Detachment faults are now known to occur along a large portion of the earth's mid-ocean ridge system. This workshop, which is being run as an American Geophysical Union Chapman Conference in Cyprus in May of 2010, will bring together an international, interdisciplinary group of scientists to discuss these important, yet little understood, features. It will focus on identifing important gaps in our knowledge of detachment faults and their origin. Field excursions at the Troodos Ophiolite in Cyprus will allow participants to examine in detail, in an easily accessible location, key features of these structures. Empahsis will be on their tectonic significance, mechanisms of formation, and association with fluid seeps that host unusual deep sea organisms. Broader impacts of the work are strong in terms of training early career faculty, graduate students, and postdoctoral resaerchers in the recognition, characteristics, and impacts of these structures. Broad dissemination of workshop results will be facilitated by the production of a volume of papers that summarize the present state of knowledge and that identify important gaps in knowledge of these important and prolific tectonic settings.
Report for the General Public Oceanic core complexes are deep sections of the oceanic lithosphere exhumed to the seafloor by long-lived detachment faults formed along the flanks of mid-ocean ridges. In order to advance understanding of the fundamental processes that control oceanic detachment faulting and OCC formation and evolution, and associated geological, chemical, and biological phenomena, we organized a Chapman Conference on Detachments in Oceanic lithosphere: Deformation, Magmatism,Fluid Flow and Ecosystems in Agros, Cyprus, May 8-15, 2010. The conference was organized around 6 major science topics and consisted of 12 invited oral presentations, 78 poster presentations, 3 field trips, and discussions. The conference delivered three specific products: 1. A community statement: "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." 2. A consensus on terminology: 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. 3. A set of recommendations to advance research in this topic and strengthen the links between the scientific community and appropriate funding agencies: (a) To establish an InterRidge Working Group on Oceanic Detachment Faults that will serve for exchange of information, resources and personnel, to coordinate efforts with other research initiatives, and to facilitate future meetings workshops to evaluate progress in the field. (b) To promote the presence of science questions related to oceanic detachment faults in the new Ocean Drilling Program, and to coordinate drilling proposals targeting oceanic detachments and core complexes. (c)To explore the possibility of creating a new program within the NSF that would support multidisciplinary research on this topic. (d) To edit a Special Theme on Oceanic Detachments in the journal G-cubed that would gather contributions from participants to this meeting and the wider community, and to publish an article toEos summarizing of the results of this Conference and presenting to the broader audience the "Chapman Model" of lithospheric accretion associated with oceanic detachment faulting. The Summary was prepared by the conference conveners in January 2011.
