CaltechAUTHORS
  A Caltech Library Service

Seismic evidence for the depression of the D″ discontinuity beneath the Caribbean: Implication for slab heating from the Earth's core

Ko, Justin Yen-Ting and Hung, Shu-Huei and Kuo, Ban-Yuan and Zhao, Li (2017) Seismic evidence for the depression of the D″ discontinuity beneath the Caribbean: Implication for slab heating from the Earth's core. Earth and Planetary Science Letters, 467 . pp. 128-137. ISSN 0012-821X. http://resolver.caltech.edu/CaltechAUTHORS:20170601-072541480

[img] MS Word - Supplemental Material
See Usage Policy.

2656Kb

Use this Persistent URL to link to this item: http://resolver.caltech.edu/CaltechAUTHORS:20170601-072541480

Abstract

The lowermost 100–300 km of the Earth's mantle commonly regarded as the thermal boundary layer (TBL) of mantle circulation is characterized by its complex physical properties. Beneath the Caribbean this so-called D″ layer features relatively high velocities and abrupt impedance increase at the top (designated as the D″ discontinuity). These seismic characteristics have been attributed to the accumulation of ancient subducted slab material and the phase transition in the major lower mantle mineral of pervoskite. Geodynamic models predict that the blanketing cold slabs may trap enough heat from core to be buoyantly destabilized, and eventually broken apart and entrained into the bottom of the convection cell. Here we explore the D″ structure with unprecedented resolution through modeling traveltimes, amplitudes, and waveform shapes from the USArray. We find an east-to-west asymmetrical undulation of the D″ discontinuity with a V-shaped depression of ∼70–160 km over a lateral distance of 600 km beneath northern South America. The shear velocity perturbations vary in the same trend showing the most pronounced reduction of ∼3–4% below the thinnest D″ layer in close proximity to an intermittently undetected discontinuity. The strong correlation between the D″ topography and velocity variations indicates the phase transition boundary has been perturbed or even disrupted by the large lateral temperature gradient of slab material which has been reheated from the core over extended periods of time.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.epsl.2017.03.032DOIArticle
http://www.sciencedirect.com/science/article/pii/S0012821X17301681PublisherArticle
ORCID:
AuthorORCID
Ko, Justin Yen-Ting0000-0003-1523-4494
Additional Information:© 2017 Elsevier B.V. Received 25 December 2016, Revised 24 March 2017, Accepted 26 March 2017, Available online 7 April 2017. We thank Eh Tan and Daoyuan Sun for fruitful discussions on the model interpretation. IRIS DMC provides earthquake waveform data used in our study. Editor Peter Shearer and two anonymous reviewers provide suggestions and comments that help greatly improve our manuscript. This work was supported by Ministry of Science and Technology of Taiwan grants, 101-2116-M-002-026 and 102-2116-M-002-025.
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Ministry of Science and Technology (Taipei)101-2116-M-002-026
Ministry of Science and Technology (Taipei)102-2116-M-002-025
Subject Keywords:shear wave triplication; waveform modeling; D″ discontinuity; post-perovskite phase transition; slab heating; thermal boundary layer
Record Number:CaltechAUTHORS:20170601-072541480
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20170601-072541480
Official Citation:Justin Yen-Ting Ko, Shu-Huei Hung, Ban-Yuan Kuo, Li Zhao, Seismic evidence for the depression of the D″ discontinuity beneath the Caribbean: Implication for slab heating from the Earth's core, Earth and Planetary Science Letters, Volume 467, 1 June 2017, Pages 128-137, ISSN 0012-821X, https://doi.org/10.1016/j.epsl.2017.03.032. (http://www.sciencedirect.com/science/article/pii/S0012821X17301681)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:77873
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:12 Jun 2017 16:22
Last Modified:02 Oct 2017 19:49

Repository Staff Only: item control page