<sup>40</sup>Ar/<sup>39</sup>Ar ages and zircon petrochronology for the rear arc of the Izu-Bonin-Marianas intra-oceanic subduction zone

Schmitt, Axel K.; Konrad, Kevin; Andrews, Graham; Horie, Kenji; Brown, Sarah; Koppers, Anthony A. P.; Pecha, Mark; Busby, Cathy J.; Tamura, Yoshihiko

doi:10.1080/00206814.2017.1363675

Cited by 22 publications

(20 citation statements)

References 99 publications

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“…The Izu‐Bonin arc, like other intraoceanic arcs, is typified by alkali‐poor and relatively low Zr melts and a scarcity of magmatic zircon. Zircon has been reported, however, in several tuffs recovered by Expedition 350 in the proximal Izu‐Bonin rear arc (Schmitt et al, ), in Late Miocene dacite from the Izu Peninsula, and in the 37.5 Ma Komahashi‐Daini tonalite (Tani et al, ). The provenance of U1438 detrital zircons in terms of the petrologic character of host melts provides insights into the genesis of Zr‐saturated magmas in the Izu‐Bonin arc.…”

Section: Discussionmentioning

confidence: 99%

Generation of Silicic Melts in the Early Izu‐Bonin Arc Recorded by Detrital Zircons in Proximal Arc Volcaniclastic Rocks From the Philippine Sea

Barth

Tani

Meffre

et al. 2017

Geochem Geophys Geosyst

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A 1.2 km thick Paleogene volcaniclastic section at International Ocean Discovery Program Site 351‐U1438 preserves the deep‐marine, proximal record of Izu‐Bonin oceanic arc initiation, and volcano evolution along the Kyushu‐Palau Ridge (KPR). Pb/U ages and trace element compositions of zircons recovered from volcaniclastic sandstones preserve a remarkable temporal record of juvenile island arc evolution. Pb/U ages ranging from 43 to 27 Ma are compatible with provenance in one or more active arc edifices of the northern KPR. The abundances of selected trace elements with high concentrations provide insight into the genesis of U1438 detrital zircon host melts, and represent useful indicators of both short and long‐term variations in melt compositions in arc settings. The Site U1438 zircons span the compositional range between zircons from mid‐ocean ridge gabbros and zircons from relatively enriched continental arcs, as predicted for melts in a primitive oceanic arc setting derived from a highly depleted mantle source. Melt zircon saturation temperatures and Ti‐in‐zircon thermometry suggest a provenance in relatively cool and silicic melts that evolved toward more Th and U‐rich compositions with time. Th, U, and light rare earth element enrichments beginning about 35 Ma are consistent with detrital zircons recording development of regional arc asymmetry and selective trace element‐enriched rear arc silicic melts as the juvenile Izu‐Bonin arc evolved.

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Section: Discussionmentioning

confidence: 99%

Generation of Silicic Melts in the Early Izu‐Bonin Arc Recorded by Detrital Zircons in Proximal Arc Volcaniclastic Rocks From the Philippine Sea

Barth

Tani

Meffre

et al. 2017

Geochem Geophys Geosyst

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“…The oldest known Neogene rear‐arc volcanism within the Izu‐Bonin is of two types. One is Unit VII at the bottom of Site U1437, consisting of ≤15.4 to 14 Ma depleted, tholeiitic, mostly mafic volcaniclastics (Sato et al, ; Schmitt et al, ; Wurth, ). The other is from several rear‐arc seamount chains (RASC) that trend approximately ENE‐WSW (Figure , mostly across the area labeled “rear arc” in Figure b; e.g., Taylor et al, ; see also Hochstaedter et al, ).…”

Section: Regional Context For Rhyolitic Volcanismmentioning

confidence: 99%

“…Many drilling cruises have focused on the Izu‐Bonin forearc and volcanic front (e.g., Fryer & Pearce, ; Reagan et al, ; Taylor et al, ), but Site U1437 represents the first drilling within the rear‐arc region (Figure ). In three consecutive cored holes, the JOIDES Resolution ultimately drilled down to 1,806.4 meters below seafloor (mbsf), through at least 15 Myr of volcaniclastic stratigraphy, with tephra and other volcano‐derived materials alternating with thick successions of tuffaceous mud (Figure ; Tamura et al, ; Gill et al, ; Schmitt et al, ). The core was subdivided into seven lithostratigraphic units, based on the relative proportion of mud to discrete ash or tephra.…”

Section: Sample Descriptionmentioning

confidence: 99%

Across‐Arc Diversity in Rhyolites From an Intra‐oceanic Arc: Evidence From IODP Site U1437, Izu‐Bonin Rear Arc, and Surrounding Area

Heywood

DeBari

Gill

et al. 2020

Geochem Geophys Geosyst

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Felsic magmas from the Izu‐Bonin rear arc have compositions that resemble average continental crust in some respects. In order to understand their origin, we studied 1.1–4.4 Ma tephras in a rear‐arc drill core from International Ocean Discovery Program Expedition 350, Site U1437. They provide a well‐dated record of changing magmatic compositions during the early stages of the most recent episode of Izu‐Bonin arc rifting. Based on our comprehensive recontextualization of published analyses of <7 Ma regional dredged rocks across the arc, basalts to rhyolites are shown to vary in coherent chronological and spatial trends and can be classified into three series: light rare earth element‐depleted volcanic front series; a rift‐related series with nearly flat rare earth element patterns; and light rare earth element‐enriched rear‐arc seamount chain‐type (RASC‐type) series, which are abundant in the studied Site U1437 tephra record. All three series erupted simultaneously between 4.4 and 1.1 Ma, including the RASC‐type rhyolites which erupted until 1.1 Ma in significant quantities. Remarkably, trace element and radiogenic isotope ratios are similar between rhyolites and basalts from the same region. This recontextualization of rhyolite affinity represents a significant departure from existing frameworks. Geochemical modeling shows that fractional crystallization can largely explain <4.4 Ma RASC‐type rhyolites with some additional open system processing evident in rhyolites with >73% SiO2. However, trace element and Hf isotope ratios preclude rear‐arc rhyolite derivation by partial melting of the Oligocene‐Eocene arc basement. Thus, we favor a model where fractional crystallization is more important than crustal melting in producing intra‐oceanic arc rhyolites in this region.

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“…Zircon crystals were mounted in indium and their U-Th isotopic compositions analyzed using the University of California Los Angeles (USA) and Heidelberg University (Germany) large magnet radius ion microprobes (CAMECA ims 1270 and 1280-HR, respectively). Analytical procedures are described in Schmitt et al (2006), with the modification of using multi-collector detection (Schmitt et al, 2017). Accuracy of the relative sensitivity calibration for U/Th and background corrections were monitored by replicate analysis of equilibrium zircon standard AS3 mounted next to the unknowns (1099.1 Ma; Paces and Miller Jr., 1993).…”

Section: U-th Analysismentioning

confidence: 99%

Episodes of dormancy and eruption of the Late Pleistocene Ciomadul volcanic complex (Eastern Carpathians, Romania) constrained by zircon geochronology

Molnár

Lukács

Dunkl

et al. 2019

Journal of Volcanology and Geothermal Research

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Ciomadul is the youngest volcanic system in the Carpathian-Pannonian Region recording eruptive activity from ca. 1 Ma to 30 ka. Based on combined zircon U-Th and (U-Th)/He geochronology, Ciomadul volcanism is divided into two main eruptive periods: Old Ciomadul (1 Ma-300 ka; OCEP) and Young Ciomadul Eruptive Period (160-30 ka; YCEP). OCEP activity comprises Eruptive Epochs 1-3, whereas new ages for eight lava domes and four pyroclastic units belonging to the YCEP lead to its further subdivision into two eruptive epochs: Eruptive Epochs 4 and 5. The extrusion of most of the lava domes occurred between 160 and 90 ka (Eruptive Epoch 4) during three eruptive episodes at ca. 155 ka, 135 ka and 95 ka (Eruptive Episodes 4/1, 4/ 2 and 4/3, respectively) along a NE-SW lineament, which is perpendicular to the regional NW-SE trend of the Călimani-Gurghiu-Harghita volcanic chain. Eruptive Epoch 5 occurred after a ca. 40 kyr of quiescence at ca. 55-30 ka, and is mainly characterized by explosive eruptions with a minor lava dome building activity. All of the dated pyroclastic outcrops, together with the lava dome of Piscul Pietros, belong to the older Eruptive Episode 5/1, with an eruption age of 55-45 ka. The eruption centers of Eruptive Epoch 5 are located at the junction of the conjugated NW-SE and NE-SW lineaments defined by the older eruptive centers. The whole-rock geochemistry of all studied samples is fairly homogeneous (SiO 2 = 63-69 wt%, K 2 O = 3-4 wt%). It also overlaps with the composition of the lava domes of the Old Ciomadul Eruptive Period, implying a monotonous geochemical characteristic for the past 1 Myr. The eruption rates for the Ciomadul volcanism were determined based on the erupted lava dome volume calculations, supplemented with the eruption ages. The activity peaked during the Eruptive Epoch 4 (160-90 ka), having an eruption rate of 0.1 km 3 /kyr. In comparison, these values are 0.05 km 3 /kyr for the YCEP (160-30 ka) and 0.01 km 3 /kyr for the overall Ciomadul volcanism (1 Ma-30 ka). Based on the geochemical characteristics, the quiescence periods and the lifetime of the complex, as well as the relatively small amount of erupted material, this volcanic system can be placed in a subduction-related post-collisional geodynamic setting, which shows strong chemical similarities to continental arc volcanism. The commonly found long repose times between the active phases suggest that the nature of a volcano cannot be understood solely based on the elapsed time since the last eruption. Instead, comprehensive geochronology, coupled with the understanding of the magma storage behavior could be a base of hazard assessment for volcanic fields, where the last eruptions occurred several 10's of thousand years ago and therefore they are not considered as potentially active.

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⁴⁰Ar/³⁹Ar ages and zircon petrochronology for the rear arc of the Izu-Bonin-Marianas intra-oceanic subduction zone

Cited by 22 publications

References 99 publications

Generation of Silicic Melts in the Early Izu‐Bonin Arc Recorded by Detrital Zircons in Proximal Arc Volcaniclastic Rocks From the Philippine Sea

Generation of Silicic Melts in the Early Izu‐Bonin Arc Recorded by Detrital Zircons in Proximal Arc Volcaniclastic Rocks From the Philippine Sea

Across‐Arc Diversity in Rhyolites From an Intra‐oceanic Arc: Evidence From IODP Site U1437, Izu‐Bonin Rear Arc, and Surrounding Area

Episodes of dormancy and eruption of the Late Pleistocene Ciomadul volcanic complex (Eastern Carpathians, Romania) constrained by zircon geochronology

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40Ar/39Ar ages and zircon petrochronology for the rear arc of the Izu-Bonin-Marianas intra-oceanic subduction zone

Cited by 22 publications

References 99 publications

Generation of Silicic Melts in the Early Izu‐Bonin Arc Recorded by Detrital Zircons in Proximal Arc Volcaniclastic Rocks From the Philippine Sea

Generation of Silicic Melts in the Early Izu‐Bonin Arc Recorded by Detrital Zircons in Proximal Arc Volcaniclastic Rocks From the Philippine Sea

Across‐Arc Diversity in Rhyolites From an Intra‐oceanic Arc: Evidence From IODP Site U1437, Izu‐Bonin Rear Arc, and Surrounding Area

Episodes of dormancy and eruption of the Late Pleistocene Ciomadul volcanic complex (Eastern Carpathians, Romania) constrained by zircon geochronology

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⁴⁰Ar/³⁹Ar ages and zircon petrochronology for the rear arc of the Izu-Bonin-Marianas intra-oceanic subduction zone