Magmatism at mid-ocean ridges: Constraints from volcanological and geochemical investigations

Geophysical Monograph Series

Volumn 106, Issue , 1998, Pages 59-115

  Perfit, Michael R ^a   Chadwick, William W ^b  

^a UNIVERSITY OF FLORIDA   (United States)

^b OREGON STATE UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 84995286272     PISSN: 00658448     EISSN: 23288779     Source Type: Book Series    
DOI: 10.1029/GM106p0059     Document Type: Chapter

References (268)

1. AbdaUah, A., V. Courtillot, M. Kasser, A. Y. Le Dain, J. C. Lepine, B. Robineau, J. C. Ruegg, P. Tapponnier, and A. Tarantola, Relevance of Afar seismicity and volcanism to the mechanics of accreting plate boundaries, Nature, 282, 17-23, 1979.
2. Allan, J. F., R. Batiza, M. R. Perfit, D. J. Fomari, and R. O. Sock, Pebology of lavas from the Lamont seamount chain and adjacent East Pacific Rise, J. Petrol., 30, 1245-1298, 1989.
3. Auzende, J. M., et al., Recent tectonic, magmatic, and hydrothennal activity on the East Pacific Rise between 17°S and 19°S: Submersible observations, J. Geophys. Ret., 101, 17995-18010, 1996.
4. Auzende, J. M., and J. Sinton, NAUDUR explorers discover recent volcanic activity along the East Pacific Rise, Eos Trans. Am. Geophys. Union, 75, 601 and 604-605, 1994.
5. Baker, E. T., and S. R. Hammond, Hydrothermal venting and the apparent magmatic budget of the Juan de Fuca Ridge, J. Geophys. Res., 97, 3443-3456, 1992.
6. Baker, E. T., J. W. Lavelle, R. A. Feely, G. J. Massoth, S. L. Walker, and J. E. Lupton, Episodic venting of hydrothermal fluids from the Juan de Fuca Ridge, J. Geophys. Res., 94, 9237-9250, 1989.
7. Baker, E. T., G. J. Massoth, and R. A. Feely, Cataclysmic hydrothermal venting on the Juan de Fuca Ridge, Nature, 329, 149-151, 1987.
8. Baker, E. T., G. J. Massoth, R. A. Feely, R. W. Embley, R. E. Thomson, and B. J. Burd, Hydrothennal event plumes from the CoAxial seafloor eruption site, Juan de Fuca Ridge, Geophys. Res. Lett., 22, 147-150, 1995.
9. Baker, E. T., G. J. Massoth, J. E. Lupton, S. L. Walker, D. A. Tennant, C. Wilson, and N. Garfield, Time-series sampling of hydrothennal event plume(s) from tbe 1996 Gorda Ridge eruption, EOS Trans. Am. Geophys. Union, 77, 46, Fall Meeting suppl., FI, 1996.
10. Baker, E. T., G. J. Massoth, J. E. Lupton, S. L. Walker, D. A. Tennant, C. Wilson, and N. Garfield, Pattems of event and chronic hydrothermal venting following a magmatic intrusion: New perspective from the 1996 Gorda Ridge eruption, Deep-Sea Res., in press.
11. Baker, E. T., and T. Urabe, Extensive distribution of hydrothennal plumes along the superfast spreading East Pacific Rise, 13o13'-18o40'S, J. Geophys. Res., 101, 8685-8695, 1996.
12. Ballard, R. D., W. B. Bryan, J. R. Heirtzler, G. R. Keller, J. G. Moore, and T. H. van Andel, Manned submersible observations in the Famous area, Science, 190, 103-108, 1975.
13. Ballard, R. D., J. Francheteau, T. Juteau, C. Rangan, and W. Normark, East Pacific Rise at 21°N: the volcanic, tectonic, and hydrothermal processes of the central axis, Earth Planet. Sci. Lett., 55, 1-10, 1981.
14. Ballard, R. D., R. Hekinian, and J. Francheteau, Geological setting of hydrothermal activity at 12°50'N on the East Pacific Rise: a submersible study, Earth Planet. Sci. Lett., 69, 176-186, 1984.
15. Ballard, R. D., R. T. Holcomb, and T. H. van Andel, The Galapagos Rift at 86°W: 3. Sheet flows, collapse pits, and lava lakes of the rift valley, J. Geophys. Res., 84, 5407-5422, 1979.
16. Ballard, R. D., and J. G. Moore, Photographic Atlas of the Mid-Atlantic Ridge Rift Valley, 114 pp., Springer-Verlag, New York, 1977.
17. Ballard, R. D., and T. H. van Andel, Morphology and tectonics of the inner rift valley at 36°50'N on the Mid-Atlantic Ridge, Geol. Soc. Am. Bull., 88, 507-530, 1977.
18. Ballard, R. D., T. H. van Andel, and R. T. Holcomb, The Galapagos Rift at 86°W: 5. Variations in volcanism, structure, and hydrothermal activity along a 30-kilometer segment of the rift valley, J. Geophys. Res., 87, 1149-1161, 1982.
19. Barone, A. M., and W. B. F. Ryan, Single plume model for asynchronous formation of the Lamont seamounts and adjacent East Pacific Rise terrain, J. Geophys. Res., 95, 10801-10827, 1990.
20. Barr, S. M., Seamount chains formed near the crest of Juan de Fuca Ridge, northeast Pacific Ocean, Mar. Geol., 17, 1-19, 1974.
21. Batiza, R., P. J. Fox, P. R. Vogt, S. C. Cande, N. R. Grindlay, W. G. Melson, and T. O. O'Heam, Morphology, abundance, and chemistry of near-ridge seamounts in the vicinity of the Mid-Atlantic Ridge ~26°S, J. Geology, 97, 209-220, 1989.
22. Batiza, R., and Y. Niu, Petrology and magma chamber processes at the East Pacific Rise-9°30'N, J. Geophys. Res., 97, 6779-6797, 1992.
23. Batiza, R., Y. Niu, J. L. Karsten, W. Boger, E. Potts, L. Norby, and R. B útla, Steady and non-steady state magma chambers below the East Pacific Rise, Geophys. Res. Lett., 23, 221- 224, 1996.
24. Batiza, R., and D. Vanko, Volcanic development of small oceanic centrál volcanoes on the flanks of the East Pacific Rise inferred from narrow-beam echo-sounder surveys, Mar. Geol., 54, 53-90, 1983.
25. Bennett, J. T., S. Krishnaswami, K. K. Turekian, W. G. Melson, and C. A. Hopson, The uranium and thorium decay series nuclides in Mt St. Helens effusives, Earth Planet. Sci. Lett., 60, 1982.
26. Bergman, E. A., and S. C. Solomon, Earthquake swarms on the Mid-Atlantic Ridge: Products of magmatism or extensional tectonics?, J. Geophys. Res., 95, 4943-4965, 1990.
27. Bjômsson, A., G. Johnsen, S. Sigurdsson, G. Thorbergsson, and E. Tryggvason, Rifting of the plate boundary in north Iceland, 1975-1978, J. Geophys. Res., 84, 3029-3038, 1979.
28. Bonatti, E., and C. G. A. Hanison, Eruption styles of basalt in oceanic spreading ridges and seamounts: Effect of magma temperature and viscosity, J. Geophys. Res., 93, 2967-2980, 1988.
29. Brandsdottir, B., and P. Einarsson, Seismic activity associated with the September 1977 deflation of the Krafla central volcano in northeastem Iceland, J. Volcanol. Geotherm. Res., 6, 197-212, 1979.
30. Brown, J. R., and J. A. Karson, Variations in axial processes on the Mid-Atlantic Ridge: The median valley of the MARK area, Mar. Geophys. Res., 10, 109-138, 1988.
31. Bryan, W. B., S. E. Humphris, G. Thompson, and J. F. Casey, Comparative volcanology of small axial eruptive centers in the MARK area, J. Geophys. Res., 99, 2973-2984, 1994.
32. Bryan, W. B., and J. G. Moore, Compositional variations of young basalts in the Mid-Atlantic Ridge rift valley near 36°49 N, Bull. Geol. Soc. Amer., 88, 556-570, 1976.
33. Bryan, W. B., and G. Thompson, Basalts from DSDP Leg 37 and the FAMOUS area: compositional and petrogenetic compari so ns, Can. J. Earth Sci., 14, 875-885, 1977.
34. Bryan, W. B., G. Thompson, and J. N. Ludden, Compositional variation in normal MORB from 22*-25°N: Mid-Atlantic Ridge and Kane fracture zone, J. Geophys. Res., 86, 11, 815-11, 836, 1981.
35. Bryan, W. B., G. Thompson, and P. J. Michael, Compositional variation in a steady-state zoned magma chamber: Mid-Atl antic Ridge at 36° 50'N, Tectonophysics, 55, 63-85, 1979.
36. Butterfield, D. A., K K Roe, J. Ishibashi, and J. E. Lupton, Time series chemistry of hydrothermal fluids Írom the southem East Pacific Rise, 14-18°S, EOS Trans. Am. Geophys. Union, 78, 46, Fall Meeting suppl., F706, 1997.
37. Can ales, J. P., J. J. Dafiobeitia, R. S. Detrick, E. E. E. Hooft, R. Bartolomé, and D. F. Naar, Variations in axial morphology along the Galapagos spreading center and the influence of the Galapagos hotspot, J. Geophys. Res., 102, 27341-27354, 1997.
38. Cann, J. R., and M. R. Strens, Modeling periodic megaplume emission by black smoker systems, J. Geophys. Res., 94, 12227-12237, 1989.
39. Carbotte, S., and K C. Macdonald, Comparison of seafloor tectonic fabric at intermediate, fast, and superiast spreading ridges: Influence of spreading rate, plate motions, and ridge segmentation on fault patterns, J. Geophys. Res., 99, 13609-13631, 1994.
40. Carbotte, S. M., J. C. Mutter, and L. Xu, Contribution of volcanism and tectonism to axial and flank morphology of the southem East Pacific Rise, 17S10,-17°40'S, from a study of layer 2A geometry, J. Geophys. Res., 102, 10165-10184, 1997.
41. Chadwick, W. W., Jr., and R. W. Embley, Lava flows from a mid-1980s submarine eruption on the Cleft Segment, Juan de Fuca Ridge, J. Geophys. Res., 99, 4761-4776, 1994.
42. Chadwick, W. W., Jr., and R. W. Embley, Graben formation associated with recent dike intrusions and volcanic eruptions on the mid-ocean ridge, J. Geophys. Res., in press.
43. Chadwick, W. W., Jr., R. W. Embley, and C. G. Fox, Evidence for volcanic eruption on the southem Juan de Fuca Ridge between 1981 and 1987, Nature, 350, 416-418, 1991.
44. Chadwick, W. W., Jr., R. W. Embley, and C. G. Fox, SeaBeam depth changes associated with recent lava flows, CoAxial segment, Juan de Fuca Ridge: Evidence for multiple eruptions between 1981-1993, Geophys. Res. Lett., 22, 167-170, 1995. observations in the Famous area, Science, 190, 103-108, 1975.
45. Chadwick, W. W., Jr., R. W. Embley, and T. M. Shank, The 1996 Garda Ridge eruption: Geologic mapping, sidescan sonar, and SeaBeam comparison results, Deep-Sea Res., in press.
46. Choukroune, P., J. Francheteau, and R. Hekinian, Tectonics of the East Pacific Rise near 12°50'N: A submersible study, Earth Planet. Sci. Lett., 68, 115-127, 1984.
47. Christeson, G. L., G. M. Purdy, and G. J. Fryer, Seismic constraints on shallow crustal emplacement processes at the fast spreading East Pacific Rise, J. Geophys. Res., 99, 17957-17973, 1994.
48. Christie, D., and J. Sinton, Evolution of abyssal lavas along propagating segments of the Galapagos spreading center, Earth Planet. Sci. Let., 56, 321-335, 1981.
49. Clague, D. A., F. A. Frey, G. Thompson, and S. Rindge, Minor and trace-element geochemistry of volcanic rocks dredged from the Galapagos spreading center: Role of crystal fractionation and mantie heterogeneity, J. Geophys. Res., 86, 9469-9482, 1981.
50. Cochran, J. R., et al., The Southeast Indián Ridge between 88°E and 118°E: Gravity anomalies and crustal accretion at intermediate spreading rates, J. Geophys. Res., 102, 15463-15487, 1997.
51. Condomines, M., Comment on: "The volume and residence time of magma beneath active volcanoes determined by decay series disequilibria methods", Earth Planet. Sci. Lett., 122, 251-255, 1994.
52. Condomines, M., C. Hemond, and C. J. Allégre, U-Th-Ra radioactive disequilibria and magmatic processes, Earth Planet. Sci. Lett., 90, 243-262, 1988.
53. Crane, K., and R. D. Ballard, Volcanic« and structure of the Famous Narrowgate Rift Evidence far cyclic evolution: AMAR 1, J. Geophys. Res., 86, 5112-5124, 1981.
54. Crisp, J. A., Rates of magma emplacement and volcanic output, J. Volcanol. Geotherm. Res., 20, 177-211, 1984.
55. Davis, E., Evidence for extensive basalt flows on the sea floor, Geol. Soc. Am. Bull., 93, 1023-1029, 1982.
56. Davis, E., and H. Villinger, Tectonic and thermal structure of the Middle Valley sedimented rift, northern Juan de Fuca Ridge, in Proceedings of the Ocean Drilling Program, Iniţial Reports, v. 139, edited by E. E. Davis, et al., pp. 9-41, Ocean Drilling Program, College Station, TX, 1992.
57. Davis, E. E., and J. L. Kare ten, On the cause of the asymmetric distribution of seamounts about the Juan de Fuca Ridge: Ridge-crest migration over a heterogeneous asthenosphere, Earth Planet. Sci. Lett., 79, 385-396, 1986.
58. Detrick, R. S., P. Buhl, E. Vera, J. Mutter, J. Orcutt, J. Madsen, and T. Brocher, Multi-channel seismic imaging of a crustal magma chamber along the East Pacific Rise, Nature, 326, 35-41, 1987.
59. Detrick, R. S., A. J. Harding, G. M. Kent, J. A. Orcutt, J. C. Mutter, and P. Buhl, Seismic structure of the Southern East Pacific Rise, Science, 259, 499-503, 1993.
60. Detrick, R. S., J. C. Mutter, P. Buhl, and I.I. Kim, No evidence from multichannel reflection data for a crustal magma chamber in the MARK area on the Mid-Atlantic Ridge, Nature, 347, 61-64, 1990.
61. 39Ar incremental be ating method, Geophys. Res. Lett., 21, 1927-1930, 1994.
62. Dziak, R. P., and C. G. Fox, Long-term seismicity and ground deformation at Axial volcano, Juan de Fuca Ridge, EOS Trans. Am. Geophys. Union, 78, 46, Fall Meeting suppl., F641, 1997.
63. Dziak, R. P., C. G. Fox, R. W. Embley, J. E. Lupton, G. Johnson, W. W. Chadwick Jr., and R. A. Koski, Detection of and response to a probable volcanogenic T-wave event swarm on the western Blanco Transform Fault Zone, Geophys. Res. Lett., 23, 873-876, 1996.
64. Dziak, R. P., C. G. Fox, and A. E. Schreiner, The June-July 1993 seismo-acoustic event at CoAxial segment, Juan cb Fuca Ridge: Evidence for a lateral dike injection, Geophys. Res. Lett., 22, 135-138, 1995.
65. Einarsson, P., and B. Brandsdottir, Seismological evidence for lateral magma intrusion during the July 1978 deflation of the Krafla volcano in NE-Iceland, J. Geophys., 47, 160-165, 1980.
66. Einsele, G., Bas al tic sill-sediment complexe« in young spreading centers: Genesis and significance, Geology, 13, 249-252, 1985.
67. Embley, R. W., and W. W. Chadwick Jr., Volcanic and hydrothermal processes associated with a recent phase of seafloor spreading at the northern Cleft segment: Juan de Fuca Ridge, J. Geophys. Res., 99, 4741-4760, 1994.
68. Embley, R. W., W. W. Chadwick Jr., and J. Getsiv, The CoAxial segment: A site of recent seafloor eruptions on the Juan de Fuca Ridge, EOS Trans. Am. Geophys. Union, 76, 46, Fall Meeting suppl., F410, 1995a.
69. Embley, R. W., W. W. Chadwick Jr., I. R. Jonasson, D. A. Butterfield, and E. T. Baker, Iniţial results of the rapid response to the 1993 CoAxial event: Relationships between hydrothermal and volcanic processes, Geophys. Res. Lett., 22, 143-146, 1995b.
70. Embley, R. W., W. W. Chadwick Jr., M. R. Perfit, and E. T. Baker, Geology of the northem Cleft segment, Juan de Fuca Ridge: Recent lava flows, sea-floor spreading, and the formation of megaplumes, Geology, 19, 771-775, 1991.
71. Embley, R. W., W. W. Chadwick Jr., T. Shank, and D. Christie, Geology of the 1996 Gorda Ridge eruption from analysis of multibeam, towed camera, sidescan, and ROV data, EOS Trans. Am. Geophys. Union, 77, 46, Fall Meeting suppl., FI, 1996.
72. Embley, R. W., J. E. Lupton, G. Massoth, T. Urabe, T. Shibata, V. Tunnicliffe, D. Butterfield, O. Okano, M. Kinoshita, and K. Fujioka, Geologic, chemical, and biologic evidence for recent volcanism at 17#22'-35'S, East Pacific Rise, Earth Planet. Sci. Lett., in press.
73. Embley, R. W., J. E. Lupton, G. Massoth, T. Urabe, V. Tunnicliffe, D. A. Butterfield, T. Shibata, O. Okano, M. Kinoshita, and K. Fujioka, Geologic, chemical, and biologic evidence for recent volcanism at 17.5°S, EOS Trans. Am. Geophys. Union, 78, 46, Fall Meeting suppl., F705, 1997.
74. Embley, R. W., K. M. Murphy, and C. G. Fox, High resolution studies of the summit of Axial volcano, J. Geophys. Res., 95, 12785-12812, 1990.
75. Feely, R. A., E. T. Baker, K. Maramo, T. Urabe, J. Ishibashi, J. Gendron, G. T. Lebon, and K. Okamura, Hydrothermal plume particles and dissolved phosphate over the superfast-spreading southem East Pacific Rise, Geoch. Cosmoch. Acta, 60, 2297-2323, 1996.
76. Fink, J. H., and R. W. Griffiths, Radi al spreading of viscous-gravity currents with solidifying crust, J. Fluid Mech, 221, 485-509, 1990.
77. Fink, J. H., and R. W. Griffiths, A laboratory analog study of tbe surface morphology of lava flows extruded from point and line sources, J. Volcanol. Geotherm. Res., 54, 19-32, 1992.
78. Fomari, D. J., R. Batiza, and M. A. Luckman, Seamount abundances and distribution near tbe East Pacific Rise 0°-24°N based on Seabeam data, in Seamounts, Islands, and Atolls, edited by: B. Keating, et al., pp. 13-21, American Geophysical Union, Washington, DC, 1987.
79. Fomari, D. J., and R. W. Embley, Tectonic and volcanic Controls on hydrothermal processes at the mid-ocean ridge: An overview based on near-bottom and submersible studies, in Seafloor Hydrothermal Systems: Pkysical, Chemical, Biological, and Geological Interactions, Geophys. Monograph 91, edited by S. E. Humphris, et al., pp. 1-46, American Geophysical Union, Washington, DC, 1995.
80. Fomari, D. J., R. M. Haymon, M. R. Perfit, T. K. P. Gregg, and M. H. Edwards, Axial summit trough of the East Pacific Rise 9°N to 10°N: Geological characteristics and evolution of the axial zone on fast-spreading mid-ocean ridges, J. Geophys. Res., in press-a.
81. Fomari, D. J., M. R. Perfit, J. F. Allan, R. Batiza, R. Haymon, A. Barone, W. B. F. Ryan, T. Smith, T. Simkin, and M. A. Luckman, Geochemical and structural studies of the Lamont seamounts: Seamounts as indicators of mantie processes, Earth Planet. Sci. Lett., 89, 63-83, 1988.
82. Fomari, D. J., W. B. F. Ryan, and P. J. Fox, The evolution of craters and calderas on young seamounts: Insights from Sea Marc I and SeaBeam sonar surveys of a small seamount group near the axis of tbe East Pacific Rise at 10°N, J. Geophys. Res., 89, 11069-11083, 1984.
83. Fomari, D. J., T. Shank, K. L. Von Damm, T. K. P. Gregg, M. Lilley, G. Levai, A. Bray, R. M. Haymon, M. R. Perfit, and R. Lutz, Time-series temperature measurements at high-temperature hydrothennal vents, East Pacific Rise 9°49-5ľN: Monitoring a crustal cracking event, Earth Planet. Sci. Lett., in press-b.
84. Fox, C. G., Evidence of active ground deformation on tbe mid-ocean ridge: Axial Seamount, Juan de Fuca Ridge, April-June, 1988, J. Geophys. Res., 95, 12813-12822, 1990.
85. Fox, C. G., Five years of ground defonnation monitoring on Axial Seamount using a bottom pressure recorder, Geophys. Res. Lett., 20, 1859-1862, 1993.
86. Fox, C. G., W. W. Chadwick Jr., and R. W. Embley, Detection of changes in ridge-crest morphology using repeated multibeam sonar surveys, J. Geophys. Res., 97, 11149-11162, 1992.
87. Fox, C. G., and R. P. Dziak, Seismo-acoustic detection of volcanic activity on the Gorda Ridge, February-March 1996, EOS Trans. Am. Geophys. Union, 77, 46, Fall Meeting suppl., Fl, 1996.
88. Fox, C. G., and R. P. Dziak, Hydioacoustic detection of volcanic activity on the Gorda Ridge, February-March 1996, Deep-Sea Res., in press.
89. Fox, C. G., R. P. Dziak, H. Matsumoto, and A. E. Schreiner, Potential for monitoring low-level seismicity on the Juan de Fuca Ridge using military hydrophone arrays, Mar. Tech. Soc. J., 27, 22-30, 1994.
90. Fox, C. G., and H. Matsumoto, Monitoring northeast Pacific seismicity using autonomous hydrophone moorings, EOS Trans. Am. Geophys. Union, 76, 46, Fall Meeting suppl., F412, 1995.
91. Fox, C. G., H. Matsumoto, and T. K. Lau, Monitoring East Pacific Rise seismicity using autonomous hydrophone moorings, EOS Trans. Am. Geophys. Union, 78, 46, Fall Meeting suppl., F705, 1997.
92. Fox, C. G., K. M. Muiphy, and R. W. Embley, Automated display and statistical analysis of interpreted deep-sea bottom photographs, Mar. Geol., 78, 199-216, 1988.
93. Fox, C. G., W. E. Radford, R. P. Dziak, T. K. Lau, H. Matsumoto, and A. E. Schreiner, Acoustic detection of a seafloor spreading episode on the Juan de Fuca Ridge using military hydrophone arrays, Geophys. Res. Lett., 22, 131-134, 1995.
94. Fox, P. J., N. R. Grindlay, and K. C. Macdonald, The Mid-Atlantic Ridge (31°S-34°30'S): Temporal and spaţial variations of accretionary processes, Mar. Geophys. Res., 13, 1-20, 1991.
95. Francheteau, J., and R. D. Ballard, Tbe East Pacific Rise near 21 °N, 13°N and 20°S: Inferences for along-strike variability of axial processes of the mid-ocean ridge, Earth Planet. Sci. Lett., 64, 93-116, 1983.
96. Francheteau, J., T. Juteau, and C. Rangan, Basaltic pillars in collapsed lava-pools on tbe deep ocean-floor, Nature, 281, 209-211, 1979.
97. Frey, F. A., N. Walker, D. Stakes, S. R. Hart, and R. Nielsen, Geochemical characteristics of basaltic glasses from tbe AMAR and FAMOUS axial valleys, Mid-Atlantic Ridge (36°-37°N): Petrogenetic implications, Earth Planet. Sci. Lett., 115, 117-136, 1993.
98. Fujimoto, H., N. Seama, J. Lin, T. Matsumoto, T. Tanaka, and K. Fujioka, Gravity anomalies of the Mid-Atlantic Ridge north of the Kane Fracture Zone, Geophys. Res. Lett., 23, 3431-3434, 1996.
99. Garcia, M. O., K. H. Rubin, M. D. Norman, J. M. Rhodes, D. W. Graham, K. Spencer, and D. Muenow, Petrology and geochronology of basalt breccia from the 1996 earthquake swarm of Loihi Seamount, Hawaii: Magmatic history of its 1996 eruption, Bull. Volcanol., in press.
100. Gente, P., J. M. Auzende, V. Renard, Y. Fouquet, and D. Bideau, Detailed geological mapping by submersible of the East Pacific Rise axial graben near 13°N, Earth Planet. Sci. Lett., 78, 224-236, 1986.
101. Gente, P., C. Mével, J. M. Auzende, J. A. Karson, and Y. Fouquet, An example of a recent accretion on the Mid-Atlantic Ridge: The Snakepit neovolcanic ridge (MARK area, 23°22'N), Tectonophysics, 190, 1-29, 1991.
102. Gill, J., and M. Condomines, Short-lived radioactivity and magma genesis, Science, 257, 1368-1376, 1992.
103. Gill, J., D. M. Pyle, and R. W. Williams, Igneous Rocks, 207-257 pp., Oxford Science Publications, Oxford, U.K., 1992.
104. Gill, J., R. Williams, and K. Bruland, Eruption of basalt and andesite lava degasses “Rn and I10Po., Geophys. Res. Lett., 12, 17-20, 1985.
105. Goldstein, S. J., M. T. Murrell, and D. R. Janecky, Th and U isotopic systematics of basalts from the Juan de Fuca and Gorda Ridges by mass spectrometry, Earth Planet. Sci. Lett., 96, 134-146, 1989.
106. Goldstein, S. J., M. T. Murrell, D. R. Janecky, J. R. Delaney, and D. A. Clague, Geochronology and petrogenesis of MORB from the Juan de Fuca and Gorda ridges by 23,U-U0Th disequilibrium, Earth Planet. Sci. Lett., 109, 255-272, 1992.
107. Goldstein, S. J., M. T. Murrell, and R. W. Williams, aiPa and ““Th chronology of mid-ocean ridge basalts, Earth Planet. Sci. Lett., 115, 151-159, 1993.
108. Goldstein, S. J., M. R. Perfit, R. Batiza, D. J. Fomari, and M. T. Murrell, 2MRa and “'Pa systematics of axial MORB, crustal residence ages, and magma chamber characteristics at 9,-10°N, East Pacific Rise, Mineralogical Magazine, 58a, 335-336, 1994a.
109. Goldstein, S. J., M. R. Perfit, R. Batiza, D. J. Fomari, and M. T. Murrell, Off-axis volcanism at the East Pacific Rise detected by uranium-series dating of basalts. Nature, 367, 157-159, 1994b.
110. Goodfellow, W. D., and J. M. Franklin, Geology, mineralogy, and chemistry of sediment-hosted clastic massive sulfides in shallow cores, Middle Valley, northern Juan de Fuca Ridge, Econ. Geol., 88, 2037-2068, 1993.
111. Green, J., and N. M. Short, Volcanic landforms and surface features, 519 pp., Springer, Berlin, Heidelberg, New York, 1971.
112. Gregg, T. K. P., and W. W. Chadwick Jr., Submarine lava-fiow inflation: A model for the formation of lava pillars, Geology, 24, 981-984, 1996.
113. Gregg, T. K. P., and J. H. Fink, Quantification of submarine lava-flow morphology through analog experiments, Geology, 23, 73-76, 1995.
114. Gregg, T. K. P., D. J. Fornari, and M. R. Perfit, Lava pillars: "Rosetta stones" of deep sea eruption dynamics, EOS Trans. Am. Geophys. Union, 77, 46, Fall Meeting suppl., F664, 1996a.
115. Gregg, T. K. P., D. J. Fornari, M. R. Perfit, R. M. Haymon, and J. H. Fink, Rapid emplacement of a mid-ocean ridge lava flow on the East Pacific Rise at 9° 46'-5ľN, Earth Planet. Sci. Lett., 144, E1-E7, 1996b.
116. Griffiths, R. W., and J. H. Fink, Solidification and morphology of submarine lavas: A dependence on extrusion rate, J. Geophys. Res., 97, 19729-19737, 1992.
117. Grindlay, N. R., P. J. Fox, and P. R. Vogt, Morphology and tectonics of the Mid-Atlantic Ridge (25o-27°30'S) from SeaBeam and magnetic data, J. Geophys. Res., 97, 6983-7010, 1992.
118. Grove, T. L., R. J. Kinzler, and W. B. Bryan, Fractionation of mid-ocean ridge basalts, in Mantie flow and melt generation at mid-ocean ridges, Geophys. Monograph 71, edited by J. Phipps-Morgan, D. K. Blackman, and J. Sinton, pp. 281-310, Am. Geophys. Union, Washington, D.C., 1992.
119. Hall, L. S., and J. M. Sinton, Geochemical diversity of the large lava field on the flank of the East Pacific Rise at 8°17’S, Earth Planet. Sci. Lett., 142, 241-251, 1996.
120. Hammond, S. R., Offset caldera and crater collapse on Juan de Fuca ridge-flank volcanoes, Bull. Volcanol., 58, 617-627, 1997.
121. Harding, A. J., G. M. Kent, and J. A. Orcutt, A multichannel seismic investigation of upper crustal structure at 9°N on the East Pacific Rise: Implications for crustal accretion, J. Geophys. Res., 98, 13925-13944, 1993.
122. Harp, K. S., Geochemical variations in a single basal tie flow at 9°30’N on the East Pacific Rise, in Proc. ODP, Sci Results, 142, edited by R. Batiza Storm s, M.A., and Allan, J.F., pp. 9-21, Ocean Drilling Program, College Station, Texas, 1995.
123. Hart, S. R., A large-scale isotope anomaly in the Southem Hemisphere mantie, Nature, 309, 753-757, 1984.
124. Haymon, R., D. J. Fomari, M. H. Edwards, S. Carbotte, D. Wright, and K. C. Macdonald, Hydrothennal vent distribution along the East Pacific Rise crest (9°09'-54'N) and its relationship to magmatic and tectonic processes on fast-spreading mid-ocean ridges, Earth Planet. Sci. Lett., 104, 513-534, 1991.
125. Haymon, R. M., et al., Volcanic eruption of the mid-ocean ridge along the East Pacific Rise crest at 9C 45-52'N: Direct submersible observations of seafloor phenomena associated with an eruption event in April, 1991, Earth Planet. Sci. Lett., 119, 85-101, 1993.
126. Head, J. W., L. Wilson, and D. K. Smith, Mid-ocean ridge eruptive vents: Evidence for dike widths, eruption rates, and evolution of eruptions from morphology and structure, J. Geophys. Res., 101, 28265-28280, 1996.
127. Hekinian, R., J. M. Auzende, J. Francheteau, P. Gente, W. B. F. Ryan, and E. S. Kappel, Offset spreading centers near 12°53' N on the East Pacific Rise: submersible observations and composition of the volcanics, Marine Geophys. Res., 7, 359-377, 1985.
128. Hekinian, R., et al., East Pacific Rise near 13°N: geology of new hydrothermal fields, Science, 219, 1321-1324, 1983.
129. Hekinian, R., G. Thompson, and D. Bideau, Axial and off-axial heterogeneity of basal tie rocks from the East Pacific Rise at 12°35'N-12#51'N and ll#26N-llo30'N, J. Geophys. Res., 94, 17,437-17,463, 1989.
130. Hekinian, R., and D. Walker, Diversity and spaţial zonation of volcanic rocks from the East Pacific Rise near 21°N, Contrib. Mineral. Petrol., 96, 265-280, 1987.
131. Hey, R., P. D. Johnson, F. Martinez, J. Korenaga, M. L. Somers, Q. J. Huggett, T. P. LeBas, R. I. Rusby, and D. F. Naar, Plate boundary reorganiza tion at a large-offset, rapidly propagating rift. Nature, 378, 167-170, 1995.
132. Holden, J. F., B. C. Crump, M. Summit, and J. A. Baros s, Microbial blooms at the CoAxial segment, Juan de Fuca Ridge deep-sea hydrothennal vent site following a magma intrusion, EOS Trans. Am. Geophys. Union, 76, 43, Fall Meet. Suppl., F411, 1995.
133. Hon, K., J. Kauahikaua, R. Denlinger, and K. Mackay, Emplacement and inflation of pahoehoe sheet flows: Observations and measurements of active lava flows on Kilauea volcano. Hawaii, Geol. Soc. Am. Bull., 106, 351-370, 1994.
134. Hooft, E. E. E., and R. S. Detrick, Relationship between axial morphology, crustal thickness, and mantie temperature along the Juan de Fuca and Gorda Ridges, J. Geophys. Res., 100,22499-22508, 1995.
135. Hooft, E. E. E., R. S. Detrick, and G. M. Kent, Seismic structure and indicators of magma budget along the southem East Pacific Rise, J. Geophys. Res., 102, 27319-27340, 1997.
136. Hooft, E. E. E., H. Schouten, and R. S. Detrick, Constraining crustal emplacement processes from the variation of seismic layer 2A thickness at the East Pacific Rise, Earth Planet. Sci. Lett., 142, 289-310, 1996.
137. Humler, E., J. L. Thirot, and J. P. Montagner, Global conelations of mid-ocean ridge basalt chemistry with seismic tomographic images, Nature, 364, 225-228, 1993.
138. Humphris, S. E., W. B. Bryan, G. Thompson, and L. K. Autio, Morphology, geochemistry, and evolution of Serocki volcano, in Proc. Ocean Drilling Prog., Scientific Results, 106/109, edited by R. S. Detrick, et al., pp. 67-84, Ocean Drilling Program, College Station, Texas, 1990.
139. Johnson, P. D., Recent structural evolution of the East Pacific Rise 29°S large-scale dueling propagator system, M.A. Thesis, University of Hawaii, 1996.
140. Juniper, S. K., P. Martineu, J. Sarrazin, and Y. Gélinas, Microbial-mineral floc associated with nascent hydrothermal activity on CoAxial segment, Juan de Fuca Ridge, Geophys. Res. Lett., 22, 179-182, 1995.
141. Juster, T. C., T. L. Grove, and M. R. Perfit, Experimental constraints on the generation of FeTi basalts, andesites and rhyodacites at the Galapagos Spreading Center, 85° and 95° W, J. Geophys. Res., 94, 9251-9274, 1989.
142. Kappel, E. S., and W. R. Normark, Morphometric variability within the axial zone of the Southern Juan de Fuca Ridge: Intcrpretation from SeaMARC n, SeaMARC I, and deep sea photography, J. Geophys. Res., 92, 11,291-11,302, 1987.
143. Kappel, E. S., and W. B. F. Ryan, Volcanic episodicity and a non-steady state rift valley along northeast Pacific spreading centers: evidence from SeaMARC I, J. Geophys. Res., 91, 13925-13940, 1986.
144. Karson, J. A., and P. A. Rona, Block-tilting, transfer faults, and structural control of magmatic and hydrothermal processes in the TAG area, Mid-Atlantic Ridge 26°N, Geol. Soc. Am. Bull., 102, 1635-1645, 1990.
145. Karson, J. A., et al., Along-axis variations in seafloor spreading in tbe MARK area. Nature, 328, 681-685, 1987.
146. Karsten, J. L., J. R. Delaney, J. M. Rhodes, and R. A. Liias, Spaţial and temporal evolution of magmatic systems beneath the Endeavour segment, Juan de Fuca Ridge: Tectonic and petrologie constraints, J. Geophys. Res., 95, 19,235-19,256, 1990.
147. Karsten, J. L., S. R. Hammond, E. E. Davis, and R. G. Currie, Detailed geomorphology and neotectonics of the Endeavour segment, Juan de Fuca Ridge: New results from Seabeam swath mapping, GeoL Soc. Am. Bull., 97, 213-221, 1986.
148. Kent, G. M., A. J. Harding, and J. A. Orcutt, Distribution of magma beneath the East Pacific Rise between the Clipperton Transform and the 9°17'N deval from forward modeling of common depth point data, J. Geophys. Res., 98, 13945-13969, 1993.
149. Klein, E. M., and C. H. Langmuir, Global correlations of ocean ridge basalt chemistry with axial depth and crustal thickness, J. Geophys. Res., 92, 8089-8115, 1987.
150. Klein, E. M., and C. H. Langmuir, Local versus global variations in ocean ridge basalt composition: A reply, J. Geophys. Res., 94, 4241-4252, 1989.
151. Kong, L. S., R. S. Detrick, P. J. Fox, L. A. Mayer, and W. B. F. Ryan, The morphology and tectonics of the MARK area from SeaBeam and Sea MARC I observations (Mid-Atlantic Ridge 23°N), Mar. Geophys. Res., 10, 59-90, 1988.
152. Kuo, B. Y., and D. W. Foisyth, Gravity anomalies of the ridge-transform system in the south Atlantic between 31 and 34.5°S: Upwelling centers and variation in crustal thickness, Mar. Geophys. Res., 10, 205-232, 1988.
153. Lagabrielle, Y., M. H. Cormier, V. Ballu, and J. M. Auzende, From perfect dome to large collapse caldera: Tectonic/magmatic evolution of the EPR axial domain at 17°-19°S from submersible observations, EOS Trans. Am. Geophys. Union, 77, 46, Fall Meeting suppl., F660, 1996.
154. Langmuir, C. H., Petrology database, voi. 2 and voi. 3, in East Pacific Rise Data Synthesis Final Report, edited by S. Tighe, Joint Oceanographic Institutions, Inc., Washington, D.C., 1988.
155. Langmuir, C. H., J. F. Bender, and R. Batiza, Petrologie and tectonic segmentation of the East Pacific Rise, 5* 30'-14° 30' N, Nature, 322, 422-429, 1986.
156. Langmuir, C. H., E. M. Klein, and T. Plank, Petrological systematics of mid-ocean ridge basalts: constraints on melt generation beneath ocean ridges, in Mantie flow and melt generation at mid-ocean ridges, Geophys. Monograph 71, edited by J. Phipps-Morgan, D. K. Blackman, and J. Sinton, pp. 183-280, Amer. Geophys. Union, Washington, D.C., 1992.
157. Roex, A. P., F. A. Frey, and S. H. Richardson, Petrogenesis of lavas from the AMAR valley and Narrowgate region of the FAMOUS valley, 36°-37°N on tbe Mid-Atlantic Ridge, Contrib. Mineral. Petrol., 124, 167-184, 1996.
158. Leyboume, M. I., and N. A. Van Wagoner, Heck and Heckle seamounts, northeast Pacific Ocean: high extrusion rates of primitive and highly depleted mid-ocean ridge basalt on off-ridge seamounts, J. Geophys. Res., 96, 16,275-16,293, 1991.
159. Lin, J., G. M. Purdy, H. Schouten, J. C. Sempéré, and C. Zervas, Evidence from gravity data for focused magmatic accretion along the Mid-Atlantic Ridge, Nature, 344, 627-632, 1990.
160. Lister, C. R. B., On the intermittency and crystallization mechanisms of sub-seafloor magma chambers, Geophys. J. R. Astr. Soc., 73, 351-365, 1983.
161. Lonsdale, P., Abyssal pahoehoe with lava coils at the Galapagos Rift, Geology, 5, 147-152, 1977a.
162. Lonsdale, P., Structural geomorphology of a fast-spreading rise crest: The East Pacific Rise near 3°25'S, Mar. Geophys. Res., 3, 251-293, 1977b.
163. Lonsdale, P., Segmentation of tbe Pacific-Nazca spreading center, rN-20°S, J. Geophys. Res., 94, 12197-12225, 1989.
164. Lonsdale, P., and K. Becker, Hydrothermal plumes, hot springs, and conductive heat flow in the Southern trough of Guaymas Basin, Earth Planet. Sci. Lett., 73, 211-225, 1985.
165. Lonsdale, P. F., and L. A. Lawver, Immature plate boundary zones studies with a submersible in the Gulf of California, Geol. Soc. Am. Bull., 91, 555-569, 1980.
166. Lowell, R. P., and L. N. Germanovich, Dike injection and the formation of megaplumes at ocean ridges, Science, 267, 1804-1807, 1995.
167. Lundstrom, C. C., J. Gill, Q. Williams, and M. R. Perfit, Mantie melting and basalt extraction by equilibrium porous flow, Science, 270, 1958-1961, 1995.
168. Lupton, J. E., E. T. Baker, N. Garfield, R. Greene, and T. Rago, Successful tracking of a hydrothermal event plume with a RAFOS neutrally-buoyant drifter, EOS Trans. Am. Geophys. Union, 77, 46, Fall Meeting suppl., Fl, 1996.
169. Lupton, J. E., J. C. Ishibashi, and D. A. Butterfield, Gas chemistry of hydrothennal fluids along tbe Southern East Pacific Rise, 13.5-18.5°S, EOS Trans. Am. Geophys. Union, 78, 46, Fall Meeting suppl., F706, 1997.
170. Luyendyk, B. P., and K. C. Macdonald, A geological transect across the crest of the East Pacific Rise at 21°N latitude made from the deep submersible Alvin, Mar. Geophys. Res., 7, 467-488, 1985.
171. Macdonald, K. C., Mid-ocean ridges: Fine scale tectonic, volcanic and hydrothennal processes within the plate boundary zone, Rev. Earth Planetary Sci., 10, 155-190, 1982.
172. Macdonald, K. C., The «rest of the Mid-Atlantic Ridge: Models for crustal generation processes and tectonics, in The Geology of North America: The Western North Atlantic Region, edited by P. R. Vogt, and B. E. Tucholke, pp. 51-68, Geological Society of America, Boulder, CO, 1986.
173. Macdonald, K. C., and P. J. Fox, The axial summit graben and cross-sectional shape of the East Pacific Rise as indicators of axial magma chambers and recent volcanic eruptions, Earth Planet. Sci. Lett., 88, 119-131, 1988.
174. Macdonald, K. C., P. J. Fox, R. T. Alexander, R. Pockalny, and P. Gente, Volcanic growth faults and the origin of Pacific abyssal hills, Nature, 380, 125-129, 1996.
175. Macdonald, K. C., P. J. Fox, L. J. Perram, E. M. F., R. M. Haymon, S. P. Miller, S. M. Carbotte, M.-H. Cormier, and A. N. Shor, A new view of the mid-ocean ridge from the behavior of ridge-axis discontinuities, Nature, 335, 217-225,1988.
176. oS, Geology, 17, 212-216, 1989.
177. Macdonald, K. C., R. M. Haymon, S. M. White, and P. J. Sharfstein, Evidence for extensive lava flows on the southem East Pacific Rise, EOS Trans. Am. Geophys. Union, 78, 46, Fall Meeting suppl., F705, 1997.
178. Macdonald, K. C., D. S. Scheirer, and S. Carbotte, Iťs only topography: Part I, GSA Today, 3, 1 and 24-25, 1993.
179. Macdougall, J. D., Using short-lived U and Th series isotopes to investigate volcanic processes, in Annual Review o f Earth and Planetary Sciences, 23, edited by G. W. Wetherill, A. L. Albee, and K. C. Burice, pp. 143-167, Annual Rev. Inc., Palo Alto, 1995.
180. Mastin, L. G., and D. D. Pollard, Surface deformation and shallow dike intrusion processes at Inyo Craters, Long Valley, California, J. Geophys. Res., 93, 13221-13235, 1988.
181. McConachy, T. F., R. D. Ballard, M. J. Mottl, and R. P. v. Herzen, Geologic form and setting of a hydrothermal vent field at 10e56'N East Pacific Rise: A detailed study using Angus and Alvin, Geology, 14, 295-298, 1986.
182. Melson, W. G., and T. O'Heam, "Zero age" variations in the composition of abyssal volcanic rocks along the axial zone of the Mid-Atlantic Ridge, in The Geology of North America, The Western North America Region, edited by P. R. Vogt, and B. E. Tucholke, pp. 117-136, Geol. Soc. Amer., Boulder, CO, 1986.
183. Michael, P. J., and J.-G. Schilling, Chlorine in mid-ocean ridge magmas: evidence for assimilation of seawater-influenced components, Geochim. et Cosmochim. Acta, 53, 3131-3143, 1989.
184. Moore, J. G., Mechanism of formation of pillow lava. Am. Sci., 63, 269-277, 1975.
185. Morton, J. L., M. L. Holmes, and R. A. Koski, Volcanism and massive sulfide formation at a sedimented spreading center, Escanaba Trough, Gorda Ridge, northeast Pacific Ocean, Geophys. Res. Lett., 14, 769-772, 1987.
186. Morton, J. L., R. A. Zierenberg, and C. A. Reiss, Geologic, hydrothermal, and biologic studies tf Escanaba Trough: An introduc tion, in Geologic, Hydrothermal, and Biologic Studies at Escanaba Trough, Gorda Ridge, Offshore Northem California, U.S. Geol Surv. Bull. 2022, edited by J. L. Morton, R. A. Zierenberg, and C. A. Reiss, pp. 1-20, 1994.
187. Mutter, J. C., S. M. Carbotte, W. Su, L. Xu, P. Buhl, R. S. Detrick, G. M. Kent, J. A. Orcutt, and A. J. Harding, Seismic images of active magma systems beneath the East Pacific Rise between 17°05' and 17a35'S, Science, 268, 391-395, 1995.
188. Mutter, J. C., and J. A. Karson, Structural processes at slow-spreading ridges, Science, 257, 627-634, 1992.
189. Niu, Y., and R. Batiza, Magmatic processes at a slow spreading segment 26° S Mid-Atlantic Ridge, J. Geophys. Res., 99, 19,719-19,740, 1994.
190. Niu, Y., and R. Batiza, Trace element evidence from seamounts for recycled oceanic crust in the Eastem Pacific mantie, Earth Planet. Sci. Lett., 148, 471-483, 1997.
191. Niu, Y., and R. Hekinian, Spreading-rate dependence of the extent of mantie melting beneath ocean ridges, Nature, 385, 326-329, 1997.
192. Normark, W. R., etal. Submarine fissure eruptions and hydrothermal vents on the Southern Juan de Fuca Ridge: Preliminary observations from the submersible Alvin, Geology, 14, 823-827, 1986.
193. Normark, W. R., J. L. Morton, and S. L. Ross, Submersible observations along the southem Juan de Fuca Ridge: 1984 Alvin program, J. Geophys. Res., 92, 11283-11290, 1987.
194. Perfit, M. R., D. J. Fomari, A. Malahoff, and R. W. Embley, Geochemical studies of abyssal lavas recovered by DSRV ALVIN from the eastem Galapagos Rift-Inca Transform-Ecuador Rift: Trace elements and petrogenesis, J. Geophys. Res., 88, 10551-10572, 1983.
195. Perfit, M. R., D. J. Fomari, M. C. Smith, J. F. Bender, C. H. Langmuir, and R. M. Haymon, Small-scale spaţial and temporal variations in mid-ocean ridge crest magmatic processes, Geology, 22, 375-379, 1994.
196. Perfit, M. R., D. J. Fomari, M. C. Smith, C. H. Langmuir, J. F. Bender, and R. M. Haymon, Fine-scale petrological variations along the East Pacific Rise crest 9°17'N to 9S54'N: results from ALVIN diving and rock coring during the Adventure program, Eos Trans. Am. Geophys. Union, 72, 491, 1991.
197. Perfit, M. R., W. I. Ridley, and I. R. Jonasson, Geologic, petrologie and geochemical relationships between magmatism and massive sulfide mineralization along the eastem Galapagos Spreading Center, Rev. Economic Geol., in press.
198. Perfit, M. R., M. C. Smith, K. Sapp, D. J. Fomari, T. Gregg, M. H. Edwards, W. I. Ridley, and J. F. Bender, Geochemistry and Morphology of the Crestai Plateau of the East Pacific Rise-9° 50', Eos Trans. Am. Geophys. Union, 76, F694, 1995.
199. Peterson, D. W., and R. I. Tilling, Transition of basaltic lava from pahoehoe to aa, Kilauea volcano, Hawaii: Field observations and key factors, J. Volcanol. Geotherm. Res., 7, 271-293, 1980.
200. Phipps Morgan, J., and Y. J. Chen, Dependence of ridge-axis morphology on magma supply and spreading rate, Náture, 364, 706-708, 1993a.
201. Phipps Morgan, J., and Y. J. Chen, The genesis of oceanic crust: Magma injection, hydrothermal circulation, and crustal flow, J. Geophys. Res., 98, 6283-6297, 1993b.
202. Pollaid, D. D., P. T. Delaney, P. T. Duffield, E. T. Endo, and A. T. Okamura, Surface deformation in volcanic rift zones, Tectonophysics, 94, 541-584, 1983.
203. Renard, V., R. Hekinian, J. Francheteau, R. D. Ballard, and H. Backer, Submersible observations at tbe axis of the ultra-fast spreading East Pacific Rise (17°30' to 21°30'S), Earth Planet. Sci. Lett., 75, 339-353, 1985.
204. Reynolds, J. A., C. H. Langmuir, J. F. Bender, K. A. Kastens, and W. B. F. Ryan, Spaţial and temporal variability in the geochemistry of basalts from the East Pacific Rise, Nature, 359, 493-499, 1992.
205. Rhodes, J. M., Homogeneity of lava flows: chemical data for histórie Mauna Loan eruptions, J. Geophys. Res., 88, 1983.
206. Rhodes, J. M., M. A. Dungan, D. P. Blanchard, and P. E. Long, Magma mixing at mid-ocean ridges: Evidence from basalts drilled near 22° on the Mid-Atlantic Ridge, Tectonophysics, 55, 35-61, 1979.
207. Rowland, S. K., and G. P. L. Walker, Pahoehoe and aa in Hawaii: Volumetric flow rate Controls the lava structure, Bull. Volcanol., 52, 615-628, 1990.
208. Rubin, A. M., Dike-induced faulting and graben subsidence in volcanic rift zones, J. Geophys. Res., 97, 1839-1858, 1992.
209. Rubin, A. M., and D. D. Pollard, Dike-induced faulting in rift zones of Iceland and Afar, Geology, 16, 413-417, 1988.
210. Rubin, K. H., and J. D. Macdougall, “‘Ra excesses in mid-ocean ridge basalts and mantie melting, Nature, 335, 158-161, 1988.
211. Rubin, K. H., and J. D. Macdougall, Dating of neovolcanic MORB using (226Ra/1>0Th) disequilibrium, Earth Planet. Sci. Lett., 101, 313-322, 1990.
212. 210Pb dating of recent volcanic eruptions on the seafloor, Nature, 368, 841-844, 1994.
213. Rubin, K. H., M. C. Smith, M. R. Perfit, D. M. Christie, and L. F. Sacks, Geochronology and petrology of lavas from the 1996 North Gorda Ridge eruption, Deep-Sea Res., in press.
214. Ruegg, J. C., J. C. Lepine, A. Tarantola, and M. Kasser, Geodetic measurements of rifting associated with a seismo-volcanic crisis in Afar, Geophys. Res. Lett., 6, 817-820, 1979.
215. Scheirer, D. S., and K. C. Macdonald, Variation in cross-sectional area of the axial ridge along the East Pacific Rise: Evidence for the magmatic budget of a fast spreading center, J. Geophys. Res., 98, 7871-7885, 1993.
216. Scheirer, D. S., and K. C. Macdonald, Near-axis seamounts on the flanks of the East Pacific Rise, 8°N to 17°N, J. Geophys. Res., 100, 2239-2259, 1995.
217. Scheirer, D. S., K. C. Macdonald, D. W. Forsyth, and Y. Shen, Abundant seamounts of the Rano Rahi field near the southem East Pacific Rise, 15aS to 19°S, Mar. Geophys. Res., 18, 13-52, 1996.
218. Schilling, J.-G., R. H. Kingsley, and J. D. Devine, Galapagos hot spot-spreading center system, 1, Spaţial, petrological and geochemical variations (83°W-101°W), J. Geophys. Res., 87, 5593-5610, 1982.
219. Schilling, J.-G., M. Zajac, R. Evans, T. Johnston, W. White, D. Devine, and R. Kingsley, Petrologie and geochemical variations along the Mid-Atlantic Ridge from 29°N to 73°N, Am. J. Sci., 283, 510-586, 1983.
220. Schreiner, A. E., C. G. Fox, and R. P. Dziak, Spectra and magnitudes of T-waves from the 1993 earthquake swann on the Juan de Fuca Ridge, Geophys. Res. Lett., 22, 139-142, 1995.
221. Scott, D. R., and D. J. Stevenson, A seif consistent model of melting, magma migration and bouyancy-driven circulation beneath mid-ocean ridges, J. Geophys. Res., 94, 2973-2988, 1989.
222. Sempéré, J. C., et al., The Southeast Indian Ridge between 88°E and 118°E: Variations in crustal accretion at constant spreading rate, J. Geophys. Res., 102, 15489-15505, 1997.
223. Sempéré, J. C., J. Lin, H. S. Brown, H. Schouten, and G. M. Purdy, Segmentation and morphotectonic variations along a slow-spreading center: The Mid-Atlantic Ridge (24°00’N-30°40'N), Mar. Geophys. Res., 15, 153-200, 1993.
224. Sempéré, J. C., G. M. Purdy, and H. Schouten, Segmentation of the Mid-Atlantic Ridge between 24°N and 30°40'N, Nature, 344, 427-431, 1990.
225. Sempéré, J. C., B. P. West, and L. Géli, The Southeast Indian Ridge between 127° and 132°40'E: Contrasts in segmentation characteristics and implications for crustal accretion, in Tectonic, Magmatic, Hydrothermal and Biological Segmentation of Mid-Ocean Ridges, Spec. Pub. 118, edited by C. J. MacLead, P. Tyler, and C. L. Walker, pp. 1-15, Geological Society of London, 1996.
226. Shen, Y., and D. W. Forsyth, Geochemical constraints on iniţial and final depths of melting beneath mid-ocean ridges, J. Geophys. Res., 100, 2211-2237, 1995.
227. Shen, Y., D. W. Forsyth, D. S. Scheirer, and K. C. Macdonald, Two fonns of volcanism: Implications for mantie flow and off-axis crustal production on the west flank of the southem East Pacific Rise, J. Geophys. Res., 98, 17875-17889, 1993.
228. Shen, Y., D. S. Scheirer, D. W. Forsyth, and K. C. Macdonald, Trade-off in production between adjacent seamount chains near the East Pacific Rise, Nature, 373, 140-143, 1995.
229. Sigurdsson, O., Surface deformation of the Krafla fissure swarm in two rifting events, J. Geophys., 47, 154-159, 1980.
230. Sims, K. W. W., D. J. DePaolo, M. T. Murrell, W. S. Baldridge, S.J. Goldstein, and D. A. Clague, Mechanisms of magma generation beneath Hawaii and mid-ocean ridges: U/Th and Sm/Nd isotopic evidence, Science, 267, 508-512, 1995.
231. Sims, K. W. W., S. J. Goldstein, D. J. Fomari, M. R. Perfit, M. T. Murrell, and S. R. Hart, U-series analyses of young lavas from 9°-10° N East Pacific Rise: Constraints on magma transport and storage times beneath the ridge axis, Eos Trans. Am. Geophys. Union, 78, F792, 1997a.
232. Sims, K. W. W., S. J. Goldstein, M. R. Perfit, D. J. Fomari, S. R. Hart, M. T. Murrell, and M. C. Smith, Spaţial and temporal variations in mid-ocean ridge basalt geochemistry along the East Pacific Rise: U-series disequilibria, radiogenic isotopes and elemental variability in a closely spaced, two-dimensional grid of samples from 9°48’-52’N., in Seventh Annual Goldschmidt Conf., LPI921, pp. 194, Lunar and Planetary Institute, Houston, Texas, 1997b.
233. Sinton, J. M., and R. S. Detrick, Mid-ocean ridge magma chambers, J. Geophys. Res., 97, 197-216, 1992.
234. Sinton, J. M., D. S. Wilson, D. M. Christie, R. N. Hey, and J. R. Delaney, Petrologie consequences of rift propagation on oceanic spreading ridges, Earth Planet. Sci. Let., 62, 193-207, 1983.
235. Sinton, J. S., S. M. Smaglik, J. J. Mahoney, and K. C. Macdonald, Magmatic processes at superfast spreading mid-ocean ridges: Glass compositional variations along the East Pacific Rise, 13°-23°S, J. Geophys. Res., 96, 6133-6155, 1991.
236. Sleep, N. H., Tapping of melt by veins and dikes, J. Geophys. Res., 93, 10,255-10,272, 1988.
237. Smith, D. K., and J. R. Cann, Hundreds of small volcanoes on the median valley floor of the Mid-Atlantic Ridge at 24-30°N, Nature, 348, 152-155, 1990.
238. Smith, D. K., and J. R. Cann, The role of seamount volcanism in crustal construction at the Mid-Atlantic Ridge (24°-30°N), J. Geophys. Res., 97, 1645-1658, 1992.
239. Smith, D. K., and J. R. Cann, Building the crust at the Mid-Atlantic Ridge, Nature, 365, 707-715, 1993.
240. Smith, D. K., et al., Mid-Atlantic Ridge volcanism from deep-towed side-scan sonar images, 25°-29°N, J. Volcanol. Geotherm. Res., 67, 233-262, 1995a.
241. Smith, M. C., M. R. Perfit, and A. L. Heatherington, High-resolution petrochemical mapping of individual eastern Pacific lava flows: Variances and genetic fingerprints, Eos Trans. Am. Geophys. Union, 77, F706, 1996.
242. Smith, M. C., M. R. Perfit, A. L. Heatherington, I. R. Jonasson, W. I. Ridley, R. W. Embley, and W. W. Chadwick, Elemental and isotopic constraints on the recent spaţial and temporal variations in MORB: CoAxial Segment, Juan de Fuca Ridge, Eos Trans. Am. Geophys. Union, 76, F410, 1995b.
243. Smith, M. C., M. R. Perfit, and I. R. Jonasson, Petrology and geochemistry of basalts from the southem Juan de Fuca Ridge: Controls on the spaţial and temporal evolution of mid-ocean ridge basalt, J. Geophys. Res., 99, 4787-4812, 1994.
244. Smith, M. C., M. R. Perfit, I. R. Jonasson, and W. I. Ridley, Preliminary petrologie investigations of the new eruption on the CoAxial segment of the Juan de Fuca Ridge, EOS Trans. Am. Geophys. Union, 74, 43, Fall Meeting suppl., 620, 1993.
245. Solomon, S. C., P. Y. Huang, and L. Meinke, The seismic moment budget of slow spreading ridges, Nature, 334, 58-60, 1988.
246. Stakes, D. S., J. W. Shervais, and C. A. Hopson, The volcanic-tectonic cycle of the FAMOUS and AMAR valleys, Mid-Atlantic Ridge (36S47'N): Evidence from basalt glass and phenocryst compositional variations for a steady state magma chamber beneath the valley midsections, AMAR 3, J. Geophys. Res., 89, 6995-7028, 1984.
247. Swanson, D. A., Pahoehoe flows from the 1969-1971 Mauna Ulu eruption, Kilauea volcano. Hawaii, Geol Soc. Am. Bull., 84, 615-626, 1973.
248. Sykes, L. R., Mechanisms of earthquakes and nature of faulting on the mid-ocean ridges, J. Geophys. Res., 72, 2131-2153, 1967.
249. Sykes, L. R., Earthquake swanns and seafloor spreading, J. Geophys. Res., 75, 6598-6611, 1970.
250. Takahashi, T. J., and J. D. Griggs, Hawaiian volcanic features: A photoglossary, in Volcanism in Hawaii, U.S. Geol. Surv. Prof. Pap., 1350, edited by R. W. Decker, T. L. Wright, and P. H. Stauffer, pp. 845-902, 1987.
251. Thompson, G., W. B. Bryan, R. Ballard, K. Hamuro, and W. G. Melson, Axial processes along a segment of the East Pacific Rise, 10-12°N, Nature, 318, 429-433, 1985.
252. Thompson, G., W. B. Bryan, and S. E. Humphris, Axial volcanism on the East Pacific Rise, 10-12°N, in Magmatism in the Ocean Basins, Geological Soc. Spec. Pub. 42, edited by A. D. Saunders, and M. J. Norry, pp. 181-200, 1989.
253. Tolstoy, M., A. J. Harding, and J. A. Orcutt, Crustal thickness on the Mid-Atlantic Ridge: Bull's-eye gravity anomalies and focused accretion, Science, 262, 726-729, 1993.
254. Toomey, D. R., S. C. Solomon, and G. M. Purdy, Tomographic imaging of the shallow crustal structure of the East Pacific Rise at 9°30’N, J. Geophys. Res., 99, 24,135-24,157, 1994.
255. Tryggvason, E., Widening of the Krafla fissure swarm during the 1975-1981 volcano-tectonic episode, Bull. Volcanol., 47, 47-69, 1984.
256. Tumer, R. J. W., D. E. Ames, J. M. Franklin, W. D. Goodfellow, C. H. B. Leitch, and T. Hfiy, Character of active hydrothennal mounds and nearby altered hemipelagic sediments in the hydrothennal areas of Middle Valley, northem Juan de Fuca Ridge: Data on shallow cores, Can. Mineral., 31, 973-995, 1993.
257. Urabe, T., et al., The effect of magmatic activity on hydrothermal venting along the superfast-spreading East Pacific Rise, Science, 269, 1092-1095, 1995.
258. Van Andel, T. H., and R. D. Ballard, The Galapagos rift at 86°W: 2. Volcanism, structure, and evolution of the rift valley, J. Geophys. Res., 84, 5390-5406, 1979.
259. Vera, E. E., and J. B. Diebold, Seismic imaging of oceanic layer 2A between 9°30'N and 10°N on the East Pacific Rise from two-ship wide-aperture profiles, J. Geophys. Res., 99, 3031-3041, 1994.
260. Volpe, A. M., and S. J. Goldstein, i“Ra-230Th disequilibrium in axial and off-axis mid-ocean ridge basalts, Geochim. Cosmochim. Acta, 57, 1233-1242, 1993.
261. Weaver, J. S., and C. H. Langmuir, Calculations of phase equilibrium in mineral-melt systems, Computers and Geosciences, 16, 1-19, 1990.
262. Wentworth, C. K., and G. A. Macdonald, Structures and forms of bas al tic rocks in Hawaii, U.S. Geol. Surv. Bull. 994, 95 pp., 1953.
263. White, S. M., K. C. Macdonald, D. S. Scheirer, M. H. Cormier, and R. M. Haymon, Near-axis volcanism at the SEPR: Is the neovolcanic zone 28 kilometers wide?, EOS Trans. Am. Geophys. Union, 78, 46, Fall Meeting suppl., F689, 1997.
264. Wolfe, E. W., M. O. Garcia, D. B. Jackson, R. Y. Koyanagi, C. A. Neal, and A. T. Okamura, The Puu Oo eruption of Kilauea volcano, episodes 1-20, January 3, 1983, to June 8, 1984, in Volcanism in Hawaii, U.S. GeoL Surv. Prof. Pap. 1350, edited by R. W. Decker, T. L. Wright, and P. H. Stauffer, pp. 471-508, 1987.
265. Wright, D. J., R. M. Haymon, and D. J. Fomari, Crustal fissuring and its relationship to magmatic and hydrothermal processes on the East Pacific Rise crest (9* 12' to 54'N), J. Geophys. Res., 100, 6097-6120, 1995.
266. Zierenberg, R. A., R. A. Koški, J. L. Morton, R. M. Bouse, and W. C. Shanks, Genesis of massive sulfide deposits on a sediment-covered spreading center, Escanaba Trough, southem Gorda Ridge, Econ. Geol., 88, 2069-2098, 1993.
267. Zierenberg, R. A., J. L. Morton, R. A. Koski, and S. L. Ross, Geologic setting of massive sulfide mineralization in Escanaba Trough, in Geologic, Hydrothermal, tmd Biologic Studies at Escanaba Trough, Gorda Ridge, Offshore Northern California, U.S. Geol Surv. Bull. 2022, edited by J. L. Morton, R. A. Zierenberg, and C. A. Reiss, pp. 171-197, 1994.
268. Zonenshain, L. P., M. I. Kazmin, A. P. Lisitsin, Y. A. Bogdanov, and B. V. Baranov, Tectonics of tbe Mid-Atlantic rift valley between the TAG and MARK areas (26-24°N): Evidence for vertical tectonism, Tectonophysics, 159, 1-23, 1989.