Investigating Continental Break-Up and Sedimentary Basin Formation
An IODP-MI International Workshop
The IODP Initial Science Plan highlights continental break-up and sedimentary basin formation as one of eight high-priority initiatives for scientific ocean drilling. Previous drilling efforts, concentrated largely in the North Atlantic Ocean, have identified two highly opposed end members of rifted margin formation. Within this context, this workshop will address the study of rifting and sedimentation processes in a global context, and will consider drilling strategies that include young, actively rifting margins using the full range of IODP drilling, logging, and borehole monitoring capabilities, including deep riser drilling.
Workshop participants are charged with:
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This workshop will take the first comprehensive look at the role of ocean drilling in the study of the processes by which continents rift to form new oceans since the work of the ODP North Atlantic Rifted Margins Detailed Planning Group (NARM DPG) in 1991. There have been spectacular advances in the understanding of continental rifting and the initiation of seafloor spreading since then, as well as advances in drilling, logging, monitoring, and site survey technologies that can be brought to bear on these problems. Unlike the NARM DPG, this workshop will adopt a global perspective.
As a result of: 1) ODP drilling off Greenland, Norway, Iberia, Newfoundland, the Woodlark basin, and near mid-ocean ridges worldwide, 2) complementary geophysical and geological studies around the globe, and 3) advances in both numerical and laboratory modeling of tectono-magmatic processes involving continental and oceanic lithosphere, we have radically changed the way we look at rifting and break-up. We now know that margins are fundamentally 3-dimensional, that they do not behave according to simple end-member models such as pure vs. simple shear, and that the nature of the rifting process changes spatially and temporally throughout a rifting period of finite length that precedes break-up. Planning for ocean drilling and complementary data acquisition must reflect this complexity. This workshop will synthesize the knowledge gained during the past 15 years to provide a base for planning future work.
There are many open questions regarding continental rifting and break-up. We do not yet understand the driving forces of rift initiation and continuation, nor the controls on the loci of rifting. We do not know the scale of deformation of the lower continental crust during rifting and nascent seafloor spreading. We do not understand the role of fluids and volatiles during rifting, nor the mechanisms by which huge volumes of magma are generated very quickly over wide areas at many rifted margins. We do not know the heat budget associated with rifting and the initiation of normal generation of oceanic lithosphere. Only a comprehensive, multi-disciplinary approach that includes ocean drilling will move us toward increased understanding. This workshop will serve to identify key questions and show how ocean drilling can help address them.
InterMARGINS, EUROMARGINS, US MARGINS, and other national margins-focused programs emerged after the work of NARM DPG. These programs are identifying high priority sites for the study of continental rifting and the initiation of seafloor spreading. For example, US MARGINS is concentrating on studying active rifts, and has selected the Gulf of California and the Red Sea as focus sites for its "Rupturing Continental Lithosphere" program. As another example, EUROMARGINS is focusing on the European passive margin system. It is likely that the large global passive margin efforts will lead to future IODP drilling proposals. Each potential study area, and the underlying strategy of studying active vs. inactive rifting, deserves discussion and consideration at the workshop.
Workshop participants are charged with synthesizing the base level of knowledge on continental break-up and sedimentary basin formation, defining key scientific objectives for studying these processes, identifying global, long-term drilling strategies, and specifying technological requirements for addressing these objectives. We will consider the full spectrum of rifted continental environments, including magma-dominated versus tectonic-dominated rifting, and older versus younger rifting. Participants will include scientists with expertise in magmatic, tectonic, and sedimentary processes, and whose methods range from field observation to geodynamic simulation. In addition, participating drilling engineers will provide information about enhanced drilling, logging, and long-term borehole monitoring capabilities of IODP.
Workshop participants will examine drilling strategies for investigating continental rifting and the formation of sedimentary basins. The potential of using the riser equipped D/V Chikyu to study rifted margins is not thoroughly understood and has not been widely discussed within this scientific community. Drilling operations using Chikyu provide the ability to use a riser and drilling mud to stabilize a hole when penetrating deep fractured and/or unstable formations. These are problems that have and will continue to plague deep drilling on rifted margins. However, the limitations that are most important are the current 2.5 km and projected 4 km lengths of riser that can be deployed. Some targets for future drilling on continental margins are in water deeper than 2.5-4 km and the D/V Chikyu riser cannot be used. The community needs to consider whether this limitation should guide us toward studying rifting and break-up processes in areas where useful drilling can be done in water depths less than 2.5-4 km, or whether we should continue working in areas where important problems can be addressed without the use of a riser. The workshop will provide a forum for educating the community about new drilling, logging, and borehole monitoring capabilities and foster discussion of the best ways and areas to deploy them for the advancement of our science.
Along with new technologies for drilling, sampling, downhole measurements, and borehole monitoring should come improved site characterization. Participants will discuss strategies for obtaining the very best seismic, other geophysical, and geological data to be used in locating, planning, and drilling IODP holes.
The workshop will comprise three days of meetings and a one-day field trip. If weather conditions are favorable, the field trip will take place on the first day. The field-trip to spectacular exposures of rifted continental crust and exhumed upper mantle in the Swiss Alps near St. Moritz will be led by Gianreto Manatschal from the UniversitÃ© Louis Pasteur Strasbourg
The meetings will be a mix of invited keynote addresses, short presentations by all participants who wish to speak, and breakout sessions. It is expected that the workshop will result in a short EOS meeting report and a longer, comprehensive workshop report that describes the scientific objectives, presents a drilling strategy for addressing those objectives, and identifies technological and engineering requirements.
The workshop agenda is currently being developed, and a full agenda will be posted here in the future. Please check back regularly for more information.
Mike Coffin (co-chair)
All members of the scientific and engineering community are invited to submit one or more one-page white papers to the steering committee. These papers will be used to develop the detailed program for the workshop and will be available to the community prior to the workshop. A white paper may address any topic of relevance to the workshop. We particularly seek white papers that suggest high priority objectives for future IODP drilling, locations where IODP should consider drilling to address important objectives, long-term drilling strategies, or key measurements that can be made in conjunction with IODP drilling.
The workshop will be held in Pontresina, Switzerland, September 15-18, 2006. Participants should plan to arrive on September 14 and depart on September 19. The workshop conveners will provide round-trip transportation from Zurich to Pontresina. The workshop will be held in Pontresina's RONDO Convention Center and will include a one-day field trip to the spectacular exposures of rifted continental crust and exhumed upper mantle in the Swiss Alps near St. Moritz.
More information will be provided as soon as it is available.
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