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Intermittent hydrothermal alteration and silicification of black mudstones found in the Middle to Upper Miocene Yagen Formation, Shimokita Peninsula, Northeast Japan Isl. Arc (IF 1.5) Pub Date : 2024-03-11 Hirokazu Ueda, Yoshikazu Sampei
Organic geochemical processes in hydrothermal alteration system in terrestrial areas were investigated in the Shimofuro geothermal field, Northeast Japan. This study describes a continuous long mudstone outcrop of the Middle to Late Miocene Yagen Formation on the Shimokita Peninsula, Aomori Prefecture. The outcrop located near Mt.Hiuchi‐dake shows sequential alteration with a color change from black
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Apatite U–Pb geochronology and whole rock, Sr–Nd–Pb isotopic geochemistry of XV mafic-ultramafic intrusion, Bafq, Central Iran: Implications for petrogenesis and tectonic setting Isl. Arc (IF 1.5) Pub Date : 2024-02-17 Sakine Amraei, Mohammad Yazdi, Liang Qiu, Chang-Zhi Wu, Lei Chen, Bertrand Moine, Majid Ghasemi Siani, Qihui Zhang, Shahrokh Rajabpour
The XV mafic-ultramafic intrusion is located in the western part of the Posht-e-Badam Block (PBB) within the Central Iranian Micro-Continent (CIMC). Petrographically, the intrusion is composed of gabbro and pyroxenite. Apatite U–Pb dating has established the crystallization age of this intrusion to be 363 ± 67 Ma. The XV intrusive rocks are tholeiitic to slightly calc-alkaline in nature and are characterized
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Delineation of an exhumed intermediate-depth crustal fault in a collisional setting: An example from the Himalaya Isl. Arc (IF 1.5) Pub Date : 2024-02-16 Dyuti Prakash Sarkar, Jun-ichi Ando, Kaushik Das, Gautam Ghosh
The regionally prominent main boundary thrust (MBT) of the Himalayan fold-thrust belt in northwest India is typically defined by the presence of Proterozoic rocks in the hanging wall and Cenozoic rocks in the footwall. The present study focuses on identifying the MBT contact across Gambar River section in Himachal Pradesh, India, using alternative methodologies, such as the meter-scale litho-structural
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Investigating the impact of sample desiccation on Itrax XRF core scanner signal reproducibility Isl. Arc (IF 1.5) Pub Date : 2024-02-20 Naveed Hassan, Ludvig Löwemark, Alice Chien‐Yi Liao
Sediment samples tend to dry out during storage and are, therefore, stored refrigerated at about 4°C after wrapping in plastic foil. During XRF core scanning however, the samples must be taken out of their cover, increasing the risk of drying and formation of desiccation cracks on the surface. Because scan times can often amount to several hours and at highest resolution may take over a day to complete
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Field-based description of near-surface crustal deformation in a high-strain shear zone: A case study in southern Kyushu, Japan Isl. Arc (IF 1.5) Pub Date : 2024-02-13 Masakazu Niwa, Koji Shimada, Shuji Terusawa, Akira Goto, Nariaki Nishiyama, Toru Nakajima, Takanori Ishihara, Hiroaki Hakoiwa
This study investigated geological evidence for near-surface crustal deformation in a high-strain shear zone that has been geodetically identified but which is not associated with obvious tectonic landforms. Fieldwork was conducted in the east–west-trending southern Kyushu high-strain shear zone (SKHZ), Japan, focusing mainly on occurrences of fracture zones, which are defined by a visible fracture
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Magnetostratigraphic dating of Early Miocene deep-sea fossils from the Morozaki Group in central Japan Isl. Arc (IF 1.5) Pub Date : 2024-01-29 Hiroyuki Hoshi, Akari Matsunaga
Early Miocene sediments of the Morozaki Group in central Japan contain deep-sea fossils that have been dated using biostratigraphic and radiometric data. In this study, we utilize magnetostratigraphy to provide a more precise age for mudstones from just below the layer containing the fossils. Rock magnetic experiments suggest that both magnetic iron sulfide and Ti-poor titanomagnetite carry the remanent
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Rhuddanian to Aeronian (Llandovery, early Silurian) carbon isotope stratigraphy throughout carbonate sequences in the upper Yangtze region, South China block Isl. Arc (IF 1.5) Pub Date : 2024-01-23 Shenyang Yu, Qijian Li, Stephen Kershaw, Axel Munnecke, Yingyan Mao, Yue Li
The Xiangshuyuan Formation (middle Rhuddanian to middle Aeronian stages of the Llandovery Series, lower Silurian) records a shelly fauna representing recovery after the end-Ordovician mass extinction in a well-oxygenated shallow carbonate platform of the Upper Yangtze region, South China Block. Carbon isotope stratigraphy is documented from limestone sequences of the formation at the Qiankou section
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Indosinian anatexis of Paleoproterozoic granites in the east Cathaysia Block, South China Isl. Arc (IF 1.5) Pub Date : 2024-01-19 Wei Zhang, Hanwen Zhou, Xiaohua Zhou, Xilin Zhao, Huan Liu, Yang Jiang, Chunzhong Li
Granulite facies metamorphism and crustal anatexis exist in the East Cathaysia Block, the exact timing of granulite facies partial melting and its link with orogenesis have not been well constrained. In this study, we carried out petrography, whole rock geochemistry, and zircon U–Pb dating, trace elements and Hf isotopes analyses on Dazhe gneissic granite and banded migmatite from the Badu Group in
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Eocene extensional tectonics in the Amakusa region, northern Ryukyu arc Isl. Arc (IF 1.5) Pub Date : 2024-01-11 Kentaro Ushimaru, Atsushi Yamaji
Paleogene surface tectonics in Japan is not well understood because of the paucity of onshore Paleogene stratigraphic records except for those from accretionary complexes. Paralic Paleogene formations remaining in SW Japan are usually so thin that it is difficult to decipher the tectonics from them. However, the Eocene paralic sedimentary package with a thickness of kilometers indicates syn-depositional
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Magmatic processes forming replacement textures with fluorite alignments in feldspars in an evolved trachyte from Oki-Dogo Island, Sea of Japan Isl. Arc (IF 1.5) Pub Date : 2024-01-08 Satoshi Nakano, Kuniaki Makino
Internal microtextures of ternary alkali feldspars in sanidine trachyte from Oki-Dogo Island were examined using an electron microprobe analyzer, a scanning electron microscope, a transmission electron microscope and cathodoluminescence instruments, to develop the understanding of volcanic processes of alkaline magmas related to feldspar crystallization. The examined trachyte is an evolved rock of
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Small half-graben inferred from a Miocene syn-rift succession in the Kinbusan area, eastern Tottori prefecture, Japan Isl. Arc (IF 1.5) Pub Date : 2023-12-28 Toshiki Haji
Understanding the Miocene tectonics of the southwest Japan Arc is key to elucidating the history of the opening of the Japan Sea, and important advances have been made in the last 10 years, such as clarification of the timing of arc rotation. Syn-rift successions occur in the eastern San'in basins, but they have received little attention because the basic stratigraphy and development of the basins
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Rock magnetic analyses as a tool to investigate diversity of drift pumice clasts: An example from Japan's 2021 Fukutoku-Oka-no-Ba (FOB) eruption Isl. Arc (IF 1.5) Pub Date : 2023-12-28 Julie Carlut, Aude Isambert, Claire Carvallo, Geoffrey Garcia da Fonseca, Nelly-Wangue Moussissa, Arthur Bouis, Kenta Yoshida
The crystallization of nanolites within magma chambers has recently raised a strong interest due to their impact on increasing melt viscosity and triggering magmatic eruptions. In 2021, the Fukutoku-Oka-no-Ba (FOB) underwater eruption produced large quantities of pumices that eventually formed rafts drifting at the surface of the ocean to the East coasts of Japan. Pumices collected along the shore
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Geochronological and petrological investigations of Miocene felsic igneous rocks in the Amakusa Islands, southwest Japan: Possible extension of the Setouchi Volcanic Belt Isl. Arc (IF 1.5) Pub Date : 2023-12-28 Hironao Shinjoe, Yuji Orihashi, Mana Akasaka, Sota Niki, Minoru Sasaki, Takafumi Hirata
The opening of the Japan Sea led to the separation of southwest Japan from the Eurasian continent. Subsequent to this event, a diverse range of igneous activities occurred in southwest Japan. On the back-arc side of the region, igneous activity commenced at approximately 22 Ma and persisted for an extended period. In the trench-proximal region of southwest Japan, magmatism initiated around 15.6 Ma
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Sulfur-rich mafic magma injection into the felsic magma chamber beneath Asama volcano, central Japan: Records in olivine-hosted melt inclusions from the Itabana and Tenmei eruptions Isl. Arc (IF 1.5) Pub Date : 2023-11-20 Yoshiaki Yamaguchi, Andreas Auer, Isoji Miyagi
Even though no basalts have erupted at Asama volcano, its large, felsic magma chamber standing beneath the summit is frequently replenished by cryptic injections of mafic magma of basalt-basaltic andesite composition. This mafic magma is preserved within melt inclusions trapped in olivine phenocrysts collected from the old Itabana pumice of the Kurofu stage and the Tenmei pumice of the current Maekake
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X-ray computed tomography of deep-sea clay as tools to detect rare earth elements and yttrium enrichment Isl. Arc (IF 1.5) Pub Date : 2023-10-24 Yoichi Usui, Kazutaka Yasukawa, Koichi Iijima, Hideaki Machiyama, Yuji Ichiyama, Erika Tanaka, Koichiro Fujinaga
Pelagic clay that contains rare-earth elements and yttrium (REY) at over 2000 ppm (termed “highly REY-rich mud”) has been reported from a few areas in the western North Pacific Ocean through focused geochemical analyses. Those REY are carried by biogenic calcium phosphate, suggesting that the formation of highly REY-rich mud involves enhanced biological productivity. However, detecting REY enrichment
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Topography, sedimentology, and biochronology of carbonate deposits on seamounts in the JA area, northwestern Pacific Ocean Isl. Arc (IF 1.5) Pub Date : 2023-09-24 Yasufumi Iryu, Hikari Hino, Hideko Takayanagi, Tokiyuki Sato, Nobuyuki Okamoto, Akiko Suzuki, Yuho Fujimaki, Akira Usui
Sedimentological and biochronological analyses were undertaken on carbonate deposits from 20 seamounts belonging to the Marcus–Wake Seamount Group, the Magellan Seamounts, and the Marshall Islands Seamounts in the JA area, northwestern Pacific Ocean. Deposition of carbonates on the JA seamounts varied markedly with age. The oldest carbonate deposits are Lower to middle Cretaceous shallow-water limestones
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Late Cretaceous–Paleogene terrestrial sequence in the northern Kitakami Mountains, Northeast Japan: Depositional ages, clay mineral contents, and vitrinite reflectance Isl. Arc (IF 1.5) Pub Date : 2023-09-22 Atsushi Noda, Kazuya Morimoto, Koji U. Takahashi, Tohru Danhara, Hideki Iwano, Takafumi Hirata
Forearc basin deposits on continental margins contain important information that can be used to reconstruct the tectonic setting, volcanism, and climate at the time of their deposition. Coal-bearing terrestrial to shallow marine strata in Northeast Japan were deposited in a forearc basin along the Eurasian continental margin during the Cretaceous–Paleogene. The rocks exposed in the Kado district, Iwate
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Simulation of methane hydrate formation in coarse- to fine-grained sediments in the Nankai Trough, Japan Isl. Arc (IF 1.5) Pub Date : 2023-09-19 Chao Xu, Hitoshi Tomaru
The properties of host sediments and pore water considerably affect both the occurrence and formation processes of methane hydrate. In coarse-grained layers, hydrates are generally concentrated preferentially in the pore space, and their formation is influenced by pore water salinity. To understand how geophysical and geochemical factors control the distribution of methane hydrates, we conducted numerical
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Role of mantle carbonation in trench outer-rise region in the global carbon cycle Isl. Arc (IF 1.5) Pub Date : 2023-09-04 Ikuo Katayama, Keishi Okazaki, Atsushi Okamoto
A nearly balanced carbon budget between subduction input and degassing output has likely controlled the long-term surface environment and habitability of Earth throughout geological history. However, the ongoing extensive hydration and carbonation of the mantle in trench outer-rise regions may affect the global carbon budget. In this study, we show that the carbon content of the lithospheric mantle
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The proximal volcaniclastic materials of Fukutoku-Oka-no-Ba in the Izu-Bonin arc show contrasting characteristics to the drift pumice of the 2021 eruption Isl. Arc (IF 1.5) Pub Date : 2023-08-24 Kenta Yoshida, Yoshihiko Tamura, Tomoki Sato, Erika Tanaka, Noriko Tada, Morihisa Hamada, Takeshi Hanyu, Qing Chang, Shigeaki Ono
Fukutoku-Oka-no-Ba is a submarine volcano located at 24°17.1′ N/141°28.9′ E in the Izu–Bonin arc, and is one of the most active volcanoes in Japan. This volcano produced an explosive eruption in August 2021 that generated a large amount of volcaniclastic material, some of which drifted westward to Japan and the coastal area of East Asia as a pumice raft. The pumice clasts that drifted for >1000 km
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Metamorphic history of mafic granulite and garnet-bearing amphibolite from the Oki-Dogo Island, Japan Isl. Arc (IF 1.5) Pub Date : 2023-08-24 Mizuki Takahashi, Shunsuke Endo, Atsushi Kamei
Oki metamorphic rocks have long been considered as a constituent of the Hida Belt based on their geographic proximity, lithology, and Permo-Triassic metamorphism. However, recent geochronological studies have demonstrated that both para- and ortho-gneisses in the Oki-Dogo Island display Paleoproterozoic protolith formation and two separate phases of metamorphism at 1.85 Ga and 250–230 Ma. Consequently
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Complex factors contribute to the chemical composition of clastic sediments traveling from rivers to the ocean along island arcs: A case study of the Otsuchi area, Northeast Japan Isl. Arc (IF 1.5) Pub Date : 2023-08-24 Kei Sugiura, Hikaru Sawada, Mutsumi Iizuka, Mana Yasui, Qing Chang, Takafumi Kasaya
The chemical composition of coastal sediments and river sediments is influenced by the geological constitution of provenance and fractionation of clastic particles during sedimentary processes. The intricate nature of the geology in active subduction zones has complicated the comprehension of detrital sediments. More geochemical case studies in such areas are necessary to enhance the understanding
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Soft body reconstruction of a reptile fossil by the nondestructive elemental mapping with a newly designed XRF Isl. Arc (IF 1.5) Pub Date : 2023-08-16 Wei Wang, Ling Shu, Deqi Wang
Vertebrate fossils usually consist only of mineralized skeletons and rarely preserve soft body parts. However, the buried soft body releases the degraded material into the surrounding sediments. The degraded material can be preserved as invisible signals of some chemicals or authigenic minerals, which can be revealed by the elemental distribution of the fossils' surface and their surrounding rock.
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Geochronology and geochemistry of early Palaeozoic ultramafic rocks along Jiangshan-Shaoxing Fault and their tectonic significance Isl. Arc (IF 1.5) Pub Date : 2023-07-13 Cunzhi Wang, Zhizhong Huang, Qingbo Zhu, Guangfu Xing, Guodong Jin, Pingli Chu
The origins of early Paleozoic orogen in South China have two different models: subduction model and intra-continental model. Here we report two new identification of ~440 Ma arc-related ultramafic intrusions in Tingzifan (TZF) and Fomuting (FMT) along Jiangshan-Shaoxing fault (JSF) in South China, respectively. The Silurian ultramafic intrusions are composed of olivine pyroxenite, the SiO2, MgO and
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U–Pb and fission-track dating of Miocene hydrocarbon source rocks in the Akita Basin, Northeast Japan, and implications for the timing of paleoceanographic changes in the sea of Japan Isl. Arc (IF 1.5) Pub Date : 2023-07-13 Takeshi Nakajima, Hideki Iwano, Tohru Danhara, Takafumi Hirata, Kenta Asahina, Koji U. Takahashi, Yasuaki Hanamura
Middle to Late Miocene organic-rich siliceous mudstones (Onnagawa Formation) in the Akita Basin, Northeast Japan have been an important target for both paleoceanographic studies and hydrocarbon exploration in Japan. However, the reliable age of their formation has remained poorly constrained. Here, we report new zircon U–Pb and fission-track ages of the Onnagawa Formation from a previously well-studied
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Late Cretaceous tectono-magmatism of southeast China: Evidence from Qushandao Granite in the eastern Zhejiang province Isl. Arc (IF 1.5) Pub Date : 2023-07-10 Pingli Chu, Lang Bao, Zheng Duan, Minggang Yu, Yanhui Zhu
The Qushandao Granite, mainly composed of alkali-feldspar granite, is situated in the eastern Zhejiang province of coastal southeast China. In this paper, we present whole-rock geochemistry, zircon U–Pb geochronology, and Hf isotopes to constrain the age, magma sources, and geodynamic setting of the Qushandao Granite. LA-ICP-MS zircon U–Pb dating results revealed that the Qushandao Granite was emplaced
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Oxygen isotopes of the Japanese stalagmites as global and local paleoclimate proxies Isl. Arc (IF 1.5) Pub Date : 2023-07-05 Akihiro Kano, Hirokazu Kato, Akira Murata
Stalagmite oxygen isotopes (δ18O) have been used to reconstruct terrestrial paleoclimates during the late Pleistocene and Holocene. However, the interpretation of the δ18O is not straightforward when determining the factor controlling δ18O; temperature or water δ18O. In addition, the water δ18O changes with rainfall intensity (amount effect), rainfall seasonality, and some other factors. Here, we first
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Records of Nanhua island arc activity between the north and south Wuyi terranes in the Cathaysia Block Isl. Arc (IF 1.5) Pub Date : 2023-06-22 Huan Liu, Xilin Zhao, Jian Jiang, Jinguo Zhang
The characteristics and pre-Devonian tectonic evolution between the North and South Wuyi terranes are important for understanding the tectonic framework and aggregation of the micro-terrenes in the Cathaysia Block, as well as the evolution of the South China Block. This paper provides systematic studies on the petrologic features, zircon U–Pb geochronology and geochemical characteristics of the low-grade
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A trip into molten sulfur Isl. Arc (IF 1.5) Pub Date : 2023-06-19 Hikaru Sawada, Chong Chen, Hisanori Iwamoto, Ken Takai
Lakes of molten sulfur are features sometimes found in seafloor hydrothermal vent systems. Daikoku of the northern Mariana Arc is notable for being home to one of such features inside its summit caldera, the “Sulfur Cauldron” discovered in 2006. A number of oceanographic research cruises since then have revealed significant volcanic activities on Daikoku Seamount, including an eruption event in 2014
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Age, geochemistry, mineralization, and tectonic significance of felsic-intermediate dikes in Shuangqishan Au deposit, Cathaysia block, South China Isl. Arc (IF 1.5) Pub Date : 2023-06-06 Feipeng Fan, Fan Xiao, Yan Zhou, Shizhong Chen
The Shuangqishan Au deposit (>15 t) is located in the Dehua-Youxi-Yongtai goldfield of the southeastern Cathaysia Block, South China. There are three stages of granites in the Shuangqishan Au deposit, the pre-mineralization granite porphyry formed in the Middle Jurassic (~166.0 ± 0.8 Ma), the metallogenic granite porphyry and monzonite porphyry formed in the late stage of the Late Jurassic (153–151 Ma)
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Apatite U–Pb dating of dinosaur teeth from the Upper Cretaceous Nemegt Formation in the Gobi Desert, Mongolia: Contribution to depositional age constraints Isl. Arc (IF 1.5) Pub Date : 2023-05-31 Myu Tanabe, Kazumasa Aoki, Kentaro Chiba, Mototaka Saneyoshi, Shota Kodaira, Hirotsugu Nishido, Buuvei Mainbayar, Khishigjav Tsogtbaatar, Shinobu Ishigaki
The Nemegt Formation in the Gobi Desert, Mongolia, hosts abundant dinosaur and other vertebrate remains, the ages of which are uncertain due to a lack of radioactive dating. In order to more strictly constrain the depositional age of Nemegt Formation, we conducted U–Pb isotope, trace elements, and Y-screening analyses using laser-ablation inductively-coupled plasma-mass spectrometry (LA-ICP-MS) on
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Chronological and geochemical characteristics of metavolcanic rocks in the Nanping-Ninghua tectonic belt: Constraints on the formation of the Cathaysia block Isl. Arc (IF 1.5) Pub Date : 2023-05-09 Huicheng Wen, Xilin Zhao, Guocan Wang, Huan Liu, Mincheng Xu, Yang Jiang
The tectonic properties of the Nanping-Ninghua tectonic belt (NNTB) play a crucial role in understanding the tectonic evolution of the Wuyi orogenic belt, which is related to the Neoproterozoic-Paleozoic tectonic evolution of the Cathaysian Block. In this study, We present comprehensive petrological, geochronological, and geochemical data on the metavolcanic rocks from the Louqian Formation in Changting
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Elevated sedimentation of clastic matter in pelagic Panthalassa during the early Olenekian Isl. Arc (IF 1.5) Pub Date : 2023-05-05 Shun Muto, Satoshi Takahashi, Satoshi Yamakita
The end-Permian mass extinction is thought to have greatly altered biogeochemical cycles. The absence of chert and dominance of claystone in low-latitude pelagic deep-sea sedimentary sequences of Early Triassic Panthalassa (the deep-sea chert gap) has been believed to record radiolarian die-off and consequent decline in biogenic silica production. However, recent studies showed that the upper portion
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Granite rock towers shaped by mesh-like joint sets, which formed in the shallower portion of a granite body during cooling at depth Isl. Arc (IF 1.5) Pub Date : 2023-04-28 Masahiro Chigira, Hironori Kato
Granite is fractured according to the stress state during the cooling stage, providing predispositions for later topographic evolution. This study clarified that triangular mesh-like joints can be made during granite cooling and that they can become the structural causes for the formation of rock towers and corestones on the ground. Tengu rock, which consists of rock towers and granite corestones in
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Petrogenesis of mafic rocks from northwest Iran (Piranshahr) and comparison with northeast Iraq ophiolites: Implications for slab window magmatism in an evolving Neotethys arc Isl. Arc (IF 1.5) Pub Date : 2023-04-18 Maryam Yazdani, Mohssen Moazzen, Roland Oberhänsli
The Piranshahr ophiolite is located in northwest Iran. The Mawat ophiolite in northeast Iraq is the western continuation of the Piranshahr ophiolite. The whole rock geochemistry of mafic rocks from the Piranshahr ophiolite (in the Gerdikavalan regions) is studied and compared with mafic rocks from the Mawat ophiolite in northeast Iraq (in the Hasanbag, Walash and Naopurdan regions). Two groups can
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Early Paleozoic oceanic slab subduction in South China: Evidence from adakite-like granodiorite and high-Mg diorite from Puyang pluton in the Wuyi orogenic belt Isl. Arc (IF 1.5) Pub Date : 2023-04-12 Xiaodong Zhou, Tongchun Nie, Zhiding Han, Xilin Zhao
The mechanism of Caledonian orogeny in South China is still controversial. The main argument focuses on the issue that whether there existed oceanic subduction. To answer this question, the complex Puyang pluton in the central part of Wuyi orogenic belt was selected for zircon U–Pb dating, in-situ Lu–Hf isotopic analysis and geochemical testing. The Puyang pluton is mainly composed of granodiorite
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Zircon geochronology of the deformed matrix in the NE Jiangxi ophiolitic mélange belt: Time constraints on the Neoproterozoic evolution of the Paleo–South China Ocean and assembly of the Yangtze and Cathaysia blocks Isl. Arc (IF 1.5) Pub Date : 2023-03-21 Zhu Qingbo, Wang Cunzhi, Zhao Xilin, Jin Guodong, Gao Tianshan
The NE Jiangxi ophiolitic mélange belt is the key area for understanding the evolution of the Paleo-South China Ocean and the assembly of the Yangtze and Cathaysia blocks. The age of the deformed matrix is closer to the tectonic emplacement time of the ophiolitic mélange than that of the blocks. However, the rock types, ages and structural deformation of the matrix in the NE Jiangxi ophiolitic mélange
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Correction to Middle Holocene relative sea-level changes and vertical tectonic crustal movements on Shikoku Island near the Nankai Trough, Japan Isl. Arc (IF 1.5) Pub Date : 2023-02-08
Yamaguchi, T., Nanayama, F., Nakanishi, T., Tsuji, T., Ikeda, M., Kondo, Y., Miwa, M., & Hamada, Y. (2022). Middle Holocene relative sea-level changes and vertical tectonic crustal movements on Shikoku Island near the Nankai Trough, Japan. Island Arc, 31( 1), e12452. https://doi.org/10.1111/iar.12452 On page 9, third paragraph, the Dryad Digital Repository link (https://datadryad.org/stash/share/C
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Magnetic susceptibility, mineral chemistry, and geothermobarometry of granitoids from Lohit Plutonic Complex, Arunachal Trans-Himalaya, Northeast India: Implications on emplacement and crystallization conditions of oxidized calc alkaline magmatic arc system Isl. Arc (IF 1.5) Pub Date : 2023-02-02 Diezeneino Meyase, Vikoleno Rino, Santosh Kumar, Rokozono Nagi
The Lohit Plutonic Complex (LPC) of Arunachal Trans-Himalaya represents the northeast extension of Trans-Himalayan magmatic arc system located in the north of Indus Tsangpo Suture Zone (ITSZ). Field relation, magnetic susceptibility (MS), and phase petrology on the granitoids of LPC was conducted in order to assess the granite series (magnetite, oxidized vs. ilmenite, reduced types), and physico-chemical
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Hydrogeochemistry and geothermometry of the Ilgın geothermal field, Central Turkey Isl. Arc (IF 1.5) Pub Date : 2023-02-01 Ali Ferat Bayram
The Ilgın geothermal field that is the oldest and most important spa of the Konya Region is located in Central Turkey. The Ilgın geothermal field has five geothermal wells and three hot water springs with flow rates of 40–130 L/s, temperatures 26–42°C and depths of 120–300 m. In the present study, detailed hydrogeochemical investigations are carried out to understand the geothermal energy potential
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Fossil diatom assemblage changes due to paleoenvironment change, tsunami, and typhoon in southern Japan Isl. Arc (IF 1.5) Pub Date : 2023-01-16 Ara Cho, Kaoru Kashima, Hannah Baranes, Caroline Ladlow, Kota Katsuki, Jonathan D. Woodruff
Tracking paleoenvironmental change and past event deposits is very important to evaluate the natural hazard spatially. This paper presents how the environment changes and implies the event deposit depending on the diatom assemblage change. To investigate paleoenvironmental change and identify the difference between tsunami and typhoon deposits, we analyze diatoms from the sediments in two coastal lakes
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Late Triassic A-type granite boulders in Lower Cretaceous conglomerate of the Hida belt, Japan: Their origin and bearing on the Yamato tectonic line in Far East Asia Isl. Arc (IF 1.5) Pub Date : 2023-01-11 Yukio Isozaki, Yusuke Sawaki, Hideki Iwano, Takafumi Hirata, Keitaro Kunugiza
To identify the origin of the Hida belt in central Japan, geochemistry and U–Pb age of zircons were analyzed for the extra-large granitoid boulders in the Lower Cretaceous fluvial conglomerate of the Jinzu Group. This study clarified that the boulders of granitoids have geochemistry of typical A-type granite, as characterized by high Nb + Y and high Ta + Yb values. U–Pb ages of igneous zircons from
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Characteristics of crustal structures in the Yamato Basin, sea of Japan, deduced from seismic explorations Isl. Arc (IF 1.5) Pub Date : 2022-12-04 Takeshi Sato, Tetsuo No, Shuichi Kodaira
Crustal structures around the Yamato Basin in the southeastern Sea of Japan, inferred from recent ocean bottom seismography (OBS) and active-source seismological studies, are reviewed to elucidate various stages of crustal modification involved from rifting in the crust of the surrounding continental arc to the production of oceanic crust in the Yamato Basin of the back-arc basin. The northern, central
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Sedimentology and biostratigraphy of the upper Triassic carbonates from the Shiriya cape, North Kitakami Belt, Japan Isl. Arc (IF 1.5) Pub Date : 2022-11-16 Giovan Peyrotty, Andrea Fucelli, Camille Peybernes, Tetsuji Onoue, Hayato Ueda, Rossana Martini
Relics of the Panthalassa Ocean occur today in accretionary complexes and terranes on the entire Circum-Pacific region. Among them, remains of shallow-water carbonate systems provide valuable information about the ecology and environmental conditions that prevailed in this immense ocean. In this regard, the Shiriya Cape of the North Kitakami Belt (Aomori Prefecture, Honshu Island, Japan) is an essential
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Editorial for the thematic issue, “Orogens, ophiolites, and oceans: A snapshot of Earth's tectonic evolution” Isl. Arc (IF 1.5) Pub Date : 2022-11-04 Yasufumi Iryu, Tatsuki Tsujimori, Naoto Hirano, Yuji Ichiyama
1 INTRODUCTION Integrated studies of orogens, ophiolites, and oceans (OOO) provide a snapshot of Earth's dynamic evolution. As a key proxy of lithospheric plate underflow, the rocks in orogenic belts and oceans have been intensively studied from various scientific viewpoints and at different spatial–temporal scales. The rock record in OOO helps to better understand past plate-tectonic processes and
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Isochronline in chemostratigraphy for global correlation and an exception of the Walther's law of facies Isl. Arc (IF 1.5) Pub Date : 2022-10-30 Wei Wang
Chemostratigraphy based on various proxies has been well developed in recent decades for stratigraphic correlation by higher resolution, gap-less sampling, and environmental records. At present, various types of samples are measured quantitatively in higher accuracy and wider application than traditional biostratigraphy. Even the benthonic index fossils are widely replaced by pelagic data for biostratigraphic
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Post-collisional alkaline lamprophyre magmatism in northern Iran: Implications from whole-rock geochemistry and mineral compositions Isl. Arc (IF 1.5) Pub Date : 2022-10-21 Hadi Omrani, Christina Günter, Gholam Hossein Shamanian, Mehdi Omrani
The Shanderman lamprophyre dykes crop out in the western part of the Alborz Mountains (Talesh). These rocks are classified as camptonites, composed of primary olivine, Ti-rich diopside, kaersutite, biotite, plagioclase, K–feldspar, and minor Ti–rich spinels, magnetite, pentlandite–pyrrhotite/chalcopyrite, and powellite–scheelite. Secondary analcime–wairakite, serpentines, and prehnite are common minor
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An automatic peak deconvolution method for Raman spectra of terrestrial carbonaceous material for application to the geothermometers of Kouketsu et al. (2014) Isl. Arc (IF 1.5) Pub Date : 2022-10-19 Shunya Kaneki, Yui Kouketsu
Carbonaceous material undergoes changes in its maturity mainly in response to its thermal history. Among the various geothermometers based on Raman spectra of carbonaceous material, those proposed by Kouketsu et al. (2014) have been employed to investigate the temperatures experienced by terrestrial rocks that undergo low- to medium-grade metamorphism. Although their geothermometers use spectral parameters
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Zircon trace-element compositions in Miocene granitoids in Japan: Discrimination diagrams for zircons in M-, I-, S-, and A-type granites Isl. Arc (IF 1.5) Pub Date : 2022-10-12 Yusuke Sawaki, Hisashi Asanuma, Shuhei Sakata, Mariko Abe, Takeshi Ohno
Detrital zircons demonstrate high resistance to alteration and, as such retain information about their formation ages and parental magmas for a long period of time. Geochemical researchers have proposed a wide variety of discrimination diagrams applicable to detrital zircons. In our research, we focused on the conventional classification scheme for granites (Mantle, M; Igneous, I; Sedimentary, S; and
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The nature of the Moho beneath fast-spreading centers: Evidence from the Pacific plate and Oman ophiolite Isl. Arc (IF 1.5) Pub Date : 2022-09-21 Yoshihiko Tamura, Mathieu Rospabé, Gou Fujie, Akane Ohira, Kentaro Kaneda, Alexander R. L. Nichols, Georges Ceuleneer, Tomoki Sato, Shuichi Kodaira, Seiichi Miura, Eiichi Takazawa
It is common knowledge that the Moho is the boundary between the crust and the Earth's mantle. Here we show along several seismic profiles through the Pacific Plate that a correlation exists between the strength of Moho reflections, crustal thickness, and water depth. Where the Moho can be detected clearly, the overlying oceanic crust is systematically thicker and the water depths are shallower. We
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Petrogenesis of two types of gabbro from Neoproterozoic Fuchuan ophiolite complex, Jiangnan Orogen: Implication for a Japan Sea-like back-arc basin Isl. Arc (IF 1.5) Pub Date : 2022-09-15 Wentao Hong, Minggang Yu, Zhentao Song, Pingli Chu, Kai Liu, Xiaohua Zhou
The Neoproterozoic Fuchuan ophiolite complex (FCO) represents the lithospheric remnant of the back-arc basin in the southeastern margin of the Yangtze Craton. However, the nature and development of this back-arc system are still confusing. This study focuses on the tholeiitic gabbros in the FCO, which can be divided into enriched and depleted types according to their geochemical characteristics. Enriched
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Zircon U–Pb geochronology and geochemistry of the Late Jurassic granite porphyries from central-eastern Jilin Province, NE China: Petrogenesis and tectonic implications Isl. Arc (IF 1.5) Pub Date : 2022-09-13 Xiqing Ye, Zhitao Xu, Mengmeng Li, Liying Sun, Zhongwei Li, Donghan Yan, Jingqiao Feng
The recently discovered Yizuoying Mo deposit is located in central-eastern Jilin Province, NE China. The molybdenum (Mo) mineralization, mainly hosted in granite porphyry, is considered to be granite-related. Zircon U–Pb dating of the granite porphyry yielded concordant ages of 160.81 ± 0.62 Ma, which is consistent with the weighted mean U–Pb age of 160.53 ± 0.65 Ma, indicating that the emplacement
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Overprint of secondary Du folding in the Sambagawa metamorphic belt, SW Japan: Implications for strain ellipsoids and Paleogene tectonics of the east-Eurasian margin Isl. Arc (IF 1.5) Pub Date : 2022-09-13 Mutsuki Aoya
Two contrasting results of strain analyses, constriction and flattening, are recognized in the Sambagawa high-pressure/temperature metamorphic belt, SW Japan. An unverified proposal to account for this situation is that the constrictional strain ellipsoids develop only in areas where there is strong overprinting by a secondary Du-phase folding after a penetrative Ds-phase deformation. Field studies
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Solidification pressures and ages recorded in mafic microgranular enclaves and their host granite: An example of the world's youngest Kurobegawa granite Isl. Arc (IF 1.5) Pub Date : 2022-09-12 Kota Suzuki, Tetsuo Kawakami, Shigeru Sueoka, Ayu Yamazaki, Saya Kagami, Tatsunori Yokoyama, Takahiro Tagami
Solidification pressures and ages of mafic microgranular enclaves (MMEs) and their host granite were determined and compared based on Al-in-hornblende geobarometry and U–Pb zircon dating in two sample localities in the Kurobegawa Granite. In sample KRG19-A03 from the middle unit of the pluton, the MME and the host granite yielded 0.18 ± 0.03 to 0.24 ± 0.04 GPa and 0.16 ± 0.03 to 0.23 ± 0.04 GPa, respectively
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Autogenic and allogenic controls on the temporal palaeographic evolution of the Himalayan foreland basin: Insights from facies analysis of the lower Siwalik succession, Kumaun Himalaya, India Isl. Arc (IF 1.5) Pub Date : 2022-09-09 Pradeep K. Goswami, Karuna Singh
The lower Siwalik succession in the south-central Kumaun Himalaya records Middle Miocene fluvial sedimentation in the Himalayan foreland basin, the largest foreland basin of the world. Detailed facies analysis reveals three distinct facies associations, one of which is sand dominated channel deposits, and the other two are mudstone-sandstone, and mudstone dominated overbank deposits. The initial sedimentation
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Origin and evolution of the Paleo-Kuril arc inferred from detrital zircon U–Pb chronology in eastern Hokkaido, NE Asia Isl. Arc (IF 1.5) Pub Date : 2022-08-27 Futoshi Nanayama, Toru Yamasaki, Toshiya Kanamatsu, Hideki Iwano, Tohru Danhara, Takafumi Hirata
The Nemuro and Saroma Groups and Yusenkyo Formation occur in eastern Hokkaido and are considered to be forearc or intra-arc basin sediments of the Paleo-Kuril arc (PKA) deposited during the Late Cretaceous to middle Eocene. To further clarify the origin of the PKA, we examined the U–Pb ages of detrital zircons within these sandstones and acidic tuff beds; based on our results, we drew the following
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Middle Devonian ostracods from the Naidaijin Formation, Kurosegawa belt, Kyushu, Japan: Paleoecological and paleogeographical significance Isl. Arc (IF 1.5) Pub Date : 2022-08-27 Gengo Tanaka
This study reports five ostracod taxa from the Middle Devonian Naidaijin Formation, Kumamoto Prefecture, Kyushu, Japan comprising shelf-nearshore beyrichiid and bairdiocypridoid species, and two species of Bairdia. This is the first report of ostracod fossils from the Devonian strata in the Kurosegawa belt. Most analyzed fossils are the same species as those found in the Middle Devonian strata of Yunnan
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Age, petrogenesis, and tectonic implications of the late Permian magmatic rocks in the Middle Gobi volcanoplutonic Belt, Mongolia Isl. Arc (IF 1.5) Pub Date : 2022-08-21 Ariuntsetseg Ganbat, Tatsuki Tsujimori, Laicheng Miao, Inna Safonova, Daniel Pastor-Galán, Chimedtseren Anaad, Shogo Aoki, Kazumasa Aoki, Munkhnasan Chimedsuren
The Mongol–Okhotsk Belt, the youngest segment of Central Asian Orogenic Belt, was formed by the evolution and closure of the Mongol–Okhotsk Ocean. The oceanic closure formed two volcanoplutonic belts: Selenge Belt in the north and the Middle Gobi Belt in the south (in present day coordinates). However, the origin and tectonic evolution of the Mongol–Okhotsk Belt in general, and the origin and formation
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Stratigraphic reconstruction of the lower–middle Miocene Goto Group, Nagasaki Prefecture, Japan Isl. Arc (IF 1.5) Pub Date : 2022-08-12 Shoichi Kiyokawa, Masaru Yasunaga, Takanori Hasegawa, Ayako Yamamoto, Daisaku Kaneko, Yuta Ikebata, Noriko Hasebe, Yukiyasu Tsutsumi, Mami Takehara, Kenji Horie
The Goto Islands are located at the westernmost tip of the Japan archipelago, and preserve a lower–middle Miocene sedimentary sequence deposited during rifting of the continental margin and opening of the Sea of Japan. The stratigraphy of the Goto Group and new K–Ar, fission-track, and U–Pb age data were used to determine the initial conditions of rifting in southwest Japan. The thickness of the Goto
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2022 Island Arc Award Isl. Arc (IF 1.5) Pub Date : 2022-08-08
AWARDED PAPER Title: A visage of early Paleozoic Japan: Geotectonic and paleobiogeographical significance of Greater South China Author: Yukio Isozaki Reference: Island Arc (2019), 28, e12296