Tectonic Evolution of Brazilian Equatorial Continental Margin Basins

Ophiolite complexes are an important component of oceanic terranes in the northern Cordillera and constitute a significant amount of juvenile crust added to the Mesozoic Laurentian continental margin during Cordilleran orogenesis. Despite their tectonic importance, few systematic studies of these complexes have been conducted. Detailed studies of the pseudostratigraphy, age, geochemistry, and structural setting of ophiolitic rocks in the northern Cordillera indicate that ophiolites formed in Permian to Middle Triassic suprasubduction zone settings and were obducted onto passive margin sequences. Re-evaluation of ophiolite complexes highlights fundamental gaps in the understanding of the tectonic framework of the northern Cordillera. The previous inclusion of ophiolite complexes into generic 'oceanic' terranes resulted in significant challenges for stratigraphic nomenclature, led to incorrect terrane definitions, and resulted in flawed tectonic reconstructions.

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The Alegre Lineament and its role over the tectonic evolution of the Campos Basin and adjacent continental margin, Southeastern Brazil

Journal of South American Earth Sciences ◽

10.1016/j.jsames.2016.04.005 ◽

2016 ◽

Vol 69 ◽

pp. 226-242 ◽

Cited By ~ 4

Author(s):

Salomão Silva Calegari ◽

Mirna Aparecida Neves ◽

Felipe Guadagnin ◽

George Sand França ◽

Maria Gabriela Castillo Vincentelli

Keyword(s):

Continental Margin ◽

Tectonic Evolution ◽

Southeastern Brazil ◽

Campos Basin

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Tectonic Evolution of the South China Continental Margin

Gondwana Research ◽

10.1016/s1342-937x(05)70482-2 ◽

2001 ◽

Vol 4 (4) ◽

pp. 686-687

Author(s):

Zong-ting Liao ◽

Chen Yiao-kun ◽

Ma Ting-ting ◽

Li Yu-jia

Keyword(s):

Continental Margin ◽

South China ◽

Tectonic Evolution ◽

The South

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Silurian provenance variation in the Southern Uplands terrane, Scotland, assessed using neodymium isotopes and linked with regional tectonic evolution

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s0263593300008294 ◽

2000 ◽

Vol 91 (3-4) ◽

pp. 447-455 ◽

Cited By ~ 12

Author(s):

P. Stone ◽

J. A. Evans

Keyword(s):

Continental Margin ◽

Tectonic Evolution ◽

Abrupt Change ◽

Regional Variations ◽

Red Sandstone ◽

Neodymium Isotopes ◽

Compact Range ◽

Iapetus Ocean ◽

Regional Tectonic ◽

Proterozoic Basement

ABSTRACTThe progressive changes in the provenance of Silurian greywacke turbidites in the Southern Uplands terrane reflect geotectonic events at the Laurentian continental margin during closure of the Iapetus Ocean. In the northern Gala Group, juvenile andesitic detritus in some beds gives εNd values no lower than −4·2; more commonly, quartzo-feldspathic greywackes have εNd values in the −5·5 to −6·7 range, produced by the mixing of juvenile plutonic and Proterozoic basement detritus during arc unroofing. In the southern (younger) Gala Group, Proterozoic εNd values range down from −7·7 to −11·2 with only sporadic evidence for a juvenile component. An abrupt change is seen between the Gala Group and its tectonostratigraphical successor, the Hawick Group. In the latter, εNd values have a compact range between −4·7 and −6·6, indicating the renewed dominance of a more juvenile, plutonic provenance. Regional variations in the Sr/Rb ratio suggest that this was more evolved than the source of the Gala Group plutonic material. The Wenlock greywackes of the Riccarton Group have εNd values in the range −5·1 to −7·8, overlapping with the Hawick Group and with coeval greywackes from both the Midland Valley and Lakesman terranes. Overall, the data support proposals that the Iapetus Ocean had effectively closed by mid-Silurian times. Conversely, data from greywacke boulders in the basal Old Red Sandstone conglomerate of the Midland Valley terrane militate against its Wenlock juxtaposition with the Southern Uplands.

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The Piúma lineament, southern Espirito Santo: structural expression and tectonic significance

Brazilian Journal of Geology ◽

10.1590/2317-4889201620150038 ◽

2016 ◽

Vol 46 (4) ◽

pp. 531-546 ◽

Cited By ~ 2

Author(s):

Fernanda Silva Lourenço ◽

◽

Fernando Flecha de Alkmim ◽

Mário Neto Cavalcanti de Araújo ◽

Marco Antonio Thoaldo Romeiro ◽

...

Keyword(s):

Structural Analysis ◽

Continental Margin ◽

Tectonic Evolution ◽

Satellite Images ◽

Topographic Maps ◽

Espírito Santo ◽

Detailed Structural Analysis ◽

Campos Basin ◽

Tectonic Significance ◽

Espirito Santo

ABSTRACT: The Piúma lineament, located in the Southern Espírito Santo State, Brazil, is one of the most prominent linear morphostructural features of the northern Mantiqueira Province. The lineament stands out in satellite images and topographic maps, extending for about 70 km in a N50°W direction, between the towns of Iconha and Conceição do Castelo (Espírito Santo). In order to investigate the nature and role played by the Piúma lineament in the tectonic evolution of the Mantiqueira Province and adjacent Campos Basin, we carried out a detailed structural analysis based on fieldwork, as well as geophysical data processing and interpretation. The results we obtained indicate that the Piúma lineament is a brittle shear zone characterized by N50W-trending and SW-dipping shear fractures, faults and joints. These structures record two distinct and incompatible motions, thereby recording the operation of two tectonic regimes: NNE-SSW extension and E-W transtension. Comparing our results with the literature on the Southeastern Brazilian Continental Margin, we conclude that the Piúma lineament more likely developed after the Ediacaran Brasiliano orogenic event in response to an NNE-SSW extension, experiencing later a reactivation as normal dextral to dextral transtensional zone, probably in connection with the South Atlantic rifting in the Lower Cretaceous.

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