Mid-Ocean Ridges

Mid-Ocean Ridges: HYdrothermal Interactions Between the Lithosphere and Oceans......Page 3
Copyright......Page 4
CONTENTS......Page 5
PREFACE......Page 6
1. INTRODUCTION......Page 8
2.1. The East Pacific Rise at 9°-10°N......Page 10
2.3. Dike Emplacement: The "Quantum Events" of Fast-Spreading Ridges?......Page 11
2.4. Heat Released by ''Quantum" Diking Events......Page 13
2.6. Three Stages of Heat Release Associated with a DikingEvent......Page 14
3.1. The TAG Hydrothermal Field: An Unusually LargeHigh-Temperature Vent System......Page 17
3.2. The Rainbow Hydrothermal Field: An Even LargerHigh-Temperature Vent System......Page 18
3.3. Alternative Heat Sources at Slow-Spreading Ridges:Serpentinisation and Deeper Cooling......Page 19
4. SUMMARY AND CONCLUSIONS......Page 20
REFERENCES......Page 22
Geophysical Constraints Upon the Thermal Regime of the Ocean Crust......Page 26
2. KEY PROCESSES AND GLOBAL FLUXES......Page 27
3. THERMAL REGIME OF THE MANTLE BENEATHMID-OCEAN RIDGES......Page 32
4. MAGMA CHAMBERS AND THE PLUTONIC CRUST......Page 39
5. UPPER CRUST AND HYDROTHERMAL CIRCULATION......Page 48
6. HIGH LEVEL MAGMATIC SYSTEMS AND EVENTS......Page 58
7. AMAGMATIC HYDROTHERMAL SYSTEMS......Page 59
8. CONCLUSIONS......Page 61
REFERENCES......Page 62
1. INTRODUCTION......Page 70
2. RHEOLOGY OF THE OCEANIC LITHOSPHERE......Page 71
3. THE THERMAL STRUCTURE OF OCEANIC LITHOSPHERE......Page 76
4. FLEXURE AND THE ELASTIC PROPERTIES OF THE LITHOSPHERE......Page 77
5. THE THICKNESS OF THE SEISMOGENIC ZONE......Page 78
6. THE MEDIAN VALLEY AND THE AXIAL HIGH......Page 79
7. MORPHOLOGY AND CRUSTAL ARCHITECTURE OF RIDGE SEGMENTS......Page 82
8. LITHOLOGICAL STRUCTURE OF MID-OCEAN RIDGES......Page 84
9. FAULTING AT MID-OCEAN RIDGES......Page 85
10. SUMMARY OF OBSERVATIONS: RHEOLOGICAL STRUCTURE OF SLOW AND FAST-SPREADING RIDGES......Page 87
11. CONCLUSIONS......Page 88
REFERENCES......Page 91
1. INTRODUCTION......Page 101
2. WHY STUDYING THE THERMAL STRUCTURE OF OCEANIC CRUST?......Page 102
3. RIDGE THERMAL MODELS......Page 104
4. DISCUSSIONS......Page 107
REFERENCES......Page 112
1. INTRODUCTION......Page 117
2. LITHOLOGICAL STRUCTURE OF THE OCEAN CRUST AS A FUNCTION OF SPREADING RATE......Page 118
3. QUANTIFICATION OF SOURCES OF HEAT INMANTLE AND OCEAN CRUST......Page 122
4. USING BASALT COMPOSITION, SEISMIC CRUSTAL THICKNESS, AND REGIONAL AXIAL DEPTH TO CONSTRAIN THE MELT SUPPLY TO MID OCEAN RIDGES......Page 125
5. SUB-CRUSTAL MELT CRYSTALLISATION AT SLOW-SPREADING RIDGES......Page 131
6. CONSTRUCTION OF THE LOWER CRUST AT FAST-SPREADING RIDGES......Page 137
7. OCEANIC GABBROS AND OCEANIC MAGMA CHAMBERS AT FAST AND SLOW-SPREADING RIDGES......Page 140
9. EPISODICITY OF MAGMA INPUT......Page 141
10. TECTONIC ADVECTION OF HEAT AT SLOWSPREADING RIDGES......Page 142
11. CONCLUSIONS......Page 143
APPENDIX B. ESTIMATING MELT THICKNESS FROM MORB REE DATA......Page 145
APPENDIX C. MODELLING MANTLE MELTING,MELT THICKNESS, MELT SODIUM CONTENT, AND AXIAL DEPTH......Page 146
REFERENCES......Page 147
1. INTRODUCTION......Page 156
2. MODEL DESCRIPTION......Page 158
3. NUMERICAL RESULTS......Page 161
4. COMPARISON OF PREDICTED AND OBSERVED RIFT WIDTHS......Page 163
5. DISCUSSION......Page 164
REFERENCES......Page 168
Experimental Constraints on Thermal Cracking of Peridotite at Oceanic Spreading Centers......Page 171
2. MICROMECHANICAL MODELS......Page 172
3. EXPERIMENTAL TECHNIQUES......Page 178
4. RESULTS OF THERMAL CRACKING EXPERIMENTS......Page 180
5. DISCUSSION OF EXPERIMENTAL RESULTS......Page 183
6. CONCLUSIONS......Page 187
REFERENCES......Page 188
Submarine Lava Flow Emplacement at the East PacificRise 9° 50 'N: Implications for Uppermost Ocean Crust Stratigraphyand Hydrothermal Fluid Circulation......Page 190
1. INTRODUCTION......Page 191
2. THE EAST PACIFIC RISE 8°-11°N: BACKGROUND......Page 192
3. HAWAIIAN FISSURE ERUPTIONS AND MID-OCEAN RIDGE SUBMARINE VOLCANIC FEATURES......Page 195
5. EPR 9° 26-10°N VOLCANIC HISTORY AND SEAFLOOR MORPHOLOGY......Page 199
6. THE AXIAL SUMMIT TROUGH AND HYDROTHERMAL VENTS AT THE EPR 9° 46-51 'N......Page 200
7. DISCUSSION......Page 204
REFERENCES......Page 212
1. INTRODUCTION......Page 221
2. OBSERVATIONAL CONSTRAINTS AND MODEL PARAMETERS......Page 225
3. MATHEMATICAL MODELS OF RIDGE CRES THYDROTHERMAL CONVECTION-BASIC STATE......Page 227
4. EXTENSIONS OF THE SINGLE-PASS MODEL......Page 233
5. CONCLUSIONS AND SUGGESTIONS FOR FUTURE WORK......Page 238
REFERENCES......Page 239
1. INTRODUCTION......Page 247
2. THE GLOBAL VENT FIELD DISTRIBUTION......Page 249
3. "FAST" RIDGES......Page 253
4. "SLOW" RIDGES......Page 255
5. ULTRA SLOW RIDGES......Page 257
7. DISCUSSION......Page 260
8. CONCLUSIONS......Page 262
REFERENCES......Page 264
1. INTRODUCTION......Page 269
2. REVIEW OF pH CONTROLLING REACTIONS DURING HYDROTHERMAL ALTERATION INULTRAMAFIC SYSTEMS......Page 271
3. REDOX CONSTRAINTS IN HIGH-TEMPERATURE REACTION ZONES IN ULTRAMAFIC-HOSTED HYDROTHERMAL SYSTEMS......Page 273
4. CONTROLS ON DISSOLVED CHLORIDE AND TEMPERATURE......Page 276
5. CARBON REDUCTION REACTIONS A ND MINERAL CATALYSIS IN ULTRAMAFIC-HOSTED HYDROTHERMAL SYSTEMS......Page 279
6. CONCLUSIONS......Page 282
REFERENCES......Page 283
1. INTRODUCTION......Page 287
2. GEOLOGIC SETTING AND SAMPLE SITES......Page 288
4. RESULTS AND DISCUSSION......Page 292
5. TIME LINE......Page 299
REFERENCES......Page 304
Vigorous Venting and Biology at Pito Seamount, Easter Microplate......Page 307
1. INTRODUCTION......Page 308
2. DIVE OBSERVATIONS......Page 309
3. COMPOSITION OF SULFIDE DEPOSITS AND ROCK SAMPLES......Page 312
4. DISCUSSION......Page 315
REFERENCES......Page 318