Magmas trapped at the continental lithosphere-asthenosphere boundary

Research areas:

• Intérieurs planétaires (2011 - 2016)

Year:

2014

Authors:

• C. Crepisson
• G. Morard
• H. Bureau
• G. Prouteau
• Yann Morizet
• S. Petitgirard
• C. Sanloup

Journal:

EARTH AND PLANETARY SCIENCE LETTERS

Volume:

393

Pages:

105-112

Month:

MAY 1

ISSN:

0012-821X

BibTex:

@article{WOS:000335103800012, author = "C. Crepisson and G. Morard and H. Bureau and G. Prouteau and Yann Morizet and S. Petitgirard and C. Sanloup", abstract = "The lithosphere-asthenosphere boundary (LAB) beneath the continents is a key interface in plate tectonics, yet its nature remains elusive. A partial melt layer has been advocated to explain its geophysical characteristics. However, the main counter-argument is that such a layer cannot be stable as melts should rise through the lithosphere. Density measurements of volatile-containing alkali basalts taken as a proxy for LAB melts show that they are neutrally buoyant at the pressure (P)-temperature (T) conditions of the LAB under continents. Complementary X-ray diffraction and Raman data provide structural insights on melt compaction mechanisms. Basalts generated below the lithosphere may thus be gravitationally trapped and accumulate over time. Their presence provides answers to key questions on continental lithosphere geodynamics, and in particular on cratonic keels stability. This buoyancy trap would cease to exist at higher mantle T such as those relevant of the Archean, and as such, could be linked to the onset of plate tectonics. (C) 2014 Elsevier B.V. All rights reserved.", doi = "10.1016/j.eps1.2014.02.048", extra = "PICL", issn = "0012-821X", journal = "EARTH AND PLANETARY SCIENCE LETTERS", month = "MAY 1", pages = "105-112", title = "{M}agmas trapped at the continental lithosphere-asthenosphere boundary", volume = "393", year = "2014", }

Abstract:

The lithosphere-asthenosphere boundary (LAB) beneath the continents is a key interface in plate tectonics, yet its nature remains elusive. A partial melt layer has been advocated to explain its geophysical characteristics. However, the main counter-argument is that such a layer cannot be stable as melts should rise through the lithosphere. Density measurements of volatile-containing alkali basalts taken as a proxy for LAB melts show that they are neutrally buoyant at the pressure (P)-temperature (T) conditions of the LAB under continents. Complementary X-ray diffraction and Raman data provide structural insights on melt compaction mechanisms. Basalts generated below the lithosphere may thus be gravitationally trapped and accumulate over time. Their presence provides answers to key questions on continental lithosphere geodynamics, and in particular on cratonic keels stability. This buoyancy trap would cease to exist at higher mantle T such as those relevant of the Archean, and as such, could be linked to the onset of plate tectonics. (C) 2014 Elsevier B.V. All rights reserved.