Zusammenfassung
Wir folgern, daß die Formationsgruppe der Halbinsel Trinity in der antarktischen Halbinsel in ein Vorderbecken des Kompositentyps abgelagert wurde, das sich zwischen dem aus plutonischen und älteren gneißosen Urgesteinen bestehenden Bogengebirgsmassiv von Gondwana und einem Unterziehungskomplex befindet, der jetzt durch „Grünschiefer“ und „Blauschiefer“ und Albit-Epidot-Hornblende tragenden Gesteine von dem vorjurassischen metamorphen Komplex vertreten wird.
Die Formationsgruppe der Halbinsel Trinity ist hinsichtlich des Typs nochmals geprüft geworden und kann in Hope Bay-, View Point- und Legoupil-Formationen eingeteilt werden. Sedimentgesteine von allen Formationen sind von Turbiditfazies: Metalagerlaven werden zum ersten Mal durch diese Gesteine beschrieben.
Mehrphasige Schichtenfaltung ist in allen Formationen bemerkt geworden, und Regionalmetamorphose erreichte Prehnit- und Pumpellytfazies.
Analysen mit Mikrosonden der Relectpyroxenen in den Lagerlaven weisen darauf hin, daß das Stammagma wahrscheinlich Innenplattealkalibasalt war. Analysen der Schuttgranaten zeigen, daß sie sich von den metamorphen Granaten im Unterziehungskomplex auf Grund von Komposition unterscheiden, was darauf hinweist, daß diese dem Vorderbogenbecken keine bedeutende Belieferung von Material beschaffte.
Eine nahe Ähnlichkeit mit dem Terrane von Toriesse in Neuseeland wird bemerkt und wir schließen daraus, daß eine spätpalaeozoische - frühmesozoische Vorderbogenbeckenumgebung um den Rand des Pazifiks von Südamerika bis Neuseeland fast ununterbrochen erkannt werden kann.
Abstract
We infer that the Trinity Peninsula Group of the Antarctic Peninsula was deposited in a fore-arc basin(s) of composite type located between the Gondwanian arc massif (consisting of plutonic and older gneissose basement rocks) and a subduction complex, now represented by “greenschists”, “blueschists” and albite-epidote-hornblende-bearing rocks of the pre-Jurassic metamorphic complex.
The Trinity Peninsula Group has been re-examined in the type area and can be divided into the Hope Bay, View Point and Legoupil Formations. Sedimentary rocks of all formations are of turbidite facies; meta-pillow lavas are described for the first time from these rocks.
Multiphase folding has been observed in all formations and regional metamorphism reached prehnite-pumpellyite facies.
Microprobe analyses of relict pyroxenes in the pillow lavas indicate the parent magma was probably within-plate alkali basalt. Analyses of detrital garnets show that they are different in composition from metamorphic garnets in the subduction complex, indicating that the latter did not supply a significant amount of material to the fore-arc basin(s).
A close similarity with the Torlesse terrane in New Zealand is noted and we conclude that a late Palaeozoic-early Mesozoic fore-arc basin environment can be traced almost continuously around the Pacific margin from South America to New Zealand.
Résumé
Nous pensons que le Groupe de la Péninsule Trinity de la Péninsule Antarctique a été déposé dans un bassin de Farce externe de type composite situé entre le massif de l'arc Gondwanien (composé de roches plutoniques et de gneiss d'un socle plus ancien) et d'un complexe de subduction, représenté actuellement par des « schistesverts », «schistes-bleus» et des roches ă hornblende, albite et épidote du complexe métamorphique pré-Jurassique. Le Groupe de la Péninsule Trinity a été réexaminé dans la région-type; il peut être subdivisé en formations de Hope Bay, de View Point et de Legoupil. Les roches sédimentaires de toutes les formations sont du faciés turbiditique; pour la premiére fois des laves en coussins mêtamorphisées y sont décrites.
Un plissement multiphasé est observé dans toutes les formations, et le faciés préhnite pumpellyte marque le métamorphisme régional. Des analyses par microsonde de restes de pyroxene dans les laves en coussins démontrent que le magma parental etait probablement un basalte alcalin. Des analyses de grenats détritiques démontrent que les grenats sont d'une composition différente des grenats métamorphiques dans le complexe de subduction, indiquant que ces derniers n'ont fourni que peu de matériaux au bassin de l'arc externe.
La ressemblance est proche avec le terrain Torlessse de la Nouvelle Zélande et nous concluons qu'un environement de bassin d'arc externe (fin du Paléozoique à début du Mésozoique) peut être tracé presque sans interruption auteur de la marge Pacifique, entre l'Amérique du Sud et la Nouvelle-Zélande.
Краткое содержание
Авторы пришли к вывод у, что свиты полуостро ва Тринити антарктического полуострова отложен ы в бассейне передней дуги сложного типа, находи вшимся между дуговым массив ом Гондваны, составле нными плутонитами и древними гнейсовыми породами фундамента, и субдуцированным ком плексом, представлаенным сег одня „зеленым сланце м“, „голубыми сланцами“ и породами, вмещающим и альбит, эпидот и рого вую обманку из доюрского метаморфоного компл екса. Исследовали сви ты полуострова Тринити по их типам и подразде лили на формации: Hope Bay, View Point и Legoupil. Осадочные породы вс ех этих формаций проя вляют фаций мути; среднеподушечные да вы описаны здесь впер вые.
Многофазная складча точть слоев отмечена но всех отложениях, а региона льный метаморфизм достига ет фация Prehnit'a и Pumleppyit'a.
Данные анализа с помо щью микрозондов оста точных пироксенов в подушеч ных лавах указывают на то, что исходная магма, ве роятно, являлась внутриплитоным щело чным базальтом. Анали з обломков граната показал, что эти резко отличаю тся по своему составу от метаморфизированны х гранатов в субдуцированном ар еале; это говорит о том, что в бассейн передних дуг не поставлялось з начительных количес тв материала.
Отмечается сходство с областью Torlesse в Новой Зе дандии, и авторам кажется, что здесь в по зднем палеозое-ранне м мезозое простиралась непрер ывная дуга от Южной Америки до Новой Зеландии, кот орая обрамляла Тихий океан.
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References
Adie, R. J.: The petrology of Graham Land: III. Metamorphic rocks of the Trinity Peninsula Series. - Scient. Rep. Falkld. Isl. Depend. Surv. 20, 26 pp., London 1957.
Aitkenhead, N.: The geology of the Duse Bay-Larsen Inlet area, Northeast Graham Land. - Sci. Rep. Br. Antarct. Surv. 51, 62 pp. London 1975.
Berkland, J. O., Raymond, L. A., Kramer, J. C., Moores, E. M. &O'Day, M.: What is Franciscan? - Bull. Am. Ass. Petrol. Geol. 56, pp. 2295–2302, Chicago 1972.
Bishop, D. G.: Progressive metamorphism from prehnite-pumpellyite to greenschist facies in the Dansey Pass area, Otago, New Zealand. - Bull. geol. Soc. Am. 83, pp. 3177–3197. Rochester, New York 1972.
Boles, J. R. &Coombs, D. S.: Zeolite facies alteration of sandstone in the Southland Syncline, New Zealand. - Am. J. Sci. 277, pp. 982–1012, New Haven 1977.
Bradshaw, J. D.: Allochthonous Mesozoic fossil localities in mélange within the Torlesse rocks of North Canterbury. - J. R. Soc. N. Z. 3, pp. 161–167. Wellington 1973.
Campbell, J. D. &Warren, G.: Fossil localities of the Torlesse Group in the South Island. - Trans. R. Soc. N. Z. Geology, 3, pp. 99–137. Dunedin 1965.
Coombs, D. S.: The nature and alteration of some Triassic sediments from Southland. - Trans. R. Soc. N.Z. 82, pp. 65–109. Dunedin 1954.
Coombs, D. S., Landis, C. A., Norris, R. J., Sinton, J. M., Borns, D. J. &Craw, D.: The Dun Mountain ophiolite belt, New Zealand, its tectonic setting, constitution and origin with special reference to the southern portion. - Am. J. Sci. 276, pp. 561–603. New Haven 1976.
Coulbourn, W. T. &Moberly, R.: Structural evidence of the evolution of fore-arc basins off South America. - Can. J. Earth Sci. 14, pp. 102–116. Ottawa 1977.
Dalziel, I. W. D.: The pre-Jurassic history of the Scotia Arc: A review and progress report. - 3rd Symposium on Antarctic Geology and Geophysics Madison 1977, in press.
Dalziel, I. W. D. &Elliot, D. H.: Evolution of the Scotia Arc. - Nature 233, pp. 246–252. London 1971.
-: The Scotia arc and Antarctic margin. - In: The ocean basins and their margins: 1. The South Atlantic (F. G. Stehli & A. E. M. Nairn, eds.), pp. 171–246, New York 1973.
Dalziel, I. W. D., Elliot, D. H., Thomson, J. W., Thomson, M. R. A., Wells, N. A. &Zinsmeister, W. J.: Geologic studies in the South Orkney Islands, R/V Hero Cruise 77-1, January 1977. - Antarct. J. U. S. 12, pp. 98–101. Washington, D. C. 1977.
Dickinson, W. R. &Seely, D. R.: Structure and stratigraphy of fore-arc regions. - Bull. Am. Ass. Petrol. Geol. 63, pp. 2–31. Chicago 1979.
Elliot, D. H.: Geology of north-west Trinity Peninsula, Graham Land. - Bull. Br. Antarct. Surv. 7, pp. 1–24. London 1965.
—: Geology of the Nordenskjöld Coast and a comparison with northwest Trinity Peninsula, Graham Land. - Bull. Br. Antarct. Surv. 10, pp. 1–43. London 1966.
—: The geology of Joinville Island. - Bull. Br. Antarct. Surv. 12, pp. 23–40. London 1967 a.
—: The geochemistry of rocks from the Nordenskjöld Coast and north-west Trinity Peninsula. - Bull. Br. Antarct. Surv. 11, pp. 83–95. London 1967 b.
—: Tectonics of Antarctica: a review. - Am. J. Sci. 275 A, pp. 45–106. New Haven 1975.
Fleet, M.: Metamorphosed limestone in the Trinity Peninsula Series of Graham Land. - Bull. Br. Antarct, Surv. 7, pp. 73–76. London 1965.
-: The geology of the Oscar II Coast. - Sci. Rep. Br. Antarct. Surv. 59, 46 pp. London 1968.
Grikurov, G. E.: Tectonics of the Antarctandes. - In Antarctic Geology and Geophysics (R. J. Adie, ed.), pp. 163–167. Oslo 1972.
Grikurov, G. E. &Dibner, A. F.: New data on the Trinity Series (C1−2) in West Antarctica. - Dokl. Akad. Nauk SSSR. 179, pp. 410–112. Leningrad 1968.
Gledhill, A.,Rex, C. D. &Tanner, P. W. G.: Rb-Sr and K-Ar geochronology between Anvers Island and Marguerite Bay. - In 3rd Symposium on Antarctic Geology and Geophysics, Madison 1977. Madison, in press.
Halpern, M.: The geology of the General Bernado O'Higgins area, northwest Antarctic Peninsula. - In Geology and Paleontology of the Antarctic (J. B. Hadley, ed.), Antarct. Res. Ser. 6, pp. 177–209. Washington, D. C. 1965.
Jenkins, D. G. &Jenkins, T. B. H.: First diagnostic Carboniferous fossils from New Zealand. - Nature 233, pp. 117–118. London 1971.
LeBas, M. J.: The role of aluminium in igneous clinopyroxenes with relation to their parentage. - Am. J. Sci. 260, pp. 267–288. New Haven 1962.
Lllie, A. R. &Gunn, B. M.: Steeply plunging folds in the Sealy Range, Southern Alps. - N. Z. J. Geol. Geophys. 7, pp. 403–423. Wellington 1964.
Mansfield, C. F.: Upper Mesozoic subsea fan deposits in the southern Diablo Range, California: Record of the Sierra Nevada magmatic arc. - Bull. geol. Soc. Am. Part 1, 90, pp. 1925–1946. Rochester 1979.
Molnar, P., Atwater, T., Mammerickx, J. &Smith, S. M.: Magnetic anomalies, bathymetry and the tectonic evolution of the South Pacific since the late Cretaceous. - Geophys. J. R. astr. Soc.60, pp. 383–420. London 1975.
Nisbet, E. G. &Pearce, J. A.: Clinopyroxene composition in mafic lavas from different tectonic settings. - Contrib. Mineral. Petrol. 63, pp. 149–160. Berlin 1977.
Orlando, H. A.: A new Triassic flora from Livingston Island, South Shetland Islands. - Bull. Br. Antarct. Surv. 16, pp. 1–13. London 1968.
Reed, J. J.: Petrology of the lower Mesozoic rocks of the Wellington district. - Bull., geol. Surv. N. Z. 57, 60 pp. Wellington 1957.
Rex, D. C.: Geochronology in relation to the stratigraphy of the Antarctic Peninsula. - Bull. Br. Antarct. Surv. 43, pp. 49–58. London 1976.
Rvano, S. &Cortés, R.: Note on the presence of the lawsonite-sodic amphibole association on Smith Island, South Shetland Islands, Antarctica. - Earth Planet. Sci. Lett. 29, pp. 34–36. Amsterdam 1976.
Schopf, J. M.: Plant material from Miers Bluff Formation in the South Shetland Islands. - Rep. Inst. Polar Stud. Ohio State Univ. 45, Columbus 1973.
Shibata, T., Thompson, G. &Frey, F. A.: Tholeiitic and alkali basalts from the Mid-Atlantic Ridge at 43 °N. - Contrib. Mineral. Petrol. 70, pp. 127–141. Berlin 1979.
Smellie, J. L.: Aspects of the geology of the South Shetland Islands. - Unpub. Ph. D. thesis, University of Birmingham, UK. 198 pp. 1979.
Smellie, J. L. &Clarkson, P. D.: Evidence for pre-Jurassic subduction in Western Antarctica. - Nature 258, pp. 701–702. London 1975.
Suárez, M.: Plate-tectonic model for southern Antarctic Peninsula and its relation to southern Andes. - Geology 4, pp. 211–214. Boulder, Colorado 1976.
Thomson, M. R. A.: New palaeontological and lithological observations on the Legoupil Formation, North-west Antarctic Peninsula. - Bull. Br. Antarct. Surv. 41 & 42, pp. 169–185. London 1975.
Tyrrell, G. W.: Report on rocks from West Antarctica and the Scotia Arc. - ‘Discovery’ Rep. 23, pp. 37–102. Cambridge, UK. 1945.
de Wit, M. J., Dutch, S., Kligfield, R., Allen, R. &Stern, G.: Deformation, serpentinisation and emplacement of a dunite complex, Gibbs Island, South Shetland Islands: Possible fracture zone tectonics. - J. Geol. 85, pp. 745–762. Chicago 1977.
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Hyden, G., Tanner, P.W.G. Late Palaeozoic-early Mesozoic fore-arc basin Sedimentary rocks at the Pacific margin in Western Antarctica. Geol Rundsch 70, 529–541 (1981). https://doi.org/10.1007/BF01822133
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DOI: https://doi.org/10.1007/BF01822133