Boulder Creek batholith, Colorado part II: Isotopic age of emplacement and morphology of zircon
Thomas W. Stern, George Phair, Marcia F. Newell
1971, Bulletin of the Geological Society of America (82) 1615-1633
Zircon separated from six rocks whose compositions spanned the range of differentiation in the Boulder Creek batholith yielded a “discordia” age of emplacement of 1725 m.y., close to the average PB207/Pb206 age 1720 m.y.) and indicating that the constituent rocks are cogenetic within approximately ± 20 m.y. Statistical studies show that...
Quaternary faulting in the eastern Alaska Range
D.H. Richter, N.A. Matson Jr.
1971, Bulletin of the Geological Society of America (82) 1529-1540
Quaternary faulting is well displayed along the Denali fault system and the recently recognized and related Totschunda fault system in the eastern Alaska Range. The principal movement on both fault systems is right-lateral strike-slip. Offset glacial features of Wisconsin age indicate minimum Holocene slip rates of 1.1 to 3.5 cm...
Boulder Creek batholith, Colorado part III: Fingerprinting discordant zircon ages in a complex intrusion
George Phair, Thomas W. Stern, David Gottfried
1971, Bulletin of the Geological Society of America (82) 1635-1655
The apparent ages (32 lead/alpha and 6 Pb206/U238) of zircon as plotted on an isochron map of the Boulder Creek batholith define the following pattern: (1) very high ages (1600 to 1900 m.y.) within the outermost border zone on the southwest, south, and southeast; (2) transitional high ages (1300 to...
Comparison of SLAR images and small-scale, low-sun aerial photographs
Malcolm M. Clark
1971, Bulletin of the Geological Society of America (82) 1735-1742
A comparison of side-looking airborne radar (SLAR) images and black and white aerial photos of similar scale and illumination of an area in the Mojave Desert of California shows that aerial photos yield far more information about geology than do SLAR images because of greater resolution, tonal range, and geometric...
An aeromagnetic and aeroradioactivity survey of Liberia, West Africa
John C. Behrendt, Cletus S. Wotorson
1971, Geophysics (36) 590-604
A 140,000 km aeromagnetic and total-count gamma radiometric survey was made over Liberia in 1967-68 along north-south lines spaced 0.8 km over land and 4 km over the continental shelf. The data approximately delineate the boundary between the Liberian (ca. 2700 m.y.) age province in...
Age of emplacement of Riley County, Kansas, kimberlites and a possible minimum age for the Dakota Sandstone
Douglas G. Brookins, Charles W. Naeser
1971, Bulletin of the Geological Society of America (82) 1723-1725
Field evidence suggests that the kimberlites of Riley County, Kansas, were emplaced into Lower Permian rocks in post-Dakota Sandstone time. The Dakota Sandstone in Kansas is thought to be earliest Late Cretaceous in age; thus the maximum age of emplacement of the kimberlites is approximately...
Structure and petrology of the alpine-type peridotite at Burro Mountain, California, U.S.A.
R. A. Loney, G. R. Himmelberg, R. G. Coleman
1971, Economic Geology (12) 245-309
The alpine-type peridotite at Burro Mountain is a partially serpentinized harzburgite-dunite body approximately 2 km in diameter. It lies in a chaotic mélange derived from the Franciscan Formation (Upper Jurassic to Upper Cretaceous) of the southern Coast Ranges of California. The peridotite is bounded on the east by a vertical fault...
A chemical study of serpentinization — Burro Mountain, California
R. G. Coleman, T. E. Keith
1971, Journal of Petrology (12) 311-328
Serpentinized dunites and harzburgites from the Burro Mountain peridotite show no change in the ratio of iron and magnesia to silica when compared with the same ratio for the unserpentinized equivalents. The mineral assemblage resulting from serpentinization consists of lizardite-chrysotile, brucite, and magnetite and is determined by the original...
Rapid separation of polychlorinated biphenyls from DDT and its analogues on silica gel
Diane Snyder, Robert E. Reinert
1971, Bulletin of Environmental Contamination and Toxicology (6) 385-390
Polychlorinated biphenyls (PCB's), which are used in industry worldwide (i), have been found as residues in numerous wildlife species (2-7). Because of the similarity in chemical characteristics, PCB compounds interfere with gas liquid chromatographic (GLC) analysis of certain chlorinated hydrocarbon insecticides (8). In the present study, we sought a rapid...
Origin and emplacement of the ultramafic rocks of the Emigrant Gap area, California
O.B. James
1971, Journal of Petrology (12) 523-560
The ultramafic bodies of the Emigrant Gap area are part of a mafic complex within a large composite pluton of the northern Sierra Nevada. The pluton was magmatically emplaced and is surrounded by an aureole of hornblende-hornfels facies rocks. Inclusions of country rock in ultramafic rock are of pyroxene-hornfels...
Magnetic anomalies over the continents
Isidore Zietz
1971, Eos Science News (52) 204-209
By far most of the magnetic coverage over continents has been made via aircraft. The obvious advantages of the airborne method over ground measurements are the speed and economy of the survey, the coverage of areas that are inaccessible on the ground, and the nature of the data, which are...
Water levels in carbonate rock terranes
H. E. LeGrand, V. T. Stringfield
1971, Groundwater (9) 4-10
Many subtle aspects of water levels in carbonate rocks need to be put in perspective even though hydrologists have recognized the fundamental value of characteristics of ground-water levels. The depth to the water table in carbonate rocks is controlled by local factors such as permeability and...
Ore fluids in the porphyry copper deposit at Copper Canyon, Nevada
J. Thomas Nash, Ted G. Theodore
1971, Economic Geology (66) 385-399
The large, low-grade copper and gold deposit at Copper Canyon, Lander County, Nevada, formed in the contact metasomatic environment adjacent to a shallow Tertiary intrusion. Vein and disseminated chalcopyrite-pyrite-pyrrhotite-arsenopyrite mineralization, with lesser amounts of gold, galena, sphalerite, marcasite, and siderite occur in the Upper Cambrian...
A Holocene ore body of copper oxides and carbonates at Ray, Arizona
C. H. Phillips, H. R. Cornwall, Meyer Rubin
1971, Economic Geology (66) 495-498
No abstract available....
Man-made earthquakes and earthquake prediction
J. H. Healy, L. C. Pakiser
1971, Eos Science News (52) 171-174
Convincing evidence that man can trigger earthquakes has been developed since the 1963–1967 report. The fact that man can start earthquakes has increased our understanding of earthquake mechanisms and reinforced our judgment that we are approaching the possibility of earthquake prediction.Traditionally, seismologists have avoided the subject of earthquake prediction because...
Mapping from space
Alden P. Colvocoresses
1971, Journal of the Surveying and Mapping Division (97) 125-132
Remote sensing of the earth promises to become an operational tool of the engineer and the scientist within the next few years. There are no real technical limits on the uses of data from space sensors. However, it is not practical to fly special missions, particularly in space, for each...
Primary and secondary sulfates at Goldfield, Nevada
M.L. Jensen, Roger P. Ashley, J. P. Albers
1971, Economic Geology (66) 618-626
High S-34 values for primary alunites (formed during hydrothermal phase) replacing plagioclase and groundmass of altered volcanic rocks, secondary alunite veins (formed during supergene alteration) with S-34 values near zero permil...
A new stratification of mourning dove call-count routes
L. H. Blankenship, A.B. Humphrey, Duncan MacDonald
1971, Journal of Wildlife Management (35) 319-326
The mourning dove (Zenaidura macroura) call-count survey is a nationwide audio-census of breeding mourning doves. Recent analyses of the call-count routes have utilized a stratification based upon physiographic regions of the United States. An analysis of 5 years of call-count data, based upon stratification using potential natural vegetation, has demonstrated...
Radiometric age (Late Ordovician) of the Quincy, Cape Ann, and Peabody Granites from eastern Massachusetts
Robert E. Zartman, Richard F. Marvin
1971, Bulletin of the Geological Society of America (82) 937-957
A geochronologic study of several intrusive bodies of alkalic granite from eastern Massachusetts yields the following radiometric ages (in millions of years).Rock unitAmphibole K-ArWhole-rock Rb-Sr isochron ...
Nationwide study of the streamflow data program
R. W. Carter, M. A. Benson
1971, Journal of the American Water Resources Association (7) 383-385
During 1970 the Geological Survey conducted a study to evaluate the surface-water data collection program. Objectives were formulated, specific goals were set, a massive analysis of available data was made to determine the extent to which the present system enables the goals to be met, alternatives...
Petrologic and geophysical nature of serpentinites
Robert G. Coleman
1971, Bulletin of the Geological Society of America (82) 897-917
Mineralogically, serpentinites consist predominantly of lizardite, clinochrysotile, and antigorite. Recent work has shown that these minerals are not polymorphs. Chrysotile is the only mineral recognized as a synthetic product in experimental studies of the system MgO-SiO2-H2O. Antigorite seems to be stable at higher temperatures than lizardite or chrysotile. The density...
Correlation of uranium, thorium, and potassium with aeroradioaetivity in the Berea Area, Virginia
S.K. Neuschel, C. M. Bunker, C.A. Busa
1971, Economic Geology (66) 302-308
In the Berea area, a small quartz monzonite pluton intrudes chlorite-actinolite schist and is overlapped by Coastal Plain sand and gravel deposits. A detailed aeroradioactivity survey of the area shows unusually high radioactivity (1,150 counts per second) over the quartz monzonite. A total of 22 auger samples was taken across...
Gravitational sliding and the foreland thrust and fold belt of the North American Cordillera: Reply
Melville Rhodes Mudge
1971, Bulletin of the Geological Society of America (82) 1139-1140
No abstract available....
Elevation-relief ratio, hypsometric integral, and geomorphic area-altitude analysis
Richard J. Pike, Stephen E. Wilson
1971, Bulletin of the Geological Society of America (82) 1079-1083
Mathematical proof establishes identity of hypsometric integral and elevation-relief ratio, two quantitative topographic descriptors developed independently of one another for entirely different purposes. Operationally, values of both measures are in excellent agreement for arbitrarily bounded topographic samples, as well as for low-order fluvial watersheds. By...
Gold content of natural waters in Colorado
Arthur W. Gosling, E. A. Jenne, T. T. Chao
1971, Economic Geology (66) 309-313
Neutron activation analysis of 67 samples of water draining from gold-barren and gold-enriched sedimentary, igneous, and metamorphic rocks of the Colorado Front Range reveals a relatively small range in total gold content (nondetectable to 150 nanograms per liter). "Solute" gold concentrations were generally higher than...
