| Reference Type | Journal (article/letter/editorial) |
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| Title | Origin of Ba-rich sanidine megacrysts in a porphyry from Papua New Guinea |
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| Journal | Mineralogical Magazine | ISSN | 0026-461X |
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| Authors | Nixon, P. H. | Author |
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| Chapman, N. A. | Author |
| Smith, J. V. | Author |
| Year | 1980 (September) | Volume | 43 |
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| Issue | 331 |
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| Publisher | Mineralogical Society |
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| Download URL | https://rruff.info/doclib/MinMag/Volume_43/43-331-845.pdf+ |
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| DOI | doi:10.1180/minmag.1980.043.331.04Search in ResearchGate |
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| Generate Citation Formats |
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| Mindat Ref. ID | 3155 | Long-form Identifier | mindat:1:5:3155:8 |
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| GUID | 0 |
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| Full Reference | Nixon, P. H., Chapman, N. A., Smith, J. V. (1980) Origin of Ba-rich sanidine megacrysts in a porphyry from Papua New Guinea. Mineralogical Magazine, 43 (331) 845-850 doi:10.1180/minmag.1980.043.331.04 |
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| Plain Text | Nixon, P. H., Chapman, N. A., Smith, J. V. (1980) Origin of Ba-rich sanidine megacrysts in a porphyry from Papua New Guinea. Mineralogical Magazine, 43 (331) 845-850 doi:10.1180/minmag.1980.043.331.04 |
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| In | (1980, September) Mineralogical Magazine Vol. 43 (331) Mineralogical Society |
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| Abstract/Notes | SummaryA Miocene porphyry belonging to the sheshonite association contains 7 cm sanidine megacrysts in a groundmass of microphenocrysts of labradoritebytownite, augite, sporadic hastingsite, magnetite, sphene, K feldspar, apatite, Ca zeolite and calcite. The megacrysts (Or78–94) are enriched in BaO (≃ 2.0 wt%) and SrO relative to the groundmass. Although mineralogr and texture suggest that the megacrysts were suspended in a liquid, now represented by the groundmass, calculated liquid densities except for dry melts are less than those observed for the megacrysts and it is concluded that the original magma contained very little water. It possibly originated in a subduction zone with the main hycration taking place at shallow levels of intrusion during contact with groundwater. This produced zeolitization of the feldspars and may have played a part in the K enrichment at the margins of the sanidine megacrysts. |
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