By inverting EarthScope long-period magnetotelluric (MT) data from the southeastern United States (SEUS), we obtain electrical conductivity images that provides key insights into the geodynamics of this region. Significantly, we resolve a highly electrically resistive block that extends to mantle depths beneath the modern Piedmont and Coastal Plain physiographic provinces....
The area studied in detail, known as the Antone District,
is located in the southeast corner of Wheeler County, Oregon, ,
between longitude 119 37. and 119°54 east, and latitude 44°23
and 44°3O' north.
Surface elevations range from 3050 feet above sea level in
the northeast corner of the district,...
There are seven stratigraphic units exposed in the Picture
Gorge quadrangle, a 204-square mile area in east-central Oregon.
isolated exposures of pre-Cretaceous serpentinites, metalimestones,
and other metamorphic rocks record marine deposition
of sands silts, and limy sediments followed by burial, lithification,
peridotite intrusion, and several periods of deformation. Intrusion
and...
The thesis area covers 165 square miles including the greater
part of the northeastern quarter of the Mitchell quadrangle in north-central Oregon. The three stratigraphic units exposed in the area
consist of a variety of Tertiary volcanic rocks including the Clarno
Formation, the John Day Formation, and the Columbia River...
The Greenstone Mountain area, which includes the Utopia mining
district, is located in the foothills of the Pioneer Range, Beaverhead
County, Montana. Approximately 12, 600 feet of Paleozoic and
Mesozoic sedimentary rocks and an undetermined thickness of Precambrian
sediments and Late Cretaceous igneous rocks are exposed
within the area of...
The Murderers Creek Area, within the Aldrich Mountain province of
northeast Oregon, originated in an arc-trench gap during Permian-early
Triassic time. The area represents a small portion of a forearc
depositional basin and tectonic highland which borders the basin along
its seaward margin. The trench associated with an east dipping...
Rocks south of the Main Mantle Thrust (MMT) in Swat,
Pakistan consist predominantly of Precambrian to Paleozoic
granitic gneisses and metasedimentary rocks that represent
the deformed and metamorphosed northern margin of the Indian
subcontinent. In the Karakar Pass area the rocks are divisible into three lithologic units: the Swat granite...
The type section of the Mascall Formation, which is located in
the John Day Valley, is interpreted to represent a sequence of
paleosols. These fossil soils were formed on a floodplain during the
middle Miocene. The measured thickness of this section is 1340 feet,
and although the top of the...
The Nanga Parbat-Haramosh massif (NPHM) is a unique structural
and topographic high in the northwestern corner of the Himalayan
convergence zone. Previously, the NPHM was thought to be bounded by
the MMT, a thrust along which the Kohistan-Ladakh island arc was
obducted onto the northern margin of fridia. This study...
Estimates of average annual precipitation (AAP) are-needed for hydrologic modeling at
Yucca Mtn., Nevada, site of a proposed, high-level nuclear waste repository. Historical
precipitation data and station elevation were obtained for stations in southern Nevada and
southeastern California. Elevations for 1,531 additional locations were obtained from
topographic maps. The sample...
Surface and subsurface data from the Sulaiman thrust belt show that nearly all
the 10 km thick sequence of dominantly platform (>7 km) and molasse strata is detached
at the deformation front. These strata thicken tectonically to a minimum of 20 km in the
hinterland of the Sulaiman fold belt...
More efficient methods are needed for the in-situ evaluation of mass transfer parameters which describe the movement of solutes through aquifer material. The objective of this study was to develop a method for estimating diffusion rate and capacity coefficients using a single-well, "push-pull" tracer test. The method consists of the...
Fault zones are potential paths for release of radioactive nuclides from radioactive-waste repositories in granitic rock. This research considers detailed maps of en echelon fault zones at two sites in southern Sweden, as a basis for analyses of how their internal geometry can influence groundwater flow and transport of radioactive...
Late Quaternary sediments in the Willamette Valley, Oregon, include a unit of chiefly silt and fine sand, the Willamette Silt Formation. Previous workers have (1) Assigned the Willamette Silt different ages which range from Sangamon interglacial to late Wisconsin glacial, (2) Proposed that the Willamette Silt was deposited in a...
Low-permeability geologic units may offer significant chemical and hydraulic protection of adjacent aquifers, and are important for managing groundwater quality, especially in areas with significant non-point source contamination. Nitrate in the Willamette Valley is attenuated across the Willamette Silt, a semi-confining unit overlying a regionally important aquifer. To quantify the...
The Bear Creek area is situated at the boundry between the Basin and Range Province, Deschutes Basin and Blue Mountains Province. It contains rock units representing most of the Cenozoic geologic column. The major rock units exposed are the Clarno Formation, John Day Formation, Columbia River Basalt Group, Deschutes Formation...
The western Taylor Park area covers about 65 square
miles on the western flank of the Sawatch Range. It is
underlain chiefly by Precambrian rocks, partially covered
on the east by glacial debris and overlapped on the west
and south by Paleozoic sedimentary rocks.
The Precambrian rocks include a group...
The Salt Range is clearly the active participant in the scenario of the progressive southward migration of the Himalayan thrust front. It extends approximately 180 km ENE along strike and is underlain by salt. This is manifested by its very narrow (<1°) cross-sectional taper and great (150 km) width. Integration...
Groundwater nitrate contamination is a well-documented issue in the Southern Willamette Valley (SWV) of Oregon, as a Groundwater Management Area (GWMA) has recently been declared. As a GWMA, groundwater nitrate monitoring must occur until regional concentrations are below 7 mg/L NO3-N. However, the presence of temporal variability can make it...
Deposition of the Middle Devonian part of the Denay Limestone
and Bay State Dolomite in the northern Antelope Range and Fish
Creek Range, respectively, took place on and in front of a carbonate
platform with a lime sand shoal at the shelf edge. In the Givetian part
of the Denay...
This multidisciplinary study integrates remote sensing, stratigraphy, siliciclastic and carbonate sedimentology, tectonics, and petrography of the Nisai, Khojak and Sharankar Formations to reveal the Paleogene depositional, diagenetic and deformational history of the Katawaz Basin.
Study of Landsat Thematic Mapper (TM) digital data shows that maximum discrimination of different rocks is...
The Greenhorn Mountains contain a tectonic ally disrupted
ophiolite and both arc-derived and pelagic sediments. Age of major
sedimentary units within and bordering the thesis area is Early
Permian, based upon dates of conodonts and fusulinids from contemporaneous
but allocthanous limestones. Sediments near the south
boundary of the thesis area...