| 华北克拉通的组成及其变质演化 |
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| 引用本文：沈其韩,耿元生,宋会侠.2016.华北克拉通的组成及其变质演化[J].地球学报,37(4):387-406. |
| DOI：10.3975/cagsb.2016.04.02 |
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| 基金项目:中国地质调查局工作项目(编号: 1212010811048) |
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| 中文摘要:华北克拉通早前寒武纪变质基底主要由五套不同类型的变质岩系组成。克拉通在形成过程中经历了多期构造活动、多期岩浆侵位、多期变质作用以及不同程度的混合岩化和深熔作用, 岩石已遭受多次不同地质作用的叠加改造, 因此华北克拉通具有复杂的演化历史。从太古宙到古元古代末的克拉通形成, 华北克拉通主要经历了五期区域变质作用。鞍山地区的古—中太古代经历了角闪岩相变质作用改造, 尚未获得变质年龄数据。但在TTG岩系中已获得3 560 Ma和3 000~3 300 Ma早期的变质年龄。河南鲁山太华杂岩的中太古代斜长角闪岩中获得2 776~2 792 Ma和2 671~2 651 Ma两期变质作用年龄信息, 代表了新太古代早期的变质作用。新太古代麻粒岩-TTG岩系和新太古代花岗-绿岩系都经历了新太古代晚期—古元古代初的变质作用改造。在古元古代阶段, 在华北克拉通北缘在1 965~1 900 Ma期间发生了中低压/高压麻粒岩相变质, 局部发生超高温变质, 这期变质作用与陆块间的俯冲碰撞及其后的地幔上涌有关。在古元古代晚期 (1 890~1 800 Ma)在华北克拉通的中部及东部的胶—辽—吉带发生了高压麻粒岩相-角闪岩相的区域变质, 代表了陆块间的碰撞拼合过程。不同变质岩系类型经历的变质作用反映了不同的构造背景。太古宙晚期大量的TTG岩系及呈面状分布的中/低压麻粒岩主要出露在华北克拉通的中北部, 普遍具有逆时针的p-T轨迹, 反映了地幔柱底板垫托的构造环境。新太古代的花岗-绿岩系在新太古代晚期—古元古代早期经历的变质作用多为顺时针的p-T演化轨迹, 反映其发生可能与弧后+地幔柱联合作用的构造背景。古元古代晚期的两期变质作用多表现为高压麻粒岩相的顺时针p-T演化轨迹, 反映了不同陆块(地块)之间碰撞拼合的过程, 意味着类似显生宙的板块构造体制已经出现。 |
| 中文关键词:华北克拉通 中低压/高压/超高温变质作用 地幔柱底板垫托 顺时针/逆时针p-T轨迹 碰撞拼合 |
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| Constituents and Evolution of the Metamorphic Basement of the North China Craton |
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| Abstract:Precambrian metamorphic basement of North China Craton (NCC) is composed of five sets of different types of metamorphic rocks. In the formation process, the NCC experienced multiple tectonic activities, multiple magma emplacement, multiple metamorphism, different degrees of migmatization and anatexis. The rocks suffered multiple superposition of different geological processes and, therefore, the NCC has a complicated evolution history. From Archean to Late Paleoproterozoic, the NCC mainly underwent five stages of regional metamorphism. Anshan area experienced amphibolite facies metamorphism in Paleo/Meso-Archean. However, no metamorphic ages have been obtained except 3 560 Ma and 3 000~3 300 Ma metamorphic ages obtained from TTG series. In Lushan Taihua complex of Henan, 2 776~2 792 Ma and 2 671~2 651 Ma metamorphic ages are obtained from Mesoarchean amphibolites, which represent metamorphism in early Neoarchean. Granulites-TTG series and granite-greenstone belt of Neoarchean both experienced metamorphic transformation in late Neoarchean and early Paleoproterozoic. In Paleoproterozoic, on the northern margin of the NCC, L-MP/HP granulite facies metamorphism occurred between 1 965~1 900 Ma and UHT metamorphism appeared locally. This metamorphism is considered to be related to the continental collision and subsequent mantle upwelling. In Late Paleoproterozoic (1 890~1 800 Ma), in the central and eastern NCC, high-pressure granulite facies to amphibolite facies metamorphism occurred in Jiao–Liao–Ji belt, which indicates the collision and collage of continental blocks. Different types of metamorphic rock series experienced different kinds of metamorphism, which reflect different tectonic settings. A large number of late Archean TTG rock series and planar distribution M-LP granulites are mainly located in the central-northern part of NCC. They generally have counterclockwise p-T paths, which reflect mantle plume underplating tectonic setting. Granite-greenstone series of Neoarchean experienced a metamorphism in late Neoarhcean and early Paleoproterozoic with clockwise p-T paths, reflecting a compound tectonic setting of back-arc and mantle plume. Two metamorphic events that occurred in the Late Paleoproterozoic formed high-pressure granulite facies with clockwise p-T paths, reflecting the collision and collage of continental blocks, which means that plate tectonics system similar to Phanerozoic had appeared. |
| keywords:North China Craton M-LP/HP/UHT metamorphism mantle plume underplating p-T paths collision and collage |
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