华南东北部中生代从挤压向伸展的构造转换
发布时间：2018-08-03 16:05
【摘要】：华南位于古特提斯和滨太平洋两大构造域的交接部位,中生代构造活动复杂,经历了华南板块与华北板块、华南板块与印支板块的陆陆碰撞,以及之后太平洋板块向欧亚板块的俯冲等事件。在华南地区,中生代早期经历了重要的构造转换。印支期表现出的强烈挤压作用,不仅导致了大规模的冲断变形和不整合的发育,同时还伴随岩浆活动和韧性变形；燕山期则表现出强烈的伸展作用,导致了大规模的岩浆作用和北东-北东东走向的断陷盆地发育。因此,本论文以印支期挤压过程和燕山期的伸展过程为突破口,以华南东北部中生代盆地、中生代岩墙群和古老岩石单元为研究对象,以变形分析、热年代学分析、地球化学分析和锆石SHRIMP年代学分析为主要手段,揭示华南东北部构造变形的转换过程。本次研究主要取得了以下几点认识：(1)通过浙赣地区中生代挤压变形特征的分析,以及浙西南地区发育的240Ma糜棱岩和一系列240-220Ma左右的变质岩和同造山花岗岩,表明该地区的印支期变形开始于240Ma左右；这一变形从东南往北西方向传播,在早侏罗世的中晚期传播到江西上饶地区,导致早侏罗世及以前的地层的强烈变形,而传播到江西的萍乡、宜春等地的时间可能在中侏罗世时期。(2)通过浙赣地区中生代盆地的分析,发现浙赣地区的中生代断陷盆地在发育时间上,从内陆逐渐向沿海变晚的特点,弋阳盆地和金衢盆地的开始发育时间大致是在140-135Ma,而到了东部杭嘉湖盆地从100Ma以后才开始发育；但是杭嘉湖盆地的总伸展率达到了30%,而弋阳盆地和金衢盆地的总伸展率只有15%左右,晚白垩世时期的伸展作用要强于早白垩世的伸展作用。白垩纪末,浙赣地区的盆地都存在一个构造反转期,导致了地层的变形和抬升剥蚀。(3)通过陈蔡群杂岩和里浦闪长岩的锆石、磷灰石裂变径迹和热史模拟工作,结合晚三叠世地层的沉积学特征,认为陈蔡群及里浦闪长岩自古生代以来至少经历了三期构造抬升事件才致被剥露至地表,分别为晚三叠世(乌灶组T3w沉积时期)的逆冲推覆、早白垩世(134-105Ma)伸展背景下的相对抬升以及晚白垩世末-古近纪(66-41Ma)的区域整体抬升,并建立了其构造热演化模式。(4)通过江西上饶、浙江诸暨王家宅和浙江丽水枫坪花岗斑岩的研究,并结合前人的研究成果,分析的了浙赣地区岩墙的发育规律。江西上饶中性岩墙为安山玢岩,形成于中侏罗世(160±3Ma),为富铝的亚碱性岩石,具有富集轻稀土元素和大离子亲石元素Th、U和低放射成因Pb,亏损高场强元素Nb、Ti的特点。其球粒陨石标准化曲线呈一致的右倾模式,具轻微Eu负异常,其源区曾受到来自俯冲太平洋板块的脱水作用所致的流体交代作用。王家宅双峰式侵入岩形成于早白垩世(127Ma左右),岩石组合为辉绿岩-花岗斑岩组合,其中辉绿岩为碱性钾玄岩,呈轻稀土元素较富集,重稀土元素平坦的形式,基本无Eu异常(6Eu=0.99-1.09),富集Rb、Ba、Pb及La,亏损Nb、Ta和Ti；花岗斑岩的轻稀土元素含量较辉绿岩大,重稀土元素差别不大,但具弱Eu负异常(δEu=0.85-0.87),富集大离子亲石元素Rb、Ba、Th、Pb、Zr,亏损Nb、Ta,Sr和Ti,具有A型花岗岩的特点。双峰式侵入岩辉绿岩和花岗斑岩的出现标志着区域地壳发生大规模的伸展减薄。丽水枫坪花岗斑岩形成于早白垩世(130+1Ma),具有富硅、铝,碱含量中等,贫锰、镁、钛、磷的特点,其球粒陨石标准化曲线呈向右倾的“海鸥”型且具强Eu负异常,属于典型的地壳重熔型花岗岩。其岩浆源区为华南古老的地壳物质,为富砂质和富泥质的原岩发生部分熔融而成。(5)结合变形特征、盆地和岩墙发育特征、岩浆作用和变质作用特征和古老岩石的剥露过程分析,提出了华南东北部中生代从挤压到伸展的构造转换过程。本文认为华南东北部印支期挤压变形开始于240Ma左右,这一变形从西南往北西方向传播,传播到江西萍乡、宜春等地可能在中侏罗世时期。在160Ma左右,华南东北部地区的构造应力发生了转变,由挤压作用转变为伸展作用。岩石圈的伸展作用首先从江西吉安-上饶地区开始,发育了吉安碱性橄榄玄武岩和上饶安山玢岩等与伸展作用有关的岩浆作用；140Ma左右,华南东北部全面进入伸展构造环境,开始发育断陷盆地、A型花岗岩或碱性侵入岩、变质核杂岩、双峰式火山岩和基性岩墙(群)。140Ma的大规模伸展总体表现从江西吉安-上饶地区往沿海地区迁移,东部沿海地区的大规模伸展集中在110-90Ma。到了晚白垩世时期,华南东北部发生了大规模的构造反转,结束了晚中生代的伸展作用。本论文提出了华南中生代从挤压向伸展转换的时间节点和大陆动力学演化过程,成果对了解区域中生代构造转换有着重要的地质意义。
[Abstract]:Southern China is located in the junction of the two tectonic domains of Gut Tis and the Pacific Ocean, and the Mesozoic tectonic movement is complex. It experienced the continental collision between the Southern China plate and the North China plate, the Southern China plate and the Indo Chinese plate, and the subduction of the Pacific plate to the Eurasian plate. In Southern China, the early Mesozoic experienced an important structural transformation. The strong extrusion effect of the Indosinian period not only resulted in large scale deformation and unconformity, but also accompanied by magmatic activity and ductile deformation, while the Yanshan period showed a strong extension, resulting in large-scale magmatism and the development of a faulted basin in the east to North East and East. Therefore, this paper is Indosinian The period of the extrusion process and the extension process of Yanshan period are the breakthrough. Taking the Mesozoic basin in northeastern Southern China, the Mesozoic rock wall group and the ancient rock unit as the research object, the transformation process of tectonic deformation in Northeast of Southern China is revealed by deformation analysis, thermal chronology analysis, geochemistry analysis and zircon SHRIMP chronology analysis. The main achievements are as follows: (1) through the analysis of the Mesozoic extrusion deformation characteristics of the Zhejiang and Jiangxi areas, and the 240Ma mylonite and a series of 240-220Ma metamorphic and orogenic granites developed in Southwestern Zhejiang, it shows that the Indosinian deformation of the region begins at about 240Ma, and this deformation is from Southeast to North West. Spread to the middle and late stage of the early Jurassic to the Shangrao area of Jiangxi, leading to the strong deformation of the early Jurassic and the previous strata, and the time in Pingxiang and Yichun, Jiangxi, may be in the Middle Jurassic period. (2) through the analysis of Mesozoic basin in Zhejiang Jiangxi region, the Mesozoic fault basin in Zhejiang Jiangxi region was developed in the development time, The development time of the Yiyang basin and Jinqu basin is approximately 140-135Ma, and the development of the eastern hang Jia Lake Basin has been developed only after 100Ma, but the total extension rate of the hang Jia Lake Basin reaches 30%, while the total extension rate of the Yiyang basin and the Jinqu basin is only about 15%, and the late Cretaceous. The extension of the period is stronger than the early Cretaceous extension. At the end of the Cretaceous, there was a tectonic reversal period in the basins in the Zhejiang Jiangxi region, which resulted in the deformation and uplift and denudation of the strata. (3) through the zircon from the Chen Caiqun complex and the Lipu diorite, the apatite fission track and the thermal history model work, combined with the sedimentary characteristics of the late three fold strata. It is considered that Chen Caiqun and Lipu diorite has been exposed to the surface at least three tectonic uplifting events since the Paleozoic, which are the thrust nappe of the late three fold (T3w period), the relative uplift under the early Cretaceous (134-105Ma) extension background and the regional overall uplift of the late Cretaceous and Paleogene (66-41Ma). The tectonic thermal evolution model has been established. (4) through the study of Jiangxi Shangrao, Zhejiang Zhuji Wang house and Lishui Maple granite porphyry in Lishui, Zhejiang, the development law of the rock walls in the Zhejiang and Jiangxi areas is analyzed. The neutral rock wall of Jiangxi Shangrao is an annite porphyrite, which is formed in the Middle Jurassic (160 + 3Ma) and is a subalkaline rock rich in aluminum. There are abundant light rare earth elements and large ion stone elements Th, U and low radiogenic Pb, which have the characteristics of loss of high field and strong element Nb, Ti. The chondrite standardization curve of the chondrites has a consistent right deviation model with a slight negative Eu anomaly, and its source area has been subjected to fluid metasomatism from the dehydration of subducted Pacific plate. Shuangfeng type invasion of Wang Jia residence The rocks are formed in the early Cretaceous (about 127Ma). The rocks are composed of diabase and granite porphyry assemblage. The diabase is alkaline potash basalt, which is enriched in light rare earth elements and is flat in heavy rare earth elements. It is basically without Eu anomaly (6Eu=0.99-1.09), enriches Rb, Ba, Pb and La, loses Nb, Ta and Ti, and the light REE content of granite porphyry is larger than diabase. There is little difference in heavy rare earth elements, but with a weak Eu negative anomaly (delta Eu=0.85-0.87), rich in large ion stone elements Rb, Ba, Th, Pb, Zr, loss Nb, Ta, Sr and Ti, with the characteristics of A type granite. The occurrence of Shuangfeng intrusive diabase and granite porphyry marked the extensive extension and thinning of the regional crust. The Lishui Maple Ping granite porphyry was formed in early white. The Cretaceous (130+1Ma) has the characteristics of rich silicon, aluminum, alkali content, manganese poor, magnesium, titanium and phosphorus. The chondrite standardization curve is a right leaning "Seagull" type and has a strong Eu negative anomaly. It belongs to the typical crustal remelting granite. Its magma source area is the ancient crustal substance in Southern China, which partially melted the sand rich and mud rich rocks. (5) according to the characteristics of deformation, development characteristics of basin and rock wall, characteristics of magmatism and metamorphism and the process of denudation of ancient rocks, the tectonic transformation process from extrusion to extension of Mesozoic in northeastern Southern China is put forward. This paper holds that the Indosinian compression deformation in northeastern Southern China began to be around 240Ma, and this deformation from southwest to North West. The spread to Jiangxi Pingxiang, Yichun and other places may be in the Middle Jurassic period. Around 160Ma, the tectonic stress in the northeastern part of Southern China changed to extension. The extension of the lithosphere started from the Ji'an Shangrao region of Jiangxi, and the Ji'an alkaline olivine basalt and Shangrao porphyrite were bred. The magmatism related to extension and so on; around 140Ma, the northeastern part of Southern China entered the extensional tectonic environment, and began to develop fault basin, A type granite or alkaline intrusive rock, metamorphic core complex, Shuangfeng type volcanic rock and basic rock wall (Group).140Ma extensive extension from Jiangxi Ji'an Shangrao region to coastal area, The large-scale extension of the eastern coastal areas was concentrated from 110-90Ma. to the late Cretaceous period, and a large-scale tectonic reversal occurred in northeastern Southern China, ending the late Mesozoic extension. In this paper, the time node of the Mesozoic transition from extrusion to extension in Southern China and the evolution process of the continental dynamic mechanics were put forward, and the achievements were made to understand the Mesozoic in the region. Structural transformation has important geological significance.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P542
本文编号：2162258
[Abstract]:Southern China is located in the junction of the two tectonic domains of Gut Tis and the Pacific Ocean, and the Mesozoic tectonic movement is complex. It experienced the continental collision between the Southern China plate and the North China plate, the Southern China plate and the Indo Chinese plate, and the subduction of the Pacific plate to the Eurasian plate. In Southern China, the early Mesozoic experienced an important structural transformation. The strong extrusion effect of the Indosinian period not only resulted in large scale deformation and unconformity, but also accompanied by magmatic activity and ductile deformation, while the Yanshan period showed a strong extension, resulting in large-scale magmatism and the development of a faulted basin in the east to North East and East. Therefore, this paper is Indosinian The period of the extrusion process and the extension process of Yanshan period are the breakthrough. Taking the Mesozoic basin in northeastern Southern China, the Mesozoic rock wall group and the ancient rock unit as the research object, the transformation process of tectonic deformation in Northeast of Southern China is revealed by deformation analysis, thermal chronology analysis, geochemistry analysis and zircon SHRIMP chronology analysis. The main achievements are as follows: (1) through the analysis of the Mesozoic extrusion deformation characteristics of the Zhejiang and Jiangxi areas, and the 240Ma mylonite and a series of 240-220Ma metamorphic and orogenic granites developed in Southwestern Zhejiang, it shows that the Indosinian deformation of the region begins at about 240Ma, and this deformation is from Southeast to North West. Spread to the middle and late stage of the early Jurassic to the Shangrao area of Jiangxi, leading to the strong deformation of the early Jurassic and the previous strata, and the time in Pingxiang and Yichun, Jiangxi, may be in the Middle Jurassic period. (2) through the analysis of Mesozoic basin in Zhejiang Jiangxi region, the Mesozoic fault basin in Zhejiang Jiangxi region was developed in the development time, The development time of the Yiyang basin and Jinqu basin is approximately 140-135Ma, and the development of the eastern hang Jia Lake Basin has been developed only after 100Ma, but the total extension rate of the hang Jia Lake Basin reaches 30%, while the total extension rate of the Yiyang basin and the Jinqu basin is only about 15%, and the late Cretaceous. The extension of the period is stronger than the early Cretaceous extension. At the end of the Cretaceous, there was a tectonic reversal period in the basins in the Zhejiang Jiangxi region, which resulted in the deformation and uplift and denudation of the strata. (3) through the zircon from the Chen Caiqun complex and the Lipu diorite, the apatite fission track and the thermal history model work, combined with the sedimentary characteristics of the late three fold strata. It is considered that Chen Caiqun and Lipu diorite has been exposed to the surface at least three tectonic uplifting events since the Paleozoic, which are the thrust nappe of the late three fold (T3w period), the relative uplift under the early Cretaceous (134-105Ma) extension background and the regional overall uplift of the late Cretaceous and Paleogene (66-41Ma). The tectonic thermal evolution model has been established. (4) through the study of Jiangxi Shangrao, Zhejiang Zhuji Wang house and Lishui Maple granite porphyry in Lishui, Zhejiang, the development law of the rock walls in the Zhejiang and Jiangxi areas is analyzed. The neutral rock wall of Jiangxi Shangrao is an annite porphyrite, which is formed in the Middle Jurassic (160 + 3Ma) and is a subalkaline rock rich in aluminum. There are abundant light rare earth elements and large ion stone elements Th, U and low radiogenic Pb, which have the characteristics of loss of high field and strong element Nb, Ti. The chondrite standardization curve of the chondrites has a consistent right deviation model with a slight negative Eu anomaly, and its source area has been subjected to fluid metasomatism from the dehydration of subducted Pacific plate. Shuangfeng type invasion of Wang Jia residence The rocks are formed in the early Cretaceous (about 127Ma). The rocks are composed of diabase and granite porphyry assemblage. The diabase is alkaline potash basalt, which is enriched in light rare earth elements and is flat in heavy rare earth elements. It is basically without Eu anomaly (6Eu=0.99-1.09), enriches Rb, Ba, Pb and La, loses Nb, Ta and Ti, and the light REE content of granite porphyry is larger than diabase. There is little difference in heavy rare earth elements, but with a weak Eu negative anomaly (delta Eu=0.85-0.87), rich in large ion stone elements Rb, Ba, Th, Pb, Zr, loss Nb, Ta, Sr and Ti, with the characteristics of A type granite. The occurrence of Shuangfeng intrusive diabase and granite porphyry marked the extensive extension and thinning of the regional crust. The Lishui Maple Ping granite porphyry was formed in early white. The Cretaceous (130+1Ma) has the characteristics of rich silicon, aluminum, alkali content, manganese poor, magnesium, titanium and phosphorus. The chondrite standardization curve is a right leaning "Seagull" type and has a strong Eu negative anomaly. It belongs to the typical crustal remelting granite. Its magma source area is the ancient crustal substance in Southern China, which partially melted the sand rich and mud rich rocks. (5) according to the characteristics of deformation, development characteristics of basin and rock wall, characteristics of magmatism and metamorphism and the process of denudation of ancient rocks, the tectonic transformation process from extrusion to extension of Mesozoic in northeastern Southern China is put forward. This paper holds that the Indosinian compression deformation in northeastern Southern China began to be around 240Ma, and this deformation from southwest to North West. The spread to Jiangxi Pingxiang, Yichun and other places may be in the Middle Jurassic period. Around 160Ma, the tectonic stress in the northeastern part of Southern China changed to extension. The extension of the lithosphere started from the Ji'an Shangrao region of Jiangxi, and the Ji'an alkaline olivine basalt and Shangrao porphyrite were bred. The magmatism related to extension and so on; around 140Ma, the northeastern part of Southern China entered the extensional tectonic environment, and began to develop fault basin, A type granite or alkaline intrusive rock, metamorphic core complex, Shuangfeng type volcanic rock and basic rock wall (Group).140Ma extensive extension from Jiangxi Ji'an Shangrao region to coastal area, The large-scale extension of the eastern coastal areas was concentrated from 110-90Ma. to the late Cretaceous period, and a large-scale tectonic reversal occurred in northeastern Southern China, ending the late Mesozoic extension. In this paper, the time node of the Mesozoic transition from extrusion to extension in Southern China and the evolution process of the continental dynamic mechanics were put forward, and the achievements were made to understand the Mesozoic in the region. Structural transformation has important geological significance.
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P542
【参考文献】
相关期刊论文 前2条
1 Paul T. ROBINSON;;Discovery of the Indosinian aluminum A-type granite in Zhejiang Province and its geological significance[J];Science China(Earth Sciences);2012年01期
2 陈培荣 ,陆建军 ,范春方 ,华仁民 ,章邦桐;Early Yanshanian post-orogenic granitoids in the Nanling region——Petrological constraints and geodynamic settings[J];Science in China(Series D:Earth Sciences);2002年08期
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