Latest Igneous rocks Stories
A new study provides "incontrovertible evidence" that the volcanic super-eruption of Toba on the island of Sumatra about 73,000 years ago deforested much of central India, some 3,000 miles from the epicenter, researchers report.The volcano ejected an estimated 800 cubic kilometers of ash into the atmosphere, leaving a crater (now the world's largest volcanic lake) that is 100 kilometers long and 35 kilometers wide. Ash from the event has been found in India, the Indian Ocean, the...
Surface deformation of 4 active volcanoes captured on InSAR underscore possibility for human hazard, potential of geothermal resourcesA team from the University of Miami, University of El Paso and University of Rochester have employed Interferometric Synthetic Aperture Radar (InSAR) images compiled over a decade to study volcanic activity in the African Rift. The study, published in the November issue of Geology, studies the section of the rift in Kenya."The Kenyan Rift volcanoes are...
Geologists Show that Seafloor Dynamics Are at Work in Splitting African ContinentIn 2005, a gigantic, 35-mile-long rift broke open the desert ground in Ethiopia. At the time, some geologists believed the rift was the beginning of a new ocean as two parts of the African continent pulled apart, but the claim was controversial.Now, scientists from several countries have confirmed that the volcanic processes at work beneath the Ethiopian rift are nearly identical to those at the bottom of the...
Plinian volcanic eruptions are notoriously destructive. These very powerful eruptions often occur after long periods of quiescence and are preceded by relatively short periods of seismic restiveness. Volcanoes that tend to show this kind of behavior include Mount Vesuvius in Italy, Mt. Pinatubo in the Philippines and Mt. St. Helens in the USA. Professor Donald Dingwell of Ludwig-Maximilians-Universität (LMU) in Munich, together with Professor Jonathan Castro of the University of Orléans...
U.S. scientists say they have used simulations to determine the atmosphere of an exoplanet discovered in February is hot enough to rain pebbles. Researchers at Washington University in St. Louis say their models show the exoplanet is close enough to its star that its day-face maintains a temperature of about 4,220 degrees Fahrenheit -- hot enough to vaporize rocks. The theoretical models suggest the planet has an atmosphere of the components of rock in gaseous form and lava or boiling oceans...
Worldwide, thousands of workers die every year from mining accidents, and instantaneous coal outbursts in underground mines are among the major killers. But although scientists have been investigating coal outbursts for more than 150 years, the precise mechanism is still unknown.New research by scientists at the University of Michigan and Peking University in Beijing, China, suggests that the outbursts occur through a process very similar to what happens during explosive volcanic eruptions....
Scientists have found the "Rosetta Stone" of supervolcanoes, those giant pockmarks in the Earth's surface produced by rare and massive explosive eruptions that rank among nature's most violent events. The eruptions produce devastation on a regional scale "” and possibly trigger climatic and environmental effects at a global scale.A fossil supervolcano has been discovered in the Italian Alps' Sesia Valley by a team led by James E. Quick, a geology professor at Southern Methodist...
 Scientists have placed high-tech "spiders" inside and around the mouth of Mount St. Helens, one of the most active volcanoes in the United States. Networks such as these could one day be used to respond rapidly to an impending eruption. On July 14, 2009, these spider pods were lowered by cable from a helicopter hovering about 100 feet up (30 meters) and gently put in hot spots inside and around the volcano crater."This project demonstrates that a low-cost sensor network...
When Alaska's Kasatochi Volcano erupted on Aug. 7, 2008, it virtually sterilized Kasatochi Island, covering the small Aleutian island with a layer of ash and other volcanic material several meters thick. The eruption also provided a rare research opportunity: the chance to see how an ecosystem develops from the very first species to colonize the island.Next week, a team of researchers organized by the U.S. Geological Survey and the U.S. Fish and Wildlife Service will visit Kasatochi to look...
U.S. scientists said they have determined the eruption of Indonesia's Toba volcano about 74,000 years ago triggered a decade-long severe winter. Previous studies suggested the massive eruption produced a 1,000-year episode of ice sheet advance, as well as a volcanic winter, which most likely would have drastically reduced the human population at the time. To investigate additional mechanisms that might have enhanced and extended the effects of the Toba eruption, Rutgers University Professor...
Latest Igneous rocks Reference Libraries
Biotite is a common phyllosilicate mineral that contains potassium, magnesium, iron and aluminium. It is sometimes called "iron mica" and is found in granitic rocks, gneisses, and schists. Like other mica minerals, biotite has a highly perfect basal cleavage, its flexible sheets easily flaking off. It has a hardness of 2.5 - 3, a specific gravity of 2.7 - 3.1, is colored greenish to brown or black, and can be transparent to opaque. Biotite is occasionally found in large sheets, especially in...
Diorite is a grey to dark grey intermediate intrusive igneous rock composed principally of plagioclase feldspar (typically andesine), hornblende, and/or pyroxene. Varieties deficient in hornblende and other dark minerals are called leucodiorite. It is often described as "salt and pepper" when composed largely of light-colored minerals randomly interspersed with dark minerals. When olivine and more iron-rich augite are present, the rock grades into ferrodiorite, which is transitional to...
Gabbro is a dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt. It is a plutonic rock, formed when molten magma is trapped beneath the Earth's surface and cools slowly into a hard, coarsely crystalline mass. It is dense, greenish or dark-colored and contains varied percentages of plagioclase feldspar, pyroxene, amphibole, and olivine (called olivine gabbro when olivine is present in large quantities). Quartz gabbros are also known to occur and are probably derived...
Peridotite is a dense, coarse grained ultrabasic rock, consisting mainly of the minerals olivine and pyroxene. Peridotite is also a group of mantle derived igneous rocks. They all are ultramafic or ultrabasic meaning they contain less than 45% silica and are high in iron and magnesium. Members of the peridotite family include: Dunite - predominately composed of olivine, with minor enstatite pyroxene and chromite. Harzburgite - composed of olivine, enstatite, and minor chromite....
Rhyolite is an igneous, volcanic (extrusive) rock, of felsic composition, with aphanitic to porphyritic texture. Mineral assembly is usually quartz, alkali feldspar and plagioclase (in a ratio > 1:2). Biotite and pyroxene are common accessory minerals. Rhyolite can be considered as the extrusive equivalent to the plutonic granite rock. Due to their high content of silica, rhyolite form highly viscous lavas. They can also occur as breccias or in volcanic necks and dikes. Like obsidian,...
