Lateral continuity of basement seismic reflections in 15 Ma ultrafast-spreading crust at ODP Site 1256
MetadataShow full item record
The Ocean Drilling Program (ODP) initiated drilling at Site 1256D in the Guatemala Basin, about 1000km off the East Pacific Rise to penetrate plutonic rocks, anticipated to be relatively shallow in this region, formed at an ultra-fast spreading rate. IODP Expedition E312 successfully drilled into gabbros at ~ 1150m in basement. Multi-channel seismic traces show weak laterally coherent sub-basement reflections at borehole depths. Synthetic reflectivity seismograms were computed using a Ricker wavelet and impedance profiles from borehole sonic logs. These seismograms show significant sub-basement amplitude peaks. A zero-offset vertical seismic profile, shot on E312, was processed to investigate the authenticity of these reflections and their relationship to borehole geology. A dual scheme of the median filtering and F-K dip filtering was used. Tests with synthetic seismograms indicate the approach is effective at reasonable SNR levels. Downgoing energy is clearly identified but negligible upgoing energy is visible over random noise. These results indicate that lava flows and igneous contacts in upper ocean crust have significant topography on lateral scales less than the Fresnel Zone (~ 300m) due to igneous and tectonic processes.
Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Marine Geophysical Research 32 (2011): 429-439, doi:10.1007/s11001-011-9122-4.
Showing items related by title, author, creator and subject.
Relationships among seismic velocity, metamorphism, and seismic and aseismic fault slip in the Salton Sea Geothermal Field region McGuire, Jeffrey J.; Lohman, Rowena B.; Catchings, Rufus D.; Rymer, Michael J.; Goldman, Mark R. (John Wiley & Sons, 2015-04-28)The Salton Sea Geothermal Field is one of the most geothermally and seismically active areas in California and presents an opportunity to study the effect of high-temperature metamorphism on the properties of seismogenic ...
Seismic structure of the Endeavour Segment, Juan de Fuca Ridge : correlations with seismicity and hydrothermal activity Van Ark, Emily M.; Detrick, Robert S.; Canales, J. Pablo; Carbotte, Suzanne M.; Harding, Alistair J.; Kent, Graham M.; Nedimovic, Mladen R.; Wilcock, William S. D.; Diebold, John B.; Babcock, Jeffrey M. (American Geophysical Union, 2007-02-03)Multichannel seismic reflection data collected in July 2002 at the Endeavour Segment, Juan de Fuca Ridge, show a midcrustal reflector underlying all of the known high-temperature hydrothermal vent fields in this area. On ...
Trehu, Anne M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1982-02)In this thesis, seismic waves generated by sources ranging from 2.7 kg shots of TNT to magnitude 5 earthquakes are studied in order to determine the seismic activity and crustal structure of the Orozco transform fault. ...