RT Journal Article
T1 The Arequipa Massif of Peru: New SHRIMP and isotope constraintson a Paleoproterozoic inlier in the Grenvillian orogen
A1 Casquet, César
A1 Fanning, C.M.
A1 Galindo Francisco, Mª del Carmen
A1 Pankhurst, R.J.
A1 Rapela, Carlos W.
A1 Torres, P.
AB The enigmatic Arequipa Massif of southwestern Peru is an outcrop of Andean basement that underwentGrenville-age metamorphism, and as such it is important for the better constraint of Laurentia–Amazoniaties in Rodinia reconstruction models. U–Pb SHRIMP zircon dating has yielded new evidence on the evolutionof the Massif between Middle Paleoproterozoic and Early Paleozoic. The oldest rock-formingevents occurred in major orogenic events between ca. 1.79 and 2.1 Ga (Orosirian to Rhyacian), involvingearly magmatism (1.89–2.1 Ga, presumably emplaced through partly Archaean continental crust), sedimentationof a thick sequence of terrigenous sediments, UHT metamorphism at ca. 1.87 Ga, and late felsicmagmatism at ca. 1.79 Ga. The Atico sedimentary basin developed in the Late-Mesoproterozoic and detritalzircons were fed from a source area similar to the high-grade Paleoproterozoic basement, but alsofrom an unknown source that provided Mesoproterozoic zircons of 1200–1600 Ma. The Grenville-agemetamorphism was of low-P type; it both reworked the Paleoproterozoic rocks and also affected the Aticosedimentary rocks. Metamorphism was diachronous: ca. 1040 Ma in the Quilca and Camaná areas andin the San Juán Marcona domain, 940 ± 6 Ma in the Mollendo area, and between 1000 and 850 Ma in theAtico domain. These metamorphic domains are probably tectonically juxtaposed. Comparison with coevalGrenvillian processes in Laurentia and in southern Amazonia raises the possibility that Grenvillianmetamorphism in the Arequipa Massif resulted from extension and not from collision. The Arequipa Massifexperienced Ordovician–Silurian magmatism at ca. 465 Ma, including anorthosites formerly consideredto be Grenvillian, and high-T metamorphism deep within the magmatic arc. Focusedretrogression along shear zones or unconformities took place between 430 and 440 Ma.
PB Elsevier Science B.V., Amsterdam.
SN 0895-9811
YR 2010
FD 2010
LK https://hdl.handle.net/20.500.14352/41845
UL https://hdl.handle.net/20.500.14352/41845
LA eng
DS Docta Complutense
RD 1 may 2024