Distinct slab interfaces found within mantle transition zone

November 09, 2020

Oceanic lithosphere descends into Earth's mantle as subducting slabs. Boundaries between the subducting slab and the surrounding mantle are defined as slab interfaces, whose seismic imaging is the key to understanding slab dynamics in the mantle. However, the existence of slab interfaces below 200 km remains elusive.

Prof. CHEN Qifu's group from the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS) and their collaborators observed two distinct seismic discontinuities within the mantle transition zone (~410 km to 660 km) beneath the western Pacific.

The two discontinuities represented the upper and lower boundaries of the subducted Pacific high-velocity slab, corresponding to the slab Moho and the surface of partially molten sub-slab asthenosphere, respectively.

This work was published in Nature Geoscience on Nov. 9.

The subduction process transports chemically differentiated and hydrated rocks into Earth's mantle, driving the cycles of heat and material changes between Earth's surface and its deep interior.

At shallow depths (<200 km), a variety of seismic reflection studies subduction zones have identified the upper and>The slab interfaces can be seismologically detected at shallow depths. However, how deep the seismic velocity discontinuities at slab interfaces can extend remains unclear, mainly due to the lack of high-resolution imaging of slab interfaces at depths below 200 km.

To understand the existence and origin of deep slab interfaces, the researchers took advantages of the dense seismic arrays in northeast China to study the upper mantle structures in the region.

They found sharp-dipping, double seismic velocity discontinuities within the mantle transition zone (~410 km to 660 km) beneath the western Pacific that coincide spatially with the upper and lower bounds of the high-velocity slab.

"Based on detail seismological analyses, the upper discontinuity was interpreted to be the Moho discontinuity of the subducted slab," said Prof. CHEN. "The lower discontinuity is likely caused by partial melting of sub-slab asthenosphere under hydrous conditions in the seaward portion of the slab."

The imaged distinct slab-mantle boundaries at depths between 410 and 660 km, deeper than previously observed, suggest a compositionally layered slab and high-water contents beneath the slab.
The study was done in collaboration with California Institute of Technology, Rice University, China University of Petroleum (Beijing), Earth Observatory of Singapore, Nanyang Technological University, Peking University, Institute of Earthquake Forecasting, China Earthquake Administration, and University of Illinois Urbana-Champaign.

The work was supported by the Strategic Priority Research Program (B) of Chinese Academy of Sciences and the National Natural Science Foundation of China.

Chinese Academy of Sciences Headquarters

Related Science Articles from Brightsurf:

75 science societies urge the education department to base Title IX sexual harassment regulations on evidence and science
The American Educational Research Association (AERA) and the American Association for the Advancement of Science (AAAS) today led 75 scientific societies in submitting comments on the US Department of Education's proposed changes to Title IX regulations.

Science/Science Careers' survey ranks top biotech, biopharma, and pharma employers
The Science and Science Careers' 2018 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.

Science in the palm of your hand: How citizen science transforms passive learners
Citizen science projects can engage even children who previously were not interested in science.

Applied science may yield more translational research publications than basic science
While translational research can happen at any stage of the research process, a recent investigation of behavioral and social science research awards granted by the NIH between 2008 and 2014 revealed that applied science yielded a higher volume of translational research publications than basic science, according to a study published May 9, 2018 in the open-access journal PLOS ONE by Xueying Han from the Science and Technology Policy Institute, USA, and colleagues.

Prominent academics, including Salk's Thomas Albright, call for more science in forensic science
Six scientists who recently served on the National Commission on Forensic Science are calling on the scientific community at large to advocate for increased research and financial support of forensic science as well as the introduction of empirical testing requirements to ensure the validity of outcomes.

World Science Forum 2017 Jordan issues Science for Peace Declaration
On behalf of the coordinating organizations responsible for delivering the World Science Forum Jordan, the concluding Science for Peace Declaration issued at the Dead Sea represents a global call for action to science and society to build a future that promises greater equality, security and opportunity for all, and in which science plays an increasingly prominent role as an enabler of fair and sustainable development.

PETA science group promotes animal-free science at society of toxicology conference
The PETA International Science Consortium Ltd. is presenting two posters on animal-free methods for testing inhalation toxicity at the 56th annual Society of Toxicology (SOT) meeting March 12 to 16, 2017, in Baltimore, Maryland.

Citizen Science in the Digital Age: Rhetoric, Science and Public Engagement
James Wynn's timely investigation highlights scientific studies grounded in publicly gathered data and probes the rhetoric these studies employ.

Science/Science Careers' survey ranks top biotech, pharma, and biopharma employers
The Science and Science Careers' 2016 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.

Three natural science professors win TJ Park Science Fellowship
Professor Jung-Min Kee (Department of Chemistry, UNIST), Professor Kyudong Choi (Department of Mathematical Sciences, UNIST), and Professor Kwanpyo Kim (Department of Physics, UNIST) are the recipients of the Cheong-Am (TJ Park) Science Fellowship of the year 2016.

Read More: Science News and Science Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.