Scoring hotspots: The plume and plate paradigms
Scoring hotspots: The plume and plate paradigms
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评分热点：羽流和板范例
DOI：
10.1130/0-8137-2388-4.31
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发表时间：
2005
期刊：
影响因子：
2.9
通讯作者：
D. L. Anderson
中科院分区：
文献类型：
--
作者：
D. L. Anderson
中板和沿脊熔融异常的成因是有争议的。假设包括，在一种极端情况下，集中的热地幔从最深的地幔上涌，在另一种极端情况下，由应力、板块构造和肥力变化主导的浅层过程，以及在熔点附近的软流圈。提出了一个更新的热点列表，并根据深层热羽和浅层（板块和软流层）假设的相关标准进行了测试。Courtillot等人（2003）的独特投票方法被应用于羽流假说和其他关于融化异常的假说。尽管一些“主要”（即潜在的深部）热点（冰岛、夏威夷、伊斯特、路易斯维尔、阿法尔、重新统一和特里斯坦）使用所选择的主观羽流标准得分很高，但使用更适合于深部或热过程的标准（如岩浆温度、热流、过渡带厚度和高分辨率上、下地幔地震层析成像结果）得分很低。特别是冰岛、复活节、阿法尔、特里斯坦和黄石公园还没有被断层扫描证实。它们是浅层特征，具有明确的板块构造解释。对于大多数熔融异常（又名“热点”），羽流假说在与之竞争的假说（如应力和裂缝控制的岩浆作用，与板块构造有关的机制）中得分很低。根据结果，大多数“热点”，包括提出的“主要”或羽流候选热点，不太可能是由来自深部热边界层的热羽流引起的。在山脊上或山脊外的融化异常，似乎是包括再循环在内的非刚性板块构造的自然结果，不需要特别的解释，比如穿越整个地幔的狭窄热不稳定性。因此，板块构造、板块边界、全球板块重组、正岩浆活动、熔融异常、火山链和地幔地球化学可以统一为一个理论。
The origin of midplate and along-ridge melting anomalies is controversial. Hypotheses involve, at one extreme, concentrated hot mantle upwellings from the deepest mantle and, at the other extreme, shallow processes dominated by stress, plate tectonics, and fertility variations, along with an asthenosphere that is near the melting point. An updated hotspot list is presented and is tested against criteria relevant to both the deep thermal plume and the shallow (plate and asthenosphere) hypotheses. The unique polling approach of Courtillot et al. (2003) is applied to the plume hypothesis and to other hypotheses for melting anomalies. Although some “primary” (i.e., potentially deep-seated) hotspots (Iceland, Hawaii, Easter, Louisville, Afar, Re-union, and Tristan) score well using the chosen subjective plume criteria, they score poorly using criteria more appropriate to deep or thermal processes, such as magma temperature, heatflow, transition zone thickness, and high-resolution upper and lower mantle seismic tomographic results. In particular, Iceland, Easter, Afar, Tristan, and Yellowstone have not been confirmed by tomography. They are shallow features with well-defined plate tectonic explanations. For most melting anomalies (aka “hotspots”) the plume hypothesis scores poorly against competing hypotheses such as stress- and crack-controlled magmatism, mechanisms that are associated with plate tectonics. Based on the results, most “hotspots,” including proposed “primary” or plume-candidate hotspots, are unlikely to be caused by thermal plumes from deep thermal boundary layers. Melting anomalies, on- or off-ridge, appear to be a natural result of nonrigid plate tectonics, including recycling, and do not require an extraordinary explanation, such as narrow thermal instabilities that traverse the whole mantle. Thus plate tectonics, plate boundaries, global plate reorganization, normal magmatism, melting anomalies, volcanic chains, and mantle geochemistry can be unified into a single theory.