西秦岭硅岩中动态重结晶石英颗粒的形变过程研究
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摘要
硅质岩广泛发育于造山带内,受到造山带演化过程的反复改造并以微组构信息记录了造山过程的诸多信息。硅质岩动态重结晶形成了具有统计学上的自相似性、标度不变性和特定的分形维数的动态重结晶颗粒,这些颗粒的分形特征可以较好的揭示变质重结晶过程的变质相、变形温度和应变速率等。尝试对西秦岭的厂坝和八方山—二里河地区硅质岩剖面中局部存在动力重结晶的样品微组构的分形研究。结果表明:样品仅能揭示局部小范围的最新一次应力应变信息,难以反映较大区域内的大规模构造变质对应的应力应变信息。
Cherts, widely distributed in the orogens, are altered repeatedly during the evolution of the orogenies and record many microfabric information during the orogeny evolution. The quartz grains, with statistical self-similarity, graduation invariability and certain dimension, origin from the dynamic recrystallization. These fractal characteristics can be used to reveal the metamorphic facies, deformation temperature and strain rate. So, the microfabric characteristics of metamorphosed cherts, in Changba and Bafangshan-Erlihe area of western Qinling, are studied by the fractal geothermometer and strain speedometer. The results show that the samples can only reveal the latest primary stress and strain information in a small area, and it is difficult to reflect the stress and strain information corresponding to large-scale tectonic metamorphism in a large area.
Cherts, widely distributed in the orogens, are altered repeatedly during the evolution of the orogenies and record many microfabric information during the orogeny evolution. The quartz grains, with statistical self-similarity, graduation invariability and certain dimension, origin from the dynamic recrystallization. These fractal characteristics can be used to reveal the metamorphic facies, deformation temperature and strain rate. So, the microfabric characteristics of metamorphosed cherts, in Changba and Bafangshan-Erlihe area of western Qinling, are studied by the fractal geothermometer and strain speedometer. The results show that the samples can only reveal the latest primary stress and strain information in a small area, and it is difficult to reflect the stress and strain information corresponding to large-scale tectonic metamorphism in a large area.
引文
[1] 周永章,付伟,杨志军,等.藏南地区中生代硅质岩的地球化学特征及其成因意义[J].岩石学报,2008,24(3):600-608.
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[3] 李红中,周永章,杨志军,等.西秦岭八方山—二里河Pb-Zn矿区硅质岩的微区成分特征及演化[J].地学前缘,2010,17(4):290-298.
[4] 李红中,周永章,杨志军,等.秦岭造山带西段八方山—二里河地区硅质岩的地球化学特征及其地质意义[J].岩石学报,2009,25(11):3094-3102.
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[7] 王志敬,成秋明.P-A分形模型定量度量糜棱岩变形过程中石英微结构的变化[J].地球科学-中国地质大学学报,2006,31(3):361-365.
[8] 张波,张进江,郭磊.北喜马拉雅穹隆带然巴韧性剪切带石英动态重结晶颗粒的分维几何分析与主要流变参数的估算[J].地质科学,2006,41(1):158-169.
[9] Cheng Q M.The Perimeter-area fractal model and its application to geology[J].Mathematical Geology,1995,27(1):69-82.
[10] Turcotte D L.Implication of chaos,scale-invariance,and fractal statistics in geology[J].Global and Planetary Change,1990,89:301-308.
[11] Mamtani M A.Strain-rate estimation using fractal analysis of quartz grains in naturally deformed rocks[J].Journal Geological Society of India,2010,75:202-209.
[12] Kruhl J H,Nega M,Milla H E.The fractal shape of grain boundary sutures:reality,model and application as a geothermometer(Book of Abstract)[A]// 2nd Int.conf.on fractal and Dynamic Systems in Geosciences[C].Frankfurt:1995.
[13] Koch P S.Rheology and microstructures of experimentally deformed quartz aggregates[D].Los Angeles:Univ.of Calif.,1983.
[14] Hacker B R,Yin A,John M C.Differential stress,strain rate,and temperatures ofmylonitization in the Rocky Mountains,Nevada:Implications for the rate and duration ofuplift[J].Jour.Geophy Res.,1990,95(B6):8569-8580.
[15] Shimizu I.Theories and applicability of grain size piezometers:The role of dynamic recrystallization mechanisms[J].Journal of Structural Geology,2008,30:899-917.
[16] Stipp M,Stunitz H,Heilbronner R,et al.The eastern Tonal fault zone:a “natural laboratory” for crystal plastic deformation of quartz over a temperature range from 250 to 700℃[J].Journal of Structural Geology,2002,24(12):1861-1884.
[2] Murray R W.Chemical criteria to identify the depositional environment of chert:general principles and applications[J].Sedimentary Geology,1994,90(3-4):213-232.
[3] 李红中,周永章,杨志军,等.西秦岭八方山—二里河Pb-Zn矿区硅质岩的微区成分特征及演化[J].地学前缘,2010,17(4):290-298.
[4] 李红中,周永章,杨志军,等.秦岭造山带西段八方山—二里河地区硅质岩的地球化学特征及其地质意义[J].岩石学报,2009,25(11):3094-3102.
[5] Knauth P L,Epstein S.Hydrogen and oxygen isotope ratios in nodular and bedded cherts[J].Geochimica et Cosmochimica Acta,1976,40(9):1095-1108.
[6] 周永章,Edward H C,Jayanta G,等.地质热场中微量元素迁移的方向性和分维结构图像[J].中国科学(B集),1994,24(12):1308-1313.
[7] 王志敬,成秋明.P-A分形模型定量度量糜棱岩变形过程中石英微结构的变化[J].地球科学-中国地质大学学报,2006,31(3):361-365.
[8] 张波,张进江,郭磊.北喜马拉雅穹隆带然巴韧性剪切带石英动态重结晶颗粒的分维几何分析与主要流变参数的估算[J].地质科学,2006,41(1):158-169.
[9] Cheng Q M.The Perimeter-area fractal model and its application to geology[J].Mathematical Geology,1995,27(1):69-82.
[10] Turcotte D L.Implication of chaos,scale-invariance,and fractal statistics in geology[J].Global and Planetary Change,1990,89:301-308.
[11] Mamtani M A.Strain-rate estimation using fractal analysis of quartz grains in naturally deformed rocks[J].Journal Geological Society of India,2010,75:202-209.
[12] Kruhl J H,Nega M,Milla H E.The fractal shape of grain boundary sutures:reality,model and application as a geothermometer(Book of Abstract)[A]// 2nd Int.conf.on fractal and Dynamic Systems in Geosciences[C].Frankfurt:1995.
[13] Koch P S.Rheology and microstructures of experimentally deformed quartz aggregates[D].Los Angeles:Univ.of Calif.,1983.
[14] Hacker B R,Yin A,John M C.Differential stress,strain rate,and temperatures ofmylonitization in the Rocky Mountains,Nevada:Implications for the rate and duration ofuplift[J].Jour.Geophy Res.,1990,95(B6):8569-8580.
[15] Shimizu I.Theories and applicability of grain size piezometers:The role of dynamic recrystallization mechanisms[J].Journal of Structural Geology,2008,30:899-917.
[16] Stipp M,Stunitz H,Heilbronner R,et al.The eastern Tonal fault zone:a “natural laboratory” for crystal plastic deformation of quartz over a temperature range from 250 to 700℃[J].Journal of Structural Geology,2002,24(12):1861-1884.