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| Trans Brazilian Lineament | |
|---|---|
| Name | Trans Brazilian Lineament |
| Type | Crustal-scale shear zone |
| Location | South America |
| Length | ~1,200–2,000 km |
| Period | Neoproterozoic–Paleozoic |
| Orogeny | Brasiliano orogeny |
| Notable | Transcurrent faulting, dextral shear sense |
Trans Brazilian Lineament The Trans Brazilian Lineament is a major crustal-scale shear zone and tectonic corridor that transects eastern and central Brazil, linking Proterozoic terranes and Neoproterozoic belts across the Brazilian Shield. It is a fundamental element of the Brasiliano orogeny, acting as a right-lateral transcurrent structure that accommodated crustal displacement during the assembly of Gondwana, and it intersects orogenic domains related to the Mantiqueira Mountains, Borborema Province, and São Francisco Craton. The lineament plays a central role in regional deformation, magmatism, and mineralization patterns and is a focal point for studies connecting South American and African Precambrian geology such as correlations with the West African Craton and the Kaapvaal Craton.
The Trans Brazilian Lineament is expressed as a series of steep, sinuous shear zones, fault corridors, and syntectonic granitoid belts extending roughly northeast–southwest across multiple tectonic provinces including the São Francisco Craton, Borborema Province, Araçuaí Orogen, and the Mantiqueira Orogen. Its map-scale trace links Mesoproterozoic and Neoproterozoic terranes, juxtaposes metamorphic complexes, and localizes late- to post-orogenic intrusions such as those related to the Itacolomi Granite and other Brasiliano plutons. The lineament’s kinematics and geometry are invoked in reconstructions of the Neoproterozoic closure of oceanic domains like the Adamastor Ocean and in paleogeographic models that position the Amazonian Craton relative to the Río de la Plata Craton.
Formed principally during the Neoproterozoic Brasiliano-Pan African orogenic cycle, the Trans Brazilian Lineament records interactions among continental blocks including the São Francisco-Congo Craton and adjacent microcontinents such as the Sergipano Belt and the Rio Preto da Eva Domain. Tectonically it represents a long-lived zone of weakness where pre-existing Mesoproterozoic structures were reactivated during continent–continent collisions associated with the amalgamation of Gondwana and the suturing of the West Gondwana margin. Thermal events tied to syn-tectonic magmatism, metamorphic overprinting, and crustal anatexis produced granitoids and migmatites that are emplaced along or adjacent to the lineament, commonly dated by U–Pb zircon methods used in studies of the Itabuna-Salvador-Curaçá Belt.
The lineament comprises anastomosing en echelon shear zones, brittle-ductile fault networks, mylonitic corridors, and strike-slip duplexes observable from regional mapping and aeromagnetic data. Kinematic indicators typically document dextral transpression with subordinate normal and reverse components, producing restraining bends, pull-apart basins, and synkinematic granitoid intrusions. The architecture includes lithological contrasts between high-grade gneiss terrains of the Araçuaí Belt and low-grade metasedimentary sequences of the Pernambuco-Alagoas Domain, producing rheological heterogeneity that localizes strain. Geophysical expression is marked by linear gravity gradients and magnetic lineaments continuous with mapped faults.
Timing constraints from U–Pb zircon, Sm–Nd isotopes, and Ar–Ar thermochronology place major activity along the lineament in the Neoproterozoic (c. 750–540 Ma) with earlier Mesoproterozoic inheritance (c. 1.6–1.0 Ga) and continued reactivation into the Paleozoic. Episodes of right-lateral shearing correlate with regional compressional pulses during the Brasiliano orogeny while subsequent extensional reactivation is recorded by basin formation and post-orogenic magmatism in the Cambro-Ordovician. Thermochronologic cooling histories from samples in the São Francisco Craton and adjacent belts constrain uplift and exhumation related to strike-slip tectonics and long-term rheological evolution.
The Trans Brazilian Lineament is a first-order control on mineral systems in eastern Brazil, channeling hydrothermal fluids and localizing ore deposition. Numerous gold, copper, iron, and rare-metal occurrences cluster along or near the lineament, including orogenic gold in shear-hosted veins, hydrothermal copper–gold mineralization associated with syn-tectonic granitoids, and Fe oxide deposits related to banded iron formation truncation. Exploration models reference the lineament when targeting shear-hosted gold systems in the Garimpo do Sul region, copper prospects in the Bahia sector, and pegmatite-hosted rare-earth element and tantalum deposits in the Minas Gerais area.
Regionally, the Trans Brazilian Lineament forms part of a network of Gondwana sutures and transform corridors that include analogous structures in Africa such as the Trans-Saharan Shear Zone and the Namaqua-Natal Belt. Correlations across the South Atlantic rift utilize the lineament to tie Neoproterozoic terranes of Brazil to conjugate margins in the West African Craton and Kaapvaal Craton, informing reconstructions of Paleozoic and Mesozoic break-up. Its role in accommodating lateral displacement influenced the geometry of orogenic belts like the Mantiqueira Orogen and affected subsequent intracontinental deformation during the formation of the South American Platform.
Investigation of the lineament evolved from early regional mapping by Brazilian geological surveys such as the Serviço Geológico do Brasil to integrated studies using U–Pb geochronology, Nd–Sr isotopic tracing, structural analysis, aeromagnetic and gravimetric surveys, and seismic profiling. Key contributions include syntheses by Brazilian and international researchers combining field structural data with geochronologic constraints from laboratories associated with institutions like the Universidade Federal de Minas Gerais, Universidade de São Paulo, and international centers in South Africa and Portugal. Modern approaches employ detrital zircon provenance studies, thermochronology, and numerical modeling to resolve slip histories, rheology, and links to Gondwana assembly, while ongoing exploration uses remote sensing and 3D geophysical inversion to map concealed segments.