Oceanic Detachment Faults WG proposal

After the initial establishment of the Working Group (WG), membership to the WG will remain open to the international scientific community while the WG is active. New members interested in the WG theme will be expected to promote and contribute intellectually to the activities of the WG, and with ideas/suggestions that help carry on the mandate of the WG.

The scientific community held an AGU Chapman Conference on Oceanic Detachment Faults in Agros, Cyprus (8-15 May 2010), to advance understanding of the processes that control oceanic detachment faulting and associated geological, chemical, and biological phenomena. 86 scientists from fields in geosciences and biology attended the conference, which included overview talks on the topic, 3 days of field trips to the Troodos ophiolite, and poster sessions showcasing recent and on-going research and results. Documents, Conference presentations, and additional information from the conference are available at: www.ipgp.fr/rech/lgm/je/Chapman2010.

The conference deliverables include:
- A recommendation to establish an InterRidge (IR) WG to coordinate the wider scientific community and their efforts.  The study of oceanic detachment faults has seen an important surge in the last 10 years, mainly through individual projects, but it currently lacks overall community coordination. An IR WG could promote further advancement of research on the topic through integration of studies on specific topics and/or sites, the organization of Sessions at international meetings, establishing links to other programs and projects (i.e., IODP, GeoPRISMS), or convening a Conference in following years.

- A recommendation to edit a dedicated 'Theme' in the electronic journal G-cubed. In Summer 2010 G-cubed established a dedicated 'Theme on Oceanic Detachment faults', with J. Escartin, J.P. Canales, M. Cheadle, G. Fruh-Green, and B. John as Theme Editors. It currently consists of 15 publications (www.agu.org/journals/gc/themes.shtml).

- A community statement on oceanic detachments, and a consensus on the definition of oceanic detachment fault and oceanic core complex:

“The scientific community present at the 2010 Chapman Conference on Detachments in Oceanic Lithosphere affirmed that extension accommodated by oceanic detachment faults should be recognized as a fundamentally distinct mode of seafloor spreading that does not result in a classical Penrose model of oceanic crustal structure. This type of spreading is characterized by: formation of oceanic core complexes; tectonized and heterogeneous lithosphere; extensive exposure of gabbro and serpentinized mantle at the seafloor; some of the largest hydrogen-rich, deep-sea hydrothermal systems and mineral deposits; and large diversity in the deep-sea and subsurface biosphere. The recognition of this mode of spreading is one of the major advances in understanding plate tectonics in the last three decades.” 

An oceanic detachment fault is a large-offset normal fault formed at or in the vicinity of a mid-ocean ridge that accommodates a significant fraction of the plate separation.  Offsets range from kilometers to tens of kilometers or more. Oceanic detachment faults may initiate as steep normal faults at depth, and shallow into low angle extensional faults through rotation of the footwall.

An oceanic core complex results from the activity of an oceanic detachment fault. The oceanic core complex may expose the footwall of the oceanic detachment fault, exhuming lower crustal and mantle rocks, and be capped by a detachment fault surface that is often marked by corrugations and striations parallel to the extension direction. Alternatively, the detachment fault plane may be buried below the seafloor by rotated blocks of the hanging wall. 

This proposed IR WG shares interests with prior and on-going IR efforts, such as the Deep Earth Sampling WG, and the active WGs on Long-Range Exploration and Seafloor Mineralization. We believe that a dedicated WG on Oceanic Detachment Faults has the potential to help the community advance in an integrated understanding of the tectonic, magmatic, and hydrothermal processes that operate in association with this mode of oceanic accretion that is relatively unknown to date.

Working Group Roles and Planned Activities:
The specific aims of the proposed WG would include:

- Foster and strengthen links to other efforts and programs towards the study of oceanic detachment faults (e.g., GeoPRISMS, IODP, other IR WGs, etc.)

- Advance in the understanding of these structures through the planning of sessions at international meetings (EGU, AGU), and convening of a topic Workshop in the future.  

Specifically, we propose to facilitate interactions within the international community and foster scientific advancement, through the following actions:

a. Meet with members during 2012 AGU Fall meeting (or earlier if there are other meetings we all might attend) to agree on the roadmap ahead and future actions, follow-up on detachment-related cruises, and facilitate communication among groups and coordination of active/future projects.

b. Convene a session in 2013 AGU Fall Meeting (session proposal probably due in April 2013).

c. Organize a 2-3 day InterRidge Theoretical Institute on a specfic topic related to oceanic detachment faulting, (e.g., mechanics of detachment faults).  Tentative dates: Spring or Fall 2014.

d. Convene a session in the EGU meeting in Spring 2015.

e. Encourage the younger generation of scientists to organize/convene a topical Conference (AGU Chapman or similar) in oceanic detachment faulting to wrap up the theme (2016?).

- Through e-mailing/web site share information regarding on-going projects, planned cruises, and facilitate exchanges and cooperation among scientists.

- Playing a coordinating role for specific sites and projects if requested by the scientific community.

- Promote further contributions to the G-cubed Theme, which we expect will become a reference and key compilation of research results in the topic.

Proponents: J. P. Canales1 & J. Escartín2

1 Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA

2 Equipe de Géosciences Marines, CNRS/Institut de Physique du Globe de Paris, France

Proposed Management:

Co-Chairs: J. P. Canales, J. Escartín. 

Group Members:

Früh-Green, Gretchen; ETH, Switzerland, frueh-green@erdw.ethz.ch
Hayman, Nick; University of Texas, USA, hayman@utig.ig.utexas.edu
John, Barbara E; University of Wyoming, USA, bjohn@uwyo.edu
McCaig, Andrew; University of Leeds, UK, A.M.McCaig@leeds.ac.uk
Okino, Kyoko; Ocean Research Institute, Japan, okino@ori.u-tokyo.ac.jp
Reston, Timothy; University of Birmingham, UK, t.j.reston@bham.ac.uk
Smith, Deborah K; Woods Hole Oceanographic Institution, USA, dsmith@whoi.edu
Sun, Zhen; South China Sea Institute of Oceanology, China, zhensun@scsio.ac.cn