Composition of the slab-derived fluids released beneath the Mariana forearc: Evidence for shallow dehydration of the subducting plate

Ribeiro, Julia M.; Stern, Robert J.; Kelley, K. A.; Shaw, A. M.; Martínez, F.; Ohara, Yasuhiko

doi:10.1016/j.epsl.2015.02.018

Cited by 55 publications

(52 citation statements)

References 72 publications

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“…The IMI-30 was deployed in two main survey areas-along the Malaguana Gadao Ridge (MGR), the magmatically inflated southern Mariana backarc seafloor spreading center (Becker et al, 2010), and the SEMFR area ( Figure 2) at the eastern end of the rifted margin. Stern, P. Fryer, K. Kelley, and Y. Ohara. Results of the geochemical sampling in the SEMFR area and surrounding margin are reported in , , Ribeiro et al (2015Ribeiro et al ( , 2017, and Brounce et al (2014). Geophysical results from the MGR and its westward continuation as the diffuse spreading zone (DSZ) extending to the Southwest Mariana Rift (SWMR, Figure 2) are reported in a manuscript in preparation: "Diffuse spreading, a new mode of crustal accretion in the southern Mariana Trough backarc basin" by J. D. Sleeper, F. Martinez, R. J.…”

Section: Methods and Datamentioning

confidence: 99%

“…Geophysical results from the MGR and its westward continuation as the diffuse spreading zone (DSZ) extending to the Southwest Mariana Rift (SWMR, Figure 2) are reported in a manuscript in preparation: "Diffuse spreading, a new mode of crustal accretion in the southern Mariana Trough backarc basin" by J. D. Sleeper, F. Martinez, R. J. Stern, P. Fryer, K. Kelley, and Y. Ohara. Results of the geochemical sampling in the SEMFR area and surrounding margin are reported in , , Ribeiro et al (2015Ribeiro et al ( , 2017, and Brounce et al (2014). A geochemical study of the rifted arc volcanic front in this area, the Fina Nagu Volcanic Chain (FNVC; Figure 2), is given in Brounce et al (2016).…”

Section: Methods and Datamentioning

confidence: 99%

“…The main difference between these two systems appears to be the lack of fluid mobile trace elements, suggesting little hydrous flux from the slab in the first-formed forearc basalts (FABs) in the IBM system (Reagan et al, 2010;Reagan et al, 2017) contrasting with the significant enrichment in fluid mobile elements and measured elevated water contents in the SEMFR volcanics Ribeiro et al, 2015). This difference may be explained by the fact that the current southern Mariana rifted margin formed over a preexisting long-lived subduction zone.…”

Section: The Southern Mariana Margin As An Analog For Subduction Zonementioning

confidence: 99%

“…At mid-ocean ridges (MORs) mantle water content is low compared to convergent margins (Kelley et al, 2006). Thus, although melting and melt extraction remove water from the residual mantle (as shown by high water content in erupted lavas (Ribeiro et al, 2015)), slab dewatering provides a continual flux of new water, opposing mantle dehydration from melt extraction ( Figure 9b). Pressure gradients generated within the deforming and strengthening residual mantle matrix as it undergoes corner flow are thought to help focus melt delivery to the narrow ridge axis (Phipps Morgan, 1997).…”

Section: Implications For Narrow Plate Boundary Zones and Plate Tectomentioning

confidence: 99%

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Diffuse Extension of the Southern Mariana Margin

et al. 2018

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Extension within the southern Mariana margin occurs both normal to and parallel to the trench. Trench‐normal extension takes place along focused and broad backarc spreading axes forming crust that is passively accreted to the rigid Philippine Sea plate flank to the northwest. To the southeast, trench‐parallel extension has split apart the Eocene‐Miocene forearc terrain accreting new crust diffusely over a 150–200 km wide zone forming a pervasive volcano‐tectonic fabric oriented at high angles to the trench and the backarc spreading center. Earthquake seismicity indicates active extension over this forearc region and basement samples date young although waning volcanic activity. Such diffuse formation of new oceanic crust and lithosphere is unusual; in most oceanic settings extension rapidly focuses to narrow plate boundary zones—a defining feature of plate tectonics. Diffuse crustal accretion has been inferred to occur during subduction zone infancy, however. We hypothesize that in a near‐trench extensional setting, the continual addition of water from the subducting slab creates a weak overriding hydrous lithosphere that deforms broadly. This process counteracts mantle dehydration and strengthening proposed to occur at mid‐ocean ridges that may help to focus deformation and melt delivery to narrow plate boundary zones. The observations from the southern Mariana margin suggest that where lithosphere is weakened by high water content narrow seafloor spreading centers cannot form. These conditions likely prevail during subduction zone infancy, explaining the diffuse contemporaneous volcanism inferred in this setting.

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Section: Methods and Datamentioning

confidence: 99%

Section: Methods and Datamentioning

confidence: 99%

Section: The Southern Mariana Margin As An Analog For Subduction Zonementioning

confidence: 99%

Section: Implications For Narrow Plate Boundary Zones and Plate Tectomentioning

confidence: 99%

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Diffuse Extension of the Southern Mariana Margin

et al. 2018

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“…8a). Ba is strongly partitioned into aqueous fluids relative to Th, thus is a good proxy for the addition of subduction components released at shallow depths -sz1, Ba-only component of Pearce et al (2005) (Keppler, 2017;Ribeiro et al, 2015). Increasing Ba/Th ratio is mirrored by Sr/Nd ratio for Zambales, Oman and Troodos boninite (Fig.…”

Section: Shallow Slab Contributions To a Less Depleted Mantle Sourcementioning

confidence: 96%

Boninite and boninite-series volcanics in northern Zambales ophiolite: Doubly-vergent subduction initiation along Philippine Sea Plate margins

Perez¹,

Umino²,

Yumul³

et al. 2018

Preprint

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Abstract.A key component of subduction initiation rock suites is boninite, a high-magnesium andesite that is uniquely predominant in Western Pacific forearc terranes and in select Tethyan ophiolites such as Oman and Troodos. We report the discovery of low-calcium, high-silica boninite in the middle Eocene Zambales ophiolite (Luzon island, Philippines). Olivine-15 orthopyroxene microphyric high-silica boninite, olivine-clinopyroxene-phyric low-silica boninite and boninitic basalt occur Paleolatitudes derived from tilt-corrected sites in the Acoje Block place the juvenile arc of northern Zambales ophiolite in 25 the western margin of the Philippine Sea Plate. In this scenario, the origin of Philippine Sea Plate boninites (IBM and Zambales) would be in a doubly-vergent subduction initiation setting.

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Magnetotelluric imaging of a fossil paleozoic intraoceanic subduction zone in western Junggar, NW China

Yang

Sheng

et al. 2016

JGR Solid Earth

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The fate of subducted oceanic slabs can provide important clues to plate reconstruction through Earth history. Since oceanic slabs in continental collision zones are typically not well preserved, ancient subduction zones have rarely been imaged by geophysical techniques. Here we present an exception from the Darbut belt in the Junggar accretionary collage in the southern Altaids of Asia. We deployed a 182 km long magnetotelluric (MT) profile including 60 broadband sounding sites across the belt. Quality off‐diagonal impedances were inverted by a three‐dimensional scheme to image resistivities beneath the profile. The resistivity model along with MT impedance phase ellipses and induction vectors were tested and interpreted in detail. Combining geological and geophysical observations, mineral physical experiment, and geodynamic modeling results, the MT transect suggests a fossil intraoceanic subduction zone during the Late Paleozoic in the western Junggar that has been well preserved due to lack of significant subsequent tecto‐thermal events.

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Composition of the slab-derived fluids released beneath the Mariana forearc: Evidence for shallow dehydration of the subducting plate

Cited by 55 publications

References 72 publications

Diffuse Extension of the Southern Mariana Margin

Diffuse Extension of the Southern Mariana Margin

Boninite and boninite-series volcanics in northern Zambales ophiolite: Doubly-vergent subduction initiation along Philippine Sea Plate margins

Magnetotelluric imaging of a fossil paleozoic intraoceanic subduction zone in western Junggar, NW China

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