Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Subduction channel processes: New progress in plate tectonic theory

16.09.2013
The plate tectonic theory has been primarily developed in three stages. (1)

From continental drift and seafloor spreading to oceanic subduction, laying a physical foundation of the plate tectonic theory. This was achieved by the recognitions that continents would be assembled to build a supercontinent Pangea with subsequent breakup to yield the present configuration, lithospheric plates buoyantly move on the asthenospheric mantle, and oceanic crust is subducted along trenches into the mantle. (2)


Two processes occur at the slab-mantle interface in continental subduction channel, with (a) physical mixing to produce the tectonic mélange of metamorphic rocks, and (b) chemical reaction of the overlying subcontinental lithospheric mantle (SCLM) wedge with aqueous fluid and hydrous melt from subducting continental crust.

Credit: ©Science China Press

From oceanic subduction to continental subduction and collision orogeny, with the first round of revolution to the plate tectonic theory due to the recognition of continental deep subduction to mantle depths. While deeply subducted oceanic crust was processed in the mantle and the returned to the surface by mafic magmatism, deeply subducted continental crust underwent ultrahigh pressure metamorphism at mantle depths and then exhumed to the surface as coherent mélanges.

This provides a geodynamic framework of tectonic processes for continental accretion and assemblage through arc-continent and continent-continent collision orogenies. (3) From continental collision and marginal orogeny to intracontinental reworking, emphasizing the inheritance of orogenic materials in postcollisional stages. While continental collision results in continental accretion through marginal orogeny, intercontinental orogens are converted to intracontinental orogens. The deeply subducted continental crust is processed in subduction channel underlying the mantle wedge, with partial return to the surface.

These have thrown new lights on developing the plate tectonic theory to encompass the continental tectonics, and thus directed further study toward solution to such questions as how thinning of the orogenic lithosphere and upwelling of the asthenospheric mantle affect postcollisional reworking of the intracontinental materials.

Finding of ultrahigh pressure index minerals such as coesite and diamond in metamorphic rocks of continental supercrustal protolith demonstrate that these rock were subducted to mantle depths for ultrahigh pressure metamorphism and then returned back to the surface. The recognition of continental deep subduction by Earth scientists has not only developed the plate tectonic theory, but also expanded the chemical geodynamics focusing on the recycling of crustal material.

The study of ultrahigh pressure metamorphic rocks has made prominent progress in many aspects, achieving the recognitions that the processes of continental seduction and exhumation have caused not only various types of structural deformation and mineralogical reaction but also different extents of metamorphic dehydration and partial melting (Fig. 1). By means of studying various rocks in continental collision orogens, Earth scientists have set the geodynamic link between the subduction and exhumation of continental crust and the building of collision orogens.

Furthermore, it is established that bulk melting of the deeply subducted continental crust gives rise to granitic rocks whereas partial melting of the subducting supracrustal rocks produces felsic melt that reacts with the overlying mantle wedge peridotite to generate fertile and enriched mantle sources for mafic magmatism after their storage in different periods.

A research team at School of Earth and Space Sciences in University of Science and Technology of China has taken the rocks of continental collision orogens as the object, and performed a great deal of investigations from field observations and laboratory analyses. This leads to a tectonic analysis of geological processes in continental subduction factory, which is published in Chinese Science Bulletin 2013 (26) in the title "Continental subduction channel processes: Plate interface interaction during continental collision".

Leader of this team is Professor ZHENG Yongfei, Academician of the Chinese Academy of Sciences at Key Laboratory of Crust-Mantle Materials and Environments. Major participants are Prof. ZHAO Zifu and Dr. CHEN Yixiang. Earth scientists of China have made a series of prominent progresses in the forefront and hotspot field of subduction channel, and their studies have exemplified successful applications of new techniques, new methods and new ideas to development of the plate tectonic theory.

The recognition of continental deep subduction and ultrahigh pressure metamorphism has provided not only a turning point in developing the plate tectonic theory, but also an excellent opportunity to study the time and mechanism of reworking continental lithosphere. It is intriguing to ask the following questions:

(1) how are crustal slices detached at different depths and exhumed during continental subduction?

(2) how do physical mixing and chemical reaction proceed between the deeply subducted crust and the overlying mantle wedge?

(3) how are energy exchange and matter transfer realized at the plate interface of subduction zone?

Prof. Zheng said, to study subduction channel processes, to determine the physical mixing and chemical reaction between the deeply subducted crust and the overlying mantle wedge under ultrahigh pressure conditions, and to understand the interaction at the plate interface of continental subduction zone and its associated fluid action and element transport, are a key to unravel such mysteries of Earth.

Source article:

Zheng Y F, Zhao Z F, Chen Y X. Continental subduction channel processes: Plate interface interaction during continental collision. Chinese Science Bulletin, 2013, 58, doi: 10.1007/s11434-013-6066-x

Website: http://link.springer.com/article/10.1007/s11434-013-6066-x

Science China Press Co., Ltd. (SCP) is a scientific journal publishing company of the Chinese Academy of Sciences (CAS). For 50 years, SCP takes its mission to present to the world the best achievements by Chinese scientists on various fields of natural sciences researches.

Science China Press | EurekAlert!
Further information:
http://www.scichina.com/

More articles from Earth Sciences:

nachricht GPM sees deadly tornadic storms moving through US Southeast
01.12.2016 | NASA/Goddard Space Flight Center

nachricht Cyclic change within magma reservoirs significantly affects the explosivity of volcanic eruptions
30.11.2016 | Johannes Gutenberg-Universität Mainz

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>