TY - JOUR
T1 - West Gondwana orogenies and Pangaea break-up
T2 - thermotectonic effects on the southernmost Mantiqueira Province, Brazil
AU - Silveira Luiz Machado, Joao Pacifico
AU - Jelinek, Andrea Ritter
AU - Bicca, Marcos Muller
AU - Stephenson, Randell
AU - Genezini, Frederico Antonio
N1 - Acknowledgements
We thank P. W. Reiners and his team at the Baja Arizona Radiogenic Helium Dating Laboratory (USA) for the (U–Th)/He analyses and assistance. We are grateful for the suggestions of L. A. Hartmann and Chong Ma, which significantly improved the paper.
Funding
The authors gratefully acknowledge the support from Shell Brasil through the ‘BG05: UoA-UFRGS-SWB Sedimentary Systems’ project at UFRGS, the strategic importance of the support given by ANP through the R&D levy regulation, and the CNPq scholarship (SWE 204254/2017-5) during the exchange period at the University of Aberdeen.
PY - 2019/11
Y1 - 2019/11
N2 - Through the joint use of apatite fission tracks (AFT) and (U–Th)/He analysis in apatite (AHe) and zircon (ZHe), we evaluate the thermotectonic evolution of the Sul-Rio-Grandense Shield (SRGS), southernmost Mantiqueira Province, Brazil. Formed during the assembly of West Gondwana (Neoproterozoic), the shield comprises four tectonostratigraphic terranes separated by regional faults and shear zones. The central and eastern terranes present Mesozoic AFT ages, whereas the western terrane ages are mostly late Paleozoic. AHe ages show considerable dispersion, although most are Mesozoic. ZHe ages from the east are early Permian, whereas the west presents Devonian ages. Inverse thermal modelling indicates a Devonian to Carboniferous cooling phase in the west, time correlated with orogenies occurring at the SW margin of Gondwana, which affected the regional geodynamics and are possibly linked to limited uplift of the shield. From the Permian to Jurassic a major cooling phase took place in the SRGS, probably related to lithosphere thinning and uplift preceding the South Atlantic rifting. Samples closer to the Atlantic coast suggest a subtle reheating after this event, provisionally linked to a geothermal disturbance related to ocean opening and associated magmatism. A final post-Paleocene cooling phase towards surface conditions affected the entire SRGS.
AB - Through the joint use of apatite fission tracks (AFT) and (U–Th)/He analysis in apatite (AHe) and zircon (ZHe), we evaluate the thermotectonic evolution of the Sul-Rio-Grandense Shield (SRGS), southernmost Mantiqueira Province, Brazil. Formed during the assembly of West Gondwana (Neoproterozoic), the shield comprises four tectonostratigraphic terranes separated by regional faults and shear zones. The central and eastern terranes present Mesozoic AFT ages, whereas the western terrane ages are mostly late Paleozoic. AHe ages show considerable dispersion, although most are Mesozoic. ZHe ages from the east are early Permian, whereas the west presents Devonian ages. Inverse thermal modelling indicates a Devonian to Carboniferous cooling phase in the west, time correlated with orogenies occurring at the SW margin of Gondwana, which affected the regional geodynamics and are possibly linked to limited uplift of the shield. From the Permian to Jurassic a major cooling phase took place in the SRGS, probably related to lithosphere thinning and uplift preceding the South Atlantic rifting. Samples closer to the Atlantic coast suggest a subtle reheating after this event, provisionally linked to a geothermal disturbance related to ocean opening and associated magmatism. A final post-Paleocene cooling phase towards surface conditions affected the entire SRGS.
U2 - 10.1144/jgs2019-018
DO - 10.1144/jgs2019-018
M3 - Article
VL - 176
SP - 1056
EP - 1075
JO - Journal of the Geological Society
JF - Journal of the Geological Society
SN - 0016-7649
IS - 6
ER -