The formation of Pangea

Abstract

The making of Pangea is the result of large-scale amalgamation of continents and micro-continents, which started at the end of the Neoproterozoic with the formation of Gondwana. As pieces were added to Gondwana on its South-American, Antarctica and Australia side, ribbon-like micro-continents were detached from its African and South-Chinese side: Cadomia in the late Neoproterozoic, Avalonia and Hunia in the Ordovician, Galatia in the Devonian and Cimmeria in the Permian. Cadomia was re-accreted to Gondwana, but the other ribbon-continents were accreted to Baltica, North-China, Laurussia or Laurasia. Finding the origin of these numerous terranes is a major geological challenge. Recently, a global plate tectonic model was developed together with a large geological/geodynamic database, at the Lausanne University, covering the last 600 Ma of the Earth's history. Special attention was given to the placing of Gondwana derived terranes in their original position, using all possible constraints. We propose here a solution for the Variscan terranes, another paper deals with the Altaids. The Galatian super-terrane was detached from Gondwana in the Devonian, during the opening of Paleotethys, and was quickly separated into four sub-terranes that started to bypass each other. The leading terranes collided at the end of the Devonian with the Hanseatic terrane detached from Laurussia. In the Carboniferous, Gondwana started to impinge onto the amalgamated terranes, creating the Variscan chain and the Pangean super-continent. East of Spain Paleotethys remained opened until the Triassic, subducting northward under Laurasia. Roll-back of the Paleotethyan slab triggered the collapse of most of the European Variscan orogen, which was replaced by series of Permian rifts, some of them becoming oceanized back-arc basins during the Triassic. Major force changes at the Pangean plate limits at the end of the Triassic provoked its break-up, through the opening of the proto-Caribbean, central-Atlantic, Alpine-Tethys oceanic seaways.

Geophysical evidence of pre-sag rifting and post-rifting fault reactivation in the Parnaíba basin, Brazil

“…Key: red lines represent shear zones; blue lines represent continents; thick black lines represent West Gondwana continental blocks. Adapted from Cordani et al (2013) and Stampfli et al (2013). and featured relatively slow, long-lived subsidence events (∼ 355 Myr in duration) from the Silurian to the late Cretaceous (Góes and Feijó, 1994). Preceding the sag sedimentation, fault reactivation of the Brasiliano shear zones controlled the formation of a set of rift basins (Jaibaras, Cococi, and others).…”

Geophysical perspective on the structural interference zone along the Neoproterozoic Brasília and Ribeira fold belts in West Gondwana

“…In contrast to the Western part of the South American Platform, the Brazilian crust remained mostly absent of deformation throughout Phanerozoic, except for the formation of several sedimentary basins, and magmatic events developed by far-field stress deformation from the Andean chain (Stampfli et al 2013, Granot & Dyment 2015. From Neo-Ordovician to Neo-Cretaceous the siliciclastic Paraná intra-cratonic basin is formed over Precambrian crust (mainly Paranapanema Block and adjacent fold belts), also hosting the expressive Serra Geral Formation basic magmatism (dykes, sills and basalts) from Lower Cretaceous (Zalan et al 1990, Peate 1997.…”

Aspects of geodiversity of Palaeozoic limestones in the Black Mountains of southern France

“…Thereafter, a detailed geological survey of the local Silurian was carried out by Marcel cHRIStIAN GIUStI Thoral (1935), whose work was subsequently clarified by André Centène (1975Centène ( , 1977 through the study of Conodonts, and by Jean-Pierre Prian (1980) for lithostratigraphy and geological mapping (the boutonnières of Le Cros, Laime's river, and the Rance Valley west and north of Mounes). It must be recalled that the Silurian of Murasson (NS of the Black Mountains) is very different from that of the Laurens-Cabrières area on the Southern Side (Chaubet 1937), a fact not really astonishing given the great complexity of the western peri-Gondwana margin paleogeography (see the position of the Maures-Black Mountains block on the reconstructions by Stampfli et al 2013) and the intensity of tectonics in the outer zone of the Variscan Belt (Faure et al 2014). …”