Systematics of metals, metalloids, and volatiles in MORB melts: effects of partial melting, crystal fractionation and degassing (a case study of Macquarie Island glasses)
Systematics of metals, metalloids, and volatiles in MORB melts: effects of partial melting, crystal fractionation and degassing (a case study of Macquarie Island glasses)
复制标题
DOI：
10.1016/j.chemgeo.2011.04.008
复制
发表时间：
2012-04
期刊：
影响因子：
3.9
通讯作者：
Vadim Kamenetsky;S. Eggins
中科院分区：
文献类型：
--
作者：
Vadim Kamenetsky;S. Eggins
从中新世麦夸里岛蛇绿岩（西南太平洋）的镁玄武岩玻璃被用来了解地幔橄榄岩的渐进部分熔融的影响，以及随后的岩浆结晶和脱气洋中脊玄武岩的组成。这些玻璃由两套代表，近原始（第一组）和分馏（第二组），这表明明确的父母女儿的关系。他们的特殊成分的多样性，主要的，微量亲石和挥发性元素是共享的一组金属元素和类金属，在这项研究中分析激光烧蚀ICPMS。I族玻璃在通过晶体分馏（例如，V、Sc、Co、Ni、Cr、Zn）或熔体脱气（Cu）。在麦格理岛原始和分馏熔体中的元素的恒定或几乎恒定的比率用于识别类似的批量分配系数在熔化和晶体分馏，分别。估计的相对程度的不相容性在地幔熔融提供了限制的亲铁，亲铜和挥发性元素丰度的模型“原始”和“亏损”的地幔源。在所研究的玻璃中观察到的化学系统学可以进一步用于探索地幔源成分，包括参与岩浆生成的矿物相，以及控制地幔源和地幔源熔体中化学元素分馏的过程。
Magnesian basaltic glasses from the Miocene Macquarie Island ophiolite (SW Pacific) are used for understanding the effects of progressive partial melting of the mantle peridotite, and subsequent magma crystallisation and degassing on the composition of mid-ocean ridge basalts. These glasses are represented by two suites, near-primitive (Group I) and fractionated (Group II), which show clear parent–daughter relationships. Their exceptional compositional diversity in major, trace lithophile and volatile elements is shared by a set of metallic elements and metalloids, analysed in this study by laser ablation ICPMS. The Group-I glasses provide concentrations of compatible metals before they are severely modified by crystal fractionation (e.g., V, Sc, Co, Ni, Cr, Zn) or melt degassing (Cu). The constant or nearly constant ratios of the elements in the Macquarie Island primitive and fractionated melts are used for identification of similar bulk distribution coefficients during melting and crystal fractionation, respectively. The estimated relative degree of incompatibility during mantle melting provides constraints on the siderophile, chalcophile and volatile element abundances in the model “primitive” and “depleted” mantle sources. The chemical systematics observed in the studied glasses can be further used to explore mantle source compositions, including mineral phases involved in magma generation, and processes controlling fractionation of chemical elements in both mantle source and mantle-derived melts.