南苏鲁芝麻房石榴石橄榄岩中橄榄石的“C”类组构及其形成条件探讨
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摘要
上地幔地震的各向异性主要归因于橄榄石的优选方位,不同的橄榄石优选方位模式可以作为上地幔不同动力学作用的指示剂。不同应力和含水量条件下的高温变形实验已经确定出五类橄榄石组构模式(“A”型、“B”型、“C”型、“D”型和“E”型)。本文运用电子背散射(EBSD)技术对来自苏鲁超高压变质带南部的芝麻房石榴石橄榄岩的橄榄石进行了优选方位测定,不同变形程度的橄榄石均显示了[100]轴近垂直于面理和[001]轴近平行于线理的特征,为“C”类组构模式,可见组构类型与变形程度没有关系,并且橄榄石组构所显示的NW向SE的剪切指向,与围岩-正、副片麻岩中形成于折返过程的石英优选方位所显示的SE向NW的剪切指向完全不同,说明芝麻房石榴石橄榄岩中橄榄石的“C”类组构是折返前形成的。结合橄榄石结构水的测量和已有的芝麻房石榴石橄榄岩形成的温压条件,推测该组构形成于含水俯冲带中,认为芝麻房石榴石橄榄岩的原岩来自于高含水的上部地幔楔碎块,与俯冲的陆壳物质一起经历了超高压变质作用并最终折返至地表。
Upper mantle seismic anisotropy is mainly attributed to the lattice-preferred orientation ( LPO) of olivine, which is regarded as an indicator of different dynamic processes. Five types of olivine fabric have been identified for olivine aggregates in simple shear deformation experiments under various water contents and stresses. Using the electron backscatter diffraction (EBSD) technique, we measured the LPOs of olivine porphyroclasts in the Zhimafang garnet peridotite of the southern Sulu ultrahigh-pressure metamorphic terrane. Although these olivine grains have experienced different degrees of deformation, all of them have distinctive type-C fabric in which [100] axes is concentrated subnormal to the foliation and [001] axes subparallel to the lineation. Our data do not show any correlation between the types of olivine fabric and degrees of deformation. This observation together with the differences in the shear direction inferred from olivine fabric from that from quartz fabricformed during exhumation demonstrate that the type-C olivine fabric did not result from deformation associated with the exhumation phases of the Sulu UHP rocks. In stead, the type-C olivine fabric was formed in a subduction zone under high water activity, as suggested by water contents of olivine crystals and the temperature and pressure conditions of the Zhimafang garnet peridotite. These results suggest that during subduction of the Yangtze plate, the Zhimafang garnet peridotite was captured from the overlying mantle wedge and then experienced ultrahigh-pressure metamorphism as the Yangtze continental block was subducted to mantle depths.
Upper mantle seismic anisotropy is mainly attributed to the lattice-preferred orientation ( LPO) of olivine, which is regarded as an indicator of different dynamic processes. Five types of olivine fabric have been identified for olivine aggregates in simple shear deformation experiments under various water contents and stresses. Using the electron backscatter diffraction (EBSD) technique, we measured the LPOs of olivine porphyroclasts in the Zhimafang garnet peridotite of the southern Sulu ultrahigh-pressure metamorphic terrane. Although these olivine grains have experienced different degrees of deformation, all of them have distinctive type-C fabric in which [100] axes is concentrated subnormal to the foliation and [001] axes subparallel to the lineation. Our data do not show any correlation between the types of olivine fabric and degrees of deformation. This observation together with the differences in the shear direction inferred from olivine fabric from that from quartz fabricformed during exhumation demonstrate that the type-C olivine fabric did not result from deformation associated with the exhumation phases of the Sulu UHP rocks. In stead, the type-C olivine fabric was formed in a subduction zone under high water activity, as suggested by water contents of olivine crystals and the temperature and pressure conditions of the Zhimafang garnet peridotite. These results suggest that during subduction of the Yangtze plate, the Zhimafang garnet peridotite was captured from the overlying mantle wedge and then experienced ultrahigh-pressure metamorphism as the Yangtze continental block was subducted to mantle depths.
引文
Bell DR, Rossman GR, Maldener J, Endisch D, and Rauch F. 2003. Hydroxide in olivine: A quantitative determination of the absolute amount and calibration of the IR spectrum. Journal of Geophysical Research, 108, B2, 2105, doi: 10.1029/2001JB000679.
Ben Ismail W, Mainprice D. 1998. An olivine fabric database: an overview of upper mantle fabrics and seismic anisotropy. Tectonophysics, 269:145-157
Boullier AM, Nicolas A. 1975. Classification of textures and fabrics of peridotite xenoliths from South African kimberlites. Physics and Chemistry of the Earth, 9:467-475
Bystrick M, Kunze K, Burlini L, Burg J-P. 2000. High shear strain of olivine aggregates: rheological and seismic consequences. Science, 290: 1564-1567
Christensen NI. 1984. The magnitude, symmtry and origin of upper mantle anisotropy based on fabric analysis of ultramafic tectonics. Geophysical Journal of the Royal Astronomical Society, 76: 89-111
Den Tex E. 1969. Origin of ultramafic rocks, their tectonic setting and history: a contribution to the discussing of the paper " The origin of ultramafic and ultrabasic rocks'by P. J. Wyllie. Tectonophysies, 7: 457-488
Frese K, Trommsdorf V, Kunze K. 2003. Olivine [100] normal to foliation: lattice preferred orientation in progade garnet peridotite formed at high H2O activity, Cima di Gagnone ( Central Apls). Contribution to Mineralogy and Petrology, 145 : 73-86
Ji SC, Zhao X, Francis D. 1994. Calibration of shear-wave splitting in the subcontinental upper mantle beneath active orogenic belts using ultramafic xenoliths from the Canadian Cordillera and Alaska. Tectonophysics, 239: 1-27
Jung H, Karato S. 2001. Water-induced fabric transitions in olivine. Science, 293: 1460-1463
Katayama I, Jung H, Karato S. 2004. New type of olivine fabric from deformation experiments at modest water content and low stress. Geology, 32: 1045-1048
Li TF, Yang JS, Zhang RY. 2003. Peridotite from the pre-pilot hole ( PP1) of the Chinese Continental Scientific Drilling Project and its bearing on depleted and metasomatic upper mantle. Acta Geologica Sinica, 77: 492-509 (in Chinese with English abstract).
Littlejohn AL, Greenwood HJ. 1974. Lherzolite nodules in basalts from British Columbia, Canada. Canadian Journal of Earth Sciences ,11: 1288-1308
Liu FL, Xu ZQ, Katayama I, Yang JS, Maruyama Sh. , Liou JG. 2001. Mineral inclusions in Zircons of para-and orthogneiss from pre-pilot drillhole CCSD-PP1 , Chinese Continental Scientific Drilling project. Lithos, 59:199-215
Mehl L, Hacker BR, Hirth G. 2003. Arc-parallel flow within the mantle wedge: evidence from the accreted Talkeenta arc, south central Alaska. Journal of Geophysical Research, 108, B8, 2375, 10. 1029/2002JB002233
Mercier J-CC. 1985. Olivine and pyroxenes. In: Wenk, H.-R. (Ed.), Preferred Orientation in Deformed Metals and Rocks: An Introduction to Modern Texture Analysis. Academic Press. 407- 430
Mercier J-CC, Nicolas A. 1975. Textures and fabrics of upper-mantle peridotites as illustrated by xenoliths from basalts. Journal of Petrology, 16:454-487
Mizukami T, Wallis SR, Yamamoto J. 2004. Natural examples of olivine lattice preferred orientation patterns with a flow-normal a-axis maximum. Nature, 427: 432-436
Mockel JR. 1969. Structural petrology of the garnet peridotite of Aple Arami (Ticino, Switzerland). Leidse Geol. Med. , 42: 61-130
Nicolas A, Christensen NI. 1987. Formation of anisotropy in upper mantle peridotites a review. In: Fuchs, K. , and Froideoaux, C. ( eds.), Composition, structure and dynamics of the lithosphere- asthenosphere system. Trans. ed. Washington, D. C. : AGU, 16: 407-433
Nimis P, Trommsdorff V. 2001. Revised thermobarometry of Alpe Arami and other garnet peridotites from the central Alps. Journal of Petrology, 42: 103-115
Park J, Levin V. 2002. Seismic anisotropy: tracing plate dynamics in the mantle. Science, 296: 485-489
Paterson MS. 1982. The determination of hydroxyl by infrared absorption in quartz silicate glasses and similar materials. Bulletin of Materials, 105:20-29
Sawaguchi T. 2004. Deformation history and exhumation process of the Horoman peridotite complex, Hokkaido, Japan. Tectonophysics, 379:109-126
Xu ZQ, Chen J, Yang JS, Li XP, Chen FY. 2003a. Discovery of titanoclinohumite and titanochondrodite exsolution in clinopyroxene included in garnet peridotite and their significance. Acta Geologica Sinica, 77: 549-555 (in Chinese with English abstract).
Xu ZQ, Zhang ZM, Liu FL, Yang JS, Li HB, Yang TN, Qiu HJ, Li TF, MengFC, Cheng SZ, Tang ZM, Chen FY. 2003b. Exhumation structure and mechanism of the Sulu ultrahigh-pressure metamorphic belt, central China. Acta Geologica Sinica, 77: 433-450 (in Chinese with English abstract).
Yang JJ, Jahn B-M. 2000. Deep subduction of mantle-derived garnet peridotites from the Su-Lu UHP metamorphic terrane in China. Journal of Metamorphic Geology, 18:167-180
Yang JJ, Godard G, Kienast JR, Lu Y, Sun J. 1993. Ultrahigh-pressure magnesite-bearing garnet peridotites from northeastern Jiangsu, China. Journal of Geology, 101:541-554
Yang JS, Xu ZQ, Wu CL, Liu FL, Shi RD, Wooden J, Maruyama S. 2002. SHRIMP U-Pb dating on coesite-bearing zircon: evidence for Indosinian ultrahigh-pressure metamorphism in Su-Lu, east China. Acta Geologica Sinica, 76: 354-372 (in Chinese with English abstract).
Zhang RY, Liou JG. 1998. Dual origin of garnet peridotites of Dabie- Sulu UHP terrane, eastern-central China. Episodes, 21 : 229-234
Zhang RY, Liou JG, Yang JS, Yui TF. 2000. Petrochemical constraints for dual origin of garnet peridotites from the Dabie-Sulu UHP terrane, eastern-central China. Journal of Metamorphic Geology, 18: 149-166
Zhang S, Karato S. 1995. Lattice preferred orientation of olivine aggregates deformed in simple shear. Nature, 375 : 774-777
Zhang S, Karato S, Fitz Gerald J, Faul UH, Zhou Y. 2000. Simple shear deformation of olivine aggregates. Tectonophysics, 316: 133-152
李天福,杨经绥,张儒媛．2003．江苏东海芝麻房预先导孔(CCSD- PPI)橄榄岩及其反映的上地幔亏损和交代事件．地质学报,77 (4):492-509
许志琴,陈晶,杨经绥,李旭平,陈方远．2003a．苏鲁超高压变质带 石榴石橄榄岩中含钛硅镁石出溶体的发现及其意义．地质学 报,77(4):549-555
许志琴,张泽明,刘福来,杨经绥,李海兵,杨天南,邱海峻,李天 福,孟繁聪,陈志忠,唐哲民,陈方远．2003b．苏鲁高压-超高 压变质带的折返构造及折返机制．地质学报,77(4):433—450
杨经绥,许志琴,吴才来,刘福来,史仁灯,J．Wooden,S．Maruyama． 2002．含柯石英锆石的SHRIMP U-Pb定年:胶东印支期超高压 变质岩作用的证据．地质学报,76(3):354—372
Ben Ismail W, Mainprice D. 1998. An olivine fabric database: an overview of upper mantle fabrics and seismic anisotropy. Tectonophysics, 269:145-157
Boullier AM, Nicolas A. 1975. Classification of textures and fabrics of peridotite xenoliths from South African kimberlites. Physics and Chemistry of the Earth, 9:467-475
Bystrick M, Kunze K, Burlini L, Burg J-P. 2000. High shear strain of olivine aggregates: rheological and seismic consequences. Science, 290: 1564-1567
Christensen NI. 1984. The magnitude, symmtry and origin of upper mantle anisotropy based on fabric analysis of ultramafic tectonics. Geophysical Journal of the Royal Astronomical Society, 76: 89-111
Den Tex E. 1969. Origin of ultramafic rocks, their tectonic setting and history: a contribution to the discussing of the paper " The origin of ultramafic and ultrabasic rocks'by P. J. Wyllie. Tectonophysies, 7: 457-488
Frese K, Trommsdorf V, Kunze K. 2003. Olivine [100] normal to foliation: lattice preferred orientation in progade garnet peridotite formed at high H2O activity, Cima di Gagnone ( Central Apls). Contribution to Mineralogy and Petrology, 145 : 73-86
Ji SC, Zhao X, Francis D. 1994. Calibration of shear-wave splitting in the subcontinental upper mantle beneath active orogenic belts using ultramafic xenoliths from the Canadian Cordillera and Alaska. Tectonophysics, 239: 1-27
Jung H, Karato S. 2001. Water-induced fabric transitions in olivine. Science, 293: 1460-1463
Katayama I, Jung H, Karato S. 2004. New type of olivine fabric from deformation experiments at modest water content and low stress. Geology, 32: 1045-1048
Li TF, Yang JS, Zhang RY. 2003. Peridotite from the pre-pilot hole ( PP1) of the Chinese Continental Scientific Drilling Project and its bearing on depleted and metasomatic upper mantle. Acta Geologica Sinica, 77: 492-509 (in Chinese with English abstract).
Littlejohn AL, Greenwood HJ. 1974. Lherzolite nodules in basalts from British Columbia, Canada. Canadian Journal of Earth Sciences ,11: 1288-1308
Liu FL, Xu ZQ, Katayama I, Yang JS, Maruyama Sh. , Liou JG. 2001. Mineral inclusions in Zircons of para-and orthogneiss from pre-pilot drillhole CCSD-PP1 , Chinese Continental Scientific Drilling project. Lithos, 59:199-215
Mehl L, Hacker BR, Hirth G. 2003. Arc-parallel flow within the mantle wedge: evidence from the accreted Talkeenta arc, south central Alaska. Journal of Geophysical Research, 108, B8, 2375, 10. 1029/2002JB002233
Mercier J-CC. 1985. Olivine and pyroxenes. In: Wenk, H.-R. (Ed.), Preferred Orientation in Deformed Metals and Rocks: An Introduction to Modern Texture Analysis. Academic Press. 407- 430
Mercier J-CC, Nicolas A. 1975. Textures and fabrics of upper-mantle peridotites as illustrated by xenoliths from basalts. Journal of Petrology, 16:454-487
Mizukami T, Wallis SR, Yamamoto J. 2004. Natural examples of olivine lattice preferred orientation patterns with a flow-normal a-axis maximum. Nature, 427: 432-436
Mockel JR. 1969. Structural petrology of the garnet peridotite of Aple Arami (Ticino, Switzerland). Leidse Geol. Med. , 42: 61-130
Nicolas A, Christensen NI. 1987. Formation of anisotropy in upper mantle peridotites a review. In: Fuchs, K. , and Froideoaux, C. ( eds.), Composition, structure and dynamics of the lithosphere- asthenosphere system. Trans. ed. Washington, D. C. : AGU, 16: 407-433
Nimis P, Trommsdorff V. 2001. Revised thermobarometry of Alpe Arami and other garnet peridotites from the central Alps. Journal of Petrology, 42: 103-115
Park J, Levin V. 2002. Seismic anisotropy: tracing plate dynamics in the mantle. Science, 296: 485-489
Paterson MS. 1982. The determination of hydroxyl by infrared absorption in quartz silicate glasses and similar materials. Bulletin of Materials, 105:20-29
Sawaguchi T. 2004. Deformation history and exhumation process of the Horoman peridotite complex, Hokkaido, Japan. Tectonophysics, 379:109-126
Xu ZQ, Chen J, Yang JS, Li XP, Chen FY. 2003a. Discovery of titanoclinohumite and titanochondrodite exsolution in clinopyroxene included in garnet peridotite and their significance. Acta Geologica Sinica, 77: 549-555 (in Chinese with English abstract).
Xu ZQ, Zhang ZM, Liu FL, Yang JS, Li HB, Yang TN, Qiu HJ, Li TF, MengFC, Cheng SZ, Tang ZM, Chen FY. 2003b. Exhumation structure and mechanism of the Sulu ultrahigh-pressure metamorphic belt, central China. Acta Geologica Sinica, 77: 433-450 (in Chinese with English abstract).
Yang JJ, Jahn B-M. 2000. Deep subduction of mantle-derived garnet peridotites from the Su-Lu UHP metamorphic terrane in China. Journal of Metamorphic Geology, 18:167-180
Yang JJ, Godard G, Kienast JR, Lu Y, Sun J. 1993. Ultrahigh-pressure magnesite-bearing garnet peridotites from northeastern Jiangsu, China. Journal of Geology, 101:541-554
Yang JS, Xu ZQ, Wu CL, Liu FL, Shi RD, Wooden J, Maruyama S. 2002. SHRIMP U-Pb dating on coesite-bearing zircon: evidence for Indosinian ultrahigh-pressure metamorphism in Su-Lu, east China. Acta Geologica Sinica, 76: 354-372 (in Chinese with English abstract).
Zhang RY, Liou JG. 1998. Dual origin of garnet peridotites of Dabie- Sulu UHP terrane, eastern-central China. Episodes, 21 : 229-234
Zhang RY, Liou JG, Yang JS, Yui TF. 2000. Petrochemical constraints for dual origin of garnet peridotites from the Dabie-Sulu UHP terrane, eastern-central China. Journal of Metamorphic Geology, 18: 149-166
Zhang S, Karato S. 1995. Lattice preferred orientation of olivine aggregates deformed in simple shear. Nature, 375 : 774-777
Zhang S, Karato S, Fitz Gerald J, Faul UH, Zhou Y. 2000. Simple shear deformation of olivine aggregates. Tectonophysics, 316: 133-152
李天福,杨经绥,张儒媛．2003．江苏东海芝麻房预先导孔(CCSD- PPI)橄榄岩及其反映的上地幔亏损和交代事件．地质学报,77 (4):492-509
许志琴,陈晶,杨经绥,李旭平,陈方远．2003a．苏鲁超高压变质带 石榴石橄榄岩中含钛硅镁石出溶体的发现及其意义．地质学 报,77(4):549-555
许志琴,张泽明,刘福来,杨经绥,李海兵,杨天南,邱海峻,李天 福,孟繁聪,陈志忠,唐哲民,陈方远．2003b．苏鲁高压-超高 压变质带的折返构造及折返机制．地质学报,77(4):433—450
杨经绥,许志琴,吴才来,刘福来,史仁灯,J．Wooden,S．Maruyama． 2002．含柯石英锆石的SHRIMP U-Pb定年:胶东印支期超高压 变质岩作用的证据．地质学报,76(3):354—372
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