PACIFIC ENEWETAK ATOLL CRATER EXPLORATION (PEACE) PROGRAM, ENEWETAK ATOLL, REPUBLIC OF THE MARSHALL ISLANDS Part 1: Drilling operations and descriptions of bore holes in vicinity of KOA and OAK craters U.S. Geological Survey Open-File Report 86-419 1986 UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL SURVEY Pacific Enewetak Atoll Crater Exploration (PEACE) Program Enewetak Atoll, Republic of the Marshall Islands Part 1: Drilling operations and descriptions of boreholes in vicinity of KOA and OAK craters by 1 23 Thomas W. Henry , Bruce R. Wardlaw , Betty Skipp , Richard P. Major , and Joshua I. Tracey, Jr. U.S. Geological Survey Open File Report 86-419 Prepared in cooperation with the Defense Nuclear Agency This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards and stratigraphic nomenclature. 1O Q / Reston, VA; Washington, DC; Denver, CO; Denver, CO, currently Austin, TX 1986 Use of trade names is for identification only and does not constitute endorsement either by the U.S. Geological Survey or by the Defense Nuclear Agency. CONTENTS Page INTRODUCTION ...................................................... 1 General Objectives of PEACE Program ........................... 1 Overview of USGS Role in PEACE Program ........................ 1 USGS Reports .................................................. 4 Phase II Participants and Roles ............................... 6 Acknowledgments ............................................... 9 Location and Setting .......................................... 11 Brief History of Enewetak ..................................... 13 Pacific Proving Grounds and Enewetak Nuclear Testing .......... 14 History of Previous Geologic Investigations ................... 15 Studies from 1946-1952 ................................... 15 First Boreholes ..................................... 15 AEC-LASL Drilling (1950-51) . .........................18 USGS-AEC Drilling (1951-52) ......................... 18 Interim Period (1952-1970) ............................... 21 Studies from 1970-1981 ................................... 22 PACE Program (1970-72) .............................. 22 EXPOE Program (1973-74) ............................. 22 EASI Program (1979-81) .............................. 27 Interim Events (1981-1984) Leading to PEACE Program ...... 27 DRILLING PROGRAM .................................................. 29 Drill Ship and Support Equipment .............................. 29 Ship, Facilities, and Crew ............................... 29 Drill Equipment .......................................... 32 Determination of Location (Navigation) ........................ 32 Determination of Water Depth .................................. 39 Coring/Sampling Techniques .................................... 40 Sampling in Soft Materials ............................... 41 Rock Sampling ............................................ 41 Combination Sampling ..................................... 41 Procedures for Shipboard Core and Sample Handling ............. 43 Downhole Geophysical Logs ..................................... 51 Borehole Nomenclature ......................................... 54 Borehole Statistics ........................................... 56 KOA Crater ............................................... 56 OAK Crater ............................................... 56 PEACE-Program Drilling Strategy ............................... 61 General Comments ......................................... 61 KOA Drilling Rationale ................................... 67 KOA Site A .......................................... 68 KOA Ground-Zero Hole ................................ 70 KOA Transition Boreholes ............................ 71 Lessons Learned from Drilling KOA ................... 72 OAK Drilling Rationale ................................... 73 OAK Site A .......................................... 73 OAK Ground-Zero Hole ................................ 74 Northeastern-Radial Transition Boreholes ............ 75 CONTENTS (cont.) Southeastern-Transect Boreholes ..................... 76 Southwestern-Transect (Gravimetry) Boreholes ........ 78 Reference Hole OOR-17 .......................... 78 Bathymetric-Center Borehole .................... 79 Borehole OQT-19 ................................ 79 Borehole ORT-20 ................................ 80 Borehole OSR-21 ................................ 80 Borehole OSM-22 ................................ 81 Borehole OTG-23 ................................ 81 Borehole Northwest of Ground Zero (OUT-24) .......... 81 LITHIC NOMENCLATURE ............................................... 83 Format and Nomenclature ....................................... 83 Rock or Geologic Unit Name ............................... 84 Primary Descriptors ...................................... 88 Grain Constituents or Biotic Modifiers .............. 88 Cementation ......................................... 89 Alteration .......................................... 89 Rock Color .......................................... 90 Grain Characteristics ............................... 91 Porosity ............................................ 91 Structures .......................................... 94 Secondary Descriptors .................................... 94 Sample Types ............................................. 95 Stratigraphic and Other Contacts ......................... 95 BOREHOLE DESCRIPTIONS ............................................ 98 KOA Crater ................................................... 102 Borehole KAR-1 .......................................... 103 Borehole KBZ-4 .......................................... 143 Borehole KCT-5 .......................................... 174 Borehole KDT-6 .......................................... 185 Borehole KET-7 .......................................... 191 Borehole KFT-8 .......................................... 195 OAK Crater ................................................... 206 Borehole OAR-2A .......................................... 210 Borehole OAR-2 .......................................... 227 Borehole OBZ-4 .......................................... 246 Borehole OCT-5 .......................................... 301 Borehole ODT-6 .......................................... 321 Borehole OET-7 .......................................... 328 Borehole OFT-8 .......................................... 338 Borehole OGT-9 .......................................... 349 Borehole OHT-10 .......................................... 353 Borehole OIT-11 .......................................... 359 Borehole OJT-12 .......................................... 369 Borehole OKT-13 .......................................... 375 Borehole OLT-14 .......................................... 390 Borehole OMT-15 .......................................... 394 ii CONTESTS (cont.) Borehole ONT-16 .......................................... 400 Borehole OOR-17 .......................................... 408 Borehole OPZ-18 .......................................... 438 Borehole OQT-19 .......................................... 449 Borehole ORT-20 .......................................... 462 Borehole OSR-21 .......................................... 472 Borehole OSM-22 .......................................... 481 Borehole OTG-23 .......................................... 484 Borehole OUT-24 .......................................... 489 REFERENCES ....................................................... 498 APPENDIX I: USGS SAMPLE AND RECOVERY DATA TABLES ............... 1-1 (Table of contents preceeds data tables.) APPENDIX II: McCLELLAND GEOTECHNICAL INFORMATION ................ II-l (Table of contents preceeds text.) APPENDIX III: DEPARTMENT OF ENERGY RADIOLOGICAL MONITORING ..... III-l (Table of contents preceeds text.) iii ILLUSTRATIONS Figure Page 1. Location map of Marshall Islands ........................ 2 2. Map of Republic of the Marshall Islands ................. 3 3. Map of Enewetak Atoll with principal craters and ........ 12 island names 4. Map of Enewetak nuclear-detonation sites ................ 17 5. Location of 1950-52 boreholes ........................... 19 6. Correlation of deep boreholes drilled from 1947-1952 .... 20 7. Location of PACE-Program boreholes ...................... 23 8. Location of EXPOE-Program boreholes ..................... 24 9. Geologic cross section of Engebi (JANET) Island ......... 26 10. Views of drill ship M/V Knut Constructor ................ 31 11. Views of laboratories and sample-preparation area ....... 35 12. Views of logging shed ................................... 37 13. PEACE-Program drill rig ................................. 38 14. Flow chart of core/sample-handling procedures ........... 44 15. Views of MEI core handlers .............................. 47 16. Views of activity in sample-preparation area ............ 49 17. Slabbing core and packing core craters .................. 50 18. KOA-crater borehole sites and seismic lines ............. 57 19. OAK-crater borehole sites and seismic lines ............. 58 20A. KOA-crater sidescan sonar map with crater provinces ..... 62 20B. Sidescan-sonar map KOA crater with borehole locations ... 63 21A. OAK-crater sidescan-sonar map with crater provinces ..... 64 2IB. Sidescan-sonar map OAK crater with borehole locations ... 65 22. Map of KOA/MIKE area with nuclear-shot sites ............ 69 23. Dunham's classification of carbonate rocks .............. 85 24. PEACE Program carbonate-rock classification