Implications of the melting depth and temperature of the Atlantic mid-ocean ridge basalts
Implications of the melting depth and temperature of the Atlantic mid-ocean ridge basalts
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大西洋洋中脊玄武岩融化深度和温度的影响
DOI：
10.1007/s13131-019-1363-0
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发表时间：
2019-11
影响因子：
1.4
通讯作者：
Zhou Haoda
中科院分区：
文献类型：
--
作者：
Guan Yili;Shi Xuefa;Yan Quanshu;Wei Xun;Zhang Yan;Xia Xiaoping;Zhou Haoda
洋中脊玄武岩（MORB）的微量元素组成和同位素比值变化大，很难用橄榄岩地幔部分熔融和分离结晶等岩浆作用解释。MORB的地球化学多样性归因于下伏地幔的大尺度不均匀性，这种不均匀性可能是由再循环地壳成分、陆下岩石圈、交代岩石圈和外核贡献的增加所引起的。在这项研究中，我们调查了沿着大西洋中脊（MAR）的MORB估计的温度和压力的部分熔融，并全面比较微量元素和同位素比值。来自地幔柱附近地区的MORB数据显示出很大的变化。地幔柱可以影响到1400km以外的洋中脊，但地幔柱效应并没有覆盖所有洋中脊段，没有地幔柱效应的洋中脊段没有出现温度、微量元素和同位素比值的异常。我们将上述现象归因于羽流的形状，我们将其归类为“管道状通道”和“煎饼状通道”。“饼状通道”热柱对地幔的影响是非定向的，但“管状通道”热柱对地幔的影响范围是选择性的。MORB的元素比表明，沿着MAR的MORB的地幔来源具有高度的非均匀性。我们认为，MORB源区的不均一性主要是由于源区存在俯冲板片和拆离下地壳。此外，从核幔边界携带物质的羽流可能会影响某些部分。
Mid-ocean ridge basalts (MORBs) are characterized by large variations in trace element compositions and isotopic ratios, which are difficult to be interpreted solely by using magmatic process such as partial melting of a peridotitic mantle and subsequently fractional crystallization. Geochemical diversity of MORBs have been attributed to large-scale heterogeneity within the underlying mantle, and the heterogeneity might have been caused by addition of recycled crustal component, subcontinental lithosphere, metasomatized lithosphere and outer core contribution. In this study, we investigated the MORBs along the Mid-Atlantic Ridge (MAR) by estimating the temperature and pressure of partial melting, and comprehensively comparing trace element and isotope ratios. The data for MORBs from areas close to mantle plumes show large variations. Mantle plumes can affect mid-oceanic ridges 1 400 km away, but plume effects did not cover all of the ridge segments, and those segments without plume effects did not have any abnormalities in temperature, trace element or isotope ratios. We ascribed the above phenomena to result from the shapes of the plume flow, which we categorized as “pipelike channels” and “pancake-like channels”. The “pancake-like channels” plumes affected the ambient mantle nondirectionally, but the range of the mantle affected by the “pipe-like channels” plumes were selective. Element ratios of MORBs reveal that the mantle source of the MORBs along the MAR is highly heterogeneous. We suggest that most of source heterogeneities of the MORBs may be due to the presence of subducted slab and delaminated lower crust in the source. In addition, the plume that carried materials from the core-mantle boundary may affect some of the segments.
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影响因子：
64.8
作者：
J. Brenan;H. Shaw;F. Ryerson
通讯作者：
J. Brenan;H. Shaw;F. Ryerson
影响因子：
12.1
作者：
M. Lustrino
通讯作者：
M. Lustrino
影响因子：
5
作者：
A. Stracke;B. Bourdon
通讯作者：
A. Stracke;B. Bourdon
影响因子：
5.3
作者：
C. Kincaid;J. Schilling;C. Gable
通讯作者：
C. Kincaid;J. Schilling;C. Gable
影响因子：
64.8
作者：
J. Schilling
通讯作者：
J. Schilling