How to interact between mantle and crustal components in the subduction zone?

May 24, 2019

The initiation of plate subduction on Earth may occur before 3 billion years ago or even Hadean. Subduction is the core process of plate tectonics, which gradually lead to the co-evolution of hydrosphere, atmosphere and biosphere with solid Earth, and realizes the material circulation and energy exchange between the spheres. According to the different tectonic attributes of the subduction zone, it can be divided into different mantle environments of oceanic-oceanic, oceanic-continental and continental-continental subduction zones. The mantle sections of supra-subduction zone (SSZ) ophiolites and mantle-wedge-type (MWT) orogenic peridotites represent the mantle fragments from oceanic and continental lithosphere in subduction zones, respectively. They are essential targets to study the crust-mantle interaction in subduction zones. The SSZ ophiolites can record melt/fluid-rock interaction, metamorphism, deformation, concentration of metallogenic elements and material exchange between crust and mantle, during the stages from the generation of oceanic lithosphere at spreading centers to the initiation, development, maturation and ending of oceanic subduction at continental margins. The MWT orogenic peridotites reveal the history of strong metamorphism and deformation during subduction, the multiple melt/fluid metasomatism, and the complex cycling of crust-mantle materials, during the subduction/collision and exhumation of continental plates.

The paper entitled "Subduction-zone peridotites and their records of crust-mantle interaction " was recently published in 2019(7) issue of Science China: Earth Sciences, written by Professor Zheng Jianping, China University of Geosciences (Wuhan). This study summarizes research progresses in terms of subduction-related peridotite massifs in the world, reveals the complex deformation and metamorphism process, the interaction of melt/fluid with crust-mantle rocks and the material circulation process in different stages of subduction zones from generation to maturity and even to extinction.

Along the slab/mantle interface in a subduction zone, strong and complex physical mixing, the exchange of crust-mantle materials and melt/fluid activities occur between the subducting slab and the mantle wedge. These processes can cause the large-scale tectonism, metamorphism, magmatism and mineralization along convergent plate boundaries. The mantle wedge is an important unit of a subduction-zone system. This wedge-shaped mantle is located between the subducting slab and the overlying crust, and connects the processes of material cycling and crust-mantle interaction in the Earth's interior. The crust-mantle physical interactions in the subduction channel are mainly manifested in the formation me?lange complexes by mechanical mixing of various rocks, the cracks and shear zones in mantle wedge peridotites, the plastic/brittle deformation in rocks and minerals, and the hydration of mantle wedge peridotites, which results in an important influence on the physical properties of rocks such as density, magnetism and velocity. The major way of element exchange and material cycling between crust and mantle in a subduction zone is through chemical interactions between melts/fluids and mantle wedge rocks. Within the silicatic rock-water system under different pressures and temperatures, the melts/fluids in subduction zones can be divided into the aqueous fluids, the hydrous melts and the supercritical fluids. These crust-mantle physical interactions mainly control the geometry and tectonic associations of orogen and mantle wedge, and also constrain the physical space for crust-mantle chemical interaction. Macro- and micro-scale deformation plays an important "catalyzed" role in metamorphism, melt/fluid activities and metasomatism within the crust-mantle interface of a subduction zone.
This research was funded by the National Natural Science Foundation of China (Grant Nos. 41520104003 & 41873032).

See the article:

Shi X F, Liu S F, Lin C F. 2019. Growth structures and growth strata of the Qianjiadian Basin in the western Yanshanfold and thrust belt, North China. Science China Earth Sciences, 62(7): 1092-1109

Science China Press

Related Subduction Zone Articles from Brightsurf:

The connectivity of multicomponent fluids in subduction zones
A team of researchers has discovered more about the grain-scale fluid connectivity beneath the earth's surface, shedding new light on fluid circulation and seismic velocity anomalies in subduction zones.

Distinct slab interfaces found within mantle transition zone
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.

New fault zone measurements could help us to understand subduction earthquake
University of Tsukuba researchers have conducted detailed structural analyses of a fault zone in central Japan to identify the specific conditions that lead to devastating earthquake.

A review of ridge subduction, magmatism and metallogenesis
Ridge subduction events are very common and important geodynamic processes in modern oceanic plate tectonics (Figure 1), and play an important role in the generation of arc magmatism, material recycling, growth and evolution of continental crust, deformation and modification of overlying plates and metallogenesis.

Is the Earth's transition zone deforming like the upper mantle?
In a recently published paper in Earth and Planetary Science Letters, researchers from the Geodynamics Research Center, Ehime University and the University of Lille combine numerical modeling of dislocation glide and results from diffusion experiments to revisit the rheology of wadsleyite, ringwoodite and majorite garnet under geological strain rates across the transition zone of the Earth's mantle based on theoretical plasticity modeling.

Scientists review the metallogenesis and challenges of porphyry copper systems above subduction zone
Porphyry copper ± molybdenum ± gold deposits (PCDs) are the most economically important magmatic-hydrothermal metallogenic system above subduction zones, which have supplied nearly 3/4 of the world's copper, 1/2 of the molybdenum and 1/5 of the gold, as well as large amounts of silver, zinc, tin and tungsten, with however their metallogenesis remaining controversial.

Does accelerated subduction precede great earthquakes?
A strange reversal of ground motion preceded two of the largest earthquakes in history.

Badger behavior inside the cull zone
A study led by researchers at international conservation charity ZSL (Zoological Society of London) and Imperial College London has found that culling drives badgers to roam 61% further afield -- helping to explain why the practice, intended to reduce bovine TB transmission, can sometimes exacerbate the problem instead

A Goldilocks zone for planet size
Harvard University researchers described a new, lower size limit for planets to maintain surface liquid water for long periods of time, extending the so-called Habitable or 'Goldilocks'' Zone for small, low-gravity planets.

Water detected on an exoplanet located in its star's habitable zone
An international study lead by UdeM astronomer Björn Benneke has detected water vapor on the planet K2-18b; this represents a major discovery in the search of alien life.

Read More: Subduction Zone News and Subduction Zone Current Events 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