Gravity and seismic data obtained by the geophysical group at
Oregon State University on the R/V YAQUINA during 1969, 1971, and
1973 plus other available data over the area just west of Nicaragua
and Costa Rica indicate the tectonic complexity of the region. Gravity
measurements show negative free-air anomalies over...
A free-air gravity anomaly map of the area between 10°-17°N and
90°-101°W shows distinctive positive and negative anomalies which
parallel the Tehuatepec Ridge. The positive anomaly approximately
overlies the topographic expression of the ridge. On the wide continental
shelf southeast of the Gulf of Tehuantepec a positive gravity
Magnetic, gravity and bathymetry data were collected on an extended
cruise of the R/V Yaquina in 1969. The last set of data was obtained
from those track lines leaving the Panama Basin. The area
covered is mainly the Cocos plate (Molnar and Sykes, 1969). The data
is analyzed and compared...
A zone of diffuse deformation -600 km-wide extending from northern California to Washington has developed resulting from the oblique subduction of the Juan de Fuca plate beneath North America, and the northwestward migration of the Pacific plate. This zone is marked by a change in structural style from transtension in...
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...
Ore deposits of the Butte district formed at ca. 66 to 62 Ma within a host rock of Butte Quartz Monzonite (ca. 76 Ma). Deposition of the Lowland Creek Volcanics Formation (ca. 53 to 50 Ma) on top of the Butte Quartz Monzonite and its ores, followed a period of...
Approximately 23 square miles of the east-central part
of the Tendoy Range are included in the thesis area which
lies three miles west of Dell, Montana.
Rocks ranging in age from Late Mississippian to Recent
are exposed in the study area. The upper Paleozoic section
includes approximately 4,200 feet (1,281...
The Grant Range, in east-central Nevada, is a
north-east trending range bounded on the west by a
west-dipping normal fault system. Rocks within the range
record a complex polyphase Mesozoic ductile
compressional and Cenozoic brittle extensional
deformational history. The northwestern Grant Range
exposes deformed, regionally metamorphosed and
unmetamorphosed, Cambrian to...
The Sulaiman foldbelt is an active and conspicuous tectonic
feature on the northwestern margin of the Indo-Pakistani plate.
Seismic reflection data have been combined with surface geological
mapping and drillhole data to interpret the structural style and
tectonic shortening of the eastern Sulaiman foldbelt and its adjacent
foredeep. The data...
The Whittier fault forms the central part of a fault system extending
from the East Montebello fault at Whittier Narrows to the Elsinore fault,
which is traced as far as the Mexican border. The Whittier fault forms a
restraining bend in this fault system, resulting in uplift of the Puente...