White Paper Title: 
Mantle and magma dynamics along the mid-ocean ridge system: combining ISS-scale with regional-scale perspectives

D.G. Pyle
SOEST, Department of Geology & Geophysics, University of Hawaii, Honolulu, HI 96822  (
D.W. Graham
College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331
B.B. Hanan
Department of Geological Sciences, San Diego State University, San Diego, CA 92181

Seafloor accretion at mid-ocean ridges is driven by transport of energy (heat) and mass (magma) from the mantle to the crust. Global variability in axial morphology and ridge segmentation reflect the variability in mantle temperature, spreading rate, magma supply, crustal faulting and large-scale plate motion. The R2K Integrated Study Site synthesis of mantle-to-microbe datasets is providing the RIDGE community with a thorough knowledge base for global comparison and investigation of the mid-ocean ridge system. Nonetheless, studies of mantle dynamics and ridge segmentation need to be considered in the context of large-scale (10’s to >100’s of kms) observations. Thus, there are some inherent limitations to addressing aspects of mantle heterogeneity and flow, ridge segmentation, and regional variability in mantle temperature and melt transport solely from the perspective of individual ISS focus areas. The “Mantle Controls Working Group” should, therefore, also consider existing (and possible future) regional data sets in the integration and synthesis of ISS data. While such regional studies would obviously include current ISS areas, other “analog” localities may provide key information that is currently lacking in the integration and synthesis effort. For example, event response cruises to the Northern Lau Basin broadened the scope of the ISS study for the Eastern Lau Spreading Center. As well, the Juan de Fuca and Gorda Ridges bear on the integration and synthesis of data from the Endeavor ISS. Moreover, many sections of the global MOR system display wide variations in axial morphology and geochemical characteristics over short distances (e.g., Equatorial Atlantic, Southeast Indian Ridge, Pacific-Antarctic Ridge). Regional scale geochemical variations provide important perspectives on mantle flow, mantle temperature and magma supply particularly when key variables, such as spreading rate, are relatively constant (e.g., SEIR; Amsterdam-St. Paul Plateau to the AAD & AAD to the Maquarie Triple Junction).

Most, if not all, R2K sub-disciplines have compelling rationales for expanding the footprint of current ISS areas, as well as for further survey of the mid-ocean ridge system at ocean basin and global scales. The recently released InterRIDGE workshop report, “Long Range Exploration of the Ridge Crests”, considers the future of global mid-ocean ridge research ( beyond the current ISS focus areas, and provides a initial blueprint for addressing the full spectrum of global mid-ocean ridge characteristics and processes.