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Peter Popenoe

Publications and source records attributed to Peter Popenoe.

At least 55 records · Page 3Linked to original sources
USGS1976

Gravity studies in the Carolina slate belt near the Haile and Brewer mines, north-central South Carolina

The Bouguer gravity map of part of the Carolina slate belt near the Haile and Brewer mines in South Carolina shows anomalies related to rock units. The most conspicuous of the anomalies coincide with coarse-grained granitic plutons. Mathematically calculated models using an iterative three-dimensional solution of the gravity anomalies show that these plutons are steep-sided intrusive bodies that constrict at depth to small pipes or roots. The plutons are emplaced in and are probably largely confined to a unit of volcaniclastic rocks. The volcaniclastic rocks are probably 6,000 m to 10,000 m thick and similar in composition to those exposed in the vicinity of the plutons.

South Carolina↗
USGS1972

Principal facts for gravity stations in the area north of the Grand Canyon in Arizona

Observed gravity values, station location, terrain corrections, and Bouguer gravity data are provided in tabular form for approximately 610 gravity observations in northern Arizona. These data were used in preparation of - - Popenoe, Peter, 1968, Complete Bouguer gravity anomaly map of the area north of the Grand Canyon in Arizona: U.S. Geol. Survey open-file report.

Arizona↗
USGS1969

A geophysical study of North Park and the surrounding ranges, Colorado

A geophysical study in the North Park basin and surrounding mountains, Colorado illustrates the structural relationship of various sedimentary, metamorphic, and igneous rock units. Bouguer anomalies from 1330 gravity stations range from −210 mgal over Precambrian metamorphic rocks in the mountains to −260 mgal in the Walden syncline and —280 mgal in the North Park syncline. Steep gradients delineate a fault which strikes west-northwest along the north flank of the North Park syncline. Two models fitted to the gravity data show 1 to 2 km relief on this steeply dipping fault. Density contrasts between Precambrian metamorphic and igneous rocks produce anomalies of as much as 25-mgal amplitudes in the Park and Medicine Bow Ranges. A 30-km-long seismic refraction profile, parallel to the most negative Bouguer anomaly values in the North Park basin, shows velocities increasing from 2.5 to 3.4 km/sec within Tertiary rocks at depths ranging from 1.2 to 2.0 km. Mesozoic sedimentary rocks have a velocity of 4.0 to 4.5 km/sec, a very high velocity in view of the predominance of Upper Cretaceous rocks. Precambrian basement with a velocity of 6.25 km/sec underlies the profile at depths ranging from 3.5 to 4.5 km. Strong second arrivals across the profile, observed at distances of more than 14 km from the shotpoints and interpreted as SP reflections, verified the refraction model. An aeromagnetic survey shows numerous anomalies ranging from 100 to 200γ in the Park and Rabbit Ears Ranges and in the Never Summer Mountains, to 400γ in the Front Range, and to 1200γ over the Medicine Bow Range. Positive anomalies in the Park, Medicine Bow, and Front ranges overlie metamorphic rocks. Magnetic and gravity data suggest that the Never Summer Mountains are separated from the Front Range by a north-trending, steeply east-dipping reverse fault, extending beneath the Front Range along the Colorado River valley. The magnetic data indicate that this fault may connect with a possible fault that is parallel to the Laramie River valley. In the Rabbit Ears Range, a series of magnetic anomalies show that igneous rocks are present in the eastern part of the range. A northeast-trending positive magnetic anomaly, which is parallel to foliation trends reported in Precambrian rocks, extends from the Park Range across the North Park basin to the Medicine Bow Range. On the basis of this anomaly, the high seismic velocity of the Precambrian basement, and computed profiles fitted to the gravity and magnetic data, we infer that much of the basin is underlain by high-density metamorphic rock. As shown by gravity data, the deepest part of the basin is 2.7 km below sea level, resulting in a maximum relief of 6.7 km on the basement, relative to the Medicine Bow Range. A 25-mgal negative gravity anomaly and a zone of negative magnetic anomalies outline a large granitic intrusion in the Park Range, which probably extends northeast beneath the North Park basin and connects with granitic rocks in the Medicine Bow Range.

Colorado↗