| Abstract: | Two types of massive sulphide were dredged from one of the six vent sites located in the axial valley of the southern Juan de Fuca ridge. Type A samples are angular slabs of dark grey Zn-rich sulphide with interlayers and a thin, partly-oxidized crust of Fe-sulphide. These layered sulphide aggregates appear to be fragments of a sulphide wall enclosing an active hydrothermal vent. The outer sulphide wall is composed of colloform Fe sulphide and Fe-poor sphalerite deposited under low-T conditions when sea-water and hydrothermal fluid mix above the discharge point. Inside the wall the intensifying hydrothermal sytem deposits a higher-T assemblage of granular Fe-rich sphalerite, wurtzite, pyrite and minor Cu-Fe sulphide. Type B sulphide samples are sub-rounded, spongy-textured fragments composed almost entirely of dendritic aggregates of pale Fe-poor colloform sphalerite and opaline silica. This type of sulphide is deposited in settings peripheral to sites of focused discharge and in open spaces by moderate- to low-T fluid discharging at a slow but variable rate; the fluid becomes increasingly oxidizing, resulting in late-stage deposits of hematite, baryte and sulphur.-L.di H. |
| Genre: | Article |
| ProdID: | 70013274 |
| Citation Author: | Koski, R. A.; Clague, D. A.; Oudin, E. |
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| Citation End Page: | 945 |
| Citation Issue: | 8 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geological Society of America Bulletin |
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| Citation Number Of Pages: | 16 |
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| Citation Search Results Text: | Mineralogy and chemistry of massive sulfide deposits from the Juan de Fuca Ridge.; 1984; Article; Journal; Geological Society of America Bulletin; Koski, R. A.; Clague, D. A.; Oudin, E. |
| Citation Start Page: | 930 |
| Citation Volume: | 95 |
| Citation Year: | 1984 |
| Type: | citation/reference |
| Text: | Mineralogy and chemistry of massive sulfide deposits from the Juan de Fuca Ridge.; 1984; Article; Journal; Geological Society of America Bulletin; Koski, R. A.; Clague, D. A.; Oudin, E. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Sun, 1 Jan 1984 00:00 -0600 |
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