Results 211 to 220 of about 5,193 (249)

Paleomagnetism of upper Precambrian to lower Paleozoic intrusive rocks from Colorado

Geological Society of America Bulletin, 1977
The paleomagnetism of the Iron Mountain–McClure Mountain alkalic intrusive complex in the northern Wet Mountains of Colorado has been investigated. Published radiometric ages for the complex, and for similar intrusive rocks nearby, range between 485 and 704 m.y.
R. B. FRENCH, D. H. ALEXANDER, R. VAN DER VOO   +2 more
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Lower Cambrian and Upper Precambrian Strata of Beaver Mountains, Utah

AAPG Bulletin, 1968
ABSTRACT Cambrian Prospect Mountain Quartzite and seven underlying units, tentatively considered Precambrian, are mapped in the Beaver Mountains. This concordant section begins where alluvium covers the base of the oldest unit and ends at the contact between the Prospect Mountain Quartzite and the overlying Pioche Shale.
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Origin of the Antietam Formation (Late Precambrian?--Lower Cambrian), Central Virginia

SEPM Journal of Sedimentary Research, 1970
ABSTRACT The Antietam Formation (Late Precambrian ?-Lower Cambrian) is a succession of quartz-rich clastics which occur in the upper part of the Chilhowee Group in the Central and Southern Appalachians. In central Virginia, the Antietam consists principally of orthoquartzitic and protoquartzitic sandstone.
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LOWER CAMBRIAN-PRECAMBRIAN SUCCESSION, WHITE-INYO MOUNTAINS, CALIFORNIA

Geological Society of America Bulletin, 1962
The approximately 21,000 feet of Lower Cambrian and Precambrian strata exposed in the White Mountains and Inyo Mountains, California, and vicinity is divided into eight formations. The upper four are new and constitute essentially what heretofore has been called the Silver Peak group, a term herein abandoned.
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Time, space and intensity relationships of the Precambrian and lower Palaeozoic metamorphisms of the Scottish Highlands

Geological Society, London, Special Publications, 1979
Summary Isotopic evidence suggests that a complex sequence of events, collectively known to us as the Morarian event, affected the Morar and Glenfinnan divisions of the Moine from 1000 to 750 Ma. A regional thermal anticline, with a minimum age of 750 Ma, extends north from Ardgour to northern Ross-shire: it probably extends southwards under ...
R. St J. Lambert, J. A. Winchester, J. G. Holland   +2 more
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THE STRATIGRAPHY OF THE UPPER PRECAMBRIAN AND LOWER CAMBRIAN IN SOUTH-EASTERN TUVA AND NORTHERN MONGOLIA

Russian Geology and Geophysics, 1992
A new stratigraphic scheme of the Upper Precambrian – Lower Cambrian in South-Eastern Tuva and Northern Mongolia is the result of lengthy integral investigations. Three regional subdivisions are discussed. These are Sangilen, Khugein (Upper Riphean) and Eastern Tuva (Vendian – Lower Cambrian) horizons enclosing lateral rows of local formations.
A. S. Gibsher, A. A. Terleev
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Strontium isotopic evidence relating to the evolution of the lower Precambrian granitic crust in Swaziland

Geology, 1976
Isotopic data for Swaziland Precambrian gneissic rocks, with Rb-Sr whole-rock ages in the range from 3,400 to 3,100 m.y., lie on a steep initial 87 Sr/ 86 Sr ratio versus time development line that intersects the basalt development line (or region) at about 3500 m.y. B.P.
R. D. Davies, H. L. Allsopp
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GEOCHEMISTRY OF THE UPPER PRECAMBRIAN AND LOWER CAMBRIAN BLACK SHALES FROM THE PHJONNAM DEPRESSION

Russian Geology and Geophysics, 1991
Thirty two samples from the Upper Precambrian and Lower Cambrian deposits of the Phjonnam depression, Sino-Korean Shield, have been analyzed for 43 chemical elements by X-ray fluorescence, atomic-absorption and instrumental neutron-activation methods. Organic carbon in black shales was established to be accompanied by the same elements as in sapropelic
V. M. Gavshin, N. A. Sozinov
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Nature and classification of microfossils of plant origin from Precambrian and lower Paleozoic

International Geology Review, 1965
A general consolidation of data relating to reports of Precambrian and lower Paleozoic spores of land plants and hystrichosphaers is presented. Emphasis is placed on the necessity of establishing clear and objective means of separating and classifying these organic remains. Their value lies in the theoretical interpretation of the origin of land plants
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Stratigraphy and Correlation of Basal Sections of the Lower Precambrian of the Southern Part of the Siberian Craton

Stratigraphy and Geological Correlation
For the southern part of the Siberian Craton, the geological and geochronological characteristics of the reference sections of six stratoregions of the Lower Precambrian are given. For the first time, their correlation was carried out, which served as the basis for the refined author’s regional stratigraphic scheme of the region.
Yu. B. Bogdanov, S. A. Anisimova
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