The mechanisms of uplift and deformation of the Tibetan Plateau are highly concerned. Understanding the crustal deformation mechanisms beneath southeast Tibet is important as it is located at the major path of Tibet's growth or expansion. Recent studies are controversial on whether large‐scale crustal flow is dominant or not in this area. We applied Pms arrival time technique based on receiver function to events from 10 years of observation and obtained the crustal anisotropy parameters. The results show that both the large‐scale faults and local crustal flow play major roles in crustal deformation in interested areas, while the large‐scale crustal flow is not very well preferred. Furthermore, the crustal anisotropy in southeast of the study area is characterized by complex anisotropies, which may be potentially related to the converging of two mantle flows from various origins.
{"title":"Crustal anisotropy beneath southeast Tibet revealed by Pms arrival times","authors":"Peixi Huang, Yuan Gao, Jing Wu","doi":"10.1111/ter.12714","DOIUrl":"https://doi.org/10.1111/ter.12714","url":null,"abstract":"The mechanisms of uplift and deformation of the Tibetan Plateau are highly concerned. Understanding the crustal deformation mechanisms beneath southeast Tibet is important as it is located at the major path of Tibet's growth or expansion. Recent studies are controversial on whether large‐scale crustal flow is dominant or not in this area. We applied <jats:italic>Pms</jats:italic> arrival time technique based on receiver function to events from 10 years of observation and obtained the crustal anisotropy parameters. The results show that both the large‐scale faults and local crustal flow play major roles in crustal deformation in interested areas, while the large‐scale crustal flow is not very well preferred. Furthermore, the crustal anisotropy in southeast of the study area is characterized by complex anisotropies, which may be potentially related to the converging of two mantle flows from various origins.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"90 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576331","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}
Ios (an island in the Cycladic archipelago, Greece) was the first recognized Aegean metamorphic core complex. There is a paradoxical absence of an age jump in low‐temperature geochronology transects across the Ios Detachment Fault. This paper explains why this is so, by modelling the conductive response to detachment faulting. We demonstrate that transects across detachment faults consistently record age jumps only at shallow palaeodepths. Conductive relaxation of the perturbed geotherm keeps pace with fault movement, so the hangingwall heats just as fast as the footwall cools. Key variables are the fractional depth to the partial resetting zone, d [0.0.1], and the magnitude and rate of slip on the detachment. At shallow palaeodepths (d < 0.3, 10–50 km slip), significant age jumps occur across the actual fault contact. At deeper levels of exposure, this is no longer the case, and the effects of a ‘stewing zone’ readily become evident.
伊奥斯（希腊基克拉泽斯群岛的一个岛屿）是第一个被确认的爱琴海变质岩核心复合体。在穿越伊奥斯断裂的低温地质年代横断面上，没有出现年龄跃变的现象，这是一个矛盾的现象。本文通过对剥离断层的传导反应建模，解释了为什么会出现这种情况。我们证明，穿越剥离断层的横断面只有在浅古深度才会持续记录年龄跃变。扰动地温的传导松弛与断层运动保持同步，因此悬壁加热的速度与底壁冷却的速度一样快。关键变量是部分重置带的部分深度 d [0.0.1]，以及脱离层的滑动幅度和速度。在较浅的古深度（d < 0.3，10-50 千米滑动），实际断层接触处会出现明显的年龄跃变。在较深的出露层，情况就不再是这样了，"焖烧区 "的影响很容易显现出来。
{"title":"Low‐temperature thermochronology and the timing of motion on detachment faults","authors":"Gordon Lister, Marnie Forster","doi":"10.1111/ter.12713","DOIUrl":"https://doi.org/10.1111/ter.12713","url":null,"abstract":"Ios (an island in the Cycladic archipelago, Greece) was the first recognized Aegean metamorphic core complex. There is a paradoxical absence of an age jump in low‐temperature geochronology transects across the Ios Detachment Fault. This paper explains why this is so, by modelling the conductive response to detachment faulting. We demonstrate that transects across detachment faults consistently record age jumps only at shallow palaeodepths. Conductive relaxation of the perturbed geotherm keeps pace with fault movement, so the hangingwall heats just as fast as the footwall cools. Key variables are the fractional depth to the partial resetting zone, <jats:italic>d</jats:italic> [0.0.1], and the magnitude and rate of slip on the detachment. At shallow palaeodepths (<jats:italic>d</jats:italic> < 0.3, 10–50 km slip), significant age jumps occur across the actual fault contact. At deeper levels of exposure, this is no longer the case, and the effects of a ‘stewing zone’ readily become evident.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"89 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576529","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}
Jarek Trela, Jared T. Freiburg, Esteban Gazel, Laurence Nuelle, Anton H. Maria, David H. Malone, John M. Molinarolo
New petrological, geochemical, and P–T modelling results from igneous samples clarify how carbonatite‐lamprophyre magmatism, fluorite and rare earth element (REE) enrichment are petrogenetically related in southern Illinois. P–T modelling reveals that igneous rocks derive from a deep mantle carbonated source, that is consistent with trace element signatures for a fluorine‐rich transition zone origin. Major element systematics suggests liquid‐immiscibility with lamprophyric melts as the origin for Ca‐carbonatites. Heavy REE (HREE) enrichments in Hicks Dome breccias likely formed through preferential partitioning and transport of HREE by brine‐melts, exsolved from a deep carbonatite body. Brine‐melts redistributed HREEs throughout the system along brecciated pathways where they reprecipitated as HREE‐rich phosphate/fluorcarbonate minerals (e.g. xenotime, florencite, synchesite) in host bedrock. The diversity of igneous rocks in southern Illinois highlights the area as an excellent natural laboratory to study carbonated melt petrogenesis and evolution.
{"title":"Petrologic relationship between lamprophyres, carbonatites, and heavy rare‐earth element enriched breccias at Hicks Dome","authors":"Jarek Trela, Jared T. Freiburg, Esteban Gazel, Laurence Nuelle, Anton H. Maria, David H. Malone, John M. Molinarolo","doi":"10.1111/ter.12712","DOIUrl":"https://doi.org/10.1111/ter.12712","url":null,"abstract":"New petrological, geochemical, and <jats:italic>P</jats:italic>–<jats:italic>T</jats:italic> modelling results from igneous samples clarify how carbonatite‐lamprophyre magmatism, fluorite and rare earth element (REE) enrichment are petrogenetically related in southern Illinois. <jats:italic>P</jats:italic>–<jats:italic>T</jats:italic> modelling reveals that igneous rocks derive from a deep mantle carbonated source, that is consistent with trace element signatures for a fluorine‐rich transition zone origin. Major element systematics suggests liquid‐immiscibility with lamprophyric melts as the origin for Ca‐carbonatites. Heavy REE (HREE) enrichments in Hicks Dome breccias likely formed through preferential partitioning and transport of HREE by brine‐melts, exsolved from a deep carbonatite body. Brine‐melts redistributed HREEs throughout the system along brecciated pathways where they reprecipitated as HREE‐rich phosphate/fluorcarbonate minerals (e.g. xenotime, florencite, synchesite) in host bedrock. The diversity of igneous rocks in southern Illinois highlights the area as an excellent natural laboratory to study carbonated melt petrogenesis and evolution.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"47 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140311339","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}
J. A. Cutts, D. Regis, S. J. Pehrsson, R. Graziani, D. C. Petts, M. A. Smit, B. Knox
Canada's northern cratons record a complex poly‐metamorphic evolution in response to multiple orogenic events. The Snowbird Tectonic Zone (STZ), the principal suture between the Archean Rae and Hearne cratons, is a highly debated structure; it is argued to have accommodated modern‐style accretion in either the Neoarchean (2.6–2.5 Ga) or Palaeoproterozoic (ca. 1.9 Ga). To resolve this controversy, we use Lu–Hf garnet geochronology to date an eclogite collected from the East Athabasca mylonite triangle of the STZ. Garnet shows prograde trace‐element zoning, and we obtained an age of 1914.5 ± 3.4 Ma. The age is interpreted to date the timing of collision related to deep burial of crust along the STZ. This strongly supports Palaeoproterozoic terminal collision between the Rae and Hearne cratons, and that to constrain high‐pressure metamorphism during supercontinent assembly, dating eclogite itself is key.
{"title":"Circa 1.9 Ga Rae‐Hearne collision from Lu–Hf garnet chronology in eclogites","authors":"J. A. Cutts, D. Regis, S. J. Pehrsson, R. Graziani, D. C. Petts, M. A. Smit, B. Knox","doi":"10.1111/ter.12709","DOIUrl":"https://doi.org/10.1111/ter.12709","url":null,"abstract":"Canada's northern cratons record a complex poly‐metamorphic evolution in response to multiple orogenic events. The Snowbird Tectonic Zone (STZ), the principal suture between the Archean Rae and Hearne cratons, is a highly debated structure; it is argued to have accommodated modern‐style accretion in either the Neoarchean (2.6–2.5 Ga) or Palaeoproterozoic (ca. 1.9 Ga). To resolve this controversy, we use Lu–Hf garnet geochronology to date an eclogite collected from the East Athabasca mylonite triangle of the STZ. Garnet shows prograde trace‐element zoning, and we obtained an age of 1914.5 ± 3.4 Ma. The age is interpreted to date the timing of collision related to deep burial of crust along the STZ. This strongly supports Palaeoproterozoic terminal collision between the Rae and Hearne cratons, and that to constrain high‐pressure metamorphism during supercontinent assembly, dating eclogite itself is key.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"49 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140199557","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}
Throughout the Phanerozoic and more, the Earth has experienced cold and hot periods, which are typically associated with long‐lasting (hundreds of million years, Ma) greenhouse and icehouse climate regimes. Now, most published sea‐level curves report two main maxima in the Cretaceous and Ordovician superimposed on a multitude of short‐term fluctuations. The big humps are shown to be predominantly the results of the plate tectonic configuration, not icehouse and greenhouse regimes, suggesting that the small oscillations are related to continental ice variations. From this point of view, it can be inferred that polar ice caps are present almost all the time, and climate regime changes appear much more frequent and shorter than usually considered and are not well‐documented from glaciogenic deposits. Relying on short‐term oscillations, the volume of continental ice can be retrieved over the Phanerozoic.
{"title":"On greenhouse and icehouse climate regimes over the Phanerozoic","authors":"Christian Vérard","doi":"10.1111/ter.12711","DOIUrl":"https://doi.org/10.1111/ter.12711","url":null,"abstract":"Throughout the Phanerozoic and more, the Earth has experienced cold and hot periods, which are typically associated with long‐lasting (hundreds of million years, Ma) greenhouse and icehouse climate regimes. Now, most published sea‐level curves report two main maxima in the Cretaceous and Ordovician superimposed on a multitude of short‐term fluctuations. The big humps are shown to be predominantly the results of the plate tectonic configuration, not icehouse and greenhouse regimes, suggesting that the small oscillations are related to continental ice variations. From this point of view, it can be inferred that polar ice caps are present almost all the time, and climate regime changes appear much more frequent and shorter than usually considered and are not well‐documented from glaciogenic deposits. Relying on short‐term oscillations, the volume of continental ice can be retrieved over the Phanerozoic.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"35 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140152490","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}
We document the complex interaction between metamorphic reactions and deformation behaviour at high-pressure conditions by combining (micro-) structural, petrographical and geochemical data from an eclogite body. The well-equilibrated eclogite fabric is crosscut by mineral veins. Precipitated veins host the eclogitic high-pressure assemblage with variation in modal composition, indicating that fracturing occurred at eclogite facies conditions. Deflection of the eclogite fabric adjacent to the veins implies ductile reactivation of the veins as flanking structures and strain localization under continuous aseismic shearing. In consequence, the reactivated veins are characterized by undulatory extinction and subgrain formation in quartz indicating crystal plasticity. We show that prograde post-eclogitization metamorphism resulted in progressive dehydration and melting of the eclogite. Subsequent increase in pore-pressure-induced rock failure. The mesoscopic to microscopic characteristics of eclogite-facies veins indicate a cyclic behaviour of fracturing, vein formation and crystal-plasticity which demonstrates the strong interaction of chemical and mechanical processes operating at depth.
{"title":"Eclogite dehydration and melt-induced embrittlement at high-pressure conditions","authors":"Anna Rogowitz, Simon Schorn, Benjamin Huet","doi":"10.1111/ter.12707","DOIUrl":"https://doi.org/10.1111/ter.12707","url":null,"abstract":"We document the complex interaction between metamorphic reactions and deformation behaviour at high-pressure conditions by combining (micro-) structural, petrographical and geochemical data from an eclogite body. The well-equilibrated eclogite fabric is crosscut by mineral veins. Precipitated veins host the eclogitic high-pressure assemblage with variation in modal composition, indicating that fracturing occurred at eclogite facies conditions. Deflection of the eclogite fabric adjacent to the veins implies ductile reactivation of the veins as flanking structures and strain localization under continuous aseismic shearing. In consequence, the reactivated veins are characterized by undulatory extinction and subgrain formation in quartz indicating crystal plasticity. We show that prograde post-eclogitization metamorphism resulted in progressive dehydration and melting of the eclogite. Subsequent increase in pore-pressure-induced rock failure. The mesoscopic to microscopic characteristics of eclogite-facies veins indicate a cyclic behaviour of fracturing, vein formation and crystal-plasticity which demonstrates the strong interaction of chemical and mechanical processes operating at depth.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"212 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139765654","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}
The formation of rodingites has been a continually controversial topic, largely due to the absence of minerals that can be unambiguously dated. Here, we present a case study that utilized LA-ICPMS garnet U–Pb dating, in conjunction with field investigations, petrology and Raman spectroscopy, to reveal the age and petrogenesis of rodingite in the northern North China Craton. The rodingites are spatially associated with mafic and alkaline rocks. Our findings indicate that rodingitization occurred at ca. 388 Ma, making it about 5–10 Myr younger than its mafic protoliths, but contemporaneous with the adjoining alkaline plutons. These observations suggest that the rodingitization may be attributed to hydrothermal fluids from the alkaline magmas. Our study emphasizes the importance of utilizing garnet U–Pb dating to determine the timing of rodingitization and introduces a novel perspective on the relationship between rodingitization and alkaline magmas in extensional continental settings.
{"title":"Direct dating rodingitization in the northern North China Craton using garnet U–Pb geochronometry","authors":"Jing Ran, Hao Wang, Jin-Hui Yang, Shi-Tou Wu, Yu-Sheng Zhu, Ya-Dong Wu, Lei Xu, Chao Huang, Bao-Quan Zhou","doi":"10.1111/ter.12708","DOIUrl":"https://doi.org/10.1111/ter.12708","url":null,"abstract":"The formation of rodingites has been a continually controversial topic, largely due to the absence of minerals that can be unambiguously dated. Here, we present a case study that utilized LA-ICPMS garnet U–Pb dating, in conjunction with field investigations, petrology and Raman spectroscopy, to reveal the age and petrogenesis of rodingite in the northern North China Craton. The rodingites are spatially associated with mafic and alkaline rocks. Our findings indicate that rodingitization occurred at ca. 388 Ma, making it about 5–10 Myr younger than its mafic protoliths, but contemporaneous with the adjoining alkaline plutons. These observations suggest that the rodingitization may be attributed to hydrothermal fluids from the alkaline magmas. Our study emphasizes the importance of utilizing garnet U–Pb dating to determine the timing of rodingitization and introduces a novel perspective on the relationship between rodingitization and alkaline magmas in extensional continental settings.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"29 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139765506","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}
F. Mazzarini, L. Bracciali, G. Musumeci, J. R. Wijbrans, K. Kuiper, M. S. A. Horstwood
The late Miocene Monte Capanne and Porto Azzurro plutons are investigated by means of coupled U–Pb zircon and 40Ar/39Ar white mica dating to test the occurrence of long-lived magmatic systems in the upper crust. Zircon crystallized for >1 Ma in both plutonic systems, with supersolidus conditions overlapping for ~220 ka indicating previously unrecognized co-existence of the two reservoirs. The development of the Porto Azzurro high T-aureole is post-dated by continuous igneous zircon crystallization until ~6.0 Ma. By linking crystallization to post-emplacement cooling of late-stage pulses in both western and eastern Elba we constrain long-lived sizeable reservoirs (possibly the same reservoir) in the Tyrrhenian upper crust between ~8 and 6 Ma.
{"title":"Coupled U–Pb and 40Ar/39Ar chronology of late-stage intrusions at Elba Island (Italy) supports late Miocene long-lived magma reservoirs in the Tyrrhenian upper crust","authors":"F. Mazzarini, L. Bracciali, G. Musumeci, J. R. Wijbrans, K. Kuiper, M. S. A. Horstwood","doi":"10.1111/ter.12706","DOIUrl":"https://doi.org/10.1111/ter.12706","url":null,"abstract":"The late Miocene Monte Capanne and Porto Azzurro plutons are investigated by means of coupled U–Pb zircon and <sup>40</sup>Ar/<sup>39</sup>Ar white mica dating to test the occurrence of long-lived magmatic systems in the upper crust. Zircon crystallized for >1 Ma in both plutonic systems, with supersolidus conditions overlapping for ~220 ka indicating previously unrecognized co-existence of the two reservoirs. The development of the Porto Azzurro high T-aureole is post-dated by continuous igneous zircon crystallization until ~6.0 Ma. By linking crystallization to post-emplacement cooling of late-stage pulses in both western and eastern Elba we constrain long-lived sizeable reservoirs (possibly the same reservoir) in the Tyrrhenian upper crust between ~8 and 6 Ma.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"85 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139765544","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}
Vanadium hyper-enrichment (V ≥ 500 μg g−1) is widespread in ancient marine organic-rich sedimentary rocks and is controlled by its source and accumulation. To understand how V source and accumulation control V hyper-enrichment, the V hyper-enriched organic-rich black shales of the Late Devonian–Early Mississippian Bakken Formation (USA) were investigated here. The results imply that V in the Bakken Formation black shales is mainly derived from detritus and open ocean. Its hyper-enrichment was always related to the complexation of V(IV) species by organic matter and/or fine clay mineral adsorption, though extremely reducing (i.e. euxinic) depositional conditions sometimes assisted in accumulating V through forming V(IV)–sulphur structure and/or V(III). Vanadium is a frequently used seawater redox indicator, but its hyper-enrichment in marine sediments/sedimentary rocks does not always need to be redox driven. This study, thus, reminds us to be more careful when reconstructing palaeoceanographic redox states using V-involved proxies.
钒超富集（V≥ 500 μg g-1）在古海洋富有机沉积岩中十分普遍，并受其来源和累积的控制。为了解钒的来源和累积如何控制钒的超富集，本文对美国晚泥盆世-早密西西比世巴肯地层富含钒的有机质黑色页岩进行了研究。研究结果表明，巴肯地层黑色页岩中的 V 主要来源于碎屑和公海。钒的超富集总是与有机质和/或细小粘土矿物吸附络合钒（IV）物种有关，尽管极度还原（即富氧）沉积条件有时通过形成钒（IV）-硫结构和/或钒（III）来帮助钒的累积。钒是一种常用的海水氧化还原指示剂，但钒在海洋沉积物/沉积岩中的过度富集并不一定总是由氧化还原驱动的。因此，这项研究提醒我们在使用钒参与的代用指标重建古海洋氧化还原状态时要更加小心。
{"title":"Refining vanadium hyper-enrichment in black shales of the Late Devonian–Early Mississippian Bakken Formation (USA)","authors":"Yunfeng Wang","doi":"10.1111/ter.12703","DOIUrl":"https://doi.org/10.1111/ter.12703","url":null,"abstract":"Vanadium hyper-enrichment (V ≥ 500 μg g<sup>−1</sup>) is widespread in ancient marine organic-rich sedimentary rocks and is controlled by its source and accumulation. To understand how V source and accumulation control V hyper-enrichment, the V hyper-enriched organic-rich black shales of the Late Devonian–Early Mississippian Bakken Formation (USA) were investigated here. The results imply that V in the Bakken Formation black shales is mainly derived from detritus and open ocean. Its hyper-enrichment was always related to the complexation of V(IV) species by organic matter and/or fine clay mineral adsorption, though extremely reducing (i.e. euxinic) depositional conditions sometimes assisted in accumulating V through forming V(IV)–sulphur structure and/or V(III). Vanadium is a frequently used seawater redox indicator, but its hyper-enrichment in marine sediments/sedimentary rocks does not always need to be redox driven. This study, thus, reminds us to be more careful when reconstructing palaeoceanographic redox states using V-involved proxies.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"24 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139464471","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}
Yin-Zheng Lin, Chuan-Zhou Liu, Henry J. B. Dick, Ross N. Mitchell, Shi-Tou Wu, Tong Liu, Wei-Qi Zhang, Zhen-Yu Zhang
The recycling of subcontinental lithospheric mantle back into the asthenosphere during continental breakup is potentially a major but underappreciated process in plate tectonics. Here, we report major and trace elements for detrital peridotite minerals in carbonate breccias dredged from the Marion Rise, Southwest Indian Ridge. With an emphasis on the trace elements of the relatively abundant orthopyroxene detrital grains, the results show that a portion of pyroxene grains was likely derived from a mantle source that experienced hydrous melting and slab-derived melt metasomatism above a subduction zone. This finding provides a novel view into the mantle geochemistry at midocean ridges, as well as evidence that Marion Rise is at least partially supported by chemically buoyant recycled refractory mantle wedge material.
{"title":"Detrital peridotite minerals reveal recycled arc mantle beneath Marion Rise, Southwest Indian Ridge","authors":"Yin-Zheng Lin, Chuan-Zhou Liu, Henry J. B. Dick, Ross N. Mitchell, Shi-Tou Wu, Tong Liu, Wei-Qi Zhang, Zhen-Yu Zhang","doi":"10.1111/ter.12702","DOIUrl":"https://doi.org/10.1111/ter.12702","url":null,"abstract":"The recycling of subcontinental lithospheric mantle back into the asthenosphere during continental breakup is potentially a major but underappreciated process in plate tectonics. Here, we report major and trace elements for detrital peridotite minerals in carbonate breccias dredged from the Marion Rise, Southwest Indian Ridge. With an emphasis on the trace elements of the relatively abundant orthopyroxene detrital grains, the results show that a portion of pyroxene grains was likely derived from a mantle source that experienced hydrous melting and slab-derived melt metasomatism above a subduction zone. This finding provides a novel view into the mantle geochemistry at midocean ridges, as well as evidence that Marion Rise is at least partially supported by chemically buoyant recycled refractory mantle wedge material.","PeriodicalId":22260,"journal":{"name":"Terra Nova","volume":"29 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139056277","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}
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