gomish-tappeh zn-pb-cu (ag) deposit is located 90 km southwest of zanjan, in northwestern part of urumieh-dokhtar volcano-plutonic zone. exposed rocks at the area include oligo-miocene volcano-sedimentary and sedimentary sequences as well as pliocene volcano-plutonic sequence (andesite porphyry dykes, dacitic subvolcanic dome and rhyodacitic volcanics). alteration in the deposit developed as si...

The Indian Peak volcanic field is representative of the more than 50,000 km3 of ashflow tuff and tens of calderas in the Great Basin that formed during the Oligocene-early Miocene "ignimbrite flareup" in southwestern North America. The field formed about 32 to 27 Ma in the southeastern Great Basin and consists of the centrally positioned I n d i Peak caldera complex and a surrounding blanket of...

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...