当前位置: X-MOL 学术J. Petrol. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Mantle Dynamics of the Central Atlantic Magmatic Province (CAMP): Constraints from Platinum Group, Gold and Lithophile Elements in Flood Basalts of Morocco
Journal of Petrology ( IF 3.5 ) Pub Date : 2019-08-01 , DOI: 10.1093/petrology/egz041
Christian Tegner 1 , Sandra A T Michelis 1 , Iain McDonald 2 , Eric L Brown 1 , Nasrrddine Youbi 3, 4 , Sara Callegaro 5 , Sofie Lindström 6 , Andrea Marzoli 7
Affiliation  

Mantle melting dynamics of the Central Atlantic Magmatic Province (CAMP) are constrained from new platinum group element (PGE), rare earth element (REE), and high field strength element (HFSE) data and geochemical modelling of flood basalts in Morocco. The PGE are enriched similarly to flood basalts of other large igneous provinces. The magmas did not experience sulphide saturation during fractionation and were therefore fertile. The CAMP province is thus prospective for PGE and Gold mineralisation. The Pt/Pd ratio of the Moroccan lavas indicates that they originated by partial melting of the asthenospheric mantle, not the subcontinental lithospheric mantle. Mantle melting modelling of PGE, REE and HFSE suggests: (1) that the mantle source for all the lavas was dominated by primitive mantle and invariably included a small proportion of recycled continental crust (<8%); (2) the mantle potential temperature was moderately elevated (c. 1430 °C) relative to ambient mantle; (3) intra-lava unit compositional variations are likely a combined result of variable amounts of crust in the mantle source (heterogeneous source) and fractional crystallisation; (4) mantle melting initially took place at depths between c. 110 km and c. 55 km and became shallower with time (c. 110 km to c. 32 km depth); and (5) the melting region appears to have changed from triangular to columnar with time. These results are best explained by melting of asthenospheric mantle that was mixed with continental sediments during the assembly of Pangaea, then heated and further mixed by convection while insulated under the Pangaea supercontinent, and subsequently melted in multiple continental rift systems associated with the breakup of Pangaea. Most likely the CAMP volcanism was triggered by the arrival of a mantle plume, although plume material apparently was not contributing directly (chemically) to the magmas in Morocco, nor to many other areas of CAMP.

中文翻译:

中大西洋岩浆区 (CAMP) 的地幔动力学:摩洛哥溢流玄武岩中铂族、金和亲石元素的约束

中大西洋岩浆区 (CAMP) 的地幔熔融动力学受到新铂族元素 (PGE)、稀土元素 (REE) 和高场强元素 (HFSE) 数据以及摩洛哥溢流玄武岩地球化学模型的约束。PGE 的富集类似于其他大型火成岩省份的泛滥玄武岩。岩浆在分馏过程中没有经历硫化物饱和,因此是肥沃的。因此,CAMP 省具有 PGE 和金矿化的前景。摩洛哥熔岩的 Pt/Pd 比率表明它们起源于软流圈地幔的部分熔化,而不是次大陆岩石圈地幔。PGE、REE 和 HFSE 的地幔熔融模型表明:(1) 所有熔岩的地幔源均以原始地幔为主,且均含有少量再生大陆地壳(<8%);(2) 地幔位温相对于环境地幔适度升高(c. 1430 °C);(3) 熔岩单元内部成分的变化可能是地幔源(非均质源)中地壳数量变化和分步结晶的综合结果;(4) 地幔熔融最初发生在 c 之间的深度。110 公里和 c。55 公里,随着时间的推移变得更浅(深度约 110 公里至约 32 公里);(5) 熔化区似乎随着时间从三角形变为柱状。这些结果最好通过在 Pangaea 组装期间与大陆沉积物混合的软流圈地幔的融化来解释,然后加热并通过对流进一步混合,同时在盘古超大陆下绝缘,随后在与盘古分裂相关的多个大陆裂谷系统中融化。最有可能的 CAMP 火山活动是由地幔柱的到来引发的,尽管柱状物质显然没有直接(化学)贡献给摩洛哥的岩浆,也没有对 CAMP 的许多其他地区产生影响。
更新日期:2019-08-01
down
wechat
bug