کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6431513 1348930 2011 17 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Alkaline magmatism in the Ponta Grossa Arch, SE Brazil: A review
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
Alkaline magmatism in the Ponta Grossa Arch, SE Brazil: A review
چکیده انگلیسی

The southern side of the Ponta Grossa Arch (PGA), a prominent NW-SE-trending tectonic feature extending over 600 km, was the site of important alkaline and alkaline-carbonatitic magmatic activity in Early and Late Cretaceous times. Occurrences associated with two of their lineaments (Guapiara and São Jerônimo-Curiúva) are quite variable in composition and include the following rock associations: ultramafic-mafic, syenitic, carbonatitic, fine-grained rocks (dikes), and fenites. Except for Tunas complex and some more evolved dikes outcropping in the area of Cerro Azul, which show sodic composition, the remaining rocks are clearly of potassic affinity. Crystal fractionation and accumulation processes played a major role in the formation and evolution of the PGA rocks, whereas crustal contamination or AFC seems to be restricted to the Cananeia lithotypes and a few dikes associated with the Juquiá and Tunas complexes. Furthermore, liquid immiscibility from silicate magmas is believed to be responsible for the formation of carbonatites in mostly alkaline and alkaline-carbonatitic complexes. The silicate rocks generally have higher Sri and lower Ndi, lying mainly in the enriched quadrant. Similar isotopic signatures are displayed by the associated carbonatites. TDM model ages indicate that the PGA alkaline magmatism appears to be related to a lithospheric mantle source that suffered important metasomatic events, leading to its enrichment by incompatible elements and H-C-F-rich fluids.

► Geological knowledge of Brazilian alkaline and alkaline-carbonatite occurrences. ► Early and Late Cretaceous alkaline magmatic activity in the Ponta Grossa Arch area. ► Petrological improvement of the alkaline magmatism in the South American Platform.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of South American Earth Sciences - Volume 32, Issue 2, August 2011, Pages 152-168
نویسندگان
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