| 胶-辽-吉构造带中段古元古代辽河群早期构造事件(D_1)中构造要素几何学特征及其动力学来源 |
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| 引用本文： | 田忠华,刘利双,董永胜.胶-辽-吉构造带中段古元古代辽河群早期构造事件(D_1)中构造要素几何学特征及其动力学来源[J].岩石学报,2017,33(9):2758-2774. |
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| 作者姓名： | 田忠华 刘利双 董永胜 |
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| 作者单位： | 中国地质科学院地质研究所, 北京 100037,中国地质科学院地质研究所, 北京 100037,吉林大学地球科学学院, 长春 130061 |
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| 基金项目： | 本文受国家自然科学基金重点项目（41430210）、中国地质调查局地质调查项目（DD20160121）和中国地质科学院基本科研业务费项目（J1613、YYWF201703）联合资助. |
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| 摘 要： | 华北克拉通东部陆块中胶-辽-吉构造带在古元古代经历了复杂的变形-变质-岩浆事件。前人工作中,对于辽河群早期构造事件(D_1)的形成背景还存在较大的争议。本文针对辽河群第一期变形(D_1)中产生的各种构造要素,进行了详细的野外构造解析工作。D_1中构造要素主要包括了透入性面理S_1、褶皱F_1及其剪切带SZ_1。其中变泥质岩透入性S1面理劈理域主要由石英、云母、长石和石榴子石等矿物定向排列组成,矿物组合显示了绿片岩相变质作用。F_1褶皱包含了紧闭褶皱、倒转褶皱、鞘褶皱和平卧褶皱等。与D_1相关构造要素的几何学及其运动学特征都指示了D_1形成于挤压环境的动力学背景。此外,研究区辽河群内不仅可以观察到大量的倒转地层,还可见与第一期构造事件(D_1)相关的逆冲断层及其断层相关褶皱,同样指示了D_1形成于挤压环境。结合区域上变质作用和岩浆作用的资料,本研究认为:(1)南、北辽河群中泥质岩及其基性岩都经历了顺时针的P-T-t演化轨迹,M_2变质级别达到了中压环境,过程与地壳的挤压增厚相关,而不是与裂谷过程的低压变质作用相关;(2)花岗岩和基性岩的地球化学和年代学特征显示了胶-辽-吉构造带中段古元古代经历了俯冲作用的影响。综上,辽河群早期构造事件(D_1)受到俯冲挤压的影响,形成于俯冲(造山)背景。
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| 关 键 词： | 古元古代 胶-辽-吉构造带 第一期变形事件D1 挤压环境 俯冲作用 |
| 收稿时间： | 2017/3/10 0:00:00 |
| 修稿时间： | 2017/6/29 0:00:00 |
Geodynamic origin of the earliest tectonic event (D1) and its related structural elements in the Paleoproterozoic Liaohe Group, central Jiao-Liao-Ji structural belt |
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| TIAN ZhongHu,LIU LiShuang and DONG YongSheng.Geodynamic origin of the earliest tectonic event (D1) and its related structural elements in the Paleoproterozoic Liaohe Group, central Jiao-Liao-Ji structural belt[J].Acta Petrologica Sinica,2017,33(9):2758-2774. |
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| Authors: | TIAN ZhongHu LIU LiShuang and DONG YongSheng |
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| Institution: | Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China and College of Earth Sciences, Jilin University, Changchun 130061, China |
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| Abstract: | The Paleoproterozoic Jiao-Liao-Ji Orogenic Belt (JLJOB) in the eastern North China Craton underwent long and multi-stage tectonic-thermal evolution history. The early tectonic event (D1) however received big controversial, this paper therefore mainly focus on field structures related to D1 in the Liaohe Group, central JLJOB. The first stage of deformation D1 contains a penetrative S1 foliation, original bedding (S0) folding fold F1, and early stage shear zone SZ1. The S1 foliation was defined by greenschist facies metamorphic minerals including quartz, muscovite, biotite, chlorite, garnet and feldspar, the F1 contains tight fold, overturned fold, sheath fold and isoclinal fold. All these structures related to S1 indicate a contraction geodynamic stress origin. In addition, strata overturned and thrust fault related to D1 are very common in the Liaohe Group, which also indicate a contraction geodynamic origin. Combined with metamorphic and magmatic data, first, this paper presents that both the South and North Liaohe groups experienced clockwise P-T-t evolution, the stage of M2 arrived middle-pressure metamorphic grade, related to the crust thickening due to the contraction, not to the crust extension by continental rift accompanied by low pressure environment. Secondly, the geochemistry and geochronology of the felsic and mafic magma indicate that the JLJOB might be affected by the Paleoproterozoic subudction. This paper at last proposes that the early tectonic events (D1) of the Liaohe Group formed in a contraction geodynamic setting, related to the Paleoproterozoic subdution or orogensis. |
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| Keywords: | Jiao-Liao-Ji Orogenic Belt (JLJOB) First tectonic event D1 Contraction stress Subduction |
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