Bainbridge, A., Crane, K., and van Andel, T. H., 1979. Submarine thermal springs on the Galapagos Rift. Science, 203,
1073–1083.
Delaney, J. R., Robigou, V., McDuff, R. E., and Tivey, M. K., 1992.
Geology of a vigorous hydrothermal system on the Endeavour
Segment, Juan de Fuca Ridge. Journal of Geophysical Research,
97, 19663–19682.
Fouquet, Y., Wafik, A., Cambon, P., Mevel, C., Meyer, G., and
Gente, P., 1993. Tectonic setting, mineralogical and geochemical
zonation in the Snake Pit sulfide deposit (Mid-Atlantic Ridge at
23
N). Economic Geology, 88, 2018–2036.
Francheteau, J., Needham, H. D., Choukroune, P., Juteau, T.,
Seguret, M., Ballard, R. D., Fox, P. J., Normark, W., Carranza,
A., Cordoba, D., Guerrero, J., Rangin, C., Bougault, H.,
Cambon, P., and Hekinian, R., 1979. Massive deep-sea sulphide
ore deposits discovered on the East Pacific Rise. Nature, 277,
523–528.
German, C., and Von Damm, K., 2006. Hydrothermal processes. In
Holland, H. D., and Turekian, K. K. (eds.), Treatise on Geochemistry, volume 6: The Oceans and Marine Chemistry. London: Elsevier, pp. 181–222.
Goldfarb, M. S., Converse, D. R., Holland, H. D., and Edmond,
J. M., 1983. The genesis of hot spring deposits on the East
Pacific Rise, 21N. In Ohmoto, H., and Skinner, B. J. (eds.),
The Kuroko and Related Volcanogenic Massive Sulfide Deposits.
New Haven, Conn: Economic Geology Publication. Economic
Geology Monograph, Vol. 5, pp. 184–197.
Hannington, M. D., and Scott, S. D., 1988. Mineralogy and geochemistry of a hydrothermal silica- sulfide-sulfate spire in the
caldera of Axial Seamount, Juan de Fuca Ridge. Canadian Mineralogist, 26, 603–625.
Haymon, R. M., 1983. Growth history of hydrothermal black
smoker chimneys. Nature, 301, 695–698.
Haymon, R. M., and Kastner, M., 1981. Hot spring deposits on the
East Pacific Rise at 21
N: preliminary description of mineralogy
and genesis. Earth and Planetary Science Letters, 53, 363–381.
Jannasch, H., 1995. Microbial interactions with hydrothermal
fluids. In Humphris, S. E., Zierenberg, R. A., Mullineaux,
L. S., and Thomson, R. E. (eds.), Seafloor Hydrothermal Systems. Washington, DC: American Geophysical Union. American
Geophysical Union Monograph, Vol. 91, pp. 273–296.
Juniper, S. K., Jonasson, I. R., Tunnicliffe, V., and Southward, A. J.,
1992. Influence of a tube-building polychaete on hydrothermal
chimney mineralization. Geology, 20, 895–898.
Kelley, D. S., Karson, J. A., Fruh-Green, G. L., Yoerger, D. R.,
Shank, T. M., Butterfield, D. A., Hayes, J. M., Schrenk, M. O.,
Olsen, E. J., Proskurowski, G., Jakuba, M., Bradley, A., Larson,
B., Ludwig, K., Glickson, D., Buckman, K., Bradley, A. S.,
Brazelton, W. J., Roe, K., Elend, M. J., Delacour, A.,
Bernasconi, S. M., Lilley, M. D., Baross, J. A., Summons,
R. E., and Sylva, S. P., 2005. A serpentinite-hosted ecosystem:
the Lost City hydrothermal field. Science, 307, 1428–1434.
Koski, R. A., Jonasson, I. R., Kadko, D. C., Smith, V. K., and Wong,
F. L., 1994. Compositions, growth mechanisms, and temporal
relations of hydrothermal sulfide-sulfate-silica chimneys at the
northern Cleft segment, Juan de Fuca Ridge. Journal of Geophysical Research, 99, 4813–4832.
Spiess, F. N., Macdonald, K. C., Atwater, T., Ballard, R., Carranza,
A., Cordoba, D., Cox, C., Diaz Garcia, V. M., Francheteau, J.,
Guerrero, J., Hawkins, J., Haymon, R., Hessler, R., Juteau, T.,
Kastner, M., Larson, R., Luyendyk, B., Macdougall, J. D.,
Miller, S., Normark, W., Orcutt, J., and Rangin, C., 1980. East
pacific rise: hot-springs and geophysical experiments. Science,
207, 1421–1433.
Styrt, M. M., Brackman, A. J., Holland, H. D., Clark, B. C., PisuthaArnold, V., Eldridge, C. S., and Ohmoto, H., 1981. The mineralogy and the isotopic composition of sulfur in hydrothermal
sulfide/sulfate deposits on the East Pacific Rise, 21
N latitude.
Earth and Planetary Science Letters, 53, 382–390.
Tivey, M. K., 1998. How to build a black smoker chimney: the
formation of mineral deposits at mid-ocean ridges. Oceanus,
41, 68–74.
Cross-references
Chemosynthetic Life
Hydrothermal Plumes
Hydrothermal Vent Fluids (Seafloor)
Hydrothermalism
Marine Heat Flow
Marine Mineral Resources
Marginal Seas
Oceanic Spreading Centers
Peridotites
Volcanogenic Massive Sulfides
BOTTOM SIMULATING SEISMIC REFLECTORS (BSR)
Jürgen Mienert and Stefan Bünz
Centre for Arctic Gas Hydrate, Environment and
Climate (CAGE), UiT The Arctic University of Norway,
Tromsø, Norway
Definition
A seismic reflection occurring in the upper few hundred
meters of marine sediments mimicking the seafloor, crosscutting sediment layers, and showing a phase reversal is
known as a “bottom-simulating reflector.” Such a gas
hydrate-related BSR originates from a large impedance
contrast between a layer of gas-hydrated sediment above
and a free gas layer below. A diagenetic-related BSR
occurs at the opal-A/opal-CT transition zone, lies often
deep and outside the base of the gas hydrate stability zone,
shows no phase reversal, and does not always mimic the
seafloor.
Introduction
The intent of this article is to describe the two most commonly observed bottom-simulating reflectors (BSRs).
The term BSR stems from their principal characteristic
that these reflectors mimic the seafloor topography in
marine seismic reflection data thereby crosscutting sedimentary strata. BSRs are known to occur in continental
margin sediments in regions of gas hydrate and free gas
(Shipley et al., 1979) and/or in siliceous ooze (diatoms,
radiolaria, silica sponges, silicoflagellates) bearing sedimentary formations (Hein et al., 1978). The largest silica
contribution comes from diatoms (Holland and Turekian,
2003), while the largest methane contribution derives
from methane-producing Archaea in sub-seafloor sediments (e.g., Kotelnikova, 2002).
62
BOTTOM SIMULATING SEISMIC REFLECTORS (BSR)
1073–1083.
Delaney, J. R., Robigou, V., McDuff, R. E., and Tivey, M. K., 1992.
Geology of a vigorous hydrothermal system on the Endeavour
Segment, Juan de Fuca Ridge. Journal of Geophysical Research,
97, 19663–19682.
Fouquet, Y., Wafik, A., Cambon, P., Mevel, C., Meyer, G., and
Gente, P., 1993. Tectonic setting, mineralogical and geochemical
zonation in the Snake Pit sulfide deposit (Mid-Atlantic Ridge at
23
N). Economic Geology, 88, 2018–2036.
Francheteau, J., Needham, H. D., Choukroune, P., Juteau, T.,
Seguret, M., Ballard, R. D., Fox, P. J., Normark, W., Carranza,
A., Cordoba, D., Guerrero, J., Rangin, C., Bougault, H.,
Cambon, P., and Hekinian, R., 1979. Massive deep-sea sulphide
ore deposits discovered on the East Pacific Rise. Nature, 277,
523–528.
German, C., and Von Damm, K., 2006. Hydrothermal processes. In
Holland, H. D., and Turekian, K. K. (eds.), Treatise on Geochemistry, volume 6: The Oceans and Marine Chemistry. London: Elsevier, pp. 181–222.
Goldfarb, M. S., Converse, D. R., Holland, H. D., and Edmond,
J. M., 1983. The genesis of hot spring deposits on the East
Pacific Rise, 21N. In Ohmoto, H., and Skinner, B. J. (eds.),
The Kuroko and Related Volcanogenic Massive Sulfide Deposits.
New Haven, Conn: Economic Geology Publication. Economic
Geology Monograph, Vol. 5, pp. 184–197.
Hannington, M. D., and Scott, S. D., 1988. Mineralogy and geochemistry of a hydrothermal silica- sulfide-sulfate spire in the
caldera of Axial Seamount, Juan de Fuca Ridge. Canadian Mineralogist, 26, 603–625.
Haymon, R. M., 1983. Growth history of hydrothermal black
smoker chimneys. Nature, 301, 695–698.
Haymon, R. M., and Kastner, M., 1981. Hot spring deposits on the
East Pacific Rise at 21
N: preliminary description of mineralogy
and genesis. Earth and Planetary Science Letters, 53, 363–381.
Jannasch, H., 1995. Microbial interactions with hydrothermal
fluids. In Humphris, S. E., Zierenberg, R. A., Mullineaux,
L. S., and Thomson, R. E. (eds.), Seafloor Hydrothermal Systems. Washington, DC: American Geophysical Union. American
Geophysical Union Monograph, Vol. 91, pp. 273–296.
Juniper, S. K., Jonasson, I. R., Tunnicliffe, V., and Southward, A. J.,
1992. Influence of a tube-building polychaete on hydrothermal
chimney mineralization. Geology, 20, 895–898.
Kelley, D. S., Karson, J. A., Fruh-Green, G. L., Yoerger, D. R.,
Shank, T. M., Butterfield, D. A., Hayes, J. M., Schrenk, M. O.,
Olsen, E. J., Proskurowski, G., Jakuba, M., Bradley, A., Larson,
B., Ludwig, K., Glickson, D., Buckman, K., Bradley, A. S.,
Brazelton, W. J., Roe, K., Elend, M. J., Delacour, A.,
Bernasconi, S. M., Lilley, M. D., Baross, J. A., Summons,
R. E., and Sylva, S. P., 2005. A serpentinite-hosted ecosystem:
the Lost City hydrothermal field. Science, 307, 1428–1434.
Koski, R. A., Jonasson, I. R., Kadko, D. C., Smith, V. K., and Wong,
F. L., 1994. Compositions, growth mechanisms, and temporal
relations of hydrothermal sulfide-sulfate-silica chimneys at the
northern Cleft segment, Juan de Fuca Ridge. Journal of Geophysical Research, 99, 4813–4832.
Spiess, F. N., Macdonald, K. C., Atwater, T., Ballard, R., Carranza,
A., Cordoba, D., Cox, C., Diaz Garcia, V. M., Francheteau, J.,
Guerrero, J., Hawkins, J., Haymon, R., Hessler, R., Juteau, T.,
Kastner, M., Larson, R., Luyendyk, B., Macdougall, J. D.,
Miller, S., Normark, W., Orcutt, J., and Rangin, C., 1980. East
pacific rise: hot-springs and geophysical experiments. Science,
207, 1421–1433.
Styrt, M. M., Brackman, A. J., Holland, H. D., Clark, B. C., PisuthaArnold, V., Eldridge, C. S., and Ohmoto, H., 1981. The mineralogy and the isotopic composition of sulfur in hydrothermal
sulfide/sulfate deposits on the East Pacific Rise, 21
N latitude.
Earth and Planetary Science Letters, 53, 382–390.
Tivey, M. K., 1998. How to build a black smoker chimney: the
formation of mineral deposits at mid-ocean ridges. Oceanus,
41, 68–74.
Cross-references
Chemosynthetic Life
Hydrothermal Plumes
Hydrothermal Vent Fluids (Seafloor)
Hydrothermalism
Marine Heat Flow
Marine Mineral Resources
Marginal Seas
Oceanic Spreading Centers
Peridotites
Volcanogenic Massive Sulfides
BOTTOM SIMULATING SEISMIC REFLECTORS (BSR)
Jürgen Mienert and Stefan Bünz
Centre for Arctic Gas Hydrate, Environment and
Climate (CAGE), UiT The Arctic University of Norway,
Tromsø, Norway
Definition
A seismic reflection occurring in the upper few hundred
meters of marine sediments mimicking the seafloor, crosscutting sediment layers, and showing a phase reversal is
known as a “bottom-simulating reflector.” Such a gas
hydrate-related BSR originates from a large impedance
contrast between a layer of gas-hydrated sediment above
and a free gas layer below. A diagenetic-related BSR
occurs at the opal-A/opal-CT transition zone, lies often
deep and outside the base of the gas hydrate stability zone,
shows no phase reversal, and does not always mimic the
seafloor.
Introduction
The intent of this article is to describe the two most commonly observed bottom-simulating reflectors (BSRs).
The term BSR stems from their principal characteristic
that these reflectors mimic the seafloor topography in
marine seismic reflection data thereby crosscutting sedimentary strata. BSRs are known to occur in continental
margin sediments in regions of gas hydrate and free gas
(Shipley et al., 1979) and/or in siliceous ooze (diatoms,
radiolaria, silica sponges, silicoflagellates) bearing sedimentary formations (Hein et al., 1978). The largest silica
contribution comes from diatoms (Holland and Turekian,
2003), while the largest methane contribution derives
from methane-producing Archaea in sub-seafloor sediments (e.g., Kotelnikova, 2002).
62
BOTTOM SIMULATING SEISMIC REFLECTORS (BSR)