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Geoscience Frontiers 2019年第2期10卷 611-628页

作者： Mathias Schannor cristiano lana Marco A.Fonseca Applied Isotope Research Group Department of GeologyUniversidade Federal de Ouro Preto

Detrital zircon U-Pb geochronology combined with Hf isotopic and trace element data from metasedimentary rocks of the Aracuai Belt in southeastern Brazil provide evidence for break-up of the Congo-Sao Francisco Craton. The U-Pb age spectra of detrital zircons from metasediments of the Rio Doce Group(RDG) range from 900-650 Ma and define a maximum depositional age of ca. 650 Ma. Zircon trace element and whole rock data constrain an oceanic island arc as source for the deposition setting of the protoliths to the metasediments. Zircon ε_(Hf)(t) values from these rocks are positive between +1 and +15, supporting previous evidence of a Neoproterozoic extensional phase and oceanic crust formation in a precursor basin to the Aracuai Belt. Recrystallization of detrital zircon at ca. 630 Ma is compatible with a regional metamorphic event associated with terrane accretion to the Paleoproterozoic basement after transition from an extensional to a convergent regime. The juvenile nature, age spectra and trace element composition recorded in detrital zircons of metasediments from the Aracuai Belt correspond with zircons from metasedimentary rocks and oceanic crust remnants of other orogenic belts to its south. This suggests that rifting and oceanic crust formation of the entire orogenic system, the so-called Mantiqueira Province, was contemporaneous, most likely related to the opening of a large ocean. It further indicates that the cratonic blocks involved in the orogenic evolution of the Mantiqueira Province were spatially connected as early as 900 Ma.

关键词： Detrital zircon U-Pb geochronology Lu-Hf isotopes Trace elements Aracuaí Belt

Chemical-Abrasion U-Pb zircon geochronology reveals 150 Myr of partial melting events in the Archean crust of the São Francisco Craton

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Geoscience Frontiers 2022年第5期13卷 169-189页

作者： Lorena Martins cristiano lana Ariela Mazoz Tiago Novo Applied Isotope Research Group Departamento de GeologiaEscola de MinasUniversidade Federal de Ouro PretoMorro do CruzeiroOuro PretoMG35400-000Brazil Universidade Federal de Minas Gerais Programa de Pós-Graduação em GeologiaIGC-CPMTCCampus PampulhaAv.Antônio Carlos 6627Belo HorizonteMG31270-901Brazil

Field observations and CA-LA-ICP-MS U–Pb zircon ages and Hf isotope compositions obtained from migmatitic orthogneisses and granitoids from the Belo Horizonte Complex,southern São Francisco Craton,indicate a major period of partial melting and production of felsic rocks in the *** observations show that the complex is an important site for studying partial melting processes of Archean crystalline *** of the complex exposes fine-grained stromatic migmatites that are intruded by multiple leucogranitic veins and sheeted *** migmatites and leucogranite sheets are crosscut by several phases of granitoid batholiths and small granitic bodies;both of which are closely associated with the host banded *** abrasion followed by detailed cathodoluminescence imaging revealed a wide variety of zircon textures that are consistent with a long-lived period of partial melting and crustal *** of U-Pb and Hf isotopes disclose the complex as part of a much wider crustal segment,encompassing the entire southern part of the São Francisco *** of available U-Pb ages suggests that this crustal segment was consolidated sometime between 3000 Ma and 2900 Ma and that it experienced three main episodes of partial melting before stabilization at 2600 *** partial melting episodes took place between 2750 Ma and 2600 Ma as a result of tectonic accretion and peeling off the lithospheric mantle and lower *** process is likely responsible for the emplacement of voluminous potassic granitoids across the entire São Francisco *** believe that the partial melting of Meso-Archean crystalline crust and production of potassic granitoids are linked to a fundamental shift in the tectonics of the craton,which was also responsible for the widespread intrusion of large syenitic bodies in the northern part of the craton,and the construction of layered mafic–ultramafic intrusions to the south of the BHC.

关键词： Archean São Francisco Craton Crustal reworking U-Pb geochronology Lu-Hf isotopes

Metamorphism and exhumation of basement gneiss domes in the Quadrilátero Ferrífero:Two stage dome-and-keel evolution?

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Geoscience Frontiers 2019年第5期10卷 1765-1787页

作者： Kathryn Cutts cristiano lana Fernando Alkmim Federico Farina Hugo Moreira Viviane Coelho Applied Isotope Research Group Departamento de GeologiaEscola de MinasUniversidade Federal de Ouro PretoMorro do Cruzeiro35400-000Ouro PretoMGBrazil Department of Earth Sciences University of GenevaRue des Maraihers 131205GenevaSwitzerland School of Earth and Environmental Sciences University of PortsmouthBurnaby BuildingBurnaby RoadPortsmouthPO1 3QLUK

The presence of dome-and-keel provinces in Archean cratons has been connected with the initiation of plate tectonics on Earth as these features are most commonly observed in Archean *** Quadrilátero Ferrífero in Brazil has been identified as a Paleoproterozoic dome-and-keel province for more than three *** prevailing model suggests that it formed during the Rhyacian Transamazonian orogeny,making it unique among dome-and-keel ***,a lack of appropriate lithologies,datable minerals and the metamorphic overprint of later orogenesis has resulted in a cryptic metamorphic record for the formation of this dome-and-keel province.A clinopyroxene-bearing migmatite from the core of the Bacao dome has peak P-T conditions of 5-7 kbar and 700-750 ℃ and a published age of ca.2730 Ma based on U-Pb ages of zircon from leucosomes,suggesting that this age represents the migmatisation event.A fine-grained epidote-albite-titanite assemblage overprints the coarse-grained clinopyroxene and amphibole,giving P-T conditions of 8-9 kbar and 550℃ with an associated titanite age of ca.2050 Ma.A garnet-bearing amphibolite sample also from the core of the dome has peak P-T conditions of 7-8 kbar and 650-700℃,and texturally late titanite from this sample produces an age of ca.2060 *** additional samples were collected from the edges of the dome.A garnet-gedrite bearing felsic schist produces peak P-T conditions of 8-9 kbar and 650-700℃ on a clockwise P-T *** sample has a U-Pb zircon age of ca.2775 Ma,which could date metamorphism or be the age of its volcaniclastic *** unconstrained titanite from the sample gives an age of ca.2040 Ma.A garnet-bearing amphibolite that occurs as a boudin within the felsic schist gives both zircon and titanite ages of ca.2050 Ma and has peak P-T conditions of 5-6 kbar and 650-700 ℃ on a near isobaric P-T *** amphibolite dike,observed to cross-cut the felsic schist produces a zircon U-Pb age of ca.2760 Ma

关键词： Sao Francisco Craton Zircon U-Pb Titanite U-Pb Phase diagrams Dome-and-keel

Andean orogenic signature in the Quaternary sandy barriers of Southernmost Brazilian Passive Margin – Paradigm as a source area

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Geoscience Frontiers 2021年第4期12卷 61-70页

作者： Farid Chemale Junior Ernesto Luiz Correa Lavina Julierme Justin Carassai Tiago Jonatan Girelli cristiano lana Programa de Pós Graduação em Geologia Universidade do Vale do Rio dos Sinos93022-220São LeopoldoRSBrazil Departamento de Geologia Universidade Federal do Ouro Preto35400-000Morro do CruzeiroOuro PretoMGBrazil

Multiple source provenance of sediments and submarine fan formation are herein investigated based on Quaternary sandy barriers of the Brazilian Southernmost Coastal ***-ICP-MS dating on 1625 detrital zircons from marine and aeolian facies sands of four successive lagoon-barrier systems are *** characterization of Archean to Pleistocene zircons into a younger Andean(22±4 Ma to 1±1 Ma,48 from 1625),Mesozoic to Paleozoic,and Mesoproterozoic(479 from 1622)populations suggest that the main feeding of sediments to the coastal plain occurred through the La Plata River drainage *** significant contribution of sediments is transported from the mouth of La Plata River northward by longshore circulation(littoral drift).Minor contributions are also recognized as.a farther source associatedwith the Patagonia drainage and nearby source related to the Uruguay/Rio Grande do Sul Shield and the ParanáBasin,drained by the Camaquãand Jacuí*** latter one is recognized by the contribution fromNeoproterozoic to Early Paleozoic,and some Paleoproterozoic and Archean zircon *** definition of the sources of clastic sediments allows inferences about the origination of Rio Grande Fan where both the cold Falkland and the warm Brazil currents played a major role.

关键词： U–Pb zircon Coastal plain Andean provenance Source to sink process Rio Grande Fan Ocean Atlantic

Evolution of Siderian juvenile crust to Rhyacian high Ba-Sr magmatism in the Mineiro Belt, southern S?o Francisco Craton

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Geoscience Frontiers 2018年第4期9卷 977-995页

作者： Hugo Moreira Luís Seixas Craig Storey Mike Fowler Stephanie Lasalle Ross Stevenson cristiano lana School of Earth and Environmental Sciences University of Portsmouth Burnaby Building Bumaby Road Portsmouth POI 3QL UK Departamento de Geologia Escola de Minas Universidade Federal de Ouro Preto Ouro Preto MG 35400-000 Brazil GEOTOP Universite du Quebec a Montreal RO. Box 8888 Station Centre Ville Montreal Quebec H3C 3P8 Canada

Plutonic rocks from the Mineiro Belt, Brazil record a delayed onset of the transition from TTG to sanukitoid-type magmatism（high Ba-Sr）, starting during the Siderian magmatic lull when little juvenile magma was added to the continental crust. Rocks mostly belong to the calc-alkaline series, meta-to peraluminous and originally ＂Ⅰ-type＂,meaning that oxidized magmas were formed by partial melting of subducted material. The temporal distribution and apparent secular changes of the magmas are consistent with the onset of subduction-driven plate tectonics due to an increase of the subduction angle and opening of the mantle wedge. New isotopic analyses（Sm-Nd whole rock and Lu-Hf in zircon）corroborate the restricted juvenile nature of the Mineiro Belt and confirm the genetic link between the Lagoa Dourada Suite,a rare ca. 2350 Ma high-Al tonalite-trondhjemite magmatic event, and the sanukitoid-type ca. 2130 Ma Alto Maranhao Suite. U-Pb dating of zircon and titanite constrain the crystallisation history of plutonic bodies; coupled with major and trace element analyses of the host rocks, they distinguish evolutionary trends in the Mineiro Belt. Several plutons in the region have ages close to 2130 Ma but are distinguished by the lower concentration of compatible elements in the juvenile high Ba-Sr suite.

关键词： Sao Francisco Craton Magmatic lull TTG-Sanukitoid transition Zircon U-Pb-Hf Titanite U-Pb Whole rock Nd isotopes

A perspective on potassic and ultrapotassic rocks:Constraints on the Paleoproterozoic late to post-collisional event in the São Francisco paleocontinent

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Geoscience Frontiers 2022年第5期13卷 242-266页

作者： Samuel Moreira Bersan AndréDanderfer Craig Storey Henrique Bruno Hugo Moreira Francisco Abreu cristiano lana Leonardo Gonçalves Isabela Nahas Universidade Federal de Ouro Preto Departamento de GeologiaCampus Morro do CruzeiroOuro PretoMG CEP 35400-000Brazil University of Portsmouth School of the EnvironmentGeography and GeosciencesBurnaby BuildingBurnaby RoadPortsmouth PO13QLUK Tektos Research Group UERJ-Rio de Janeiro State UniversityBrazil Sustain Geologia Belo HorizonteBrazil

The late-to post-collisional stage in orogenic systems is characterized by the coeval existence of bimodal potassic to ultrapotassic magmatic activity related to partial melting of an enriched lithospheric mantle together with crustal derived *** this paper,we present new whole rock geochemical analyses combined with zircon and titanite U–Pb and zircon Hf isotopic data from potassic to ultrapotassic rocks from six plutons that occur within the Archean Itacambira-Monte Azul block(BIMA),to discuss their petrogenesis and the tectonic implications for the São Francisco *** new U–Pb ages range from ca.2.06 Ga to 1.98 Ga and reveal long-lasting potassic magmatism within the BIMA,which is within the late-to-post-collisional stage of the São Francisco paleocontinent *** ultrapotassic rocks are compatible with a fluid-related metasomatized mantle source enriched by previous subduction events,whereas the potassic rocks are bimodal and have a transitional shoshonitic to A-type *** rocks have a hybrid nature,possible related to the mixing between the mafic potassic/ultrapotassic rocks and high temperature crustal melts of the Archean continental *** results also show an increase of within-plate signature towards the younger potassic *** participation of an important Archean crustal component in the genesis of these rocks is highlighted by the common and occasionally abundant occurrence of Archean inherited *** Hf isotopic record shows that most of the zircon inheritance has dominantly subchondriticεHf(t)values,which fits a crustal reworking derivation from a similar Eo-to Paleoarchean precursor ***,the presence of juvenile 2.36 Ga zircon inheritance in an ultrapotassic sample reveal the existence of a hidden reservoir that is somewhat similar to the described for the Mineiro Belt in southern São Francisco paleocontinent.

关键词： Late-to post-collisional Potassic-ultrapotassic rocks U–Pb dating São Francisco paleocontinent Rhyacian-Orosirian orogenic system

Paleoproterozoic juvenile magmatism within the northeastern sector of the Sao Francisco paleocontinent:Insights from the shoshonitic high Ba-Sr Montezuma granitoids

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Geoscience Frontiers 2020年第5期11卷 1821-1840页

作者： Samuel Moreira Bersan Alice Fernanda de Oliveira Costa Andre Danderfer Francisco Roberio de Abreu cristiano lana Glaucia Queiroga Craig Storey Hugo Moreira Universidade Federal de Ouro Preto Programa de Pos-graduacaoDepartamento de GeologiaCampus Morro do CruzeiroOuro PretoMGCEP 35400-000Brazil Universidade Federal de Ouro Preto Departamento de GeologiaCampus Morro do CruzeiroOuro PretoMGCEP 35400-000Brazil Sustain Geologia Ltda Teresa M.Valadares 503/502Belo HorizonteMGCEP 30575-160Brazil University of Portsmouth School of Earth and Environmental SciencesBurnaby BuildingBurnaby RoadPortsmouthPO13QLUK

New,integrated petrographic,mineral chemistry,whole rock geochemical,zircon and titanite UPb geochronology,and zircon Hf isotopic data from the Montezuma granitoids,as well as new geochemical results for its host rocks represented by the Corrego Tingui Complex,provides new insights into the late-to post-collisional evolution of the northeastern Sao Francisco paleocontinent.U-Pb zircon dates from the Montezuma granitoids spread along the Concordia between ca.2.2 Ga to 1.8 Ga and comprise distinct *** I have crystallization ages between ca.2.15 Ga and 2.05 Ga and are interpreted as inherited *** II zircon dates vary from 2.04 Ga to1.9 Ga and corresponds to the crystallization of the Montezuma granitoids,which were constrained at ca.2.03 Ga by the titanite U-Pb *** age zoning is common within the ca.1.8 Ga Group III zircon ages,being related to fluid isotopic re-setting during the Espinhaco rifiting ***εHf(t)analysis show dominantly positive values for both Group I(-4 to+9)andⅡ(-3 to+8)zircons and TDM2 model ages of 2.7-2.1 Ga and 2.5-1.95 Ga,***,the Montezuma granitoids are weakly peraluminous to metaluminous magnesian granitoids,enriched in LILES and LREE,with high to moderate Mg#and depleted in some of the *** lithochemical signature,added to the juvenile signature of both inherited and crystallized zircons,allowed its classification as a shoshonitic high Ba-Sr granitoid related to a late-to post-collisional lithosphere delamination followed by asthenospheric *** this scenario,the partial melting of the lithospheric mantle interacted with the roots of an accreted juvenile intra-oceanic arc,being these hybrid magma interpreted as the source of the Montezuma *** Corrego Tingui Complex host rocks are akin to a syn-to late-collisional volcanic arc granitoids originated from the partial melting of ancient crustal *** results presented in this study have revealed the occurrence of j

关键词： Zircon U–Pb-Hf Titanite U–Pb High Ba–Sr Late-to post-collisional Sao Francisco paleocontinent

Unravelling the protracted U-Pb zircon geochronological record of high to ultrahigh temperature metamorphic rocks:Implications for provenance investigations

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Geoscience Frontiers 2023年第2期14卷 116-132页

作者： Mahyra Tedeschi Pedro Leonardo Rossi Vieira Matheus Kuchenbecker Bruno VRibeiro Vitor Barrote Humberto Reis Laura Stutenbecker cristiano lana Antonio Pedrosa-Soares Ivo Dussin Programa de Pós-graduação em Geologia da Universidade Federal de Minerais Centro de Pesquisas Manoel Teixeira da CostaInstitute of GeosciencesFederal University of Minas GeraisAv.Antônio Carlos6627Belo Horizonte 31270-901Brazil Institute of Geological Sciences University of Bern3012 BernSwitzerland Laboratório de Estudos Tectônicos Universidade Federal dos Vales do Jequitinhonha e MucuriRodovia MGT 367Km 583-Diamantina 39100-000Brazil School of Earth Atmosphere and EnvironmentMonash UniversityClaytonVictoria 3800Australia Timescales of Mineral Systems Group School of Earth and Planetary SciencesCurtin UniversityPerthWA 6845Australia Freie Universität Berlin Institut für Geologische WissenschaftenGeochemieMalteserstr.1074-10012249 BerlinGermany Departamento de Geologia-Escola de Minas Universidade Federal de Ouro Preto 35400-000Brazil Department of Materials and Earth Sciences Institute of Applied GeosciencesTU DarmstadtSchnittspahnstr.964287 DarmstadtGermany TEKTOS Geotectonic Research Group Geology InstituteRio de Janeiro State UniversitySão Francisco Xavier Street524/4030-AMaracanãRio de Janeiro 20550-900Brazil

The assessment of detrital zircon age records is a key method in basin analysis,but it is prone to several biases that may compromise accurate sedimentary provenance *** to ultrahigh temperature(HT-UHT)metamorphism(especially if T>850℃)is herein presented as a natural cause of bias in provenance studies based on U-Pb detrital zircon ages,since zircon from rocks submitted to these extreme and often prolonged conditions frequently yield protracted,apparently concordant,geochronological *** age spreading can result from disturbance of the primary U-Pb zircon system,likewise from(re)crystallization processes during multiple and/or prolonged metamorphic *** this contribution,available geochronological data on Archean,Neoproterozoic and Palaeozoic HT-UHT metamorphic rocks,acquired by different techniques(SIMS and LA-ICP-MS)and showing distinct compositions,are reassessed to demonstrate HT-UHT metamorphism may result in modes and age distributions of unclear geological *** a consequence,it may induce misinterpretations on UPb detrital zircon provenance analyses,particularly in sedimentary rocks metamorphosed under such extreme temperature *** evaluate the presence of HT-UHT metamorphism-related bias in the detrital zircon record,we suggest a workflow for data acquisition and interpretation,combining a multi-proxy approach with:(i)in situ U-Pb dating coupled with Hf analyses to retrieve the isotopic composition of the sources,and(ii)the integration of a petrochronological investigation to typify fingerprints of the HT-UHT metamorphic *** proposed workflow is validated in the investigation of one theoretical and one natural example allowing a better characterization of the sedimentary sources,maximum depositional ages,and the tectonic setting of the *** workflow allows to the appraisal of biases imposed by HT-UHT metamorphism and resulting disturbances in the U-Pb detrital zircon record,particularly for sedimentary

关键词： Detrital zircon Protracted zircon record Sedimentary basins UHT metamorphism Prolonged metamorphism Bias in detrital zircon

Record of Early Tonian mafic magmatism in the central Espinhaco(Brazil):New insights for break-up of the Neoproterozoic landmass ancestor of Sao Francisco-Congo paleocontinent

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Geoscience Frontiers 2020年第6期11卷 2323-2337页

作者： Helen F.Moreira AndréDanderfer Alice F.O.Costa Samuel M.Bersan cristiano C.lana Gláucia N.Queiroga Post Graduate Program of Department of Geology Mine SchoolFederal University of Ouro PretoBrazil Department of Geology Mine SchoolFederal University of Ouro PretoBrazil

Petrological characterization,U-Pb geochronology,Lu-Hf analyses and major and trace element data from mafic intrusions in the Central Espinhaco(central portion of the Brazilian shield)are used here to investigate the geological significance of the Early Neoproterozoic magmatism in the context of the Sao Francisco-Congo *** mafic bodies are represented by medium to coarse-grained metagabbros with plagioclase,amphibole and *** U-Pb isotopic data from two samples yielded weighted mean 206pb/238U ages of 895±3.4 Ma(MSWD=1.7)and 896±2.4 Ma(MSWD=0.64),regarded as the best estimates for the crystallization age of these mafic *** and trace element data(including REEs)show that the gabbros originated from a subalkaline tholeiitic magma,typical of intraplate *** rocks are slightly enriched in LREEs and LILEs and depleted in *** new isotope and geochemical data,along with regional knowledge,indicate that these metagabbros mark the beginning of an important Tonian-age extensional tectonic event of the landmass of which the Sao Francisco-Congo paleocontinent was part(Rodinia supercontinent or Central African block?).We furthermore suggest that these rocks belong to a prominent suite of Tonian-age mafic rocks that mark a diachronic breakup attempt of this landmass which may have occurred from south to north along the Espinhaco mountain range.

关键词： Mafic rocks Espinhaco basin Sao Francisco-Congo paleocontinent Tonian rifting U–Pb geochronology

Proto-Adamastor ocean crust(920 Ma)described in Brasiliano Orogen from coetaneous zircon and tourmaline

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Geoscience Frontiers 2019年第4期10卷 1623-1633页

作者： Léo A.Hartmann Mariana Werle Cassiana R.L. Michelin cristiano lana Gláucia N. Queiroga Marco P. Castro Karine R. Arena Instituto de Geociências Universidade Federal do Rio Grande do SulAvenida Bento Goncalves950091501-970Porto AlegreRio Grande do SulBrazil Departamento de Geologia Escola de MinasUniversidade Federal de Ouro PretoMorro do Cruzeiro35400-000Ouro PretoMinas GeraisBrazil

Proto-Adamastor ocean bathed Rodinia and successor continental fragments from 1.0-0.9 Ga up to0.75 Ga,and evolved into world Adamastor Ocean at 0.75-0.60 *** oceanic crust is poorly preserved on continents,only indirect evidence registered in Brasiliano *** report first evidence of ophiolite originated in *** use multi-technique U-Pb-Hf zircon andδ^11B tourmaline isotopic and elemental *** host tourmalinite is enclosed in metaserpentinite,both belonging to the Bossoroca *** is 920 Ma-old,εHf(920 Ma)=+12,HfTDM=1.0 Ga and has’oceanic’composition(e.g.,U/Yb<0.1).Tourmaline is dravite withδ^11B=+1.8‰(Tur 1),0‰(Tur 2),-8.5‰(Tur 3).These characteristics are a novel contribution to Rodinia and associated world ocean,because a fragment of proto-Adamastor oceanic crust and mantle evolved at the beginning of the Brasiliano Orogen.

关键词： Coeval zircon and tourmaline Bossoroca ophiolite Early Brasiliano Orogen Zircon U-Pb-Hf isotopes Zircon trace elements Tourmaline boron isotopes