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The igneous geochemistry and tectonic setting of metabasites from the emo metamorphics, Papua New Guinea; A record of the evolution and destruction of a backarc basin

Die magmatische Geochemie und die tektonische Position von Metabasiten in den EmoMetamorphiten, Papua-Neuguinea; die Entwicklung und Zerstörung eines Backarc Beckens

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Summary

Metabasites from the Emo Metamorphics, occurring as thrust sheets beneath the Papuan ophiolite of Papua New Guinea, fall into four petrographic groups; Group 1 (garnetiferous blueschists), Group 2 (amphibolites), Group 3 (lawsonite blueschists) and Group 4 (greenschists). Most specimens shows a polymetamorphic history with textures grading from crudely foliated to mylonitic. Many contain primary igneous clinopyroxene, suggesting that metamorphism occurred under relatively low\(P_{H_2 O} \). This may explain the coherent magmatic geochemical signatures shown by many major elements normally mobilised during metamorphism. Geochemically the rocks are all tholeiitic in character and fall into three suites; Suite 1 are LREE depleted, resembling N-MORB with Zr/Nb values of > 40, Suite 2 are LREE enriched resembling E-MORB and having significantly lower Zr/Nb values of 8-16. Suite 3 includes ferrobasalts possibly comagmatic with Suite 2 but arbitrarily separated byP2O5 contents of > 0.5 and Zr contents of > 250 ppm. The three suites show significantly lower FeO* and higher AI2O3 than a Galapagos MORB comparative suite; these, and other trace element characteristics are normally associated with back-arc basin basalts. Two new39Ar-40Ar dates are presented, and a tectonic model developed integrating the geochemical and geochronological data with current models of the evolution of the New Guinea Orogen.

Zusammenfassung

Metabasite aus den Emo-Metamorphiten, die als Crustsheets unter dem Papua-Ophiolit von Papua-Neuguinea vorkommen, lassen sich auf petrographischer Basis in vier Gruppen unterteilen: Gruppe 1 (granatführende Blauschiefer) Gruppe 2 (Amphibolite), Gruppe 3 (Lawsonite-führende Blauschiefer) und Gruppe 4 (Grünschiefer). Die meisten Proben lassen eine polymetamorphe Entwicklung erkennen, mit Texturen, die vom grob gefältelten zum mylonitischen reichen. Viele enthalten primären magmatischen Klinopyroxen, was darauf hinweist, daß die Metamorphose bei relativniedrigen\(P_{H_2 O} \) stattgefunden hat. Das dürfte auch die eindeutig magmatischen geochemischen Signaturen erklären, die viele Hauptelemente, die sonst während der Metamorphose mobilisiert werden erkennen lassen. Geochemisch sind alle Gesteine als tholeütisch zu bezeichnen und lassen sich in drei Suiten unterteilen: Suite I sind LREE verarmt, und ähneln E-MORB mit signifikant niedrigen Zr-Nb Werten von 8-16. Suite 111 umfaßt Ferrobasalte, die möglicherweise mit Suite 11 komagmatisch sind aber durch P2O5 Gehalte von > 0.5 und Zr-Gehalte von > 250 ppm sich von den ersteren unterscheidet. Die drei Suiten zeigen signifikant niedrigere FeO und höhere Al2O3 als eine MORB vergleichbare Suite von Galapagos. Diese und andere Spurenelement-Verteilungsmuster sind üblicherweise mit Backarc-Becken Basalten assoziiert. Zwei neue39Ar/40Ar Altersbestimmungen werden vorgelegt und ein tektonisches Modell wird entwickelt, das die geochemischen und die geochronologischen Daten mit gängigen Modellen zur Entwicklung des Orogens von Neuguinea integriert.

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References

  • Clague DA, Frey FA, Thompson G, Rindge S (1981) Minor and trace element geochemistry of volcanic rocks dredged from the Galapagos Spreading Centre: role of crystal fractionation and mantle heterogeneity. J Geophys Res 86: 9469–9482

    Google Scholar 

  • Crawford AJ, Keays RR (1987) Petrogenesis of Victorian Cambrian tholeiites and implications for associated boninites.J Petrol 28: 1075–1109

    Google Scholar 

  • Danyushevsky LV, Falloon TJ, Sobolev AV, Crawford AJ, Carroll M, Price RC (1993) The H2O content of basalt glasses from Southwest Pacific back-arc basins. Earth Planet Sci Lett 117: 347–362

    Google Scholar 

  • Davies GR, Lloyd FE (1988) Pb-Sr-Nd isotope and trace element data bearing on the origin of the potassic subcontinental lithosphere beneath south west Uganda. In:O'Reilly SY(ed) Kimberlites and related rocks, vol 2. Geol Soc Aust Spec Pub 14: 784–794 (Blackwell Scientific, Australia, pp 1271)

    Google Scholar 

  • Davies HL (1971) Peridotite-gabbro-basalt complex in eastern Papua: an overthrust plate of oceanic mantle and crust. Bur Min Res Geol Geophys Austr Bull 128: 48pp

  • Davies HL (1980) Crustal structure and emplacement of ophiolite in southeastern Papua New Guinea. In:Allegre C, Aubouin J (compilers) Orogenic mafic ultramafic association. Centre National de la Recherche Scientifique, Paris. Colloques Internationaux 272: 17–33

    Google Scholar 

  • Davies HI, Smith IE (1971) Geology of Eastern Papua. Geol Soc Am Bull 82: 3299–3312

    Google Scholar 

  • Dow DB (1977) Geological synthesis of Papua New Guinea. Bur Min Res Geol Geophys Austr Bull 201: 41pp

  • Eissen J-P, Lefevre C, Maillet P, Morvan G, Nohara M (1991) Petrology and geochemistry of the central North Fiji Basin spreading centre (SW Pacific) between 16°S and 22°S. Marine Geol 98: 201–239

    Google Scholar 

  • Eissen J-P, Nohara M, Cotten C, Hirose K (1994) North Fiji Basin basalts and their magma sources, part I. Incompatible element constraints. Marine Geol 116: 153–178

    Google Scholar 

  • Finlayson DM, Drummond BJ, Collins CDN, Connelly JB (1977) Crustal structures in the region of the Papuan Ultramafic Belt. Phys Earth Planet Int 14: 13–29

    Google Scholar 

  • Fisk MR, Bence AE, Schilling J-G (1982) Major element chemistry of Galapagos Rift Zone magmas and their phenocrysts. Earth Planet Sci Lett 61: 171–189

    Google Scholar 

  • Fornari DJ, Perfit MR, Malahoff A, Embley R (1983) Geochemical studies of abyssal lavas recovered by DSRV Alvin from eastern Galapagos Rift, Inca Transform, and Ecuador Rift. l. Major element variations in natural glasses and spatial distribution of lavas. J Geophys Res 88: 10519–10529

    Google Scholar 

  • Glaessner MF (1949) Mesozoic fossils from the Snake River, central New Guinea. Mem Queensland Mus 12(4):165–181

    Google Scholar 

  • Hamilton W (1979) Tectonics of the Indonesian Region. US Geol Surv Prof Paper 1078: 236–27

    Google Scholar 

  • Hill KC, Grey A, Foster D, Barrett R (1993) An alternative model for the Oligo-Miocene evolution of northern PNG and the Sepik-Ramu basins. In:Carman GJ, Carman Z (eds) Petroleum exploration in Papua New Guinea. Proc Second PNG Petrol Conv, Port Moresby, pp 241–259

    Google Scholar 

  • Hobson DM (1986) A thin skinned model for the Papuan thrust belt and some implications for hydrocarbon exploration. J Aust Petrol Expl Assoc 26: 214–224

    Google Scholar 

  • Le Roex AP (1987) Source regions of mid-ocean ridge basalts: evidence for enrichment processes. In:Menzies MA, Hawkesworth CJ (eds) Mantle metasomatism. Academic Press, London, pp 389–422

    Google Scholar 

  • Michard A., Goffe B, Saddiqi O, Oberhansli R, Wendt A (1993) Late Cretaceous exhumation of the Oman blueschists and eclogites: a two-stage extensional mechanism. Terra Nova 6: 404–413

    Google Scholar 

  • Miyashiro A (1975) Volcanic rock series and tectonic setting. Ann Rev Earth Planet Sci 3: 251–269

    Google Scholar 

  • Nohara M, Hirose K, Eissen J-P, Urabe T, Joshima M (1994) The North Fiji Basin basalts and their magma sources, part II. Sr-Nd isotopic and trace element constraints. Marine Geol 116:179–195

    Google Scholar 

  • Pearce JA (1980) Geochemical evidence for the genesis and eruptive setting of lavas from Tethyan ophiolites. In:Panayiotou A (ed) Ophiolites. Proc Int Ophiolite Symp Cyprus 1979; Rep Cyprus Geol Surv Depart, Nicosia, pp 263–272

    Google Scholar 

  • Perfit MR, Fornari DJ (1983) Geochemical studies of abyssal lavas recovered by DSRV Alvin from Eastern Galapagos Rift, Inca Transform, and Ecuador Rift. 2. Phase chemistry and crystallisation history. J Geophys Res 88: 10530–10550

    Google Scholar 

  • Pieters PE (1978) Port Moresby-Kalo-Aroa Papua New Guinea 1: 250,000 Geological Series. Bur Min Resour Geol Geophys Austr Explanatory Notes SC/55-67 11 (unpublished)

  • Pigram CJ, Panggabean H (1984) Rifting of the Northern Margin of the Australian Continent and the origin of some microcontinents in Eastern Indonesia. Tectonophys 107: 331–353

    Google Scholar 

  • Pigram CJ, Davies HL (1987) Terranes and the accretion history of the New Guinea orogen. BMR J Aust Geol Geophys 10: 193–211

    Google Scholar 

  • Pigram CJ, Symonds PA (1991) A review of the timing of the major tectonic events in the New Guinea orogen. J Southeast Asian Earth Sci 6: 307–318

    Google Scholar 

  • Robinson P, Higgins NC, Jenner GA (1986) Determination of rare earth elements, yttrium and scandium in rocks by an ion exchange-X-ray fluorescence technique. Chem Geol 55: 121–137

    Google Scholar 

  • Rogerson R, Haig DW, Nion STS (1981) Geology of Port Moresby. Geol Surv Papua New Guinea, Report 81-16, 56pp

  • Rogerson RJ, Hilyard DB (1990) Scrapland: a suspect composite terrane in Papua New Guinea. In:Carman GJ, Carman Z (eds) Petroleum exploration in Papua New Guinea. Proc First PNG Petrol Conv, Port Moresby, pp 271–282

    Google Scholar 

  • Sinton JM, Fryer P (1987) Mariana trough lavas from 18°N: implications for the origin of back are basin basalts. J Geophys Res 92: 782–802

    Google Scholar 

  • Sinton JM, Detrick RS (1992) Mid-ocean ridge magma chambers. J Geophys Res 97: 197–216

    Google Scholar 

  • Smith RI (1990) Tertiary plate tectonic setting and evolution of Papua New Guinea. In:Carman GJ, Carman Z (eds) Petroleum exploration in Papua New Guinea. Proc First PNG Petrol Conv, Port Moresby, pp 229–244

    Google Scholar 

  • Smith IE, Davies HL (1976) Geology of the southeast Papuan mainland. Bur Min Res Aust Bull 165: 86pp

  • Struckmeyer HIM, Yeung M, Pigram CJ (1993) Mesozoic to Cainozoic plate tectonic palaeogeographic evolution of the New Guinea region. In:Carman GJ, Carman Z (eds) Petroleum exploration in Papua New Guinea. Proc Second PNG Petrol Conv, Port Moresby, pp 261–290

    Google Scholar 

  • Sun S-s, McDonough WF (1989) Chemical and isotopic systematics of ocean basalts: implications for mantle composition and processes. In:Saunders AD, Norry MJ (eds) Magmatism in the ocean basins. Geol Soc Lond, Spec Pub 42: 313–345

    Google Scholar 

  • Taylor L, Falvey DA (1977) Queensland Plateau and Coral Sea Basin: stratigraphy, structure and tectonics. J Aust Petrol Explor Assoc 17: 13–29

    Google Scholar 

  • Wai KM, Abbott MJ, Grady AE (1994) The Sadowa Igneous Complex, eastern Papua: ophiolite or not. Mineral Mag 58: 949–950

    Google Scholar 

  • Walsh JN, Buckley F, Baker J (1981) The simultaneous determination of the rare earth elements in rocks using inductively coupled plasma source spectrometry. Chem Geol 33: 141–153

    Google Scholar 

  • Weissel JK, Watts AB (1979) Tectonic evolution of the Coral Sea Basin. J Geophys Res 84: 4572–4582

    Google Scholar 

  • Wilson AD (1955) Method for the determination of ferrous iron in rocks and minerals. Bull Geol Surv Great Britain 9: 56–58

    Google Scholar 

  • Worthing MA (1987) Deerite from Papua New Guinea. Mineral Mag 51: 689–693

    Google Scholar 

  • Worthing MA (1988) Petrology and tectonic setting of blueschist facies matabasites from the Emo Metamorphics of Papua New Guinea. Aust J Earth Sci 35: 159–168

    Google Scholar 

  • Worthing MA, Bennett MA (1988) Geochemistry, mineralogy and tectonic setting of deeritebearing meta-ironstones from the Emo Metamorphics of Papua New Guinea. Aust J Earth Sci 35: 29–38

    Google Scholar 

  • Worthing MA, Midobatu C, Nixon PH (1992) Structural setting, petrology and emplacement of serpentinites in the Koki Fault Zone, Port Moresby, Papua New Guinea. J Southeast Asian Earth Sci 7: 147–158

    Google Scholar 

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Worthing, M.A., Crawford, A.J. The igneous geochemistry and tectonic setting of metabasites from the emo metamorphics, Papua New Guinea; A record of the evolution and destruction of a backarc basin. Mineralogy and Petrology 58, 79–100 (1996). https://doi.org/10.1007/BF01165765

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