辽西地区台里韧性剪切带中长英质脉体的变形演化机制研究
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摘要
华北克拉通构造演化及破坏机制一直是地学界的热点话题,中生代华北克拉通东部主要受扬子板块的俯冲使区域内岩浆-变质事件频繁,形成一系列近EW向构造,包括位于辽西地区的一条中生代NEE向台里韧性剪切带。该韧性剪切带中发育有S-C组构、旋转碎斑、石香肠、长英质脉体等丰富的构造现象。通过野外观测和室内综合分析,识别出其中长英质脉体的演化序列为"分异脉→香肠化→透镜化→碎斑化→细粒化→丝带化"六个变形阶段。对各变形阶段样品切制垂直面理平行线理的薄片,并对薄片基质层进行二维有限应变测量分析与统计,包括真应变差(ε_1-ε_2)等值线图、岩层厚度比(S)等值线图、运动学涡度(W_k)等值线图。其中W_k在演化前期主要小于0.71,演化中期主要大于0.71,演化后期主要小于0.71,表明长英质脉体演化过程前期主要为纯剪切作用,中期为简单剪切作用,后期为纯剪切作用,同时W_k为正值和S小于1反映研究区内韧性剪切带在伸展减薄的动力学背景下形成,这对了解华北克拉通东部中生代构造演化提供了新的约束。
The tectonic evolution and the destruction of the North China Craton are matters of debate. The subduction of the Yangtze plate during Mesozoic induced extensive magmatic and metamorphic events in the western North China Craton, which formed a series of nearly EW-trending tectonic features, including the Mesozoic NEE-trending Taili ductile shear zone in the western part of the Liaoning province. We identified many structural features within this ductile shear zone, such as S-C fabric, rotational porphyroclast, boudinages, felsic veins, etc. Field investigation and laboratory analyses revealed a 6-stage's evolution of the felsic veins, which can be classified as "fractionation veins→boudinages→lenticel→porphyroclast→fine-grain→silk ribbon". Thin sections perpendicular to the foliation and parallel to the lineation were prepared for samples taken from each of the evolutionary stages. Two-dimensional finite strain measurements and statistics were performed for matrix in the thin sections, including true differential strain(ε_1-ε_2), stratum thickness ratio(S), and kinematic vorticity(W_k) contour map. The kinematic vorticity(W_k) for the early stage samples is generally less than 0.71, it is greater than 0.71 for the middle stage samples, and less than 0.71 for the late stage samples, suggesting that both the early-and late-stage deformations of the felsic veins were mainly pure shear, the middle-stage deformation was mainly simple shear. Moreover, the positive value of the kinematic vorticity(W_k) and the less than 1 stratum thickness ratio indicate that the Taili ductile shear zone was formed under an extensional tectonic background triggered by the lithosphere thinning. This study offers new constraints on the Mesozoic tectonic evolution of the North China Craton.
The tectonic evolution and the destruction of the North China Craton are matters of debate. The subduction of the Yangtze plate during Mesozoic induced extensive magmatic and metamorphic events in the western North China Craton, which formed a series of nearly EW-trending tectonic features, including the Mesozoic NEE-trending Taili ductile shear zone in the western part of the Liaoning province. We identified many structural features within this ductile shear zone, such as S-C fabric, rotational porphyroclast, boudinages, felsic veins, etc. Field investigation and laboratory analyses revealed a 6-stage's evolution of the felsic veins, which can be classified as "fractionation veins→boudinages→lenticel→porphyroclast→fine-grain→silk ribbon". Thin sections perpendicular to the foliation and parallel to the lineation were prepared for samples taken from each of the evolutionary stages. Two-dimensional finite strain measurements and statistics were performed for matrix in the thin sections, including true differential strain(ε_1-ε_2), stratum thickness ratio(S), and kinematic vorticity(W_k) contour map. The kinematic vorticity(W_k) for the early stage samples is generally less than 0.71, it is greater than 0.71 for the middle stage samples, and less than 0.71 for the late stage samples, suggesting that both the early-and late-stage deformations of the felsic veins were mainly pure shear, the middle-stage deformation was mainly simple shear. Moreover, the positive value of the kinematic vorticity(W_k) and the less than 1 stratum thickness ratio indicate that the Taili ductile shear zone was formed under an extensional tectonic background triggered by the lithosphere thinning. This study offers new constraints on the Mesozoic tectonic evolution of the North China Craton.
引文
陈虹,胡健民,武国利.2009.韧性剪切带糜棱岩中不对称旋转碎斑系剪切指向模拟实验研究现状及其问题.地质通报,28(4):439-455.
高山,章军锋,许文良,刘勇胜.2009.拆沉作用与华北克拉通破坏.科学通报,54(14):1962-1973.
胡玲,刘俊来,纪沫,曹淑云,张宏远,赵中岩.2009.变形显微构造识别手册.北京:地质出版社:1-96.
黄汲清,任纪舜,姜春发,张正坤,秦德余.1980.中国大地构造及其演化.北京:科学出版社:64.
李刚,刘正宏,刘俊来,李永飞,徐仲元,董晓杰.2012.医巫闾山伸展型韧性剪切带的形成过程及年代学证据.中国科学:地球科学,42(6):879-892.
李健,张霞,金巍,郑培玺.2013.辽西台里地区斑状花岗质片麻岩特征及其地质意义.高校地质学报,19(2):259-273.
李云安.1993.岩石有限应变测量的莫尔圆图解网法.地质科技情报,12(1):53-58.
李志勇,曾佐勋.2006.利用惯量椭圆进行岩石有限应变分析.地质科技情报,25(6):37-40.
李忠,董仁国,郑建平.2007.华北克拉通东部南北缘中生代火山沉积格局及其构造转折过程.古地理学报,9(3):227-242.
林舸,赵崇斌,肖焕钦,陈广浩,闫义,张德圣,刘士林,陈运平.2008.华北克拉通构造活化的动力学机制与模型.大地构造与成矿学,32(2):133-142.
林伟,王军,刘飞,冀文斌,王清晨.2013.华北克拉通及邻区晚中生代伸展构造及其动力学背景的讨论.岩石学报,29(5):1791-1810.
林晓辉,秦正永.2003.对燕山辽西地区构造格局的认识和讨论.化工矿产地质,25(1):5-12.
刘红涛,孙世华,刘建明,翟明国.2002.华北克拉通北缘中生代高锶花岗岩类:地球化学与源区性质.岩石学报,18(3):257-274.
罗威,刘永江,方博文,李伟民,纪秋梅,梁国宇.2014.辽西台里韧性剪切带糜棱岩中眼球状构造的成因分析.世界地质,33(4):844-854.
王根厚,张长厚,王果胜,吴正文.2001.辽西地区中生代构造格局及其形成演化.现代地质,15(1):1-7.
王涛,郑亚东,张进江,王新社,曾令森,童英.2007.华北克拉通中生代伸展构造研究的几个问题及其在岩石圈减薄研究中的意义.地质通报,26(9):1154-1166.
吴福元,徐义刚,高山,郑建平.2008.华北岩石圈减薄与克拉通破坏研究的主要学术争论.岩石学报,24(6):3-32.
吴林波,曾佐勋,高曦,王杰.2012.鄂东南铁山梯形石香肠构造基质层中的应变测量与分析.现代地质,26(2):294-307.
徐珏,陈振宇,陈毓川,王登红,李纯杰,余金杰,王平安.2006.大陆科学钻探工程CCSD主孔中发现的大量流体交代脉体.地球科学,31(4):551-556.
许文良,王清海,王冬艳,裴福萍,高山.2004.华北克拉通东部中生代岩石圈减薄的过程与机制:中生代火成岩和深源捕虏体证据.地学前缘,11(3):309-317.
杨志强,黄永锋,李文智.2012.新疆东戈壁斑岩型钼矿床脉体特征.中国钼业,36(3):18-27.
喻磊,周新,李江力,何海林.2013.混合岩脉体中的石榴石及其地质意义.科技资讯,(7):240-241.
曾佐勋,樊春,刘立林,陈桂华,凌峰,彭振华.1999.构造流变计.地质科技情报,18(4):14-18.
曾佐勋,付永涛,李艳霞.1997.北京西山膨缩石香肠流变性质构造研究初探.地质力学学报,3(1):45-49.
曾佐勋,刘立林.1992.构造模拟.武汉:中国地质大学出版社:50-100.
翟明国,彭澎.2007.华北克拉通古元古代构造事件.岩石学报,23(11):3-20.
张进江,郑亚东.1995.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,1(3):55-64.
赵宗溥.1963.中国东部的燕山运动.地质科学,3(3):128-138.
郑培玺,金巍,周燕,李建,郑长青.2009.辽西地区台子里花岗质片麻岩锆石U-Pb年龄及其地质意义.吉林大学学报(地球科学版),39(3):455-460.
郑亚东,王涛,张进江.2008.运动学涡度的理论与实践.地学前缘,15(3):209-220.
朱日祥,郑天愉.2009.华北克拉通破坏机制与古元古代板块构造体系.科学通报,54(14):1950-1961.
Bose S and Marques F O.2004.Controls on the geometry of tails around rigid circular inclusions:Insights from analogue modelling in simple shear.Journal of Structural Geology,26:2145-2156.
Driessche J V D and Brun J P.1987.Rolling structures at large shear strain.Journal of Structural Geology,9(5-6):691-704,IN9-IN10.
Jessup M J,Law R D and Frassi C.2007.The Rigid Grain Net(RGN):An alternative method for estimating mean kinematic vorticity number(Wm).Journal of Structural Geology,29:411-421.
Kusky T M,Windley B F and Zhai M.2007.Tectonic evolution of the North China Block:From orogen to craton to orogen.Geological Society,London,Special Publications,280:1-34.
Li S Z,Kusky T M,Zhao G,Wu F,Liu J,Sun M and Wang L.2007.Mesozoic tectonics in the Eastern Block of the North China Craton:Implications for subduction of the Pacific plate beneath the Eurasian plate.Geological Society,London,Special Publications,280:171-188.
Liang C,Liu Y,Neubauer F,Bernroider M,Jin W,Li W,Zeng Z,Wen Q and Zhao Y.2015.Structures,kinematic analysis,rheological parameters and temperature-pressure estimate of the Mesozoic Xingcheng-Taili ductile shear zone in the North China Craton.Journal of Structural Geology,78:27-51.
Lloyd G E,Ferguson C C and Reading K.1982.Astress-transfer model for the development of extension fracture boudinage.Journal of Structural Geology,4:355-372.
Mandal N,Dhar R,Misra S and Chakraborty C.2007.Use of boudinaged rigid objects as a strain gauge:Insights from analogue and numerical models.Journal of Structural Geology,29:759-773.
Marques F O and Coelho S.2001.Rotation of rigid elliptical cylinders in viscous simple shear flow:Analogue experiments.Journal of Structural Geology,23:609-617.
Means W D,Hobbs B E,Lister G S and Williams P F.1980.Vorticity and non-coaxility in progressive deformation.Journal of Structural Geology,2:371-378.
Mulchrone K F and Choudhury K R.2004.Fitting an ellipse to an arbitrary shape:Implications for strain analysis.Journal of structural Geology,26:143-153.
Mulchrone K F and Walsh K.2006.The motion of a non-rigid ellipse in a general 2D deformation.Journal of Structural Geology,28:392-407.
Passchier C W.1988.Analysis of deformation paths in shear zones.Geologische Rundschau,77:309-318.
Peters M,Berger A,Herwegh M and Regenauer-Lieb K.2016.Strain localization in ductile rocks:A comparison of natural and simulated pinch-and-swell structures.Tectonophysics,680:140-154.
Smith R B.1975.Unified theory of the onset of folding,boudinage and mullion structure.Geological Society of America Bulletin,86:1601-1609.
Xypolias P and Koukouvelas I K.2001.Kinematic vorticity and strain rate patterns associated with ductile extrusion in the Chelmos Shear Zone(External Hellenides,Greece).Tectonophysics,338:59-77.
Zhang J and Zheng Y.1997.Polar Mohr constructions for strain analysis in general shear zones.Journal of Structural Geology,19:745-748.
高山,章军锋,许文良,刘勇胜.2009.拆沉作用与华北克拉通破坏.科学通报,54(14):1962-1973.
胡玲,刘俊来,纪沫,曹淑云,张宏远,赵中岩.2009.变形显微构造识别手册.北京:地质出版社:1-96.
黄汲清,任纪舜,姜春发,张正坤,秦德余.1980.中国大地构造及其演化.北京:科学出版社:64.
李刚,刘正宏,刘俊来,李永飞,徐仲元,董晓杰.2012.医巫闾山伸展型韧性剪切带的形成过程及年代学证据.中国科学:地球科学,42(6):879-892.
李健,张霞,金巍,郑培玺.2013.辽西台里地区斑状花岗质片麻岩特征及其地质意义.高校地质学报,19(2):259-273.
李云安.1993.岩石有限应变测量的莫尔圆图解网法.地质科技情报,12(1):53-58.
李志勇,曾佐勋.2006.利用惯量椭圆进行岩石有限应变分析.地质科技情报,25(6):37-40.
李忠,董仁国,郑建平.2007.华北克拉通东部南北缘中生代火山沉积格局及其构造转折过程.古地理学报,9(3):227-242.
林舸,赵崇斌,肖焕钦,陈广浩,闫义,张德圣,刘士林,陈运平.2008.华北克拉通构造活化的动力学机制与模型.大地构造与成矿学,32(2):133-142.
林伟,王军,刘飞,冀文斌,王清晨.2013.华北克拉通及邻区晚中生代伸展构造及其动力学背景的讨论.岩石学报,29(5):1791-1810.
林晓辉,秦正永.2003.对燕山辽西地区构造格局的认识和讨论.化工矿产地质,25(1):5-12.
刘红涛,孙世华,刘建明,翟明国.2002.华北克拉通北缘中生代高锶花岗岩类:地球化学与源区性质.岩石学报,18(3):257-274.
罗威,刘永江,方博文,李伟民,纪秋梅,梁国宇.2014.辽西台里韧性剪切带糜棱岩中眼球状构造的成因分析.世界地质,33(4):844-854.
王根厚,张长厚,王果胜,吴正文.2001.辽西地区中生代构造格局及其形成演化.现代地质,15(1):1-7.
王涛,郑亚东,张进江,王新社,曾令森,童英.2007.华北克拉通中生代伸展构造研究的几个问题及其在岩石圈减薄研究中的意义.地质通报,26(9):1154-1166.
吴福元,徐义刚,高山,郑建平.2008.华北岩石圈减薄与克拉通破坏研究的主要学术争论.岩石学报,24(6):3-32.
吴林波,曾佐勋,高曦,王杰.2012.鄂东南铁山梯形石香肠构造基质层中的应变测量与分析.现代地质,26(2):294-307.
徐珏,陈振宇,陈毓川,王登红,李纯杰,余金杰,王平安.2006.大陆科学钻探工程CCSD主孔中发现的大量流体交代脉体.地球科学,31(4):551-556.
许文良,王清海,王冬艳,裴福萍,高山.2004.华北克拉通东部中生代岩石圈减薄的过程与机制:中生代火成岩和深源捕虏体证据.地学前缘,11(3):309-317.
杨志强,黄永锋,李文智.2012.新疆东戈壁斑岩型钼矿床脉体特征.中国钼业,36(3):18-27.
喻磊,周新,李江力,何海林.2013.混合岩脉体中的石榴石及其地质意义.科技资讯,(7):240-241.
曾佐勋,樊春,刘立林,陈桂华,凌峰,彭振华.1999.构造流变计.地质科技情报,18(4):14-18.
曾佐勋,付永涛,李艳霞.1997.北京西山膨缩石香肠流变性质构造研究初探.地质力学学报,3(1):45-49.
曾佐勋,刘立林.1992.构造模拟.武汉:中国地质大学出版社:50-100.
翟明国,彭澎.2007.华北克拉通古元古代构造事件.岩石学报,23(11):3-20.
张进江,郑亚东.1995.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,1(3):55-64.
赵宗溥.1963.中国东部的燕山运动.地质科学,3(3):128-138.
郑培玺,金巍,周燕,李建,郑长青.2009.辽西地区台子里花岗质片麻岩锆石U-Pb年龄及其地质意义.吉林大学学报(地球科学版),39(3):455-460.
郑亚东,王涛,张进江.2008.运动学涡度的理论与实践.地学前缘,15(3):209-220.
朱日祥,郑天愉.2009.华北克拉通破坏机制与古元古代板块构造体系.科学通报,54(14):1950-1961.
Bose S and Marques F O.2004.Controls on the geometry of tails around rigid circular inclusions:Insights from analogue modelling in simple shear.Journal of Structural Geology,26:2145-2156.
Driessche J V D and Brun J P.1987.Rolling structures at large shear strain.Journal of Structural Geology,9(5-6):691-704,IN9-IN10.
Jessup M J,Law R D and Frassi C.2007.The Rigid Grain Net(RGN):An alternative method for estimating mean kinematic vorticity number(Wm).Journal of Structural Geology,29:411-421.
Kusky T M,Windley B F and Zhai M.2007.Tectonic evolution of the North China Block:From orogen to craton to orogen.Geological Society,London,Special Publications,280:1-34.
Li S Z,Kusky T M,Zhao G,Wu F,Liu J,Sun M and Wang L.2007.Mesozoic tectonics in the Eastern Block of the North China Craton:Implications for subduction of the Pacific plate beneath the Eurasian plate.Geological Society,London,Special Publications,280:171-188.
Liang C,Liu Y,Neubauer F,Bernroider M,Jin W,Li W,Zeng Z,Wen Q and Zhao Y.2015.Structures,kinematic analysis,rheological parameters and temperature-pressure estimate of the Mesozoic Xingcheng-Taili ductile shear zone in the North China Craton.Journal of Structural Geology,78:27-51.
Lloyd G E,Ferguson C C and Reading K.1982.Astress-transfer model for the development of extension fracture boudinage.Journal of Structural Geology,4:355-372.
Mandal N,Dhar R,Misra S and Chakraborty C.2007.Use of boudinaged rigid objects as a strain gauge:Insights from analogue and numerical models.Journal of Structural Geology,29:759-773.
Marques F O and Coelho S.2001.Rotation of rigid elliptical cylinders in viscous simple shear flow:Analogue experiments.Journal of Structural Geology,23:609-617.
Means W D,Hobbs B E,Lister G S and Williams P F.1980.Vorticity and non-coaxility in progressive deformation.Journal of Structural Geology,2:371-378.
Mulchrone K F and Choudhury K R.2004.Fitting an ellipse to an arbitrary shape:Implications for strain analysis.Journal of structural Geology,26:143-153.
Mulchrone K F and Walsh K.2006.The motion of a non-rigid ellipse in a general 2D deformation.Journal of Structural Geology,28:392-407.
Passchier C W.1988.Analysis of deformation paths in shear zones.Geologische Rundschau,77:309-318.
Peters M,Berger A,Herwegh M and Regenauer-Lieb K.2016.Strain localization in ductile rocks:A comparison of natural and simulated pinch-and-swell structures.Tectonophysics,680:140-154.
Smith R B.1975.Unified theory of the onset of folding,boudinage and mullion structure.Geological Society of America Bulletin,86:1601-1609.
Xypolias P and Koukouvelas I K.2001.Kinematic vorticity and strain rate patterns associated with ductile extrusion in the Chelmos Shear Zone(External Hellenides,Greece).Tectonophysics,338:59-77.
Zhang J and Zheng Y.1997.Polar Mohr constructions for strain analysis in general shear zones.Journal of Structural Geology,19:745-748.