干旱区生态环境知识资源中心(Arid): Gravity and magnetic study of the Pahute Mesa and Oasis Valley region, Nye County, Nevada

Arid

DOI	10.2172/10449
报告编号	USGS OFR 99-303
来源ID	OSTI_ID: 10449
	Gravity and magnetic study of the Pahute Mesa and Oasis Valley region, Nye County, Nevada
	Mankinen, Edward A. emank@usgs.gov; Hildenbrand, Thomas G.; Dixon, Gary L.; McKee, Edwin H. mckee@usgs.gov; Fridrich, Christopher J. fridrich@usgs.gov; Laczniak, Randell J.
英文摘要	Regional gravity and aeromagnetic maps reveal the existence of deep basins underlying much of the southwestern Nevada volcanic field, approximately 150 km northwest of Las Vegas. These maps also indicate the presence of prominent features (geophysical lineaments) within and beneath the basin fill. Detailed gravity surveys were conducted in order to characterize the nature of the basin boundaries, delineate additional subsurface features, and evaluate their possible influence on the movement of ground water. Geophysical modeling of gravity and aeromagnetic data indicates that many of the features may be related to processes of caldera formation. Collapse of the various calderas within the volcanic field resulted in dense basement rocks occurring at greater depths within caldera boundaries. Modeling indicates that collapse occurred along faults that are arcuate and steeply dipping. There are indications that the basement in the western Pahute Mesa - Oasis Valley region consists predominantly of granitic and/or fine-grained siliceous sedimentary rocks that may be less permeable to ground-water flow than the predominantly fractured carbonate rock basement to the east and southeast of the study area. The northeast-trending Thirsty Canyon lineament, expressed on gravity and basin thickness maps, separates dense volcanic rocks on the northwest from less dense intracaldera accumulations in the Silent Canyon and Timber Mountain caldera complexes. The sources of the lineament is an approximately 2-km wide ring fracture system with step-like differential displacements, perhaps localized on a pre-existing northeast-trending Basin and Range fault. Due to vertical offsets, the Thirsty Canyon faults zone probably juxtaposes rock types of different permeability and, thus, it may act as a barrier to ground-water flow and deflect flow from Pahute Mesa along its flanks toward Oasis Valley. Within the Thirsty Canyon fault zone, highly fractured rocks may serve also as a conduit, depending upon the degree of alteration and its effect on porosity and permeability. In the Oasis Valley region, other structures that may influence ground-water flow include the western and southern boundaries of the Oasis Valley basin, where the basement abruptly shallows.
出版年	1999
报告类型	Technical Report
语种	英语
国家	美国
来源学科分类	58 GEOSCIENCES ; 54 ENVIRONMENTAL SCIENCES ; BASEMENT ROCK ; CARBONATE ROCKS ; GEOLOGIC STRUCTURES ; GRAVITY SURVEYS ; GROUND WATER ; PERMEABILITY ; POROSITY ; SEDIMENTARY ROCKS ; THICKNESS OASIS VALLEY ; NEVADA ; GEOHYDROLOGY ; AEROMAGNETIC DATA ; GRAVITY DATA ; PAHUTE MESA
URL	http://www.osti.gov/scitech/servlets/purl/10449
资源类型	科技报告
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/267871
推荐引用方式 GB/T 7714	Mankinen, Edward A. emank@usgs.gov,Hildenbrand, Thomas G.,Dixon, Gary L.,et al. Gravity and magnetic study of the Pahute Mesa and Oasis Valley region, Nye County, Nevada,1999.