Results 221 to 230 of about 50,766 (267)

Neurocognitive consequences of occupational heavy metal exposure among electronic waste sorting workers in Thailand. [PDF]

Narra J
Harasarn K, Keawkaen P, Thetkathuek A.
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U-Pb AGE OF THE CHATTANOOGA SHALE

Geological Society of America Bulletin, 1960
An attempt was made to date the upper black unit of the Gassaway member of the Chattanooga shale which carries the maximum U/Pb ratio. Three samples were analyzed by isotopic dilution techniques. The U238-Pb206 ages on all 3 samples agreed within their experimental errors. The average of the two samples with reasonably small errors gave an apparent age
J. C. COBB, J. L. KULP
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Interpretation of discordant U‐Pb zircon ages: An evaluation

Journal of Metamorphic Geology, 1997
The most widely used technique for the determination of high precision mineral growth ages in igneous and metamorphic rocks is dating of zircons with the U‐Pb method. The interpretation of these ages, particularly in metamorphic settings, is hampered by an incomplete understanding of the common phenomenon of partial Pb‐loss in zircon.
Mezger, Klaus, KROGSTAD, E. J.
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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
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U-Pb age of the Baltoro granite, northwest Himalaya, and implications for monazite U-Pb systematics

Geology, 1989
The Baltoro granite is a major late- to post-tectonic plutonic phase of the Karakoram batholith of the northwest Himalaya in northern Pakistan. U-Pb zircon analyses indicate both emplacement at 21.0 ±0.5 Ma and significant Precambrian zircon inheritance.
Randall R. Parrish, Rein Tirrul
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U-Pb Ages from the Neoproterozoic Doushantuo Formation, China

Science, 2005
U-Pb zircon dates from volcanic ash beds within the Doushantuo Formation (China) indicate that its deposition occurred between 635 and 551 million years ago. The base records termination of the global-scale Marinoan glaciation and is coeval with similar dated rocks from Namibia, indicating synchronous deglaciation.
Daniel, Condon, Maoyan, Zhu, Samuel, Bowring, Wei, Wang, Aihua, Yang, Yugan, Jin   +5 more
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U‐Pb age of the Yxsjöberg Tungsten‐Skarn deposit, Sweden

GFF, 1994
Abstract The Yxsjoberg scheelite‐skam deposit of western Bergslagen (south‐central Sweden) formed in Palaeoproterozoic time when aqueous fluids migrating along lithologic discontinuities replaced limestones in acid volcanic rocks. The age of the mineralization and, thus, the source of the fluids are controversial.
Romer, R., Öhlander, B.
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U‐Pb SIMS ages of Apollo 14 zircon: Identifying distinct magmatic episodes

Meteoritics & Planetary Science, 2019
AbstractU‐Pb ages of zircon in four different Apollo 14 breccias (14305, 14306, 14314, and 14321) were obtained by secondary ion mass spectrometry. Some of the analyzed grains occur as cogenetic, poikilitic zircon grains in lithic clasts, revealing magmatic events at ~4286 Ma, ~4200–4220 Ma, and ~4150 Ma.
F. Thiessen, A. A. Nemchin, J. F. Snape, M. J. Whitehouse   +3 more
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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
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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
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