Margaret Mangan, PhD (Former Employee)
Science and Products
Filter Total Items: 28
Volcanic unrest and hazard communication in Long Valley Volcanic Region, California Volcanic unrest and hazard communication in Long Valley Volcanic Region, California
The onset of volcanic unrest in Long Valley Caldera, California, in 1980 and the subsequent fluctuations in unrest levels through May 2016 illustrate: (1) the evolving relations between scientists monitoring the unrest and studying the underlying tectonic/magmatic processes and their implications for geologic hazards, and (2) the challenges in communicating the significance of the...
Authors
David P. Hill, Margaret T. Mangan, Stephen R. McNutt
Thermal and petrologic constraints on lower crustal melt accumulation under the Salton Sea Geothermal Field Thermal and petrologic constraints on lower crustal melt accumulation under the Salton Sea Geothermal Field
In the Salton Sea region of southern California (USA), concurrent magmatism, extension, subsidence, and sedimentation over the past 0.5 to 1.0 Ma have led to the creation of the Salton Sea Geothermal Field (SSGF)—the second largest and hottest geothermal system in the continental United States—and the small-volume rhyolite eruptions that created the Salton Buttes. In this study, we...
Authors
Ozge Karakas, Josef Dufek, Margaret T. Mangan, Heather M. Wright, Olivier Bachmann
Three-dimensional electrical resistivity model of the hydrothermal system in Long Valley Caldera, California, from magnetotellurics Three-dimensional electrical resistivity model of the hydrothermal system in Long Valley Caldera, California, from magnetotellurics
Though shallow flow of hydrothermal fluids in Long Valley Caldera, California, has been well studied, neither the hydrothermal source reservoir nor heat source has been well characterized. Here a grid of magnetotelluric data were collected around the Long Valley volcanic system and modeled in 3-D. The preferred electrical resistivity model suggests that the source reservoir is a narrow...
Authors
Jared R. Peacock, Margaret T. Mangan, Darcy McPhee, Phil E. Wannamaker
Imaging the magmatic system of Mono Basin, California with magnetotellurics in three--dimensions Imaging the magmatic system of Mono Basin, California with magnetotellurics in three--dimensions
A three–dimensional (3D) electrical resistivity model of Mono Basin in eastern California unveils a complex subsurface filled with zones of partial melt, fluid–filled fracture networks, cold plutons, and regional faults. In 2013, 62 broadband magnetotelluric (MT) stations were collected in an array around southeastern Mono Basin from which a 3D electrical resistivity model was created...
Authors
Jared R. Peacock, Margaret T. Mangan, Darcy McPhee, David A. Ponce
Coupled interactions between volatile activity and Fe oxidation state during arc crustal processes Coupled interactions between volatile activity and Fe oxidation state during arc crustal processes
Arc magmas erupted at the Earth’s surface are commonly more oxidized than those produced at mid-ocean ridges. Possible explanations for this high oxidation state are that the transfer of fluids during the subduction process results in direct oxidation of the sub-arc mantle wedge, or that oxidation is caused by the effect of later crustal processes, including protracted fractionation and...
Authors
Madeleine C.S. Humphreys, R Brooker, D.C. Fraser, A Burgisser, Margaret T. Mangan, C McCammon
Episodic Holocene eruption of the Salton Buttes rhyolites, California, from paleomagnetic, U-Th, and Ar/Ar dating Episodic Holocene eruption of the Salton Buttes rhyolites, California, from paleomagnetic, U-Th, and Ar/Ar dating
In the Salton Trough, CA, five rhyolite domes form the Salton Buttes: Mullet Island, Obsidian Butte, Rock Hill, North and South Red Hill, from oldest to youngest. Results presented here include 40Ar/39Ar anorthoclase ages, 238U-230Th zircon crystallization ages, and comparison of remanent paleomagnetic directions with the secular variation curve, which indicate that all domes are...
Authors
Heather M. Wright, Jorge A. Vazquez, Duane E. Champion, Andrew T. Calvert, Margaret T. Mangan, Mark E. Stelten, Kari M. Cooper, Charles Herzig, Alexander Schriener
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 28
Volcanic unrest and hazard communication in Long Valley Volcanic Region, California Volcanic unrest and hazard communication in Long Valley Volcanic Region, California
The onset of volcanic unrest in Long Valley Caldera, California, in 1980 and the subsequent fluctuations in unrest levels through May 2016 illustrate: (1) the evolving relations between scientists monitoring the unrest and studying the underlying tectonic/magmatic processes and their implications for geologic hazards, and (2) the challenges in communicating the significance of the...
Authors
David P. Hill, Margaret T. Mangan, Stephen R. McNutt
Thermal and petrologic constraints on lower crustal melt accumulation under the Salton Sea Geothermal Field Thermal and petrologic constraints on lower crustal melt accumulation under the Salton Sea Geothermal Field
In the Salton Sea region of southern California (USA), concurrent magmatism, extension, subsidence, and sedimentation over the past 0.5 to 1.0 Ma have led to the creation of the Salton Sea Geothermal Field (SSGF)—the second largest and hottest geothermal system in the continental United States—and the small-volume rhyolite eruptions that created the Salton Buttes. In this study, we...
Authors
Ozge Karakas, Josef Dufek, Margaret T. Mangan, Heather M. Wright, Olivier Bachmann
Three-dimensional electrical resistivity model of the hydrothermal system in Long Valley Caldera, California, from magnetotellurics Three-dimensional electrical resistivity model of the hydrothermal system in Long Valley Caldera, California, from magnetotellurics
Though shallow flow of hydrothermal fluids in Long Valley Caldera, California, has been well studied, neither the hydrothermal source reservoir nor heat source has been well characterized. Here a grid of magnetotelluric data were collected around the Long Valley volcanic system and modeled in 3-D. The preferred electrical resistivity model suggests that the source reservoir is a narrow...
Authors
Jared R. Peacock, Margaret T. Mangan, Darcy McPhee, Phil E. Wannamaker
Imaging the magmatic system of Mono Basin, California with magnetotellurics in three--dimensions Imaging the magmatic system of Mono Basin, California with magnetotellurics in three--dimensions
A three–dimensional (3D) electrical resistivity model of Mono Basin in eastern California unveils a complex subsurface filled with zones of partial melt, fluid–filled fracture networks, cold plutons, and regional faults. In 2013, 62 broadband magnetotelluric (MT) stations were collected in an array around southeastern Mono Basin from which a 3D electrical resistivity model was created...
Authors
Jared R. Peacock, Margaret T. Mangan, Darcy McPhee, David A. Ponce
Coupled interactions between volatile activity and Fe oxidation state during arc crustal processes Coupled interactions between volatile activity and Fe oxidation state during arc crustal processes
Arc magmas erupted at the Earth’s surface are commonly more oxidized than those produced at mid-ocean ridges. Possible explanations for this high oxidation state are that the transfer of fluids during the subduction process results in direct oxidation of the sub-arc mantle wedge, or that oxidation is caused by the effect of later crustal processes, including protracted fractionation and...
Authors
Madeleine C.S. Humphreys, R Brooker, D.C. Fraser, A Burgisser, Margaret T. Mangan, C McCammon
Episodic Holocene eruption of the Salton Buttes rhyolites, California, from paleomagnetic, U-Th, and Ar/Ar dating Episodic Holocene eruption of the Salton Buttes rhyolites, California, from paleomagnetic, U-Th, and Ar/Ar dating
In the Salton Trough, CA, five rhyolite domes form the Salton Buttes: Mullet Island, Obsidian Butte, Rock Hill, North and South Red Hill, from oldest to youngest. Results presented here include 40Ar/39Ar anorthoclase ages, 238U-230Th zircon crystallization ages, and comparison of remanent paleomagnetic directions with the secular variation curve, which indicate that all domes are...
Authors
Heather M. Wright, Jorge A. Vazquez, Duane E. Champion, Andrew T. Calvert, Margaret T. Mangan, Mark E. Stelten, Kari M. Cooper, Charles Herzig, Alexander Schriener
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.