Chair: Jian Lin, USA, Jerome Dyment, France
Working Group Members:
Spain - Eulalia Gracia
USA - David Graham
Japan - Nobukazu Seama
USA - Garrett Ito
UK - Bramley Murton
Germany - Kaj Hoernle
India - Rajendra Kumar Drolia
Iceland - Freysteinn Sigmundsson
Portugal - Joaquim Freire Luis
France - Javier Escartín
The goal of this working group was to promote and facilitate global research to better understand the physical and chemical interactions between mantle plumes and mid-ocean ridges and their effects on seafloor geological, hydrothermal, and biological processes.
Hotspot-Ridge Interactions WG Update
Reprinted from InterRidge News 10.1 (Apr. 2001)
Nearly all of the global mid-ocean ridge system is hidden beneath the oceans, except where it interacts with hotspot mantle plumes, such as Iceland, the Azores, and the Galapagos. It is estimated that the hotspot mantle plumes affect > 12,000 km of the global mid-ocean ridge system. The hotspot plumes provide a unique tectonic window seeing into mantle convection and geochemical heterogeneities of the Earth's deeper layers. They also cause systematic geochemical, geological, and geophysical variations on the ridge system and provide shallow bathymetric regions for deep-sea biological colonies. The last decade has witnessed several exciting new discoveries on the internal structure of oceanic hotspots and their interaction with ridges. However, due to the complexity of hotspot-ridge interactions and the global distribution of hotspots, it is clear that improved communication is needed to make the future international investigations better coordinated, multi-disciplinary, and cost-effective.
The New Working Group
In 2000 the InterRidge Steering Committee recommended the creation of a new InterRidge Working Group on "Hotspot-Ridge Interactions". The first Working Group consists of ten scientists who are actively working on hotspot-ridge research from France, Germany, India, Japan, Portugal, Spain, UK, and US (a list of members can be found below). The charge of this new Working Group is to promote and facilitate global research to better understand the physical and chemical interactions between mantle plumes and mid-ocean ridges and their effects on seafloor geological, hydrothermal, and biological processes. A Working Group plan will be formulated in the upcoming months.
The first activity of the Working Group was the creation of an InterRidge web page on "Hotspot-Ridge Interactions" (http://www.intridge.org/hotspot.htm). The initial features of this web page include the geographic coordinates, relevant cruises, and research paper references on a global array of 18 near-ridge hotspots including Afar, Ascension, Azores, Balleny, Bouvet, Cobb, Discovery, Easter, Galapagos, Gough, Guadalupe, Iceland, Jan Mayen, Louisville, Marion, Shona, St. Paul/Amsterdam, and Tristan da Cunha. It is envisioned that this web page will eventually establish on-line access to the latest discoveries, references, abstracts, future conferences, new cruises, and shared data resources. The Working Group welcomes comments and suggestions on how this web page can be made most useful to researchers. Please send correspondence to the InterRidge office (firstname.lastname@example.org) or Working Group Chair Jian Lin (email@example.com).
The US RIDGE Program sponsored a workshop on "Physical and Chemical Effects of Mantle Plume - Spreading Ridge Interaction" on June 26-28, 2000 in Troutdale, Oregon (http://ridge.oce.orst.edu/meetings/PRIworkshop). The workshop was convened by Dave Graham, Garrett Ito, and John Chen and attended by approximately 50 researchers and students. The objectives of the workshop were (1) to provide a forum for discussing recent and ongoing research, (2) to assess our current understanding of mantle plume-spreading ridge systems, and (3) to identify the most important outstanding problems and establish a coordinated strategy to address them. Keynote talks and discussion sessions of the workshop were organized around three inter-linked themes of geodynamics and mantle flow, plate tectonic evolution, and magma genesis, crustal accretion and hydrothermal activity. A set of recommended investigative strategies will be included in a progressing workshop report. In addition, a special session on "Interaction between Hotspots and Mid-Ocean Ridges" was held during the European Geophysical Society (EGS) meeting on March 26-30, 2001 in Nice, France (Javier Escartin, Sara Bazin, and Wayne Crawford, convenors).
A symposium on 'Icelandic Plume and Crust' will be held in Iceland on September 8-10, 2001 (Emilie Hooft Toomey, Bryndís Brandsdóttir, and Sean Solomon, convenors). This meeting will bring together US, Icelandic, and international investigators to integrate new seismic results with modelling and geophysical, geological, and geochemical studies. The symposium is sponsored by the US National Science Foundation, the Iceland Research Council, the US RIDGE office, and the Svartsengi Geothermal Power Plant (http://ridge.oce.orst.edu/meetings/IceSeis2001).
The RIDGE "Integrated Studies" Sites
The "RIDGE 2000 Program" is being proposed to succeed the current RIDGE Program in the US. The new program is built around two multi-disciplinary, collaborative science themes, "Integrated Studies" and "Exploratory and Time-Dependent Studies" (http://ridge.oce.orst.edu). The "Integrated Studies" are envisioned to be "cohesive, integrated experiments at a small number of selected sites, designed to fully characterize the fundamental "type" units of the global system as integrated volcanic, tectonic and biological systems from mantle to ocean". In response to a call for nominations, the RIDGE office received two proposals from the US research community on hotspot-influenced spreading centre sites: the Galapagos and Iceland. The nominations for these and other "Integrated Studies" sites can be found in the RIDGE web page (http://ridge.oce.orst.edu/Integ_Studies).