Journal
GEOLOGY
Volume 37, Issue 4, Pages 363-366Publisher
GEOLOGICAL SOC AMER, INC
DOI: 10.1130/G25428A.1
Keywords
-
Categories
Funding
- Incorporated Research Institutions for Seismology/Data Management System (IRIS/DMC)
- Northern California Earthquake Data Center
- Southern California Earthquake Data Center
- National Science Foundation [EAR-0609763]
Ask authors/readers for more resources
We employ a new thermodynamic method for self-consistent computation of compositional and thermal effects on phase transition depths, density, and seismic velocities. Using these profiles, we compare theoretical and observed differential traveltimes between P410s and P (T-410) and between P600s and P410s (T660-410) that are affected only by seismic structure in the upper mantle. The anticorrelation between T-410 and T660-410 suggests that variations in T-410 and T660-410 of similar to 8 s are due to lateral temperature variations in the upper mantle transition zone of similar to 400 K. If the mantle is a mechanical mixture of basaltic and harzburgitic components, our traveltime data suggest that the mantle has an average temperature of 1600 +/- 50 K, in agreement with temperature estimates from magma compositions of mid-ocean ridge basalts. We infer a 100 K hotter mantle if we assume the mantle to have a homogeneous pyrolitic composition. The transition-zone temperature beneath hotspots and within subduction zones is relatively high and low, respectively. However, the largest variability in T-410 and T660-410 is recorded by global stations far from subduction zones and hotspots. This indicates that the 400 K variation in upper mantle temperature is complicated by tilted upwellings, slab flattening and accumulation, ancient subduction, and processes unrelated to present-day subduction and plume ascent.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available