Decompression of hot mantle rock upwelling beneath oceanic spreading centers causes it to exceed the melting point (solidus), producing magmas that ascend to form basaltic crust ~6 to 7 kilometers thick. The oceanic upper mantle contains ~50 to 200 micrograms per gram of water (HO) dissolved in nominally anhydrous minerals, which-relative to its low concentration-has a disproportionate effect on the solidus that has not been quantified experimentally. Here, we present results from an experimental determination of the peridotite solidus containing known amounts of dissolved hydrogen. Our data reveal that the HO-undersaturated peridotite solidus is hotter than previously thought. Reconciling geophysical observations of the melting regime beneath the East Pacific Rise with our experimental results requires that existing estimates for the oceanic upper mantle potential temperature be adjusted upward by about 60°C.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1126/science.aaj2165 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Massive carbon storage in convergent margins initiated by subduction of limestone.
Nat Commun
July 2021
State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences, Wuhan, China.
Remobilization of sedimentary carbonate in subduction zones modulates arc volcanism emissions and thus Earth's climate over geological timescales. Although limestones (or chalk) are thought to be the major carbon reservoir subducted to subarc depths, their fate is still unclear. Here we present high-pressure reaction experiments between impure limestone (7.
View Article and Find Full Text PDFPhlogopite-pargasite coexistence in an oxygen reduced spinel-peridotite ambient.
Sci Rep
June 2021
Dipartimento di Scienze della Terra, Università degli Studi di Torino, Via Valperga Caluso 35, 10100, Turin, Italy.
The occurrence of phlogopite and amphibole in mantle ultramafic rocks is widely accepted as the modal effect of metasomatism in the upper mantle. However, their simultaneous formation during metasomatic events and the related sub-solidus equilibrium with the peridotite has not been extensively studied. In this work, we discuss the geochemical conditions at which the pargasite-phlogopite assemblage becomes stable, through the investigation of two mantle xenoliths from Mount Leura (Victoria State, Australia) that bear phlogopite and the phlogopite + amphibole (pargasite) pair disseminated in a harzburgite matrix.
View Article and Find Full Text PDFDecompression of hot mantle rock upwelling beneath oceanic spreading centers causes it to exceed the melting point (solidus), producing magmas that ascend to form basaltic crust ~6 to 7 kilometers thick. The oceanic upper mantle contains ~50 to 200 micrograms per gram of water (HO) dissolved in nominally anhydrous minerals, which-relative to its low concentration-has a disproportionate effect on the solidus that has not been quantified experimentally. Here, we present results from an experimental determination of the peridotite solidus containing known amounts of dissolved hydrogen.
View Article and Find Full Text PDFPetit-spot as definitive evidence for partial melting in the asthenosphere caused by CO.
Nat Commun
February 2017
Center for Northeast Asian Studies, Tohoku University, Kawauchi 41, Aoba-ku, Sendai 980-8576, Japan.
The deep carbon cycle plays an important role on the chemical differentiation and physical properties of the Earth's mantle. Especially in the asthenosphere, seismic low-velocity and high electrical conductivity due to carbon dioxide (CO)-induced partial melting are expected but not directly observed. Here we discuss the experimental results relevant to the genesis of primitive CO-rich alkali magma forming petit-spot volcanoes at the deformation front of the outer rise of the northwestern Pacific plate.
View Article and Find Full Text PDFDetection of melting by X-ray imaging at high pressure.
Rev Sci Instrum
June 2014
Mineral Physics Institute, Stony Brook University, Stony Brook, New York 11794-2100, USA.
The occurrence of partial melting at elevated pressure and temperature is documented in real time through measurement of volume strain induced by a fixed temperature change. Here we present the methodology for measuring volume strains to one part in 10(-4) for mm(3) sized samples in situ as a function of time during a step in temperature. By calibrating the system for sample thermal expansion at temperatures lower than the solidus, the onset of melting can be detected when the melting volume increase is of comparable size to the thermal expansion induced volume change.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!