TY - JOUR
T1 - Multiple seismic reflectors in Earth's lowermost mantle
AU - Shang, Xuefeng
AU - Shim, Sang-Heon
AU - De Hoop, Maarten
AU - Van Der Hilst, Robert
PY - 2014/2/18
Y1 - 2014/2/18
N2 - The modern view of Earth's lowermost mantle considers a D? region of enhanced (seismologically inferred) heterogeneity bounded by the core-mantle boundary and an interface some 150-300 km above it, with the latter often attributed to the postperovskite phase transition (in MgSiO3). Seismic exploration of Earth's deep interior suggests, however, that this view needs modification. Socalled ScS and SKKS waves, which probe the lowermost mantle from above and below, respectively, reveal multiple reflectors beneath Central America and East Asia, two areas known for subduction of oceanic plates deep into Earth's mantle. This observation is inconsistent with expectations from a thermal response of a single isochemical postperovskite transition, but some of the newly observed structures can be explained with postperovskite transitions in differentiated slab materials. Our results imply that the lowermost mantle is more complex than hitherto thought and that interfaces and compositional heterogeneity occur beyond the D? region sensu stricto.
AB - The modern view of Earth's lowermost mantle considers a D? region of enhanced (seismologically inferred) heterogeneity bounded by the core-mantle boundary and an interface some 150-300 km above it, with the latter often attributed to the postperovskite phase transition (in MgSiO3). Seismic exploration of Earth's deep interior suggests, however, that this view needs modification. Socalled ScS and SKKS waves, which probe the lowermost mantle from above and below, respectively, reveal multiple reflectors beneath Central America and East Asia, two areas known for subduction of oceanic plates deep into Earth's mantle. This observation is inconsistent with expectations from a thermal response of a single isochemical postperovskite transition, but some of the newly observed structures can be explained with postperovskite transitions in differentiated slab materials. Our results imply that the lowermost mantle is more complex than hitherto thought and that interfaces and compositional heterogeneity occur beyond the D? region sensu stricto.
KW - Mantle convection
KW - Mineral physics
KW - Seismic imaging
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U2 - 10.1073/pnas.1312647111
DO - 10.1073/pnas.1312647111
M3 - Article
C2 - 24550266
AN - SCOPUS:84894338797
SN - 0027-8424
VL - 111
SP - 2442
EP - 2446
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 7
ER -