Abstract
Fine grained gabbroic chilled margins and crosscutting dikes are associated in space and time with three ca. 1400 Ma anorthositic plutons in the Flowers River area, southeastern Nain igneous complex. Both the anorthositic and gabbroic rocks have distinctive compositions compared to rocks of similar age and lithology elsewhere in northcentral Labrador. The anorthositic rocks contain olivine and augite rather than orthopyroxene, and Fe-Ti oxides, apatite and orthoclase are unusually abundant. Cumulus plagioclase is abnormally enriched in incompatible elements. Most of the gabbroic rocks are uniform in composition, although the effects of contamination and fractionation are evident in some places. They define a transitional to alkalic ferrogabbro magma that is strongly enriched in K, P and incompatible trace elements. The chemical characteristics of the ferrogabbro magma imply derivation from enriched mantle or involvement of a significant crustal component. A parent-daughter relationship between the ferrogabbro magma and anorthositic rocks is suggested by their compositional similarities and the fact that the gabbroic chilled margins and plagioclase-rich pluton interiors appear to be completely gradational in composition and texture.
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Ashwal LD, Wooden JL, Emslie, RF (1986) Sr, Nd and Pb isotopes in Proterozoic intrusives astride the Grenville Front in Labrador: implications for crustal contamination and basement mapping. Geochim Cosmochim Acta 50:2571–2585
Baragar WRA (1981) Tectonic and regional relationships of the Seal Lake and Bruce River magmatic provinces. Geol Surv Can Bull 314, 72 p
Berg JH (1979) Physical constraints and tectonic setting of the Nain complex. Geol Assoc Can and Mineral Assoc Can Annual Meeting, Program with Abstracts, 4:39
Berg JH (1980) Snowflake troctolite in the Hettasch intrusion, Labrador: evidence for magma-mixing and supercooling in a plutonic environment. Contrib Mineral Petrol 72:339–351
Berg JH, Docka JA (1983) Geothermometry in the Kiglapait contact aureole, Labrador. Amer J Sci 283:414–434
Brooks C (1981) Supplement to the third report on the geochronology of Labrador. Newfoundland Department of Mines and Energy, unpublished report
Bryan WB, Finger LW, Chayes F (1969) Estimating proportions in petrographic mixing equations by least-squares approximation. Science 163:926–927
Carmichael ISE (1964) The petrology of Thingmuli, a Tertiary volcano in eastern Iceland. J Petrol 5:435–460
Chalokwu CI, Grant NK (1987) Reequilibration of olivine with trapped liquid in the Duluth complex, Minnesota. Geology 15:71–74
DePaolo DJ (1985) Isotopic studies of processes in mafic magma chambers: I. the Kiglapait intrusion, Labrador. J Petrol 26:925–951
Demaiffe D, Hertogen J (1981) Rare earth element geochemistry and strontium isotopic composition of a massif-type anorthositic-charnockitic body: the Hidra Massif (Rogaland, SW Norway). Geochim Cosmochim Acta 45:1545–1561
Duchesne JC, Demaiffe D (1978) Trace elements and anorthosite genesis. Earth Planet Sci Lett 38:249–272
Emslie RF (1978a) Elsonian magmatism in Labrador: age, characteristics and tectonic setting. Can J Earth Sci 15:438–453
Emslie RF (1978b) Anorthositic massifs, rapakivi granites, and late Proterozoic rifting of North America. Precamb Res 7:61–98
Emslie RF (1980) Geology and petrology of the Harp Lake complex, central Labrador: an example of Elsonian magmatism. Geol Surv Can Bull 293, 136 p
Emslie RF, Loveridge WD, Stevens RD (1984) The Mealy dikes, Labrador: petrology, age and tectonic significance. Can J Earth Sci 21:437–446
Fahrig WF, Loveridge WD (1981) Rb-Sr study of the Michael gabbro, Labrador. Geol Surv Can Paper 81-1C:99–103
Hill JD (1982) Geology of the Flowers River — Notakwanon River area, Labrador. Nfld Dept Mines Energy Rprt 82-6, 140 p
Hill JD, Thomas A (1983) Correlation of two Helikian peralkaline granite-volcanic centers in central Labrador. Can J Earth Sci 20:753–763
Irvine TN (1979) Rocks whose composition is determined by crystal accumulation and sorting. In: Yoder HS (ed) The evolution of the igneous rocks. Princeton Univ Press, pp 245–306
Kretz R (1982) Transfer and exchange equilibria in a portion of the pyroxene quadrilateral as deduced from natural and experimental data. Geochim Cosmochim Acta 46:411–421
Lindsley DH (1983) Pyroxene thermometry. Amer Mineral 68:477–493
MacDonald GA (1968) A contribution to the petrology of Tutuila, American Samoa. Geol Rund 57:821–837
MacDonald GA, Katsura T (1964) Chemical composition of Hawaiian lavas. J Petrol 5:82–133
McBirney AR (1975) Differentiation of the Skaergaard intrusion. Nature 253:691–694
McBirney AR, Williams H (1969) Geology and petrology of the Galapagos Islands. Geol Soc Amer Mem 118, 197 p
McLennan SM, Taylor SR (1980) Geochemical standards for sedimentary rocks: trace element data for USGS standards SCo-1, MAG-1 and SGR-1. Chem Geol 29:333–343
Meyers RE, Emslie RF (1977) The Harp dikes and their relationship to the Helikian geologic record in central Labrador. Can J Earth Sci 14:2683–2696
Morse SA (1981a) Kiglapait geochemistry III: potassium and rubidium. Geochim Cosmochim Acta 45:163–180
Morse SA (1981b) Kiglapait geochemistry IV: the major elements. Geochim Cosmochim Acta 45:461–479
Morse SA (1982a) A partisan review of Proterozoic anorthosites. Amer Mineral 67:1087–1100
Morse SA (1982b) Kiglapait geochemistry V: strontium. Geochim Cosmochim Acta 46:223–234
Morse SA, Nolan KM (1985) Kiglapait geochemistry VII: yttrium and the rare earth elements. Geochim Cosmochim Acta 49:1621–1644
Nathan HD, Van Kirk CK (1978) A model of magmatic crystallization. J Petrol 19:66–94
Nolan KM, Morse SA (1986) Marginal rocks resembling the estimated bulk composition of the Kiglapait intrusion. Geochim Cosmochim Acta 50:2381–2386
Philpotts JA, Schnetzler CC (1970) Phenocryst-matrix partition coefficients for K, Rb, Sr and Ba, with applications to anorthosite and basalt genesis. Geochim Cosmochim Acta 34:307–322
Ranson WA (1981) Anorthosites of diverse magma types in the Puttuaaluk Lake area, Nain complex, Labrador. Can J Earth Sci 18:26–41
Schilling JG, Winchester JW (1969) Rare earth contribution to the origin of Hawaiian lavas. Contrib Mineral Petrol 23:27–37
Schnetzler CC, Philpotts JA (1970) Partition coefficients of rareearth elements between igneous matrix material and rock-forming mineral phenocrysts — II. Geochim Cosmochim Acta 34:331–340
Spencer KJ, Lindsley DH (1981) A solution model for coexisting iron-titanium oxides. Am Mineral 66:1189–1201
Stout MZ, Nicholls J (1977) Mineralogy and petrology of Quaternary lavas from the Snake River plain, Idaho. Can J Earth Sci 14:2140–2156
Sun SS, Hanson GN (1975) Evolution of the mantle: geochemical evidence from alkali basalt. Geology 3:297–302
Thompson RN (1974) Primary basalts and magma genesis: I. Skye, north-west Scotland. Contrib Mineral Petrol 45:317–341
Tilley CE, Thompson RN (1979) Melting and crystallization relations of the Snake River basalts of southern Idaho, USA. Earth Planet Sci Lett 8:79–92
Wager LR, Brown GM (1967) Layered igneous rocks. Freeman and Co, San Francisco, 588 p
Wiebe RA (1980) Anorthositic magmas and the origin of Proterozoic anorthosite massifs. Nature 286:564–567
Wiebe RA (1985) Proterozoic basalt dikes in the Nain anorthosite complex, Labrador. Can J Earth Sci 22:1149–1157
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Geological Survey of Canada Contribution No. 54686.
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Hill, J.D. Alkalic to transitional ferrogabbro magma associated with paleohelikian anorthositic plutons in the Flowers River area, southeastern Nain igneous complex, Labrador. Contr. Mineral. and Petrol. 99, 113–125 (1988). https://doi.org/10.1007/BF00399371
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DOI: https://doi.org/10.1007/BF00399371