Second-stage Caribbean Large Igneous Province volcanism: The depleted Icing on the enriched Cake
Second-stage Caribbean Large Igneous Province volcanism: The depleted Icing on the enriched Cake
复制标题
第二阶段加勒比大型火成岩省火山活动：丰富蛋糕上的耗尽糖霜
DOI：
10.1016/j.chemgeo.2019.01.004
复制
发表时间：
2019
期刊：
影响因子：
3.9
通讯作者：
Dieter
中科院分区：
文献类型：
--
作者：
Dürkefälden;Hoernle;Folkmar;Werner;Reinhard;Garbe-Schönberg;Dieter
一个长期存在的问题是，西加勒比海的下巴拿马海隆是代表薄大陆地壳还是加勒比大火成岩省（CLIP）的一部分。在“流星”号考察船M81/2巡航期间，对包括赫斯陡崖在内的下关海隆东北部进行了广泛取样。只发现了火山岩和碳酸盐岩，没有发现变质岩或与大陆地壳密切相关的岩石，这表明至少最上层的基底是火山岩，属于一个火山省，可能是CLIP。我们提供了一个全面的地球化学数据集，包括火山岩的常量和微量元素和Sr-Nd-Hf-Pb双穗同位素比值，。玄武岩在地球化学上可分为两类：1）亏损型和2）富集型。绝大多数为亏损型，MgO含量为6- 9wt%，不相容元素（如（La/Yb）N= 0.15-0.76，（La/Sm）N= 0.21-0.65）和放射性同位素（如εNdi= 8.9-11.0，εHfi= 13.6 ~ 16.5，206 Pb/204 Pbi = 18.28-18.98）比值严重亏损。次级富集组玄武岩的MgO含量为5- 8wt%，仅采自赫斯陡崖中部的下部。这些岩石具有富集的不相容元素（（La/Sm）N= 1.15-1.60，（La/Yb）N= 1.40-2.57）和同位素（εNdi= 7.52-8.34，εHfi= 12.6- 12.9，206 Pb/204 Pbi = 18.87-19.07）比值，类似于E-MORB。根据206 Pb/204 Pb、143 Nd/144 Nd和176 Hf/177 Hf的组合数据，该亏损群与太平洋和大西洋MORB不同。它与高度贫化的戈尔戈纳科马提岩相似，但不完全相同，被认为是在CLIP事件期间产生的，以及在中美洲太平洋边缘增生的贫化的加拉帕戈斯热点轨道熔岩。在赫斯陡崖上钻取的岩石的年龄约为81 Ma，晚于主要的CLIP阶段（95-83 Ma），表明至少川隆的东北部是在后来的火山事件中形成的。在CLIP主阶段之后的岩石圈变薄，被认为触发了仍然异常热的、部分熔融或未熔融的CLIP地幔物质的上涌，形成了年轻的亏损熔岩群。我们的调查表明，第二阶段熔融产生亏损组合物在形成的海洋大火成岩省，最近已提出的Manihiki高原，是一个更常见的过程比原来认为的。
A long-standing question has been whether the Lower Nicaraguan Rise in the western Caribbean Sea represents thinned continental crust or is part of the Caribbean Large Igneous Province (CLIP). During the R/V Meteor cruise M81/2, the northeastern part of the Lower Nicaraguan Rise including the Hess Escarpment was extensively sampled. Only volcanic and carbonate rocks were recovered and no metamorphic rocks or rocks with continental crustal affinities, indicating that at least the uppermost basement is volcanic and belongs to a volcanic province, probably the CLIP. We provide a comprehensive geochemical dataset, including major and trace elements and Sr-Nd-Hf-Pb double spike isotope ratios, for the volcanic rocks. The basalts are geochemically subdivided into two groups: 1) depleted and 2) enriched. The majority belong to the depleted group with 6–9 wt% MgO and highly depleted incompatible element (e.g. (La/Yb)N= 0.15–0.76, (La/Sm)N= 0.21–0.65) compositions and depleted radiogenic isotope (e.g. εNdi= 8.9–11.0, εHfi= 13.6–16.5,206Pb/204Pbi= 18.28–18.98) ratios. The subordinate enriched group basalts have 5–8 wt% MgO and were solely recovered from the lower part of the central Hess Escarpment. These rocks possess enriched incompatible element ((La/Sm)N= 1.15–1.60, (La/Yb)N= 1.40–2.57) and isotopic (εNdi= 7.52–8.34, εHfi= 12.6–12.9,206Pb/204Pbi= 18.87–19.07) ratios resembling E-MORB. The depleted group is distinct from Pacific and Atlantic MORB based on combined206Pb/204Pb,143Nd/144Nd and176Hf/177Hf data. It is similar, but not identical to the highly depleted Gorgona komatiites, thought to be generated during the CLIP event, and depleted Galápagos hotspot track lavas accreted to the Pacific margin of Central America. Ages of ~81 Ma from rocks drilled on the Hess Escarpment postdate the main CLIP phase (95-83 Ma), and indicate that at least the northeastern part of the Nicaraguan Rise formed during a later volcanic event. Lithospheric thinning after the main CLIP phase is suggested to have triggered upwelling of still anomalously hot, partially-melted or unmelted CLIP mantle material to form the younger depleted group of lavas. Our investigations imply that second-stage melting to generate depleted compositions during formation of oceanic large igneous provinces, as has been recently proposed for the Manihiki Plateau, is a more common process than originally thought.
登录
查看更多内容
影响因子：
5.8
作者：
Hoernle, K;Hauff, F;van den Bogaard, P
通讯作者：
van den Bogaard, P
渐新世-中新世期间北尼加拉瓜隆起的演化：被环境因素淹没
影响因子：
2.8
作者：
M. Mutti;A. Droxler;A. Cunningham
通讯作者：
A. Cunningham
加勒比高原的复杂历史：南伊斯帕尼奥拉岛贝阿塔海岭的岩石学、地球化学和地质年代学
DOI：
--
发表时间：
2000
期刊：
The Journal of geology
影响因子：
--
作者：
S. Révillon;E. Hallot;N. Arndt;C. Chauvel;R. Duncan
通讯作者：
R. Duncan
大西洋的开放和加勒比海的起源
影响因子：
64.8
作者：
M. M. Ball;C. Harrison;P. R. SUPKO
通讯作者：
P. R. SUPKO
贝亚塔海岭的年龄和地球化学：加勒比大型火成岩省主相（~89Ma）的初级形成
影响因子：
3.5
作者：
A. Dürkefälden;K. Hoernle;F. Hauff;J;P. Bogaard;R. Werner
通讯作者：
R. Werner