The isotopic thermochronological study included the U–Pb (SHRIMP) and fission-track dating of zircon and fission-track and (U–Th)–He dating of apatite from syenite intrusions cropping out in the eastern slope of the Sredinnyi Range of Kamchatka. The emplacement time of the intrusion was determined, and its exhumation velocity was evaluated. According to U–Pb (SHRIMP) zircon dating, the age of s...

We present an oxygen isotope and petrologic study of four voluminous, zoned ash-flow sheets of the Southwestern Nevada Volcanic Field (SWNVF): Topopah Spring (TS, .1200 km3, 12.8 Ma), Tiva Canyon (TC, 1000 km3, 12.7 Ma), Rainier Mesa (RM, 1200 km3, 11.6 Ma), and Ammonia Tanks (AT, 900 km3, 11.45 Ma). The d18O values of quartz, sanidine, sphene, magnetite, and zircons in rhyolites and latites of...

We report the results of an experimental calibration of oxygen isotope fractionation between quartz and zircon. Data were collected from 700 to 1000 C, 10–20 kbar, and in some experiments the oxygen fugacity was buffered at the fayalite–magnetite–quartz equilibrium. Oxygen isotope fractionation shows no clear dependence on oxygen fugacity or pressure. Unexpectedly, some high-temperature data (9...

The catastrophic disruption of the L chondrite parent body in the asteroid belt c. 470 Ma initiated a prolonged meteorite bombardment of Earth that started in the Ordovician and continues today. Abundant L chondrite meteorites in Middle Ordovician strata have been interpreted to be the consequence of the asteroid breakup event. Here we report a zircon U-Pb date of 467.50±0.28 Ma from a distinct...

A process is described which involves infiltration of aluminum nitrate into partially sintered (porous) zircon bodies. Infiltration kinetics were studied using infiltration curves with two distinct regions. The final infiltrated samples were sintered at 1600 °C for 2 h and yielded specimens containing the tetragonal zirconia.The experimental results show that in spite of the similar porosity of...

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. ...

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...

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...

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...

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...