Airoldi G.M.,University of Otago |
Airoldi G.M.,Alpine Laboratory of Paleomagnetism |
Muirhead J.D.,University of Auckland |
Muirhead J.D.,University of Idaho |
And 5 more authors.
Tectonophysics | Year: 2016
Magma flow paths in sill-fed dikes of the Ferrar large igneous province (LIP), contrast with those predicted by classic models of dike transport in LIPs and magmatic rift settings. We examine anisotropy of magnetic susceptibility (AMS) flow paths in dike networks at Terra Cotta Mountain and Mt. Gran, which intruded at paleodepths of ~ 2.5 and ~ 1.5 km. These intrusions (up to 30 m thick) exhibit irregular, interconnected dike-sill geometries and adjoin larger sills (~ 200–300 m thick) at different stratigraphic levels. Both shallowly dipping and sub-vertical magma flow components are interpreted from AMS measurements across individual intrusions, and often match macroscopic flow indicators and variations in dike attitudes. Flow paths suggest that intrusive patterns and magma flow directions depended on varying stress concentrations and rotations during dike and sill propagation, whereas a regional extensional tectonic control was negligible or absent. Unlike giant dike swarms in LIPs elsewhere (e.g., 1270 Ma MacKenzie LIP), dikes of the Ferrar LIP show no regionally consistent vertical or lateral flow patterns, suggesting these intrusion were not responsible for long-distance transport in the province. In the absence of regionally significant, colinear dike swarms, or observed intrusions at crustal depths ≥ 4 km, we suggest that long distance magma transport occurred in sills within Beacon Supergroup sedimentary rocks. This interpretation is consistent with existing geochemical data and thermal constraints, which support lateral magma flow for ~ 3,500 km across the Gondwana supercontinent before freezing. © 2016 Elsevier B.V.
Grosfils E.B.,Pomona College |
Mcgovern P.J.,Lunar and Planetary Institute |
Gregg P.M.,Oregon State University |
Galgana G.A.,Lunar and Planetary Institute |
And 7 more authors.
Geological Society Special Publication | Year: 2015
Understanding how shallow reservoirs store and redirect magma is critical for deciphering the relationship between surface and subsurface volcanic activity on the terrestrial planets. Complementing field, laboratory and remote sensing analyses, elastic models provide key insights into the mechanics of magma reservoir inflation and rupture, and hence into commonly observed volcanic phenomena including edifice growth, circumferential intrusion, radial dyke swarm emplacement and caldera formation. Based on finite element model results, the interplay between volcanic elements - such as magma reservoir geometry, host rock environment (with an emphasis on understanding how host rock pore pressure assumptions affect model predictions), mechanical layering, and edifice loading with and without flexure - dictates the overpressure required for rupture, the location and orientation of initial fracturing and intrusion, and the associated surface uplift. Model results are either insensitive to, or can readily incorporate, material and parameter variations characterizing different planetary environments, and they also compare favourably with predictions derived from rheologically complex, time-dependent formulations for a surprisingly diverse array of volcanic scenarios. These characteristics indicate that elastic models are a powerful and useful tool for exploring many fundamental questions in planetary volcanology. © The Geological Society of London 2015.
Wright B.,Hazen and Sawyer |
Smith A.,Brashears and Graham Inc. |
Getchell F.,Brashears and Graham Inc. |
Kane K.,65 Columbus Avenue
Watershed Management Conference 2010: Innovations in Watershed Management under Land Use and Climate Change - Proceedings of the 2010 Watershed Management Conference | Year: 2010
Shale formations with gas producing potential are distributed throughout much of the United States. The process required to extract gas from low permeability shale formations, termed hydraulic fracturing or "fracking," entails injecting large volumes of water, sand, and chemicals at high pressures into the formation, resulting in fractures that increase permeability, allowing the gas to be collected and delivered to the surface. Additionally, wells are generally drilled horizontally underground to increase the area of production for a single well. Whereas variations of the technology have been in use for many years, it has only been in the last decade that the technology has improved to allow economic production from unconventional shale formations on a widespread basis (Airhart, 2007). The technology has been most widely used in the Barnett Shale formation in Texas, which has seen over 13,000 wells developed since 2000 (EIA, 2009; TXRRC, 2009). Portions of the Marcellus Formation, which extends over 95,000 square miles and underlies portions of New York, Pennsylvania, Ohio, and West Virginia, have begun to experience substantial gas leasing and development activity in recent years. The Catskill and Delaware watersheds that provide 90 percent of New York City's unfiltered drinking water supply are underlain by relatively thick sections of the Marcellus that are expected to have high gas production potential (NYCDEP, 2009b). Over 65 percent (∼1,000 square miles) of the NYC watershed could potentially be exploited for natural gas development. Natural gas development activities have the potential to impact the quality and quantity of NYC's water supply through land disturbance, chemical spills, disruption of groundwater flow pathways, water consumption, and waste generation. In recognition of these potential impacts, the New York City Department of Environmental Protection (NYCDEP) has undertaken the project, Impact Assessment of Natural Gas Production in the NYC Water Supply Watershed. The overall goal of the project is to identify potential threats to the continued reliability and high quality of New York City's water supply from future natural gas development activities in or near the NYC watershed. This paper summarizes major findings from this project. © 2011 ASCE.
Chin D.A.,University of Miami |
Iudicello J.J.,University of Miami |
Kajder K.C.,University of Miami |
Kelly P.M.,University of Miami |
And 2 more authors.
Journal of Water Resources Planning and Management | Year: 2010
A computational protocol for particle tracking in wellfields with lakes is proposed. The protocol is demonstrated in the Northwest Wellfield, which is the largest wellfield in Florida and contains many lakes. Comparison of the results with existing regulatory travel-time contours shows that the proposed method produces more realistic results in terms of reflecting the presence of lakes. © 2010 ASCE.
Ayers M.,Brashears and Graham Inc.
Pollution Engineering | Year: 2010
A project was undertaken by Leggette, Brashears & Graham at an old printing plant located in the Borough of Fair Lawn, Bergen County, New Jersey, US, to restore indoor air quality in a building permeated by vapors arising from soil or groundwater that contaminated by chlorinated volatile organic compounds (CVOC). The restoration process required excavation and removal of part of the concrete slab in the building and more than 10,000 tons of impacted soil. An initial remedial investigation was performed to delineate the extent of CVOCs in soil, groundwater, and indoor air. The investigation identified a mass of tetrachloroethylene (PCE)-impacted soil and groundwater contamination beneath a corner of the building. It was also found that the presence of the elevated soil and groundwater contaminant concentrations below the floor slab had impacted the building's indoor air quality at a level that exceeded the NJDEP's Indoor Air Screening Level for PCE of 0.5 parts per billion per volume (ppbv).
Kenyon T.,Brashears and Graham Inc.
Pollution Engineering | Year: 2011
Tim Kenyon explains how the cleanup of a North Dakota diesel spill required expertise, patience and above all, collaboration. Realizing the detrimental effect that pollution was having on real estate values and investments in the impacted area, the city and the state sought a solution that would address the issue once and for all. Information gained from more than 100 existing monitor wells showed that site conditions were very amenable to remediation techniques the engineering consulting firm had successfully applied on other large-scale projects. Installation of the remediation system, including a total of three remediation buildings, 15 remote manifold structures, and multi-phase and soil vapor extraction (SVE) wells along with water and air treatment systems, was a three-year process. Given the scale of the spill and its presence in a densely populated commercial area, the remediation effort has proven to be extremely challenging.