Thermal effects of pyroxenites on mantle melting below mid-ocean ridges

被引:54
作者
Brunelli, Daniele [1 ,2 ]
Cipriani, Anna [1 ,3 ]
Bonatti, Enrico [2 ,3 ]
机构
[1] Univ Modena & Reggio Emilia, Dipartimento Sci Chim & Geol, Modena, Italy
[2] CNR, Ist Sci Marine, Bologna, Italy
[3] Columbia Univ, Lamont Doherty Earth Observ, New York, NY 10027 USA
基金
美国国家科学基金会;
关键词
SOUTHWEST INDIAN RIDGE; MID-ATLANTIC RIDGE; HETEROGENEOUS MANTLE; ABYSSAL PERIDOTITES; EXTRACTION; CONSEQUENCES; BENEATH; MORB; DISEQUILIBRIUM; CONSTRAINTS;
D O I
10.1038/s41561-018-0139-z
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
After travelling in Earth's interior for up to billions of years, recycled material once injected at subduction zones can reach a subridge melting region as pyroxenite dispersed in the host peridotitic mantle. Here we study genetically related crustal basalts and mantle peridotites sampled along an uplifted lithospheric section created at a segment of the Mid-Atlantic Ridge through a time interval of 26 million years. The arrival of low-solidus material into the melting region forces the elemental and isotopic imprint of the residual peridotites and of the basalts to diverge with time. We show that a pyroxenite-bearing source entering the subridge melting region induces undercooling of the host peridotitic mantle, due to subtraction of latent heat by melting of the low-T-solidus pyroxenite. Mantle undercooling, in turn, lowers the thermal boundary layer, leading to a deeper cessation of melting. A consequence is to decrease the total amount of extracted melt, and hence the magmatic crustal thickness. The degree of melting undergone by a homogeneous peridotitic mantle is higher than the degree of melting of the same peridotite but veined by pyroxenites. This effect, thermodynamically predicted for a marble-cake-type peridotite-pyroxenite mixed source, implies incomplete homogenization of recycled material in the convective mantle.
引用
收藏
页码:520 / +
页数:7
相关论文
共 56 条
[1]   Flexural uplift of a lithospheric slab near the Vema transform (Central Atlantic): Timing and mechanisms [J].
Bonatti, E ;
Brunelli, D ;
Buck, WR ;
Cipriani, A ;
Fabretti, P ;
Ferrante, V ;
Gasperini, L ;
Ligi, M .
EARTH AND PLANETARY SCIENCE LETTERS, 2005, 240 (3-4) :642-655
[2]   Mantle thermal pulses below the Mid-Atlantic Ridge and temporal variations in the formation of oceanic lithosphere [J].
Bonatti, E ;
Ligi, M ;
Brunelli, D ;
Cipriani, A ;
Fabretti, P ;
Ferrante, V ;
Gasperini, L ;
Ottolini, L .
NATURE, 2003, 423 (6939) :499-505
[3]   Pyroxenite Layers in the Northern Apennines' Upper Mantle (Italy)-Generation by Pyroxenite Melting and Melt Infiltration [J].
Borghini, Giulio ;
Rampone, Elisabetta ;
Zanetti, Alberto ;
Class, Cornelia ;
Cipriani, Anna ;
Hofmann, Albrecht W. ;
Goldstein, Steven L. .
JOURNAL OF PETROLOGY, 2016, 57 (04) :625-653
[4]   Meter-scale Nd isotopic heterogeneity in pyroxenite-bearing Ligurian peridotites encompasses global-scale upper mantle variability [J].
Borghini, Giulio ;
Rampone, Elisabetta ;
Zanetti, Alberto ;
Class, Cornelia ;
Cipriani, Anna ;
Hofmann, Albrecht W. ;
Goldstein, Steven L. .
GEOLOGY, 2013, 41 (10) :1055-1058
[5]   VARIATION WITH SPREADING RATE OF OCEANIC CRUSTAL THICKNESS AND GEOCHEMISTRY [J].
BOWN, JW ;
WHITE, RS .
EARTH AND PLANETARY SCIENCE LETTERS, 1994, 121 (3-4) :435-449
[6]   Discontinuous melt extraction and weak refertilization of mantle peridotites at the Vema lithospheric section (Mid-Atlantic ridge) [J].
Brunelli, D ;
Seyler, M ;
Cipriani, A ;
Ottolini, L ;
Bonatti, E .
JOURNAL OF PETROLOGY, 2006, 47 (04) :745-771
[7]   Percolation of enriched melts during incremental open-system melting in the spinel field: A REE approach to abyssal peridotites from the Southwest Indian Ridge [J].
Brunelli, Daniele ;
Paganelli, Emanuele ;
Seyler, Monique .
GEOCHIMICA ET COSMOCHIMICA ACTA, 2014, 127 :190-203
[8]   PLATE KINEMATICS OF THE SOUTH-ATLANTIC - CHRON C34 TO PRESENT [J].
CANDE, SC ;
LABRECQUE, JL ;
HAXBY, WF .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS, 1988, 93 (B11) :13479-13492
[9]   REVISED CALIBRATION OF THE GEOMAGNETIC POLARITY TIMESCALE FOR THE LATE CRETACEOUS AND CENOZOIC [J].
CANDE, SC ;
KENT, DV .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 1995, 100 (B4) :6093-6095
[10]   Formation of the axial relief at the very slow spreading Southwest Indian Ridge (49° to 69°E) [J].
Cannat, M ;
Rommevaux-Jestin, C ;
Sauter, D ;
Deplus, C ;
Mendel, V .
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 1999, 104 (B10) :22825-22843