Precambrian crustal components, plutonic associations, plate environment of the Hercynian Fold Belt of central Europe: Indications from a Nd and Sr isotopic study
Precambrian crustal components, plutonic associations, plate environment of the Hercynian Fold Belt of central Europe: Indications from a Nd and Sr isotopic study
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DOI：
10.1007/bf00402106
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发表时间：
1988-02
影响因子：
3.5
通讯作者：
T. C. Liew;A.W Hofmann
中科院分区：
文献类型：
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作者：
T. C. Liew;A.W Hofmann
欧洲海西褶皱带变质岩、沉积物和花岗岩类的Nd模式年龄数据显示的明显地壳居住年龄从1.3 Ga到3.0 Ga不等，但主要在1.4-1.7 Ga之间。之前在西班牙北部和法国西北部的岛屿记录了2 Ga的基底地层，但除此之外，在褶皱带的南缘发现了古老的（~ 2 - 3 Ga）模式年龄。它们不能识别出古老的地层，但被解释为代表了从南方来源回收的太古宙早期元古代地壳成分。Nd数据，结合地表地质和最近的单粒锆石微探针数据，反对太古宙成分与新古生代地壳添加的二元混合，以产生主要的1.4-1.7 Ga模式年龄群。海西期欧洲主要由再循环元古代组成，但也有明显的新古生代和太古宙贡献。Nd和Sr同位素资料结合先前的化学和岩石学观测，可以识别出褶皱带东半部的大陆边缘i型花岗岩带向南渐变到内陆s型岩体。这种长英质岩体组合被用来推断海西期板块构造，包括褶皱带与南部母克拉通块体的连接，模式年龄数据表明可能是早元古宙-太古代。
Apparent crustal residence ages indicated by Nd model age data for metamorphic rocks, sediments and granitoids of the Hercynian Fold Belt of Europe vary from 1.3 Ga to 3.0 Ga, but are mainly in the range 1.4–1.7 Ga. 2 Ga basement inliers have been documented previously in northern Spain and islands off northwestern France but, in addition to these, old (∼2–3 Ga) model ages are found along the southern margin of the fold belt. These do not identify old inliers but are interpreted to represent Archeanearly Proterozoic crustal components recycled from a southern source. The Nd data, when considered together with the surface geology and recent single-grain zircon ion microprobe data, argue against a binary mixing of Archean components with new Palaeozoic crustal additions to generate the main 1.4–1.7 Ga model age population. Hercynian Europe comprise mainly recycled Proterozoic components although significant new Palaeozoic additions as well as Archean contributions are indicated.Nd and Sr isotopic data together with previous chemical and petrographic observations allow the recognition of a northern belt of continent margin I-type granitoids grading southwards to inner continent S-type plutons in the eastern half of the fold belt. This felsic plutonic association is used to infer a Hercynian plate configuration involving the attachment of the fold belt to a southern parent cratonic block that the model age data suggest may be of early Proterozoic-Archean age.