Results 181 to 190 of about 2,046 (219)

Tectonic Implications of U-Pb Zircon Ages of the Himalayan Orogenic Belt in Nepal

Science, 2000
Metasedimentary rocks of the Greater Himalaya are traditionally viewed as Indian shield basement that has been thrust southward onto Lesser Himalayan sedimentary rocks during the Cenozoic collision of India and Eurasia. Ages determined from radioactive decay of uranium to lead in zircon grains from Nepal suggest that Greater Himalayan protoliths were ...
, DeCelles, , Gehrels, , Quade, , LaReau, , Spurlin   +4 more
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Determination of U-Pb ages of zircons by direct measurement of the 210Pb/206Pb ratio

Chemical Geology, 1993
Abstract Precise measurements of the 210Pb/206Pb ratio in zircons permits, for the first time, the determination of complete U-Pb ages by measurement of Pb isotopes only, without determination of the U-Pb ratio by isotope dilution. The 238U daughter isotope 210Pb is generally in radioactive equilibrium with 238U; however, the very short half-life of ...
Wendt, I., Wendt, I., Tuttas, D.
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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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Age constraint on Burmese amber based on U–Pb dating of zircons

Cretaceous Research, 2012
Amber from northern Myanmar has been commercially exploited for millennia, and it also preserves the most diverse palaeobiota among the worlds' seven major deposits of Cretaceous amber. Recent estimated ages vary from Albian to Cenomanian, based on palynology, an ammonoid, and Mesozoic insect taxa preserved within the amber. The burmite-bearing rock is
Guanghai Shi, David A. Grimaldi, George E. Harlow, Jing Wang, Jun Wang, Mengchu Yang, Weiyan Lei, Qiuli Li, Xianhua Li   +8 more
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UPb ages of zircons: A basic examination of error propagation

Chemical Geology: Isotope Geoscience section, 1987
Abstract The past three decades have seen a remarkable development and expansion of the UPb dating technique as applied to zircons. It is regrettable, however, that many otherwise sophisticated zircon studies lack even the most rudimentary error analysis for individual data points, despite the availability of published error programs, while others ...
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U-Pb zircon age of the Rostberget W-occurrence, northern Sweden

Geologiska Föreningen i Stockholm Förhandlingar, 1989
Anomalously U-rich granites of the so-called Revsund type, associated with W- and Sn-enrichments, occur in the Gunnarn area close to Storuman in northern Sweden.
Kjell Billström, Björn Öhlander
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Ion microprobe zircon U–Pb age and geochemistry of the Myanmar jadeitite

Journal of the Geological Society, 2008
Combined geochemistry and geochronology of the Myanmar jadeitite were determined. Bulk-rock trace element compositions display U-shaped REE patterns with pronounced positive Eu anomalies. The total REE abundances are very low, less than half chondritic, and the high field strength elements and some large ion lithophile elements are moderately enriched.
GUANGHAI SHI, WENYUAN CUI, SHUMIN CAO, NENG JIANG, PING JIAN, DUNYI LIU, LAICHENG MIAO, BINGBING CHU   +7 more
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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
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New U–Pb zircon ages and the duration and division of Devonian time

Earth and Planetary Science Letters, 1998
Newly determined U‐Pb zircon ages of volcanic ashes closely tied to biostratigraphic zones are used to revise the Devonian time-scale. They are: (1) 417:6 1:0 Ma for an ash within the conodont zone of Icriodus woschmidti=I. w. hesperius (early Lochkovian); (2) 408:3 1:9 Ma for an ash of early Emsian age correlated with the conodont zones of Po ...
R.D Tucker, D.C Bradley, C.A Ver Straeten, A.G Harris, J.R Ebert, S.R McCutcheon   +5 more
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U-Pb Zircon Age of Precambrian Basement Gneiss of South Korea

Geological Society of America Bulletin, 1973
A U-Pb zircon age of 2,150 m.y. confirms the middle Precambrian age for basement gneiss of South Korea.
H. E. GAUDETTE, P. M. HURLEY
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