نتایج جستجو برای: zircon

تعداد نتایج: 3386  

2015
I. Metcalfe R. S. Nicoll M. Schmitz J. Crowley

Twenty-eight new high-precision Chemical Abrasion Isotope Dilution Thermal Ionisation Mass Spectrometry U-Pb zircon dates for tuffs in the Sydney and Bowen Basins are reported. Based on these new dates, the Guadalupian-Lopingian/Capitanian-Wuchiapingian boundary This is an author-produced, peer-reviewed version of this article. The final, definitive version of this document can be found online ...

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In this study it was tried to investigate on the effective parameters of the formation and increasing tetragonal zirconia phase in reaction sintering of alumina and zircon.  In this way, alumina and zircon powders were mixed by the ratio of 85 to 15 wt.% and sintered at different conditions. Sintering temperature (1500-1650˚C), furnace type (conventional and microwave) and the milling time of r...

احدنژاد, وحید, رسولی, جمال, قربانی, منصور,

The Jebale-Barez plutonic complex (JBPC) is composed of granitic rocks and located in the E-NE of Jiroft in the SE part of Kerman Province. It is mainly consists of granodiorite but alkali-feldspar granite, granite, quartz-syenite and quartz-diorite can be observed in the region. The U-Th ratio in granitoids was used for petrogenetic studies. In this point of view, the JBPC has U-Th ratio lower...

2010
William R. Dickinson George E. Gehrels Robert J. Stern

641 Geosphere; October 2010; v. 6; no. 5; p. 641–662; doi: 10.1130/GES00532.1; 12 fi gures; 4 tables; 1 supplemental fi le. 1Supplemental File 1. Excel fi le of U-Pb (zircon) geochronologic analyses by laser-ablation multicollector ICP mass spectrometry. If you are viewing the PDF of this paper or reading it offl ine, please visit http://dx.doi.org/10.1130/GES00532.S1 or the fulltext article on...

2006
R. M. Flowers S. A. Bowring P. W. Reiners

Zircon and apatite crystals from the western Canadian shield yield (U-Th)/He dates that are the oldest yet reported for terrestrial rocks. Zircon dates from 1.73 to 1.58 Ga are consistent with independent geological and thermochronological constraints, and indicate that the rocks were at temperatures 180 C and crustal depths 7–10 km since ca. 1.7 Ga. Apatite dates from 0.95 to 0.55 Ga suggest r...

2011
P. Skyttä

New U-Th-Pb zircon data (SIMS) from three intrusive phases of the Palaeoproterozoic Viterliden intrusion in the western Skellefte District, central Fennoscandian Shield, dates igneous emplacement in a narrow time interval at about 1.89 Ga. A locally occurring quartz-plagioclase porphyritic tonalite, here dated at 1889± 3 Ma, is considered the youngest of the intrusive units, based on the new ag...

2010
M. Bernet

The European Alps are a mountain belt that is characterized by a series of discrete orogenic events, which have long been recognized. Despite the inherent episodic nature of orogenic evolution, the Alps have been continuously exhumed, mainly by erosion, but also by normal faulting. Since continental collision started in the late Eocene/Early Oligocene evidence for ongoing erosional exhumation h...

2016
Weitao Wang Peizhen Zhang Jingxing Yu Yizhou Wang Dewen Zheng Wenjun Zheng Huiping Zhang Jianzhang Pang

The Cenozoic basins and ranges form the high topography of the northeastern Tibet that resulted from the India-Eurasia collision. Sedimentary rocks in the basins provide direct insight into the exhumation history of the ranges and the tectonic processes that led to the northeastward growth of the Tibetan Plateau. In this study, we analyzed and compared detrital zircon U-Pb ages from sands of mo...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2007
J G Liou R Y Zhang W G Ernst

Mantle-derived garnet peridotites are a minor component in many very high-pressure metamorphic terranes that formed during continental subduction and collision. Some of these mantle rocks contain trace amounts of zircon and micrometer-sized inclusions. The constituent minerals exhibit pre- and postsubduction microstructures, including polymorphic transformation and mineral exsolution. Experimen...

2004
Birger Rasmussen Ian R. Fletcher Stefan Bengtson Neal J. McNaughton

The Stirling Range Formation in southwestern Australia contains discoidal fossils previously linked to the late Neoproterozoic Ediacaran biota and possible trace fossils interpreted to have been made by vermiform, mucus-producing, motile organisms. The age of the sedimentary succession was recently reported to be between 2.0 and 1.2 billion years old, based on U–Pb geochronology of detrital zir...

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