大西洋中段(14-16°N)交代橄榄岩:熔体性质及慢速扩张洋脊地幔改造意义
结题报告
批准号:
42003027
项目类别:
青年科学基金项目
资助金额:
24.0 万元
负责人:
周翔
学科分类:
岩石地球化学
结题年份:
2023
批准年份:
2020
项目状态:
已结题
项目参与者:
周翔
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中文摘要
熔体交代作用会导致局部地幔发生化学成分和物理性质的改变并调整地幔在空间上的不均匀分布。洋中脊是现代地球岩浆活动最频繁的区域,慢速扩张洋脊的岩浆以何种机制穿过岩石圈地幔上升至地表目前仍有争论,熔体迁移诱发的交代作用过程与地幔改造效应也需进一步研究。大西洋洋中脊北纬14-16°区域属慢速扩张环境,该区域20-40%的地幔岩有被熔体交代的痕迹。项目拟对Akademik Boris Petrov号和Researcher号科考船在该海域拖网采集的含长石方辉橄榄岩、富单斜辉石纯橄岩、含长石纯橄岩、富铬铁矿纯橄岩等交代橄榄岩,开展以岩相学观察为基础的矿物学、岩石学、地球化学综合研究。查明交代熔体性质,揭示岩浆经历熔岩反应后的成分演化趋势。精确还原交代反应过程,为探讨慢速扩张洋脊岩浆从源区上升穿过岩石圈的机制提供约束。通过剖析地幔顶部复杂岩性共生与区域成分异常的成因,推进对大洋岩石圈地幔精细结构的认识。
英文摘要
Mid-ocean ridge basalts are the most abundant magma on Earth. However, the mechanism that controls its migration from asthenospheric mantle to the seafloor is still not well constrained. There are two end-member, not necessarily contradictory models: “focused or channelized melt flow” and penetrative “reactive porous flow”. It is not clear which has the greater influence of the composition of the basalts. This problem is especially unclear at the slow-spreading ridges where there is a lithosphere 10-20 km beneath the volcanic zone. Identifying the extent to which the magmas interact with the mantle wall-rock during transport through the lithosphere, and the changes in mineralogy and composition of mantle and melt that result, will provide a necessary constraint. Locally the melt metasomatizes the residual mantle producing chemical changes and physical modification of the mantle rocks, thus reworking the composition and structure in upper mantle both beneath and away from the ridge axis. .The Mid-Atlantic Ridge is a slow-spreading rate at 20-30 millimeter per year. This project focus on a section from 14° to 16°N where mantle peridotites have been well sampled. In this area, ODP-Leg 209 drilled peridotites at Sites s1274 and 1275 with 20 to 40 vol.% melt-metasomatized peridotite. These rocks ‘impregnated peridotites’, include plagioclase-bearing harzburgite, plagioclase-bearing dunite, and clinopyroxene-rich dunite. These samples provide a unique opportunity to exam melt migration models, and decipher how melt metasomatism affects the shallow lithosphere. Therefore, this proposed project will investigate the petrogenesis of impregnated peridotites collected at 9 stations during RV Akademik Boris Petrov Cruise 16 (Russian), mantle peridotites cored by ODP Leg 209 in the same area, as well as a unique and diverse large mantle dredge haul (MM-81) from a NOAA Researcher Cruise (American). Based on careful petrography, we will carry out systematic petrologic, mineralogic and geochemical studies, especially using in-situ micro-analytical techniques (EPMA, EBSD and LA-ICPMS). This study will aim to determine the composition of the melts that reacted with the rocks and the conditions under which the different lithologies above were metasomatized, constraining the temperature, pressure, and melt/rock ratios involved in the reactions, and unravel the mineral textures and fabrics produced during the reaction process. This study will not only to unravel melt migration mechanisms beneath a long section of slow-spreading ridge, but also highlight the potential factors controlling the heterogeneity in abyssal peridotites.
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DOI:10.1016/j.lithos.2022.106985
发表时间:2022-12
期刊:Lithos
影响因子:3.5
作者:Xiang Zhou;Jian-Ping Zheng;Zengbao Huang;Zhi-Yong Li;Wei-Qi Zhang;Hong-Da Zheng;Q. Xiong;H. Dai
通讯作者:Xiang Zhou;Jian-Ping Zheng;Zengbao Huang;Zhi-Yong Li;Wei-Qi Zhang;Hong-Da Zheng;Q. Xiong;H. Dai
DOI:10.1093/petrology/egaa115
发表时间:2021-01
期刊:Journal of Petrology
影响因子:3.9
作者:Xiang Zhou;Jianping Zheng;Yibing Li;Hui Zhu;W. Griffin;S. O’Reilly
通讯作者:Xiang Zhou;Jianping Zheng;Yibing Li;Hui Zhu;W. Griffin;S. O’Reilly
DOI:10.19762/j.cnki.dizhixuebao.2022194
发表时间:2022
期刊:地质学报
影响因子:--
作者:周翔;郑建平;熊庆;刘文龙;Dick Henry J B
通讯作者:Dick Henry J B
国内基金
海外基金