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Scientists Study Earth's Missing Crust

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Author Topic: Scientists Study Earth's Missing Crust  (Read 195 times)
Brittany
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« on: April 14, 2007, 10:45:22 pm »

Geology & Geophysics Group
Iberia & Newfoundland margins
Contact: Dr Donna Shillington


The Iberia-Newfoundland conjugate margins constitute one of the best-studied nonvolcanic rifted margin systems in the world. Four Ocean Drilling Program (ODP) legs (103, 149, 173 and 210) and numerous geophysical studies have been dedicated to this rift system. Rifting of these margins was accompanied by very little synrift magmatism. As a result, key rifting structures are not obscured by synrift volcanic flows, making this margin pair an ideal natural laboratory in which to study the processes responsible for continental breakup and incipient seafloor spreading.




Drilling and geophysical studies of these margins have revealed that the late stages of rifting were partially accommodated by extension along detachment and/or rolling hinge faults and the exposure of subcontinental mantle at the seafloor. Many questions remain concerning the style of the early stages of rifting, the processes responsible for exposing subcontinental mantle, and how the transition from magma-starved rifting to initial seafloor spreading occurred. These topics are the motivation for additional proposed work on this margin system, including three Integrated Ocean Drilling Program (IODP) proposals.



Related publications

Chian, D., K. E. Louden, T. A. Minshull, and R. B. Whitmarsh, 1999, Deep structure of ocean-continent transition in the southern Iberia abyssal plain from seismic refraction profiles; Ocean Drilling Program (legs 149 and 173) transect: J. Geophys. Res., v. 104, p. 7443-7462.

Cole, P. B., T. A. Minshull, and R. B. Whitmarsh, 2002, Azimuthal seismic anisotropy in a zone of exhumed continental mantle, West Iberia margin: Geophys. J. Int., v. 151, p. 517-533.

Dean, S. M., T. A. Minshull, R. B. Whitmarsh, and K. E. Louden, 2000, Deep structure of the ocean-continent transition in the southern Iberia Abyssal Plain from seismic refraction profiles: The IAM-9 transect at 40o20'N: J. Geophys. Res., v. 105, p. 5859-5885.

Leythaeuser, T., T. J. Reston, and T. A. Minshull, 2005, Waveform inversion of the S reflector west of Spain: Fine structure of a detachment fault: Geophysical Research Letters, v. 32, Art No. L22304.

Minshull, T. A., 2002, The break-up of continents and the formation of new ocean basins: Phil. Trans. Royal Soc. London, v. 360, p. 2839-2852.

Manatschal,G., O. Müntener, L. Lavier, T. A. Minshull, and G. Peron-Pinvidic, Observations from the Alpine Tethys and Iberia/Newfoundland margins pertinent to the interpretation of continental break-up, in Extensional Deformation of the Lithosphere, Columbia University Press, in press.

Minshull, T. A., S. M. Dean, R. S. White, and R. B. Whitmarsh, 2001, Anomalous melt production after continental break-up in the southern Iberia Abyssal Plain, in R. C. L. Wilson, R. B. Whitmarsh, B. Taylor, and N. Froitzheim, eds., Non-Volcanic Rifting of Continental Margins: A Comparison of Evidence from Land and Sea, v. 187: London, Geological Society, p. 537-550.

Minshull, T. A., S. M. Dean, R. B. Whitmarsh, S. M. Russell, K. E. Louden, and D. Chian, 1998, Deep structure in the vicinity of the ocean-continent transition zone under the southern Iberia abyssal plain: Geology, v. 26, p. 743-746.

Pickup, S. L. B., R. B. Whitmarsh, C. M. R. Fowler, and T. J. Reston, 1996, Insight into the nature of the ocean-continent transition off West Iberia from a deep multichannel seismic reflection profile: Geology, v. 24, p. 1079-1082.

Pinheiro, L. M., R. B. Whitmarsh, and P. R. Miles, 1992, The ocean-continent boundary off the western continental margin of Iberia - II. Crustal structure in Tagus Abyssal Plain: Geophys. J. Int., v. 109, p. 106-124.

Russell, S. M., and R. B. Whitmarsh, 2003, Magmatism at the West Iberia non-volcanic rifted continental margin; evidence from analyses of magnetic anomalies: Geophys. J. Int., v. 154, p. 706-730.

Sawyer, D. S., R. B. Whitmarsh, A. Klaus, and e. al., 1994, Proc. ODP, Init. Repts, v. 149: College Station, TX, Ocean Drilling Program.

Shillington, D. J., W. S. Holbrook, B. E. Tucholke, J. R. Hopper, K. E. Louden, H. C. Larsen, H. J. A. Van Avendonk, S. Deemer, and H. J., 2004, Marine Geophysical Data on the Newfoundland Nonvolcanic Rifted Margin Around SCREECH Transect 2, in B. E. Tucholke, J.-C. Sibuet, and A. Klaus, eds., Proc. ODP, Init. Repts., v. 210: College Station, TX, Ocean Drilling Program, p. Available online at http://www-odp.tamu.edu/publications/210_IR/chap_05/chap_05.htm.

Shillington, D. J., W. S. Holbrook, H. J. A. Van Avendonk, B. E. Tucholke, J. R. Hopper, K. E. Louden, H. C. Larsen, G. T. Nunes, and O. L. S. S. Party, 2006, Evidence for asymmetric nonvolcanic rifting and slow incipient oceanic accretion from seismic reflection data on the Newfoundland margin: J. Geophys. Res., v. 111, p. doi:10.1029/2005JB003981.

Shillington, D. J., B. E. Tucholke, G. D. Karner, D. S. Sawyer, W. S. Holbrook, and H. Delius, in review, Linking core and seismic data without logs: Core-seismic correlation at Site 1276, in B. E. Tucholke, J.-C. Sibuet, and A. Klaus, eds., Proc. ODP Sci. Results, v. 210: College Station, TX, Ocean Drilling Program.

Tucholke, B. E., J.-C. Sibuet, A. Klaus, and et al., 2004, Proc. ODP, Init. Rept., v. 210: College Station, TX, Ocean Drilling Program.

Tucholke, B. E., and R. B. Whitmarsh, in press, The Newfoundland-Iberia conjugate rifted margins, in A. W. Bally, and D. G. Roberts, eds., Principles of Phanerozoic Regional Geology: Amsterdam, Elsevier.

Van Avendonk, H. J. A., W. S. Holbrook, G. T. Nunes, D. J. Shillington, B. E. Tucholke, K. E. Louden, H. C. Larsen, and J. R. Hopper, in press, Seismic velocity variations across the rifted margin of the eastern Grand Banks, Canada: J. Geophys. Res.

Peron-Pinvidic, G., G. Manatschal, S. M. Dean, and T. A. Minshull, Compressional structures on the West Iberia rifted margin: what controls their distribution? In: The Nature and Origin of Compression in Passive Margins, Geol. Soc. London Special Publication, London, Geological Society, submitted.

Peron-Pinvidic, G., G. Manatschal, T. A. Minshull, and D. Sawyer, The tectono-sedimentary and morpho-tectonic evolution recorded in the deep Iberia-Newfoundland margins: Evidence for a complex break-up history, Tectonics, submitted.

Whitmarsh, R. B., M.-O. Beslier, P. J. Wallace, and e. al., 1998, Proc. ODP Init. Rept., v. 173: College Station, TX, Ocean Drilling Program.

Whitmarsh, R. B., S. M. Dean, and T. A. Minshull, 2000, Tectonic Implications of exposure of lower continental curst beneath the Iberia Abyssal Plain, Northeast Atlantic Ocean: Geophysical evidence: Tectonics, v. 19, p. 919-942.

Whitmarsh, R. B., G. Manatschal, and T. A. Minshull, 2001a, Evolution of magma-poor continental margins from rifting to seafloor spreading: Nature, v. 413, p. 150-153.

Whitmarsh, R. B., and P. R. Miles, 1995, Models of the development of the West Iberia rifted continental margin at 40˚30'N deduced from surface and deep-tow magnetic anomalies: J. Geophys. Res., v. 100, p. 3789-3806.

Whitmarsh, R. B., P. R. Miles, and A. Mauffret, 1990, The ocean-continent boundary off the western continental margin of Iberia -- I. Crustal Structure at 40º30'N: Geophys. J. Int., v. 103, p. 509-531.

Whitmarsh, R. B., T. A. Minshull, S. M. Russell, S. M. Dean, K. E. Louden, and D. Chian, 2001b, The role of syn-rift magmatism in the rift-to-drift evolution of the West Iberia continental margin: geophysical observations, in R. C. L. Wilson, R. B. Whitmarsh, B. Taylor, and N. Froitzheim, eds., Non-volcanic Rifting of Continental Margins: A Comparison of Evidence from Land and Sea, v. 187: London, Geological Society, p. 107-124.

Whitmarsh, R. B., L. M. Pinheiro, P. R. Miles, M. Recq, and J.-C. Sibuet, 1993, Thin crust at the western Iberian ocean-continent transition and ophiolites: Tectonics, v. 12, p. 1230-1239.

Whitmarsh, R. B., R. S. White, S. J. Horsefield, J.-C. Sibuet, M. Recq, and V. Louvel, 1996, The ocean-continent boundary off the western continental margin of Iberia: Crustal structure west of Galicia Bank: J. Geophys. Res., v. 101, p. 28,291-28,314.

http://www.noc.soton.ac.uk/gg/research/rifts/newfoundland.php
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