Yellowstone plume trigger for Basin and Range extension, and coeval emplacement of the Nevada-Columbia Basin magmatic belt
Yellowstone plume trigger for Basin and Range extension, and coeval emplacement of the Nevada-Columbia Basin magmatic belt
复制标题
DOI：
10.1130/ges01051.1
复制
发表时间：
2015-04-01
期刊：
影响因子：
2.5
通讯作者：
Morgan, Lisa A.
中科院分区：
文献类型：
--
作者：
Camp, Victor E.;Pierce, Kenneth L.;Morgan, Lisa A.
在17-16 Ma，广泛的伸展开始于横跨盆地和山脉省的北方和中部，与沿沿着内华达-哥伦比亚盆地岩浆带的岩浆活动同时发生，这是一个由岩墙和火山中心组成的线性区域，从内华达州南部延伸到华盛顿东部的哥伦比亚盆地，长度超过1000 km。这条带是在与黄石地幔柱的到来相关的拉长的岩石圈下熔融区上方产生的，由于通过胡安德富卡板中的传播断裂的地幔柱上升，形成了南北向的平板形状。沿岩浆带的岩脉走向沿着为245 ° ~ 250 °的伸展方向，但在同时代和较年轻的盆岭断裂作用中，这种走向与区域伸展方向280 ° ~ 300 °呈斜向，相差约45 °。现场关系表明，这种岩浆趋势并不受上地壳区域应力的控制，而是受到来自下方的岩浆超压和强岩脉注入的控制，其方向继承自岩石圈下地幔的更深过程。南半部的地幔上涌的拉长带是侵位在一个隆起的岩石圈与来自晚白垩世到第三纪中期地壳增厚的表面。这个高内华达高原在区域应力的影响下，部分来自太平洋-北美板块相互作用引起的边界力，具有高重力势能。地幔柱在17-16 Ma到达，导致岩石圈的平流热弱化、地幔牵引、拆沉，并增加了北方和中央盆地和山脉的浮力。它不是盆地和山脉扩张的唯一原因，而是已经处于区域崩溃边缘的内华达高原扩张的催化剂。
Widespread extension began across the northern and central Basin and Range Province at 17-16 Ma, contemporaneous with magmatism along the Nevada-Columbia Basin magmatic belt, a linear zone of dikes and volcanic centers that extends for >1000 km, from southern Nevada to the Columbia Basin of eastern Washington. This belt was generated above an elongated sublithospheric melt zone associated with arrival of the Yellowstone mantle plume, with a north-south tabular shape attributed to plume ascent through a propagating fracture in the Juan de Fuca slab. Dike orientation along the magmatic belt suggests an extension direction of 245 degrees-250 degrees, but this trend lies oblique to the regional extension direction of 280 degrees-300 degrees during coeval and younger Basin and Range faulting, an similar to 45 degrees difference. Field relationships suggest that this magmatic trend was not controlled by regional stress in the upper crust, but rather by magma overpressure from below and forceful dike injection with an orientation inherited from a deeper process in the sublithospheric mantle. The southern half of the elongated zone of mantle upwelling was emplaced beneath a cratonic lithosphere with an elevated surface derived from Late Cretaceous to mid-Tertiary crustal thickening. This high Nevadaplano was primed for collapse with high gravitational potential energy under the influence of regional stress, partly derived from boundary forces due to Pacific-North American plate interaction. Plume arrival at 17-16 Ma resulted in advective thermal weakening of the lithosphere, mantle traction, delamination, and added buoyancy to the northern and central Basin and Range. It was not the sole cause of Basin and Range extension, but rather the catalyst for extension of the Nevadaplano, which was already on the verge of regional collapse.