中部地壳应变局部化：金州拆离断层带石英结晶学组构约束

发布时间：2018-03-22 05:38

本文选题：应变局部化　切入点：拆离断层带　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：辽南变质核杂岩位于华北克拉通东缘辽东半岛南部。下盘在抬升和剥露过程中形成特定的构造岩序列。从上盘至下盘方向,依次发育碎裂岩、角砾岩化糜棱岩、糜棱岩、糜棱岩化片麻岩和片麻岩,最后在变质核杂岩深处出现未变形的深变质岩。该构造岩序列具有局部无序而宏观整体有序的特征。剥露的主拆离断层——金州拆离断层带内岩石保留了中部地壳脆-韧性转换带矿物变形变质特征,是研究大陆中部地壳岩石变形机制及应变局部化的窗口。拆离作用使金州拆离断层带内石英演化出强烈结晶学优选(CPO),研究中利用EBSD技术对石英集合体进行结晶学方位测量。拆离断层构造岩序列内石英集合体发育的CPO具有同一的不对称性,反映了剪切方向为上盘向NWW,这与野外露头细观下的运动学标志体所反映的剪切方向一致。石英c轴组构样式出现从Y极密到不对称单环带再到I型交叉环带的转换,糜棱岩化片麻岩或糜棱岩内发育Y极密或不对称单环带而角砾岩化糜棱岩内则发育I型交叉环带。强烈的Y极密或者不对称的单环带是石英在角闪岩相下启动柱面a滑移或菱面a滑移形成的。岩石抬升至低温绿片岩相使一部分颗粒转而以底面a滑移主导形成Z极密,与先存单环带叠加构成为I型交叉环带。先存的c轴平行于有限应变中间轴Y轴的颗粒低温绿片岩相下仍继续以柱面a滑移为主。颗粒在变形中的流变学强度取决于其特定的结晶学方位以及变形温度。完整的构造岩序列以及组构渐变带的发育客观上反映了由深至浅,温度由高至低拆离断层的局部化效应。这也进一步佐证了辽南变质核杂岩的发育是区域上最晚一次延伸至中下地壳塑性域的变形作用。
[Abstract]:The metamorphic nuclear complex in southern Liaoning is located in the southern part of the Liaodong Peninsula on the eastern margin of North China Craton. During the uplift and exfoliation, a specific sequence of tectonic rocks is formed in the lower plate. From the upper side to the lower side, the cataclastic rocks, breccia mylonite, mylonite are developed in turn. Mylonized gneiss and gneiss, Finally, undeformed deep metamorphic rocks appeared in the depth of metamorphic core complex. The sequence of tectonic rocks is characterized by local disorder and macroscopic order. The exfoliated main detachment fault-Jinzhou detachment fault zone retains the central crust. Characteristics of mineral deformation and metamorphism in brittle-ductile transition zone, It is a window to study the deformation mechanism and strain localization of crustal rocks in the middle part of the continent. The strong crystallization of quartz in the Jinzhou detachment fault zone is caused by the detachment process. In the study, the EBSD technique is used to study the crystallization of quartz aggregates. Azimuth measurement. CPO developed from quartz aggregates in the detachment fault tectonite series has the same asymmetry. The shear direction is the same as that reflected by the kinematic marker of outcrop in the field. The pattern of quartz c-axis fabric changes from Y extreme density to asymmetric single ring belt to I type cross ring band, which is consistent with the shear direction reflected by the kinematic marker of field outcrop. In mylonitic gneiss or mylonite, Y-dense or asymmetric single-ring zone is developed, while in breccia mylonitic mylonite type I cross ring zone is developed. Strong Y-dense or asymmetrical single-ring zone is quartz starting column under amphibolite facies. Surface a slip or rhombohedral a slip is formed. The rock uplifts to low temperature greenschist facies, causing some particles to form Z maximum density dominated by bottom plane a slip. The superposition of the single ring belt with the pre-existing single ring zone is a type I cross ring zone. The low-temperature greenschist facies of the pre-existing c axis parallel to the Y axis of the finite strain intermediate axis continue to be dominated by columnar a slip. The rheological strength of the particles during deformation is obtained. Due to its specific crystallographic orientation and deformation temperature, the complete sequence of tectonic rocks and the development of the fabric progressive zone objectively reflect the depth to the shallow, The localization effect of temperature from high to low fault further proves that the development of metamorphic core complex in southern Liaoning is the latest deformation extending to the plastic domain of the middle and lower crust in the region.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P542;P573

【相似文献】