نتایج جستجو برای: zircon morphology

تعداد نتایج: 149157  

2010
AXEL K. SCHMITT FLORIAN WETZEL KARI M. COOPER HAIBO ZOU

Uranium-series dating of carbonatitic ejecta clasts constrains the crystallization and differentiation timescales of the Laacher See volcano, which erupted 6·3 km of magma (dense rock equivalent) during one of the largest Late Quaternary eruptions in Central Europe. Carbonatites form a distinct population among plutonic ejecta that are present in the middle and late erupted Laacher See tephra. ...

2002
J. B. THOMAS R. J. BODNAR N. SHIMIZU A. K. SINHA

Partition coefficients (DM) for rare earth elements (REE) (La, Ce, Nd, Sm, Dy, Er and Yb) and other trace elements (Ba, Rb, B, Sr, Ti, Y and Nb) between zircon and melt have been calculated from secondary ion mass spectrometric (SIMS) analyses of zircon/melt inclusion pairs. The melt inclusion-mineral (MIM) technique shows that DREE increase in compatibility with increasing atomic number, simil...

2014
C. A. Crow K. D. McKeegan D. E. Moser

Introduction: Zircon is a late stage accessory mineral that incorporates radiogenic parents such as uranium and thorium, while preferentially excluding their daughter product lead, allowing for precise U-Pb and Pb-Pb ages to be determined for individual grains [1]. Zircons also incorporate other trace elements such as the rare earth elements (REEs) and titanium, which can reflect the compositio...

2004
Marcus Wigand Axel K. Schmitt Robert B. Trumbull Igor M. Villa Rolf Emmermann

The Erongo subvolcanic center in Namibia is the largest composite, bimodal complex in the Mesozoic Etendeka igneous province of Namibia. This study of 40Ar/39Ar and high spatial resolution U^Pb zircon dating demonstrates that emplacement of the various igneous units at Erongo took place within a time span equivalent to or shorter than geochronologically resolvable age differences (ca. 2 Ma), an...

2003
Marcus Wigand Axel K. Schmitt Robert B. Trumbull Igor M. Villa Rolf Emmermann

The Erongo subvolcanic center in Namibia is the largest composite, bimodal complex in the Mesozoic Etendeka igneous province of Namibia. This study of 40Ar/39Ar and high spatial resolution U^Pb zircon dating demonstrates that emplacement of the various igneous units at Erongo took place within a time span equivalent to or shorter than geochronologically resolvable age differences (ca. 2 Ma), an...

Journal: :Earth Surface Processes and Landforms 2021

U–Pb dating of detrital zircons (DZ) in Quaternary slope deposits (cover beds) and examination the surface structure single zircon grains may enable reconstruction provenance their aeolian components help to reconstruct sedimentary palaeo-transportation cascades. We distinguish several layers using a palaeosol-supported sequence-stratigraphic approach. In pilot study, we demonstrate usability e...

Journal: :iranian journal of science and technology (sciences) 2014
b. keshavarzi

loess and loess-like deposits cover large areas of golestan province of iran, a well-known region in the world for its high incidence rate of esophageal cancer (ec). despite numerous published works on the possible contributing factors for the observed high incidence rate, very little attention has been given so far to a possible link between the mineralogy of loess deposits in the region and e...

2008
J. B. Saleeby

Cretaceous plutonic rocks of the southern Sierra Nevada batholith between latitudes 35.5°N and 36°N lie in a strategic position that physically links shallow, subvolcanic levels of the batholith to lower-crustal (~35 km deep) batholithic rocks. This region preserves an oblique crustal section through the southern Sierra Nevada batholith. Prior studies have produced large U/Pb zircon data sets f...

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