Related Experiment Video
Updated: Oct 2, 2025
08:14
Atom Probe Tomography Analysis of Exsolved Mineral Phases
Published on: October 25, 2019
7.4K
Boron isotopes in boninites document rapid changes in slab inputs during subduction initiation
Hong-Yan Li1,2,3, Xiang Li4,5, Jeffrey G Ryan6
1State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China. hongyanli@gig.ac.cn.
Nature Communications
|February 23, 2022
Summary
Subduction initiation involves rapid changes in melting sources, documented by boron isotopes in Izu-Bonin arc boninites. Early low-silica boninites formed from crustal melts, followed by high-silica boninites from altered slab sediments and basaltic melts.
Area of Science:
- Geochemistry
- Petrology
- Tectonics
Background:
- Subduction initiation mechanisms remain poorly understood.
- Early magmatism at convergent margins provides crucial insights into tectonic processes.
Purpose of the Study:
- To investigate the rapid changes in slab inputs during the onset of subduction.
- To understand the petrogenesis of early boninites in the Izu-Bonin arc.
Main Methods:
- Analysis of boron isotopes in boninites.
- Radiogenic isotope and elemental ratio analysis.
- Petrological modeling of melt sources.
Main Results:
- Boron isotope variations reveal rapid (~0.5-1 Myr) changes in slab inputs.
- Early low-silica boninites derived from heterogeneous hornblende-granulite facies melts.
- Later high-silica boninites produced by fluxing with fluids from sediments and basalts.
Conclusions:
- Initial subduction involved accretion of uppermost slab near the trench, possibly due to low-angle subduction.
- Rapid changes in boninite composition indicate a steepening subduction angle and cooling plate interface.
- This cooling facilitated subduction of sediments and basalts, generating hydrous fluids at lower temperatures.
Related Concept Videos
03:20Nuclear Transmutation
19.1K
Nuclear transmutation is the conversion of one nuclide into another. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle. The first manmade nucleus was produced in Ernest Rutherford’s laboratory in 1919 by a transmutation reaction, the bombardment of one type of nuclei with other nuclei or with neutrons. Rutherford bombarded nitrogen-14 atoms with high-speed α particles from a natural radioactive isotope of radium and observed...
19.1K
01:21Isothermal Processes
4.1K
A thermodynamic process that occurs at constant temperature is called an isothermal process. Heat slowly flows into the system or out of the system to maintain thermal equilibrium. Processes involving phase changes like water evaporation into steam or freezing water into ice at a constant temperature are examples of Isothermal Processes.
An ideal gas can also undergo isothermal expansion or compression.
For example, consider 1 mole of an ideal gas inside an isolated cylinder at initial volume V...
An ideal gas can also undergo isothermal expansion or compression.
For example, consider 1 mole of an ideal gas inside an isolated cylinder at initial volume V...
4.1K
01:52Atomic Mass
65.5K
Atoms — and the protons, neutrons, and electrons that compose them — are extremely small. For example, a carbon atom weighs less than 2 × 10−23 g. When describing the properties of tiny objects such as atoms, we use appropriately small units of measure, such as the atomic mass unit (amu). The amu was originally defined based on hydrogen, the lightest element, then later in terms of oxygen. Since 1961, it has been defined with regard to the most abundant isotope of...
65.5K
02:50Nuclear Fission
10.6K
Many heavier elements with smaller binding energies per nucleon can decompose into more stable elements that have intermediate mass numbers and larger binding energies per nucleon—that is, mass numbers and binding energies per nucleon that are closer to the “peak” of the binding energy graph near 56. Sometimes neutrons are also produced. This decomposition of a large nucleus into smaller pieces is called fission. The breaking is rather random with the formation of a large...
10.6K
03:18Nuclear Stability
20.4K
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together...
To hold positively charged protons together...
20.4K
01:11Atomic Nuclei: Larmor Precession Frequency
1.8K
The earth's gravitational field produces a 'twisting force' perpendicular to the angular momentum of a spinning mass (such as a spinning top) that causes the mass to 'wobble' around the gravitational field axis in a phenomenon called precession. Similarly, the magnetic moment (μ) of a spinning nucleus precesses due to an external magnetic field directed along the z-axis. The precession of the magnetic moment vector about the magnetic field is called Larmor precession,...
1.8K