Mineral chemistry of primary and secondary phases in basaltic rocks
Cobertura |
MEDIAN LATITUDE: 17.403600 * MEDIAN LONGITUDE: 154.709387 * SOUTH-BOUND LATITUDE: 12.096300 * WEST-BOUND LONGITUDE: 152.322900 * NORTH-BOUND LATITUDE: 21.923000 * EAST-BOUND LONGITUDE: 156.359800 * DATE/TIME START: 1989-11-26T02:45:00 * DATE/TIME END: 1990-01-16T07:15:00 |
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Data(s) |
11/04/1992
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Resumo |
Primary magmatic phases (spinel, olivine, plagioclase, clinopyroxene, amphibole, and biotite) and secondary phyllosilicates (smectite, chlorite-smectite, and celadonite) were analyzed by electron microprobe in alkalic and tholeiitic dolerites and basalts from Ocean Drilling Program Sites 800, 801, and 802. Aphyric alkalic dolerite sills (Hole 800A) and basalt flows (Holes 801B and 801C) share common mineralogical features: matrix feldspars are strongly zoned from labradorite cores to discrete sodic rims of alkali feldspar with a high Or component, which overlaps that of quench microlites in glassy mesostasis; little fractionated clinopyroxenes are Ti-rich diopsides and augites (with marked aegirine-augite rims at Site 801); rare, brown, Fe**3+-rich amphibole is winchite; and late biotites exhibit variable Ti contents. Alkalic rims to feldspars probably developed at the same time as quenched mesostasis feldspars and late-stage magmatic biotite, and represent the buildup of K-rich hydrous fluids during crystallization. Phenocryst phases in primitive mid-ocean ridge tholeiites from Hole 801C (Mg numbers about 70) have extreme compositions with chrome spinel (Cr/Cr + Al ratios about 0.2-0.4), Ni-rich olivine (Fo90), and highly calcic plagioclase (An90). Later glomerophyric clumps of plagioclase (An75-80) and clinopyroxene (diopside-augite) are strongly zoned and probably reflect rapidly changing melt conditions during upward transport, prior to seafloor quenching. In contrast, phenocryst phases (olivine, plagioclase, and clinopyroxene) in the Hole 802A tholeiites show limited variation and do not have such primitive compositions, reflecting the uniform and different chemical composition of all the bulk rocks. Replacive phyllosilicates in both alkalic and tholeiitic basalts include various colored smectites (Fe-, Mg-, and Al-saponites), chlorite-smectite and celadonite. Smectite compositions typically reflect the replaced host composition; glass is replaced by brown Fe-saponites (variable Fe/Mg ratios) and olivine by greenish Mg-saponites (or Al-rich chlorite-smectite). |
Formato |
application/zip, 15 datasets |
Identificador |
https://doi.pangaea.de/10.1594/PANGAEA.779095 doi:10.1594/PANGAEA.779095 |
Idioma(s) |
en |
Publicador |
PANGAEA |
Direitos |
CC-BY: Creative Commons Attribution 3.0 Unported Access constraints: unrestricted |
Fonte |
Supplement to: Rowbotham, G; Floyd, Peter A (1992): Mineral chemistry of primary and secondary phases in basaltic rocks, Leg 129. In: Larson, RL; Lancelot, Y; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 129, 305-434, doi:10.2973/odp.proc.sr.129.127.1992 |
Palavras-Chave | #129-800A; 129-801B; 129-801C; 129-802A; Al; Al2O3; Aluminium; Aluminium oxide; Amp; Amphibole; Biotite; Bt; Ca; Ca/(Ca+Na); CaCO3; Calcium; Calcium carbonate; Calcium number; Calcium oxide; Calculated based on oxygen number; CaO; Cel; Celadonite; Chromium; Chromium/(Aluminium+Iron+Chromium) ratio; Chromium(III) oxide; Chromium number; Cr; Cr/(Al+Fe+Cr); Cr/(Cr + Al); Cr/(Cr + Al + Fe3+); Cr2O3; DRILL; Drilling/drill rig; Electron microprobe; Elements, total; Event; Fe; Fe2+; Fe2O3; Fe3+; Fe3+/(Cr + Al + Fe3+); FeCO3; Feldspar; FeO; Fsp; Iron 2+; Iron 2+ and 3+; Iron 3+; Iron 3+ number; Iron carbonate, siderite; Iron oxide, Fe2O3; Iron oxide, FeO; Joides Resolution; K; K2O; Label; Leg129; Magnesium; Magnesium carbonate, magnesite; Magnesium number; Magnesium oxide; Manganese; Manganese carbonate, rhodochrosite; Manganese oxide; Mg; Mg/(Mg + Fe); Mg/(Mg + Fe2+); MgCO3; MgO; MgO/(MgO + FeO); Mn; MnO; Na; Na2O; Ni; Nickel; Nickel oxide; NiO; No; No O; North Pacific Ocean; Number; Number of oxygens; O; Ocean Drilling Program; ODP; ODP sample designation; Ol; Olivine; Oxygen; Position; Potassium; Potassium oxide; Pyrox; Pyroxene; Rds; Samp com; Sample code/label; Sample comment; Si; Silicon; Silicon dioxide; SiO2; Sme; Smectite; Sodium; Sodium oxide; Spinel; Spl; Sum; Ti; TiO2; Titanium; Titanium oxide; total; Zone |
Tipo |
Dataset |