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胶东半岛中生代侵入岩浆活动序列及其构造制约 总被引：25，自引：0，他引：25
胶东半岛是我国东部中生代花岗质岩石较为发育的地区。通过对该区中生代侵入岩体高精度年代学数据资料分析，建立了区内中生代花岗质岩石3个显著不同的演化序列：晚三叠世（225~205 Ma）幔源型花岗岩、晚侏罗世（160~150 Ma）地壳重熔型花岗岩和早白垩世（130~105 Ma）壳幔混合型花岗岩。通过与辽东和鲁西–徐淮地区中生代岩浆活动年代学格架的对比分析，探讨了华北东部地区中生代岩石圈构造演化和深部地球动力学过程。指出胶辽地区晚侏罗世（160~150 Ma）地壳重熔型花岗岩记录了华北东部一次重要的岩石圈地壳增厚事件，其区域动力学背景可能与古太平洋板块低角度向亚洲大陆俯冲作用密切相关。正是这次增厚作用导致了早白垩世时期岩石圈拆沉减薄和大规模伸展型花岗质岩浆活动。岩石圈地壳增厚和减薄作用过程主导了中国东部中生代陆内构造应力体制的转换和岩浆活动序列。 相似文献
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华北克拉通东部古太平洋板块俯冲与回撤作用:来自辽西兴城地区晚中生代花岗质岩石的记录与启示 总被引：2，自引：0，他引：2
目前对于华北克拉通东部晚中生代花岗质岩石的成因仍存在地幔柱、加厚/拆沉下地壳部分熔融、俯冲板片脱水导致地壳熔融等不同认识。辽西兴城地区晚中生代花岗质岩石主要由二长花岗岩、石英闪长岩、花岗斑岩和石英正长岩组成,岩浆成因锆石U-Pb同位素定年结果显示岩浆活动主要发生于晚侏罗世(156Ma)、早白垩世早期(139Ma)、早白垩世中期(130～125Ma)。岩石地球化学测试分析结果显示岩石属于高钾钙碱性系列且具有富集K、Pb等大离子亲石元素而相对亏损Nb、Ta、Ti等高场强元素等活动陆缘岩浆岩特点,表明辽西地区晚中生代岩浆活动的发生与俯冲作用有关。晚侏罗世-早白垩世早期(156～139Ma)花岗质岩石地球化学特征与I型花岗岩类似,同时具有富集的Hf同位素组成(εHf(t)=-22.70～-18.66)和古老的Hf同位素二阶段模式年龄(tDM2=2387～2767Ma),其初始岩浆可能来源于古老中上地壳的部分熔融;形成于130Ma的花岗质岩石同样具有与I型花岗岩相类似的岩石地球化学特征,但其Hf同位素组成突变为亏损(εHf(t)=+3.64～+6.22、tDM1=537～969Ma),其初始岩浆起源于新元古代新生地壳物质的部分熔融并混入少量亏损地幔物质组分;形成于125Ma的花岗质岩石为碱性A型花岗岩,岩石地球化学特征与其他岩石有所不同,具有负的εHf(t)值(-17.30～-11.56)和相对古老的Hf同位素二阶段年龄(tDM2=1917～2278Ma),初始岩浆可能起源于较为古老的中下地壳部分熔融并有幔源物质的参与。华北克拉通东部形成于160～139Ma的花岗质岩石具有I型、高钾钙碱性、与埃达克质岩石类似的高Sr/Y、低Y含量特征和富集的Hf同位素组成,而形成于130～120Ma的花岗质岩石具有A型、碱性、与典型岛弧岩浆岩类似的岩石地球化学特征和相对亏损的Hf同位素组成,同时晚中生代岩浆活动具有向洋年轻化的特点,表明华北克拉通东部156～139Ma期间可能受到古太平洋板块的持续俯冲作用,而139～130Ma古太平洋俯冲板片开始回撤,130～125Ma进入古太平洋俯冲板片持续回撤导致的强烈区域伸展作用阶段。古太平洋俯冲板片脱水交代岩石圈地幔并形成幔源岩浆,幔源岩浆不断底侵作用于古老/新生地壳使其发生部分熔融为花岗质岩石提供岩浆来源。 相似文献
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采用LA-ICP-MS方法对郯庐断裂带巢湖—庐江段的晚中生代火山岩进行了锆石U-Pb年代学研究。由6个样品获得的该处火山喷发时间在距今125~93Ma,为早白垩世晚期至晚白垩世初期,经历了32Ma的喷发历史。与附近的庐枞盆地、北大别造山带及北淮阳地区相比,该地火山喷发具有较晚的结束时间,说明岩石圈减薄具有相对强烈的程度和较长的持续时间。93Ma是已知的华北克拉通残留富集岩石圈地幔最晚的岩浆岩年代学记录。锆石的饱和温度计算、岩浆中较低的MgO含量和Mg#值均不支持岩浆由拆沉的下地壳部分熔融形成,岩浆活动的可能成因是壳幔相互作用,岩浆源区具有由幔源向壳源再过渡到幔源的时间演化顺序。这暗示断裂带下强烈的软流圈上涌引起岩石圈地幔的熔融(距今125Ma),随后岩石圈持续的减薄作用导致其内部热流升高,出现了以流纹岩为代表的地热异常背景下地壳源区的部分熔融(距今120Ma),而最终岩石圈强烈减薄背景下的软流圈物质参与岩浆过程可能是晚期幔源岩浆(距今93Ma)的成因。 相似文献
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详细的LA-ICPMS锆石U-Pb年代学研究表明,位于郯庐断裂（郯城—庐江断裂）带上张八岭隆起东侧边界上的滁州火山岩形成于早白垩世,具体年龄为132～116Ma,岩浆具有多期喷发的特点。该岩浆活动中132Ma的喷发年龄是郯庐断裂带上同期钙碱性岩浆最早出现的时间,代表了该断裂带上岩石圈伸展运动的开始时间。尽管滁州火山岩在构造位置上属于扬子克拉通,但岩浆岩中的古老锆石指示岩浆来源于古老的华北克拉通,这一现象可以用大陆碰撞后楔入模型来解释。该火山岩形成于中国东部岩石圈减薄的动力学背景之下,为岩石圈减薄及壳幔相互作用造成的早白垩世大规模岩浆活动的同期产物。与华北克拉通内部的同期火山岩年代学资料相比,断裂带上火山活动具有相对较早的开始时间和较长的演化历史,表明断裂带内岩石圈具有较克拉通内部强烈的减薄程度和长期的减薄历史,这一特点可能与郯庐断裂带于早白垩世初的大规模左行平移有关。 相似文献
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辽东半岛中生代花岗质岩浆作用的年代学格架 总被引：51，自引：4，他引：47
辽东半岛是我国东部中生代花岗质岩石较为发育的地区。传统观点认为,该区花岗岩以三叠-早中侏罗世（印支-早燕山期）为主。采用SHRIMP、TIMS和LA—ICPMS三种方法,对60余个样品中的锆石进行了U—Pb同位素年代学测定。根据这些资料,目前可以将该区中生代花岗质岩浆作用划分为3个阶段：三叠纪（233～212Ma）、侏罗纪（180～156Ma）和早白垩世（131～117Ma）。与以前认识不同的是,区内的花岗质岩石以早白垩世为主。对比华北地台其它地区中生代岩浆作用的年代学格架发现,三叠纪一侏罗纪花岗岩主要出现在华北东部,而早白垩世花岗岩在全区均较发育,这一分布特征为探讨华北中生代地质演化提供了重要信息。 相似文献
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华北克拉通东部中生代岩石圈减薄已经取得了大量进展,相比之下对克拉通中部岩石圈演化认识不足。本文对华北克拉通中部狐偃山杂岩体中科头正长岩进行了锆石U-Pb年代学、主量和微量元素、Sr-Nd-Hf同位素地球化学研究。LA-ICP-MS锆石U-Pb定年结果显示,科头正长岩侵位于早白垩世晚期(～111Ma)。岩石样品均为钾质—超钾质,属于碱性系列岩石。这些岩石相对富集轻稀土,亏损重稀土和中稀土,具有明显的正Eu异常(Eu/Eu~*=1.22～1.96)、富集大离子亲石元素LILE(Rb、Sr、Ba),亏损高场强元素HFSE(Nb、Ta、Ti)。所有岩石样品具有相对高的初始~(87)Sr/~(86)Sr比值(0.7058～0.7062)和低的ε_(Nd)(t)(-10.4～—11.1),ε_(Hf)(t)介于—12.2～—5.2之间。详细的元素和同位素地球化学研究表明科头正长岩的原始岩浆可能来源于富集岩石圈地幔中富金云母的尖晶石二辉橄榄岩源区的部分熔融,岩浆演化过程中经历了地壳混染与结晶分异(AFC)过程。结合华北克拉通中部岩浆资料,将华北克拉通中部早白垩世岩浆作用分为早晚两期:早期(123～135Ma)为岩浆作用高峰期,晚期(～114Ma)为最后一期弱的岩浆期;华北克拉通中部陆下岩石圈地幔是富集的、不均一的,其至少在早白垩世(138～111Ma)一直处于减薄状态。 相似文献
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华北岩石圈减薄的时空不均一特征 总被引：62，自引：2，他引：60
总结了华北中生代基性岩浆活动的年代学资料和中一新生代岩浆的地球化学特征,认为岩浆随时问的演化趋势与岩石圈减薄过程密切相关。根据富集岩石圈地幔来源的岩浆作用持续时间(180～90Ma)认为该区岩石圈减薄时限约为100Ma。这暗示热机械侵蚀可能是华北岩石圈减薄的主要机制。华北东、西部新生代玄武岩岩浆具有相反的演化趋势,显示了该地区岩石圈减薄作用的时空不均一性。 相似文献
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对鲁西郯城蛇纹岩进行锆石LA-ICP-MS U-Pb年代学和全岩微量元素研究。结果为:蛇纹岩中44颗锆石的年龄值可以分为5组,其中岩浆锆石的年龄为古元古代—新太古代(1 815～2 518 Ma)、新元古代(711 Ma、719 Ma)、早白垩世(106～122 Ma)和晚白垩世(78～92 Ma),而变质锆石形成于晚三叠世(225～231 Ma)。郯城蛇纹岩轻重稀土元素分馏不明显,相对富集大离子亲石元素(Ba、Th、U),相对亏损高场强元素(Nb、Zr、Hf),整体上与华北陆块代表古老岩石圈地幔残留的橄榄岩类包体地球化学特征相类似。蛇纹岩的原岩为纯橄岩,是华北陆块东部古老岩石圈地幔的残留。古元古代—新太古代岩浆锆石的存在,代表拆沉的华北陆块基底物质对岩石圈地幔的改造;新元古代岩浆锆石和晚三叠世变质锆石的发育,表明蛇纹岩的原岩受到了由超高压变质作用的俯冲-断离扬子陆壳物质熔融产生的熔体改造;早白垩世和晚白垩世岩浆锆石年龄的出现,与华北陆块东部该时期发育的岩浆作用时间相一致。华北陆块东部岩石圈地幔受到多阶段、不同性质熔体的改造,改造的峰期发生在早白垩世,与华北陆块东部岩石圈发生大规模减薄的峰期时间一致。 相似文献
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《地学前缘(英文版)》2020,11(3):895-914
A section from the Linglong gold deposit on the northwestern Jiaodong Peninsula,East China,containing Late Mesozoic magmatic rocks from mafic and intermediate dikes and felsic intrusions,was chosen to investigate the lithospheric evolution of the eastern North China Craton(NCC).Zircon U-Pb data showed that low-Mg adakitic monzogranites and granodiorite intrusions were emplaced during the Late Jurassic(～145 Ma) and late Early Cretaceous(112-107 Ma),respectively;high-Mg adakitic diorite and mafic dikes were also emplaced during the Early Cretaceous at～139 Ma and ～118 Ma,and 125-145 Ma and 115-120 Ma,respectively.The geochemical data,including whole-rock major and trace element compositions and Sr-Nd-Pb isotopes,imply that the mafic dikes originated from the partial melting of a lithospheric mantle metasomatised through hydrous fluids from a subducted oceanic slab.Low-Mg adakitic monzogranites and granodiorite intrusions originated from the partial melting of the thickened lower crust of the NCC,while high-Mg adakitic diorite dikes originated from the mixing of mafic and felsic melts.Late Mesozoic magmatism showed that lithosphere-derived melts showed a similar source depth and that crust-derived felsic melts originated from the continuously thickened lower crust of the Jiaodong Peninsula from the Late Jurassic to Early Cretaceous.We infer that the lower crust of the eastern NCC was thickened through compression and subduction of the Palaeo-Pacific plate beneath the NCC during the Middle Jurassic.Slab rollback of the plate from ～160 Ma resulted in lithospheric thinning and accompanied Late Mesozoic magmatism. 相似文献
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A review of the geodynamic setting of large-scale Late Mesozoic gold mineralization in the North China Craton: an association with lithospheric thinning 总被引：22，自引：0，他引：22
Abundant gold deposits are distributed along the margins of the North China Craton (NCC). Occurring throughout the Precambrian basement and located in or proximal to Mesozoic granitoids, these deposits show a consistent spatial–temporal association with Late Jurassic–Early Cretaceous magmatism and are characterized by quartz lode or disseminated styles of mineralization with extensive alteration of wall rock. Their ages are mainly Early Cretaceous (130–110 Ma) and constrain a very short period of metallogenesis. Sr–Nd–Pb isotopic tracers of ores, minerals and associated rocks indicate that gold and associated metals mainly were derived from multi-sources, i.e., the wall rocks (Precambrian basement and Mesozoic granites) and associated mafic rocks.Previous studies, including high surface heat flow, uplift and later basin development, slow seismic wave speeds in the upper mantle, and a change in the character of mantle xenoliths sampled by Paleozoic to Cenozoic magmas, have been used to suggest that ancient, cratonic mantle lithosphere was removed from the base of the NCC some time after the Ordovician, and replaced by younger, less refractory lithospheric mantle. The geochemistry and isotopic compositions of the mafic rocks associated with gold mineralization (130–110 Ma) indicate that they were derived from an ancient enriched lithospheric mantle source; whereas, the mafic dikes and volcanic rocks younger than 110 Ma were derived from a relatively depleted mantle source, i.e., asthenospheric mantle. According to their age and sources, relation to magmatism and geodynamic framework, the gold deposits were formed during lithospheric thinning. The removal of lithospheric mantle and the upwelling of new asthenospheric mantle induced partial melting and dehydration of the lithospheric mantle and lower crust due to an increase of temperature. The fluids derived from the lower crust were mixed with magmatic and meteoric waters, and resulted in the deposition of gold and associated metals. 相似文献
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华北克拉通东部中生代高Mg闪长岩——对岩石圈减薄机制的制约 总被引：18，自引：0，他引：18
在华北克拉通东部鲁西—徐淮地区,存在一套辉石闪长岩-二长闪长岩-花岗闪长岩组成的adakitic岩石。锆石SHRI MP和LA-ICP-MS U-Pb定年结果表明它们形成于早白垩世(130~132Ma)。该类岩石具有较高的MgO含量(质量分数为1·46%~9·76%)、高的Mg#值(0·46~0·68)和高的Sr/Y值(主体介于30~52之间,个别高达410)。这些特征类似于由俯冲大洋板片部分熔融形成的adakitic岩石。然而,它们所表现出来的相对较高的87Sr/86Sr初始比值(0·7051~0·7077)和较低的εNd(t)值(-4·43~-15·92)则反映岩浆形成或演化过程中应有陆壳物质的参与。徐淮地区该类岩石中榴辉岩类捕虏体和石榴石捕虏晶的存在和鲁西辉石闪长岩中众多地幔橄榄岩捕虏体的发现,以及这些捕虏体中普遍发育富硅质交代作用,由此可以判定该类岩浆应起源于拆沉下部大陆地壳的部分熔融及其在上升过程中与地幔橄榄岩的反应,石榴石作为残留相。华北克拉通东部早白垩世adakitic岩石的存在以及榴辉岩类捕虏体的年代学表明,中生代早期曾存在一次重要的陆壳加厚过程,之后相继出现的加厚岩石圈的拆沉应是中生代岩石圈减薄的主导机制。 相似文献
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《International Geology Review》2012,54(5):584-606
ABSTRACTAbundant late Mesozoic granitic rocks are widespread in the southern Great Xing’an Range (GXAR), which have attracted much attention due to its significance for the Mesozoic tectonic evolution in the eastern Central Asian Orogenic Belt. However, controversy has still surrounded the late Mesozoic geodynamic switching in the continental margin of east China, especially the spatial and temporal extent of the influence of the Mongol-Okhotsk and Palaeo-Pacific tectonic regimes. In order to better understand the Late Mesozoic evolutionary history of the southern GXAR, a number of geochemical, geochronological, and isotopic data of the granitoids in this region are collected. Magmatism in the southern GXAR can be divided into six phases: Late Carboniferous (325–303 Ma), Early-Middle Permian (287–260 Ma), Triassic (252–220 Ma), Early Jurassic (182–176 Ma), Late Jurassic (154–146 Ma), and Early Cretaceous (145–111 Ma). Mesozoic magmatic activities in the southern GXAR peaked during the Late Jurassic to Early Cretaceous, accompanied by large-scale mineralization. Sr–Nd–Hf isotopic evidence of these granitic rocks suggested they were likely originated from a mixed source composed of lower crust and newly underplated basaltic crust. Assimilation-fractional crystallization (AFC) or crustal contamination possibly occurred in the magma evolution, and a much more addition of juvenile component to the source of the Early Cretaceous granitoids than that of Late Jurassic. The closure of Mongol-Okhotsk ocean and the break-off of the Mongol-Okhotsk oceanic slab at depth in the Jurassic triggered extensive magmatism and related mineralization in this region. The Jurassic intrusive activities was affected by both the subduction of the Palaeo-Pacific plate and the closure of Mongol-Okhotsk ocean. Less influence of the Mongol-Okhotsk tectonic regime on the Early Cretaceous magmatism, whereas, in contrast the Palaeo-Pacific tectonic regime possibly continued into the Cenozoic. 相似文献
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Petrogenesis of Mesozoic High-Mg Diorites in Western Shandong: Evidence from Chronology and Petro-geochemistry 总被引：7，自引：0，他引：7
Yang Chenghai College of Earth Sciences Jilin University Changchun China Bureau of Geology Mineral Resources of Shandong Province Jinan China Xu Wenliang* Yang Debin College of Earth Sciences Jilin University Changchun China Liu Changchun Bureau of Geology Mineral Resources of Shandong Province Jinan China Liu Xiaoming Hu Zhaochu Key Laboratory of Continental Dynamics Northwestern University Xi'an China 《中国地质大学学报(英文版)》2005,16(4)
TheeasternNorthChinacraton(NCC)isanat urallaboratoryforthestudyoftheformationandev olutionaryhistoryoftheMesozoiccontinentallitho sphereduetoitsparticulartectonicpositionandthe Mesozoicigneousrockswidelyoccurringonit(Wangetal.,2005;Gaoetal.,2004;Peietal.,2004;Xu etal.,2004a,b,c,2003a,b,2000,1999;Zhanget al.,2002;Griffinetal.,1998;MenziesandXu,1998).However,thehigh Mgdioritesinwestern Shandonghaveimportantimplicationsinthestudyof therelationshipbetweenMesozoicmagmatismand thenatureoftheli… 相似文献
16.
Timing and source of several Fe-mineralized mafic-ultramaficintrusions in the Damiao area are investigated here by coupling new geochronological and Hf–Fe isotopic data with previous results. Although regarded as a Late Paleoproterozoic assemblage previously, two ～140 Ma intrusions are recognized by zircon U–Pb dating, indicating emplacement of these intrusions from Middle Devonian to Early Cretaceous times. Both Hf and Fe isotopic features lead to the conclusion that distinct mantle components contributed to their magma generation. As the first magmatic phase, the ～395 Ma intrusions were mainly derived from the slightly-enriched SCLM that was prevalent during the Paleozoic. However, asthenospheric material was strongly involved in the formation of the ～215 Ma Gaositai intrusion. Therefore, the initiation of lithospheric destruction in the northern NCC is inferred to have occurred in Late Triassic time, triggered by post-orogenic extension following the ～250 Ma collision between the Siberian Craton and the NCC. The ～140 Ma intrusions originated from a significantly-enriched mantle component probably resided in the predominant slightly-enriched SCLM. This mantle source would have melted in the Late Mesozoic, when the thin lithosphere enabled enhanced heat transfer from the asthenosphere. In summary, these distinct mantle sources of mafic–ultramafic magmatism provide a record of mantle heterogeneity and the gradual upward migration of the lithosphere–asthenosphere boundary during lithospheric destruction. 相似文献
17.
华北燕山带:构造、埃达克质岩浆活动与地壳演化(英文) 总被引：19，自引：6，他引：19
GregoryA．DAVIS 《地学前缘》2003,10(4):373-384
埃达克质火成岩在中国东部,包括燕山带是很常见的,一般认为它们是下地壳不均匀的镁铁质岩石及/或富集的上地幔岩石在高压(≥1.5 GPa)下部分熔融的结果。在燕山带内埃达克岩浆的形成有一个很长的时间(约190～80 Ma),然而岩浆活动的峰期却与约170～130 Ma间有基底岩石卷入的陆壳收缩期相一致。尽管埃达克质岩浆活动的历史很长,但那种把岩浆活动与岩石圈的拆沉效应相联系的模式似乎是不适当的。在该带内,埃达克质与非埃达克质岩浆活动有一部分是同时的,而且在地理分布上也是相间的,这说明了在下地壳和上地幔岩石的部分熔融中成分是相当不均匀的。侏罗纪及白垩纪熔融作用的热源应当是与古太平洋板块俯冲相关的中生代板底垫托的玄武岩浆。除了局部例外,在燕山带,埃达克质岩浆活动的终结和碱性岩浆活动的开始约在130～120 Ma,在此时期收缩作用使东亚大达200万km~2以上的地区发生了NW—SE向的区域性伸展作用。强烈的地壳伸展仅局限于华北克拉通北缘分布的少数几个变质核杂岩中。陆壳的伸展减薄合理地解释了130～120 Ma间发生高压埃达克质熔融条件的终结,尽管还有局部年轻的埃达克火山活动(约120～80Ma)可以在伸展规模有限而厚的地壳依然存在的地区继续出现。燕山区早白垩世的碱性侵入体中的锆石不存在前寒武纪? 相似文献