The nodular granite of Castanheira, north central Portugal: origin of the nodules and evidence for diapiric mobilization of granite

Article Abstract:

The Hercynian Castaniera pluton of north-central Portugal is a small granitic intrusion containing an abundance of nodular granites rimmed with biotites. The nodules are believed to represent the original cavities in the topmost volatile-rich areas of the pluton. The biotite rims areinferred to be of magmatic origin as shown by the depletion of K and Rb in the host granite. Analysis of the shapes of the nodules have lead to a conclusion that the Castanheira pluton was a diapirically emplaced low viscocity facies of the larger granitic Serra de Freita pluton.

Portugal, Granite, Diapirs

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Emplacement and thermal metamorphism associated with the post-orogenic strath ossian pluton, grampian highlands, Scotland

Article Abstract:

The metasedimentary rocks of the Neoproterozoic Grampian and Appin groups were encroached upon by the multiphase Strath Ossian Pluton during the Silurian or early Devonian times. The emplacement that took place during the post-organic regional uplift and cooling followed the main ductile tectono-thermal history. Magmatization of the rocks in the northern part of the pluton with the generation of new ductile structures occurred due to the early emplacement of the diorite magma.

Scotland

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The Lower Cambrian Wrekin Quartzite and the age of its unconformity on the Ercall Granophyre

Article Abstract:

Acritarch specimens were found on the clay horizon above the unconformity between the Lower Cambrian Wrekin Quartzite and the Ercall Granophyre. The specimens were dated and used in relation to age determination of the granophyre intrusion and the unconformity. Stratigraphic findings and age determination have shown that the intrusion occurred 560 plus or minus one Ma. However the Cambrian Unconformity is younger than 533 plus or minus 13 Ma.

Analysis, Stratigraphic correlation, Geology, Stratigraphic, Correlation (Geology), Stratigraphy, Cambrian period, Quartzite

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