The End-Permian mass extinction(EPME),Earth’s most severe biocrisis,occurred proximal to the Permian-Triassic Boundary(PTB),with marine ecosystems experiencing catastrophic collapse.This study employs stable carbon(...The End-Permian mass extinction(EPME),Earth’s most severe biocrisis,occurred proximal to the Permian-Triassic Boundary(PTB),with marine ecosystems experiencing catastrophic collapse.This study employs stable carbon(δ^(13)C)and oxygen isotopes from marine carbonates in the Haidai Section(Xuanwei,northeastern Yunnan)to decipher paleoenvironmental drivers.The well-preserved stratigraphic sequence encompasses the Upper Permian(Yangxin and Xuanwei Formations)transitioning into the Lower Triassic(Feixianguan and Jialingjiang Formations),providing a continuous marine sedimentary archive.A marked negativeδ^(13)C excursion(-9.66‰V-PDB)occurs at the PTB,initiating from+0.82‰with subsequent gradual recovery.This geochemical signature correlates with:90%reduction in primary productivity Biodiversity collapse exhibiting cluster extinction patterns Prolonged suppression of ecological recovery Concurrently,reconstructed seawater temperatures reveal extreme thermal fluctuations,surging from 23℃to 32℃at the PTB before precipitously declining to 16℃.These perturbations demonstrate coupled biogeochemical dynamics wherein:•Carbon cycle destabilization disrupted nutrient fluxes.•Temperature oscillations exceeded marine taxa thermal tolerances.•Synergistic environmental stresses amplified extinction selectivity.Theδ^(13)C-temperature covariance(r^(2)=0.085)establishes mechanistic linkages between physicochemical perturbations and biotic responses.Our findings demonstrate that the EPME was driven by positive feedback loops in which:Volcanic CO₂emissions triggered carbonate saturation decline Thermal stratification exacerbated anoxia Biogeochemical cycling perturbations suppressed primary producers This integrated geochemical record from the Haidai Section provides critical insights into environment-organism coevolution during Phanerozoic Earth’s most profound mass extinction.展开更多
峨眉山大火成岩省(ELIP)主要由玄武岩、玄武质火山碎屑岩及少量的苦橄岩(包括越南的科马提岩)、长英质岩石以及层状岩体和岩墙组成,其物质来源直接关系到其成因是否与地幔柱活动有关。Re-Os 同位素体系是地核、地幔和地壳物质的最佳示...峨眉山大火成岩省(ELIP)主要由玄武岩、玄武质火山碎屑岩及少量的苦橄岩(包括越南的科马提岩)、长英质岩石以及层状岩体和岩墙组成,其物质来源直接关系到其成因是否与地幔柱活动有关。Re-Os 同位素体系是地核、地幔和地壳物质的最佳示踪剂。前人对 ELIP 内的 Re-Os 同位素研究表明,低 Ti 玄武岩的 Os 含量为0.006×10^(-9)～0.400×10^(-9),^(187)Os/^(188)Os 初始值为0.1371～1.403,并提出其与地幔柱活动有关;而高 Ti 玄武岩的 Os 含量为0.004×10^(-9)～0.560×10^(-9),^(187)Os/^(188)Os 初始值为0.1271～5.19,认为起源于大陆岩石圈地幔或地幔柱上升过程中受到大量岩石圈地幔"混染"(Xu JF et al.,2007);科马提岩的 Os 含量为1.24×10^(-9)～7.00×10^(-9),^(187)Os/^(188)Os 初始值为0.1251～0.1261,苦橄岩的 Os 含量为0.32×10^(-9)～2.329×10^(-9),^(187)Os/^(188)Os 初始值为0.1233～0.1266,指示苦橄岩和科马提岩均来自亏损地幔源区(Hanskiet al.,2004;陈雷等,2007)。本文利用 Os 含量最低、^(187)Os/^(188)Os 最高的高 Ti 玄武岩作为地壳端员,用铁质陨石、原始上地幔(PUM)和亏损地幔(DMM)作为地核和各种地幔端员,分别做二元混合计算,结果显示绝大多数玄武岩和所有苦橄岩及科马提岩均落在地壳和 DMM 混合曲线附近,并且邻区特提斯洋地幔岩与 DMM 具有相近的 Os 含量和^(187)Os/^(188)Os 组成,据此推测峨眉山火成岩的形成与特提斯洋的活动有关,主要受控于地壳和亏损地幔的相互作用。展开更多
Compositionally and texturally zoned diabase dykes and sills occur in the outer zone of the Emeishan large igneous province(ELIP) in the southern Guizhou Province,Southwest China. Based on the detailed petrology,whole...Compositionally and texturally zoned diabase dykes and sills occur in the outer zone of the Emeishan large igneous province(ELIP) in the southern Guizhou Province,Southwest China. Based on the detailed petrology,whole rock geochemistry,zircon U-Pb geochronology and Hf isotopes and clinopyroxene mineral compositions studies,we investigate a representative diabase sill in the Luodian region with a view to understanding its petrogenesis and tectonic implications. Formed as composite zoned sub-volcanic intrusion,the diabase sill is characterized by gabbros and diabases in the inner zone and amygdaloidal diabases sporadically in the chilled zone within the upper sill margin. The diabasic and gabbroic rocks are composed of quartz-free and quartz-bearing groups. The quartz-free group rocks have low Si O2(45.7 wt.%–49.5 wt.%),moderate Mg O(5.66 wt.%–7.88 wt.%),high Ti O2(2.54 wt.%–3.65 wt.%),and Ti/Y values(536–747),corresponding to high-Ti type rocks. The quartz-bearing group rocks have higher Si O2(49.8 wt.%–51.7 wt.%) and lower Mg O(4.23 wt.%–4.74 wt.%),higher Ti O2(3.16 wt.%–3.63 wt.%),but lower Ti/Y values(399–419) than the quartz-free group ones,and thus belong to the low-Ti type. Both groups of rocks are enriched in LREE and LILE with negative Nb-Ta anomalies,and show broad tholeiitic affinity. The precursor magma of the high-Ti rocks might have originated from a source composed of mantle plume and subcontinental lithosphere mantle components,with minor crustal contamination during ascending. The magma of the low-Ti rocks was produced by mingling of the high-Ti diabasic rocks with minor injected intermediate-acidic magma plugs or blebs,suggesting magma mingling as one of the effective ways to change the high-Ti to low-Ti rocks of the ELIP. The diabasic sill underwent a rapid cooling event probably in response to a rapid tectonic uplift event,which probably occurred in the waning stage of ELIP during transition between the Middle and Late Permian after the domal uplift induced by the mantle-plume or in the Late Jurassic.展开更多
基金supported by the Scientific Research Fund of the Education Department of Yunnan Province(Grant Number:2019J0488).
文摘The End-Permian mass extinction(EPME),Earth’s most severe biocrisis,occurred proximal to the Permian-Triassic Boundary(PTB),with marine ecosystems experiencing catastrophic collapse.This study employs stable carbon(δ^(13)C)and oxygen isotopes from marine carbonates in the Haidai Section(Xuanwei,northeastern Yunnan)to decipher paleoenvironmental drivers.The well-preserved stratigraphic sequence encompasses the Upper Permian(Yangxin and Xuanwei Formations)transitioning into the Lower Triassic(Feixianguan and Jialingjiang Formations),providing a continuous marine sedimentary archive.A marked negativeδ^(13)C excursion(-9.66‰V-PDB)occurs at the PTB,initiating from+0.82‰with subsequent gradual recovery.This geochemical signature correlates with:90%reduction in primary productivity Biodiversity collapse exhibiting cluster extinction patterns Prolonged suppression of ecological recovery Concurrently,reconstructed seawater temperatures reveal extreme thermal fluctuations,surging from 23℃to 32℃at the PTB before precipitously declining to 16℃.These perturbations demonstrate coupled biogeochemical dynamics wherein:•Carbon cycle destabilization disrupted nutrient fluxes.•Temperature oscillations exceeded marine taxa thermal tolerances.•Synergistic environmental stresses amplified extinction selectivity.Theδ^(13)C-temperature covariance(r^(2)=0.085)establishes mechanistic linkages between physicochemical perturbations and biotic responses.Our findings demonstrate that the EPME was driven by positive feedback loops in which:Volcanic CO₂emissions triggered carbonate saturation decline Thermal stratification exacerbated anoxia Biogeochemical cycling perturbations suppressed primary producers This integrated geochemical record from the Haidai Section provides critical insights into environment-organism coevolution during Phanerozoic Earth’s most profound mass extinction.
文摘峨眉山大火成岩省(ELIP)主要由玄武岩、玄武质火山碎屑岩及少量的苦橄岩(包括越南的科马提岩)、长英质岩石以及层状岩体和岩墙组成,其物质来源直接关系到其成因是否与地幔柱活动有关。Re-Os 同位素体系是地核、地幔和地壳物质的最佳示踪剂。前人对 ELIP 内的 Re-Os 同位素研究表明,低 Ti 玄武岩的 Os 含量为0.006×10^(-9)～0.400×10^(-9),^(187)Os/^(188)Os 初始值为0.1371～1.403,并提出其与地幔柱活动有关;而高 Ti 玄武岩的 Os 含量为0.004×10^(-9)～0.560×10^(-9),^(187)Os/^(188)Os 初始值为0.1271～5.19,认为起源于大陆岩石圈地幔或地幔柱上升过程中受到大量岩石圈地幔"混染"(Xu JF et al.,2007);科马提岩的 Os 含量为1.24×10^(-9)～7.00×10^(-9),^(187)Os/^(188)Os 初始值为0.1251～0.1261,苦橄岩的 Os 含量为0.32×10^(-9)～2.329×10^(-9),^(187)Os/^(188)Os 初始值为0.1233～0.1266,指示苦橄岩和科马提岩均来自亏损地幔源区(Hanskiet al.,2004;陈雷等,2007)。本文利用 Os 含量最低、^(187)Os/^(188)Os 最高的高 Ti 玄武岩作为地壳端员,用铁质陨石、原始上地幔(PUM)和亏损地幔(DMM)作为地核和各种地幔端员,分别做二元混合计算,结果显示绝大多数玄武岩和所有苦橄岩及科马提岩均落在地壳和 DMM 混合曲线附近,并且邻区特提斯洋地幔岩与 DMM 具有相近的 Os 含量和^(187)Os/^(188)Os 组成,据此推测峨眉山火成岩的形成与特提斯洋的活动有关,主要受控于地壳和亏损地幔的相互作用。
基金supported by the Guizhou Scientific and Technology Planning Project (Nos. QKHZDZX [2014]6003, QKHPTRC[2018]5626 and QKH[2016]PTRC5401)
文摘Compositionally and texturally zoned diabase dykes and sills occur in the outer zone of the Emeishan large igneous province(ELIP) in the southern Guizhou Province,Southwest China. Based on the detailed petrology,whole rock geochemistry,zircon U-Pb geochronology and Hf isotopes and clinopyroxene mineral compositions studies,we investigate a representative diabase sill in the Luodian region with a view to understanding its petrogenesis and tectonic implications. Formed as composite zoned sub-volcanic intrusion,the diabase sill is characterized by gabbros and diabases in the inner zone and amygdaloidal diabases sporadically in the chilled zone within the upper sill margin. The diabasic and gabbroic rocks are composed of quartz-free and quartz-bearing groups. The quartz-free group rocks have low Si O2(45.7 wt.%–49.5 wt.%),moderate Mg O(5.66 wt.%–7.88 wt.%),high Ti O2(2.54 wt.%–3.65 wt.%),and Ti/Y values(536–747),corresponding to high-Ti type rocks. The quartz-bearing group rocks have higher Si O2(49.8 wt.%–51.7 wt.%) and lower Mg O(4.23 wt.%–4.74 wt.%),higher Ti O2(3.16 wt.%–3.63 wt.%),but lower Ti/Y values(399–419) than the quartz-free group ones,and thus belong to the low-Ti type. Both groups of rocks are enriched in LREE and LILE with negative Nb-Ta anomalies,and show broad tholeiitic affinity. The precursor magma of the high-Ti rocks might have originated from a source composed of mantle plume and subcontinental lithosphere mantle components,with minor crustal contamination during ascending. The magma of the low-Ti rocks was produced by mingling of the high-Ti diabasic rocks with minor injected intermediate-acidic magma plugs or blebs,suggesting magma mingling as one of the effective ways to change the high-Ti to low-Ti rocks of the ELIP. The diabasic sill underwent a rapid cooling event probably in response to a rapid tectonic uplift event,which probably occurred in the waning stage of ELIP during transition between the Middle and Late Permian after the domal uplift induced by the mantle-plume or in the Late Jurassic.
