Geophysical Constraints on Mechanisms of Ocean Plateau Formation from Shatsky Rise, Northwest Pacific Cruise Report MGL1004 R/V Marcus G. Langseth Honolulu to Honolulu 17 July – 13 September, 2010 Jun Korenaga William Sager Department of Geology and Geophysics Department of Oceanography Yale University Texas A&M University New Haven, CT 06520 College Station, TX, 77843 Table of Contents SUMMARY ...............................................................................................................................................................4 EXECUTIVE SUMMARY ...............................................................................................................................................4 SCIENTIFIC OBJECTIVES ............................................................................................................................................5 OPERATIONAL OBJECTIVES.......................................................................................................................................6 PRELIMINARY CRUISE ASSESSMENT.........................................................................................................................7 PROJECT PRINCIPAL INVESTIGATORS ..........................................................................................................9 PERSONNEL ......................................................................................................................................................... 10 SCIENCE COMPLEMENT........................................................................................................................................... 10 R/V MARCUS G. LANGSETH CREW........................................................................................................................ 11 NARRATIVE ......................................................................................................................................................... 12 INTRODUCTION AND BACKGROUND .......................................................................................................... 22 SCIENTIFIC BACKGROUND: OCEANIC PLATEAU FORMATION............................................................................... 22 ORIGIN OF SHATSKY RISE ...................................................................................................................................... 24 WHY STUDY SHATSKY RISE?................................................................................................................................. 25 TESTING PLUME AND RIDGE MODELS................................................................................................................... 26 PRIOR RESEARCH ON SHATSKY RISE .................................................................................................................... 28 INITIAL SURVEY PLAN ..................................................................................................................................... 30 OPERATION DETAILS....................................................................................................................................... 32 NAVIGATION ........................................................................................................................................................... 32 SEISMIC REFRACTION SHOOTING OPERATIONS ................................................................................................... 33 MULTICHANNEL SEISMIC SHOOTING OPERATIONS .............................................................................................. 33 OCEAN BOTTOM SEISMOMETER OPERATIONS ..................................................................................................... 35 WHOI D2 – DEPLOYMENT........................................................................................................................................................35 WHOI D2 – RECOVERY..............................................................................................................................................................36 UNDERWAY GEOPHYSICS ....................................................................................................................................... 37 MULTIBEAM BATHYMETRY........................................................................................................................................................37 TOWED MAGNETOMETER ...........................................................................................................................................................37 GRAVIMETER.................................................................................................................................................................................37 FLUXGATE MAGNETOMETER......................................................................................................................................................37 WEATHER INFORMATION ...................................................................................................................................... 38 SHIPBOARD COMPUTING ENVIRONMENT.............................................................................................................. 39 SHIPBOARD DATA PROCESSING ............................................................................................................................ 39 MULTICHANNEL SEISMIC PROFILES.........................................................................................................................................39 MULTIBEAM BATHYMETRY........................................................................................................................................................41 INITIAL OCEAN BOTTOM SEISMOMETER DATA PROCESSING..............................................................................................42 OCEAN BOTTOM SEISMOMETER SEGY DATA PROCESSING.................................................................................................42 SURVEY OUTCOME AND ASSESSMENT ....................................................................................................... 44 2 PRELIMINARY DATA REVIEW ....................................................................................................................... 48 MULTICHANNEL SEISMIC PROFILES ...................................................................................................................... 48 OCEAN BOTTOM SEISMOMETER DATA ................................................................................................................. 60 MULTIBEAM BATHYMETRY ................................................................................................................................... 62 UNDERWAY GEOPHYSICAL DATA .......................................................................................................................... 67 REFERENCES ....................................................................................................................................................... 69 APPENDICES........................................................................................................................................................ 73 DATA LIST............................................................................................................................................................... 73 MCS LOGS............................................................................................................................................................... 74 MCS PROCESSING PARAMETERS OUTLINE ........................................................................................................... 74 LITTLE SCRIPTS FOR MCS PROCESSING................................................................................................................ 79 PYTHON SCRIPT FOR P190 FILES: P190_SHOT_DIST_XEND.PY..........................................................................................79 GMT SCRIPT FOR PLOTTING BLACK WHITE SEISMIC SECTIONS: PLOTSEGY.GMT .............................................................80 GMT SCRIPT FOR PLOTTING COLOR SEISMIC SECTIONS: SEGY2GRD.GMT .........................................................................81 WHOI D2 SEISMIC RECEIVER INSTRUMENT DESCRIPTION ................................................................................ 82 OCEAN BOTTOM SEISMOMETER DEPLOYMENT RECORD..................................................................................... 84 OCEAN BOTTOM SEISMOMETER RECOVERY RECORD ........................................................................................... 85 OCEAN BOTTOM SEISMOMETER DATA QUALITY ................................................................................................. 86 WEEKLY REPORTS TO NSF.................................................................................................................................... 87 NOTES ON OUTREACH EFFORTS ..........................................................................................................................100 SUMMARY OF PRE-CRUISE TWISTS AND TURNS.................................................................................................101 INCIDENTAL HARASSMENT AUTHORIZATION (IHA) .........................................................................................102 3 Summary Executive Summary R/V Marcus G. Langseth cruise MGL1004 formed the major data acquisition phase of the