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An Ar-40/Ar-39 geochronology on a mid-Eocene igneous event on the Barton and Weaver peninsulas: Implications for the dynamic setting of the Antarctic Peninsula

文献类型：期刊论文

作者Wang, Fei1; Zheng, Xiang-Shen1; Lee, Jong I. K.2; Choe, Won Hie2; Evans, Noreen3,4; Zhu, Ri-Xiang1
刊名GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
出版日期2009-12-08
卷号10
ISSN号1525-2027
关键词Ar-40/Ar-39 geochronology igneous event geodynamics delamination Antarctic
DOI10.1029/2009GC002874
文献子类Article
英文摘要The genesis of basaltic to andesitic lavas, mafic dikes, and granitoid plutons composing the subaerial cover on the Barton and Weaver peninsulas, Antarctica, is related to arc formation and subduction processes. Precise dating of these polar rocks using conventional Ar-40/Ar-39 techniques is compromised by the high degree of alteration (with loss on ignition as high as 8%). In order to minimize the alteration effects we have followed a sample preparation process that includes repeated acid leaching, acetone washing, and hand picking, followed by an overnight bake at 250 degrees C. After this procedure, groundmass samples can yield accurate age plateaus consisting of 70%-100% of the total 39 Ark released using high-resolution heating schedules. The different rock types studied on the Barton and Weaver peninsulas yielded almost coeval ages, suggesting a giant igneous event in the Weaver and Barton peninsulas at 44.5 Ma. A compilation of newly published ages indicate that this event took place throughout the whole South Shetland Islands, suggesting a dynamic incident occurred at this stage during the arc evolution history. We related this igneous event to a mantle delamination mechanism during Eocene times. The delamination process began at similar to 52 Ma, and the resultant upwelling of asthenosphere baffled the subduction of Phoenix plate, causing an abrupt decrease in convergence rate. Then multiple magmatic sources were triggered, resulting in a culminating igneous activity during 50-40 Ma with a peak at similar to 45 Ma along the archipelago. The delamination also caused the extension regime indicated by the dike swarm, plugs and sills all over the archipelago, and the uplift of Smith metamorphic complex and Livingston Island. Delamination process may have finished at some time during 40-30 Ma, leaving a weak igneous activity at that stage and thereafter. The convergence rate then recovered gradually, as indicated by the magnetic anomaly identifications. This model is supported by seismic observation of deep velocity anomalies beneath the Antarctic Peninsula.
WOS关键词SOUTH SHETLAND ISLANDS ; KING-GEORGE-ISLAND ; GONDWANA BREAK-UP ; K-AR ; PACIFIC MARGIN ; VOLCANIC-ROCKS ; SUBDUCTION HISTORY ; LIVINGSTON ISLAND ; DRAKE PASSAGE ; AGE
WOS研究方向Geochemistry & Geophysics
语种英语
出版者AMER GEOPHYSICAL UNION
WOS记录号WOS:000272712200001
资助机构KOPRI(PE09020 ; KOPRI(PE09020 ; Chinese Science Foundation(40221402 ; Chinese Science Foundation(40221402 ; PP09030) ; PP09030) ; 40873046 ; 40873046 ; 40672056 ; 40672056 ; 90714007) ; 90714007) ; KOPRI(PE09020 ; KOPRI(PE09020 ; Chinese Science Foundation(40221402 ; Chinese Science Foundation(40221402 ; PP09030) ; PP09030) ; 40873046 ; 40873046 ; 40672056 ; 40672056 ; 90714007) ; 90714007) ; KOPRI(PE09020 ; KOPRI(PE09020 ; Chinese Science Foundation(40221402 ; Chinese Science Foundation(40221402 ; PP09030) ; PP09030) ; 40873046 ; 40873046 ; 40672056 ; 40672056 ; 90714007) ; 90714007) ; KOPRI(PE09020 ; KOPRI(PE09020 ; Chinese Science Foundation(40221402 ; Chinese Science Foundation(40221402 ; PP09030) ; PP09030) ; 40873046 ; 40873046 ; 40672056 ; 40672056 ; 90714007) ; 90714007)
源URL[http://ir.iggcas.ac.cn/handle/132A11/71049]  
专题中国科学院地质与地球物理研究所
通讯作者Wang, Fei
作者单位1.Chinese Acad Sci, Inst Geol & Geophys, Paleomagnetism & Geochronol Lab, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China
2.KORDI, Korea Polar Res Inst, Inchon 406840, South Korea
3.CSIRO Explorat & Min, Kensington, WA 6151, Australia
4.Curtin Univ Technol, Dept Appl Geol, John de Laeter Ctr Mass Spectrometry, Perth, WA 6845, Australia
推荐引用方式
GB/T 7714		 Wang, Fei,Zheng, Xiang-Shen,Lee, Jong I. K.,et al. An Ar-40/Ar-39 geochronology on a mid-Eocene igneous event on the Barton and Weaver peninsulas: Implications for the dynamic setting of the Antarctic Peninsula[J]. GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,2009,10.
APA Wang, Fei,Zheng, Xiang-Shen,Lee, Jong I. K.,Choe, Won Hie,Evans, Noreen,&Zhu, Ri-Xiang.(2009).An Ar-40/Ar-39 geochronology on a mid-Eocene igneous event on the Barton and Weaver peninsulas: Implications for the dynamic setting of the Antarctic Peninsula.GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS,10.
MLA Wang, Fei,et al."An Ar-40/Ar-39 geochronology on a mid-Eocene igneous event on the Barton and Weaver peninsulas: Implications for the dynamic setting of the Antarctic Peninsula".GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS 10(2009).

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来源：地质与地球物理研究所

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