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Cisuralian calc-alkaline magmatism in the Herrera Unit of the Iberian Chain (Cantabrian Zone of the Iberian Massif, Spain): Age and geodynamic constraints from U-Pb LA-ICP-MS zircon analysis 西班牙伊比利亚地块坎塔布连带伊比利亚链Herrera单元的顺苏拉期钙碱性岩浆作用:U-Pb LA-ICP-MS锆石分析的年龄和地球动力学约束
3区 地球科学
Journal of the Geological Society Pub Date : 2023-11-03 DOI: 10.1144/jgs2022-102
Urbez Majarena, José Julián Estéban, Carlos Galé, Andrés Gil-Imaz, Marceliano Lago
{"title":"Cisuralian calc-alkaline magmatism in the Herrera Unit of the Iberian Chain (Cantabrian Zone of the Iberian Massif, Spain): Age and geodynamic constraints from U-Pb LA-ICP-MS zircon analysis","authors":"Urbez Majarena, José Julián Estéban, Carlos Galé, Andrés Gil-Imaz, Marceliano Lago","doi":"10.1144/jgs2022-102","DOIUrl":"https://doi.org/10.1144/jgs2022-102","url":null,"abstract":"The Herrera Unit of the Iberian Chain (Cantabrian Zone, Iberian Massif) exhibits hundreds of outcrops of calc-alkaline igneous rocks that have been classically attributed to the Upper Carboniferous and the Lower Permian, although only two absolute radiometric ages have been reported. This work, with six new zircon laser ablation inductively coupled plasma mass spectrometry ages obtained from some of the most representative outcrops, provides the most complete age repository for the calc-alkaline magmatism of the prolongation of the Cantabrian Zone within the Iberian Chain. The obtained ages range between 294 and 288 Ma (Cisuralian Epoch) and show a well-defined peak at 290 Ma, which can be attributed to a main magmatic activity stage. This result allows us to correlate and integrate this magmatism within the widespread SW European calc-alkaline magmatism province developed under strike-slip tectonics. Therefore, the Iberian Chain magmatism and its age can be considered as a good temporal marker for the upper limit of the compressive tectonics associated with the Variscan Orogeny and the onset of the extensional tectonics linked to Permo-Triassic rifting. Supplementary material: Analytical settings (1) and analytical data from: the standard zircons (2) and the zircons from the samples of this work (3) are available at https://doi.org/10.6084/m9.figshare.c.6843778","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"182 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135775741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Cambrian ages for metavolcanic rocks in the Lower Kӧli Nappes, Swedish Caledonides: Implications for the status of the Virisen arc terrane 瑞典加里东尼德下部Kӧli推覆体中变质火山岩的寒武纪时代:对Virisen弧地体状态的启示
3区 地球科学
Journal of the Geological Society Pub Date : 2023-11-03 DOI: 10.1144/jgs2022-130
Isabel S. M. Carter, Simon J. Cuthbert, Katarzyna Walczak, Grzegorz Ziemniak, Ellen Kooijman, Jarosław Majka
{"title":"Cambrian ages for metavolcanic rocks in the Lower Kӧli Nappes, Swedish Caledonides: Implications for the status of the Virisen arc terrane","authors":"Isabel S. M. Carter, Simon J. Cuthbert, Katarzyna Walczak, Grzegorz Ziemniak, Ellen Kooijman, Jarosław Majka","doi":"10.1144/jgs2022-130","DOIUrl":"https://doi.org/10.1144/jgs2022-130","url":null,"abstract":"The Köli Nappe Complex (KNC) of the Scandinavian Caledonide orogen originated as oceanic terranes within the Iapetus Ocean. These terranes have characteristics of magmatic arcs and associated forearc or back-arc basins and underwent several periods of rifting and magmatism prior to their accretion to the Baltican margin. We present new U–Pb zircon ages from the Lower Köli Ankarede Volcanite Formation in Västerbotten, Sweden. U–Pb ages of magmatic zircon grains from metamorphosed dacitic to andesitic rocks show ages of 512 ± 3.5, 497 ± 2, 491 ± 1 and 488 ± 4 Ma. The three younger ages fit with previous ages for Lower Köli volcanic rocks, but the 512 Ma age is older than any previous age for this unit. These dates constrain the age of magmatism in an ensimatic arc system within Iapetus. We compare this evolution with published information from the other Köli nappes. Magmatic ages within the KNC overlap with ages for an early episode of ultrahigh-pressure (UHP) metamorphism within the underlying Seve Nappe Complex (SNC), supporting the hypothesis that attributes UHP metamorphism within the SNC to subduction beneath the island arc now preserved within the Lower Köli Nappes. Supplementary material: Photographs of sampled exposures (S1), BSE images of selected zircons (S2), charts of zircon trace elements (S3) and analyses of zircon (S4, S5) are available at https://doi.org/10.6084/m9.figshare.c.6843787 Thematic collection: This article is part of the Caledonian Wilson cycle collection available at: https://www.lyellcollection.org/topic/collections/the-caledonian-wilson-cycle","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"182 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135775742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Tectono-Stratigraphic Evolution of Salt-Influenced Normal Fault Systems: An Example From The Coffee-Soil Fault, Danish North Sea 盐影响的正断层系统的构造-地层演化:以丹麦北海咖啡-土壤断层为例
3区 地球科学
Journal of the Geological Society Pub Date : 2023-11-03 DOI: 10.1144/jgs2023-016
Oliver B. Duffy, Rob L. Gawthorpe, Matthew Docherty
{"title":"Tectono-Stratigraphic Evolution of Salt-Influenced Normal Fault Systems: An Example From The Coffee-Soil Fault, Danish North Sea","authors":"Oliver B. Duffy, Rob L. Gawthorpe, Matthew Docherty","doi":"10.1144/jgs2023-016","DOIUrl":"https://doi.org/10.1144/jgs2023-016","url":null,"abstract":"We explore how the relationships between fault activity, salt movement and sediment loading affect the stratal geometry of the hanging wall throughout the evolution of a salt-influenced normal fault system. We examine a c. 65 km long portion of the Coffee-Soil Fault System in the Danish North Sea, the hanging wall of which has been partially influenced by a pre-rift unit of mobile salt. To constrain the tectono-stratigraphic evolution of this fault system, we combine structural observations with seismic stratigraphic analysis of the hanging wall growth strata. We find that the hanging wall of the Coffee-Soil Fault System shows major depocentre shifts through time, along with marked variability in the along- and across-strike stratal geometries. We explain how the development of these characteristics is influenced by: (1) the segmentation and linkage history of the fault system; (2) the evolution of the salt-cored cover monoclines above blind basement fault segments; and (3) changes in the location and rate of accommodation generated by the load-driven withdrawal of salt up the dip-slope of the hanging wall and by fault-related subsidence. Our findings have implications for structural and stratigraphic studies in salt-influenced rift basins, as well as for understanding the potential distribution of geo-storage and hydrocarbon reservoirs in such settings.","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"181 S473","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135775743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Multiple carbon isotope excursions during the Carnian (Late Triassic) pluvial event: Implications for global and regional perturbation 卡尼期(晚三叠世)洪积事件期间的多重碳同位素偏移:对全球和区域扰动的影响
3区 地球科学
Journal of the Geological Society Pub Date : 2023-11-03 DOI: 10.1144/jgs2022-168
Puyang Ke, Xiugen Fu, Qinghua Peng, Hengye Wei, Yuhong Zeng, Qian Zhang, Jinxian Deng
{"title":"Multiple carbon isotope excursions during the Carnian (Late Triassic) pluvial event: Implications for global and regional perturbation","authors":"Puyang Ke, Xiugen Fu, Qinghua Peng, Hengye Wei, Yuhong Zeng, Qian Zhang, Jinxian Deng","doi":"10.1144/jgs2022-168","DOIUrl":"https://doi.org/10.1144/jgs2022-168","url":null,"abstract":"The Late Triassic Carnian pluvial event (CPE) was an interval marked by global climatic and environmental changes that occurred simultaneously with enhancement of the hydrological cycle. This event is characterized by multiple negative carbon isotope excursions (NCIEs). However, the driving mechanism behind these multiple NCIEs remains elusive because each of the NCIEs had different magnitudes in different geological settings. In this study, we present a high-resolution record of carbonate carbon isotope ( <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mi>δ</mml:mi> </mml:math> 13 C carb ) and major and trace element data from Well QZ-8 in the Qiangtang Basin, eastern Tethys. The carbon isotope profile from this well displays a similar trend to those for contemporaneous strata in the NW Tethys and South China. This trend is characterized by a distinct negative excursion during the CPE, supporting a global event. Interestingly, our results reveal five NCIEs for the first time in the marine sedimentary succession. Furthermore, each of these NCIEs corresponds well to changes in Ti/Al, Sr/Al and Sr/Ba, suggesting a regional effect of the hydrological cycle on carbon isotope excursions. This study emphasizes that each of the NCIEs was influenced by regional hydrological cycles although the long carbon isotope excursion during the CPE was driven by the global carbon cycle. Supplementary material: Tables showing major element, isotope and trace element data and element ratios, and a supplementary figure are available at https://doi.org/10.6084/m9.figshare.c.6805266","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"186 1‐6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135775905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The Charnwood Terrane revisited: an integrated petrogenetic and petrophysical model for crustal structure in S Britain 重新审视查恩伍德地体:英国南部地壳结构的岩石成因和岩石物理综合模型
3区 地球科学
Journal of the Geological Society Pub Date : 2023-11-03 DOI: 10.1144/jgs2023-001
T.C. Pharaoh, D. Beamish, J.D.O. Williams, J.N. Carney, P.R.W. Wilby
{"title":"The Charnwood Terrane revisited: an integrated petrogenetic and petrophysical model for crustal structure in S Britain","authors":"T.C. Pharaoh, D. Beamish, J.D.O. Williams, J.N. Carney, P.R.W. Wilby","doi":"10.1144/jgs2023-001","DOIUrl":"https://doi.org/10.1144/jgs2023-001","url":null,"abstract":"We based an integrated petrological and petrophysical model for the Ediacaran crust of southern Britain on a review of the c. 570–550 Ma Charnian volcano-sedimentary complex. The latter was emplaced in a magmatic rift wedge within the juvenile continental crust of the c. 720–600 Ma Marches Terrane, a subduction magmatic domain formed at the margin of the Gondwana palaeocontinent. The Charnian magmatic arc is characterized by primitive island arc tholeiite to more evolved calc-alkaline compositions. The inversion of aeromagnetic potential field data and petrophysical modelling reveals details of the internal structure of the Charnian Domain, including a median rift, superimposed annular structures and partitioning lineaments. The modelling suggests that the arc foundation could incorporate magnetite-rich cumulates, which may explain the anomalous geophysical properties, including crustal thickness, rigidity and buoyancy. There is no evidence for significant tectonic displacement between the Charnian Domain and its Marches Terrane host. Instead, the domain likely occupies a wedge-shaped arc/marginal rift basin complex, propagated from a neighbouring ocean into the Gondwana margin. Contemporaneous volcanic rift successions in the Welsh Borderland and Wales of the 570–550 Ma Charnian magmatic phase developed in coeval ensialic rifts within less strongly extended Marches Terrane lithosphere. A comparable diversity of subduction-related magmatism is found in the Neogene–recent Hikurangi destructive margin of New Zealand, providing a plausible analogue for Charnian magmatism. Supplementary material: Supplementary Publication 1 (borehole geophysical log correlation; petrophysical data table; unannotated geophysical maps and sections) and Supplementary Publication 2 (geochemistry analytical conditions and data table) are available at https://doi.org/10.6084/m9.figshare.c.6805248","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"185 S500","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135775906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Old detrital AFT ages from E. Greenland do not require plateau erosion 格陵兰岛东部的旧碎屑AFT年龄不需要高原侵蚀
3区 地球科学
Journal of the Geological Society Pub Date : 2023-11-01 DOI: 10.1144/jgs2023-103
Matthew Fox, Vivi Pedersen
{"title":"Old detrital AFT ages from E. Greenland do not require plateau erosion","authors":"Matthew Fox, Vivi Pedersen","doi":"10.1144/jgs2023-103","DOIUrl":"https://doi.org/10.1144/jgs2023-103","url":null,"abstract":"Accurate estimates of past topography are required to reliably reconstruct past ice sheets to infer paleoclimate. For this reason, understanding erosion rates across East Greenland is crucial to constrain landscape evolution driven by tectonics and climate-dependent erosion rates. Here we analyse published apatite fission track (AFT) data to constrain the spatial pattern of AFT bedrock ages across the landscape. We compare these bedrock ages with published detrital distribution to highlight ambiguity in the pattern of erosion. In contrast to earlier work, we regress a simple model of exhumation pace through the bedrock ages such that age can vary both as a function of elevation and position. The resulting iso-age surfaces enable us to determine potential source areas for detrital AFT ages distributions. We find that old ages observed in detrital distributions are just as likely to be sourced from low-elevation locations that are far from the coast, as high elevation locations close to the coast. Additional data from lower temperature systems are thus required to make firm conclusions on landscape evolution in the region and distinguish between the two landscape-forming scenarios.","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"56 1-2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135222008","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Organic matter enrichment and paleo-sedimentary environment reconstruction of lacustrine shale in the second member of the Middle Jurassic Qiketai Formation in Shengbei Sub-sag, Turpan-Hami Basin, northwest China 吐哈盆地胜北次凹陷中侏罗统七克台组二段湖相页岩有机质富集与古沉积环境重建
3区 地球科学
Journal of the Geological Society Pub Date : 2023-10-31 DOI: 10.1144/jgs2023-093
Boran Wang, Zhilong Huang, Tianjun Li, Guobin Fu, Jingyi Yan
{"title":"Organic matter enrichment and paleo-sedimentary environment reconstruction of lacustrine shale in the second member of the Middle Jurassic Qiketai Formation in Shengbei Sub-sag, Turpan-Hami Basin, northwest China","authors":"Boran Wang, Zhilong Huang, Tianjun Li, Guobin Fu, Jingyi Yan","doi":"10.1144/jgs2023-093","DOIUrl":"https://doi.org/10.1144/jgs2023-093","url":null,"abstract":"Lacustrine organic-rich shales in the second member of the Jurassic Qiketai Formation (J 2 q 2 ) in the Shengbei Sub-sag, Turpan-Hami basin, northwest China exhibit strong heterogeneity due to frequent alternations of sedimentary environments. The distinct shale environments present in both upper and lower units of J 2 q 2 provide an ideal example for studying the enrichment mechanism of organic matter (OM) under a complex sedimentary background. In this study, petrological, mineralogical, major/trace element, and isotopic analyses were used to reconstruct the paleo-environment and reveal the mechanisms of OM enrichment. The results indicate that the J 2 q 2 shale was deposited in a lacustrine mixed carbonate-siliciclastic environment and the paleo-environment indicators suggesting an oxic-dysoxic, mildly brackish water condition. Based on a comprehensive comparison of both members of J 2 q 2 , an OM enrichment model was established and the main controlling factor of the formation of the organic-rich shale is elucidated. Under the background of a warm-humid climate, the lower unit of J 2 q 2 was deposited in a deeper and more restricted water body with stronger chemical weathering, resulting in limited terrestrial input compared to that of the upper unit. The inorganic geochemical analysis indicates a higher primary productivity in the lower unit of J 2 q 2 with local fluctuations. High primary productivity and favorable preservation conditions domain the OM enrichment in the study area. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6901480","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"326 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135863189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Metamorphosed mélange in eastern Himalayan syntaxis: constraint for the India-Asia collision in Eocene 东喜马拉雅构造合带的变质岩:始新世印度-亚洲碰撞的约束
3区 地球科学
Journal of the Geological Society Pub Date : 2023-10-27 DOI: 10.1144/jgs2023-067
Zhen Wei, Xianghui Li, Minjia Sun, Xiaolong Fan, Jingyu Wang, Juanjuan Zhou, Shoucai Wei
{"title":"Metamorphosed mélange in eastern Himalayan syntaxis: constraint for the India-Asia collision in Eocene","authors":"Zhen Wei, Xianghui Li, Minjia Sun, Xiaolong Fan, Jingyu Wang, Juanjuan Zhou, Shoucai Wei","doi":"10.1144/jgs2023-067","DOIUrl":"https://doi.org/10.1144/jgs2023-067","url":null,"abstract":"Tectonic mélanges are crucial for deciphering collision processes in orogenic belts. This study investigates the nature of metamorphosed mélange in the Milin area of the eastern Himalayan syntaxis to shed light on the India-Asia collision in the region. The mélange exhibits a “block-in-matrix” fabric in the lower and upper parts and a “lenticular-thrust-slices” fabric in the middle. Quartzite blocks in the lower part are proposed to be the Silurian or younger quartz arenites with a Tethyan affinity. Metacherts and amphibolites in the middle and upper parts may have originated from hydrothermal or terrestrial cherts and Nb-enriched basalts in the Asian forearc or syncollisional basin at ∼48-45 Ma. The diverse blocks/slices of the mélange, sourced from both the subducting and overriding plates, are suggested to be formed during Indian plate subduction. The protoliths of the amphibolite-metachert slice (∼45 Ma) in the mélange are distinctly different from the contemporary shallow sea (post-collisional) deposits but similar to the deep-water (initial collisional or pre-collisional) sediments in other parts of the suture zone. This implies that the amphibolite-metachert slice may represent the product of the initial India-Asia collision or even pre-collision and that (hard) collision likely lagged by ∼10-Myr in the eastern Himalaya syntaxis. Thematic collection: This article is part of the Ophiolites, melanges and blueschists collection available at: https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists Supplementary material: https://doi.org/10.6084/m9.figshare.c.6896942","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136261722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Chemostratigraphy of the extrusive sequence of a Late Cretaceous Neotethyan ophiolite in Southern Iran and its significance for the mode and tempo of subduction initiation magmatism and melt evolution in forearc tectonic settings 伊朗南部晚白垩世新特提斯期蛇绿岩挤出层序的化学地层学及其对弧前构造背景下俯冲起始岩浆活动和熔体演化模式、速度的意义
3区 地球科学
Journal of the Geological Society Pub Date : 2023-10-26 DOI: 10.1144/jgs2023-080
Hadi Shafaii Moghadam, Yildirim Dilek, Harald Furnes, Osamu Ishizuka, Massimo Chiaradia, Qiu-li Li, Orhan Karsli, Federico Lucci, Ali Asadi
{"title":"Chemostratigraphy of the extrusive sequence of a Late Cretaceous Neotethyan ophiolite in Southern Iran and its significance for the mode and tempo of subduction initiation magmatism and melt evolution in forearc tectonic settings","authors":"Hadi Shafaii Moghadam, Yildirim Dilek, Harald Furnes, Osamu Ishizuka, Massimo Chiaradia, Qiu-li Li, Orhan Karsli, Federico Lucci, Ali Asadi","doi":"10.1144/jgs2023-080","DOIUrl":"https://doi.org/10.1144/jgs2023-080","url":null,"abstract":"Chemostratigraphy of lavas in extrusive sequences of modern and ancient forearc environments provides significant information on oceanic crust formation through progressive stages of melt evolution from subduction initiation magmatism (SIM) to arc infancy, and arc maturation-related magmatism. We present here new trace element and radiogenic Sr–Nd–Pb isotopic data from a Late Cretaceous ophiolite in the Outer Zagros Belt of southern Iran and discuss its magmatic development through SIM in a Neotethyan forearc setting. Initial volcanism produced the stratigraphically oldest boninitic (BON) lavas in the Haji-Abad ophiolite whose trace element ratios as well as Pb isotopic signatures indicate a refractory mantle source, which was contaminated by subducting slab-derived fluids. The BON lavas change structurally upwards into island-arc tholeiitic (IAT) lavas and their fractionated felsic derivatives that display isotopic evidence for the contribution of sediment-derived melts in their magmatic source(s). This melt evolution pattern of the Haji-Abad ophiolite marks a major difference from the progressive melt evolution trends reported from the Izu–Bonin–Mariana (IBM) forearc lava sequence, which starts at the bottom with forearc basalts (FAB) phasing up-section into BON and IAT affinity lavas. IAT lavas in the IBM are in turn overlain by calc-alkaline (CAL) lavas. Our geochemical modelling points to a probable existence of a less depleted, pre-subduction mantle whose partial melting probably generated primary magmas before the eruption of boninitic lavas, although the record of such magmas is missing in the Haji-Abad ophiolite. Our comparison of the chemostratigraphy of the Outer Zagros ophiolites with the documented record of subduction initiation generated volcanic rocks in the other Neotethyan ophiolites in the region and the IBM forearc setting strongly suggests that there is no single rule or template for SIM. Supplementary material: Details of analytical procedures and supplementary figures and tables are available at https://doi.org/10.6084/m9.figshare.c.6837597 Thematic collection: This article is part of the Ophiolites, melanges and blueschists collection available at: https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists","PeriodicalId":17320,"journal":{"name":"Journal of the Geological Society","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136376537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The evolution of the Mesozoic lithosphere of northwestern Neotethys: A petrogenetic and geodynamic perspective 新特提斯西北部中生代岩石圈演化:岩石成因和地球动力学的视角
3区 地球科学
Journal of the Geological Society Pub Date : 2023-10-24 DOI: 10.1144/jgs2023-132
Damir Slovenec, Branimir Šegvić
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