The Hawaiian-Emperor bend has played a prominent yet controversial role in deciphering past Pacific plate motions and the tempo of plate motion change. New ages for volcanoes of the central and southern Emperor chain define large changes in volcanic migration rate with little associated change in the chain's trend, which suggests that the bend did not form by slowing of the Hawaiian hot spot. I...

Recent geochemical studies of uranium-thorium series disequilibrium in rocks from subduction zones require magmas to be transported through the mantle from just above the subducting slab to the surface in as little as approximately 30,000 years. We present a series of laboratory experiments that investigate the characteristic time scales and flow patterns of the diapiric upwelling model of subd...

The last 500 million years of the strontium-isotope record are shown to correlate significantly with the concurrent record of isotopic fractionation between inorganic and organic carbon after the effects of recycled sediment are removed from the strontium signal. The correlation is shown to result from the common dependence of both signals on weathering and magmatic processes. Because the long-...

The Yellowstone Plateau volcanic field is one of the largest centers exchange time to form zoned zircons is between a few hundred and a few thousand years, which reflects the residence time of lowO of rhyolitic magmatism on Earth. Major caldera-forming eruptions are followed by unusual lowO rhyolites. New oxygen isotope, magmas after formation and before eruption. petrologic and geochemical dat...

Introduction: It is well known that shergottites have a large variation of rare earth elements (REEs) abundance patterns and isotopic compositions. Jones [1] and Borg and Draper [2] suggest that light REEs (LREEs)-enriched shergottites resulted from mixing of a LREEs-enriched component with their parental magma. The LREEsenriched component is thought to be either Martian crust [1] or a KREEP-li...

Diverse explanations exist for the large-volume catastrophic eruptions that formed the Bishop Tuff of Long Valley in eastern California, the Bandelier Tuff in New Mexico, and the tuffs of Yellowstone, Montana, USA.These eruptions are among the largest on Earth within the last 2 Myr. A common factor in recently proposed petrogenetic scenarios for each system is multistage processing, in which a ...

Plio–Pleistocene (3.4–0.125 Ma) post-plateau magmatism in the Meseta del Lago Buenos Aires (MLBA; 46.7jS) in southern Patagonia is linked with the formation of asthenospheric slab windows due to ridge collision along the Andean margin f 6 Ma ago. MLBA post-plateau lavas are highly alkaline (43–49% SiO2; 5–8% Na2O+K2O), relatively primitive (6–10% MgO) mafic volcanics that have strong OIB-like g...

Despite an apparent north/south topographic dichotomy that formed >4.0 Ga, the young Martian meteorites (<2.4 Ga) and first-order remote sensing observations revealed a surface of Mars is uniformly basaltic. This simplistic vision has been challenged by discovery brecciated meteorite additional spacecraft data all point to presence alkaline igneous rocks, thereby demonstrating unexpected divers...