Results 341 to 350 of about 668,632 (409)

U-Pb dating of a speleothem of Quaternary age

Geochimica et Cosmochimica Acta, 1998
We demonstrate that U-Pb dating is a promising method for secondary carbonate materials of Quaternary age and older by obtaining a 206Pb∗/238U age for a speleothem with high U (>10 μg g−1) and very low Pb (
Richards, DA, Bottrell, SH, Cliff, RA, Strohle, K, Rowe, PJ   +4 more
openaire   +1 more source

Zircon UPb ages of Guyana greenstone-gneiss terrane

Precambrian Research, 1982
Abstract Isotopic UPb studies of zircons collected from weathered metagreywackes of the Barama-Mazaruni Supergroup of northern Guyana, South America, demonstrate an age of origin of ca. 2250 Ma. This is the best estimate for the age of the associated metavolcanic rocks.
Allan K. Gibbs, William J. Olszewski
openaire   +1 more source

Zircon U-Pb ages for the Early Cambrian time-scale

Journal of the Geological Society, 1992
Single zircons from two Early Cambrian volcanic horizons have been analysed using the SHRIMP ion microprobe. Full details of the analytical procedures and data reduction are given. Zircons from tuff within the Lie de Vin Formation, near Tiout, Morocco, show little spread in U-Pb age and have a mean value of 521 ± 7 Ma (2σ).
Compston, W., Williams, I. S., Kirschvink, J. L., Zichao, Zhang, Guogan, Ma   +4 more
openaire   +2 more sources

A minimum UPb age for Siberian flood-basalt volcanism

Geochimica et Cosmochimica Acta, 1996
Abstract Establishing an accurate and precise age for Siberian flood-basalt volcanism is of great importance in evaluating causes for the unequaled mass extinction of flora and fauna at the Permian-Triassic boundary. We report a new, minimum UPb age obtained from zircon and baddeleyite from the mineralized Noril'sk I intrusion that cuts the lower ...
S.L. Kamo, G.K. Czamanske, T.E. Krogh
openaire   +1 more source

Decay constant errors in U–Pb concordia-intercept ages

Chemical Geology, 2000
Abstract Although almost universally ignored, the effect of errors in the uranium decay-constants on U–Pb concordia-intercept ages (and Pb–Pb ages) are significant, and not equivalent to those of simple U–Pb ages. Equations are derived for concordia-intercept age-errors that take decay-constant errors into account.
openaire   +1 more source

U–Pb zircon ages for the Rice Lake area, southeastern Manitoba

Canadian Journal of Earth Sciences, 1989
The Archean Rice Lake greenstone belt in southeastern Manitoba is made up of mafic to felsic volcanic rocks and associated intrusive and metasedimentary rocks. The belt is flanked to the north by the Wanipigow River granitic complex and to the south by the Manigotagan gneissic belt.
A. Turek, R. Keller, W. R. Van Schmus, W. Weber   +3 more
openaire   +1 more source

Precambrian U-Pb zircon ages from Western Galicia(NW Spain)

Earth-Science Reviews, 1980
Abstract Zircon and monazite U-Pb ages are reported from two orthogneiss samples and one paragneiss from western Galicia. The three investigated suites of zircons reveal upper intercept ages of 2.2–2.5 Ga and lower intercept ages of about 470 Ma. The discordia pattern of the paragneiss is interpreted as resulting from lead loss of a detrital zircon ...
openaire   +1 more source

U-PB EMPLACEMENT AGES OF KANSAS LAMPROITES AND KIMBERLITES

Geological Society of America Abstracts with Programs, 2023
Isabella Lupini, Pamela D. Kempton, Andreas Möller, Claudia Adam   +3 more
openaire   +1 more source

UNMIXING DETRITAL ZIRCON U-PB AGE DISTRIBUTIONS

Geological Society of America Abstracts with Programs, 2017
Kurt E. Sundell, Joel E. Saylor
openaire   +1 more source

Genesis of zircon and its constraints on interpretation of U-Pb age

, 2004
Y. Wu, Yong‐Fei Zheng
semanticscholar   +1 more source