IF 5.8 1区地球科学

Geology Pub Date : 2024-04-01 DOI: 10.1130/g52006c.1

M. Isabel Benito, I. Emma Quijada, Martín Garcia-Martín, Alejandro Pertuz, Pablo Suarez-Gonzalez, Angélica Torices, Sonia Campos-Soto

引用次数: 0

Discovery of Permian–Triassic eclogite in northern Tibet establishes coeval subduction erosion along an ~3000-km-long arc: REPLY 在西藏北部发现的二叠纪-三叠纪蚀变岩确定了沿一条约3000公里长的弧线共生的俯冲侵蚀作用：REPLY

IF 5.8 1区地球科学

Geology Pub Date : 2024-03-01 DOI: 10.1130/g52012y.1

Chen Wu, Andrew V. Zuza, Drew A. Levy, Jie Li, Lin Ding

引用次数: 0

Boninitic melt percolation makes depleted mantle wedges rich in silica: COMMENT 褐铁矿熔体渗流使贫化的地幔楔块富含二氧化硅：评论

IF 5.8 1区地球科学

Geology Pub Date : 2024-03-01 DOI: 10.1130/g51824c.1

Antoine Bénard, Dmitri A. Ionov, Oliver Nebel, Richard J. Arculus

引用次数: 0

Boninitic melt percolation makes depleted mantle wedges rich in silica: REPLY 褐铁矿熔体渗流使贫化的地幔楔块富含二氧化硅：回复

IF 5.8 1区地球科学

Geology Pub Date : 2024-03-01 DOI: 10.1130/g51951y.1

Ming Chen, Jianping Zheng, Hong-Kun Dai, Qing Xiong, Min Sun, Mikhail M. Buslov, Xiang Zhou, Jingao Liu

引用次数: 0

Discovery of Permian–Triassic eclogite in northern Tibet establishes coeval subduction erosion along an ~3000-km-long arc: COMMENT 藏北二叠纪-三叠纪蚀变岩的发现确定了沿约 3000 公里长的弧线共生的俯冲侵蚀：COMMENT

IF 5.8 1区地球科学

Geology Pub Date : 2024-03-01 DOI: 10.1130/g51860c.1

Shuguang Song, Hafiz U. Rehman

引用次数: 0

High-precision U-Pb geochronology links magmatism in the Southwestern Laurentia large igneous province and Midcontinent Rift 高精度 U-Pb 地质年代学将西南劳伦提亚大型火成岩带和中大陆裂谷的岩浆活动联系起来

IF 5.8 1区地球科学

Geology Pub Date : 2024-01-09 DOI: 10.1130/g51786.1

M. Mohr, M. Schmitz, N. Swanson‐Hysell, K.E. Karlstrom, F.A. Macdonald, M. E. Holland, Y. Zhang, N.S. Anderson

{"title":"High-precision U-Pb geochronology links magmatism in the Southwestern Laurentia large igneous province and Midcontinent Rift","authors":"M. Mohr, M. Schmitz, N. Swanson‐Hysell, K.E. Karlstrom, F.A. Macdonald, M. E. Holland, Y. Zhang, N.S. Anderson","doi":"10.1130/g51786.1","DOIUrl":"https://doi.org/10.1130/g51786.1","url":null,"abstract":"The Southwestern Laurentia large igneous province (SWLLIP) comprises voluminous, widespread ca 1.1 Ga magmatism in the southwestern United States and northern Mexico. The timing and tempo of SWLLIP magmatism and its relationship to other late Mesoproterozoic igneous provinces have been unclear due to difficulties in dating mafic rocks at high precision. New precise U-Pb zircon dates for comagmatic felsic segregations within mafic rocks reveal distinct magmatic episodes at ca. 1098 Ma (represented by massive sills in Death Valley, California, the Grand Canyon, and central Arizona) and ca. 1083 Ma (represented by the Cardenas Basalts in the Grand Canyon and a sill in the Dead Mountains, California). The ca. 1098 Ma magmatic pulse was short-lived, lasting 0.25 –0.24 +0.67 m.y., and voluminous and widespread, evidenced by the ≥100 m sills in Death Valley, the Grand Canyon, and central Arizona, consistent with decompression melting of an upwelling mantle plume. The ca. 1083 Ma magmatism may have been generated by a secondary plume pulse or post-plume lithosphere extension.\u0000 The ca. 1098 Ma pulse of magmatism in southwestern Laurentia occurred ∼2 m.y. prior to an anomalous renewal of voluminous melt generation in the Midcontinent Rift of central Laurentia that is recorded by the ca. 1096 Ma Duluth Complex layered mafic intrusions. Rates of lateral plume spread predicted by mantle plume lubrication theory support a model where a plume derived from the deep mantle impinged near southwestern Laurentia, then spread to thinned Midcontinent Rift lithosphere over ∼2 m.y. to elevate mantle temperatures and generate melt. This geodynamic hypothesis reconciles the close temporal relationships between voluminous magmatism across Laurentia and provides an explanation for that anomalous renewal of high magmatic flux within the protracted magmatic history of the Midcontinent Rift.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"49 11","pages":""},"PeriodicalIF":5.8,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139442155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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

A Bayesian astrochronology for the Cambrian first occurrence of trilobites in West Gondwana (Morocco) 西冈瓦纳（摩洛哥）寒武纪首次出现三叶虫的贝叶斯天体年代学

IF 5.8 1区地球科学

Geology Pub Date : 2024-01-08 DOI: 10.1130/g51718.1

Matthias Sinnesael, Andrew R. Millard, Martin R. Smith

引用次数: 0

Methane-carbon budget of a ferruginous meromictic lake and implications for marine methane dynamics on early Earth 一个铁质子午流湖的甲烷-碳预算及其对地球早期海洋甲烷动力学的影响

IF 5.8 1区地球科学

Geology Pub Date : 2024-01-05 DOI: 10.1130/g51713.1

Sajjad Akam, Pei-Chuan Chuang, Sergei Katsev, C. Wittkop, Michelle Chamberlain, Andrew W. Dale, Klaus Wallmann, Adam J. Heathcote, E. Swanner

{"title":"Methane-carbon budget of a ferruginous meromictic lake and implications for marine methane dynamics on early Earth","authors":"Sajjad Akam, Pei-Chuan Chuang, Sergei Katsev, C. Wittkop, Michelle Chamberlain, Andrew W. Dale, Klaus Wallmann, Adam J. Heathcote, E. Swanner","doi":"10.1130/g51713.1","DOIUrl":"https://doi.org/10.1130/g51713.1","url":null,"abstract":"The greenhouse gas methane (CH4) contributed to a warm climate that maintained liquid water and sustained Earth’s habitability in the Precambrian despite the faint young sun. The viability of methanogenesis (ME) in ferruginous environments, however, is debated, as iron reduction can potentially outcompete ME as a pathway of organic carbon remineralization (OCR). Here, we document that ME is a dominant OCR process in Brownie Lake, Minnesota (midwestern United States), which is a ferruginous (iron-rich, sulfate-poor) and meromictic (stratified with permanent anoxic bottom waters) system. We report ME accounting for ≥90% and >9% ± 7% of the anaerobic OCR in the water column and sediments, respectively, and an overall particulate organic carbon loading to CH4 conversion efficiency of ≥18% ± 7% in the anoxic zone of Brownie Lake. Our results, along with previous reports from ferruginous systems, suggest that even under low primary productivity in Precambrian oceans, the efficient conversion of organic carbon would have enabled marine CH4 to play a major role in early Earth’s biogeochemical evolution.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"59 3","pages":""},"PeriodicalIF":5.8,"publicationDate":"2024-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139383523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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

Toroidal flow around the Tonga slab moved the Samoan plume during the Pliocene 汤加板块周围的环状流在上新世期间移动了萨摩亚羽流

IF 5.8 1区地球科学

Geology Pub Date : 2024-01-03 DOI: 10.1130/g51588.1

K. Konrad, Matthew G. Jackson, Bernhard Steinberger, A. Koppers, Andrea Marie Balbas, Valerie Finlayson, J. Konter, Allison Price

{"title":"Toroidal flow around the Tonga slab moved the Samoan plume during the Pliocene","authors":"K. Konrad, Matthew G. Jackson, Bernhard Steinberger, A. Koppers, Andrea Marie Balbas, Valerie Finlayson, J. Konter, Allison Price","doi":"10.1130/g51588.1","DOIUrl":"https://doi.org/10.1130/g51588.1","url":null,"abstract":"Age-progressive seamount tracks generated by lithospheric motion over a stationary mantle plume have long been used to reconstruct absolute plate motion (APM) models. However, the basis of these models requires the plumes to move significantly slower than the overriding lithosphere. When a plume interacts with a convergent or divergent plate boundary, it is often deflected within the strong local mantle flow fields associated with such regimes. Here, we examined the age progression and geometry of the Samoa hotspot track, focusing on lava flow samples dredged from the deep flanks of seamounts in order to best reconstruct when a given seamount was overlying the mantle plume (i.e., during the shield-building stage). The Samoan seamounts display an apparent local plate velocity of 7.8 cm/yr from 0 to 9 Ma, 11.1 cm/yr from 9 to 14 Ma, and 5.6 cm/yr from 14 to 24 Ma. Current fixed and mobile hotspot Pacific APM models cannot reproduce the geometry of the Samoa seamount track if a long-term fixed hotspot location, currently beneath the active Vailulu’u Seamount, is assumed. Rather, reconstruction of the eruptive locations of the Samoan seamounts using APM models indicates that the surface expression of the plume migrated ∼2° northward in the Pliocene. Large-scale mantle flow beneath the Pacific Ocean Basin cannot explain this plume migration. Instead, the best explanation is that toroidal flow fields—generated by westward migration of the Tonga Trench and associated slab rollback—have deflected the conduit northward over the past 2−3 m.y. These observations provide novel constraints on the ways in which plume-trench interactions can alter hotspot track geometries.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"3 4","pages":""},"PeriodicalIF":5.8,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139389517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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

Mechanisms of nitrogen isotope fractionation at an ancient black smoker in the 2.7 Ga Abitibi greenstone belt, Canada 加拿大阿比提比绿岩带 2.7 Ga 古代黑烟炉的氮同位素分馏机制

IF 5.8 1区地球科学

Geology Pub Date : 2024-01-03 DOI: 10.1130/g51689.1

A.N. Martin, E. Stüeken, J.A.-S. Michaud, C. Münker, S. Weyer, E.H.P. van Hees, M.M. Gehringer

{"title":"Mechanisms of nitrogen isotope fractionation at an ancient black smoker in the 2.7 Ga Abitibi greenstone belt, Canada","authors":"A.N. Martin, E. Stüeken, J.A.-S. Michaud, C. Münker, S. Weyer, E.H.P. van Hees, M.M. Gehringer","doi":"10.1130/g51689.1","DOIUrl":"https://doi.org/10.1130/g51689.1","url":null,"abstract":"The biological nitrogen (N) cycle on early Earth is enigmatic because of limited data from Archean (meta-)sediments and the potential alteration of primary biotic signatures. Here we further investigate unusual 15N enrichments reported in 2.7 Ga meta-sediments from the Abitibi greenstone belt, Canada, purportedly related to a 15N-enriched Archean atmosphere. Given that sediments from this region are contemporaneous with large-scale volcanogenic massive sulfide deposits, we utilize Cu and Zn contents to trace the effects of hydrothermal circulation on N isotope fractionation. We show that high δ15Nbulk values as high as +23‰ are associated with Cu-Zn mineralization, whereas unmineralized organic-rich shales exhibit much lower δ15Nbulk and δ15Nkerogen values. Moreover, we find a large offset between δ15Nbulk and δ15Nkerogen of as much as 17‰ and relate this to the addition of organic-bound N during the late-stage emplacement of organic-rich veins. We conclude that the previously reported high δ15N values are most parsimoniously explained by biotic and abiotic mechanisms rather than a 15N-enriched atmosphere. Crucially, both mechanisms require the presence of NH4+ in hydrothermal fluids, supporting the hypothesis that hydrothermal discharge was an important nutrient source for Neoarchean marine life.","PeriodicalId":12642,"journal":{"name":"Geology","volume":"13 24","pages":""},"PeriodicalIF":5.8,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139389571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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

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