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Titolo:
Extensional faulting and caldera collapse in the axial region of fast spreading ridges: Analog modeling
Autore:
Lagabrielle, Y; Garel, E; Dauteuil, O; Cormier, MH;
Indirizzi:
Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY 10964 USA Columbia Univ Palisades NY USA 10964 arth Observ, Palisades, NY 10964 USA Univ Rennes, Inst Geol, F-35042 Rennes, France Univ Rennes Rennes FranceF-35042 nes, Inst Geol, F-35042 Rennes, France Univ Bretagne Occidentale, UMR 6538 Domaines Ocean, IUEM, F-29280 Plouzane, France Univ Bretagne Occidentale Plouzane France F-29280 29280 Plouzane, France
Titolo Testata:
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
fascicolo: B2, volume: 106, anno: 2001,
pagine: 2005 - 2015
SICI:
0148-0227(20010210)106:B2<2005:EFACCI>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
EAST PACIFIC RISE; THIN-SKINNED EXTENSION; MID-OCEAN RIDGES; MAGMA CHAMBERS; LOWER CRUST; BENEATH; LITHOSPHERE; EVOLUTION; MELT; CONSTRAINTS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
62
Recensione:
Indirizzi per estratti:
Indirizzo: Lagabrielle, Y Ctr IRD, Lab Geol Geophys, BPA5,Promenade Larroque, Noumea 98848, New Caledonia Ctr IRD BPA5,Promenade Larroque Noumea New Caledonia 98848
Citazione:
Y. Lagabrielle et al., "Extensional faulting and caldera collapse in the axial region of fast spreading ridges: Analog modeling", J GEO R-SOL, 106(B2), 2001, pp. 2005-2015

Abstract

The axial high of the East Pacific Rise (EPR) is bounded by ridge-parallellateral grabens that develop 2-8 km off-axis. These troughs appear to lengthen away from the ridge crest, suggesting that tectonics is active at least 10 km away from the axis. Along 15-20% of the length of the ridge the axial high is notched by a summit trough 500 to 1800 m wide. These large axialtroughs represent elongated collapse calderas that form when the EPR magmareservoir (comprising the melt lens and the underlying crystal mush zone) deforms and compacts during periods of waning magma supply under continuousstretching. We report the results of analog experiments performed in orderto constrain the tectonic-magmatic evolution of the crestal region of fastspreading ridges and more particularly the possible link that may exist between the development of axial caldera and the creation of lateral along the crestal region. We used inflatable elongated balloons filled with water as an analog of the magma reservoir. The balloon is capped with a silicone layer representing hot rocks below the brittle-ductile transition and is covered by a sand layer representing the brittle crust. The sand surface was given a dome shape that approximates the morphology of a fast spreading ridge, Mobile walls activated by a stepping motor allowed us to conduct the deflation experiments during continuous extension. Combination of deflation and extension leads to the creation of two lateral depressions and one axial trough. The lateral depressions are controlled by normal faults, while the central trough is delineated by reverse faults. During balloon deflation, tectonic extension is accommodated away from the axis due to the presence ofthe ductile silicone layer, whereas the deflation of the axial reservoir is accommodated by the collapse of the overlaying brittle crust. This accounts (1) for the development of axial troughs as collapse calderas, and (2) for the ubiquitous formation of lateral grabens of the flanking tectonic province in response to the deformation of the crystal mush.

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Documento generato il 11/07/20 alle ore 20:00:40