Island Arc最新文献

{"title":"Granite rock towers shaped by mesh-like joint sets, which formed in the shallower portion of a granite body during cooling at depth","authors":"Masahiro Chigira,&nbsp;Hironori Kato","doi":"10.1111/iar.12484","DOIUrl":"10.1111/iar.12484","url":null,"abstract":"<p>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 Hiroshima, was investigated using an unmanned air vehicle. The rock towers were shaped by high-angle mesh-like joints, which were likely made during the cooling of the granite and are dominated by three joint sets. All the joint sets have sharp planar surfaces, which suggests that they are brittle fractures. One joint set is cut by the other two joint sets, frequently accompanies aplite and quartz veins and is developed in the whole exposed granite; this set likely formed first during cooling and then was penetrated by aplite from depth. The other two joint sets are high-angle conjugate joint sets, are limited to the shallower portion of the granite pluton and do not extend deeper, which strongly suggests that they formed in a rapidly cooled shallower portion of the pluton, probably near its roof. These three joint sets form rock columns with parallelogram cross-sections, in which incipient corestones were made. Subsurface weathering along the joints and subsequent exhumation of the weathering products formed the present rock towers and corestones only in the shallower portion of the granite.</p>","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":"32 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/iar.12484","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47431194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrogenesis of mafic rocks from northwest Iran (Piranshahr) and comparison with northeast Iraq ophiolites: Implications for slab window magmatism in an evolving Neotethys arc","authors":"Maryam Yazdani,&nbsp;Mohssen Moazzen,&nbsp;Roland Oberhänsli","doi":"10.1111/iar.12481","DOIUrl":"10.1111/iar.12481","url":null,"abstract":"<p>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 be identified among the ophiolitic basalts in northwest Iran and northeast Iraq. The first one is represented by Late Cretaceous calc-alkaline basalts, displaying typical active continental margin signatures and thought to have been derived from the melting of enriched mantle sources modified by continental crust and subduction fluids. The second group is characterized by Eocene–Oligocene tholeiitic basalts, displaying signatures intermediate between mid-ocean ridge basalt (MORB) and oceanic island basalt (OIB) and back-arc basin (BAB) like magmas and suggested to have been derived from the melting of mixed asthenospheric-lithospheric mantle sources in a slab window. We propose that the subduction signature is acquired by interaction of the mantle advected through the slab window in the upper part of the subducting plate.</p>","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":"32 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49649882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"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","authors":"Xiaodong Zhou,&nbsp;Tongchun Nie,&nbsp;Zhiding Han,&nbsp;Xilin Zhao","doi":"10.1111/iar.12483","DOIUrl":"10.1111/iar.12483","url":null,"abstract":"<p>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 and diorite. The results of geochronology indicate that the granodiorite and diorite emplaced at 450 ± 3.9 Ma and 443 ± 4.0 Ma. Their emplacement time were well corresponding to the subduction stage of the Yunkai orogeny in the southwestern part of Cathaysia block during the Early Paleozoic (460–440 Ma). The Puyang adakite-like granodiorite shows enrichments in Sr, but depletions in Y and Yb contents, high in Na₂O, K₂O and Al₂O₃, with <i>ε</i>_Hf(<i>t</i>) values range from −10.5 to −7.4 (mean of −9.0) and two-stage Hf model ages range from 1.91 to 2.10 Ga. These characteristics indicate that the magmas were generated by partial melting of subducted oceanic crust mixed with melts from the above wedgy mantle peridotite. The Puyang high-Mg diorite shows enrichments in Sr and Ba, depletions in Rb, Y and Yb contents, and strongly high in MgO and Al₂O₃ contents, with <i>ε</i>_Hf(<i>t</i>) values of −2.9 to 0 (mean of −1.4) and two-stage Hf model ages of 1.43 to 1.61 Ga. These indicate that the magmas were mainly generated by partial melting of the wedgy mantle peridotite, mixed by adakitic melts from subducted oceanic slab. Comprehensive analysis shows that Puyang adakite-like granodiorite and high-Mg diorite were formed in fore-arc setting, where the mantle and crustal magmas mixed during the oceanic subduction initiation period. By extension, this study offered important evidences to support the point that the Caledonian orogeny in South China was related to oceanic subduction which initiated prior to ~450 Ma.</p>","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":"32 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41903621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"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","authors":"Zhu Qingbo,&nbsp;Wang Cunzhi,&nbsp;Zhao Xilin,&nbsp;Jin Guodong,&nbsp;Gao Tianshan","doi":"10.1111/iar.12480","DOIUrl":"10.1111/iar.12480","url":null,"abstract":"<p>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 belt lack comprehensive understanding. Based on the zircon U–Pb geochronology, Hf isotope and trace element analyses of the deformed matrix in the NE Jiangxi ophiolitic mélange belt, we report the ages of meta-rhyolite and tuffaceous phyllite to be 800–760 Ma, and the maximum depositional age of the clastic matrix is ~760 Ma. The youngest deformed matrix ages of 800–760 Ma constrain the tectonic emplacement age of the NE Jiangxi ophiolitic mélange belt to the late Qingbaikou period after 800–760 Ma and before the deposition of the Xiuning Formation (765–732 Ma). Zircon ages, trace element and Hf isotope compositions indicate that the 800–760 Ma matrix was formed in a back-arc basin environment with obvious addition of 1000–800 Ma arc materials and recycled Paleoproterozoic crustal materials. The detrital material source areas were the 800–760 Ma arc and earlier accretionary wedge as juvenile crust. The multi-stage arc magmatism, metamorphism and deformation in the NE Jiangxi ophiolitic mélange belt suggest that multi-stage subduction of the Paleo-South China Ocean and Neoproterozoic accretionary orogeny occurred during 1–0.76 Ga at the southeast margin of the Yangtze Block. Combined with the regional geological data, the Neoproterozoic back-arc basin or the foreland basin around the Yangtze Block closed after ~760 Ma. The collision and amalgamation of the Yangtze and Cathaysia blocks resulted in the final closure of the Paleo-South China Ocean, which have occurred in the early Paleozoic.</p>","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":"32 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48565692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction to Middle Holocene relative sea-level changes and vertical tectonic crustal movements on Shikoku Island near the Nankai Trough, Japan","authors":"","doi":"10.1111/iar.12477","DOIUrl":"10.1111/iar.12477","url":null,"abstract":"<p> <span>Yamaguchi, T.</span>, <span>Nanayama, F.</span>, <span>Nakanishi, T.</span>, <span>Tsuji, T.</span>, <span>Ikeda, M.</span>, <span>Kondo, Y.</span>, <span>Miwa, M.</span>, &amp; <span>Hamada, Y.</span> (<span>2022</span>). <span>Middle Holocene relative sea-level changes and vertical tectonic crustal movements on Shikoku Island near the Nankai Trough, Japan</span>. <i>Island Arc</i>, <span>31</span>(<span>1</span>), e12452. https://doi.org/10.1111/iar.12452</p><p>On page 9, third paragraph, the Dryad Digital Repository link (https://datadryad.org/stash/share/Caof8eH1lrqg2vUUvuH20N71TqbLAOHBt4g5ydr8W2g) is outdated and inaccessible. The link has been updated and can be accessed on https://datadryad.org/stash/dataset/doi:10.5061%2Fdryad.pc866t1kk.</p><p>We apologize for this error.</p>","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":"32 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/iar.12477","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44224653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"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","authors":"Diezeneino Meyase,&nbsp;Vikoleno Rino,&nbsp;Santosh Kumar,&nbsp;Rokozono Nagi","doi":"10.1111/iar.12479","DOIUrl":"10.1111/iar.12479","url":null,"abstract":"<p>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 conditions of the LPC granitoid magmas. The studied granitoids are well-exposed in the Dibang and Lohit valleys, and their MS values indicate a bi-modal patterns corresponding to ilmenite (reduced) series (71%) and magnetite (oxidized) series (29%) granites. The variation of MS in the LPC granitoids is related to the alteration of ferromagnetic minerals, and later tectonic and deformational processes that acted upon them. The amphiboles from the LPC granitoids are calcic (Ca_B &gt;1.5, Si = 6.30–7.06 apfu) and exhibit tschermak substitutions typical to their evolution in a calc alkaline, metaluminous (I-type) felsic magmas. Al-in-hornblende rims estimate the emplacement of quartz diorite and granodiorite magmas at shallow (~5 km) and mid (~16 km) crustal depths. Geothermometric results point to a regime of magmatic crystallization (940–837°C for quartz diorite; 882–829°C for granodiorite) sufficiently above the solidus of respective melts. Biotites from LPC granitoids are primary to re-equilibrated, and transitional between magnesio- and ferri-biotites. Quartz diorite and granodiorite biotites evolved under oxidizing magmas (log ƒO₂⁻¹⁴ to log ƒO₂⁻¹³) in a temperature range of ~750–950°C, typical to their formation in a calc alkaline magma of subduction zone environment. However, the biotites from leucogranite appear to have evolved under a mildly reducing magma environment, most likely attained in a collisional setting. The obtained results suggest that the oxidized nature of calc alkaline, subduction-related magmatic arc rocks of the LPC is largely modified and reduced by post-magmatic, and later tectonothermal and deformational events that operated during Himalayan and Trans-Himalayan orogenesis.</p>","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":"32 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43424727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrogeochemistry and geothermometry of the Ilgın geothermal field, Central Turkey","authors":"Ali Ferat Bayram","doi":"10.1111/iar.12478","DOIUrl":"https://doi.org/10.1111/iar.12478","url":null,"abstract":"<p>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 of the thermal waters. The chemical properties of the cold and hot waters collected from the field were determined and the classification and usage possibilities of the waters were investigated. The thermal well water samples have the same Cl, B and Li concentrations in rainy and dry seasons, but those of the other samples are variable in rainy and dry seasons. This suggests the surface water mixtures were constant in hot water wells or that the precipitation times were long. In the Li-Rb-Cs diagram, the Li/Cs ratios of hot waters are 6.53–8.61 in the rainy period and 6.28–8.47 in the dry period, indicating that they are derived from acidic rocks. According to their isotopic composition, it can be said that the waters are of meteoric origin. According to the Langelier, the Ryznar and the Puckorius Saturation Indexes, the waters can precipitate carbonate. The waters interacted with gypsum and anhydrite zones based on the Halite Saturation Index, while the waters are associated with dolomite-rich rocks in terms of the Dolomite Saturation Index. Silica and cation geothermometers except Na-K applicated to the Ilgın geothermal waters yielded similar reservoir temperature estimates (e.g., 13–76°C for rainy period, 10–80°C for dry period). However, reservoir temperature from the other estimates (Na-K geothermometers, enthalpy-chloride diagram and enthalpy-silica mixture model) are higher than 103°C. Taken as whole, the temperature estimates exhibit little agreement between the different geothermometry calculations suggesting that the Ilgın geothermal waters represent immature waters, and water-rock equilibrium in the geothermal reservoir was not fully attained.</p>","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":"32 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50116183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"HYDROGEOCHEMISTRY AND GEOTHERMOMETRY OF THE ILGIN GEOTHERMAL FIELD, CENTRAL TURKEY","authors":"A. F. Bayram","doi":"10.1111/iar.12478","DOIUrl":"https://doi.org/10.1111/iar.12478","url":null,"abstract":"","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42741315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recent advances in signaling and activation mechanism in microbial rhodopsins: Report for the session 6 at the 19^th International Conference on Retinal Proteins.","authors":"Kazumi Shimono, Norbert A Dencher","doi":"10.2142/biophysico.bppb-v20.s009","DOIUrl":"10.2142/biophysico.bppb-v20.s009","url":null,"abstract":"","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":"19 1","pages":"e201009"},"PeriodicalIF":0.0,"publicationDate":"2023-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10865883/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85327552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fossil diatom assemblage changes due to paleoenvironment change, tsunami, and typhoon in southern Japan","authors":"Ara Cho,&nbsp;Kaoru Kashima,&nbsp;Hannah Baranes,&nbsp;Caroline Ladlow,&nbsp;Kota Katsuki,&nbsp;Jonathan D. Woodruff","doi":"10.1111/iar.12476","DOIUrl":"10.1111/iar.12476","url":null,"abstract":"<p>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 in southern Japan where flood deposits have been linked to historical typhoon and tsunami events (Lakes Kawahara and Ryuo). The sediment cores extend from B.C.E. 500 to approximately C.E. 1000 and the downcore variation in diatom assemblages indicates a series of transitions from saline to fresher conditions in both Lake Kawahara and Lake Ryuo between approximately C.E. 500 and 1700. We observe an obvious deviation in diatom assemblages in event deposits previously identified to be either of tsunami or typhoon in origin. For the most prominent event deposit preserved in Lake Ryuo by the Hoei tsunami of C.E. 1707, the deposition of marine diatoms serves as evidence of marine flooding, while the subsequent deposition of soil and freshwater diatoms indicates the mobilization of terrigenous sediment during returning seaward flows. In contrast, the most prominent event deposit in Lake Kawahara is associated with freshwater flooding by the Kamikaze typhoon of C.E. 1281 and contains very low diatom abundances and a peak of freshwater taxa, followed by a peak in diatom counts potentially due to greater biological activity induced by a resultant influx of nutrients and re-oxygenation during the event.</p>","PeriodicalId":14791,"journal":{"name":"Island Arc","volume":"32 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41527807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}