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Title: Kinematics and dynamics of the East Pacific Rise linked to a stable, deep-mantle upwelling [Kinematics and dynamics of the East Pacific Rise linked to whole mantel convective motions]

Earth’s tectonic plates are generally considered to be driven largely by negative buoyancy associated with subduction of oceanic lithosphere. In this context, mid-ocean ridges (MORs) are passive plate boundaries whose divergence accommodates flow driven by subduction of oceanic slabs at trenches. We show that over the past 80 million years (My), the East Pacific Rise (EPR), Earth’s dominant MOR, has been characterized by limited ridge-perpendicular migration and persistent, asymmetric ridge accretion that are anomalous relative to other MORs. We reconstruct the subduction-related buoyancy fluxes of plates on either side of the EPR. The general expectation is that greater slab pull should correlate with faster plate motion and faster spreading at the EPR. Moreover, asymmetry in slab pull on either side of the EPR should correlate with either ridge migration or enhanced plate velocity in the direction of greater slab pull. Based on our analysis, none of the expected correlations are evident. This implies that other forces significantly contribute to EPR behavior. We explain these observations using mantle flow calculations based on globally integrated buoyancy distributions that require core-mantle boundary heat flux of up to 20 TW. The time-dependent mantle flow predictions yield a long-lived deep-seated upwelling that has its highestmore » radial velocity under the EPR and is inferred to control its observed kinematics. Lastly, the mantle-wide upwelling beneath the EPR drives horizontal components of asthenospheric flows beneath the plates that are similarly asymmetric but faster than the overlying surface plates, thereby contributing to plate motions through viscous tractions in the Pacific region.« less
Authors:
ORCiD logo [1] ; ORCiD logo [2] ;  [3] ; ORCiD logo [4] ; ORCiD logo [5] ;  [6] ;  [7]
  1. Univ. of Chicago, Chicago, IL (United States)
  2. Univ. du Quebec a Montreal, Quebec (Canada); Univ. of Florida, Gainesville, FL (United States)
  3. Univ. of Chicago, Chicago, IL (United States); Kent State Univ., Kent, OH (United States)
  4. Univ. du Quebec a Montreal, Quebec (Canada)
  5. Syracuse Univ., Syracuse, NY (United States)
  6. Univ. of Texas, Austin, TX (United States)
  7. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-551773
Journal ID: ISSN 2375-2548
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Science Advances
Additional Journal Information:
Journal Volume: 2; Journal Issue: 12; Journal ID: ISSN 2375-2548
Publisher:
AAAS
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; plate tectonics; plate Kinematics; plate dynamics; geodynamics; East Pacific Rise; tectonics; slab-pull; mantle dynamics; mid-oceanic ridges; ridge-residence times
OSTI Identifier:
1343008