Differential Phanerozoic evolution of cratonic and non-cratonic lithosphere from a thermochronological perspective : São Francisco Craton and marginal orogens (Brazil)

The Sao Francisco Craton (SFC) and its marginal Aracuai and Brasilia orogens exhibit a significant diversity in their lithospheric architecture. These orogens were shaped during the Neoproterozoic-Cambrian amalgamation of West Gondwana. The rigid cratonic lithosphere of the SFC and the relatively weak lithosphere of the Aracuai Orogen were disrupted during the Cretaceous opening of the South Atlantic Ocean, whereas the Brasilia Orogen remained in the continental hinterland. In earlier research, the thermal effects of the Phanerozoic reactivations in the shallow crust of the Aracuai Orogen have been revealed by low-temperature thermochronology, mainly by apatite fission track (AFT) analysis. However, analyses from the continental interior are scarce. Here we present new AFT data from forty-three samples from the Brasilia Orogen, the SFC and the Aracuai Orogen, far from the passive margin of the Atlantic coast (similar to 150 to 800 km). Three main periods of basement exhumation were identified: (i) Paleozoic, recorded both by samples from the SFC and Brasilia Orogen; (ii) Early Cretaceous to Cenomanian, recorded by samples from the Aracuai Orogen; and (iii) Late Cretaceous to Paleocene, inferred in samples from all domains. We compare the differential exhumation pattern of the different geotectonic provinces with their lithospheric strengths. We suggest that the SFC likely concentrated the Meso- Cenozoic reactivations in narrow weak zones while the Aracuai Orogen displayed a far-reachingMeso-Cenozoic deformation. The Brasilia Orogen seems to be an example of a stronger orogenic lithosphere, inhibiting reworking, confirmed by our new AFT data. Understanding the role of the lithosphere rigidity may be decisive to comprehend the processes of differential denudation and the tectonic-morphological evolution over Phanerozoic events. (C) 2021 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved

Avaliação das respostas tectônicas aos esforços fanerozóicos em terrenos orogénicos e cratônico do sudeste brasileiro: abordagem em termocronologia em traços de fissão em apatita

Submitted by Ana Fonseca ([email protected]) on 2020-02-27T15:03:39Z No. of bitstreams: 1 Tj_Master_ARcevo digital.pdf: 9980634 bytes, checksum: 9202433e6e7525be92bce1ebf650e6f9 (MD5)Rejected by Eliane Araujo ([email protected]), reason: Prezada Ana Carolina, Autoarquivamento REJEITADO! Coleção INCORRETA. Coleção CORRETA: Dissertações de MESTRADO Iniciar Novo Depósito: 1º Campo (SELECIONE): Trabalhos Acadêmicos - Dissertações de MESTRADO - Programa de Pós-Graduação em Geologia Qualquer dúvida, estamos à disposição. Atenciosamente, Eliane Araujo Repositório Institucional - UFMG Comunidade - TRABALHOS ACADÊMICOS Biblioteca Universitária - SB/UFMG 3409.4625 - 4620 - 5513 on 2020-03-17T19:31:29Z (GMT)Submitted by Ana Fonseca ([email protected]) on 2020-03-18T10:11:06Z No. of bitstreams: 1 Tj_Master_ARcevo digital.pdf: 9980634 bytes, checksum: 9202433e6e7525be92bce1ebf650e6f9 (MD5)Approved for entry into archive by Eliane Araujo ([email protected]) on 2020-03-24T17:55:20Z (GMT) No. of bitstreams: 1 Tj_Master_ARcevo digital.pdf: 9980634 bytes, checksum: 9202433e6e7525be92bce1ebf650e6f9 (MD5)Made available in DSpace on 2020-04-13T13:28:10Z (GMT). No. of bitstreams: 1 Tj_Master_ARcevo digital.pdf: 9980634 bytes, checksum: 9202433e6e7525be92bce1ebf650e6f9 (MD5) Previous issue date: 2020-02-21CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe geological setting of Southeast Brazil comprises the São Francisco Craton (SFC) and its marginal belts. These tectonic provinces were shaped during the Neoproterozoic–Cambrian orogenic cycle which resulted in the West Gondwana amalgamation. During the Cretaceous, the opening of the South Atlantic Ocean separated orogenic (e.g. Araçuaí Orogen) and cratonic (e.g. Northeast SFC) lands from their African counterparts, whereas some mobile belts were spared from this disruption (e.g. Brasília Belt). The Phanerozoic tectonic evolution of this area is rarely investigated, especially the portions far from the coast, since the SFC and its marginal belts have been part of a fairly stable continental region since the Cambrian. Here, fifty apatite fission-track (AFT) analyzes of samples from the Brasília Belt, the SFC, and the Araçuaí Orogen were reported. The AFT method is suitable to constrain time-temperature (t-T) paths of the rocks in the shallow crust (2 to 4 km), allowing the determination of cooling phases that may be related to tectonic reactivations. In the Brasília Belt, fourteen samples display the AFT central age ranging from 386 to 106 Ma and the mean track lengths (MTL) ranging between 10.8 to 13.5 μm. In the SFC, twelve samples yield the AFT central age ranging from 160 to 344 Ma and the MTL ranging from 11.2 to 12.7 μm. In the Araçuaí Orogen, twenty-four samples present the AFT central age ranging from 210 to 53 Ma and the MTL ranging from 11.5 to 13.5 μm. Thermal models were performed from the dataset using the Markov Chain Monte Carlo inversion. Three main periods of basement exhumation were identified: (i) Paleozoic, recorded by samples from the SFC and the Brasília Belt; (ii) Aptian to Cenomanian, recorded by samples from the Araçuaí Orogen; and (iii) Late Cretaceous to Paleocene, inferred in some samples from all domains. The Paleozoic phase seems to be triggered by extensive erosion that was probably induced by the tectonic extension during the rifting of continental crust in the context of tectonic subsidence of the intracontinental basins, mainly Paraná and Sanfranciscana basins. The Aptian to Cenomanian cooling was linked with the uplift triggered by the opening of the South Atlantic Ocean during the syn-rift phase. Finally, the widespread post-rift erosional event, i.e. Late Cretaceous to Paleocene, was connected with reactivations prompted by the interplay between flexural bending of the margin and the intraplate compressive stress transmitted from the plate boundaries. Over Phanerozoic events, the role of the lithosphere inheritance seems to be decisive to the processes of differential exhumation. The stiff lithosphere of SFC likely concentrated the Meso-Cenozoic reactivations in narrow weak zones (e.g. Recôncavo-Tucano-Jatobá rift) while the Araçuaí Orogen displayed a far-reaching Meso-Cenozoic deformation. The Brasília Orogen seems to be an example of a stronger orogenic lithosphere, inhibiting reworking, since it was not found evidence of strong Meso-Cenozoic tectonic activity in this belt.O arcabouço geológico do sudeste do Brasil é formado pelo Cráton São Francisco (CSF) e seus orógenos marginais. Essas províncias tectônicas foram constituidas e moldadas durante o ciclo orogênico Neoproterozóico-Cambriano, que resultou na amalgamação do Gondwana Ocidental. Durante o Cretáceo, a abertura do Oceano Atlântico Sul separou cinturões orogênicos (e.g. Orógeno Araçuaí) e cratons (e.g. porção nordeste do CSF) de suas contrapartes africanas. Por outro lado, alguns orógenos foram poupados da abertura (e.g. Orógeno Brasília). Uma vez que o CSF e seus cinturões marginais fazem parte de uma região continental considerada estável desde o Cambriano, a evolução tectônica Fanerozóica dessa área é raramente investigada, especialmente as porções distantes da costa. Neste trabalho, um total de quatorze amostras do Orógeno Brasília, doze amostras do CSF e vinte e quatro amostars do Orógeno Araçuaí são analisadas por meio de termocronologia, utilizando traço de fissão em apatita (TFA). O método de TFA é adequado para definir as trajetórias de temperatura-tempo (t-T) das rochas na crosta rasa (2 a 4 km), permitindo a determinação de fases de resfriamento que podem estar relacionadas a eventos de reativação tectônica. No Orógeno Brasília, as idades centrais de TFA das amostras analisadas variaram de 386 a 106 Ma e os comprimentos médios dos traços (CMT) variaram entre 10,8 e 13,5 μm. No CSF, as idades centrais de TFA variaram de 160 a 344 Ma e o CMT variaram de 11,2 a 12,7 μm. No Orógeno Araçuaí, as amostras apresentaram as idades centrais de TFA entre 210 a 53 Ma e o CMT variando de 11,5 a 13,5 μm. A partir do conjunto de dados termocronológicos foi possível executar a inversão de Markov Chain Monte Carlo e determinar modelos térmicos (t-T). Foram identificados três períodos principais de exumação do embasamento dessas províncias tectônicas: (i) Paleozóico, registrado por amostras do CSF e do Orógeno Brasília; (ii) Aptiano a Cenomaniano, registrado por amostras do Orógeno Araçuaí; e (iii) Cretáceo tardio ao Paleoceno, inferido em amostras de todos os domínios. A fase Paleozóica parece ter sido desencadeada por uma erosão extensa que provavelmente foi induzida pela extensão tectônica durante o fraturamento da crosta continental no contexto de subsidência das bacias intracontinentais, principalmente as bacias do Paraná e Sanfranciscana. O resfriamento do Aptiano ao Cenomaniano foi relacionado ao soerguimento desencadeado pela abertura do Oceano Atlântico Sul durante a fase sin-rifte. Por fim, o evento erosivo generalizado durante o Cretáceo tardio ao Paleoceno, foi conectado às reativações tectônicas induzidas pela interação entre a flexão da margem continental e os esforços compressivos intraplaca, transmitidos a partir dos limites da placa Sul-Americana. Nos eventos Fanerozóicos, o papel da herança litosférica parece ter sido decisiva nos processos de exumação diferencial. A litosfera rígida do CSF provavelmente concentrou as reativações Meso-Cenozóicas em zonas de fraqueza estreitas (e.g. rift Recôncavo-Tucano-Jatobá) enquanto que o Orógeno Araçuaí exibiu uma extensa deformação Meso-Cenozóica. No Orógeno Brasília não foram encontradas evidências de forte atividade tectônica Meso-Cenozóica, corroborando hipóteses anteriores de que esse orógeno apresenta uma litosfera orogênica enrigecida que inibe o retrabalhamento

Differential exhumation of cratonic and non-cratonic lithosphere revealed by apatite fission-track thermochronology along the edge of the São Francisco craton, eastern Brazil

Lithosphere of cratons and orogens generally reacts differently to tectonic events. Although these differences are mostly clear during the orogenic phases, understanding how they respond to tectonic reactivation is still challenging. Here, we report the first detailed apatite fission-track (AFT) study pinpointing the gradual transition between cratonic and orogenic lithosphere, using the case study of the São Francisco craton (SFC) and the adjacent Araçuaí-West Congo Orogen (AWCO), eastern Brazil. The collision that built the AWCO partially affected the inherited rift structures of the Paramirim Aulacogen, embedded in the São Francisco-Congo paleocontinent. Our data reveal a differential Phanerozoic exhumation between closely interspaced areas affected and not affected by the AWCO deformation. Samples from the SFC present slow and protracted basement cooling during the Phanerozoic, while samples from the orogen display rapid exhumation since the Eocene. An intermediate ~ N–S zone of c.40 km shows lower magnitude basement cooling during the Cenozoic, possibly because the propagation of AWCO deformation decreases towards the craton interior. Within the orogen, the Rio Pardo salient is the main reactive structure and probably results from the deformation of a master fault, inherited from its precursor rift. Here, we show how the magnitude of Phanerozoic denudation may be deeply associated with previous events of lithosphere weakening

Contrasting thermal histories for the Indian passive margins during syn‐ and post‐Gondwana break‐up: Insights from apatite fission‐track thermochronology

First published: 07 September 2022.New and published apatite fission-track data provides evidence for differential exhumation between the eastern and western passive margins of southern India. The eastern margin records significant Late Jurassic to Early Cretaceous rifting-triggered exhumation in response to Gondwana break-up and minor Cenozoic cooling. In contrast, Meso–Cenozoic rifting and posterior tectonic events did not deeply exhume the basement of the western margin. The anomalous thick crust of the Western Dharwar Craton might explain why Mesozoic deformation in this area was subdued. In addition, the Cenozoic eastward tilting of the Indian plate and the onset of Bengal Fan sedimentation ca. 23 Ma allowed accumulation of thick sedimentary sequences in the eastern coastal basins, probably inducing a flexural response of fault reactivation on the eastern margin. More generally, we demonstrate the influence of lithospheric strength and post-rifting sedimentation to the exhumation history of passive margins.Ana Fonseca, Stijn Glorie, Zhiyuan He, Tejpal Singh, Johan De Grav

Reply to the comment on 'Devonian to Permian post-orogenic denudation of the Brasília Belt of West Gondwana : insights from apatite fission track thermochronology' by Alessandretti and Warren, 2021

Here we reply to the comment by Alessandretti and Warren, (2021) on the paper "Devonian to Permian postorogenic denudation of the Brasilia Belt of West Gondwana: insights from apatite fission track thermochronology " by Fonseca et al. (2020). We have the impression that many of the remarks, at least to some extent stem from a misunderstanding of our manuscript, also considering that they did not propose any alternative hypothesis for interpretation of our results presented in the aforementioned paper. We, thus, reiterate our interpretations from our low-temperature thermochronology data. The basement of the Brasilia Belt was subject to a significant exhumation during the Devonian to the Permian through erosion, and was likely a source area for detrital sediments deposited in parts of the northeastern Paran & PRIME;a Basin at that time. Apatite fission-track data show that Meso-Cenozoic events had limited effect on post-orogenic exhumation of the Brasilia Belt, in contrast to e.g. the Aracuai Belt

A re-evaluation of the Meso-Cenozoic thermo-tectonic evolution of Bogda Shan (Tian Shan, NW China) based on new basement and detrital apatite fission track thermochronology

Bogda Shan is a mountain belt located at the eastern extremity of the Chinese Tianshan and records a complex and debated exhumation history. Previous studies have reported a young Cenozoic thermal history for the exhumation of Bogda Shan, which is in conflict with the observation of preserved Mesozoic erosion surfaces in the area. This study re-evaluates the Meso-Cenozoic thermo-tectonic evolution of Bogda Shan using apatite fission track (AFT) thermochronology. Palaeozoic basement (meta-sandstone) samples collected from the northern and southwestern flanks of the mountain ranges reveal apparent Mesozoic AFT ages ranging from ~202 Ma to ~97 Ma. Inverse thermal history modelling results reveal slow to moderate basement cooling during the early Mesozoic, corresponding to relatively low levels of exhumation. This accounts for the preservation of low-relief Mesozoic peneplanation surfaces recognized at elevations of ~3500–4000 m. None of the presented AFT data and thermal history models show any evidence for significant deep Cenozoic exhumation. In the neighbouring Junggar Basin, a Middle Jurassic sandstone sample records partial resetting of the AFT system during the Cretaceous. This observation conflicts with previous data (from the same Jurassic strata) where complete resetting of the AFT clock during the Cenozoic was suggested. Furthermore, Lower Cretaceous and Palaeogene sediments from the Turpan-Hami Basin show non-reset detrital AFT age populations of ~197, ~135, and ~104 Ma, which are coincident with the main pulses of exhumation recorded in the Chinese North Tianshan. Based on a comprehensive summary of the published data, we argue for a Mesozoic building of the Bogda–Balikun–Harlik mountain chain in the eastern Chinese Tianshan. Subsequent Cenozoic exhumation must have been relatively modest at most (<2 km) as it was not recorded by AFT thermochronology