Iron sulphide formation in an exhalative-sedimentary environment,Talasea, New Britain,P.N.G. |
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| Authors: | J Ferguson I B Lambert H E Jones |
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| Institution: | 1. Canberra City, Australia
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| Abstract: | Concentrations of iron sulphide minerals in sediments within and adjacent to a small intertidal thermal pool near Talasea township are forming and being modified under a wide range of exhalative-sedimentary conditions. A geochemical, mineralogical and bacteriological investigation of these iron sulphides has defined the major reactions leading to their formation and indicated aspects in which their mineralogies, textures and mechanisms of formation differ significantly from those of iron sulphides formed under “normal” sedimentary conditions. The main features of the thermal pool environment are: 1. the occurrence of relatively high iron sulphide concentrations; 2. the preservation, by the strongly anaerobic thermal spring waters, of hydrotroilite formed in the thermal pool sediments in the presence of excess sulphide; 3. the presence in the pool banks of major marcasite (which appears to replace its dimorph pyrite) formed as a result of the development of strongly acidic conditions; 4. the abundance in the pool banks of large euhedral crystals of pyrite and marcasite, and the scarcity of framboids; 5. the presence of sulphate-reducing bacteria in the thermal waters and sediments. |
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