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辽西医巫闾山地区瓦子峪变质核杂岩的厘定 总被引：9，自引：0，他引：9
以前未被发现的辽西医巫闾山地区瓦子峪变质核杂岩主要由一条向西倾的低角度正断层———瓦子峪拆离断层组成 ,它将由早白垩世沉积岩和火山岩组成的上盘与糜棱岩化和未变形的下盘分开。瓦子峪拆离断层 (以前称之为孙家湾—稍户营子断裂 )位于变质核杂岩的西侧 ,倾角 10～ 4 0°,构造标志指示向北西方向 (约 2 90°)剪切。与早白垩世地壳伸展相伴生的下盘糜棱岩剪切方向也是北西向 ,这与瓦子峪拆离断层运动相关。已经发表的和未发表的锆石U Pb年龄、40 Ar/3 9Ar热年代学和上盘阜新盆地中生物地层的时代研究表明 ,地壳伸展和变质核杂岩形成时代为早白垩世 (约 12 7～ 116Ma)。我们未发现以前文献报道的医巫闾山是一对称的变质核杂岩的任何证据。瓦子峪变质核杂岩以及WNW侧的拆离断层的厘定会加深我们对华北克拉通早白垩世伸展作用的理解和认识 ,下一步的研究重点包括野外构造研究以确定拆离断层和下盘糜棱岩的空间展布 ,进一步采集样品以研究变质核杂岩的地质 /热年代学和变质核杂岩范围内的岩体成因。我们认为瓦子峪变质核杂岩的形成是太平洋板块边界重组、早白垩世岩浆作用致使地壳升温 ,从而导致经造山作用而加厚的地壳垮塌的结果。 相似文献
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江西庐山地区伸展构造与星子变质核杂岩 总被引：2，自引：0，他引：2
江西庐山地区的伸展构造，是中新生代时期构造变形具有典型特色的系统性构造形迹之一，具有垂向分层，方向分带、空间组合结构有序之特点。其中的星子多期复合变质核杂岩构造、浮船山拆离构造窗、猪岭山滑来峰与盖层内正断层组合及古鄱阳湖盆地等，分别是不同空间部位伸展构造的表现型式。本文着重阐述了上述代表性构造型式的特征，分析了区内伸展构造变形的运动学与动力学特点及形成时代和区域地质构造背景，探讨性寺提出了“走－拉 相似文献
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变质核杂岩的定义、类型及构造背景 总被引：20，自引：6，他引：20
伸展变质核杂岩（mcc）的基本特征包括：（1）缓倾至中等倾角的具有大规模位移的（几十千米）区域信至准区域性延伸的主拆离断层；（2）与断层相关的糜棱片和片麻岩下盘（包括可能出露更深层次的非糜棱化结晶岩）；（3）上盘上地壳基底岩和／或表壳岩层。关键的一点是，所有为质核杂岩是沿地壳深部（大于10－15km）大型拆离断层大规模地壳伸展和地壳切除（缺失）的产物。我们认为，地壳剖面无大规模缺失的以基底为核的穹隆状杂岩不是一般构造定义上公认的变质核杂岩。变质核杂岩形成于同缩短期和缩短期的多种构造环境中。由于前期或同期或缩短的作用，变质杂岩似乎都发育在地壳强烈增厚的区域。绝大多数（但显然并非全部）变质核杂岩都与岩浆作用有密切的时空关系。变质核杂岩起控制作用的拆离断一般生根于中地壳或直接位于石英变为晶质塑性的韧脆性转化带下的深处，但有些拆了断层切穿大部或整个地壳。大多数为质核杂岩总体上具有不对称或简单剪切的构造几何特征，但有些变质核杂岩呈现较为对称的边界拆离断层。 相似文献
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庐山变质核杂岩东侧的星子牛屎墩地区广泛岀露伸展拆离、韧性流变的构造现象,拆离方位为南东方向。该区还岀露一期NNE向左行走滑韧性剪切构造,推测是与郯庐断裂同期变形的构造产物,为郯庐断裂系的一部分。这两期构造运动反映了中生代太平洋构造体制下挤压应力向伸展应力的转换,对伸展滑脱层内同构造的伟晶岩脉及长英质脉的锆石U-Pb年代学测试,结合野外构造现象,以探究该区两期构造性质的转换时限和构造背景。新生变质流体结晶的锆石得到135~140Ma的庐山变质核杂岩拆离带的伸展年龄,内部受热液溶蚀作用的残余锆石得到150.5Ma和153.9Ma的左行剪切变形的年龄。受太平洋构造体制控制,晚侏罗世,该区受板块俯冲作用而处于挤压应力的构造背景,表现为左行剪切构造;早白垩世,在区域性的伸展、减薄作用下,挤压应力向伸展应力转换,庐山变质核杂岩得以形成,其伸展拆离构造是在早期左行剪切构造上的改造与叠加。 相似文献
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新疆若羌县赤石山变质核杂岩研究 总被引：1，自引：0，他引：1
新疆北山裂谷带西缘若羌县赤石山地区存在大型变质核杂岩构造，其下拆离盘为古元古界结晶基底杂岩，上拆离盘为中元古界白湖群变质岩系，滑脱拆离带为已变形的大型韧性正断层，核杂岩南，北侧发育上叠盆地，北侧形成“年轻”正断层及同构造期岩浆岩，变质核杂岩的形成与晚古生代北山陆内裂谷区域伸展有直接联系，该区变质核杂岩的首次厘定，对深化北山裂谷的研究具有重要意义。 相似文献
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熊耳山变质核杂岩构造研究及找矿进展 总被引：5，自引：0，他引：5
豫西熊耳山区是一个在中新生代伸展构造背景中形成的拆离－变质核杂岩构造。其核部由新太古界太华群变质岩系和燕山斯重熔型花岗岩体组成,盖层主要中由元古界熊耳群火山岩系组成。脱拆离系包括位于伏华群和熊耳群之间的主滑脱拆离带和盖层中一系列次级滑脱断层,区内金银矿化在空间分布上受到变质杂岩构造的控制,成矿时代与变质核杂岩主要形成期一致,成矿过程和扩离断层的发展过程一致,拆离断空矿体系可分为６种基本控构造类型, 相似文献
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辽南变质核杂岩具有3层结构,由5部分构成,包括上盘异地岩块与半地堑状伸展盆地、下盘深成变质杂岩与同构造侵入岩体、介于上下盘之间的主拆离断层带共同构成。上盘异地岩块主要为新元古宙与古生界弱变形沉积岩系,岩层经历过印支期前伸展变形作用的改造。伸展盆地在辽南地区规模很小,仅局限于变质核杂岩的局部地段,其中发育了晚白垩世火山-沉积岩系。下盘变质杂岩由太古宙TTG片麻岩系为主,并有少量变质上壳岩系,它们被晚中生代时期同构造就位的二长花岗岩-花岗岩系侵入。拆离断层内发育了记录地壳不同层次拆离作用历史的各种不同类型的构造… 相似文献
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桐柏-大别南缘变质流体变质-变形特征及构造意义 总被引：1，自引：0，他引：1
前人研究认为桐柏山主要是由桐柏核部杂岩单元组成,它是一个早白垩世花岗质片麻岩杂岩体,其中包含一定的三叠纪中高级变质岩石,后期一起经历相同的构造变形过程,在南北两侧形成剪切旋向完全相反的两条大型韧性剪切带,殷店-马垅剪切带就是南边的华南板块由SSE→NNW挤压作用下,在斜切大别造山带的方向上产生的右行平移断裂带。在野外进行地质考察的过程中,发现在该地区变质流体的分布具有一定的规律。因此,本文通过对殷店-马垅剪切带地质特征、走滑性质、糜棱岩及糜棱岩化岩石的变质变形,剪切带内长英质脉体物质组成、变形特征及物质来源等方面研究,探讨剪切带中变质流体的分布规律以及变质变形与变质流体之间的关系。 相似文献
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辽东半岛广泛分布变质核杂岩构造，作为华北克拉通破坏的浅部响应，具有重要的构造演化研究意义.新房变质核杂岩是近年来新发现的伸展构造单元，具备典型的三层结构:上盘主要包括新元古代-古生代弱变形沉积岩层和早白垩世庄河断陷盆地，下盘包括新太古代变质基底和同构造中生代花岗质侵入岩体，二者接触部位为拆离断层带.野外宏观运动学及显微构造特征明显，均指示上盘具由SEE向NWW的运动学特征，与太平洋板块早白垩世早-中期运动方向相吻合.本次工作通过锆石LA-ICP-MS U-Pb同位素及常量、稀土和微量元素测试，将新房变质核杂岩的形成时代大致限定于早白垩世早期（123~125 Ma），并进一步明确为华北克拉通破坏事件的早期产物.该变质核杂岩控制了区内新房大型金矿的生成，在辽东半岛变质核杂岩控矿、成矿较差的现状下，研究意义较大. 相似文献
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张八岭隆起广泛分布的平缓韧性剪切带与郯庐断裂带平移作用形成的陡立韧性剪切带明显不同。通过对平缓韧性剪切带的几何学、运动学分析,结合早白垩世盆地特征、中国东部变质核杂岩伸展拆离断层和同构造岩浆岩同位素定年结果,厘定出张八岭隆起早白垩世变质核杂岩。该变质核杂岩上盘由南华纪-奥陶纪沉积地层和早白垩世盆地组成,下盘为新元古代浅变质碎屑沉积岩、变海相火山岩（基底）以及早白垩世侵入岩,上下盘之间被一条主伸展拆离断层所分隔。变质核杂岩长轴为NE-SW向,指示构造反映上盘向SE剪切滑动,与中国东部变质核杂岩的伸展方向完全一致。通过本次变质核杂岩的厘定,结合野外地质事实,笔者认为管店-马厂断裂是郯庐断裂带的次级断裂,是对郯庐断裂带早白垩世末第三次左行平移的响应。在综合研究的基础上,建立了区域构造-岩浆-成矿关系模型,揭示了张八岭隆起早白垩世经历了早期伸展（变质核杂岩阶段）-挤压走滑（管店-马厂断裂形成阶段）-晚期伸展（闪长质脉岩侵位阶段）3个构造阶段,多期构造、岩浆的叠加作用下,形成了本区的金多金属矿产。 相似文献
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福建蒲洋变质核杂岩构造及其控矿作用初探 总被引：4，自引：0，他引：4
蒲洋变质核杂岩属古大陆边缘型,由变质杂岩核和基底滑脱剥离带组成,因后期构造破坏,褶叠层和未变质盖层出露不齐全,变质杂岩核为加里东期－印支期的中酸性侵入岩,具片麻状构造;基底滑脱剥离带发育于中元古界麻源群变质岩中,具片麻状构造,并在此基础眼育了中浅层次低角度正断层系,肖坂地区金矿床采变质核杂岩生成演化的控制,近核部陡倾角断裂控制石英脉型金矿床,西北侧低角度正断层控制构造蚀变岩金矿床,从构造控矿角度分 相似文献
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《International Geology Review》2012,54(3):254-264
A special metamorphic core complex underlain by a low-angle strike-slip ductile shear zone is present near Chifeng in eastern Inner Mongolia, northern China. The geology of the study area is similar to that of several Cordilleran metamorphic core complexes, but contrasts in significant ways as well. A major ESE-dipping normal fault, the Louzidian Range frontal fault, formed during Late Cretaceous extension. This fault separates a crystalline footwall locally containing mylonitic basement gneisses and granitic rocks (0 to >3 km thick) from a non-metamorphic hanging wall that is distended by normal faults. However, the shear sense of the underlying mylonitic shear zone, a low-angle strike-slip zone, is not compatible with the Louzidian fault. It may be related to a pre-Cretaceous regional sinistral strike-slip event rather than the Late Cretaceous regional crustal extension common throughout eastern China. Pre-existing mylonitic fabric anisotropy appears to have controlled the development of the Louzidian normal fault. Chloritic breccias locally developed along the fault indicate that it cut deeply into the crust of northern China. 相似文献
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黔东地区变质核杂岩构造及其控矿作用 总被引：1，自引：0，他引：1
黔东地区的变质核杂岩构造其变质核杂岩为中元古界四堡群、梵净山群变质基底,其主滑脱面发育于新元古界底部的甲路组,同时在下江群、板溪群中出现一系列次级滑脱面,在其上的早古生代地层中则发育伸展剥离正断层系统。该类型构造形成于加里东期末,是该区加里东造山期后隆升背景的产物。变质核杂岩构造与该地区的金、铜、铅、锌、锑及汞等矿产关系十分密切,它们分别受控于主滑脱带、次级滑脱带及伸展剥离正断层系统,且在剖面上矿物组合、成矿温度出现有规律变化,反映出该地区金及多金属矿产是受控于变质核杂岩构造的一个完整的、相互有机联系的成矿系统。 相似文献
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The article describes the characteristics of the Yagan metamorphic core complex, especially the associated detachment fault and various extensional structures in its footwall. The age of the complex is discussed in some detail as well. The basic features of the Yagan metamorphic complex (Jurassic in age) are similar to those of the metamorphic core complex (Tertiary in age) in the Cordilleran area; they are as follows: (a) mylonitic gneisses in the footwall, (b) chloritized sheared mylonitic rocks, (c) pseudotachylites and flinty cataclasites or microbreccias, (d) unmetamorphosed or epimetamorphic rocks in the hanging wall with a layer of fault gouges or incohesive fault breccia next to the detachment fault. In contrast to its Cordilleran counterpart, however, there are many extensional faults with different styles (from dactile low-angle normal faults through brittle-ductile to brittle high-angle normal faults)in the footwall. 相似文献
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LIU Junlai GUAN Huimei JI Mo CAO Shuyun HU Ling State Key Laboratory of Geological Processes Mineral Resources and Key Laboratory of Lithosphere Tectonics Lithoprobing Technology of the Ministry of Education China University of Geosciences Bei 《《地质学报》英文版》2006,80(4):502-513
The Liaonan metamorphic core complex (mcc) has a three-layer structure and is constituted by five parts, i.e. a detachment fault zone, an allochthonous upper plate and an supradetachment basin above the fault zone, and highly metamorphosed rocks and intrusive rocks in the lower plate. The allochthonous upper plate is mainly of Neoproterozoic and Paleozoic rocks weakly deformed and metamorphosed in pre-Indosinan stage. Above these rocks is a small-scale supradetachment basin of Cretaceous sedimentary and volcanic rocks. The lower plate is dominated by Archean TTG gneisses with minor amount of supracrustal rocks. The Archean rocks are intruded by late Mesozoic synkinematic monzogranitic and granitic plutons. Different types of fault rocks, providing clues to the evolution of the detachment fault zone, are well-preserved in the fault zone, e.g. mylonitic gneiss, mylonites, brecciated mylonites, microbreccias and pseudotachylites. Lineations in lower plate granitic intrusions have consistent orientation that indicate uniform top-to-NW shearing along the main detachment fault zone. This also provides evidence for the synkinematic characteristics of the granitic plutons in the lower plate. Structural analysis of the different parts in the mcc and isotopic dating of plutonic rocks from the lower plate and mylonitic rocks from detachment fault zone suggest that exhumation of the mcc started with regional crustal extension due to crustal block rotation and tangential shearing. The extension triggered magma formation, upwelling and emplacement. This event ended with appearance of pseudotachylite and fault gauges formed at the uppermost crustal level. U-Pb dating of single zircon grains from granitic rocks in the lower plate gives an age of 130±5 Ma, and biotite grains from the mam detachment fault zone have 40Ar-39Ar ages of 108-119 Ma. Several aspects may provide constraints for the exhumation of the Liaonan mcc. These include regional extensional setting, cover/basement contact, temporal and spatial coupling of extension and magmatism, basin development and evolution of fault tectonites along detachment fault zone. We propose that the exhumation of the Liaonan mcc resulted from regional extension and thinning of crust or lithosphere in eastern North China, and accompanied with synkinematic intrusion of granitic plutons, formation of detachment fault zone, uplifting and exhumation of lower-plate rocks, and appearance of supradetachment basin. 相似文献
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WANG Xinshe ZHENG Yadong JIA Wen Department of Earth Space Science Peking University Beijing Institute of Geology Chinese Academy of Geological Science Beijing No. Institute of Geological Resource Exploration of Inner Mongoli Chifeng 《《地质学报》英文版》2004,78(1):237-245
The Louzidian metamorphic core complex (LMCC) in southern Chifeng is located on the northern margin of the North China craton. Structural analyses of the LMCC and its extensional detachment system indicate that the LMCC experienced two-stage extension. The ductile regime experienced top-to-northeast shearing extension and the brittle detachment fault underwent top-down-outwards slipping. Between these two stages, a semi-ductile regime recorded the transition from ductile to brittle. The hanging wall of the detachment fault is similar to those classic supradetachment basins in western North America. Analyses of provenance and paleocurrent directions in the basins show that there were two filling stages. In the early stage, materials came from the southwest margin of the basin and the hanging wall of the detachment system and were transported from southwest to northeast; while in the late stage, deposits were derived from the footwall of the detachment fault and transported outwards to the two sides of the 相似文献