Melt Focusing Along Permeability Barriers at Subduction Zones and the Location of Volcanic Arcs

2020 ◽  
Vol 21 (12) ◽  
Author(s):  
Goeun Ha ◽  
Laurent G. J. Montési ◽  
Wenlu Zhu
Keyword(s):  
Subduction Zones ◽  
Volcanic Arcs

scholarly journals Melting of subducted sediments reconciles geophysical images of subduction zones

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
M. W. Förster ◽  
K. Selway
Keyword(s):  
Subduction Zones ◽  
Source Region ◽  
Volcanic Rocks ◽  
Electrically Conductive ◽  
Small Magnitude ◽  
Volcanic Arcs ◽  
Frictional Strength ◽  
Episodic Tremor And Slip ◽  
Episodic Tremor ◽  
Sediment Melting

AbstractSediments play a key role in subduction. They help control the chemistry of arc volcanoes and the location of seismic hazards. Here, we present a new model describing the fate of subducted sediments that explains magnetotelluric models of subduction zones, which commonly show an enigmatic conductive anomaly at the trenchward side of volcanic arcs. In many subduction zones, sediments will melt trenchward of the source region for arc melts. High-pressure experiments show that these sediment melts will react with the overlying mantle wedge to produce electrically conductive phlogopite pyroxenites. Modelling of the Cascadia and Kyushu subduction zones shows that the products of sediment melting closely reproduce the magnetotelluric observations. Melting of subducted sediments can also explain K-rich volcanic rocks that are produced when the phlogopite pyroxenites melt during slab roll-back events. This process may also help constrain models for subduction zone seismicity. Since melts and phlogopite both have low frictional strength, damaging thrust earthquakes are unlikely to occur in the vicinity of the melting sediments, while increased fluid pressures may promote the occurrence of small magnitude earthquakes and episodic tremor and slip.

Volcanic Islands

2005 ◽  
Author(s):  
Herman Th. Verstappen
Keyword(s):  
Southeast Asia ◽  
Subduction Zones ◽  
Plate Tectonics ◽  
Volcanic Rocks ◽  
Peninsular Malaysia ◽  
Volcanic Arcs ◽  
Marine Strata ◽  
General Terms ◽  
Tectonically Active ◽  
Volcanic Islands

Volcanism is of widespread occurrence in the tectonically active zones of Southeast Asia. It is a dominant feature in many (particularly smaller) islands where other landform types are absent or scarce. The geographic distribution, major landform types, exogenous and endogenous processes, resources, and hazards of southeast Asian volcanic environments are discussed, first in general terms, and thereafter by using the examples of two typical volcanic islands, Bali and Lombok (Indonesia), which also illustrate the interaction between tectonism and volcanism in this part of the world. The distribution pattern of volcanism in Southeast Asia is related to plate tectonics, as discussed in Chapter 1. Three major plates dominate the region: the Eurasian, Indo-Australian, and Pacific, each of which is composed of several sub-plates. They meet at a triple point situated south of the Bird’s Head of Papua. Volcanism develops where, at some distance from the deep sea trenches that mark subduction zones, the subducting material melts and the magma rises to the surface. Volcanic geanticlinal belts, known as volcanic arcs and stretching parallel to the subduction zones, are thus formed. The arcs are often affected by transcurrent or compartmental faulting, and their roofs may collapse in places. The activity of individual volcanoes comes to an end when the magma chambers concerned are emptied or become inactive otherwise. Volcanism becomes extinct in (part of ) a volcanic arc when subduction abates. It may shift in position with changes in the configurations of the related subduction zone and plates. The plates, subduction zones, and the location of the volcanoes in Southeast Asia are shown in Figure 1.1. All volcanoes discussed in this chapter are Quaternary volcanoes in the sense that the oldest and most eroded ones ended their activity in the Lower Quaternary. The volcanism is of the intermediate andesite–basaltic Circum-Pacific suite, but locally more acidic rocks (rhyolites, dacites, etc.) occur. Neogene volcanic materials, intercalated with marine strata, are common, particularly in the flanks of the volcanic arcs of the region. Volcanic rocks, dating from Cretaceous and older geological periods and related to Pre-Tertiary subduction patterns, occur in Peninsular Malaysia, Borneo, and other areas outside the present arcs.

scholarly journals Short-lived tectonic switch mechanism for long-term pulses of volcanic activity after mega-thrust earthquakes

2013 ◽  
Vol 5 (1) ◽  
pp. 811-839 ◽  
Author(s):  
M. Lupi ◽  
S. A. Miller
Keyword(s):  
Subduction Zone ◽  
Volcanic Activity ◽  
Subduction Zones ◽  
Short Circuit ◽  
Strike Slip ◽  
Magma Source ◽  
Strain Partitioning ◽  
Volcanic Arcs ◽  
Stress Changes

Abstract. Eruptive rates in volcanic arcs increase significantly after mega-thrust earthquakes in subduction zones. Over short to intermediate time periods the link between mega-thrust earthquakes and arc response can be attributed to dynamic triggering processes or static stress changes, but a fundamental mechanism that controls long-term pulses of volcanic activity after mega-thrust earthquakes has not been proposed yet. Using geomechanical, geological, and geophysical arguments, we propose that increased eruption rates over longer timescales are due to the relaxation of the compressional regime that accompanies mega-thrust subduction zone earthquakes. More specifically, the reduction of the horizontal stress σh promotes the occurrence of short-lived strike-slip kinematics rather than reverse faulting in the volcanic arc. The relaxation of the pre-earthquake compressional regime facilitates magma mobilization by providing a short-circuit pathway to shallow depths by significantly increasing the hydraulic properties of the system. The timescale for the onset of strike-slip faulting depends on the degree of shear stress accumulated in the arc during inter-seismic periods, which in turn is connected to the degree of strain-partitioning at convergent margins. We performed Coulomb stress transfer analysis to determine the order of magnitude of the stress perturbations in present-day volcanic arcs in response to five actual mega-thrust earthquakes; the 2005 M8.6, 2007 M8.5, and 2007 M7.9 Sumatra earthquakes; the 2010 M8.8 Maule, Chile earthquake; and the 2011 M9.0 Tohoku, Japan earthquake. We find that all, but one, the shallow earthquakes that occurred in the arcs of Sumatra, Chile and Japan show a marked lateral component. Our hypothesis suggests that the long-term response of volcanic arcs to subduction zone mega-thrust earthquakes will be manifested as predominantly strike-slip seismic events, and that these future earthquakes will be followed closely by seismic swarms, inflation, and other indications of a rising magma source.

Petrologic and geochemical role of serpentinite in subduction zones and plate interface domains

2015 ◽  
Vol 37 ◽  
pp. 61-64
Author(s):  
Marco Scambelluri ◽  
Enrico Cannaò ◽  
Mattia Gilio ◽  
Marguerite Godard
Keyword(s):  
Subduction Zones ◽  
Plate Interface

Evolution of Orogenic Plateaus at Subduction Zones - Sinking and raising the southern margin of the Central Anatolian Plateau

2018 ◽  
Author(s):  
David Fernández-Blanco
Keyword(s):  
Tectonic Evolution ◽  
Subduction Zones ◽  
Inversion Tectonics ◽  
High Discharge ◽  
Anatolian Plateau ◽  
Surface Uplift ◽  
Southern Margin ◽  
Wide Range ◽  
Forearc Basins ◽  
Orogenic Plateaus

Orogenic plateaus have raised abundant attention amongst geoscientists during the last decades, offering unique opportunities to better understand the relationships between tectonics and climate, and their expression on the Earth’s surface.Orogenic plateau margins are key areas for understanding the mechanisms behind plateau (de)formation. Plateau margins are transitional areas between domains with contrasting relief and characteristics; the roughly flat elevated plateau interior, often with internally drained endorheic basins, and the external steep areas, deeply incised by high-discharge rivers. This thesis uses a wide range of structural and tectonic approaches to investigate the evolution of the southern margin of the Central Anatolian Plateau (CAP), studying an area between the plateau interior and the Cyprus arc. Several findings are presented here that constrain the evolution, timing and possible causes behind the development of this area, and thus that of the CAP. After peneplanation of the regional orogeny, abroad regional subsidence took place in Miocene times in the absence of major extensional faults, which led to the formation of a large basin in the northeast Mediterranean. Late Tortonian and younger contractional structures developed in the interior of the plateau, in its margin and offshore, and forced the inversion tectonics that fragmented the early Miocene basin into the different present-day domains. The tectonic evolution of the southern margin of the CAP can be explained based on the initiation of subduction in south Cyprus and subsequent thermo-mechanical behavior of this subduction zone and the evolving rheology of the Anatolian plate. The Cyprus slab retreat and posterior pull drove subsidence first by relatively minor stretching of the crust and then by its flexure. The growth by accretion and thickening of the upper plate, and that of the associated forearc basins system, caused by accreting sediments, led to rheological changes at the base of the crust that allowed thermal weakening, viscous deformation, driving subsequent surface uplift and raising the modern Taurus Mountains. This mechanism could be responsible for the uplifted plateau-like areas seen in other accretionary margins. ISBN: 978-90-9028673-0

HOW MANY M9 EARTHQUAKES ARE POSSIBLE? INTERSEISMIC COUPLING AND RUPTURE PATCH MAGNITUDES ALONG 15 OF THE WORLD’S SUBDUCTION ZONES

2017 ◽  
Author(s):  
Shannon E. Graham ◽  
◽  
John P. Loveless ◽  
John P. Loveless ◽  
Brendan J. Meade ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Interseismic Coupling

Os isotopic composition of western Aleutian adakites: Implications for the Re/Os of oceanic crust processed through hot subduction zones

2021 ◽  
Vol 292 ◽  
pp. 452-467
Author(s):  
Rachel Bezard ◽  
Simon Turner ◽  
Bruce Schaefer ◽  
Gene Yogodzinski ◽  
Kaj Hoernle
Keyword(s):  
Isotopic Composition ◽  
Oceanic Crust ◽  
Subduction Zones
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