TY - JOUR
T1 - Primordial metallic melt in the deep mantle
AU - Zhang, Zhou
AU - Dorfman, Susannah M.
AU - Labidi, Jabrane
AU - Zhang, Shuai
AU - Li, Mingming
AU - Manga, Michael
AU - Stixrude, Lars
AU - McDonough, William F.
AU - Williams, Quentin
N1 - Funding Information:
We thank Cin-ty Lee and another anonymous reviewer for their constructive comments. This manuscript originated from a project group discussion at the 2014 CIDER summer program at the Kavli Institute of Theoretical Physics at the University of California at Santa Barbara. We pay tribute to Adam Dziewonski, a member of the CIDER founding team. We acknowledge the leadership of Barbara Romanowicz and all participants in the program for feedback. We thank Dan Frost for discussion. CIDER was supported by the NSF Frontiers of Earth Systems Dynamics grant EAR-1135452. L.S. was supported by the European Research Council under advanced grant 291432 "Molten Earth" (FP7/2007-2013). S.D. thanks the Marie Heim-Vögtlin program of the Swiss National Science Foundation for support through project PMPDP2-151256. J.L. was supported by a Carnegie (Geophysical Laboratory) postdoctoral fellowship. M.M. was supported by the NSF under grant EAR-1135382. Q.W. was supported by the NSF under grant EAR-1215745. Z.Z. was supported by the NSF under grant EAR-1426772.
Publisher Copyright:
©2016. The Authors.
PY - 2016/4/28
Y1 - 2016/4/28
N2 - Seismic tomography models reveal two large low shear velocity provinces (LLSVPs) that identify large-scale variations in temperature and composition in the deep mantle. Other characteristics include elevated density, elevated bulk sound speed, and sharp boundaries. We show that properties of LLSVPs can be explained by the presence of small quantities (0.3-3%) of suspended, dense Fe-Ni-S liquid. Trapping of metallic liquid is demonstrated to be likely during the crystallization of a dense basal magma ocean, and retention of such melts is consistent with currently available experimental constraints. Calculated seismic velocities and densities of lower mantle material containing low-abundance metallic liquids match the observed LLSVP properties. Small quantities of metallic liquids trapped at depth provide a natural explanation for primitive noble gas signatures in plume-related magmas. Our model hence provides a mechanism for generating large-scale chemical heterogeneities in Earth's early history and makes clear predictions for future tests of our hypothesis.
AB - Seismic tomography models reveal two large low shear velocity provinces (LLSVPs) that identify large-scale variations in temperature and composition in the deep mantle. Other characteristics include elevated density, elevated bulk sound speed, and sharp boundaries. We show that properties of LLSVPs can be explained by the presence of small quantities (0.3-3%) of suspended, dense Fe-Ni-S liquid. Trapping of metallic liquid is demonstrated to be likely during the crystallization of a dense basal magma ocean, and retention of such melts is consistent with currently available experimental constraints. Calculated seismic velocities and densities of lower mantle material containing low-abundance metallic liquids match the observed LLSVP properties. Small quantities of metallic liquids trapped at depth provide a natural explanation for primitive noble gas signatures in plume-related magmas. Our model hence provides a mechanism for generating large-scale chemical heterogeneities in Earth's early history and makes clear predictions for future tests of our hypothesis.
KW - LLSVPs
KW - chemical heterogeneities
KW - deep mantle
KW - magma ocean
KW - metallic melt
KW - noble gas
UR - http://www.scopus.com/inward/record.url?scp=84968754916&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84968754916&partnerID=8YFLogxK
U2 - 10.1002/2016GL068560
DO - 10.1002/2016GL068560
M3 - Article
AN - SCOPUS:84968754916
SN - 0094-8276
VL - 43
SP - 3693
EP - 3699
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 8
ER -