Bimodal cyclical Archean basalts and rhyolites from the Michipicoten (Wawa) greenstone belt, Ontario: geochemical evidence for magma contributions from the asthenospheric mantle and ancient continental lithosphere near the southern margin of the Superior Province

Sage, R. P.; Lightfoot, Peter C.; Doherty, William O.S.

doi:10.1016/0301-9268(95)00020-8

Cited by 38 publications

(7 citation statements)

References 56 publications

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“…Independent of the alkali-alumina patterns, Thurston and Fryer (1983) noted that trace element data indicate that many of the felsic volcanic rocks of the Uchi-Confederation Lake area were derived by melting of trondhjemitic crust. Sage et al (1996a) suggested a similar derivation for the felsic volcanic rocks of the Wawa area. Finally, Galley (2003) noted that the felsic volcanic rocks hosting VMS deposits in the Archean Noranda and Sturgeon Lake areas, and Paleoproterozoic Snow Lake area are compositionally similar to the dominant tonalitetrondhjemite phases of synvolcanic intrusions of those areas.…”

Section: Discussionmentioning

confidence: 76%

Alkali-Alumina and MgO-Alumina Molar Ratios of Altered and Unaltered Rhyolites

Davies

Whitehead

2006

Exploration and Mining Geology

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Alkali-alumina and MgO-alumina plots are an effective instrument for displaying chemical and mineralogical compositions of altered and unaltered rhyolites and rhyodacites. They reveal that most supposedly unaltered rhyolites, apart from those of Cenozoic age, have undergone losses in Na 2 O and gains in K 2 O. The extreme loss of Na 2 O from highly altered rhyolites immediately adjacent to VMS deposits is strikingly illustrated by alkali-alumina plots. MgO/Al 2 O 3 vs. K 2 O/Al 2 O 3 diagrams display a strong negative correlation between MgO and K 2 O that results from the conversion of sericite to chlorite. A similar negative correlation between MgO and whole-rock δ 18 O is apparent on plots of these two parameters. Alkali-alumina plots underscore problems in selecting appropriate precursor compositions required for mass-balance calculations. Molar ratio plots are a viable alternative to such calculations.

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Section: Discussionmentioning

confidence: 76%

Alkali-Alumina and MgO-Alumina Molar Ratios of Altered and Unaltered Rhyolites

Davies

Whitehead

2006

Exploration and Mining Geology

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“…Major elements data and petrogenetic parameters are presented in Table 2 whereas Table 3 shows trace elements including rare earth elements. These gabbros show low AI values, ranging from 34.97-50.75 wt.%, indicating least affected by secondary alteration processes (Lafleche et al 1992;Sage et al 1996). The least alteration effects are also supported by their LOI values (0.54 to 1.74).…”

Section: Geochemistry and Petrogenesismentioning

confidence: 83%

Geochemical and biostratigraphic constraints on the genesis of mafic intrusive in the Buxa Dolomite (Neoproterozoic), Panging area of the Arunachal Lesser Himalaya, north east India

Gupta

Singh

2010

Journal of Nepal Geological Society

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Mafic intrusive within Neoproterozoic carbonates of Miri-Buxa Group in the Panging area of the Arunachal Lesser Himalaya, NE India has been reported for the first time. These mafic rocks have affinity to subalkaline-Mg-tholeiites and identified as low-Ti gabbro. Geochemically they are characterized by enrichment in LILE and LREE, depleted in HFSE with minor REE fractionated nature [(La/Yb)N = 2.70-3.29)] and positive Eu anomalies (Eu/Eu* = 1.00-1.30). These rocks have the influence of a within plate signature which were intruded in a continental rift tectonic environment. Petrogenetic modelings of [Mg]-[Fe] and REE suggest these mafic rocks probably derived from enriched mantle source similar to komatiitic composition at moderate to higher degree (35% - 50%) of partial melt. Based on the present reported microfossils viz. Rivularia haematites and Filamentus cyanobacteria in the chert lenses of the Buxa Dolomite from the Panging area, it is suggested that the gabbroic intrusion might have been taken place during Late Neoproterozoic which is probably close to the Precambrian–Cambrian boundary.

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“…The large volume of banded iron formations occurs at the Helen Iron Range, Wawa, Ontario in Canada (Goodwin et al, 1985;Sage et al, 1996). The age of the banded iron formations and surrounding rocks is approximately 2.7 billion years old (Corfu and Sage, 1993).…”

Section: Geological Evidence For Phosphorous Mobilization In the Archmentioning

confidence: 99%

Geochemical Cycles of Bio‐essential Elements on the Early Earth and Their Relationships to Origin of Life

2002

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Abstract:The bio-essential elements are demanded for the metabolic action of all living organisms. These elements are continuously supplied to biosphere through the elemental cycle on the surface Earth. The geochemical cycle of bio-essential elements was most likely different in the pre-biotic era (ca. 4.4 to 4.0 Ga) compared to the modern Earth. The difference was probably made by the absence of continents and biological mediation in the pre-biotic environments. Geochemical cycle models of bio-essential elements (P, B and Mo) on the pre-biotic Earth are proposed in this study, and these models are examined using available geochemical data.The input flux of phosphorous in pre-biotic oceans was probably dominated by submarine hydrothermal activities associated with carbonatized oceanic crusts. Such input flux by submarine hydrothermal activities is not known in the present-day oceans, and probably a unique flux in the pre-biotic oceans. Boron chemistry of pre-biotic oceans was also controlled by submarine hydrothermal input flux. The Mo exchange between the pre-biotic ocean and lithosphere may have restricted only at the submarine hydrothermal areas. These suggest that the submarine hydrothermal discharging areas were only locations to obtain bio-essential elements for the earliest life. This model is consistent with the previously proposed model for hydrothermal origin of life.

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Bimodal cyclical Archean basalts and rhyolites from the Michipicoten (Wawa) greenstone belt, Ontario: geochemical evidence for magma contributions from the asthenospheric mantle and ancient continental lithosphere near the southern margin of the Superior Province

Cited by 38 publications

References 56 publications

Alkali-Alumina and MgO-Alumina Molar Ratios of Altered and Unaltered Rhyolites

Alkali-Alumina and MgO-Alumina Molar Ratios of Altered and Unaltered Rhyolites

Geochemical and biostratigraphic constraints on the genesis of mafic intrusive in the Buxa Dolomite (Neoproterozoic), Panging area of the Arunachal Lesser Himalaya, north east India

Geochemical Cycles of Bio‐essential Elements on the Early Earth and Their Relationships to Origin of Life

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