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Rates of generation and growth of the continental crust

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Geoscience Frontiers 2019年第1期10卷 165-173页

作者： Chris Hawkesworth peter A.cawood Bruno Dhuime School of Earth Sciences University of Bristol School of Earth Atmosphere and Environment Monash University CNRS-UMR 5243 Géosciences Montpellier Université de Montpellier

Models for when and how the continental crust was formed are constrained by estimates in the rates o crustal growth. The record of events preserved in the continental crust is heterogeneous in time with distinctive peaks and troughs of ages for igneous crystallisation, metamorphism, continental margin and mineralisation. For the most part these are global signatures, and the peaks of ages tend to b associated with periods of increased reworking of pre-existing crust, reflected in the Hf isotope ratios o zircons and their elevated oxygen isotope ratios. Increased crustal reworking is attributed to periods o crustal thickening associated with compressional tectonics and the development of supercontinents Magma types similar to those from recent within-plate and subduction related settings appear to hav been generated in different areas at broadly similar times before ~3.0 Ga. It can be difficult to put th results of such detailed case studies into a more global context, but one approach is to consider when plate tectonics became the dominant mechanism involved in the generation of juvenile continental crust The development of crustal growth models for the continental crust are discussed, and a number o models based on different data sets indicate that 65%-70% of the present volume of the continental crus was generated by 3 Ga. Such estimates may represent minimum values, but since ~3 Ga there has been reduction in the rates of growth of the continental crust. This reduction is linked to an increase in th rates at which continental crust is recycled back into the mantle, and not to a reduction in the rates a which continental crust was generated. Plate tectonics results in both the generation of new crust and it destruction along destructive plate margins. Thus, the reduction in the rate of continental crustal growth at ~3 Ga is taken to reflect the period in which plate tectonics became the dominant mechanism b which new continental crust was generated.

关键词： Continental crust growth curves Rates of crustal growth Tectonics

Petrogenesis and tectonic implications of Early Cretaceous andesitic-dacitic rocks,western Qinling(Central China):Geochronological and geochemical constraints

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Geoscience Frontiers 2019年第4期10卷 1507-1520页

作者： Feifei Zhang peter A. cawood Yunpeng Dong Yuejun Wang State Key Laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi’an 710069China Department of Earth Sciences University of St.AndrewsNorth StreetSt.Andrews KY16 9ALUK School of Earth Atmosphere and EnvironmentMonash UniversityMelbourneVictoria 3800Australia Guangdong Provincial Key Lab of Geodynamics and Geohazards School of Earth Sciences and EngineeringSun Yat-sen UniversityGuangzhou 510275China

40Ar/39Ar and zircon U-Pb geochronological and whole-rock geochemical analyses for the Laozanggou intermediate-acidic volcanic rocks from the western Qinling orogenic belt,Central China,constrain their petrogenesis and the nature of the Late Mesozoic lithospheric *** volcanic rocks yield hornblende or whole-rock 40Ar/39Ar plateau ages of 128.3-129.7 Ma and zircon U-Pb age of131.3±1.3 *** exhibit SiO2 of 56.86-66.86 wt.%,K2 O of 0.99-2.46 wt.%and MgO of 1.03-4.47 wt.%,with Mg#of *** are characterized by arc-like geochemical signatures with significant enrichment in LILE and LREE and depletion in *** the samples have enriched Sr-Nd isotopic compositions with initial 87Sr/86Sr ratios ranging from 0.7112 to 0.7149 andεNd(t)values from 10.2 to *** geochemical signatures suggest that these volcanic rocks were derived from enriched lithospherederived magma followed by the assimilation and fractional crystallization(AFC)*** generation of the enriched lithospheric mantle is likely related to the modification of sediment-derived fluid in response to the Triassic subduction/collision event in Qinling orogenic *** early Cretaceous detachment of the lithospheric root provides a reasonable mechanism for understanding the petrogenesis of the Laozanggou volcanic sequence in the western Qinling orogenic belt.

关键词： 40Ar/39Ar and zircon U-Pb geochronology Sr-Nd isotopes Early Cretaceous AFC process Continental lithospheric mantle Western Qinling orogenic belt

Pre-Cryogenian integrative stratigraphy,biotas,and paleogeographical evolution of the Qinghai-Tibetan Plateau and its surrounding areas

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Science China Earth Sciences 2024年第4期67卷 899-918页

作者： Peiyuan HU Qingguo ZHAI Guochun ZHAO peter A.cawood Yue TANG Yiming LIU Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China Department of Earth Sciences University of Hong KongPokfulam RoadHong Kong 999077China State Key Laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi’an 710069China School of Earth Atmosphere&EnvironmentMonash UniversityMelbourneVIC 3800Australia

The composition and geological evolution of pre-Cryogenian material in the Tibetan Plateau and its surrounding areas have played an important role in studying the formation and evolution of early supercontinents on *** paper systematically summarizes the characteristics of pre-Cryogenian sedimentation,paleontology,magmatism,and metamorphism in the Tibetan Plateau and its surrounding *** on existing data,the records of pre-Cryogenian sedimentation and paleontology are mainly concentrated in the Meso-Neoproterozoic,with relatively few records from the Paleoproterozoic or *** oldest geological record is the Hadean detrital zircons in the metamorphosed sedimentary rocks of the Himalaya and Qamdo areas(ca.4.0 Ga).The Tibetan Plateau and surrounding areas preserve records related to the formation and evolution of the Kenor supercraton,and the Columbia,Rodinia,and Gondwana ***-Cryogenian basements can be divided into three types:Tarim-,Yangtze-,and *** Tarim-type basement has a paleogeographic affinity with the northern margins of the Australian and Indian continents and lacks detrital zircon age peaks and magmatic-metamorphic records related to the Rodinia assembly(ca.1.3-0.9 Ga).The Yangtze-type basement records volcanic activity related to global cooling in the latest pre-Cryogenian period and contains Meso-Neoproterozoic stromatolite and micropaleoflora fossils,as well as magmaticmetamorphic records related to Rodinia assembly(ca.1.1-1.0 Ga).The Lhasa-type basement is characterized by Neoproterozoic rift-related sediment records(ca.900 Ma)and high-pressure metamorphic events(ca.650 Ma),with a prominent peak of detrital zircon ages of ca.1.2-1.1 *** is likely to have a paleogeographic affinity with the African continent.

关键词： Tibetan Plateau Pre-Cryogenian Sedimentation Fossils Paleogeographic evolution

Metamorphic rocks and plate tectonics

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Science Bulletin 2020年第12期65卷 968-969,M0003页

作者： peter A.cawood School of Earth Atmosphere and Environment.Monash University MelbourneVic 3800Australia

Our planet is a dynamic system whose evolution has been controlled by complex feedbacks between its solid and surficial components(e.g.,mantle,crust,oceans,atmosphere and biosphere),across a range of temporal and spatial *** the modern Earth,these interactions are controlled by plate tectonics,which involves the horizontal motion of surface plates(i.e.,continental drift and sea-floor spreading)across a series of continuous linked boundaries[1].

关键词：板块构造 mantle Earth

山西五台山-恒山地区晚太古-早元古代若干关键地质问题的再认识:单颗粒锆石离子探针质谱年龄提出的地质制约

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地质科学 2000年第2期35卷 175-184页

作者：王凯怡郝杰 Simon Wilde peter cawood 中国科学院地质研究所岩石圈构造演化开放研究实验室北京100029 School of Applied Geology Curtin University of Technology

大量准确度很高的单颗粒锆石迅谱 (SHRIMP)年代学数据表明 ,五台山 -恒山绿岩带形成于 2 50 0 Ma之前 ,五台山 -恒山绿岩带形成后即与较老的阜平块体拼合。因此 ,该过程中有大量火山 ,深成活动及变质作用 ,是一次重要的造山运动。在 1 8... 详细信息

大量准确度很高的单颗粒锆石迅谱 (SHRIMP)年代学数据表明 ,五台山 -恒山绿岩带形成于 2 50 0 Ma之前 ,五台山 -恒山绿岩带形成后即与较老的阜平块体拼合。因此 ,该过程中有大量火山 ,深成活动及变质作用 ,是一次重要的造山运动。在 1 80 0 Ma之前 ,本区还经历了一次明显的构造热事件 ,主要表现为在地壳较深水平上大规模的冲断作用 ,使原来为不同地壳水平的块体处于同一地壳水平。本文还对原五台群下部层位板峪口组和金岗库组的归属及铁堡不整合面提出了新的看法。

关键词：晚太古代早元古代单颗粒锆石地质年龄

地球演化历史中氧逸度变化对壳幔循环启动、风化和超大陆循环的指示

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Science Bulletin 2024年第1期69卷 97-102页

作者：王瑞邬绍宸 Roberto F.Weinberg William J.Collins peter A.cawood State Key Laboratory of Geological Processes and Mineral Resources Institute of Earth SciencesChina University of GeosciencesBeijing 100083China Frontiers Science Center for Deep-time Digital Earth China University of Geosciences(Beijing)Beijing 100083China School of Earth Atmosphere and EnvironmentMonash UniversityClayton VIC 3800Australia The Institute for Geoscience Research Curtin UniversityPerth WA 6102Australia

We apply a zircon redox index to a global compilation of detrital zircons to track the variation of oxidation state,expressed asΔFMQ,through Earth's *** from I-type rocks,which comprise mantle and crustal igneous protoliths,including tonalite–trondhjemite–granodiorites(TTGs),generally have a high oxidation state(ΔFMQ>0).In contrast,zircons from igneous rocks derived from supracrustal source rocks(S-type)are commonly reduced(ΔFMQ0 over the last 3 *** that the redox state of magmas is independent of crustal thickness and silica variation,and elevated values are likely more closely related to tectonic setting,we suggest that the consistent averageΔFMQ>0 from ca.3.5 Ga onwards relates to recycling of oceanic lithosphere back into the mantle in what eventually became established as subduction *** more reduced magmas associated with sedimentary sources,became established at 2.6 Ga,presumably in response to continental rocks rising above sealevel,and follow peaks of productivity associated with the supercontinent cycle.

关键词： Oxidation state Supercontinent Weathering Subduction Zircon Granite

Isotopic and geochemical constraints for a Paleoproterozoic accretionary orogen in the Borborema Province,NE Brazil:Implications for reconstructing Nuna/Columbia

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Geoscience Frontiers 2022年第5期13卷 267-285页

作者： Lauro Cézar M.de Lira Santos Geysson A.Lages Fabrício A.Caxito Elton L.Dantas peter A.cawood Haroldo M.Lima Felipe Jda Cruz Lima Departamento de Geologia Universidade Federal de PernambucoAv.da ArquiteturaCidade UniversitáriaRecifePEBrazil Serviço Geológico do Brasil-CPRM Av.SulAfogadosRecifePEBrazil CPMTC Instituto de GeociênciasUniversidade Federal de Minas GeraisAv.Pres.Antônio CarlosPampulhaBelo HorizonteMGBrazil Instituto de Geociências Universidade de BrasíliaCampus Universitário Darcy RibeiroAsa NorteBrasíliaDFBrazil School of Earth Atmosphere and EnvironmentMonash UniversityWellington RdClaytonVIC 3800Australia Departamento de Geologia Universidade Federal do CearáCampus do PiciParquelândiaFortalezaCEBrazil

The Alto MoxotóTerrane of the Borborema Province presents a wide exposure of Paleoproterozoic crust,but unlike other continental blocks of South America,its orogenic history is strongly obliterated by late Neoproterozoic *** isotopic and geochemical studies were conducted in mafic-ultramafic(Fazenda Carmo Suite)and granitic-gneissic rocks(Riacho do Navio Suite)within the *** former present zircon U-Pb crystallization ages at ca.2.13 Ga,whereas Sm-Nd data suggests a juvenile origin via melting of early Paleoproterozoic to Archean peridotitic *** data for these rocks are compatible with tholeiitic magmas with some degree of crustal contamination and trace element distribution points to a continental-arc related setting interpreted as remnants of the early stages of *** contrast,the Riacho do Navio Suite was emplaced at ca.2.08 Ga and has highly negativeεNd(t)values indicating crustal *** suite displays calc-alkali to alkali-calcic and ferroan geochemical signatures compatible with Cordilleran *** addition,trace-element distribution as well as discriminant diagrams suggest that the precursor magmas were generated during the later stages of a continental arc or in a syn-collisional *** on our results,we suggest that the studied units might represent missing pieces of a Paleoproterozoic accretionary orogen that formed the crustal framework of the Alto MoxotóTerrane,and that this represents a block associated with assembly of the Nuna/Columbia supercontinent,which is now largely hidden within the Neoproterozoic orogenic belts of West Gondwana.

关键词： Paleoproterozoic accretionary-collisional event Early orogenic and syn-collisional magmatism Paleoproterozoic inlier within West Gondwana Nuna/Columbia Supercontinent

Generation and preservation of continental crust in the Grenville Orogeny

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Geoscience Frontiers 2015年第3期6卷 357-372页

作者： Christopher J.Spencer peter A.cawood Chris J.Hawkesworth Anthony R.Prave Nick M.W.Roberts Matthew S.A.Horstwood Martin J.Whitehouse EIMF Department of Earth and Environmental Sciences University of St Andrews NERC Isotope Geosciences Laboratory British Geological Survey Swedish Museum of Natural History and Nordic Center for Earth Evolution(NordCEE) Edinburgh Ion Microprobe Facility University of Edinburgh

Detrital zircons from modern sediments display an episodic temporal distribution of U-Pb crystallization ages forming a series of ＇peaks＇ and ＇troughs＇. The peaks are interpreted to represent either periods of enhanced generation of granitic magma perhaps associated with mantle overturn and superplume events, or preferential preservation of continental crust during global collisional orogenesis. The close association of those peaks with the assembly of supercontinents implies a causal relationship between collisional orogenesis and the presence of zircon age peaks. Here these two end-member models （episodic periodicity of increased magmatism versus selective preservation during collisional orogenesis） are assessed using U-Pb, Hf, and 0 analysis of detrital zircons from sedimentary successions deposited during the - 1.3-1.1 Ga accretionary, -1.1-0.9 Ga collisional, and 〈 0.9 Ga extensional collapse phases of the Grenville orogenic cycle in Labrador and Scotland. The pre-collisional, accretionary stage provides a baseline of continental crust present prior to orogenesis and is dominated by Archean and Paleoproterozoic age peaks associated with pre-1300 Ma Laurentian geology. Strata deposited during the Grenville Orogeny display similar Archean and Paleoproterozoic detrital populations along with a series of broad muted peaks from - 1500 to 1100 Ma. However, post-collisional sedimentary successions display a dominant age peak between 1085 and 985 Ma, similar to that observed in modern North American river sediments. Zircons within the post-orogenic sedimentary successions have progressively lower EHf and higher -lSO values from - 1800 to - 1200 Ma whereupon they have higher EHf and -3180 within the dominant 1085-985 Ma age peak. Furthermore, the Lu-Hf isotopic profile of the Grenville-related age peak is consistent with significant assimilation and contamination by older crustal material, The timing of this dominant age peak coincides with the peak of metamorphism and

关键词： Zircon Continental crust Grenville Orogeny Crustal preservation

青藏高原及其周边前成冰纪综合地层、生物群与古地理演化

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中国科学：地球科学 2024年第4期54卷 915-935页

作者：胡培远翟庆国赵国春 peter A.cawood 唐跃刘一鸣中国地质科学院地质研究所北京100037 香港大学地球科学系中国香港999077 大陆动力学国家重点实验室西北大学地质学系西安710069 School of Earth Atmosphere&EnvironmentMonash UniversityMelbourneVIC 3800Australia

青藏高原及邻区前成冰纪物质组成及其地质演化过程,在地球早期超大陆形成演化过程的研究中扮演了重要角色.本文系统梳理和总结了青藏高原及邻区前成冰纪沉积岩、古生物、岩浆和变质作用特征.根据现有资料,青藏高原及邻区前成冰纪沉积岩... 详细信息

青藏高原及邻区前成冰纪物质组成及其地质演化过程,在地球早期超大陆形成演化过程的研究中扮演了重要角色.本文系统梳理和总结了青藏高原及邻区前成冰纪沉积岩、古生物、岩浆和变质作用特征.根据现有资料,青藏高原及邻区前成冰纪沉积岩和古生物记录主要集中于中~新元古代,古元古代及更早的记录相对较少,最古老的地质记录为喜马拉雅和昌都地区前寒武纪变质沉积岩中的冥古宙碎屑锆石(约4.0Ga).青藏高原及邻区保存了凯诺兰超级克拉通以及哥伦比亚、罗迪尼亚和冈瓦纳超大陆形成演化过程的记录,其前成冰纪基底可划分为3种类型:塔里木型、扬子型和拉萨型.塔里木型基底与澳大利亚和印度大陆北缘具有古地理亲缘性,且不发育罗迪尼亚超大陆聚合相关的碎屑锆石年龄峰值和岩浆-变质记录(约1.3~0.9Ga);扬子型基底发育与前成冰纪最晚期全球变冷密切相关的火山活动记录,可见中~新元古代叠层石和微古植物化石,以及约1.1~1.0Ga与罗迪尼亚超大陆聚合相关的岩浆-变质作用记录;拉萨型基底发育新元古代早期大陆裂谷沉积记录(约900Ma)和晚期高压变质事件(约650Ma),具有明显的1.2~1.1Ga碎屑锆石年龄峰值,它很可能与非洲大陆具有古地理亲缘性.

关键词：青藏高原前成冰纪沉积地层古生物群古地理演化