{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,4]],"date-time":"2025-11-04T09:43:35Z","timestamp":1762249415238},"reference-count":50,"publisher":"Geological Society of London","issue":"4","license":[{"start":{"date-parts":[[2012,7,1]],"date-time":"2012-07-01T00:00:00Z","timestamp":1341100800000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-002"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JGS"],"published-print":{"date-parts":[[2012,7]]},"abstract":"<jats:p>\n            New geological mapping combined with U\u2013Pb ion microprobe zircon geochronology on the isolated but locally extensive exposures of crystalline basement inliers of eastern Graham Land has greatly improved our understanding of the region\u2019s early crustal evolution and has allowed a more thorough evaluation of Patagonia\u2013Antarctic Peninsula connections prior to Gondwana break-up. At Eden Glacier, diorite gneisses yield Early Ordovician protolith ages of 487 \u00b1 3 and 485 \u00b1 3 Ma and represent the oldest\n            <jats:italic>in situ<\/jats:italic>\n            rocks recorded on the Antarctic Peninsula, and indicate a significant spatial extension of Famatinian-age magmatism of Patagonia. Zircon overgrowths in the Early Ordovician protoliths and granitic leucosomes developed within them record two phases of Permian metamorphism at\n            <jats:italic>c<\/jats:italic>\n            . 275 and\n            <jats:italic>c<\/jats:italic>\n            . 257 Ma, coincident in part with diorite plutonism of the area at 272 \u00b1 2 Ma. At Adie Inlet, granitic leucosomes from paragneiss have been dated at 276 \u00b1 3 Ma, and these are in turn cut by 257 \u00b1 3 Ma xenolith-rich diorite gneiss. The diorite intruded during a second phase of deformation, which folded the paragneiss leucosomes into tight folds. This whole assembly is cut by intensely brecciated megacrystic granodiorite, which yielded a 259 \u00b1 3 Ma age. South of Cabinet Inlet a very different sequence of events is evident, with Triassic magmatism at\n            <jats:italic>c<\/jats:italic>\n            . 236 Ma extensive along the Joerg Peninsula. Migmatitic leucosomes are dated at\n            <jats:italic>c<\/jats:italic>\n            . 224 Ma and magmatism and deformation events apparently continued to\n            <jats:italic>c<\/jats:italic>\n            . 209 Ma at Cape Casey. Our data indicate that the Devonian and Carboniferous magmatism at Target Hill, considered to represent the \u2018classic\u2019 basement complex of the Antarctic Peninsula, is not representative regionally. The Target Hill crustal block contains a major break along Cabinet Inlet; to the north, Ordovician and Permian protoliths were variably migmatized during two episodes of Permian deformation and metamorphism, whereas to the south, Triassic protoliths and Triassic metamorphism are encountered.\n          <\/jats:p>\n          <jats:sec>\n            <jats:title>Supplementary material:<\/jats:title>\n            <jats:p>\n              U\u2013Pb isotopic data are available at\n              <jats:ext-link xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" ext-link-type=\"uri\" xlink:href=\"http:\/\/www.geolsoc.org.uk\/SUP18526\">http:\/\/www.geolsoc.org.uk\/SUP18526<\/jats:ext-link>\n              .\n            <\/jats:p>\n          <\/jats:sec>","DOI":"10.1144\/0016-76492011-142","type":"journal-article","created":{"date-parts":[[2012,7,11]],"date-time":"2012-07-11T16:02:12Z","timestamp":1342022532000},"page":"381-393","source":"Crossref","is-referenced-by-count":57,"title":["U\u2013Pb ion-microprobe zircon geochronology from the basement inliers of eastern Graham Land, Antarctic Peninsula"],"prefix":"10.1144","volume":"169","author":[{"given":"T. R.","family":"Riley","sequence":"first","affiliation":[{"name":"British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK"}]},{"given":"M. J.","family":"Flowerdew","sequence":"additional","affiliation":[{"name":"British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK"}]},{"given":"M. J.","family":"Whitehouse","sequence":"additional","affiliation":[{"name":"Swedish Museum of Natural History, Box 50007, SE-104 05 Stockholm, Sweden"}]}],"member":"1881","published-online":{"date-parts":[[2012,7,11]]},"reference":[{"key":"e_1_3_2_2_1","first-page":"442","article-title":"Lost terranes of Zealandia: possible development of Late Palaeozoic and early Mesozoic sedimentary basins at the southwest Pacific margin of Gondwanaland and their destination as terranes in southern South America","volume":"37","author":"Adams C.J.","year":"2011","unstructured":"Adams C.J. 2011. Lost terranes of Zealandia: possible development of Late Palaeozoic and early Mesozoic sedimentary basins at the southwest Pacific margin of Gondwanaland and their destination as terranes in southern South America. Andean Geology, 37, 442\u2013454.","journal-title":"Andean Geology"},{"key":"e_1_3_2_3_1","doi-asserted-by":"publisher","DOI":"10.1017\/S0016756807003469"},{"key":"e_1_3_2_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.epsl.2009.05.014"},{"key":"e_1_3_2_5_1","doi-asserted-by":"publisher","DOI":"10.1017\/S095410200999054X"},{"key":"e_1_3_2_6_1","doi-asserted-by":"publisher","DOI":"10.1017\/S001675681100080X"},{"key":"e_1_3_2_7_1","first-page":"EGU2009","article-title":"Sedimentary provenance of the Trinity Peninsula Group, Antarctic Peninsula: petrography, geochemistry and SHRIMP U\u2013Pb zircon age constraints","volume":"11","author":"Castillo P.","year":"2009","unstructured":"Castillo P., Lacassie J.P., Herv\u00e9 F., Fanning C.M. 2009. Sedimentary provenance of the Trinity Peninsula Group, Antarctic Peninsula: petrography, geochemistry and SHRIMP U\u2013Pb zircon age constraints. Geophysical Research Abstracts, 11, EGU2009\u20133084.","journal-title":"Geophysical Research Abstracts"},{"key":"e_1_3_2_8_1","first-page":"319","article-title":"New SHRIMP U\u2013Pb data from the Famatina complex: constraining Early\u2013Mid Ordovician Famatinian magmatism in the Sierras Pampeanas, Argentina","volume":"6","author":"Dahlquist J.A.","year":"2008","unstructured":"Dahlquist J.A., Pankhurst R.J. , et al. 2008. New SHRIMP U\u2013Pb data from the Famatina complex: constraining Early\u2013Mid Ordovician Famatinian magmatism in the Sierras Pampeanas, Argentina. Geologica Acta, 6, 319\u2013333.","journal-title":"Geologica Acta"},{"key":"e_1_3_2_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jsames.2011.03.007"},{"key":"e_1_3_2_10_1","doi-asserted-by":"publisher","DOI":"10.1029\/2005GL024636"},{"key":"e_1_3_2_11_1","doi-asserted-by":"publisher","DOI":"10.1017\/S0954102008001399"},{"key":"e_1_3_2_12_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00410-006-0091-6"},{"key":"e_1_3_2_13_1","doi-asserted-by":"publisher","DOI":"10.1086\/499570"},{"key":"e_1_3_2_14_1","doi-asserted-by":"publisher","DOI":"10.1130\/G20007.1"},{"key":"e_1_3_2_15_1","doi-asserted-by":"publisher","DOI":"10.1017\/S0954102096000582"},{"key":"e_1_3_2_16_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0895-9811(03)00022-1"},{"key":"e_1_3_2_17_1","doi-asserted-by":"publisher","DOI":"10.1017\/S0954102006000277"},{"key":"e_1_3_2_18_1","first-page":"215","volume-title":"Antarctica: Contributions to Global Earth Sciences","author":"Herv\u00e9 F.","year":"2006","unstructured":"Herv\u00e9 F., Miller H., Pimpirev C. 2006b. 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