摘要
SHRIMPU/Pb-zircondataandNdmeancrustalresidenceagesindicatethatthelmatacaComplexdevelopedfromanArchean(≥3.2Ga)continentalprotolithwhichhasundergoneconsiderableisotopicdisturbanceplusandjuvenileaccretionduringlate-Archean(-2.8Ga)times.Transamazoniangranulitesexperiencedpeakmetamorphicconditionsof750-800℃,6-8kbarwithassociatedtranspressivethrustingandtectonicimbrication.Geochronologyonzircon,pyroxeneandgarnetconstrainsthetimingofpeakmetamorphismat1.98-2.05Ga.DiffusionmodelingofFe-Mgexchangebetweenbiotiteinclusionsandhostgarnetyields(nearmetamorphicpeak)coolingratesof50-100℃/Ma,withpetrologicalcoolingratesbeinggenerallyconsistentwithcoolingratesdeterminedfromgeochronology.CombiningtheretrogradeP-Tpathwithcoolingratessuggeststhatafterthemetamorphicpeak,largeportionsofthelmatacaComplexwereexhumedfrom30to17kmatarateof7-2km/Ma.Afterthis,exhumationratesprogressivelydecreasedastherocksapproachedthesurface.Rapidoverallupliftlerosionhadceasedwhentherockspassedbelow600-550℃at2.01-1.96Gaago.Observedvariationsinmineralcoolingagesareinterpretedastoreflectepisodicdifferentialtectonicexhumationwithinmajorfaultsystems.Inferred(maximum)agesoffaultre-activationgenerallycoincidewithmajorcontinentalaccretioneventsintheAmazonianCratonandreflectlong-termthermalevolutionofthelmatacaterrane,asconditionedbyvariableresponsetocontinuedcontinentalconvergenceduringtheProterozoic.
出版日期
2004年01月11日（中国Betway体育网页登陆平台首次上网日期，不代表论文的发表时间）
