A critical discussion of the subduction-collision model for the Neoproterozoic Aracuai-West Congo orogen

Autor(es)

Fossen, Haakon ^[1] ; Cavalcante, Carolina ^{[2, 3]} ; Konopasek, Jiri ^{[2, 4]} ; Meira, Vinicius T. ^[5] ; de Almeida, Renato Paes ^[6] ; Hollanda, Maria Helena B. M. ^[6] ; Trompette, Roland ^[7]

Afiliação do(s) autor(es)

^[1] Univ Bergen, Museum Nat Hist, Dept Earth Sci, Postboks 7803, N-5020 Bergen - Norway

^[2] UiT Arctic Univ Norway, Postboks 6050 Langnes, N-9037 Tromso - Norway

^[3] Univ Fed Parana, Dept Geol, Ave Coronel Francisco H Santos 100, BR-81531980 Curitiba, Parana - Brazil

^[4] Czech Geol Survey, Klarov 3, Prague 11821 1 - Czech Republic

^[5] Univ Estadual Campinas, Inst Geociencias, Campinas - Brazil

^[6] Univ Sao Paulo, Inst Geociencias, Rua Lago 562, BR-05508900 Sao Paulo, SP - Brazil

^[7] 35 Rue Pascal, F-75013 Paris - France

• Tipo de documento: Artigo Científico
• Fonte: Precambrian Research; v. 343, JUL 2020.
• Citações Web of Science: 0

Resumo

The Neoproterozoic Aracuai-West Congo orogen in Brazil and Congo represents a branch of the Brasiliano/Pan-African orogenic system that is considered to terminate northward into a confined cratonic environment defined by the horseshoe-shaped pre-Atlantic Sao Francisco-Congo craton. The prevailing interpretation is that this orogen formed as a result of 50 m.y. of subduction leading to a classical continent-continent collision. This subduction-collision model hinges on interpretation of 630-580 Ma granitoids in the core of the orogen as being arc-related, and of locally exposed mafic and ultramafic metamorphic rocks as being ophiolitic. We show that when tested beyond geochemical signature, the model has fundamental problems that cannot be accounted for. In particular, there is an insurmountable oceanic space problem in this confined setting that is overlooked in most of the current literature. There are also problems with subduction initiation, lack of unambiguous evidence for oceanic crust, no trace of any high-P metamorphism and the abrupt termination of an ocean with no realistic way to transfer the large amount of oceanic opening displacement and subsequent convergence required by the model. We conclude that the prevailing subduction-collision model cannot possibly work and argue that the existing data are more consistent with hot intracontinental orogeny. We stress the importance of building tectonic models on more than one type of data, making realistic restorations and palinspastic reconstructions, and taking into account modern geotectonic knowledge. (AU)

• Processo FAPESP: 15/23572-5 - De orogenias a rifteamentos: um estudo de cinturões orogênicos brasileiros e uma comparação com cinturões escandinavos do Atlântico Norte e margens continentais
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