Test Site, Nevada Preliminary gravity inversion model of basins east of Yucca Flat, Nevada Test Site, Nevada
No abstract available.
Authors
Geoffrey A. Phelps, Carter W. Roberts, Barry C. Moring
A Preliminary Investigation of The Structure of Southern Yucca Flat, Massachusetts Mountain, and CP Basin, Nevada Test Site, Nevada, Based on Geophysical Modeling A Preliminary Investigation of The Structure of Southern Yucca Flat, Massachusetts Mountain, and CP Basin, Nevada Test Site, Nevada, Based on Geophysical Modeling
New gravity and magnetic data collected in the vicinity of Massachusetts Mountain and CP basin (Nevada Test Site, NV) provides a more complex view of the structural relationships present in the vicinity of CP basin than previous geologic models, helps define the position and extent of structures in southern Yucca Flat and CP basin, and better constrains the configuration of the basement...
Authors
Geoffrey A. Phelps, Leigh Justet, Barry C. Moring, Carter W. Roberts
Modeling of the Climax Stock and Related Plutons Based on the Inversion of Magnetic Data, Southwest Nevada Modeling of the Climax Stock and Related Plutons Based on the Inversion of Magnetic Data, Southwest Nevada
Two models of the Climax and Gold Meadows stocks were generated using a new method of magnetic inversion modeling based on the pseudogravity anomaly. The first model examined the shape of the two stocks and their connection at depth, concluding that the stocks are connected -4000 m below the ground surface. The second model re-examined the shape and depth of the Climax stock using a two...
Authors
Geoffrey A. Phelps, Robert C. Jachens, Barry C. Moring, Carter W. Roberts
Geologic map of the Hiller Mountain Quadrangle, Clark County, Nevada, and Mohave County, Arizona Geologic map of the Hiller Mountain Quadrangle, Clark County, Nevada, and Mohave County, Arizona
Map Scale: 1:24,000 Map Type: colored geologic map The Hiller Mountains Quadrangle straddles Virgin Canyon in the eastern part of Lake Mead. Proterozoic gneisses and granitoid rocks underlie much of the quadrangle. They are overlain by upper Miocene basin-filling deposits of arkosic conglomerate, basalt, and the overlying Hualapai Limestone. Inception of the Colorado River followed...
Authors
Keith A. Howard, Simon Hook, Geoffrey A. Phelps, Debra L. Block
Preliminary gravity inversion model of Frenchman Flat Basin, Nevada Test Site, Nevada Preliminary gravity inversion model of Frenchman Flat Basin, Nevada Test Site, Nevada
The depth of the basin beneath Frenchman Flat is estimated using a gravity inversion method. Gamma-gamma density logs from two wells in Frenchman Flat constrained the density profiles used to create the gravity inversion model. Three initial models were considered using data from one well, then a final model is proposed based on new information from the second well. The preferred model...
Authors
Geoffrey A. Phelps, Scott E. Graham
Preliminary model of the pre-Tertiary basement rocks beneath Yucca Flat, Nevada Test Site, Nevada, based on analysis of gravity and magnetic data Preliminary model of the pre-Tertiary basement rocks beneath Yucca Flat, Nevada Test Site, Nevada, based on analysis of gravity and magnetic data
The Environmental Restoration Program of the U.S. Department of Energy, Nevada Operations Office, was developed to investigate the possible consequences to the environment of 40 years of nuclear testing on the Nevada Test Site. The majority of the tests were detonated underground, introducing contaminants into the ground-water system (Laczniak and others, 1996). An understanding of the...
Authors
Geoffrey A. Phelps, Edwin H. McKee, D. Sweetkind, V.E. Langenheim
Principal facts for gravity stations in the vicinity of Coyote Spring Valley, Nevada, with initial gravity modeling results Principal facts for gravity stations in the vicinity of Coyote Spring Valley, Nevada, with initial gravity modeling results
Gravity measurements were made along 5 profiles across parts of the Coyote Spring Valley and vicinity in order to aid in modeling the depth and shapes of the underlying basins and to locate faults concealed beneath the basin fill. Measurements were taken at 200 m (660 ft) spacing along the profiles. Models based on these and existing regional data reveal two north-south-trending basins...
Authors
Geoffrey A. Phelps, E. B. Jewel, V.E. Langenheim, R.C. Jachens
Science and Products
Filter Total Items: 27
Stochastic modeling of a lava-flow aquifer system Stochastic modeling of a lava-flow aquifer system
This report describes preliminary three-dimensional geostatistical modeling of a lava-flow aquifer system using a multiple-point geostatistical model. The purpose of this study is to provide a proof-of-concept for this modeling approach. An example of the method is demonstrated using a subset of borehole geologic data and aquifer test data from a portion of the Calico Hills Formation, a...
Authors
Collin Cronkite-Ratcliff, Geoffrey A. Phelps
Investigations into near-real-time surveying for geophysical data collection using an autonomous ground vehicle Investigations into near-real-time surveying for geophysical data collection using an autonomous ground vehicle
The U.S. Geological Survey and the National Aeronautics and Space Administration are cooperatively investigating the utility of unmanned vehicles for near-real-time autonomous surveys of geophysical data collection. Initially focused on unmanned ground vehicle collection of magnetic data, this cooperative effort has brought unmanned surveying, precision guidance, near-real-time...
Authors
Geoffrey A. Phelps, C. Ippolito, R. Lee, R. Spritzer, Y. Yeh
Payload-directed control of geophysical magnetic surveys Payload-directed control of geophysical magnetic surveys
No abstract available.
Authors
Ritchie Lee, Yoo-Hsiu Yeh, C. Ippolito, John Spritzer, Geoffrey Phelps
Inversion of Gravity Data to Define the Pre-Cenozoic Surface and Regional Structures Possibly Influencing Groundwater Flow in the Rainier Mesa Region, Nye County, Nevada Inversion of Gravity Data to Define the Pre-Cenozoic Surface and Regional Structures Possibly Influencing Groundwater Flow in the Rainier Mesa Region, Nye County, Nevada
A three-dimensional inversion of gravity data from the Rainier Mesa area and surrounding regions reveals a topographically complex pre-Cenozoic basement surface. This model of the depth to pre-Cenozoic basement rocks is intended for use in a 3D hydrogeologic model being constructed for the Rainier Mesa area. Prior to this study, our knowledge of the depth to pre-Cenozoic basement rocks...
Authors
Thomas G. Hildenbrand, Geoffrey A. Phelps, Edward A. Mankinen
Preliminary surficial geologic map database of the Amboy 30 x 60 minute quadrangle, California Preliminary surficial geologic map database of the Amboy 30 x 60 minute quadrangle, California
The surficial geologic map database of the Amboy 30x60 minute quadrangle presents characteristics of surficial materials for an area approximately 5,000 km2 in the eastern Mojave Desert of California. This map consists of new surficial mapping conducted between 2000 and 2005, as well as compilations of previous surficial mapping. Surficial geology units are mapped and described based on
Authors
David R. Bedford, David M. Miller, Geoffrey A. Phelps
Preliminary gravity inversion model of basins east of Yucca Flat, Nevada Test Site, Nevada Preliminary gravity inversion model of basins east of Yucca Flat, Nevada Test Site, Nevada
No abstract available.
Authors
Geoffrey A. Phelps, Carter W. Roberts, Barry C. Moring
A Preliminary Investigation of The Structure of Southern Yucca Flat, Massachusetts Mountain, and CP Basin, Nevada Test Site, Nevada, Based on Geophysical Modeling A Preliminary Investigation of The Structure of Southern Yucca Flat, Massachusetts Mountain, and CP Basin, Nevada Test Site, Nevada, Based on Geophysical Modeling
New gravity and magnetic data collected in the vicinity of Massachusetts Mountain and CP basin (Nevada Test Site, NV) provides a more complex view of the structural relationships present in the vicinity of CP basin than previous geologic models, helps define the position and extent of structures in southern Yucca Flat and CP basin, and better constrains the configuration of the basement...
Authors
Geoffrey A. Phelps, Leigh Justet, Barry C. Moring, Carter W. Roberts
Modeling of the Climax Stock and Related Plutons Based on the Inversion of Magnetic Data, Southwest Nevada Modeling of the Climax Stock and Related Plutons Based on the Inversion of Magnetic Data, Southwest Nevada
Two models of the Climax and Gold Meadows stocks were generated using a new method of magnetic inversion modeling based on the pseudogravity anomaly. The first model examined the shape of the two stocks and their connection at depth, concluding that the stocks are connected -4000 m below the ground surface. The second model re-examined the shape and depth of the Climax stock using a two...
Authors
Geoffrey A. Phelps, Robert C. Jachens, Barry C. Moring, Carter W. Roberts
Geologic map of the Hiller Mountain Quadrangle, Clark County, Nevada, and Mohave County, Arizona Geologic map of the Hiller Mountain Quadrangle, Clark County, Nevada, and Mohave County, Arizona
Map Scale: 1:24,000 Map Type: colored geologic map The Hiller Mountains Quadrangle straddles Virgin Canyon in the eastern part of Lake Mead. Proterozoic gneisses and granitoid rocks underlie much of the quadrangle. They are overlain by upper Miocene basin-filling deposits of arkosic conglomerate, basalt, and the overlying Hualapai Limestone. Inception of the Colorado River followed...
Authors
Keith A. Howard, Simon Hook, Geoffrey A. Phelps, Debra L. Block
Preliminary gravity inversion model of Frenchman Flat Basin, Nevada Test Site, Nevada Preliminary gravity inversion model of Frenchman Flat Basin, Nevada Test Site, Nevada
The depth of the basin beneath Frenchman Flat is estimated using a gravity inversion method. Gamma-gamma density logs from two wells in Frenchman Flat constrained the density profiles used to create the gravity inversion model. Three initial models were considered using data from one well, then a final model is proposed based on new information from the second well. The preferred model...
Authors
Geoffrey A. Phelps, Scott E. Graham
Preliminary model of the pre-Tertiary basement rocks beneath Yucca Flat, Nevada Test Site, Nevada, based on analysis of gravity and magnetic data Preliminary model of the pre-Tertiary basement rocks beneath Yucca Flat, Nevada Test Site, Nevada, based on analysis of gravity and magnetic data
The Environmental Restoration Program of the U.S. Department of Energy, Nevada Operations Office, was developed to investigate the possible consequences to the environment of 40 years of nuclear testing on the Nevada Test Site. The majority of the tests were detonated underground, introducing contaminants into the ground-water system (Laczniak and others, 1996). An understanding of the...
Authors
Geoffrey A. Phelps, Edwin H. McKee, D. Sweetkind, V.E. Langenheim
Principal facts for gravity stations in the vicinity of Coyote Spring Valley, Nevada, with initial gravity modeling results Principal facts for gravity stations in the vicinity of Coyote Spring Valley, Nevada, with initial gravity modeling results
Gravity measurements were made along 5 profiles across parts of the Coyote Spring Valley and vicinity in order to aid in modeling the depth and shapes of the underlying basins and to locate faults concealed beneath the basin fill. Measurements were taken at 200 m (660 ft) spacing along the profiles. Models based on these and existing regional data reveal two north-south-trending basins...
Authors
Geoffrey A. Phelps, E. B. Jewel, V.E. Langenheim, R.C. Jachens