CAJ | 학술논문

大别-苏鲁造山带不同岩片(块)经历了不同的褶皱变形.榴辉岩块(或透镜体)和硬玉石英岩片经历了高压-超高压背景下的两幕褶皱变形之后,在区域性第一幕变形期间主要发生透镜化为主,后期与围岩共同经历紧闭同斜第二幕褶皱.而其它岩片主要经历了现今野外可见的区域性三幕褶皱,其中区域性第一幕褶皱为片内残留褶皱,在斜长角闪岩透镜体中多见,宏观规律不明.区域性第二幕褶皱在露头尺度多见,轴面为折劈理,局部强烈置换成片理化带(复合片理或第二期片理),恢复第三幕褶皱改造作用后,揭示出各种岩片中的各级尺度的第二幕褶皱都为轴面北西倾南东倒、轴迹走向为NNE向的紧闭不对称褶皱,不对称性一致反映其指向与各种岩片向南东的逆冲运动有关.第三幕褶皱为以片理或折劈理为变形面的宽缓褶皱,轴迹走向NWW,枢纽向西倾伏.韧性剪切带为非透入性构造,分早晚两期,早期为韧性逆冲,新县穹隆以南,运动学标志指示向北逆冲,错切第二幕褶皱,结合新县穹隆北部向南的逆冲特征,反映这些韧性逆冲断层多数为第二幕大型褶皱翼部的次级逆冲断层;晚期为韧性滑脱带,其发育局限于几个岩性差异较大的接触带,带内伸展型折劈理发育,并对挤压构造样式有重要的改造作用.华北克拉通东部地块是华北克拉通的重要组成,其盖层古生界和三叠系在印支运动期间经历了一幕宽缓褶皱作用,其轴迹方向主体也为NWW向.这一褶皱构造明显在变形时间、变形样式和展布方向上都和大别-苏鲁造山带中的第三幕褶皱非常一致,说明它们具有动力学上的必然联系.同时,研究表明在华北克拉通东部地块中没有经历大别-苏鲁造山带中区域性第一、第二幕褶皱变形的记录,故本文认为印支期这两幕变形主要发生在华北板块东南缘的边界上,并没有波及到板内,而且从东向西高压-超高压岩石剥露具有穿时性.只有当华北板块和华南板块在第二幕变形之后构成了统一块体后,第三幕变形才波及华北板内. 大彆-囌魯造山帶不同巖片(塊)經歷瞭不同的褶皺變形.榴輝巖塊(或透鏡體)和硬玉石英巖片經歷瞭高壓-超高壓揹景下的兩幕褶皺變形之後,在區域性第一幕變形期間主要髮生透鏡化為主,後期與圍巖共同經歷緊閉同斜第二幕褶皺.而其它巖片主要經歷瞭現今野外可見的區域性三幕褶皺,其中區域性第一幕褶皺為片內殘留褶皺,在斜長角閃巖透鏡體中多見,宏觀規律不明.區域性第二幕褶皺在露頭呎度多見,軸麵為摺劈理,跼部彊烈置換成片理化帶(複閤片理或第二期片理),恢複第三幕褶皺改造作用後,揭示齣各種巖片中的各級呎度的第二幕褶皺都為軸麵北西傾南東倒、軸跡走嚮為NNE嚮的緊閉不對稱褶皺,不對稱性一緻反映其指嚮與各種巖片嚮南東的逆遲運動有關.第三幕褶皺為以片理或摺劈理為變形麵的寬緩褶皺,軸跡走嚮NWW,樞紐嚮西傾伏.韌性剪切帶為非透入性構造,分早晚兩期,早期為韌性逆遲,新縣穹隆以南,運動學標誌指示嚮北逆遲,錯切第二幕褶皺,結閤新縣穹隆北部嚮南的逆遲特徵,反映這些韌性逆遲斷層多數為第二幕大型褶皺翼部的次級逆遲斷層;晚期為韌性滑脫帶,其髮育跼限于幾箇巖性差異較大的接觸帶,帶內伸展型摺劈理髮育,併對擠壓構造樣式有重要的改造作用.華北剋拉通東部地塊是華北剋拉通的重要組成,其蓋層古生界和三疊繫在印支運動期間經歷瞭一幕寬緩褶皺作用,其軸跡方嚮主體也為NWW嚮.這一褶皺構造明顯在變形時間、變形樣式和展佈方嚮上都和大彆-囌魯造山帶中的第三幕褶皺非常一緻,說明它們具有動力學上的必然聯繫.同時,研究錶明在華北剋拉通東部地塊中沒有經歷大彆-囌魯造山帶中區域性第一、第二幕褶皺變形的記錄,故本文認為印支期這兩幕變形主要髮生在華北闆塊東南緣的邊界上,併沒有波及到闆內,而且從東嚮西高壓-超高壓巖石剝露具有穿時性.隻有噹華北闆塊和華南闆塊在第二幕變形之後構成瞭統一塊體後,第三幕變形纔波及華北闆內.
대별-소로조산대불동암편(괴)경력료불동적습추변형.류휘암괴(혹투경체)화경옥석영암편경력료고압-초고압배경하적량막습추변형지후,재구역성제일막변형기간주요발생투경화위주,후기여위암공동경력긴폐동사제이막습추.이기타암편주요경력료현금야외가견적구역성삼막습추,기중구역성제일막습추위편내잔류습추,재사장각섬암투경체중다견,굉관규률불명.구역성제이막습추재로두척도다견,축면위절벽리,국부강렬치환성편이화대(복합편리혹제이기편리),회복제삼막습추개조작용후,게시출각충암편중적각급척도적제이막습추도위축면북서경남동도、축적주향위NNE향적긴폐불대칭습추,불대칭성일치반영기지향여각충암편향남동적역충운동유관.제삼막습추위이편리혹절벽리위변형면적관완습추,축적주향NWW,추뉴향서경복.인성전절대위비투입성구조,분조만량기,조기위인성역충,신현궁륭이남,운동학표지지시향북역충,착절제이막습추,결합신현궁륭북부향남적역충특정,반영저사인성역충단층다수위제이막대형습추익부적차급역충단층;만기위인성활탈대,기발육국한우궤개암성차이교대적접촉대,대내신전형절벽리발육,병대제압구조양식유중요적개조작용.화북극랍통동부지괴시화북극랍통적중요조성,기개층고생계화삼첩계재인지운동기간경력료일막관완습추작용,기축적방향주체야위NWW향.저일습추구조명현재변형시간、변형양식화전포방향상도화대별-소로조산대중적제삼막습추비상일치,설명타문구유동역학상적필연련계.동시,연구표명재화북극랍통동부지괴중몰유경력대별-소로조산대중구역성제일、제이막습추변형적기록,고본문인위인지기저량막변형주요발생재화북판괴동남연적변계상,병몰유파급도판내,이차종동향서고압-초고압암석박로구유천시성.지유당화북판괴화화남판괴재제이막변형지후구성료통일괴체후,제삼막변형재파급화북판내.
The Dabie-Sulu orogen consists of different slices and blocks undergoing multiple-stage folding and thrusting. Particularly some eclogite blocks and jadeite quartzite units underwent two-stage pre-UHP and syn-UHP deformatiom, following boudin-making and slicing during regional first-stage ( D_1 ) deformation and D_2 folding during the regional second-stage deformation. However, other slices or units only underwent mainly regional three-stage folding. The regional first-stage deformation is shown as intra-folial minor folds, mainly preserved in amphibolite blocks. The regional second-stage deformation is commonly outcrop-scale. Its fold axial plane is crenulation cleavage, locally being foliated composite schistosity belt due to intensive displacement. After restoration of D_3 folding, it is shown that axial planes of different-scale tight, asymmetric D_2 folds in different units are southeastern-overturned and NNE-striking. D_2 fold asymmetry implies that it is related to southeast-directed thrusting. The third-stage folds are open folds with NWW-strike, western plunge consisting of deformed schistosity and crenulation cleavage. Unpenetrative ductile shearing related to these folding has two stages. The early ductile shear thrusting is south-directed in the north of the Xinxian dome and south-directed in the north of the Xinxian dome, cutting the second-stage folds and being associated with secondary-scale thrusts by the limb of the second-stage large-scale folds. The later ductile decolloment zones only developed in the contact belts of obvious rock types around the Xinxian dome, with extensional crenulation cleavage, obviously reforming the previous structures. The Eastern Block is an important tectonic unit of North China Craton located at the hanging wall of the Dabie-Sulu organ, of which Paleozoic to Triassic sedimentary cover underwent one-stage regional folding during Indosinian(Late Triassic). Its axial trace is NWW-striking. It is consistent with that of the third-stage folds in the aspects of deformation time and fold style and spatial trending. This implies that they are related in geodynamics. At the same time, this study shows that the Eastern Block didn' t undergo the other earlier regional two-stage deformation in the Dabie-Sulu orogen. Therefore, the two-stage regional Triassic folding has no influence to the inner of North China plate, only happened in the southern margin of North China plate. Only in the case of unifying of North and South China plates after the regional second-stage folding, the third-stage deformation in the Dabie-Sulu orogen induced the first-stage folding in the inner of North China Craton. Diachronous exhumation of HP-UHP rocks in the Dabie-Sulu orogen is related this geodynamic setting and processes of structural evolution.