The MoHole A Crustal Journey and Mantle Quest Workshop Report Kanazawa, Japan, 3-5 June 2010 Workshop Steering Committee : Benoît Ildefonse, Natsue Abe, Yoshio Isozaki (Chairs) Donna K. Blackman, J. Pablo Canales, Shuichi Kodaira, Greg Myers, Mladen R. Nedimovic, Damon A.H. Teagle, Susumu Umino (host), Douglas S. Wilson Report Writing Committee : B. Ildefonse (Chair), N. Abe, D.K. Blackman, J.P. Canales, Y. Isozaki, S. Kodaira, G. Myers, K. Nakamura, M. Nedimovic, N. Seama, A. Skinner, E. Takazawa, D.A.H. Teagle, M. Tominaga, S. Umino, D.S. Wilson, M. Yamao Contents Executive Summary............................................................................................................ 1 1. Introduction................................................................................................................... 4 2. Scientific Rationale for the MoHole, a Crustal Journey and Mantle Quest....................... 5 2.1. The Mohorovičić Discontinuity.............................................................................................................................5 2.2. Formation of the lower crust.................................................................................................................................6 2.3. Composition and hydration of the ocean crust..............................................................................................7 2.4. Limits and controlling factors of life...................................................................................................................8 2.5. Physical and chemical nature of the upper mantle ......................................................................................8 3. Geophysical Site Surveys.............................................................................................. 10 3.1. Scientific Requirements ........................................................................................................................................10 3.2. Technological Constraints....................................................................................................................................10 3.3. Potential Sites............................................................................................................................................................12 3.3.1. Cocos Plate (aka 1256 area)............................................................................................................................14 3.3.2. Off Southern/Baja California...........................................................................................................................15 3.3.3. Hawaii........................................................................................................................................................................16 3.4. Large Scale Surveys: Finding the Right Project Area................................................................................17 3.5. Small-Scale Surveys: Detailed Imaging of Project Area and Target...................................................18 4. Technology & Engineering Development...................................................................... 19 4.1. Mud Circulation Technology ...............................................................................................................................19 4.2. Logging/ Coring........................................................................................................................................................20 4.3. Drill Bit, Drill String, and Core Barrels............................................................................................................21 4.4. Drilling Mud................................................................................................................................................................21 4.5. Casing/Cementing ...................................................................................................................................................22 4.6. Assessing the Past Experience in Crustal Drilling......................................................................................23 4.7. Accumulating Experience in Hard-Rock Drilling .......................................................................................23 5. Operations ................................................................................................................... 24 5.1. Professional Planning.............................................................................................................................................24 5.2. Site Characterization Data....................................................................................................................................24 5.3. Well Design Considerations.................................................................................................................................25 5.3.1. Pilot Hole Options .................................................................................................................................................25 5.3.2. Well Control and Borehole Pressure Management................................................................................25 5.3.3. Mud program..........................................................................................................................................................25 5.3.4. Casing design ..........................................................................................................................................................25 5.3.5. Cementing plan ......................................................................................................................................................26 5.3.6. Directional drilling options...............................................................................................................................26 5.4. Downhole drilling tool selection .......................................................................................................................26 5.5. Downhole Measurements.....................................................................................................................................26 5.5.1. Drill collar measurements - Logging While Drilling/Measurement While Drilling ................26 5.5.2. Wireline tools..........................................................................................................................................................27 5.5.3. VSP experiment ......................................................................................................................................................27 5.5.4. Long-term monitoring........................................................................................................................................27 5.6. Logistics........................................................................................................................................................................27 6. Keys for success ........................................................................................................... 28 6.1. Geophysical surveys and Hole location..........................................................................................................28 6.2. Scientific coring, sampling and measurements...........................................................................................28 6.3. Broadening the scientific spectrum .................................................................................................................30 6.4. Drilling technology..................................................................................................................................................30 6.5. Industrial engagement...........................................................................................................................................31 6.6. Public engagement, outreach, education.......................................................................................................31 6.7. Anticipated time table for the MoHole project............................................................................................32 7. References ................................................................................................................... 33 8. Workshop Agenda........................................................................................................ 35 Thursday, June 3 - Day 1................................................................................................................................................35 Friday, June 4 - Day 2......................................................................................................................................................36 Saturday, June 5 - Day 3.................................................................................................................................................36 9. Workshop Participants................................................................................................. 37 Appendices ...................................................................................................................... 39 Appendix 1 - Scientific Objectives of Mission Moho proposal (2007).......................................................40 1. Primary Motivation for Mission Moho ................................................................................................................41