辽南变质核杂岩韧性拆离带的变形特征、应变与运动学涡度分析
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摘要
辽南变质核杂岩西侧为一NNE走向、NWW倾向的低角度拆离断层带,其中韧性剪切带由位于拆离断层带下部的糜棱岩组成,糜棱岩中所有运动学指向标志都指示上盘向NWW方向的伸展拆离。基于长石的Rf/φ有限应变法,对该糜棱岩进行测量,结果显示糜棱岩的应变强度(Es)介于0.36~1.0之间,平均0.75。付林图解与霍塞克图解显示应变类型为压扁型(罗德参数υ=0.11~0.98)。使用极摩尔圆法与有限应变法测量糜棱岩面理与线理形成时的运动学涡度,其值介于0.74~0.96之间,平均0.85。使用C′法获得的伸展褶劈理C′形成时的运动学涡度介于0.10~0.84之间,平均0.58。依据运动学涡度、有限应变及拆离带的真实厚度,计算获得拆离带的韧性减薄量为130~705 m。综合以上结论,辽南变质核杂岩剪切变形机制是以糜棱岩面理与线理发育为代表的早期单剪为主的一般剪切以及以伸展褶劈理发育为代表的晚期纯剪为主的一般剪切。
The Liaonan metamorphic core complex(MCC) developed a NNE trend, NWW-dipped, low-angle detachment fault. Ductile shear zone occurred in the lower part and mainly consists of mylonitic granitic gneisses, which indicated a top-to-NWW shearing. Finite strain measurement of feldspar strain markers were estimated by the Rf /φ method. It suggested that strain intensities of mylonites(Es) changed from 0.36 to 1.0 with an average of 0.75. Fulin and Hossack diagrams indicated strain types were close to flattening strain(lod parameter υ=0.11-0.98). Kinematic vorticity of mylonitic foliations and stretching lineations were estimated by Mohr diagram method and long and short axis method. The results indicated that kinematic vorticity ranged from 0.74 to 0.96 with an average of 0.85, which suggested that the foliations and lineations of mylonites recorded a bulk simple-dominated general shearing. The Kinematic vorticity during formation of extensional crenulation cleavage estimated by C′ method ranged from 0.10 to 0.84 with 0.58 on average. It recorded a later bulk pure-dominated general shearing. Based on the strain measurement, kinematic vorticity and thickness of the detachment fault, the quantification of thinning for the ductile shearing were calculated, which ranged from 130 to 705 m. All results suggested that the deformation mechanism of the Liaonan MCC was represented by earlier simple-dominated shearing and later pure-dominated shearing.
The Liaonan metamorphic core complex(MCC) developed a NNE trend, NWW-dipped, low-angle detachment fault. Ductile shear zone occurred in the lower part and mainly consists of mylonitic granitic gneisses, which indicated a top-to-NWW shearing. Finite strain measurement of feldspar strain markers were estimated by the Rf /φ method. It suggested that strain intensities of mylonites(Es) changed from 0.36 to 1.0 with an average of 0.75. Fulin and Hossack diagrams indicated strain types were close to flattening strain(lod parameter υ=0.11-0.98). Kinematic vorticity of mylonitic foliations and stretching lineations were estimated by Mohr diagram method and long and short axis method. The results indicated that kinematic vorticity ranged from 0.74 to 0.96 with an average of 0.85, which suggested that the foliations and lineations of mylonites recorded a bulk simple-dominated general shearing. The Kinematic vorticity during formation of extensional crenulation cleavage estimated by C′ method ranged from 0.10 to 0.84 with 0.58 on average. It recorded a later bulk pure-dominated general shearing. Based on the strain measurement, kinematic vorticity and thickness of the detachment fault, the quantification of thinning for the ductile shearing were calculated, which ranged from 130 to 705 m. All results suggested that the deformation mechanism of the Liaonan MCC was represented by earlier simple-dominated shearing and later pure-dominated shearing.
引文
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[16]欧阳志侠,王涛,李建波.辽南金州拆离带糜棱状花岗岩脉体变形特征及锆石SHRIMP U-Pb年龄韧性拆离时限的新证据.岩石矿物学杂志,2010,29(4):403-413
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[19]曾令森,李海兵.辽南金州隆起区构造变形与流体作用.高校地质学报,1996,2(2):155-165
[20]郑亚东,曾令森,李建波,等.辽南中生代造山作用与晚造山伸展垮塌作用.地质科学,2009,44(3):811-824
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[22]De Paor D G.Rf/φf strain analysis using an orientation net.Journal of Structural Geology,1988,10(4):323-333
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[24]张进江,郑亚东.运动学涡度、极摩尔圆及其在一般剪切带定量分析中的应用.地质力学学报,1995,1(3):56-64
[25]张进江,郑亚东.运动学涡度和极摩尔圆的基本原理与应用.地质科技情报,1997,16(3):33-39
[26]Zhang Jinjiang,Zheng Yadong.Polar Mohr constructions of strain analysis in general shear zone.Journal of Structural Geology,1997,19(5):745-748
[27]郑亚东,王涛,张进江.运动学涡度的理论与实践.地学前缘,2008,15(3):209-220
[28]郑亚东,王涛,王新社.世纪构造地质学与力学的新理论:最大有效力矩准则.自然科学进展,2005,15(2):142-148
[29]郑亚东,王涛,王新社.最大有效力矩准则及相关地质构造.地学前缘,2007,14(4):49-60
[30]郑亚东,王涛,王新社.最大有效力矩准则的理论与实践.北京大学学报:自然科学版,2007,43(3):145-156
[31]郑亚东,王涛,王新社.神秘的109.4°:共轭变形带的夹角.地质科学,2007,42(1):1-9
[32]郑亚东,王涛,张进江.运动学涡度的理论与实践.地学前缘,2008,15(3):209-220
[33]Wallis S R,Platt J P,Knott S D.Recognition of sunconvergence extension in accretionary wedges with examples from the Calabrian Arc and the Eastern Alps.American Journal of Science,1993,293:463-495
[34]Tikoff B,Teyssier C.Strain modeling of displacement-field partitioning in transpressional orogens.Journal of Structural Geology,1994,16(11):1575-1588
[35]Coney P J,Harms T A.Cordilleran metamorphic core complexes:Cenozoic extensional relics of Mesozoic compression.Geology,1984,12:550-554
[36]Sonder L J,England P C,Wernicke B P.A physical model for Cenozoic extension of western North America//Coward M P,Dewey J F,Hancock P L.Continental extensional tectonics.Geological Society of London Special Publication,1987,28:187-201
[37]Dewey J F.Extensional collapse of orogens.Tectonics,1988,7:1123-1139
[38]吴福元,杨进辉,张艳斌,等.辽西东南部中生代花岗岩时代.岩石学报,2006,22(2):315-325
[39]Davis G H,Coney P J.Geologic development of the Cordilleran metamorphic core complexes.Geology,1979,7:120-124
[40]Davis G H.Shear-zone model for the origin of metamorphic core complexes.Geology,1983,11:342-347
[41]Wernicke B.Low-angle normal faults in the basin and range province:nappe tectonics in an extending orogen.Nature,1981,291:645-648
[42]Xypolias P,Doutsos T.Kinematics of rock flow in a crustal-scale shear zone:implication for the orogenic evolution of southwesten Hellenides.Geological Magazine,2000,137:81-69
[2]Lee J,Miller,E L,Sutter J F.Ductile strain and metamorphism in an extensional tectonic setting:a case study from the northern Snake Range,Nevada,USA//Coward M P,Dewey J F,Hancock P L.Continental extensional tectonics.London:Blackwell Scientific Publication,1987:267-289
[3]Zhang Jinjiang,Zheng Yadong,Liu Shuwen.Application of general shear theory to the study of formation mechanism of the metamorphic core complex:a case study of Xiaoqinling in central China.Acta Geologica Sinica,2000,74:19-28
[4]郑亚东,王涛,王新社.世纪构造地质学与力学的新理论:最大有效力矩准则.自然科学进展,2005,15(2):142-148
[5]王新社,郑亚东,张进江.呼和浩特变质核杂岩伸展运动学特征及剪切作用类型.地质通报,2002,21(4/5):238-243
[6]王新社,张尚坤,张富中.鲁西青邑韧性剪切带运动学涡度及剪切作用类型.地球学报,2005,26(5):423-428
[7]Wang Xinshe,Zheng Yadong,Wang Tao.Strain and shear types of the Louzidian ductile shear zone in southern Chifeng,Inner Mongolia China.Science in China:Ser D,2007,37(2):160-166
[8]Li Jianbo,Wang Tao,Ouyang Zixia.Strain and kinematic vorticity analysis of the Louzidian lowangle ductile detachment zone in Chifeng,Inner Mongolia,China.Science in China:Ser D,2010,53(11):1611-1624
[9]Li Jianbo,Wang Tao,Guo Lei,et al.Strain,kinematic vorticity and ductile thinning along the detachment zone of the Yunmeng Shan metamorphic core complex,Beijing,China.Acta Geologica Sinica,2013,87(4):989-1004
[10]李建波,鲁勇花,蒋振频.辽南万福变质核杂岩的应变与剪切作用类型.东华理工大学学报:自然科学版,2012,35(3):238-245
[11]许志琴,李海兵,王宗秀.辽南地壳的收缩作用及伸展作用.地质论评,1991,37(3):193-202
[12]洪作民,黄镇福,刘效良,等.辽东半岛南部前寒武系地质.北京:地质出版社,1991
[13]杨中柱,孟庆成,江江,等.辽南变质核杂岩构造.辽宁地质,1996(4):241-250
[14]郭春丽,吴福元,杨进辉,等.中国东部早白垩世岩浆作用的伸展构造性质:以辽东半岛南部饮马湾山岩体为例.岩石学报,2004,20(5):1193-1203
[15]Yang Jinghui,Wu Fuyuan,Chung Sunlin,et al.Rapid exhumation and cooling of the Liaonan metamorphic core complex:inferences from 40Ar-39Ar thermochronology and implications for Late Mesozoic extension in the eastern North China Craton.Geological Society of America,2007,119:1405-1414
[16]欧阳志侠,王涛,李建波.辽南金州拆离带糜棱状花岗岩脉体变形特征及锆石SHRIMP U-Pb年龄韧性拆离时限的新证据.岩石矿物学杂志,2010,29(4):403-413
[17]Liu Junlai,Davis G A,Lin Zhiyong,et al.The Liaonan metamorphic core complex,Southeastern Liaoning Province,North China:a likely contributor to Cretaceous rotation of Eastern Liaoning,Korea and contiguous areas.Tectonophysics,2005,407:65-80
[18]纪沫,刘俊来,胡玲.辽南变质核杂岩饮马湾山和赵房岩体锆石SHRIMP U-Pb年龄及其地质意义.岩石学报,2009,25(1):173-181
[19]曾令森,李海兵.辽南金州隆起区构造变形与流体作用.高校地质学报,1996,2(2):155-165
[20]郑亚东,曾令森,李建波,等.辽南中生代造山作用与晚造山伸展垮塌作用.地质科学,2009,44(3):811-824
[21]Lister G S,Davis G A.The origin of metamorphic core complexes and detachment faults formed during Tertiary continental extension in the northern Colorado River region,USA.Journal of Structural Geology,1989,11(1):65-94
[22]De Paor D G.Rf/φf strain analysis using an orientation net.Journal of Structural Geology,1988,10(4):323-333
[23]Simpson C,de Paor D G.Strain and kinematic analysis in general shear zones.Journal of Structural Geology,1993,15(1):1-20
[24]张进江,郑亚东.运动学涡度、极摩尔圆及其在一般剪切带定量分析中的应用.地质力学学报,1995,1(3):56-64
[25]张进江,郑亚东.运动学涡度和极摩尔圆的基本原理与应用.地质科技情报,1997,16(3):33-39
[26]Zhang Jinjiang,Zheng Yadong.Polar Mohr constructions of strain analysis in general shear zone.Journal of Structural Geology,1997,19(5):745-748
[27]郑亚东,王涛,张进江.运动学涡度的理论与实践.地学前缘,2008,15(3):209-220
[28]郑亚东,王涛,王新社.世纪构造地质学与力学的新理论:最大有效力矩准则.自然科学进展,2005,15(2):142-148
[29]郑亚东,王涛,王新社.最大有效力矩准则及相关地质构造.地学前缘,2007,14(4):49-60
[30]郑亚东,王涛,王新社.最大有效力矩准则的理论与实践.北京大学学报:自然科学版,2007,43(3):145-156
[31]郑亚东,王涛,王新社.神秘的109.4°:共轭变形带的夹角.地质科学,2007,42(1):1-9
[32]郑亚东,王涛,张进江.运动学涡度的理论与实践.地学前缘,2008,15(3):209-220
[33]Wallis S R,Platt J P,Knott S D.Recognition of sunconvergence extension in accretionary wedges with examples from the Calabrian Arc and the Eastern Alps.American Journal of Science,1993,293:463-495
[34]Tikoff B,Teyssier C.Strain modeling of displacement-field partitioning in transpressional orogens.Journal of Structural Geology,1994,16(11):1575-1588
[35]Coney P J,Harms T A.Cordilleran metamorphic core complexes:Cenozoic extensional relics of Mesozoic compression.Geology,1984,12:550-554
[36]Sonder L J,England P C,Wernicke B P.A physical model for Cenozoic extension of western North America//Coward M P,Dewey J F,Hancock P L.Continental extensional tectonics.Geological Society of London Special Publication,1987,28:187-201
[37]Dewey J F.Extensional collapse of orogens.Tectonics,1988,7:1123-1139
[38]吴福元,杨进辉,张艳斌,等.辽西东南部中生代花岗岩时代.岩石学报,2006,22(2):315-325
[39]Davis G H,Coney P J.Geologic development of the Cordilleran metamorphic core complexes.Geology,1979,7:120-124
[40]Davis G H.Shear-zone model for the origin of metamorphic core complexes.Geology,1983,11:342-347
[41]Wernicke B.Low-angle normal faults in the basin and range province:nappe tectonics in an extending orogen.Nature,1981,291:645-648
[42]Xypolias P,Doutsos T.Kinematics of rock flow in a crustal-scale shear zone:implication for the orogenic evolution of southwesten Hellenides.Geological Magazine,2000,137:81-69