Mantle composition controls the development of an Oceanic Core Complex
Mantle composition controls the development of an Oceanic Core Complex
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地幔成分控制海洋核心复合体的发展
DOI：
10.1002/ggge.20046
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Wilson S
中科院分区：
文献类型：
--
作者：
Wilson S
洋壳的厚度和连续性是可变的。缓慢扩张的海脊段通常包含“岩浆”或构造延伸的区域，暴露下地壳和上地幔的区域，并且很少或没有最近的火山活动。这些地区散布着由“强大的”岩浆增生产生的“正常”火山地壳。构造扩张通过低角度伸展拆离断层上的位移来调节，形成大洋核杂岩。虽然“amagmatic”扩展似乎是常见的缓慢扩展速率，鲜为人知的机制，驱动从岩浆扩展的过渡。在这里，我们报告了对大西洋中脊（13°N-14°N）进行详细研究的结果，并显示，尽管存在几个核心复合体，但熔体生产仍然沿着现今的扩张轴相似，喷发均匀的“正常”洋中脊玄武岩。然而，在离轴的老地壳形成过程中的熔体产生来自于非均匀地幔的低程度熔融。在这一岩浆限制阶段，熔体生产是有限的来源组成。少量的富集玄武岩（M1）被生产出来，来自嵌入在成分耗尽的上地幔中的富集成分不均匀性的低分数熔体，这反过来又喷发出低分数不相容元素贫乏的玄武岩（M2）。由于岩浆流量低，地壳薄，不足以完全容纳海底扩张。薄地壳的断裂作用导致了拆离断层的发育和OCC的形成。因此，我们建议，低熔体生产的时期，直接导致亏损，非均匀地幔驱动从岩浆到amagmatic扩展的过渡。
The thickness and continuity of oceanic crust is variable. Slow‐spreading ridge segments often contain areas of ‘amagmatic’ or tectonic extension, exposing areas of lower‐crust and upper‐mantle, and having little or no recent volcanism. These are interspersed with areas of ‘normal’ volcanic crust generated by ‘robust’ magmatic accretion. Tectonic spreading is accommodated by displacement on low‐angle extensional detachment faults, forming Oceanic Core Complexes. Although ‘amagmatic’ extension appears to be common at slow spreading rates, little is known about the mechanisms that drive the transition from magmatic spreading. Here, we report results from a detailed study of the Mid‐Atlantic Ridge (13°N–14°N) and show, paradoxically, that despite the presence of several Core Complexes, melt production remains similar along the present‐day spreading axis, which erupts homogeneous ‘normal’ mid‐ocean ridge basalt. However, melt production during formation of the older crust off‐axis was derived from substantially lower degrees of melting of a heterogeneous mantle. During this magmatically restricted phase, melt production was limited by source composition. Small volumes of an enriched basalt (M1) were produced, derived from low‐fraction melts of enriched compositional heterogeneities embedded in an otherwise compositionally depleted upper‐mantle, which, in turn, erupted low‐fraction incompatible‐element‐poor basalts (M2). As a consequence of low magma flux, the crust was thin and insufficient to fully accommodate seafloor spreading. Faulting of this thin crust resulted in the development of detachment faults and the formation of OCCs. Thus, we propose that periods of low melt production, resulting directly from depleted, heterogeneous mantle drives the transition from magmatic to amagmatic spreading.
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影响因子：
5.3
作者：
MacLeod, C. J.;Searle, R. C.;Harris, M.
通讯作者：
Harris, M.
DOI：
10.2973/odp.proc.ir.209.2004
发表时间：
2004-09
期刊：
--
影响因子：
--
作者：
P. Kelemen;E. Kikawa;D. Miller
通讯作者：
P. Kelemen;E. Kikawa;D. Miller
影响因子：
3.9
作者：
R. Hannigan;A. Basu;F. Teichmann
通讯作者：
R. Hannigan;A. Basu;F. Teichmann
大西洋中脊下方尖晶石相和斜长石相过渡条件下橄榄岩-熔体相互作用：来自 13°N 橄榄岩的见解
DOI：
--
发表时间：
2009
期刊：
影响因子：
--
作者：
A. Pertsev;Nikolay S. Bortnikov;L. Aranovich;E. A. Vlasov;V. Beltenev;V. N. Ivanov;S. G. Simakin
通讯作者：
S. G. Simakin
从广角地震层析成像获得的南纬 5°大西洋中脊地壳厚度和结构的沿轴和跨轴变化：对脊分割的影响
DOI：
--
发表时间：
2009
期刊：
影响因子：
--
作者：
L. Planert;E. Flueh;T. Reston
通讯作者：
T. Reston