Neoproterozoic tectonometamorphic history of the exotic Cuchilla Dionisio Terrane, Uruguay and its possible links with and continuation into SW Africa
Final Report Abstract
The Cuchilla Dionisio Terrane (CDT) basement in eastern Uruguay and equivalent terranes in the coastal areas of southeastern Brazil and eastern Argentina are a displaced fragment of southwest Africa. Felsic rift-related rocks of the CDT formed by crustal anatexis of the southern African Namaqua Province basement at the western margin of the Kalahari Craton (KC) during the initial stages of Rodinia break-up prior to opening of the Adamastor ocean at c. 780 Ma. A hightemperature metamorphic event occurred in the CDT at c. 655-640 Ma and was associated with subduction of this ocean underneath the western African margin and initiation of diachronous calcalkaline magmatism along a c. 1200 km long magmatic arc along this margin. Oceanic rocks from the CDT provide evidence that a first back-arc basin that had opened between this arc and the African margin must have already started to close at c. 628-625 Ma. This preceded further backarc magmatism further east, now evident in the Marmora Terrane of the Gariep Belt. In the late Ediacaran/early Cambrian the CDT was amalgamated to South America along the Sierra Ballena Shear Zone, which separates rocks of Río de la Plata Craton and KC affinities. This was associated with a transition from early Ediacaran subduction-related, arc-type magmatism to intraplate and, finally to late Ediacaran/early Cambrian collision-related igneous activity in the Uruguayan sector of the southern Dom Feliciano Belt.
Publications
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(2019). Neoproterozoic magmatic and metamorphic events in the exotic Cuchilla Dionisio Terrane, Uruguay, and possible correlations across the South Atlantic. Precam. Res. 320, 303-322
Will TM, Gaucher C, Ling XX, Li XH, Li QL, Frimmel HE
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(2020). Petrological, geochemical and isotopic data of Neoproterozoic rock units from Uruguay and South Africa: Correlation of basement terranes across the South Atlantic. Gondwana Res. 80, 12-32
Will TM, Höhn S, Frimmel HE, Gaucher C, le Roux PJ, Macey PH
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(2021). Ediacaran bimodal volcanism in the southernmost Dom Feliciano Belt, Uruguay: implications for the evolution of SW Gondwana. Lithos 406-407, 106539
Will TM, Gaucher C, Ling XX, le Roux PJ, Li XH, Li Q
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(2021). The Tapes Complex (Nico Pérez Terrane, Uruguay): constraining the Mesoproterozoic evolution of the Río de la Plata Craton. J. South Am. Earth Sci. 105, 102906
Gaucher C, Frei R, Samaniego L, Will TM, Chemale F, Gargiulo MF, Frei D, Poiré D, Ling XX, Li XH, Li QL
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(2022). Ediacarían to Cambrian tectonomagmatic events in the southern Dom Feliciano Belt, Uruguay: from a plate margin to an intraplate setting and the assembly of SW Gondwana. Gondwana Res.
Will TM, Gaucher C, Frimmel HE, Ling XX, Shi W, Li XH, Li Q
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(2022). The Río de la Plata Craton from Rodinia to Gondwana: new U-Pb-Hf-O data. X Congreso Uruguayo de Geología Montevideo
Gaucher C, Will TM, Finney, SC
