Post-collisional alkaline magmatism as gateway for metal and sulfur enrichment of the continental lower crust
Post-collisional alkaline magmatism as gateway for metal and sulfur enrichment of the continental lower crust
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DOI：
10.1016/j.gca.2017.11.009
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发表时间：
2018-02-15
影响因子：
5
通讯作者：
Thi-Hao Bui
中科院分区：
文献类型：
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作者：
Fiorentini, Marco L.;LaFlamme, Crystal;Thi-Hao Bui
侵入下地壳的镁铁质和超镁铁质岩浆可以保存金属和硫从岩石圈地幔转移到下大陆地壳的证据。在这里，我们关注意大利西北部伊夫雷亚带的一系列超镁铁质碱性岩筒，它暴露出深埋(6-11kbar)的混合质变沉积岩，被马菲克杂岩的大量玄武岩岩浆侵入，这是一个主要的地壳底侵事件，通过锆石上的U/PbCA-IDTIMS准确地测定了286.8 Ma+/-0.4 Ma。这些超镁铁质管道形成于Mafic杂岩和100至300米宽的富含堆积物的管道。它们是水化和碳酸盐化的，具有异常高的不相容元素浓度，并含有气泡状和半块状的Ni-Cu-PGE硫化物矿化。硫化物呈粗大的晶间结核(>；10 mm)和小的粒内气泡(
Mafic and ultramafic magmas that intrude into the lower crust can preserve evidence for metal and sulfur transfer from the lithospheric mantle into the lower continental crust. Here we focus on a series of ultramafic, alkaline pipes in the Ivrea Zone (NW Italy), which exposes deeply buried (6-11 kbar), migmatitic metasedimentary rocks intruded by voluminous basaltic magmas of the Mafic Complex, a major crustal underplating event precisely dated via U/Pb CA-IDTIMS on zircon at 286.8 +/- 0.4 Ma. The ultramafic pipes postdate the Mafic Complex and from 100 to 300 m wide cumulate-rich conduits. They are hydrated and carbonated, have unusually high incompatible element concentrations and contain blebby and semi-massive Ni-Cu-PGE sulfide mineralisation. The sulfides occur as coarse intergranular nodules (>10 mm) and as small intragranular blebs (