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

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 

机构地区：[1]Programa de Pós-graduação em Geologia da Universidade Federal de Minerais,Centro de Pesquisas Manoel Teixeira da Costa,Institute of Geosciences,Federal University of Minas Gerais,Av.Antônio Carlos,6627,Belo Horizonte 31270-901,Brazil [2]Institute of Geological Sciences,University of Bern,3012 Bern,Switzerland [3]Laboratório de Estudos Tectônicos,Universidade Federal dos Vales do Jequitinhonha e Mucuri,Rodovia MGT 367,Km 583-Diamantina 39100-000,Brazil [4]School of Earth,Atmosphere and Environment,Monash University,Clayton,Victoria 3800,Australia [5]Timescales of Mineral Systems Group,School of Earth and Planetary Sciences,Curtin University,Perth,WA 6845,Australia [6]Freie Universität Berlin,Institut für Geologische Wissenschaften,Geochemie,Malteserstr.1074-100,12249 Berlin,Germany [7]Departamento de Geologia-Escola de Minas,Universidade Federal de Ouro Preto 35400-000,Brazil [8]Department of Materials and Earth Sciences,Institute of Applied Geosciences,TU Darmstadt,Schnittspahnstr.9,64287 Darmstadt,Germany [9]TEKTOS Geotectonic Research Group,Geology Institute,Rio de Janeiro State University,São Francisco Xavier Street,524/4030-A,Maracanã,Rio de Janeiro 20550-900,Brazil

出　　处：《Geoscience Frontiers》2023年第2期116-132,共17页地学前缘（英文版）

基　　金：supported by the Australian Research Council(FL160100168)。

摘　　要：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 investigations.High 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 records.Such age spreading can result from disturbance of the primary U-Pb zircon system,likewise from(re)crystallization processes during multiple and/or prolonged metamorphic events.In 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 meaning.As a consequence,it may induce misinterpretations on UPb detrital zircon provenance analyses,particularly in sedimentary rocks metamorphosed under such extreme temperature conditions.To 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 event.The 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 basin.Our 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 rocks that underwent HT-UHT metamorphism and,f

关 键 词：Detrital zircon Protracted zircon record Sedimentary basins UHT metamorphism Prolonged metamorphism Bias in detrital zircon 

分 类 号：P512.2[天文地球—地质学] P597.3