Papers by Jun-Ichi Kimura
Japan Geoscience Union, Apr 7, 2014
American Mineralogist, Sep 1, 2021
The relationship between plutonic and volcanic components of magmatic plumbing systems continues ... more The relationship between plutonic and volcanic components of magmatic plumbing systems continues to be a question of intense debate. The Oki-Dōzen Islands, Sea of Japan, preserve outcrops of temporally associated plutonic, hypabyssal and volcanic rocks. Post-intrusion uplift juxtaposed Miocene syenites in inferred faulted contact with volcanic trachytes that are cut by rhyolite hypabyssal dikes. This provides a window deep into timing and origins of magma storage architecture and dynamics. Zircon is ubiquitous in all samples; our aim is to determine what its age and composition can reveal about the plutonic-volcanic connection. Here we show magma source characteristics are recorded in zircon Hf isotopes; source composition and assimilation of heterogeneous hydrothermally altered crust in zircon O isotopes; and extensive fractional crystallization in zircon trace elements. Combined with new U-Th-Pb SHRIMP zircon ages, 6.4-5.7 Ma, compositional data show pluton formation was by protracted amalgamation of discrete magma pulses. The rhyolite dike preserves an evolved fraction segregated from these discrete magmas. Synchronous with plutonism was volcanic eruption of trachyte magma derived from the same source, which may have stalled at a relatively shallow depth prior to eruption. Stalling occurred at least above the amphibole stability zone because amphibole-compatible Sc and Ti were not depleted in the trachyte melt resulting in elevated values of these in volcanic compared to plutonic zircon. Identifying smaller episodic magma pulses in a larger magmatic complex places constraints on potential magma fluxes and eruptible volumes. High-flux, large volume, plume-related ocean island magmatic systems may have extensive vertically distributed multi-stage magmatic reservoirs and subduction-related systems transcrustal magma reservoirs. By contrast, Oki-Dōzen was a low-flux system with incremental pluton growth and small-to moderate-scale eruptions.
Annual Meeting of the Geological Society of Japan The 122nd Annual Meeting(2015' Nagano), 2015
Minerals
In this study, the Sr isotope ratios (IRs; 87Sr/86Sr) of ferromanganese (Fe–Mn) crusts are analyz... more In this study, the Sr isotope ratios (IRs; 87Sr/86Sr) of ferromanganese (Fe–Mn) crusts are analyzed through laser ablation inductively coupled plasma multiple-collector mass spectrometry. A sample collected from off Minamitorishima Island showed uniform Sr IRs (0.70906–0.70927) similar to that of present-day seawater with more than 36 mm thickness. Meanwhile, a detritus-rich sample collected from off northeast (NE) Japan showed a wide variation in Sr IRs (0.707761–0.709963). The Sr IR variation in the Fe–Mn crust from off NE Japan suggests detrital influx contributions from both the NE Japan arc (<0.708) and aeolian dust from China (>0.718). Detrital flux from the NE Japan arc increases from the bottom to middle layers, possibly due to the uplift of the Ou backbone range that occurred after ~2 Ma. The increased influx of the aeolian dust in the outer layer is attributable to global cooling in the Quaternary that increased the loess dust transportation from China to the western...
Journal of Mineralogical and Petrological Sciences
We report in situ major and trace element and Li isotope analyses of murakamiite and Li-rich pect... more We report in situ major and trace element and Li isotope analyses of murakamiite and Li-rich pectolite in an albitite and whole-rock analyses of the albitite and host granite from Iwagi Islet, SW Japan. The albitite forms small bodies that are several tens of centimeters to tens of meters in size, disseminated in a host granite of Late Cretaceous age. The studied murakamiite-bearing albitite contains albite, sugilite, aegirine-augite, quartz, murakamiite-Li-rich pectolite, microcline, katayamalite, and accessory minerals. It shows conspicuous strain-induced textures. The murakamiite and Li-rich pectolite form a solid solution with Li × 100/(Li + Na) atomic ratios ranging from 44.2 to 60.1, and the Na line profiles show a zoning structure in which Na decreases from core to rim. Major and trace element compositions of murakamiite-pectolite normalized to that of albitite indicate the enrichments of some elements, particularly in Mn, Ca, Li, Sr, and REEs, roughly on the same order of magnitude (~10 times). The albitite-normalized element concentrations vary systematically with ionic radius of the element; the normalized concentrations of cations with the same valence roughly form a simple convex parabolic curve when plot against the ionic radius. This indicates that the element partitioning of murakamiite and pectolite during metasomatism to form albitite took place under a strong control of crystal structure, quasiequilibrated with metasomatic fluids and coexisting minerals. The δ 7 Li values of murakamiite and Li-rich pectolite show a wide range from −9.1 to +0.4‰ (average −2.9‰), and no obvious correlation with Li contents was observed. These δ 7 Li values should have resulted from hydrothermal fluid-rock interactions at the temperatures of 300-600°C. The very low δ 7 Li values down to −9.1‰ may have originated from intra-crystalline Li isotope diffusion, or involvement of deep-seated, Li-Na-enriched subduction-zone fluids with low δ 7 Li values.
The latest results of Earth's evolution and geological processes through 4.6 billion years from H... more The latest results of Earth's evolution and geological processes through 4.6 billion years from Hadean to Modern, based on various approaches including fieldworks, chemical analyses, experiments and computer simulation, will be presented. In this session, we aim to discuss and understand causal relationships and interplay among the evolution of Earth's deep interior, changes in the surface environments, and development and evolution of life. Wide-ranging topics are accepted.
Japan Geoscience Union, 2017
Ocean island basalts (OIBs) provide essential information on evolution of the Earth’s mantle, bec... more Ocean island basalts (OIBs) provide essential information on evolution of the Earth’s mantle, because OIBs are sourced from plumes from the deep mantle that include recycling materials. OIBs at the Pitcairn Island show distinct geochemical characteristics from other OIBs with their enriched isotopic signatures, so called enriched mantle 1 (EM1) component. This particular feature could have been caused by the involvement of recycled materials including chemically differentiated oceanic plate slab or delaminated continental lithosphere and lower crust (e.g., Eisele et al., 2002). In order to understand behavior of volatile elements during mantle recycling, we analyzed H2O, CO2, F, S, and Cl in the olivine-hosted melt inclusions in the Pitcairn OIBs using a secondary ion mass spectrometry (SIMS). Major and trace elements, and Pb isotope compositions were also determined on the same melt inclusions with an electron probe micro analyzer (EPMA) and a laser ablation-inductively coupled pla...
Japan Geoscience Union, 2017
Water-cerium ratio of basalt has been utilized for evaluating the water abundance in its source m... more Water-cerium ratio of basalt has been utilized for evaluating the water abundance in its source mantle due to its inheritance from the source mantle. However, dissimilar chemical properties of cerium (Ce; lithophile) to water (OH; volatile) in the mantle limit its quantification. Fluorine is an effective element for this purpose, because it is volatile element and has similar chemical properties to the mantle water. We precisely determined water and fluorine concentrations of deep submarine basaltic glasses from mid-oceanic ridges (MOR) of Pacific, Atlantic and Indian Ocean, a Hawaii hotspot, and a Fiji back arc basin using an FTIR and an ion chromatography. We found a strong linear correlation of F [ppm] = (477 ± 7) ×H2O [wt.%] + (47 ±2). This F–H2O mantle array represents melting of mantles ranging from a near-dry depleted MOR mantle (DMM: H2O = 100ppm; H2O/F=10) to a hydrous primitive mantle (PM: H2O = 750ppm; H2O/F=18.5). Other data of ours, produced by nanoSIMS, and existing da...
Japan Geoscience Union, 2014
Water-rock interactions reduce the rock strength, and possibly produce weak plate boundaries, ind... more Water-rock interactions reduce the rock strength, and possibly produce weak plate boundaries, inducing active plate tectonics. Water-rock interactions may also have geochemical impacts, causing the unique differentiation of the Earth (e.g., formation of granitic continental crust and hydrothermal ore deposits). However, how water actually interacts with the rocks and circulates within the solid Earth to contribute to material differentiation and dynamics has been poorly constrained. In this paper, we present numerical models of water and element transport in subduction zones, as well as global geochemical evidences for water and the associated element cycling in the mantle. Then we compare these geochemical evidences with the geophysical observations and modeling to propose “top-down hemispherical dynamics” for the whole Earth’s interior.
Japan Geoscience Union, 2015
I present a forward model perspective on the behavior of water mixed with major and trace element... more I present a forward model perspective on the behavior of water mixed with major and trace elements in the slab fluxes and in the magmas from subduction zones. Arc Basalt Simulator version 4 (ABS4: Kimura J.-I. et al. (2014) Diverse magmatic effects of subducting a hot slab in SW Japan: results from forward modeling. G3, doi:10.1002/2013GC005132) is a forward model calculating element mass balance in the slab dehydration/melting and melting of the wedge mantle peridotite by fluxing of the slab fluid/melt to estimate element abundances in the primary arc magmas, such as basalt, high-Mg andesite, and adakite. Mass balance of water is considered together with major and trace elements, and Sr-Nd-Hf-Pb isotopes in the numerical model. Once element mass balance between the source materials (slab sediment, altered oceanic crust, and peridotite, and mantle wedge peridotite) and a primary arc magma is established, source conditions including (1) depth of the slab dehydration/melting, (2) cont...
Japan Geoscience Union, 2016
Geochemistry, Geophysics, Geosystems, 2020
Volcanoes in the East Asian/Pacific region have been the source of some of the largest magnitude ... more Volcanoes in the East Asian/Pacific region have been the source of some of the largest magnitude eruptions during the Late Quaternary, and accurately evaluating their eruptive histories is essential for hazard assessments. To overcome difficulties in resolving and precisely dating eruptions in the near‐source realm, the high‐resolution (varved) sediments of Lake Suigetsu (central Honshu, Japan) were examined for the presence of non‐visible (cryptotephra) layers from 50 ka up until the 30 ka Aira‐Tanzawa (AT) caldera‐forming event of Aira volcano. Cryptotephra layers are four times more frequently preserved than visible markers in the Suigetsu sediments, meaning that this archive provides a unique and unprecedented record of eruptions that were dispersed over the densely populated regions of central Honshu. Major and trace element volcanic glass chemistry is used to fingerprint the ash layers and pinpoint their volcanic origin. Tephras are found throughout the investigated sediments,...
Journal of Volcanology and Geothermal Research, 2019
The eruptive histories of Ulleungdo (South Korea) and Changbaishan (North Korea/China border) vol... more The eruptive histories of Ulleungdo (South Korea) and Changbaishan (North Korea/China border) volcanoes are not well constrained since their proximal stratigraphies are poorly exposed or largely inaccessible. However, determining the past behaviour of these volcanoes is critical since future eruptions are likely to disperse ash over some of the world's largest metropolitan regions. Alkaline tephra deposits erupted from both centres are routinely identified in marine cores extracted from the Sea of Japan, as well as high-resolution lacustrine records east of the volcanoes. Here, we review the distal ash occurrences derived from Ulleungdo and Changbaishan and provide new data from the Lake Suigetsu (central Honshu, Japan) sediment core, in order to provide a more complete and constrained eruption framework. The intensely-dated Lake Suigetsu archive provides one of the most comprehensive distal eruption records for both centres, despite being located ca. 500 km E of Ulleungdo and ca. 1000 km SSE of Changbaishan. The Suigetsu record is utilised to precisely date and geochemically fingerprint (using major, minor and trace element glass compositions) ash fall events that reached central Honshu. Here, we identify a new non-visible (cryptotephra) layer in the Suigetsu sediments, which reveals a previously unreported explosive event from Changbaishan at 42,750-42,323 IntCal13 yrs BP (95.4 % confidence interval). This event is chronologically and geochemically distinct from the B-J (Baegdusan-Japan Basin) tephra reported in the Sea of Japan (ca. 50 ka). Furthermore, we also confirm that the widespread U-Ym tephra erupted from Ulleungdo reached central Japan, and is herein dated to 40,332-39,816 IntCal13 yrs BP (95.4 % confidence interval). This terrestrial 14 C-derived age of the U-Ym can be used to constrain the chronology of marine records containing the same marker layer. This reviewed and integrated tephrostratigraphic framework highlights the pivotal role that distal sedimentary records can play in evaluating the eruptive histories and hazard potential of Ulleungdo and Changbaishan.
GEOCHEMICAL JOURNAL, 2018
proved by using femtosecond laser ablation (FsLA; Kimura and Chang, 2012) and a multiple Faraday ... more proved by using femtosecond laser ablation (FsLA; Kimura and Chang, 2012) and a multiple Faraday collector (MFC) equipped with high-gain Faraday amplifiers using a 10 13 W resistor. The latter increases the signal/ noise ratio of the target isotopes by ten times for a few ppm Pb compared with using a conventional 10 11 W resistor, which enables one to determine the 206 Pb-based isotope ratios at a spatial resolution of a few tens of micrometers. It is difficult to analyze 204 Pb-based isotope ratios because the peaks of 204 Hg and 204 Pb overlap, which causes the analytical precision of 204 Pb to deteriorate (Kimura et al., 2016). Here, we report the preliminary results of a high-precision microanalysis of Pb isotopes in olivine-hosted melt inclusions from Rarotonga Island by FsLA-MFC-ICP-MS. The reduced analytical area enabled the combined use of FsLA-sector field (SF)-ICP-MS for further analysis of major and trace elements from the same melt inclusions. SAMPLES We analyzed two olivine-hosted melt inclusions recovered from enriched mantle EM1-type ocean island
GEOCHEMICAL JOURNAL, 2014
rials, such as silicate glass and magmatic melt inclusions, especially for analyses where high sp... more rials, such as silicate glass and magmatic melt inclusions, especially for analyses where high spatial resolution is desired. High spatial resolution capability, for instance, down to 20-30-µm diameter, is required in applications of olivine melt inclusion analysis (e.g., Saal et al. (2005) by secondary ion mass spectrometry (SIMS), and Paul et al. (2011) by LA-MC-ICP-MS). The incorporation of ion counters (ICs) into mass spectrometry is a recent advancement that extends LA-MC-ICP-MS for Pb isotope analysis, because analysis with an extremely small ion beam is commonly required owing to the restrictions of small sampling volume and low Pb content (e.g., <10 ppm). In many previous studies, one to a few ICs have been combined with Faraday collectors (FCs). However, only minor isotope 204 Pb and interfering mercury signals were usually monitored by the ICs, while the major isotopes of Pb (206,207,208 Pb) and 203,205 Tl (for mass bias correction) were measured by the FCs (e.g., Kent and Dilles, 2005; Paul et al., 2011). When different types of detectors are employed, their cross calibration is crucial for a precise and accu
GEOCHEMICAL JOURNAL, 2015
Os isotope compositions in ferromanganese crusts (Fe-Mn crusts) have been used for the dating of ... more Os isotope compositions in ferromanganese crusts (Fe-Mn crusts) have been used for the dating of model ages from present to the Late Cretaceous. This dating method assumes that the Fe-Mn crusts preserve a paleo-seawater Os isotope composition at the timing of Fe-Mn crust deposition. However, available Os isotope data are limited to dredged samples without precise indications of water depths, and the Os isotope variation in relation to water depth remains uncertain. Here, we report on the Os isotope ratio data in the surface layer of Fe-Mn crusts from 956-2987 meters below sea level at the Takuyo Daigo Seamount in the northwestern Pacific Ocean collected by a remotely operated vehicle (ROV). Since the 187 Re/ 188 Os ratios of the surface layer samples exhibited low values ranging from 0.020 to 0.0078, the age correction of the 187 Os/ 188 Os ratios by subtracting radiogenic 187 Os from total 187 Os was not necessary for the Takuyo Daigo Fe-Mn crusts. Regardless of water depth, the surface layer samples possessed a narrow range of 187 Os/ 188 Os ratio (1.003-1.017). As their Os isotope ratios were very similar to or slightly lower than the present-day seawater value (~1.06), the Fe-Mn crusts are inferred to preserve the modern seawater Os isotope composition at the investigated water depths. Therefore, Os isotope stratigraphy using Fe-Mn crusts is a powerful dating tool in paleoceanography.
Au-Cu-Mo deposits represent major metal resources known to be spatially and temporally associated... more Au-Cu-Mo deposits represent major metal resources known to be spatially and temporally associated with intrusive arc magmatism and, according to some studies, notably with adakites. Although the bulk of the ore metals seems to originate from the magmas, there is as yet no consensus on processes responsible for their concentration. The fact that primary ore minerals are predominantly sulfides has led to the suggestion that sulfur may play an important role in metal enrichment processes at the magmatic stage. Besides, although no previous study has focused so far on its pressure-dependency, the solubility of gold in silicate melts is expected to vary with depth in a significant way, independently of any fractionation process. If this is true, it may lead to important implications for the gold budget of arc magmas rising up through the mantle wedge and the crust. In addition to recently published gold solubility data at 1000°C and 0.4 GPa (Jego et al., 2010, GCA, In press), we present ...
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Papers by Jun-Ichi Kimura