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Journal Articles

Solidification pressures and ages recorded in mafic microgranular enclaves and their host granite; An Example of the world's youngest Kurobegawa granite

Suzuki, Kota*; Kawakami, Tetsuo*; Sueoka, Shigeru; Yamazaki, Ayu*; Kagami, Saya; Yokoyama, Tatsunori; Tagami, Takahiro*

Island Arc, 31(1), p.e12462_1 - e12462_15, 2022/09

 Times Cited Count:1 Percentile:33.39(Geosciences, Multidisciplinary)

Journal Articles

Microbial influences on manganese deposit formation at Yunotaki Fall, Japan

Shiraishi, Fumito*; Chihara, Ryoji*; Tanimoto, Risa*; Tanaka, Kazuya; Takahashi, Yoshio*

Island Arc, 31(1), p.e12448_1 - e12448_9, 2022/05

 Times Cited Count:0 Percentile:0(Geosciences, Multidisciplinary)

At Yunotaki Fall in north Japan, manganese-oxidizing bacteria were previously assumed to have oxidized manganese to precipitate birnessite, which relied on oxygen released from algae. However, it remained unclear whether larger-scale manganese oxide precipitation was actually occurring under light conditions. This study evaluated the contribution of indirect oxidation using microelectrodes to analyze local water chemistry, in addition to bulk water chemistry and DNA analyses. The results of this study demonstrate that low bulk pH values in the hot spring water hindered indirect oxidation despite the occurrence of active oxygenic photosynthesis and that direct oxidation by manganese-oxidizing bacteria is considered to dominate in the investigated sample.

Journal Articles

U-Pb ages of zircons from metamorphic rocks in the upper sequence of the Hidaka metamorphic belt, Hokkaido, Japan; Identification of two metamorphic events and implications for regional tectonics

Takahashi, Yutaka*; Mikoshiba, Masumi*; Shimura, Toshiaki*; Nagata, Mitsuhiro; Iwano, Hideki*; Danhara, Toru*; Hirata, Takafumi*

Island Arc, 30(1), p.e12393_1 - e12393_15, 2021/01

 Times Cited Count:2 Percentile:24.36(Geosciences, Multidisciplinary)

The Hidaka metamorphic belt is an excellent example of island-arc-type crust, and in this belt the metamorphic grade increases westwards from unmetamorphosed sediment up to the granulite facies. The metamorphic age of the belt had previously been considered to be ca. 55 Ma. However, zircons from the granulites in the lower sequence have given U-Pb ages of ca. 21-19 Ma and a preliminary report on zircons from pelitic gneiss in the upper sequence gave a U-Pb age of ca. 40 Ma. In this paper we provide new U-Pb ages for zircons from the pelitic gneisses in the upper sequence in order to assess the metamorphic age and also the maximum depositional age of the sedimentary protolith. The weighted mean $$^{206}$$Pb/$$^{238}$$U ages and 2 sigma errors for zircons from biotite gneiss in the central area of the belt are 39.6 $$pm$$ 0.9 Ma for metamorphic overgrowth rims and 53.1 $$pm$$ 0.9 Ma for the youngest inherited detrital cores. The ages of zircons from cordierite-biotite gneiss in the southern area are 35.9 $$pm$$ 0.7 Ma for overgrowth rims and 46.5 $$pm$$ 2.8 Ma for the youngest detrital cores. These results indicate that the metamorphism of the upper sequence took place at ca. 40-36 Ma, and that the sedimentary protolith was deposited after ca. 53-47 Ma. These metamorphic ages are consistent with the reported ages of ca. 37-36 Ma plutonic rocks in the upper sequence, but contrast with the ca. 21-19 Ma ages of metamorphic and plutonic rocks in the lower sequence. Therefore, we conclude, that the upper and lower metamorphic sequences developed independently but became coupled before ca. 19 Ma as a result of dextral reverse tectonic movements, as indicated by the intrusion of ca. 19-18 Ma magmas, possibly generated in the lower sequence, into the upper sequence.

Journal Articles

Solidification depth and crystallization age of the Shiaidani Granodiorite; Constraints to the average denudation rate of the Hida Range, central Japan

Kawakami, Tetsuo*; Sueoka, Shigeru; Yokoyama, Tatsunori; Kagami, Saya; King, G. E.*; Herman, F.*; Tsukamoto, Sumiko*; Tagami, Takahiro*

Island Arc, 30(1), p.e12414_1 - e12414_11, 2021/01

 Times Cited Count:4 Percentile:36.3(Geosciences, Multidisciplinary)

Journal Articles

Seismic subsidence near the source region of the 1662 Kanbun Hyuganada Sea earthquake; Geochemical, stratigraphical, chronological, and paleontological evidences in Miyazaki Plain, southwest Japan

Niwa, Masakazu; Kamataki, Takanobu*; Kurosawa, Hideki*; Kokubu, Yoko; Ikuta, Masafumi*

Island Arc, 29(1), p.e12341_1 - e12341_26, 2020/01

 Times Cited Count:4 Percentile:23.66(Geosciences, Multidisciplinary)

Based on detailed geochemical and paleontological analyses for lowland sediments in the Miyazaki Plain, southwest Japan, we clearly identified environmental change from the lower terrestrial sediments to the upper shallow marine sediments. Radiocarbon ages and tephra data suggest that the environmental change is attributed to local subsidence due to the 1662 Kanbun Hyuganada Sea Earthquake shown in historical records. This findings are important for historical earthquake studies because the study area is a part of the expected focal region of megathrust earthquakes along the Nankai Trough.

Journal Articles

Low-temperature thermochronological database of bedrock in the Japanese Islands

Sueoka, Shigeru; Tagami, Takahiro*

Island Arc, 28(4), p.e12305_1 - e12305_8, 2019/07

 Times Cited Count:1 Percentile:6.04(Geosciences, Multidisciplinary)

no abstracts in English

Journal Articles

Provenance identification based on EPMA analyses of heavy minerals; Case study of the Toki Sand and Gravel Formation, central Japan

Shimizu, Mayuko; Sano, Naomi; Ueki, Tadamasa; Komatsu, Tetsuya; Yasue, Kenichi*; Niwa, Masakazu

Island Arc, 28(2), p.e12295_1 - e12295_13, 2019/03

 Times Cited Count:3 Percentile:17.65(Geosciences, Multidisciplinary)

no abstracts in English

Journal Articles

Spatial distribution of the apatite fission-track ages in the Toki granite, central Japan; Exhumation rate of a Cretaceous pluton emplaced in the East Asian continental margin

Yuguchi, Takashi*; Sueoka, Shigeru; Iwano, Hideki*; Danhara, Toru*; Ishibashi, Masayuki; Sasao, Eiji; Nishiyama, Tadao*

Island Arc, 26(6), p.e12219_1 - e12219_15, 2017/11

 Times Cited Count:11 Percentile:42.51(Geosciences, Multidisciplinary)

The spatial distribution of AFT age in the granitic body is a favorable key to reveal a cooling behavior of the whole pluton. The cooling behavior is attributable to the regional exhumation of the Toki granite related to the regional denudation of the Tono district. Combination of the AERs and AFT inverse model applying to the granite is a powerful procedure for evaluating the cooling and exhumation history of the granitic pluton and thus denudation history of the tectonic region that surrounded the rock body.

Journal Articles

Petrographic study of the Miocene Mizunami Group, Central Japan; Detection of unrecognized volcanic activity in the Setouchi Province

Sasao, Eiji

Island Arc, 22(2), p.170 - 184, 2013/06

 Times Cited Count:5 Percentile:15.86(Geosciences, Multidisciplinary)

Petrographic study of sandstones from the Miocene Mizunami Group distributed in Central Japan has been performed using core from a single borehole to evaluate the provenance of the sedimentary rock. Sandstones studied are divisible into three types based mainly on their heavy mineral and plagioclase compositions; one type is characterized by biotite and plagioclase in the range from albite to oligoclase, the second is characterized by dominance of amphibole and labradorite, and the third type is characterized by dominance of pyroxene and andesine with lesser labradorite, bytownite and anorthite. The first type was derived from basement granite whereas the others were derived mostly from volcanic ash. The volcanic activity, which supplied the volcanic ash to the Mizunami sedimentary basin, occurred in two phases, distinguishable by variations in mineralogical and geochemical compositions. This is an indication of change in the character of the volcanic activity.

Journal Articles

Reconstructing the evolution of fault zone architecture; Field-based study of the core region of the Atera Fault, Central Japan

Niwa, Masakazu; Mizuochi, Yukihiro*; Tanase, Atsushi*

Island Arc, 18(4), p.577 - 598, 2009/12

 Times Cited Count:12 Percentile:9.83(Geosciences, Multidisciplinary)

Architecture of fault/crush zones and their development histories are closely linked to the long-term stability of the underground environment. Herein, we studied part of the Atera Fault System, one of several large, active faults in Central Japan, and described the detailed mesoscopic and microscopic features of a crush zone to reveal its development at higher structural levels of the fault (i.e. several hundred meters to kilometers in depth). The zone is characterized by brittle fracturing and rock mass pulverization, lacks both ultracataclasite bands and any deformation structures showing pressure solution. The characteristics of the deformation structures suggest that the exposed crush zone was formed at a depth of less than several kilometers. Features of clay mineral and carbonate precipitations in the zone indicate the repetition of intense fragmentation and shear localization through periodic activities on the Atera Fault after the Pleistocene.

Journal Articles

${it In situ}$ hydraulic tests in the active fault survey tunnel, Kamioka mine, excavated through the active Mozumi-Sukenobe fault zone and their hydrogeological significance

Nohara, Tsuyoshi; Tanaka, Hidemi*; Watanabe, Kunio*; Furukawa, Noboru*; Takami, Akira*

Island Arc, 15(4), p.537 - 545, 2006/12

 Times Cited Count:4 Percentile:11.06(Geosciences, Multidisciplinary)

The spatial hydrogeological and structural character of the active Mozumi-Sukenobu Fault (MSF) was investigated along a survey tunnel excavated through the MSF in the Kamioka Mine, Central Japan. Major groundwater conduits on both sides of the MSF are recognized. One is considered to be a sub-vertical conduit between the tunnel and the surface, the other is estimated to be a major reservoir of old meteoric water alongside the MSF. Studies indicate that part of the MSF is a sub-vertical continuous barrier that obstructs younger meteoric water observed in the southeastern part of the Active Fault Survey Tunnel (AFST) and recharge to the rock mass intersected by the northwestern part of the AFST. It is considered that the MSF is a continuous barrier resulting in the storage of a large quantity of older groundwater to the northwest. The observations indicate that the major reservoir is not the fault breccia associated with the NE-SW oriented faults of the MSF. Rather, the reservoir is considered to be the zone in which blocks of fractured rocks occur beside high angle faults corresponding to X shears that coincide in orientation with the present-day regional stress field and antithetic Riedel shears of the MSF. It is considered that secondary porosity is developed in the major reservoir by the destruction of filling minerals and fracture development beside these shears. The results of borehole investigations in the AFST indicate that increase in hydraulic conductivity is not directly related to increased density of fractures around the MSF. Our results suggested that minor conduits are sporadically distributed in the sedimentary rocks around the MSF in the AFST.

Journal Articles

Integrated description of deformation modes in a sedimentary basin; A Case study around a shallow drilling site in the Mizunami area, eastern part of southwest Japan

Ito, Yasuto*; Amano, Kenji; Kumazaki, Naoki*

Island Arc, 15(1), p.165 - 177, 2006/03

 Times Cited Count:3 Percentile:11.06(Geosciences, Multidisciplinary)

Tectonic episodes in a sedimentary basin are described on the basis of an integrated study combining reflection seismic interpretation, drilling survey and paleomagnetism. A shallow inclined borehole penetrated a fault shown by reflection seismic and geological surveys in the Mizunami area, the eastern part of southwest Japan. Paleomagnetic measurements were executed on core samples successfully oriented using side-wall image logging of structural attitude. At six horizons, we confirmed stable characteristic remanent magnetization (ChRM) through thermal and alternating field demagnetization tests, which is carried by magnetite with minor amount of high coercivity minerals as revealed by experiment of stepwise acquisition of isothermal remanent magnetization. After correction of multi-phase deformation inferred from borehole structural analysis, ChRM directions are combined with previous data and confirm easterly deflection reflecting coherent clockwise rotation of the arc before the Middle Miocene. Compilation of reliable paleomagnetic data describes differential rotation of the eastern part of southwest Japan raised by collision of the Izu-Bonin arc since the Middle Miocene.

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