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| 1 | 华北克拉通中东部新太古代晚期变质火山岩及动力学体制显示文摘热状态和壳幔岩浆作用是理解早期地壳形成演化动力学机制的关键。华北克拉通是世界范围内为数不多的保存有大量新太古代晚期(约26~25亿年)变质火山岩记录的克拉通之一,对揭示全球新太古代晚期壳-幔动力学演化过程具有重要的指示意义。在我们研究组近期关于华北克拉通中东部中新太古代热状态和地壳厚度研究基础上,本文收集并整理了726个华北克拉通中东部(包括中部带)新太古代晚期变质火山岩样品的有效地球化学资料。按照现代通用岩石地球化学标准来分类,这些样品主要包括超铁镁质岩石(其中含苦橄岩、苦橄质玄武岩和科马提岩,~7%)、稀土未分异型玄武岩(~14%)、稀土分异型玄武岩(~27%)、玻安岩(~4%)、高镁安山岩(~12%)、低镁安山岩(~26%)和英安岩-流纹岩(~10%)。然而不同区块之间火山岩岩石组合及其量比存在较大差异,其中吉林南部和赞皇等地区以大量稀土分异型玄武岩、高镁和低镁安山岩为主,含有少量的长英质火山岩;胶东、登封和阜新等地区以稀土未分异和稀土分异型玄武岩占有绝对优势,存在少量安山岩和长英质火山岩;冀北、冀东北部、冀东南部(迁安-滦县)、五台-云中山、辽北、辽南和鲁西等地区岩石组合比较复杂,最突出的特点是出现不同比例的玻安岩,组合有稀土未分异和大量稀土分异型玄武岩、高镁和低镁安山岩,出现少量超铁镁质岩石和长英质火山岩。岩石成因研究揭示稀土未分异型和分异型玄武岩、高镁安山岩和玻安岩主要形成于俯冲板片流体、熔体和沉积物熔体交代地幔的部分熔融,而低镁安山岩、英安岩和其它长英质火山岩则大都经历了上述俯冲相关初始岩浆的结晶分异或地壳物质熔融和地壳混染等过程。新太古代晚期胶东地区表现为相对较薄的地壳厚度和较高的地热梯度(18℃/km),而冀东地区表现为厚的地壳厚度和低的地热梯度(最低8.7℃/km),满足现代俯冲地热梯度需求,其它区域的地温梯度介于热俯冲和现代冷俯冲之间。综合以上资料,我们认为新太古代晚期板块构造体制已经是最主要的壳-幔动力学体制,地幔柱构造体制和板块构造-地幔柱联合作用体制可能仍然在局部地区存在,但其作用范围和强度已经明显减小。因此,随着地幔温度的下降,中太古代到新太古代晚期地幔柱和板片俯冲的转化可能是相互关联、此消彼长的动力学过程,而不是一个突变过程。 | 刘树文 包涵 高磊 孙国正 王伟 郭荣荣 郭博然 付敬浩 胡雅璐 白翔 胡方泱 | 2021 | 岩石学报2021，37，1： | 3 |
| 2 | The progressive onset and evolution of Precambrian subduction and plate tectonics显示文摘The regime of plate tectonics on early Earth is one of the fundamental problems in Earth sciences.Precambrian era takes the majority(ca.88%)of Earth’s history and thus plays a key role in understanding the onset of plate tectonics and the mechanism,distribution and process of Precambrian subduction zones.This paper presents a review on the progresses of subduction and subduction zones in different stages of Precambrian era,and sorts out some key issues and fields that merits further attention.We suggest that there was progressive onset and evolution of subduction and plate tectonics from Archean to Proterozoic eras.We emphasize the importance of comprehensive studies on subduction mechanism,metamorphic type,plate tectonics regime,the compositional evolution of continental crust,and petrogenesis of diverse granitoids formed in the Archean.It is proposed that innovative analytical techniques,big data,experimental petrology and numerical geodynamic modeling will facilitate future studies of Precambrian subduction zones. | Xiaolei Wang Fulai Liu Junyong Li Di Wang | 2020 | Science China Earth Sciences2020，63，12： | 1 |
| 3 | Plate Tectonics:The Stabilizer of Earth’s Habitability显示文摘Earth is the only planet known to be habitable,and is also unique with its liquid water,and the operation of plate tectonics.The geological record shows that the habitability of our planet can rapidly recover from major disasters or catastrophes,even those that cause mass extinctions.We suggest that plate tectonics,which acts as a link between the shallow and deep,is pivotal for the formation,evolution,and long-term stability of the hydrosphere,atmosphere,lithosphere,and thus life.Plate tectonics links the surface environment with the deep interior of high viscosity,low Reynolds number,low entropy,and low chaos,able to produce a strong healing effect to neutralize catastrophic events.It can transfer the bio-essential elements from the deep interior to the near-surface environment and can recycle toxic elements to the deep.This unique planetary energy and material transfer process of Earth is a continuous,slow-release,and bidirectional cycle,where a change in the surface is slowly buffered by a reaction from the deep,shaping a long-term and stable habitable environment.Therefore,it is considered that plate tectonics is the basic condition for the long-term stable evolution of the Earth’s biosphere and the stabilizer of the Earth’s habitability. | Zhensheng Wang Junfeng Zhang Keqing Zong Timothy M.Kusky Yanxin Wang | 2023 | Journal of Earth Science2023，34，6： | 0 |
| 4 | Plate tectonics in the Archean:Observations versus interpretations显示文摘Plate tectonics theory,established in the 1960s,has been successful in explaining many geological phenomena,processes and events that occurred in the Phanerozoic.However,the theory has often struggled to provide a coherent framework in interpreting geological records in continental interior and Precambrian period.In dealing with the relationship between plate tectonics and continental geology,continental interior tectonics was often separated from continental margin tectonics in the inheritance and development of their structure and composition.This separation led to the illusion that the plate tectonics theory is not applicable to Precambrian geology,particularly in explaining the fundamental geological characteristics of Archean cratons.Although this illusion does not mean that the Archean continental crust did not originate from a regime of plate tectonics,it led to the development of alternative tectonic models,often involving vertical movements under a regime of stagnant lid tectonics,including not only endogenous processes such as gravitational sagduction,mantle plumes and heat pipes but also exogenous processes such as bolide impacts.These vertical processes were not unique to the Archean but persisted into the Phanerozoic.They result from mantle poloidal convection at different depths,not specific to any particular period.Upgrading the plate tectonics theory from the traditional kinematic model in the 20th century to a holistic kinematic-dynamic model in the 21st century and systematically examining the vertical transport of matter and energy at plate margins,it is evident that plate tectonics can explain the common geological characteristics of Archean cratons,such as lithological associations,structural patterns and metamorphic evolution.By deciphering the structure and composition of convergent plate margins as well as their dynamics,the formation and evolution of continental crust since the Archean can be divided into ancient plate tectonics in the Precambrian and modern plate tectonics in the Phanerozoic.In addition,there are the following three characteristic features in the Archean:(1)convective mantle temperatures were 200–300°C higher than in the Phanerozoic,(2)newly formed basaltic oceanic crust was as thick as 30–40 km,and(3)the asthenosphere had a composition similar to the primitive mantle rather than the depleted mantle at present.On this basis,the upgraded plate tectonics theory can successfully explain the major geological phenomena of Archean cratons.This approach provides a new perspective on and deep insights into the evolution of early Earth and the origin of continental crust.In detail,Archean tonalite-trondhjemite-granodiorite(TTG)rocks would result from partial melting of the over-thick basaltic oceanic crust at convergent plate margins.The structural patterns of gneissic domes and greenstone keels would result from the buoyancy-driven emplacement of TTG magmas and its interaction with the basaltic crust at convergent margins,and komatiites in greenstone belts would be the product of mantle plume activity in the regime of ancient plate tectonics.The widespread distribution of high-grade metamorphic rocks in a planar fashion,rather than in zones,is ascrible to separation of the gneissic domes from the greenstone belts.The shortage of calc-alkaline andesites in bimodal volcanic associations suggests the shortage of sediment accretionary wedges derived from weathering of granitic continental crust above oceanic subduction zones.The absence of Penrose-type ophiolites suggests that during the subduction initiation of microplates,only the upper volcanic rocks of the thick oceanic crust were offscrapped to form basalt accretionary wedges.The absence of blueschist and eclogite as well as classic paired metamorphic belts suggests that convergent plate margins were over-thickened through either warm subduction or hard collision of the thick oceanic crust at moderate geothermal gradients.Therefore,only by correctly recognizing and understanding the nature of Archean cartons can plate tectonics reasonably explain their fundamental geological characteristics. | YongFei ZHENG | 2024 | Science China Earth Sciences2024，67，1： | 0 |
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