大地构造与成矿学
大地構造與成礦學
대지구조여성광학
GETECTONICA ET METALLOGENIA
2015年
4期
610-615
,共6页
董有浦%坚润堂%肖安成%李旭英
董有浦%堅潤堂%肖安成%李旭英
동유포%견윤당%초안성%리욱영
褶皱%高角度斜交%构造裂缝%主应变轴%形成机制
褶皺%高角度斜交%構造裂縫%主應變軸%形成機製
습추%고각도사교%구조렬봉%주응변축%형성궤제
fold%high-angle%structural fracture%strain ellipse axes%mechanism
构造裂缝的发育往往与褶皱、断层等构造密切相关,本文对钱塘坳陷南缘富阳–临安地区褶皱岩层中的同褶皱裂缝进行了研究。在褶皱翼部多发育与层面斜交的构造裂缝,具体表现为与层面高角度斜交构造裂缝较为发育,而与层面低角度相交的构造裂缝发育较少或不发育。其中,与层面高角度斜交的构造裂缝的特征与层间剪切作用下形成的裂缝特征不同。分析认为岩层褶皱初期主应变轴与层面平行或直交,在岩层褶皱变形过程中,主应变轴与层面高斜交。岩层外弧受到与层面不平行的拉伸,而内弧则受到与层面不平行的压缩作用。本文认为褶皱过程中应变轴的变化是导致岩层中形成与层面高角度斜交构造裂缝的主要原因。
構造裂縫的髮育往往與褶皺、斷層等構造密切相關,本文對錢塘坳陷南緣富暘–臨安地區褶皺巖層中的同褶皺裂縫進行瞭研究。在褶皺翼部多髮育與層麵斜交的構造裂縫,具體錶現為與層麵高角度斜交構造裂縫較為髮育,而與層麵低角度相交的構造裂縫髮育較少或不髮育。其中,與層麵高角度斜交的構造裂縫的特徵與層間剪切作用下形成的裂縫特徵不同。分析認為巖層褶皺初期主應變軸與層麵平行或直交,在巖層褶皺變形過程中,主應變軸與層麵高斜交。巖層外弧受到與層麵不平行的拉伸,而內弧則受到與層麵不平行的壓縮作用。本文認為褶皺過程中應變軸的變化是導緻巖層中形成與層麵高角度斜交構造裂縫的主要原因。
구조렬봉적발육왕왕여습추、단층등구조밀절상관,본문대전당요함남연부양–림안지구습추암층중적동습추렬봉진행료연구。재습추익부다발육여층면사교적구조렬봉,구체표현위여층면고각도사교구조렬봉교위발육,이여층면저각도상교적구조렬봉발육교소혹불발육。기중,여층면고각도사교적구조렬봉적특정여층간전절작용하형성적렬봉특정불동。분석인위암층습추초기주응변축여층면평행혹직교,재암층습추변형과정중,주응변축여층면고사교。암층외호수도여층면불평행적랍신,이내호칙수도여층면불평행적압축작용。본문인위습추과정중응변축적변화시도치암층중형성여층면고각도사교구조렬봉적주요원인。
Analysis of mechanism of synfolding fracture is the foundation of structure numerical modeling and prediction. Based on the field observation at the Fuyang-Lin’an anticline, Zhejiang, we found that the fractures are apparently high angles to bedding on the fold limbs, and we thus propose that these fractures formed during folding. Characteristics of the fractures show that the high-angle fracture was not resulted from the interlayer-slip. We propose that the high angle fractures were related to the variation of tangential and longitudinal strain during the folding. The direction of strain ellipse axes has a deviation with respect to the directions normal and tangential to the boundaries of the folded layer. In the hinge, strain ellipse axes are perpendicular to the bedding, and on the fold limbs. This mechanism could have led to the formation of high angle fracture.