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Strontium-isotope stratigraphy of Enewetak Atoll Strontium-isotope stratigraphy of Enewetak Atoll

87Sr/86Sr ratios determined for samples from a 350 m core of Neogene lagoonal, shallow-water limestones from Enewetak Atoll display a remarkably informative trend. Like the recently published data for Deep Sea Drilling Project (DSDP) carbonates, 87Sr/86Sr at Enewetak increases monotonically but not smoothly from the early Miocene to the Pleistocene. The data show intervals of little or...
Authors
K.R. Ludwig, Robert B. Halley, Kathleen R. Simmons, Zell E. Peterman

U.S. Geological Survey deep seismic reflection profile across the Gulf of Maine U.S. Geological Survey deep seismic reflection profile across the Gulf of Maine

Deep seismic reflection and magnetic data suggest that the Gulf of Maine is underlain by four crustal blocks of differing reflection and magnetic character. Two of these blocks, the Gulf of Maine fault zone and adjacent central plutonic zone, can be correlated with Avalonian rocks in southern New England and New Brunswick. The boundary between them, the Fundy fault, projects onshore near...
Authors
Deborah R. Hutchinson, Kim D. Klitgord, Myung W. Lee, Anne M. Trehu

Geologic and hydrologic investigations of a potential nuclear waste disposal site at Yucca Mountain, southern Nevada Geologic and hydrologic investigations of a potential nuclear waste disposal site at Yucca Mountain, southern Nevada

Crustal velocity sections based on two seismic-refraction profiles are presented for the area west of Yucca Mountain, Nye County, Nevada. The Crater Flat profile is interpreted in terms of six velocity layers ranging from 1.5 to 6.1 km/s. Interpretation of the Beatty profile reveals an escarpment near the northeast edge of Bare Mountain, where Paleozoic rocks are probably down-faulted...

New trend- trigonometric model for interpolation and prediction of the geomagnetic field utilizing the new DGRF models New trend- trigonometric model for interpolation and prediction of the geomagnetic field utilizing the new DGRF models

At the IUGG Assembly at Vancouver during August 1987 new definitive geomagnetic reference field (DGRF) models to degree 10 for 1945, 1950, 1955, and 1960 were adopted by IAGA. Before these new DGRF models were accepted, the author developed a trend and trigonometric model (old trig model) based on the models IGRF 1945, IGRF 1950, IGRF 1955, IGRF 1960, DGRF 1965, DGRF 1970, DGRF 1975...
Authors
L.R. Alldredge

Range indices of geomagnetic activity Range indices of geomagnetic activity

The simplest index of geomagnetic activity is the range in nT from maximum to minimum value of the field in a given time interval. The hourly range R was recommended by IAGA for use at observatories at latitudes greater than 65??, but was superceded by AE. The most used geomagnetic index K is based on the range of activity in a 3 h interval corrected for the regular daily variation. In...
Authors
W.F. Stuart, A.W. Green

Data report for 1980-1981 seismic-refraction profiles in the western Mojave Desert, California Data report for 1980-1981 seismic-refraction profiles in the western Mojave Desert, California

During 1980 and 1981, the U.S. Geological Survey collected seismic refraction data in the western Mojave Desert (fig. 1). The seismic refraction data extends from north of the Garlock Fault, south through the Mojave Desert, and across the San Andreas Fault into the San Gabriel Mountains. This report describes and documents the recorded data, which was collected over three field sessions...
Authors
Reid N. Harris, A. W. Walter, Gary S. Fuis
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