Workshop Report - Ridge 2000 Program

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standard transect sampling and Lagrangian drifters. The development of Lagrangian drifters with in-situ chemical sensors would enhance our understanding of the long-term chemical evolution of hydrothermal emissions. . Laboratory, TheoreticaL and Numerical Modeling Laboratory, analytical and numerical simulation models provide valuable and instructive insight into ridge plume dynamics and variablity under controlled conditions. Such models will prove important to the interpretation of field observations and to the identification of key elements of plume dynamics. Refined plume models are needed to explain coalescing of multiple source vent fields and the effects of high frequency (tidal) cross-flow fluctuations on the spatial structure and temporal variability of plumes. Models will help predict the propagation, structural evolution and vorticity dynamics of episodic mesoscale plumes. Formed intermittently along mid-ocean ridges, these vent-like features are expected to display analogous behavior to warm and cold core eddies that proliferate within the upper ocean. Numerical simulation models are essential to our understanding of the general abyssal circulation and its interaction with mid-oceanic ridges. Such models are further needed to separate truly passive aspects of large scale plumes from active effects in which the plume induces modifications to the basin-scale background abyssal circulation. Models also should be applied to problems of particle-fluid transport within the heterogeneous media of vent fields. Modeling experiments are required for understanding the behavior of suspended particles and biological organisms within the circulation of oceanic plumes. This type of research is also essential for determining chemical process rates (such as metal and methane oxidation rates) within the plume environment and for providing estimates of the evolution and modification of advecting plumes. It is anticipated that many of the processes ubiquitous to hydrothermal vent sites can be accurately simulated through laboratory, analytical and numerical models. These models will help in the interpretation of observations within this convoluted oceanic regime and provide a basis for field experiments. Coordination with Other Investigations Plume studies are linked with other types of mid-ocean ridge investigations by commonalities in observational strategy and instrumentation. Improved cables and towed-sensors will facilitate simultaneous plume-mapping and geophysical surveys along ridge axes. The spacing and service requirements of seafloor instruments for both plume measurements and geophysical monitoring are comparable. Real-time detection of intense, episodic hydrothermal discharge may be helpful in locating foci of major crustal movements along ridge crests. Water column 57
studie!; that coordinate plume measurements and biological sampling will advance our understanding of the ecological role of the plume in distributing organic matter, bacteria, and plankton away from the vent field. On the ocean-basin scale, plume tracer studies complement other global programs committed to understanding oceanic circulation (WOCE) and chemical fluxes (GOFS) • 58
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The Mid-Oceanic Ridge A Dynamic G
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OCEAN STUDIES BOARD WALTER H. MUNK,
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PREFACE Recent discoveries of the w
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o Regional Scale: selected subsets
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1 INTRODUCTION The global mid-ocean
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papers were compiled, printed, and
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2 STATEMENT OF GOALS AND OBJECTIVES
Page 16 and 17: experience from land volcanic and m
Page 18 and 19: solid understanding of both the bio
Page 20 and 21: NEXT STEPS TOWARD A RIDGE INITIATIV
Page 22 and 23: 4 REPORTS OF THE WORKING GROUPS INT
Page 24 and 25: Critical Investigations The specifi
Page 26 and 27: Seismic refraction methods provide
Page 28 and 29: New Instrument and Laboratory Capab
Page 30 and 31: GROUP 2: GEOMETRY AND DYNAMICS OF M
Page 32 and 33: FORMATION OF OCEAN CRUST AT SPREADI
Page 34 and 35: 3. Regional Surveys. The third comp
Page 36 and 37: provide efficient and economically
Page 38 and 39: 3. Adaptation of tomographic invers
Page 40 and 41: Consequently, the sin;J1e most impo
Page 42 and 43: Thermal stresses have been suggeste
Page 44 and 45: electromagnetic fields must be meas
Page 46 and 47: capability should include at least
Page 48 and 49: In order to understand subseafloor
Page 50 and 51: fossil hydrothermal systems in ophi
Page 52 and 53: instrumented to record the environm
Page 54 and 55: GROUP 5: BIOLOGY OF HYDROTHERMAL SY
Page 56 and 57: There are several key questions abo
Page 58 and 59: Dispersal of Organisms What are the
Page 60 and 61: Strategy Biological studies will em
Page 62 and 63: GROUP 6: WATER COLUMN DYNAMICS AND
Page 64 and 65: On the ridge segment scale, detaile
Page 68 and 69: APPENDIX I The Mid-Oceanic Ridge: A
Page 70 and 71: Forsyth, Donald Department of Geolo
Page 72 and 73: Lonsdale. Peter Scripps Institution
Page 74 and 75: Reeve, Michael National Science Fou
Page 76: Tunnicliffe, Verena University of V
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Workshop Report - Ridge 2000 Program

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