The Dam Feliciano Belt is a Pan-African mobile belt from the Ribeira orogen of southern Brazil. A detailed field and geochemical traverse along the BR392 road section between Pelotas and Cacapava do SuI identifies two major tectonic domains; the Pelotas Batholith and the Santana Metamorphic Belt, striking NNE-SSW parallel to the major foliation of the belts. The two belts are separated by a Triassic basin with flat lying red beds and interbedded andesites and rhyolites. The Santana Metamorphic Belt is a NW-verging fold belt with a metamorphosed shelf sequence of quartzites, marbles and graphitic schists and a polydeformed Lower Proterozic gneissic basement deformed during the Pan-African orogeny. Detailed mapping recognized four phases of deformation in the basement gneisses, three of which are recorded in the basement schists and cover sequence. There is also evidence of late NE-verging thrusting post-dating the formation unmetamorphosed Paleozoic sediments. Late extension caused NW-SE and NE-SW normal faulting. Metamorphism occurred contemporaneously with D2 and 03, and PT conditions for peak: metamorphism have been calculated as 8.6Kb and 60QOCwithin the basement schists corresponding to garnet growth during D3 deformation. Three phases of granite intrusion are recognized in the Santana Metamorphic Belt The Santana Granite (8oom.y.) represents the first phase intruding the basement and it is folded by 02 and 03. The Campinas Granite (Soom.y.) has a 03 foliation and the Cacapava Granite (474m.y.) is post-tectonic and intrudes the NW portion of the Santana Metamorphic Belt The Pelotas Batholith is almost entirely composed of granitoids of Pan-African age (600- 4S0m.y.). Both D2 and D3 are recognized in the batholith. A two fold subdivision based on geoc~emical and field criteria distinguishes the following categories of granitoid; foliated granitoids and unfoliated granites.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:305434 |
| Date | January 1990 |
| Creators | May, Sian Elizabeth |
| Publisher | Open University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://oro.open.ac.uk/54167/ |
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