2021-06-25

New progress has been made in the study of three-dimensional deformation of the subducting lithosphere in the Mariana Trench

By yqqlm yqqlm

China News Service, Guangzhou, June 25 (Wang Jian, Li Shu) The reporter learned from the Key Laboratory of Marginal Sea and Ocean Geology (OMG) of the South China Sea Institute of Oceanology, Chinese Academy of Sciences, that the laboratory’s deep-sea geodynamics subject group Assistant Researcher Zhang Jiangyang, Researcher Zhang Fan, Distinguished Researcher Lin Jian, and Professor Yang Hongfeng of the Chinese University of Hong Kong, have made important progress in the study of the three-dimensional flexural deformation of the subducting lithosphere in the Mariana Trench. The relevant results have been published online in Tectonophysics (“Tectonophysics”). “Learning”) magazine.

The Key Laboratory of Marginal Sea and Ocean Geology introduced that the Mariana Trench is located at the bottom of the Northwest Pacific Ocean. Its deepest “Challenger Abyss” is known as the fourth pole of the earth. Its deep trench is due to The western Pacific plate subducted under the Philippine plate. The plate flexes during the subduction process. When the stress exceeds the strength of the plate, the plate will fracture, forming a normal fault on the seafloor, and induce an earthquake. Sea water enters the earth’s interior through normal faults, and chemically reacts with surrounding mantle rocks, causing rock alteration (called serpentinization). The subducting slab eventually carried fluid to the depths of the earth and promoted volcanic activity. Therefore, studying the deformation of subducting plates is crucial to understanding the material and energy cycles in the shallow and deep parts of subduction zones, and the deepest Mariana Trench in the world is an ideal place to reveal the dynamics of subduction zones.

New progress has been made in the study of three-dimensional deformation of the subducting lithosphere in the Mariana Trench

<

p >Topographic map and model setting of Mariana Trench. Photographed by South China Sea Institute of Oceanology, Chinese Academy of Sciences

The researchers used the Mariana Trench as the object, and based on high-precision seabed topography, gravity anomalies, earthquakes and other data constraints, they simulated the three-dimensional plate deflection of the entire Mariana Trench for the first time , Calculated the flexural stress and the three-dimensional spatial variation of the rupture zone, and revealed that the water flux in the southernmost part of the Mariana subducting plate is significantly more than that in the north-central part. The rupture yield zone obtained by theoretical simulation is consistent with the observed surface normal faults, extensional earthquakes, and changes in the plate water-bearing area constrained by seismic wave speed.

The relevant person in charge of the Key Laboratory of Marginal Sea and Ocean Geology said that this study revealed the spatial distribution of the three-dimensional fracture zone of the Mariana subduction plate, and pointed out the three-dimensional deflection process of the lithosphere in the subduction zone. Importance, the model can be extended to the study of global subduction zones.

It is reported that this research was funded by the National Natural Science Foundation of China, Southern Ocean Science and Engineering Guangdong Laboratory (Guangzhou), Chinese Academy of Sciences China-Pakistan Earth Science Center, Hong Kong Research Grants Bureau and other projects. (End)