User:Chris.urs-o/Sandbox.004

Overview proposal

The North American craton heads Southwest, heading around az= 240°±4° (Raton hotspot).

East of the edge of the North American craton, Basin and Range Province.

• Yellowstone hotspot, around 17 Ma, apparent heading 28° (Northeast).
• These lineaments could be an indication of it as well:
  • Crater Flat-Reveille Range-Lunar Crater Lineament.
  • Colorado Mineral Belt.
  • Idaho City, Trans-Challis fault zone, Custer graben, Challis volcanic field, Gibbonsville.
  • The Jemez volcanic lineament (Raton hotspot): San Carlos volcanic field, Springerville volcanic field, Red Hill volcanic field, Zuni-Bandera volcanic field, Mount Taylor volcanic field, Jemez volcanic field and maybe (Ocate volcanic field, Raton-Clayton volcanic field, and Mesa de Maya).
  • (Smith, R.L. and Luedke, R.G., 1984, Potentially active volcanic lineaments and loci in western conterminous United States, in: Explosive Volcanism: Inception, Evolution, and Hazard, National Research Council, Geophysics Study Committee, 47-66.)

East of Snake River, Oregon-Idaho graben, Steens Mountain fault scarp, Northwest Nevada volcanic field (NWNV), Walker Lane and trough, Owens Valley and graben, Death valley, Imperial rift valley, and Gulf of California.

• The current view of geologists is that the Walker Lane takes up 15 to 25 percent of the boundary motion between the Pacific Plate and the North American Plate, the other 75 percent being taken up by the San Andreas Fault system to the west.
• (Stateline fault system: A new component of the Miocene-Quaternary Eastern California shear zone Bernard Guest et al., Division of Geological and Planetary Sciences, California Institute of Technology (2007))
• (Active Faulting in the Walker Lane)
• It could be an indication of the pulling force of the Earth Upper mantle convection, e.g. the extension in the Basin and Range Province:
  • High Lava Plains trend: Newberry Volcano, Duck Butte at 10.5 Ma in the East. The spacing of the isochrons indicates propagation rates of 35 km/m.y. from 10 to 5 Ma and 15 km/m.y. since 5 Ma, heading around 281°.
  • (High Lava Plains trend, Brennan T. Jordan, Earth Sciences Program, University of South Dakota).
  • Rio Grande rift, Nevada Rift zone, Oregon-Idaho graben, Great Rift of Idaho.
• The different motion East and West of the Oregon-Idaho graben could be the reason of the NW-SE fault zones: Brothers, Eugene-Denio, Modoc, Olympic-Wallowa Lineament, Oregon.

East of the San Andreas Fault

• The rate of slippage averages approximately 33–37 mm/year across California.
• (Wallace, Robert E. "Present-Day Crustal Movements and the Mechanics of Cyclic Deformation". The San Andreas Fault System, California. Retrieved 2007-10-26.)

San Juan volcanic field

San Juan volcanic field
Highest point
Coordinates	37°53′36″N 106°46′28″W
Geography
Location	Colorado, USA
Geology
Mountain type	Volcanic field

San Juan volcanic field is a volcanic field in New Mexico, USA.

Notable calderas

Cochetopa

La Garita North

Lake City

Platoro

Nelson Mountain

Bachelor

Creede

La Garita South

class=notpageimage|

Colorado volcanism. Links: La Garita, Cochetopa and North Pass (North Pass), Lake City, and Dotsero.

Name	Elevation	Coordinates	Age
Cochetopa Caldera	-	38°12′N 106°45′W
La Garita North Caldera	-	37°57′N 106°48′W
Nelson Mountain Caldera	-	37°58′N 106°56′W
Bachelor Caldera	-	37°49′03″N 106°54′46″W
Creede Caldera	-	37°45′34″N 106°56′20″W
La Garita South Caldera	-	37°34′N 107°00′W
Lake City Caldera	-	38°01′31″N 107°23′04″W
Platoro Caldera	-	37°21′08″N 106°31′52″W

See also

• List of volcanoes in the United States of America

Draft

The Mogollon caldera (34 Ma) is preserved only as a fragment in the wall of the Bursum caldera. The Emory caldera (34 Ma) is about 50 km east of the Mogollon Mountains, and only the high-silica facies of its presumed outflow sheet (Fall Canyon Tuff) reaches the Mogollons. The Gila Cliff Dwellings caldera (30 Ma), earlier interpreted as the source of the Bloodgood Canyon Tuff, probably is a large remnant of a caldera or pair of calderas that were the source of the Davis Canyon and Shelley Peak Tuffs. The Bloodgood Canyon Tuff was most likely erupted from the Bursum caldera (29–28 Ma), but ponded in the Gila Cliff Dwellings caldera. Lipman, P. W. (1984), The Roots of Ash Flow Calderas in Western North America: Windows Into the Tops of Granitic Batholiths, J. Geophys. Res., 89(B10), 8801–8841. San Juan, Mogollon-Datil, Marysvale, Latir-Questa, Chiricahua-Turkey Creek, Challis, and Boulder Batholith-Elkhorn Mountains http://www.cliffshade.com/colorado/geo_overview.htm NEW MEXICO BUREAU OF GEOLOGY & MINERAL RESOURCES, BULLETIN 160, 2004 Geochronology of the central Colorado volcanic field William C. McIntosh and Charles E. Chapin http://geoinfo.nmt.edu/publications/bulletins/160/downloads/10mcntsh.pdf The ~38-33 Ma Bonanza volcanic center is located north of the Rio Grande Rift and along a NNW alignment with the Mt. Aetna and Grizzly Peak calderas to the north.

San Juan volcanic field

The central Colorado volcanic field (CCVF) consists of at least ten late Eocene/Oligocene (38–29 Ma) eruptive centers and their volcanic products dispersed over approximately 22,000 km2 in the Southern Rocky Mountains. The CCVF originally covered most of the Sawatch Range, southern Front Range, Wet Mountains, northern Sangre de Cristo Range, and the areas between. Outflow aprons extended onto the High Plains to the east, merged with the San Juan volcanic field to the southwest, and overlapped the Colorado Mineral Belt on the north and west. The CCVF was severely dissected by Neogene faulting and erosion leaving widely scattered remnants, the largest of which is the Thirtynine Mile volcanic area (previously known as the Thirtynine Mile volcanic field), located between South Park and the Arkansas River.

The Mogollon-Datil volcanic field is part of a discontinuous belt of middle Cenozoic volcanism that runs from the Sierra Madre Oriental in central Mexico, through the Trans-Pecos volcanic field in west Texas, and northward to the San Juan volcanic field in southwestern Colorado. Extension began in this region about 36 million years ago. The extensional faults trend north-south on the east side of the field, northeast on the northwest side of the field, and northwest on the southwest side of the field.

(Chapin, C.E., Wilks, M. and McIntosh, W.C., 2004, Space-time patterns of Late Cretaceous to present magmatism in New Mexico—comparison with Andean volcanism and potential for future volcanism:New Mexico Bureau of Geology and Mineral Resources Bulletin 160, p. 13-40.)

Mogollon-Datil volcanic field (South part, Bootheel volcanic field) and Jemez volcanic field, New Mexico, Trans-Pecos volcanic field, Texas, Sierra Blanca and Taos Plateau volcanic field, New Mexico, San Juan volcanic field and Cripple Creek volcanic field, Colorado.

Great Basin volcanic locus? Latir-Questa volcanic locus?

McKee, E. H. (1971). "Tertiary Igneous Chronology of the Great Basin of Western United States–Implications for Tectonic Models". Geological Society of America Bulletin. 82 (12): 3497–3502. doi:10.1130/0016-7606(1971)82[3497:TICOTG]2.0.CO;2. Retrieved 09-04-2010. {{cite journal}}: Check date values in: |accessdate= (help) U.S. Geological Survey, Menlo Park, California 94025

The chronology of igneous activity in the Great Basin of western United States is used as a time framework for a simple plate model. This chronology suggests that a plate (Farallon plate) became underthrust to sufficient depth by the middle Tertiary to trigger the eruption of volcanic rocks of andesitic to rhyolitic composition in the central part of the Great Basin, 40 m.y. ago. This plate continued to be underthrust until about 19 m.y. ago, at which time it was completely consumed and volcanic activity ceased. When the oceanic ridge reached a certain point under the Great Basin about 16 m.y. ago, this resulted in the widespread eruption of olivine basalt and the main initial phase of Basin and Range faulting.

Digital Geology of Idaho - Basin and Range Province - Tertiary Extension

Basin and Range extension began during the Miocene Epoch (~17 Ma) near the Northern Nevada Rift in the center of the province and has continued through present, propogating westward toward the Sierra Nevada and eastward into southeastern Idaho and westernmost Wyoming. Extension is a result of the cessation of the compression during the Cordilleran Orogeny. Prior to Basin and Range extension, the Pacific Plate was subducting underneath the North American Plate in a compressional regime. This period of subduction included about 200 million years worth of orthogonal compression. In Eocene time, plate interactions changed from orthogonal compression to oblique strike-slip (transform) along the San Andreas Fault system in California.

The map shows the entire Basin and Range Province, including accommodation zones, transfer zones and volcanism associated with extension.

Digital Geology of Idaho - Challis Volcanics

The Challis volcanic episode (Challis volcanic arc) was active during the Eocene, between ~52-39 Ma, with the bulk of the eruption between 51-45 Ma. Prior to Eocene time, before ~60 Ma, the convergence rate of the Farallon and North American Plates was very fast. The angle of subduction was shallow and the subducting slab of the Farallon Plate reached as far as eastern Wyoming underneath the North American Plate (Figure 3). This far-reaching subducting slab set the stage for widespread volcanism along the northwestern side of the United States and southwestern British Columbia.

Around 56 Ma, the subduction rate slowed and the angle of subduction became much steeper.

Laramide orogeny

Most hypotheses propose that the angle of subduction became shallow, and as a consequence, no magmatism occurred in the central west of the continent, and the underlying oceanic lithosphere actually caused drag on the root of the overlying continental lithosphere. One cause for shallow subduction may have been an increased rate of plate convergence.

Hawaiian – Emperor seamount chain

A bend corresponding to rocks between 41 and 43 million years old sharply divides the Hawaiian and Emperor sections. The chain's length, orientation and distance between volcanoes records the direction and speed of the Pacific Plate's movement. Approximately 40–50 Ma, it is thought to have suddenly changed direction, because of the subduction of the spreading ridge separating the Pacific and Izanagi plates, and the initiation of subduction along much of the Pacific Plate's western boundary. Whittaker, J. M.; MüLler, R. D.; Leitchenkov, G.; Stagg, H.; Sdrolias, M.; Gaina, C.; Goncharov, A. (2007-10-05). "Major Australian-Antarctic Plate Reorganization at Hawaiian – Emperor Bend Time". Science. 318 (5847). American Association for the Advancement of Science: 83–86. doi:10.1126/science.1143769. ISSN 0036-8075. PMID 17916729.

Ash

[NASA - Volcanoes and Global Cooling]

Volcanic ash particles have a maximum residence time in the troposphere of a few weeks, and the finest tephra particles remain in the stratosphere for only a few months, and have only minor climatic effects. The major climate influence from volcanic eruptions is caused by gaseous sulfer compounds, chiefly SO2, which reacts with OH and H20 in the stratosphere to create H2SO4 which can remain in the stratosphere for several years.

One more minor quibble, since I can't edit the page directly. The abstract for the article I linked says that stratospheric S-aerosols have an e-folding residence time of 1 year, it is misleading to rewrite that for the wikipedia to page to drop the e-folding phrasing, but keep in the residence time of 1 year. E-folding time is the time it takes to drop to 1/e, ~1/2.7 of the initial value; for a major volcanic eruption, half of the original aerosols are still quite a lot and still exert an atmospheric effect, if you look at the cooling for major eruptions of the last centry it continues for 2-3 years. The text I suggested referenced a residence time beyond the 1 year efolding time of the abstract, to take into account the discussion of aerosol persistance in the body of the article, the known long term cooling effects, and to simplify the terminology for a reader who doesn't understand the efolding meaning. I'd suggest that my original phrasing be retained, or the e-folding phrasing of the abstract be retained.

• Robock, Alan (2000). "Volcanic eruptions and climate". Reviews of Geophysics. 38 (2): 191–219. doi:10.1029/1998RG000054.
• Robock, A.; Ammann, C.M.; Oman, L.; Shindell, D.; Levis, S.; Stenchikov, G. (2009). "Did the Toba Volcanic Eruption of ~74k BP Produce Widespread Glaciation?". Journal of Geophysical Research. 114: D10107. doi:10.1029/2008JD011652.

The second paragraph of atmospheric effects is completely wrong, according to the current best scientific knowledge, and does not reflect any of the understanding of volcanic dynamics learned since the early 80's. Volcanic ash only has a residence time in the stratosphere of a few months, and has been found not to be responsible for the long term climatic effects. Volatiles, specifically SO2 have a much longer residence time in the stratosphere, where they form aerosols/ice particles which are the source of the long term climatic effects, not fine ash particles which are glass and crystal fragments. Good references to use:

• "Volcanic Sulfur Aerosols Affect Climate and the Earth's Ozone Layer - Volcanic ash vs sulfur aerosols". U.S. Geological Survey. Retrieved 2010-04-21.
• Sigurdsson, H. (August 1982). "Volcanic pollution and climate -- the 1783 Laki eruption". American Geophysical Union, EOS Transactions. 10 (32): 601–602. doi:10.1029/EO063i032p00601.
• "Historic eruptions in Tambora (1815), Krakatau (1883), and Agung (1963), their stratospheric aerosols, and climatic impact". Quaternary Research. 18 (2): 127–143. September 1982. doi:10.1016/0033-5894(82)90065-5. {{cite journal}}: Cite uses deprecated parameter |authors= (help)
• Self, S. (1998), "The atmospheric impact of the 1991 Mount Pinatubo eruption", in Newhall, C.G., Punongbayan, R.S. (ed.), Fire and Mud, Eruptions and Lahars of Mount Pinatubo, Philippines, Washington: Smithsonian Institution - Global Volcanism Program, p. 1126, retrieved 2010-04-21 {{citation}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: multiple names: editors list (link)
• McGee, Kenneth A. (1997). Impacts of volcanic gases on climate, the environment, and people, Report 97-262. U.S. Geological Survey Open-File. p. 2. Retrieved 2010-04-21. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

Vandalism and Wikipedia

Flagged revisions

Wikipedia is not only a sandbox for Meta-Wiki anymore. It is a successful club helping primary, secondary and college students. And so it is an internet platform that is checked out. So first the teenie makes a test, "Hello" and "I was here"... And gets a friendly warning. Afterwards, he gets bolder: "NNN is gay"... And gets a less friendly warning. Then he gets even bolder and messes the User page that is responsible for the warning, or he demonstrates how clever he is and changes one number destroying a data set. As he gets older he writes hate articles of BLPs, or he joins a club of warlords. These all are misdoings, he is misusing donations, voluntary work time and donation of computer time... We are a club that tries to avoid misleading students, tries to improve the community, and we do not support hate and war...

• Vandals are not new wikipedians
• "New edits" and its reverts and its undoes are not really, really new edits
• Since the Subprime mortgage crisis people are losing their internet connection

Chain of events

• Yellowstone Caldera (size: 45 x 85 km); 640 ka
  • Repose: 660 ka
• Henry's Fork Caldera (size: 16 km wide); 1.3 Ma
  • Repose: 800 ka
• Island Park Caldera (size: 100 x 50 km); 2.1 Ma
• Eyjafjallajökull, which has a crater 3–4 kilometres (1.9–2.5 mi) in diameter, erupted in 920, 1612 and again from 1821 to 1823. The eruptions were always followed by an eruption of Katla.
• The San Andreas fault has one big earthquake all 101 years by computer simulations. So, the probability of a big one 1906 San Francisco earthquake after 2007 gets higher...
• A Tectonic Plate can't change without changing the position of almost all tectonic plates on a surface of a globe. Since there is seismometers, the South East, South West, North West, North East of the Pacific Ring of Fire adjust themselves a little bit more after major rare earthquakes.