Extreme Mantle Source Heterogeneities Beneath the Northern East Pacific Rise — Trace Element Evidence From Near-Ridge Seamounts
Extreme Mantle Source Heterogeneities Beneath the Northern East Pacific Rise — Trace Element Evidence From Near-Ridge Seamounts
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DOI：
10.1201/9780429070877-9
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Y. Niu;R. Batiza
中科院分区：
文献类型：
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作者：
Y. Niu;R. Batiza
在这篇论文中，作者总结了他们对北纬 5 度到北纬 15 度之间东太平洋海隆 (EP R) 侧翼 50 个近山脊煤层熔岩的微量元素研究结果。这些海山熔岩以贫化的 N 型洋中脊玄武岩 (MORB) 为主，其中也有不同程度富集的 E 型 MORB 和一些与洋岛玄武岩 (OIB) 平均成分类似的极度富集岩浆。这种巨大的成分变化非常准确地反映了在 EPR 轴喷发的熔岩中所表现出的地幔来源的异质性。就不相容的微量元素丰度而言，这种源异质性很容易被设想为由于存在大小可变且分布不均匀的周围贫化地幔内的富集域。熔化这种异质源的地球化学后果是在熔岩中产生明显的混合关系。富集区域可能是由低度熔体非对称作用形成的岩脉或矿脉。正如地幔断层摄影研究所表明的，低度融化可能与夏威夷羽流物质向东流向 EPR 的地流层流动有关。微量元素数据表明，浓缩物质（夏威夷羽状物质）最终源自回收的洋壳。
In t his paper the authors sum marize t he result s of their t race element st udy of lavas from 50 near-ridge seam ount s on the flanks of the East P acific Rise (EP R) bet ween 5ûN and 15ûN. T hese seamount lavas are dom inated by deplet ed N-type m id-ocean ridge basalts (MORB) with variably enriched E-t ype MORB and some ext rem ely enriched ones resembling average com positions of ocean island basalts (OIB). T his large composit ional variation reflects wit h great fidelit y the m ant le source het erogeneity that is m asked in lavas erupt ed at t he EP R axis. In term s of incom patible trace elem ent abundances, th is source heterogeneity can be readily envisioned as being due t o t he presence of enriched domains of variable size and unevenly distribut ed within t he ambient depleted m antle. T he geochemical consequence of m elt ing such a heterogeneous source is to produce apparent mixing relat ionships in t he lavas. T he enriched domains may be dikes or veins resulting from low-degree m elt m et asom atism . T he low degree m elts may be genetically relat ed t o eastward ast henospheric flow of Hawaii p lume m at erials towards t he EPR, as suggested by mant le t om ographic st udies. T race element dat a suggest t hat t he enriched m at erials (hence Hawaii p lume m at erials) are ult imately derived from recycled oceanic crust .