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Seafloor eruptions and evolution of hydrothermal fluid chemistry
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- By D. A. Butterfield, Joint Institute for the Study of Atmosphere and Ocean, University of Washington, Seattle, WA 98195, USA, I. R. Jonasson, Geological Survey of Canada, Ottawa, Ontario, Canada, G. J. Massoth, Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, WA 98115, USA, R. A. Feely, Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, WA 98115, USA, K. K. Roe, Joint Institute for the Study of Atmosphere and Ocean, University of Washington, Seattle, WA 98195, USA, R. E. Embley, Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Newport, OR 97365, USA, J. F. Holden, School of Oceanography, University of Washington, Seattle, WA 98195, USA, R. E. McDuff, School of Oceanography, University of Washington, Seattle, WA 98195, USA, M. D. Lilley, School of Oceanography, University of Washington, Seattle, WA 98195, USA, J. R. Delaney, School of Oceanography, University of Washington, Seattle, WA 98195, USA
- Edited by J. R. Cann, University of Leeds, H. Elderfield, University of Cambridge, A. S. Laughton, Southampton Oceanography Centre
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- Book:
- Mid-Ocean Ridges
- Published online:
- 04 August 2010
- Print publication:
- 22 July 1999, pp 153-170
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Summary
A major challenge confronting geochemists is to relate the chemistry of vented hydrothermal fluids to the local or regional tectonic and volcanic state of mid-ocean ridges. After more than 15 years of sampling submarine hydrothermal fluids, a complex picture of spatial and temporal variability in temperature and composition is emerging. Recent time-series observations and sampling of ridge segments with confirmed recent volcanic eruptions (CoAxial and North Cleft on the Juan de Fu caridge and 9–10° N on the East Pacific Rise) have created a first-order understanding of how hydrothermal systems respond to volcanic events on the seafloor. Phase separation and enhanced volatile fluxes are associated with volcanic eruptions, with vapour-dominated fluids predominating in the initial post-eruption period, followed in time by brine-dominated fluids, consistent with temporary storage of brine below the seafloor. Chemical data for CoAxial vents presented here are consistent with this evolution. Rapid changes in output and composition of hydrothermal fluids following volcanic events may have a profound effect on microbiological production, macrofaunal colonization, and hydrothermal heat and mass fluxes. Size and location of the heat source are critical in determining how fast heat is removed and whether subseafloor microbial production will flourish. Co Axial event plumes may be a direct result of dyking and eruption of lavas on the seafloor.
Lapita sites of the Bismarck Archipelago
- C. Gosden, J. Allen, W. Ambrose, D. Anson, J. Golson, R. Green, P. Kirch, I. Lilley, J. Specht, M. Spriggs
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The Lapita question
The prehistory of the western Pacific has, for the last 30 years, been dominated by the problem of the origins of the present Polynesian and Melanesian cultures (Terrell 1988). In 1961 Golson drew attention to the distribution of highly decorated Lapita pottery, now known to date from between 3500 BP and 2000 BP, which crossed the present-day division between Melanesia and Polynesia. Furthermore, sites with Lapita pottery represented the first evidence of occupation on Tonga and Samoa, the most westerly Polynesian islands from which it was thought that the rest of Polynesia was colonized. Lapita pottery came to be associated with a movement of people from Melanesia to Polynesia and was seen to represent the founding group ancestral to later Polynesian groups.