佳木斯地块新元古代—早古生代构造—岩浆事件研究

发布时间：2018-06-27 07:02

  本文选题：佳木斯地块 + 新元古代-早古生代　； 参考：《吉林大学》2017年博士论文

【摘要】：本文对佳木斯地块林口-勃利地区和密山地区麻山杂岩中表壳岩及侵入其内的正片麻岩和各类侵入岩,进行了岩石学、锆石LA-ICP-MS和SIMS U-Pb年代学、全岩地球化学及锆石Hf同位素的综合研究,证实了新元古代岩浆作用的存在、并查明其期次、组合及岩石成因,限定了麻粒岩相变质作用的峰期-退变质时间及麻山杂岩中表壳岩的沉积时限,分析了早古生代岩浆作用的成因机制及其与晚泛非期高级变质作用的关系,探讨了佳木斯地块与东冈瓦那大陆Kuunga造山带的亲缘性关系,初步对佳木斯地块可能的时空演化进行了尝试性恢复。密山地区和林口-勃利地区正片麻岩的原岩结晶年龄分别为898~891Ma和757~751Ma,首次明确指示佳木斯地块上至少存在两期新元古代岩浆作用。~895Ma岩浆作用的产物主要为正长花岗岩,具有高硅、高钾、过铝、低Sr/Y的特征,锆石εHf(t)值为-4.2~+0.9(主体为负值),表明其岩浆起源于古老地壳(成熟度可能较高)的部分熔融,在岩浆演化过程中存在新生地壳围岩的混染作用;该期正长花岗岩形成于俯冲相关的挤压-拉张的过渡环境,最可能为Rodinia大陆边缘增生阶段的产物。~752Ma岩浆作用主要形成一套碱长花岗岩、正长花岗岩和二长花岗岩的组合,其具有类A型花岗岩的地球化学特征,锆石饱和温度介于788~845℃,锆石εHf(t)值为-2.8~+4.5(主体为正值),且主、微量元素与SiO2之间具有明显的线性变化关系,表明其主要来源于相对低压环境下的新生地壳物质的部分熔融,并伴有亏损软流圈地幔的热量和物质的双重贡献,在岩浆演化过程中经历了分离结晶作用和古老地壳围岩的混染作用;该期花岗岩属于高分异i型花岗岩,其与兴凯地块~757ma变玄武岩构成双峰式火成岩组合,最可能形成于rodinia裂解机制下的伸展背景。密山地区麻山杂岩中副片麻岩的碎屑锆石年龄介于2548~1064ma,结合~895ma正片麻岩侵入其内的地质事实,表明麻山杂岩中表壳岩的原岩沉积时限为1064~898ma。此外,新元古代正、副片麻岩中记录的谐和变质年龄介于568~476ma,综合考虑锆石成因类型和野外实际观察,可以将其分成两组:其一为569~560ma(~563ma),测自固态重结晶、重置的变质锆石,且其同位素体系基本未遭受后期热事件的扰动,代表了麻粒岩相变质作用的峰期时间;其二为546~476ma,测自固相线生长、亚固相线生长、溶解-再沉淀、重组、重置的变质锆石,其最可能形成于锆石不同程度蜕晶化或后期富流体花岗岩侵位阶段,表明该组年龄反映的是退变质作用的时间。在麻粒岩相变质作用峰期之后,佳木斯地块发生了大规模的早古生代岩浆作用,活动时间为541~476ma(持续~65ma)。该期岩浆作用的产物包括~500ma辉长岩、~515ma石英正长岩和541~476ma花岗闪长岩-二长花岗岩-正长花岗岩。~500ma辉长岩起源于受俯冲流体交代的富集岩石圈地幔的部分熔融,在岩浆演化过程中基本未受到陆壳物质的混染。541~476ma各类花岗质岩石(包括~515ma石英正长岩)属于普通i型或高分异i型花岗岩,具有复杂的地球化学特征,揭示其来源于多个岩浆源区,包括古老地壳物质、新生地壳物质及亏损地幔。i型花岗质岩浆主要起源于相对低压环境下地壳物质的部分熔融,在岩浆形成及演化过程中伴随着亏损地幔岩浆的加入,并遭受了围岩物质的同化混染作用。岩石组合、地球化学特征及麻粒岩相变质作用p-t轨迹的综合分析表明,佳木斯地块541~476ma侵入岩形成于后造山的伸展环境,可能与近等温减压变质阶段后的晚泛非期造山带的垮塌过程密切相关。佳木斯地块和兴凯地块在新元古代-早白垩世(755~115ma)期间经历了相似的岩浆-变质活动,表明它们在地质演化过程中属于同一陆块整体,而中生代敦化-密山断裂不能作为两者之间的构造界线。综合上述研究成果、已发表的区域地质资料及全球范围内的系统对比,认为佳木斯-兴凯地块属于中亚造山带中的外来地体,其不太可能直接来源于西伯利亚、华北或华南克拉通,而与西伯利亚南缘Sayang-Baikal造山带和东冈瓦那Kuunga造山带具有不同程度的可比性。鉴于在新元古代岩浆岩的构造背景、早古生代变质-岩浆作用过程、表壳岩年龄特征及物源组成等方面,佳木斯-兴凯地块与东南极和西澳大利亚更为相似,本文提出在晚泛非期时佳木斯-兴凯地块最可能为Kuunga造山带的一部分,在1000~750Ma期间,其与东南极-澳大利亚一起记录了Rodinia聚合-裂解的演化;而在570~470Ma期间,其又经历了Kuunga造山带从碰撞造山至后造山垮塌的全部过程;之后在470~433Ma的某个时间,佳木斯-兴凯地块从东冈瓦那裂解出来、并向北漂移,直至210~185Ma才在太平洋作用下与与松辽地块完成碰撞拼合,最终就位于中亚造山带东缘。
[Abstract]:In this paper, the lithology, zircon LA-ICP-MS and SIMS U-Pb geochronology, all rock geochemistry and zircon Hf isotopes have been carried out in the Mashan complex of the Jiamusi massif and the Boli and Mishan areas, which have been intruded into the orthopes and various intrusive rocks, which confirmed the existence of the Neoproterozoic magmatism and ascertained its period. The genetic mechanism of the early Palaeozoic magmatism and the relationship with the late Pan African Advanced metamorphism are analyzed, and the relationship between the Jiamusi block and the Kuunga orogenic belt of the East Gondwana continent is discussed. The possible temporal and spatial evolution of the Jiamusi massif was tentatively restored. The original rock age of the primary rock in the Mishan region and the Linkou Boli region was 898~891Ma and 757~751Ma, respectively. It was the first time that there was at least two Neoproterozoic magmatism on the Jiamusi massif. The main product of the ~895Ma magmatism was the long granite. Rock, characterized by high silicon, high potassium, over aluminum, and low Sr/Y, the zircon epsilon Hf (T) value is -4.2~+0.9 (the main body is negative), indicating that the magma originated from the partial melting of the ancient crust (the maturity may be higher), and in the process of magma evolution there was a mixed staining of the surrounding rock of the new crust in the process of magma evolution, and this period of granites was formed by subduction related squeezing and stretching. To ferry the environment, the most likely product of the Rodinia continental margin, the product of.~752Ma magmatism, mainly formed a set of alkali feldspar, the combination of the zigzah granite and two granites, which had the geochemical characteristics of the type A type granite, and the zircon saturation temperature was at 788~845 C, and the value of the zircon epsilon Hf (T) was -2.8~+4.5 (the main body was positive), and the main and trace amounts were trace. There is a clear linear relationship between the element and the SiO2, which indicates that it mainly originates from the partial melting of the new crust material in the relative low pressure environment and the dual contribution of the heat and substance of the mantle of the loss asthenosphere. In the process of magma evolution, the separation and crystallization of the crust is mixed with the ancient crustal surrounding rock, and this period of granite is a granite. The rock belongs to the high Division I type granite, which is composed of the Shuangfeng type igneous rock composed of the ~757ma basalt of Xingkai massif, most likely to be formed in the extension background under the mechanism of Rodinia cracking. The detrital zircon age of the parisnee in the Mishan area of the Mashan complex is between 2548~1064ma and the geological facts of the intrusion of ~895ma gneiss, indicating that Mashan The Proterozoic sedimentary rocks in the complex rocks are limited to 1064~898ma., in Neoproterozoic, and in the consonant metamorphic age recorded in parnegneiss, which can be divided into two groups: one is 569~560ma (~563ma), a solid recrystallization, a resetting metamorphic zircon, and its isotopes. The system basically does not suffer from the disturbance of late thermal events and represents the peak time of granulite facies metamorphism, and the second is 546~476ma, which is measured from solid phase line growth, subsolid phase line growth, dissolving reprecipitation, reorganizing and resetting metamorphic zircon, which is most likely to be formed in the phase of metamorphic crystallization of zircon or in the emplacement stage of late rich fluid granite. The age of the group reflects the time of retrograde metamorphism. After the peak period of the granulite facies metamorphism, a large-scale Early Paleozoic magmatism occurred in the Jiamusi massif, and the activity time was 541~476ma (continuous ~65ma). The products of the magmatism included ~500ma gabbro, ~515ma quartz syenite and 541~476ma granodiorite - two granitic granite. The.~500ma gabbro of the zigzah granite originated from partial melting of the enriched lithospheric mantle under subduction fluid. During the evolution of the magma, the mixture of.541~476ma granitic rocks (including ~515ma quartz syenite), which was not contaminated by the crust material, belonged to the common I or high fractionated I type granites, which had complex geochemical characteristics. It is revealed that it originates from several magmatic source areas, including ancient crustal matter, new crust material and.I type granitic magma of the depleted mantle derived mainly from partial melting of crustal material under the relative low pressure environment, which is accompanied by the addition of the depleted mantle of magma in the process of magma formation and evolution, and has been subjected to assimilation and contamination of rock mass. The comprehensive analysis of rock assemblage, geochemical characteristics and P-T trajectories of granulite facies metamorphism shows that the 541~476ma intrusive rocks in the Jiamusi massif are formed in the extensional environment of the post orogenic belt, which may be closely related to the collapse process of the late pan non phase orogenic belt after the nearly isothermal decompression and metamorphism stage. The Jiamusi and Xingkai blocks are in the Neoproterozoic Early Cretaceous. During the period of 755~115ma, similar magmatic metamorphism has been experienced, indicating that they belong to the same monolithic whole in the process of geological evolution, while the Mesozoic Dunhua Mishan fault can not be used as a tectonic boundary between the two. The results of the study, the published regional geological data and the system comparison in the global scope, are considered to be Jiamusi Xing. The Kay massif belongs to the Central Asian orogenic belt, which is not likely to be directly derived from Siberia, North China or Southern China craton, but with the Sayang-Baikal orogenic belt of the southern margin of Siberia and the East gonzwana Kuunga orogenic belt in varying degrees. The Jiamusi Xingkai block is more similar to the southeast pole and Western Australia in the process, the age characteristics of the crust rock and the source composition of the Jiamusi Xingkai block. This paper suggests that the Jiamusi Xingkai massif is most likely to be part of the orogenic belt in the late Pan African period. In the period of 1000~750Ma, it recorded the Rodinia polymerization cracking together with the southeast pole Australia. In the period of 570~470Ma, the whole process of the evolution of the Kuunga orogenic belt from the collision orogenic to the post orogeny; then, at some time in the 470~433Ma, the Jiamusi Xingkai block broke out from the East Gondwana and moved northward until the 210~185Ma was used to complete the collision with the Songliao block in the Pacific Ocean. The eastern margin of the Central Asian orogenic belt.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P542
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本文编号：2073086