Oceanic Lithosphere-3

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<ul><li> 1. Solid Earth GeophysicsAli Oncel [email_address] Department of Earth Sciences KFUPM Todays class:Oceanic Lithosphere Reading: Fowler Chapter 9 , pp.391-416</li></ul> <p> 2. </p> <ul><li><ul><li>Oceanic Crust and Continental Crust </li></ul></li></ul> <ul><li><ul><li>Total Sediment Thickness Database </li></ul></li></ul> <ul><li><ul><li>Depth of Sea Floor versus Age of Sea Floor </li></ul></li></ul> <ul><li><ul><li>Marine Seismic Acquisition </li></ul></li></ul> <ul><li><ul><li>OBS and Streamer </li></ul></li></ul> <p>SummaryLecture 12 3. Chapter Exam Next Tuesday Class Fowler Chapters 8 and9 , pp.391-416 Assignment Prepare your questions for Chapter 9n and upload them to class page before the exam. April 21, 2007 4. Exposed Oceanic Crust</p> <ul><li>Often regarded as examples of oceanic crust.However, because they are now tectonically emplaced on land, they are atypical and might not represent n normal oceanic crust.Ophiolites are probably samples of young oceanic crust produced in back-arc basins, or fore-arc basins, associated with subduction zones (Fowler, pp.405). </li></ul> <p>Oman ophiolite harzburgite upper mantle both from: http://www.bris.ac.uk/Depts/Geol/vft/oman.html 5. pp. 339 of Stein, 2003 modified after McClousky et al., 2000 6. Why does the Ocean Depth with lithospheric age deepens with distance from the spreading ridges? Recall 7. Depth forOcean Age forLithosphere If a body cools, what happens to its density? 8. 9. 10. MULTICHANNEL SEISMICEQUIPMENT P.Farcy Farcy, B. , B. Marsset Marsset, H. , H. Nouze Nouze 11. 12. Ocean Bottom Seismograph http://www.geopro.com/obs.html The OBS is cased in a glass sphere which can be deployed up to water depths of 6700m, recording seismic signals directly on the seafloor with a gimbal mounted 3C-geophone and a deep sea hydrophone. 13. http://www.geopro.com/obs.html 14. VSea =1525 m/s V sediments= 1800 m/s V Metamorphic=2500 m/s 15. Reflection signature of seismic and aseismic slip on the northern Cascadia subduction interface , Nedimovic et al., NATURE |VOL 42424 JULY 2003 16. Nedimovic et al.,NATURE |VOL 424 | 24 JULY 2003 | 17. 18. W ideA pertureR eflectionR efractionP rofiling 19. WARP Offshore </p> <ul><li>The basic principle of WARRP is utilizing the amplitude burst when P-wave energy is totally reflected beyond the critical angle of incidence. To record at wide angles large offsets are required, much larger than conventional seismic arrays can provide.</li></ul> <p> 20. OBS application with a vertical streamer http://www.geopro.com 21. 22. Deep Sea P Sensor 23. Deep-sea pressure sensors (Germany) 24. Suggested global distribution of deep sea pressure sensors (to be defined)</p>

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