低级变质沉积岩区压溶作用在褶皱变形中的意义     

杨新岳 《大地构造与成矿学》1993,17(3):271-288

拉卡兰褶皱带中,发育于Ballarat-Bandigo冲断带中的低级变质砂、泥岩的宏观构造以间离劈理和人字形褶皱为特征,而且劈理在褶皱中呈扇形发育。劈理和褶皱的几何关系分析显示:劈理和褶皱的形成为压溶作用、压扁作用、弯曲作用和被动旋转共同作用的结果,而褶皱砂、泥岩中变形构造则以与压溶作用和再沉淀过程有关的显微构造为其典型特征。Fry法进行的全岩应变测量显示,褶皱砂岩的内部应变相当低(X/Z=1.40—1.83),褶皱应变格局给出变形机制的信息包括:缩短过程中的压扁作用和压溶作用、褶皱过程中由弯滑导致的层平行剪应变、以及褶皱后期发育阶段内弧区强烈的压溶作用。宏观构造、显散构造以及应变特征多方面信息证明:低级变质的沉积岩在褶皱变形过程中,压溶作用为一重要的变形机制。应变分解显示在30％—50％的总地壳水平缩短量下,弯曲导致的缩短最为14％—36％,压扁导致的缩短量为3％—14％,压溶导致的缩短量为8％—26％,而且压溶作用主要发生在褶皱内弧区。  相似文献   

吉林省印支运动的意义及有关问题的探讨     

翟斗烈 《吉林地质》1990,9(1):65-68

早印支运动结束了吉林省北部地槽的发展进程,从而南台北槽统一为一体。早印支运动具有华力西构造运动的继承性,晚印文运动时期则具有中生代构造运动的新生性特点。北部地槽是递进式封闭的华力西地槽印支皱褶带。印支运动时期是在亚洲大陆与太平洋构造体系中首次出现大陆边缘活化带的新起点。  相似文献   

大陆韧性伸展构造系统解析纲要   总被引：5，自引：0，他引：5  

单文琅  傅昭仁 《地球科学》1991,16(5):515-522

  相似文献   

区域变质岩区填图的构造地层学准则   总被引：8，自引：0，他引：8  

单文琅  傅昭仁 《地球科学》1987,(5)

区域变质岩区填图工作的关键问题是能否或如何在“地层学”意义上来划分填图单位。鉴于变质岩的构造特殊性,公认应当采用构造-地层方法,但是这里涉及的不单纯是工作程序和具体方法,而且涉及对变质构造特征的理论认识。本文以北京西山浅变质岩系为例,对构造地层学准则进行初探,因为这里可明确建立双重地层系统,便于对比分析。  相似文献   

Evolution of localized folding for a thin elastic layer in a softening visco-elastic medium   总被引：1，自引：0，他引：1  

G. W. Hunt  H-B. Mühlhaus  A. I. M. Whiting 《Pure and Applied Geophysics》1996,146(2):229-252

Long compressed elastic struts on softening elastic foundations have a tendency to buckle locally. The same tendency is demonstrated here for the instantaneous response of elastic struts supported by visco-elastic media. A governing nonlinear partial differential equation is derived to describe the evolution of the localized form in time. Under the assumed constant end-shortening this is found to be approximated by a coupled set of seven ordinary differential (diffusion) equations. As the load drops to zero, the localized buckle pattern evolves towards the form of the single long wave, but remains aperiodic for all time. Three-dimensional plots show how this localized pattern changes over time.  相似文献   

Synfolding magnetization: detection, testing and geological applications   总被引：1，自引：0，他引：1  

Stanislav V. Shipunov 《Geophysical Journal International》1997,130(2):405-410

A correct method for determining the direction of a synfolding remanence is described, and a new test, which in a number of cases can discriminate between a true synfolding remanence and a remanence that is the sum of pre- and post-folding components, is suggested. It is shown that it is possible to reveal the folding evolution of a local object under an assumption that the acquisition of the synfolding remanence was synchronous over this object.  相似文献   

Remarkable Cave,Tasmania     

I. McDougall 《Australian Journal of Earth Sciences》2016,63(1):91-97

At Remarkable Cave, southern Tasmania, Triasssic sedimentary rocks are intruded by Jurassic dolerite to form a sheet-like body of unknown thickness to the east of and below Remarkable Cave. The sedimentary rocks near sea-level at Remarkable Cave show deformation and flow structures, and are composed of recrystallised predominantly quartz and feldspar with some darker alteration minerals and zeolite in the more massive parts of the recrystallised rock. The deformation was caused by the intrusion of dolerite. At the top of the sheet-like body to the east of Remarkable Cave there is rheomorphic veining into the dolerite following joint fractures. The dolerite is locally transgressive. In Remarkable Cave, dolerite must occur just below the floor of the cave to heat the sedimentary rocks to much higher temperatures than typical contact aureoles in the area, supporting a local feeder geometry, or compositional control.  相似文献   

1990年共和7.0级地震的发震构造讨论   总被引：2，自引：0，他引：2       下载免费PDF全文

陈玉华  张敏  张晓青  朱德瑜  肖振敏 《地震工程学报》1998,20(3):39-43

根据地质、地震及形变资料研究了１９９０年４月青海省共和ＭＳ７．０地震的发震构造．认为ＮＷＮＷＷ向的哇玉香卡拉干逆冲盲断裂是该次地震的发震构造．其地表形变以褶皱隆起为主．因此,共和地震是一次典型的“盲断裂褶皱地震”．  相似文献   

Regional and Global Tropopause Fold Occurrence and Related Ozone Flux Across the Tropopause     

M. Beekmann  G. Ancellet  S. Blonsky  D. De Muer  A. Ebel  H. Elbern  J. Hendricks  J. Kowol  C. Mancier  R. Sladkovic  H. G. J. Smit  P. Speth  T. Trickl  Ph. Van Haver 《Journal of Atmospheric Chemistry》1997,28(1-3):29-44

This paper gives a synthesis of three algorithms to detect the presenceof tropopause folds from vertical ozone/radio-sounding profiles and frommeteorological analysis. Also an algorithm to identify injection ofstratospheric air into the lower troposphere fromozone/⁷beryllium time series is presented. Differences in theresults obtained from the algorithms are observed and discussed with respectto the criteria for fold detection and input data used. Spatial gradients inthe obtained folding frequencies are made evident on a global scale from thealgorithm based on meteorological analysis (Q-vector/potential vorticity)and probably also on a regional European scale from algorithms both basedmeteorological analyses and on ozone/PTU soundings. The observed seasonalvariation of folding occurrence is rather flat except during summer whenalso some differences appear between the algorithms. By combining thefolding frequencies with literature estimates of the cross-tropopause ozonetransfer in single folding events, an average stratospheric ozone influxinto the troposphere of 5.7 ± 1.3× 10¹⁰ mol.cm^-2 s^-1 is obtained for the Northern hemisphereand 12± 2.7× 10¹⁰ mol. cm^-2s^-1 for Western Europe. Potential additional contributions dueto other stratosphere-troposphere exchange processes than folds are not yetincluded in these estimates. Finally, the link between statistics fromozone/⁷beryllium data and folding statistics is brieflydiscussed.  相似文献   

川东明月峡双重楔形构造叠加模式     

杨庚  陈竹新  王晓波 《地质论评》2021,67(4):67040901-67040917

川东隔挡式褶皱由一系列北东走向的线性褶皱带组成,为典型的高陡背斜构造带。该区油气勘探目的层主要集中在中浅层石炭系,而且钻井主要位于构造核部,钻井深度相对较浅,由于地震资料对构造陡翼地层的反射资料显示品质较差,从而对该构造认识出现了多种解释结果。笔者应用断层相关褶皱理论,依据钻井资料标定,对川东褶皱带典型构造明月峡背斜构造的二维地震剖面测网及两条宽线二维地震剖面重新进行详细构造分析及解释。解释结果表明,如果假定地层厚度不变,明月峡构造样式可以认为是两个楔形构造垂向上叠合而成,发育两期构造。据此本文提出了明月峡背斜双楔形构造发育几何学模式图,分析了两期楔形构造垂向上叠加模式。根据已有的研究成果,地表变形是深部逆冲作用的结果,推测早期中浅层构造变形时间为中白垩世,晚期深层构造为晚新生代时期,而且晚期构造改造了早期构造。构造解释结果给出,剖面几何形态为浅层发育向东的反冲断层扩展褶皱,中深层分别以三叠系膏岩和志留系泥页岩为顶、底滑脱面的楔形构造,深层构造分别以志留系泥页岩和震旦系泥页岩为顶、底滑脱面的楔形构造。构造几何分析指出,深层楔形构造形成时间晚于中深层楔形构造,并改造了早期中深层楔形构造,从而出现了构造高点的向西偏移的现象。在平面分布上,明月峡背斜浅层高陡构造背斜东翼宽度从北向南逐渐变窄,深层楔形体楔形角度逐渐变大,构造缩短量相应增加。  相似文献