The Quaternary Zarloukh Bentonite -Tuff (ZBT) deposit occurs within the Hemrin South Mountain, northern Iraq. ZBT as depression-filling exposed on erosional surface of siliciclastic Pliocene Muqdadiya Formation and covered by an overburden recent sediments. thickness studied industrial bentonite bed is ~80-100 cm, occurring at bottom these depressions, ~3-4 m thick bedded volcanic tuff, which a...

To evaluate the potential of (U–Th)/He geochronometry and thermochronometry of zircon, we measured He diffusion characteristics in zircons from a range of quickly and slowly cooled samples, (U–Th)/He ages of zircons from the quickly cooled Fish Canyon Tuff, and age-paleodepth relationships for samples from 15 to 18 km thick crustal section of the Gold Butte block, Nevada. (U–Th)/He ages of zirc...

A voluminous ([600 km) and long-lived (*520–75 ka) phase of rhyolitic eruptions followed collapse of the Yellowstone caldera 640 ka. Whether these eruptions represent a dying cycle, or the growth of a new magma chamber, remains an important question. We use new U–Th zircon ages and dO values determined by ion microprobe, and sanidine Pb isotope ratios determined by laser ablation, to investigat...

INTRODUCTION Approximately 160,000 yr ago, one of the largest Quaternary explosive volcanic eruptions of the Mediterranean basin occurred just offshore of the island of Kos (Greece), resulting in ~60 km of volcanic ash and pumice emplaced as pyroclastic fall and fl ow deposits over an area >2000 km (Keller, 1969; Allen, 2001; Fig. 1). In comparison to the 3500 yr B.P. Minoan eruption, which cre...

Integrated testing of the important components of a glass waste form waste package has been performed in order to gain a better understanding of the processes of radionuclide release and transport in the near field environment. Based upon an interpretation of the depth of penetration of hydrogen in reacted SRL-165 glass we have modeled the radionuclide release from the glass as a combined proce...

As part of the characterization of Yucca Mountain, Nev., as a potential repository for high-level nuclear waste, volcanic tuff was analyzed for microbial abundance and activity. Tuff was collected aseptically from nine sites along a tunnel in Yucca Mountain. Microbial abundance was generally low: direct microscopic cell counts were near detection limits at all sites (3.2 x 10(sup4) to 2.0 x 10(...