Late Maastrichtian–Paleocene chronostratigraphy from Seymour Island,James Ross Basin,Antarctic Peninsula:Eustatic controls on sedimentation  

作　　者：Manuel MONTES Elisabet BEAMUD Francisco NOZAL Sergio SANTILLANA 

机构地区：[1]Instituto Geológico y Minero de Espana(IGME),área de Geología,Geomorfología y Cartografía Geológica,Calera 1,28760-Tres Cantos,Madrid,Spain [2]Paleomagnetic Laboratory CCiTUB-Instituto de Ciencias de la Tierra'Jaume Almera’-CSIC,Sole i Sabaris,s/n,08028-Barcelona,Spain [3]Instituto Antártico Argentino,25 de Mayo 1143,San Martín,provincia de Buenos Aires,Argentina

出　　处：《Advances in Polar Science》2019年第3期303-327,共25页极地科学进展（英文版）

基　　金：supported by the Instituto Geológico y Minero de Espana (IGME) and Dirección General de Investigación (DGI) from Spain by the projects CTM2011-30241-C02-02 and CTM2014-60451-C2-2-P;the Geomodels Research Institute and the Grup de Recerca de Geodinàmica i Anàlisi de Conques (Grant no. 2017SGR596, supported by AGAUR)

摘　　要：The Paleocene(66–56 Ma)was a critical time interval for understanding the geological history in high palaeolatitudes after the end of Cretaceous event(recovery from mass extinction,palaeoclimate,global sea level changes,among others).The sedimentary succession from Seymour Island(Antarctic Peninsula)provides key reference material from this important phase of the early Cenozoic.A detailed age model is proposed for the López de Bertodano Formation(LBF),Sobral Formation(SF)and Cross Valley–Wiman Formation(CVWF)based on a new magnetostratigraphic section which integrates previous dinoflagellate cyst biostratigraphy,Iridium anomaly(K-Pg boundary),U-Pb zircon dating(airfall tuff)and strontium isotope values from macrofossils.The new composite magnetostratigraphic section,which includes the Cretaceous–Paleogene boundary,has been correlated to the GPTS from C29r up to C24r.The top of the LBF is confirmed as latest Maastrichtian to earliest Danian(~65.4 Ma)in age.The overlying SF is mostly Danian in age(~65.2–~63 Ma)and CVWF is Selandian–Thatenian(~61.3–56.9 Ma).LBF,SF and CVWF are unconformity-bounded units(alloformations)that record the geological evolution of the James Ross Basin during a period of relative decreasing tectonism but coeval with volcanic activity.Unconformity based internal units have been recognized,dividing each formation into allomembers(LBF:Molluscan and Cenozoic;SF:A,B and C;CVWF:Díaz,Ara?ado,Bahía Pingüino).The new age model allows correlation of base-level changes with eustatic sea-level fluctuations.The bases of the SF and CVWF are correlated with the 65.3 and 61.5 Ma sea level lowstands.The Paleocene(66–56 Ma)was a critical time interval for understanding the geological history in high palaeolatitudes after the end of Cretaceous event(recovery from mass extinction,palaeoclimate,global sea level changes,among others).The sedimentary succession from Seymour Island(Antarctic Peninsula)provides key reference material from this important phase of the early Cenozoic.A detailed age model is proposed for the López de Bertodano Formation(LBF),Sobral Formation(SF)and Cross Valley–Wiman Formation(CVWF)based on a new magnetostratigraphic section which integrates previous dinoflagellate cyst biostratigraphy,Iridium anomaly(K-Pg boundary),U-Pb zircon dating(airfall tuff)and strontium isotope values from macrofossils.The new composite magnetostratigraphic section,which includes the Cretaceous–Paleogene boundary,has been correlated to the GPTS from C29r up to C24r.The top of the LBF is confirmed as latest Maastrichtian to earliest Danian(～65.4 Ma)in age.The overlying SF is mostly Danian in age(～65.2–～63 Ma)and CVWF is Selandian–Thatenian(～61.3–56.9 Ma).LBF,SF and CVWF are unconformity-bounded units(alloformations)that record the geological evolution of the James Ross Basin during a period of relative decreasing tectonism but coeval with volcanic activity.Unconformity based internal units have been recognized,dividing each formation into allomembers(LBF:Molluscan and Cenozoic;SF:A,B and C;CVWF:Díaz,Ara?ado,Bahía Pingüino).The new age model allows correlation of base-level changes with eustatic sea-level fluctuations.The bases of the SF and CVWF are correlated with the 65.3 and 61.5 Ma sea level lowstands.

关 键 词：Paleocene MAGNETOSTRATIGRAPHY Antarctic Peninsula James Ross Basin Seymour Island 

分 类 号：P53[天文地球—古生物学与地层学]