为什么会有一行沿着北美洲西北海岸的火山?- 江南体育网页版- - - - -地球科学堆江南电子竞技平台栈交换 最近30从www.hoelymoley.com 2023 - 07 - 06 - t19:10:29z //www.hoelymoley.com/feeds/question/144 https://creativecommons.org/licenses/by-sa/4.0/rdf //www.hoelymoley.com/q/144 17 为什么会有一行沿着北美洲西北海岸的火山? 克里斯•穆勒 //www.hoelymoley.com/users/53 2014 - 04 - 16 - t15:11:02z 2016 - 12 - 14 - t16:21:27z < p >在俄勒冈州胡德山是休眠火山,圣海伦火山在华盛顿和太Ranier都是活火山。是什么导致这一火山平行北美洲西北海岸海岸线的? < / p > //www.hoelymoley.com/questions/144/-/152 # 152 4 由amorfis回答为什么会有一行沿着北美洲西北海岸的火山? amorfis //www.hoelymoley.com/users/109 2014 - 04 - 16 - t16:06:05z 2014 - 04 - 16 - t16:06:05z < p >因为在这两个板块相遇的地方。大多数火山是在这样的地方——那里是板块之间的边界。< / p > //www.hoelymoley.com/questions/144/-/156 # 156 22 由乔院长回答为什么会有一行沿着北美洲西北海岸的火山? 乔院长 //www.hoelymoley.com/users/12 2014 - 04 - 16 - t16:15:24z 2016 - 12 - 14 - t16:21:27z < p >瀑布(太圣海伦火山的火山范围和太Ranier的一部分)是“火山弧”。“火山弧”等等)。< / p >

Volcanic arcs form at a regular distance (and fairly regular spacing) behind subduction zones. Subduction zones are areas where dense oceanic crust dives beneath more buoyant crust (either younger oceanic crust or continental crust).

The down-going oceanic plate begins to generate fluids due to metamorphic reactions that occur at a particular pressure and temperature. These fluids cause partial melting of the mantle above the down-going slab. (Contrary to what's often taught, the oceanic crust itself doesn't melt at this point - it's the mantle above it that does.)

This causes arc volcanoes to form at the surface at approximately where the down-going oceanic slab reaches ~100km depth (I may be mis-remembering the exact number).

However, there's an interesting story with the Cascades, the San Andreas Fault, and the Sierra Nevada.

Basically, Sierras are the old volcanic arc before an oceanic spreading ridge tried to subduct off the coast of California. (Search for the Farallon plate.) The ridge was too buoyant to subduct, so subduction stopped, shutting off the supply of magma to the volcanic arc. Because the motion of the Pacific Plate (on the other side of the spreading ridge that tried to subduct) was roughly parallel to the margin of North America, a strike slip boundary formed instead: The San Andreas Fault. Northward, there's still a remnant of the Farallon plate that's subducting beneath Northern CA, OR, WA, and BC. Therefore, the Cascades are still active arc volcanoes, while the Sierras are just the "roots" of the old arc.

//www.hoelymoley.com/questions/144/-/165 # 165 10 Neo的回答为什么会有一行沿着北美洲西北海岸的火山? Neo //www.hoelymoley.com/users/32 2014 - 04 - 16 - t17:01:49z 2014 - 04 - 16 - t17:01:49z < p >除了乔院长优秀的答案;还有一个更复杂的过程在太平洋西北地区。所述< a href = " http://www.nature.com/nature/journal/v482/n7385/full/nature10749.html?wt.ec_id=nature - 20120216 " > < / >,哥伦比亚河玄武岩的起源是由俯冲法拉龙板的破裂。激烈的地幔流削弱了板,最后脱离“主要”板块。解耦的地幔岩石圈留给“下沉”没有表面边界条件的约束(运动)推动热地幔在太平洋西北地区。这个热地幔的推动提供了极其丰富的可熔的地幔来源,导致火山活动增加。< / p >
Baidu
map