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CREATION ART

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  • Photobucket Songs of Earth's Creations. In an endless cycle of eons she creates and destroys masterpieces, reusing her building materials to create anew. From death comes life.Photobucket
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    Saturday, December 09, 2006

     

    PROLOGUE TO POSTS ON ANCIENT VULCANISM (Below)


    FLOOD BASALTS, MANTLE PLUMES & MASS EXTINCTIONS

    Flood Basalts

    The great continental flood-basalt eruptions of the geological past are the largest eruptions of lava on Earth, with known volumes of individual lava flows exceeding 2000 cubic kilometres. For comparison, the ongoing eruption of Kilauea volcano on Hawaii has produced just 1.5 cubic kilometres in 16 years! A series of these huge eruptions builds up a thick stack of basalt lava flows as shown in the photograph ...

    Columbia river basalts

    A stack of about 20 Columbia River Basalt lava flows in the canyon of the Grande Ronde River, Washington state, USA

    Each flow is 15-20m thick

    ... extending over areas of more than a million square kilometres. Flood basalts are one type of large igneous province (LIP) that characterise the Earth's surface and have been formed at various times in the geological past - some in a submarine environment and some on land (see LIP map below). Notable examples are the Siberian Traps and the Deccan Traps (trap is a Sanskrit word meaning 'step', referring to the step-like topography produced by the stacked layers of lava). The Columbia River province featured in the above photograph is minute in comparision to the size of these enormous outpourings of lava.

    Large igneous provinces of the world

    Global map

    Mantle Plumes

    Large igneous provinces are thought to be caused by the arrival of a mantle plume in the Earth's outermost layer, the lithosphere. The plumes are proposed to be richer in lighter elements and hotter than the surrounding mantle. As they rise, magma (liquid rock) is generated by partial melting of the plume material. The magma is injected into the lithosphere and erupted onto the Earth's surface to form huge basalt lava flows. The first few million years of a newly arrived mantle plume seem to be the most fertile in terms of magma production and flood basalts are therefore formed in a very short period of geological time.

    Plumes are thought to originate very deep in the Earth - perhaps at the core-mantle boundary for the larger ones and at a depth of about 600 km deep for the smaller ones - but they seem to be related to the breakup of continents (rifting), so there is some influence from global plate tectonic processes.

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    If there is a causal link between flood basalt events and mass extinctions, it may lie in the environmental impact of the gases released, because basalt eruptions are not particularly explosive. Several kinds of environmental effects have been suggested, including climatic cooling from sulphuric acid aerosols, greenhouse warming from CO2 and SO2 gases, and acid rain. Basaltic magmas are often very rich in dissolved sulphur, and sulphuric acid aerosols formed from sulphur volatiles (largely SO2) are injected into the stratosphere by convective plumes rising above volcanic vents and fissures.

    Indirect environmental effects include changes in ocean chemistry, circulation, and oxygenation, especially from basaltic volcanism associated with large submarine oceanic plateaus that may represent flood basalt eruptions in an oceanic environment.

    A major uncertainty is the nature and severity of the environmental effects of the eruptions and their potential impact on life. Although the correlation between some flood basalt episodes and extinctions may implicate volcanism in the extinctions, it is also possible that other factors lead to an apparent association. Flood basalt episodes have been attributed to mantle plume activity, and thus may represent one facet of a host of related global geological factors (eg, changes in sea-floor spreading rates, rifting events, increased tectonism and volcanism, sea-level variations) that tend to be correlated, and may be associated with unusual climatic and environmental fluctuations that could lead to significant faunal changes. It has also been suggested that a coincidence of both a large impact and a flood basalt eruption might be necessary in causing severe mass extinctions.

    http://www.geolsoc.org.uk/template.cfm?name=fbasalts (edited for length)

    If there is a causal link between flood basalt events and mass extinctions, it may lie in the environmental impact of the gases released, because basalt eruptions are not particularly explosive. Several kinds of environmental effects have been suggested, including climatic cooling from sulphuric acid aerosols, greenhouse warming from CO2 and SO2 gases, and acid rain. Basaltic magmas are often very rich in dissolved sulphur, and sulphuric acid aerosols formed from sulphur volatiles (largely SO2) are injected into the stratosphere by convective plumes rising above volcanic vents and fissures.

    Indirect environmental effects include changes in ocean chemistry, circulation, and oxygenation, especially from basaltic volcanism associated with large submarine oceanic plateaus that may represent flood basalt eruptions in an oceanic environment.

    A major uncertainty is the nature and severity of the environmental effects of the eruptions and their potential impact on life. Although the correlation between some flood basalt episodes and extinctions may implicate volcanism in the extinctions, it is also possible that other factors lead to an apparent association. Flood basalt episodes have been attributed to mantle plume activity, and thus may represent one facet of a host of related global geological factors (eg, changes in sea-floor spreading rates, rifting events, increased tectonism and volcanism, sea-level variations) that tend to be correlated, and may be associated with unusual climatic and environmental fluctuations that could lead to significant faunal changes. It has also been suggested that a coincidence of both a large impact and a flood basalt eruption might be necessary in causing severe mass extinctions.

    http://www.geolsoc.org.uk/template.cfm?name=fbasalts (edited for length)



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    The 5 Major Extinctions
    suffered by life on planet Earth (so far)


    Here are details of the five worst mass extinctions in Earth’s history and their possible causes, according to paleobiologist Doug Erwin of the Smithsonian Institution’s National Museum of Natural History. Erwin said estimates of extinction rates are from the late John J. Sepkoski at the University of Chicago:

    Cretaceous-Tertiary extinction, about 65 million years ago, probably caused or aggravated by impact of several-mile-wide asteroid that created the Chicxulub crater now hidden on the Yucatan Peninsula and beneath the Gulf of Mexico. Some argue for other causes, including gradual climate change or flood-like volcanic eruptions of basalt lava from India’s Deccan Traps. The extinction killed 16 percent of marine families, 47 percent of marine genera (the classification above species) and 18 percent of land vertebrate families, including the dinosaurs.

    End Triassic extinction, roughly 199 million to 214 million years ago, most likely caused by massive floods of lava erupting from the central Atlantic magmatic province -- an event that triggered the opening of the Atlantic Ocean. The volcanism may have led to deadly global warming. Rocks from the eruptions now are found in the eastern United States, eastern Brazil, North Africa and Spain. The death toll: 22 percent of marine families, 52 percent of marine genera. Vertebrate deaths are unclear.

    Permian-Triassic extinction, about 251 million years ago. Many scientists suspect a comet or asteroid impact, although direct evidence has not been found. Others believe the cause was flood volcanism from the Siberian Traps and related loss of oxygen in the seas. Still others believe the impact triggered the volcanism and also may have done so during the Cretaceous-Tertiary extinction. The Permian-Triassic catastrophe was Earth’s worst mass extinction, killing 95 percent of all species, 53 percent of marine families, 84 percent of marine genera and an estimated 70 percent of land species such as plants, insects and vertebrate animals.

    Late Devonian extinction, about 364 million years ago, cause unknown. It killed 22 percent of marine families and 57 percent of marine genera. Erwin said little is known about land organisms at the time.

    Ordovician-Silurian extinction, about 439 million years ago, caused by a drop in sea levels as glaciers formed, then by rising sea levels as glaciers melted. The toll: 25 percent of marine families and 60 percent of marine genera

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    Friday, December 08, 2006

     

    Columbian River Flood Basalts

    Province Idaho , Washington, Oregon

    http://volcano.und.edu/vwdocs/volc_images/north_america/crb.html

    Columbia River Flood Basalt Province, Idaho, Washington, Oregon, USA

    More Information

    General Overview


    The Grand Ronde Basalt of the Columbia River Basalt Group. Thick stacks of laterally extensive lava flows typify this flood basalt province. Photo by Thor Thordarson.


    Area covered by Columbia River flood basalts shown in gray. Dashed lines are dike swarms. The outer limits of the Chief Joseph dike swarm are marked by CJ (vents for the flows in the Imhaha, Grande Ronde, and Wanapum Formations and Saddle Mountains Basalt). The Grande Ronde (GR) and Cornucopia (C) dike swarms are within the Chief Joseph dike swarm. The Monument Dike Swarm (M) was the vent for the Picture Gorge Basalt. The Paso Basin is near the confluence of the Columbia and Snake Rivers. Map based on Hooper (1997).

    Almost everything about this volcanic province is impressive. The Columbia River Flood Basalt Province forms a plateau of 164,000 square kilometers between the Cascade Range and the Rocky Mountains. In all, more than 300 individual large (average volume 580 cubic km!) lava flows cover parts of the states of Idaho, Washington, and Oregon. At some locations, the lava is more than 3,500 m thick. The total volume of the volcanic province is 175,000 cubic km. Eruptions filled the Pasco Basin in the east and then sent flows westward into the Columbia River Gorge. About 85% of the province is made of the Grande Ronde Basalt with a volume of 149,000 cubic km (enough lava to bury all of the continental United States under 12 m of lava!) that erupted over a period of less than one million years. Flows eventually reached the Pacific Ocean, about 300 to 600 km from their fissure vents. The Pomona flow traveled from west-central Idaho to the Pacific (600 km), making it the longest known lava flow on Earth (the major- and trace-element compositions of the flow do not change over its entire length).


    Feeder dikes form the vents for the flood basalts and they trend to the north-northwest to south-southeast across eastern Oregon and western Idaho (Swanson and others, 1975). Hundreds of vents have been recognized and mapped. Small vents, such as spatter cones, are associated with the feeder dikes. The vents systems are 50 to more than 200 km long and a few kilometers wide. Some vents are hidden under younger flows. Photo of dike in the Chief Joseph dike swarm cutting across Grande Ronde Basalt. Photograph courtesy of Stephen Reidel.

    Most of the flows in the Columbia River Flood Basalt Province are tholeiitic basalt. Representative samples are given below. Data from Wright and others (in press) presented in Swanson and others (1989).

            1       2       3
    SiO2 53.84 50.94 52.00
    Al2O3 14.37 14.27 15.04
    FeO* 11.37 13.50 10.45
    MgO 5.25 4.57 7.19
    CaO 8.97 8.56 10.39
    Na2O 2.92 2.85 2.23
    K2O 1.10 1.25 0.65
    TiO2 1.75 3.12 1.62
    P2O5 0.23 0.68 0.24
    MnO 0.19 0.25 0.18
    FeO* = total FeO.
    1. High MgO Grande Ronde basalt.
    2. Roza Member of the Wanapum Basalt.
    3. Pomona Member of Saddle Mountains Basalt.

    Volcanism began about 17.5 million years ago and ceased about 6 million years ago.


    Most of the volume of the Columbia River Flood Basalt Province (85%) was erupted in only 1.5 million years from 17 to 15.5 million years ago. Volume of each formation, in cubic kilometers, is given in parentheses. Black dots separate formations. Data from Tolan and others (in press) presented in Swanson and others (1989).


    Comparison of the Roza Member (~ 14.5 million years ago, volume=1300 km3, emplacement=5-15 years, eruption rate=2600-8100 m2/s) of the Columbia River Flood Basalt Province to lava flows from 1. Kupaianaha (1986-1992, ~0.5km3, 5.6 years, 2-5m2/s), 2. Mauna Loa (1859, 0.27m3, 10 months, 4 m3/s), and 3. Laki (1783-1784, 14.7 km3, 8 months, 1150-4250 m3/s). From Self and others (1997).

    The tectonic origin of the flood basalts is not simple. Hooper (1997) identified three major factors:
    1. the Yellowstone hot spot;
    2. thinning of the continental lithosphere as a result of spreading behind the Cascade arc; and
    3. the proximity of the fissure vents to the tectonic boundary between accreted terranes made of thinner, denser oceanic lithosphere and the more competent lithospheres of the old North American Plate.

    Many flood basalt provinces are associated with known hot spots and the Yellowstone hot spot may have influenced magma generation for the Columbia River flood basalt but the vents were 300-400 km north of the hot spot track and the chemistry of the basalts suggest a source in the lithospheric mantle not the asthenosphere as expected for hot spot magmas.

    The area and volume of the Columbia River Flood Basalt Province are impressive but the volume is one-tenth the volume of other large igneous provinces such as Deccan, Parana, Karoo, and the Siberian Traps.

    ....................................................
    Large Igneous Provinces
    http://en.wikipedia.org/wiki/Large_Igneous Province

    Large igneous province

    From Wikipedia, the free encyclopedia

    A large igneous province (LIP) is an extensive region of basalts resulting from flood basalt volcanism.

    Contents

    [hide]

    Impact

    When created, these regions often occupy a few million km2 and have volumes on the order of 1 million km3. In most cases, the majority of a LIP's volume is emplaced in less than 1 million years. Some LIP's lie on continental crust, while others lie beneath the oceans in so-called oceanic plateaus.

    Theories of formation

    Many scientists argue that LIPs form as the result of mantle plumes that have only just arrived at the surface of the Earth. When a plume first arrives, they argue, the excess heat and chemical differences lead to an extended period of volcanism. Only subsequently does the plume cool and produce the kind of narrow channel of volcanism associated with features like the Hawaiian Islands.

    However, other scientists argue that large igneous provinces result from rifting and, in particular, the pulling apart of newly formed continental rifts without the need for deep seated plumes. It is possible that both theories may lead to LIP formation.

    Relationship to extinction events

    Because a LIP may in several cases have occurred simultaneously with oceanic anoxic events and extinction events, it has been proposed that the volcanic byproducts of LIP formation may have had a profound and deleterious effect on the global environment.

    Examples of LIPs

    These are well documented Provinces in geological research

    See also

    External links



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    Deccan Traps - Flood Basalts

    http://seattletimes.nwsource.com/html/nationworld/2002156517_global21.html

    Friday, January 21, 2005 - Page updated at 12:18 A.M.

    Volcanic activity eyed in "Great Dying" 250 million years ago

    The Washington Post


    WASHINGTON — Scientists call it "The Great Dying," a 250 million-year-old catastrophe that wiped out 90 percent of ocean species and 70 percent of land species in the biggest mass extinction in Earth's geologic history.

    The cause of the cataclysm is a matter of great dispute among paleontologists, but research released yesterday offers new evidence that global warming caused by massive and prolonged volcanic activity may have been the chief culprit.

    Huge amounts of carbon dioxide were released into the air from open volcanic fissures known to geologists as the "Siberian Traps," researchers said, triggering a greenhouse effect that warmed the Earth and depleted oxygen from the atmosphere, causing environmental deterioration and, finally, collapse.

    A second set of findings suggested that the warming also crippled the oceans' ability to refresh their oxygen supply, causing the seas to go sterile, destroying marine life and allowing anaerobic bacteria (which do not require oxygen) to release poisonous hydrogen sulfide into the air.

    The two reports, prepared independently, cast doubt on another theory: that "The Great Dying" was caused by the impact of an asteroid or comet like the one that triggered the extinction of the dinosaurs 65 million years ago. Both studies were published yesterday by Science Express, the online version of the journal Science.

    "This is not a world that is happy and then goes 'bang!' " said University of Washington paleontologist Peter Ward, leader of one of the studies. "This is a world that's in trouble for a long time, and then it gets in even worse trouble."

    Ward led a team of scientists in a seven-year project to chronicle 126 fossil skulls in a 1,000-foot-thick deposit of sedimentary rock in southeastern South Africa's Karoo Basin.

    Ward said the team's excavations showed a steady decline in the number of species over about 10 million years, followed by a sudden plunge 250 million years ago at the boundary between the Permian and Triassic periods of geologic time. The interval corresponds to a period of prolonged volcanic activity over one-third of modern-day Siberia.

    Temperatures climbed globally as carbon dioxide poured into the atmosphere and oxygen levels fell, forcing gasping animals to gather at sea level, he said. "And the plants are not dealing well with the heat" either, he added. "Eventually, the imbalance reaches a critical point and everything dies."


    The warming also meant that polar oceans were not cooled as much as they are today, and the cycle that circulates cold, oxygen- and nutrient-rich water between the poles and the tropics was slowed and even stopped, according to the second paper by a team of researchers led by Kliti Grice of the Curtin University of Technology in Perth, Australia.

    "This has devastating effects on the marine organisms that rely on oxygen and nutrients to survive," the team said in an e-mail. "In the worst-case ... a major part of the water column above the sea floor is devoid of oxygen."

    Analyzing sulfur and carbon isotopes from core samples taken from the ocean bed off the coast of northwestern Australia, the team detected molecular traces from green sulfur bacteria at the time of "The Great Dying."

    "The beauty of these [bacteria] is that they require sunlight and an anoxic [oxygen-free] environment," said team member Steven Turgeon, an Oak Ridge National Laboratory geochemist.

    This combination of factors indicates that large swatches of ocean below a depth of 300 feet — the deepest that significant light can penetrate — became sterile and that the entire ocean may have been oxygen-free.

    The Grice team did not address the cause of the lethal warming, but Ward said his team found no evidence of the residue that would have fallen after a comet or asteroid impact threw tons of dust into the air to trigger a sudden and catastrophic greenhouse effect.

    Still, University of Rochester scientist Robert Poreda, a proponent of the impact theory, noted that the "absence of evidence" at Karoo Basin "does not constitute evidence of absence."

    "We propose there was pre-existing volcanism" that became much worse because of the seismic energy released by the asteroid or comet impact, he said.

    >>>>>>>>>>>>>



    Layers of lava flows in Deccan TrapsAncient lava flows - Deccan Traps - lava meets Arabian Sea at Goa, India
    Ancient lava flows - Deccan Traps - meets Arabian Sea at Goa, India

    Deccan Traps - Lonar Crater - India

    Meteor crater( recent-in geological time) in Deccan Traps lava flow



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    Siberian Traps - Flood Basalts

    Layers of lava flows in Siberian TrapsRhyolithic flood eruption - ancient
    Flood Basalt...............






    save - flood basalts

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    Other Lesser, Catastrophic Explosive Eruptions

    Supervolcano

    From Wikipedia, the free encyclopedia

    http://en.wikipedia.org/wiki/Super_volcano
    (Redirected from Super volcano)
    Jump to: navigation, search
    For the docudrama, see Supervolcano (docudrama)

    A supervolcano refers to a volcano that produces the largest and most voluminous kinds of eruption on Earth. The actual explosivity of these eruptions varies, but the sheer volume of extruded magma is enough to radically alter the landscape and severely impact global climate for years, with a cataclysmic effect on life (see also nuclear winter).

    Contents

    [hide]

    Word origin

    The term was originally coined by the producers of the BBC popular science program, Horizon, in 2000 to refer to these types of eruption. That investigation brought the subject more into the public eye, leading to further studies of the possible effects.

    Large igneous provinces

    A large igneous province (LIP) is an extensive region of basalts on a continental scale, resulting from flood basalt eruptions. When created, these regions often occupy several million km² and have volumes on the order of 1 million km³. In most cases, the majority of this is laid down over an extended but geologically sudden period of less than 1 million years.

    Massive eruptions

    Eruptions with a Volcanic Explosivity Index of 8 (VEI-8) are mega-colossal events that extrude at least 1000 km³ of magma and pyroclastic material.

    Such an eruption would erase virtually all life within a radius of hundreds of kilometers from the site, and entire continental regions further out can be buried meters deep in ash.

    VEI-8 eruptions are so powerful that they form circular calderas rather than mountains because the downward collapse of land at the eruption site fills emptied space in the magma chamber beneath. The caldera can remain for millions of years after all volcanic activity at the site has ceased.

    Known eruptions

    Satellite image of Lake Toba.
    Satellite image of Lake Toba.

    VEI-8 volcanic events have included eruptions at the following locations. Estimates of the volume of erupted material are given in parentheses.

    The Lake Toba eruption plunged the Earth into a volcanic winter, eradicating an estimated 60%[1] [2] [3] [4] [5]of the human population, and was responsible for the formation of sulfuric acid in the atmosphere and the Millennial Ice Age.

    Many other supermassive eruptions have also occurred in the geological past. Those listed below measured 7 on the VEI scale. Most of these were larger than Tambora's eruption in 1815, which was the largest eruption in recorded history.

    For large flood basalt eruptions, see large igneous province.

    Media portrayal

    A two-part television docudrama entitled Supervolcano was shown on BBC, the Discovery Channel, and other television networks worldwide. It looked at the events that could take place if the Yellowstone supervolcano erupted. It featured footage of volcano eruptions from around the world and computer-generated imagery depicting the event. According to the program, such an eruption would have devastating effect across the globe and would cover virtually all of the United States with at least 1 cm of volcanic ash, causing mass destruction in the nearby vicinity and killing plants and wildlife across the continent. The dramatic elements in the program were followed by Supervolcano: The Truth About Yellowstone, a documentary about the evidence behind the movie. The program had originally been scheduled to be aired in early 2005, but it was felt that this would be insensitive so soon after the 2004 Indian Ocean earthquake. The program and its accompanying documentaries were released on DVD region 2 simultaneously with its broadcast.

    A National Geographic documentary called Earth Shocks portrayed the destructive impact of the rapid eruption of Lake Toba some 75,000 years ago and caused a phenomenon known as the Millennial Ice Age that lasted for 1000 years and wiped out more than 60%[7] [8] [9] [10] [11] of the global population of the time. An eruption of the Yellowstone supervolcano was originally one of the scenarios depicted in the docu-drama End Day, but was excluded from all airings to date for unknown reasons and is only presently mentioned at the show's BBC website.

    See also

    Volcanic winter

    From Wikipedia, the free encyclopedia

    http://en.wikipedia.org/wiki/Volcanic_winter

    Jump to: navigation, search

    A volcanic winter is the reduction in temperature caused by volcanic ash and droplets of sulfuric acid obscuring the sun, usually after a volcanic eruption.

    Contents

    [hide]

    Effects on life

    The causes of the bottleneck phenomenon, i.e., a sharp decrease in a species' population immediately followed by a period of great genetic divergence (differentiation) among survivors—might be attributed to volcanic winters. According to anthropologist Stanley Ambrose, such events diminish the population size to "levels low enough for evolutionary changes, which occur much faster in small populations, to produce rapid population differentiation".

    Ancient case of volcanic winters

    A terrific case of volcanic winter happened around 71,000–73,000 years ago following the supereruption of Lake Toba on Sumatra island (Indonesia). In the following 6 years there was the highest amount of volcanic sulphur deposited in the last 110,000 years, possibly causing complete deforestation in Southeast Asia and the cooling of sea temperatures by 3–3.5°C. Remarkably, the eruption almost caused an instant Ice Age on Earth by accelerating the glacial shift that already was going on, therefore causing massive population reduction among animals and human beings on Earth.

    This, combined with the fact that most human differentiations abruptly occurred at that same period, is a probable case of bottleneck linked to volcanic winters (see Toba catastrophe theory). On average, such super-eruptions and subsequent volcanic winters occur on our planet every 50,000 years.

    Recent cases of volcanic winter

    Pinatubo early eruption 1991
    Pinatubo early eruption 1991

    The scales of recent winters are more modest but their effects can be significant. A paper written by Benjamin Franklin in 1783 blamed the unusually cool summer of 1783 on volcanic dust coming from Iceland, where the eruption of Laki volcano had released enormous amounts of sulfur dioxide, resulting in the death of much of the island's livestock and a catastrophic famine which killed a quarter of the population. Temperatures in the northern hemisphere dropped by about 1°C in the year following the Laki eruption.

    The 1815 eruption of Mount Tambora, a stratovolcano in Indonesia, occasioned mid-summer frosts in New York State and June snowfalls in New England in what came to be known as the "Year Without a Summer" of 1816.

    In 1883, the explosion of Krakatoa (Krakatau) also created volcanic winter-like conditions. The next four years after the explosion were unusually cold, and the winter of 1888 was the first time snow fell in the area. Record snowfalls were recorded worldwide.

    Most recently, the 1991 explosion of Mount Pinatubo, another stratovolcano, in the Philippines cooled global temperatures for about 2-3 years, interrupting the trend of global warming which had been evident since about 1970.

    Further Reading

    See also

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