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1.
《International Geology Review》2012,54(4):365-382
The Tokat Massif is a major metamorphic complex of the south-central Pontides, the origin and development of which have long remained unknown. Recent detailed field-based mapping has revealed the major geological features of this complex. The Tokat Massif appears to be a tectonic mosaic composed of three major components: (1) the Yesilirmak Group; (2) the Turhal Metaophiolite; and (3) the Amasya Group. The Yesilirmak Group, which consists of a coherent lithoiogical sequence involving Paleozoic basement and overlying Triassic units, represents a short-lived basin assemblage. The Turhal Metaophiolite consists of an ophiolitic melange association and slices of a stratigraphically ordered ophiolite. The Amasya Group, the highest-standing tectonic unit, is represented by a lower Paleozoic clastic succession. The different major tectonostratigraphic assemblages of the Tokat Massif record a continent-continent collision between the Laurasian Amasya Group and the Gondwanan Yesilirmak Group. The Turhal Metaophiolite, sandwiched between the two continental fragments, represents remnants of an oceanic realm that was consumed between the two continents. The three major tectonic components were assembled and underwent regional metamorphism during the Late Triassic-Liassic transition, and were later covered during the Liassic by basal detrital units. 相似文献
2.
In the internal part of the Umbro-Marchean-Romagnan Apennines, the foredeep clastic wedge constituting the Neogene part of the sedimentary cover is completely detached from the underlying Mesozoic–Palaeogene succession. The resulting (Umbro-Romagnan) parautochthon consists of tectonostratigraphic units with a general geometry of broad synclinal blocks separated by narrow faulted anticlines.
Thrust-related structures observed in the field require thrust ramp propagation to have occurred within already folded rocks; therefore, they cannot be restored using simple fault-bend fold or fault-propagation folding models. Evidence for a passive fold origin in the studied rocks suggests that an early detachment folding episode preceded ramp propagation. The latter was facilitated by the enhanced thickness of incompetent material in the cores of detachment anticlines, which became the preferential sites where thrust ramps cut up-section. Depending on the trajectory of such thrust ramps, different types of fault-related structures could develop. Hanging-wall anticlines which give way to monoclinal structures higher up in the section are associated with listric thrust ramps, whereas hanging wall monoclines approximately parallel to the underlying fault surface are associated with straight-trajectory ramps.
This kinematic evolution, which occurred partly during syn-depositional compression, also accounts for the observed lithofacies distribution. The latter reflects an early differentiation of the foredeep trough into sub-basins that are progressively younger towards the foreland. The detachment anticlines that originally bounded such sub-basins were the site of later thrust propagation, leading to a tectonic juxtaposition of different tectonostratigraphic units consisting of broad NW-SE elongate synclinal blocks. 相似文献
Thrust-related structures observed in the field require thrust ramp propagation to have occurred within already folded rocks; therefore, they cannot be restored using simple fault-bend fold or fault-propagation folding models. Evidence for a passive fold origin in the studied rocks suggests that an early detachment folding episode preceded ramp propagation. The latter was facilitated by the enhanced thickness of incompetent material in the cores of detachment anticlines, which became the preferential sites where thrust ramps cut up-section. Depending on the trajectory of such thrust ramps, different types of fault-related structures could develop. Hanging-wall anticlines which give way to monoclinal structures higher up in the section are associated with listric thrust ramps, whereas hanging wall monoclines approximately parallel to the underlying fault surface are associated with straight-trajectory ramps.
This kinematic evolution, which occurred partly during syn-depositional compression, also accounts for the observed lithofacies distribution. The latter reflects an early differentiation of the foredeep trough into sub-basins that are progressively younger towards the foreland. The detachment anticlines that originally bounded such sub-basins were the site of later thrust propagation, leading to a tectonic juxtaposition of different tectonostratigraphic units consisting of broad NW-SE elongate synclinal blocks. 相似文献
3.
缅甸大地构造单元的划分与特征 总被引：1，自引：0，他引：1
为合作开发周边国家矿产资源,在实地调研的基础上,结合前人资料的收集与整理,将缅甸的大地构造单元自西向东划分为5个Ⅰ级构造单元、10个Ⅱ级构造单元.具体是：①西克钦邦-若开邦结合带（E-N1）（Ⅰ）,进一步划分为钦邦-若开邦结合带（E-N1）（Ⅰ1）、西克钦邦结合带（E-N1）（Ⅰ2）;②西缅甸-苏门答腊弧盆系（E-N1）（Ⅱ）,进一步划分为蒙育瓦-勃生岛弧带（E-N1）（Ⅱ1）、瑞保-仰光弧后盆地（E-N1）（Ⅱ2）、密支那岛弧带（E-N1）（Ⅱ3）;③腾冲-马来半岛造山带（T3-K）（Ⅲ）,进一步划分为八莫陆缘弧（T3-K）（Ⅲ1）、毛淡棉陆缘弧（T3-K）（Ⅲ2）、德林依达地块（Pz2）（Ⅲ3）;④保山-掸邦陆块（€-T2）（Ⅳ）;⑤昌宁-孟连-清莱结合带（C-T2）（Ⅴ）.这10个构造单元以9条断裂为边界.自西向东为：那加山-若开山逆冲断裂（F1）、平梨铺-卑谬伸展断裂（F2）、实皆-勃固右行平移断裂（F3）、葡萄-格杜逆冲断裂（F4）、英昆-八莫伸展断裂（F5）、南坎-抹谷右行平移断裂（F6）、曼德勒-垒固左行平移断裂（F7）、锡当-三塔左行平移断裂（F8）、孟宾-清迈逆冲断裂（F9）. 相似文献
4.
合理厘定西南天山构造属性,不仅对天山大地构造单元的准确划分具有重要科学意义,而且对中亚造山带的古生代构造演化也至关重要。通过对西南天山乌什北山地区的地质填图和构造解析,识别出5期构造变形,包括2期逆冲推覆构造。对主期逆冲推覆构造进行几何学、运动学研究表明,该逆冲推覆构造在空间上具有由北向南逆冲的运动学指向,并由北向南表现出由逆冲推覆构造的根带向前锋带变化的构造样式。根据逆冲推覆构造的物质组成及变形样式,认为西南天山乌什北山一带应属于塔里木板块北缘逆冲推覆构造带,从而为区域构造单元划分及西南天山晚古生代以来的构造演化过程提供构造变形方面的依据。 相似文献
5.
通过1/25万四子王旗幅的野外地质填图,在蒙古寺-盘羊山-乌兰合雅一线存在古生代末大型逆冲推覆构造系统,新太古代色尔腾山岩群和新太古代花岗岩自北向南被逆冲推覆于震旦系什那干组灰岩和古生代碎屑岩之上,并形成大小规模的飞来峰和构造窗。整个推覆系统由顶板逆冲断层与底板逆冲断层及夹于其中的一套叠瓦式逆冲断层和断层夹块组合而成,构成典型的双重逆冲推覆构造系统(Duplex)。该逆冲推覆构造总体逆冲方向指向南南西向,形成时代为二叠纪末,估算推覆距离应大于7.1 km。此逆冲推覆构造与华北板块与西伯利亚板块在二叠纪末陆内碰撞造山有关,是华北板块北缘造山带的重要组成部分。 相似文献
6.
北淮阳东段变质构造地层的古构造环境 总被引：1，自引：0，他引：1
关于大别山北麓北淮阳东段原佛子岭岩群的古构造环境问题,存在着认识分歧,其主要原因是将形成构造背景与地质演化历史本不相同的不同构造地层单元混在了一起,不加区分地进行古构造环境分析。根据构造变形、岩相学、岩石地球化学等的综合研究,将原佛子岭岩群解体为被一重要的构造滑脱带所分隔的下部卢镇关构造混杂岩带和上部诸佛庵岩群。通过对新厘定的构造岩石地层单元分别进行沉积建造和岩石化学、地球化学特征的研究发现,下部卢镇关构造混杂岩带形成于被动大陆边缘环境,而上部诸佛庵岩群形成于华北板块南部活动大陆边缘环境。这意味着华北、扬子板块的古生代板块碰撞缝合带的位置应该位于诸佛庵岩群分布区域的南侧,而且板块俯冲-碰撞的极性表现为扬子板块向华北板块之下俯冲。 相似文献
7.
基础地质调查的首项任务就是查清不同构造-地层区划单元内的地层层序和时代.因此,开展构造-地层区划和建立地层格架,是矿产能源、水文环境和工程地质等工作不可缺少的一项奠基性工作.本文强调构造、沉积和气候环境等对地层发育的主控作用,并提出断代构造-地层区划定义为:是指对一个国家或地区某一地质发展阶段(如新元古代,寒武纪等)内形成的地层,通过对其形成的构造环境、沉积和气候环境、岩石组合、古生物组合、地球物理和地球化学特征等记录的综合调查分析对比后,所进行的地层地理分布划分.根据新含义,本文以中国寒武纪构造-地层区划为实例,拟定出构造-地层区划的主要依据是:全球洋陆重建分布、地层建造大类、基底和盖层地层序列和洋陆转化时间、地层序列完整性与接触关系、地层岩性岩相序列对比、造山带对接缝合带洋板块地层分布与特征、造山带叠接缝合带洋板块地层分布与特征、生物古地理区系、构造-岩相古地理格局、古气候分区、区划边界11条识别标志. 相似文献
8.
《International Geology Review》2012,54(1):32-50
The main Precambrian tectonic units of Uruguay include the Piedra Alta tectonostratigraphic terrane (PATT) and Nico Pérez tectonostratigraphic terrane (NPTT), separated by the Sarandí del Yí high-strain zone. Both terranes are well exposed in the Río de La Plata craton (RPC). Although these tectonic units are geographically small, they record a wide span of geologic time. Therefore improved geological knowledge of this area provides a fuller understanding of the evolution of the core of South America. The PATT is constituted by low- to medium-grade metamorphic belts (ca. 2.1 Ga); its petrotectonic associations such as metavolcanic units, conglomerates, banded iron formations, and turbiditic deposits suggest a back-arc or a trench-basin setting. Also in the PATT, a late to post-orogenic, arc-related layered mafic complex (2.3–1.9 Ga), followed by A-type granites (2.08 Ga), and finally a taphrogenic mafic dike swarm (1.78 Ga) occur. The less thoroughly studied NPTT consists of Palaeoproterozoic high-grade metamorphic sequences (ca. 2.2 Ga), mylonites and postorogenic and rapakivi granites (1.75 Ga). The Brasiliano-Pan African orogeny affected this terrane. Neoproterozoic cover occurs in both tectonostratigraphic terranes, but is more developed in the NPTT. Over the past 15 years, new isotopic studies have improved our recognition of different tectonic events and associated processes, such as reactivation of shear zones and fluids circulation. Transamazonian and Statherian tectonic events were recognized in the RPC. Based on magmatism, deformation, basin development and metamorphism, we propose a scheme for the Precambrian tectonic evolution of Uruguay, which is summarized in the first Palaeoproterozoic tectonic map of the Río de La Plata craton. 相似文献
9.
马尼干戈第四系盆地河流阶地具有"砾石分选、磨圆差,分层结构不明显"的物质组成、"沿玉曲河南岸单侧发育、具菱形状阶地"的分布和形态及"第Ⅲ级阶地因次第升降而裂解"的构造特征等。因此推断马尼干戈盆地可能是区域上三大构造单元—"南部义敦群域辗掩系统(义敦岛弧带)、中部结合群域原地系统(甘孜-理塘结合带北段)和北部西康群域辗掩系统(西康群)"晚近期不均衡抬升(块断升降)引起局部断陷成盆、并叠加左行走滑拉分而形成的。这一发现对松潘-甘孜造山带第四纪新构造期活动的研究具有重要意义。 相似文献
10.
青藏高原北羌塘地区晚三叠世地层展布和沉积型式 总被引：10，自引：3，他引：10
北羌塘盆地地处拉竹龙-金沙江缝合带和双湖构造混杂岩带之间,自北向南可划分出5个沉积相带/岩石地层单位：以砂泥质复理石-洋岛、岛弧型火山岩-大理岩岩石组合沉积为特征的若拉岗日群,以深水复理石盆地相沉积为特征的藏夏河组,以深水暗色细碎屑岩盆地相沉积为特征的结扎群,以开阔台地相/缓坡相碳酸盐岩沉积为特征的菊花山组,以三角洲相含煤碎屑岩系沉积为特征的土门格拉群.晚三叠世北羌塘盆地显示为南缓北陡的箕状沉积格局,盆地内充填物为南薄北厚的楔形沉积体,且双物源、沉降中心和沉积中心不一致,表明其具有前陆盆地的一系列沉积特征. 相似文献
11.
东昆仑南缘晚古生代地层组合、大地构造相及大地构造意义 总被引：1，自引：0，他引：1
现代大陆边缘盆地研究结果显示,仅根据蛇绿岩分布划分大地构造单元、分析构造演化可能得出误导性结果.而详细的沉积建造分析、结合其他地质资料可以得到更可靠的结论.东昆仑南缘西段1∶25万区域地质调查显示,该区晚古生代地层为一套不含火山岩的碎屑岩-碳酸盐岩组合,从石炭系到三叠系,由北往南沉积建造由陆缘碎屑岩逐步转化为深海浊积岩,显示典型被动陆缘构造环境.这种特点表明,东昆仑南缘蛇绿岩并不代表成熟大洋地壳残片,而是发育于夭折裂谷环境的初始洋盆;其代表位于研究区以南地区的金沙江古特提斯洋盆的北部被动陆缘(现代地理方位).研究区内不整合覆盖在晚古生代地层之上的侏罗系磨拉石建造代表碰撞造山晚期的上叠前陆盆地,表明印支期造山旋回的结束. 相似文献
12.
雅鲁藏布江缝合带内构造岩片划分及形成——以仲巴-桑桑段为例 总被引：1，自引：2，他引：1
构造岩片作为造山带中非史密斯地层地区的填图单位有其重要的地质意义,本文将雅鲁藏布江缝合带分为6大构造岩片,其中蛇绿混杂岩岩片又分4个次级岩片,进一步阐述了缝合带内不同单元具有不同岩性和不同构造型式,是一条复杂的构造带,并发现俯冲板块一侧的不同构造单元具有自南而北,由脆性变形到低温高压变质、脆-韧性变形,超基性岩的深层次韧性变形的分布规律,大多数岩片的分布是通过多重逆冲推覆型或走滑型的断层将其从地壳深部挤出定位的。雅鲁藏布江缝合带内的构造岩片特征,反映了冈瓦那大陆北缘自三叠纪末期到第四纪经历了裂陷、扩张、多岛洋、闭合、俯冲、碰撞、褶皱、推覆造山的全过程。 相似文献
13.
《International Geology Review》2012,54(8):778-786
The Mersin ophiolite is an ～6-km-thick oceanic crustal sequence in the central Taurides (southern Turkey), forming large outcrops on the southern flank of Bolkardag. It comprises a sequence of units and includes, in ascending structural order, the Mersin melange, subophiolitic metamorphics, tectonics, ultramafic and mafic cumulates, and pillow lavas interlayered with deep-marine sediments. Thin beds of ophiolite-related metamorphics occupy a constant stratigraphic position at the base of the thick ultramafic unit and include a characteristic rock association of amphibolite and amphibolitic schist, epidote-amphibole schist, quartz-mica schist, calcschist, and marble, which exhibits a typical inverted metamorphic zonation from upper amphibolite to greenschist facies. The protoliths of these metamorphics are oceanic-island basaltic rocks and associated pelagic sediments. They are cut by a swarm of approximately E-W-trending, post-metamorphic, MORB-type tholeiite, microgabbroic-diabasic dikes, which are seen not to affect the structurally overlying harzburgites. The initial detachment of these metamorphics from the oceanic crust during closure of the Neotethyan ocean commenced in the late Cenomanian (96 to 92 Ma, 40Ar/39Ar hornblende ages). The metamorphics have a well-developed migmatitic structure and metamorphic banding defined by alternating epidote-rich and carbonate layers. A pronounced regional foliation (S1), NW-SE-trending mineral lineation (L1), and first-order intrafolial folds (F1) were produced during their deformation. Imbricated structure also is typical in these metamorphics. The meso-structures-such as asymmetry of calcite-augen, vergence and asymmetry of F1 folds, general trend of brittle-ductile structures such as oblique-slip normal and thrust/reverse faults, and vergence of thrusts in the imbricate structure—all indicate unambiguous non-coaxial deformation and a shear sense of upper levels moving up to the NW. The structural evidence suggests that the Mersin ophiolite was obducted over the Bolkardag Mesozoic carbonates from the SE to the NW. The shear sense obtained from the subophiolitic metamorphics is compatible with the general trend and vergence of the large-scale thrust sheets that comprise the Mersin ophiolite. 相似文献
14.
Correlation of Tectono-Stratigraphic Units in Northern Thailand with Those of Western Yunnan (China)
Chongpan Chonglakmani School of Geotechnology Suranaree University of Technology Nakhon Ratchasima ThailandFeng Qinglai Faculty of Earth Sciences China University of Geosciences Wuhan Dieter Meischner Goettingen Center of Geosciences 《中国地质大学学报(英文版)》2001,12(3)
Ｔｈｅｃｏｒｒｅｌａｔｉｏｎｏｆｔｅｃｔｏｎｏ ｓｔｒａｔｉｇｒａｐｈｉｃｕｎｉｔｓｏｆＮｏｒｔｈｅｒｎＴｈａｉｌａｎｄｗｉｔｈｔｈｏｓｅｏｆＷｅｓｔｅｒｎＹｕｎｎａｎ (Ｃｈｉｎａ)ｉｓｓｔｉｌｌｌｉｔｔｌｅｕｎｄｅｒｓｔｏｏｄ ,ｐａｒｔｌｙｂｅｃａｕｓｅｏｆｔｈｅ ｐａｕｃｉｔｙｏｆｇｅｏｌｏｇｉｃａｌｄａｔａｆｒｏｍｔｈｅＵｎｉｏｎｏｆＭｙａｎｍａｒａｎｄｔｈｅＬａｏｓ,ａｎｄｐａｒｔｌｙｄｕｅｔｏｔｈｅｃｏｎｆｌｉｃｔｉｎｇｇｅｏｄｙｎａｍｉｃｃｏｎｃｅｐｔｓａｄｏｐｔｅｄｂｙｖａｒｉｏｕｓａ… 相似文献
15.
福建省构造运动,构造层划分及其主要特征 总被引：10，自引：0，他引：10
研究构造运动及构造层特征是查明地壳构造演化历史的重要证据,从福建省目前建立的地层序列分析,自古元古代以来,省内初步可划分出１５次构造运动,并分别归属迪口,晋宁,加里东,印支,燕山,喜马拉雅６个构造旋回,文中对地震旦纪地层次建立构造地层单位,并阐述了各构造运动,构造旋回,构造阶段和构造层,亚构造层的基本特征,较系统地反映了福建省地壳构造演化历史。 相似文献
16.
Stefano Ceriani Bernhard Fügenschuh Stefan M. Schmid 《International Journal of Earth Sciences》2001,90(3):685-702
The different segments of the tectonic boundary between external (European) and internal (Penninic) units in the Western Alps, the so-called Penninic Front (PF), formed at different times and according to different kinematic scenarios. During a first episode (Eocene), the PF corresponds to a transpressive suture zone between Penninic and European units. North- to NNW-trending stretching lineations, found along internal nappe contacts within the Penninic units, are related to this episode. This subduction zone was sealed by the Priabonian flysch of the Aiguilles d'Arves, a detrital trench formation that formed during the final stages of subduction. During a second episode, starting in mid-Oligocene times, the PF, imaged along the ECORS-CROP profile, acted as a WNW-directed thrust. This thrust, the Roselend Thrust (RT), only partially coincides with the PF. South of Moûtiers, the RT propagates into the Dauphinois units, carrying the former Eocene PF (including the Priabonian flysch) passively in its hangingwall. South of the Pelvoux massif the RT finds its continuation along the "Briançonnais Front", an out-of-sequence thrust behind the Embrunais-Ubaye nappes. On a larger scale, our findings indicate oblique (sinistral) collision within the future Western Alps during the Eocene, followed by westward indentation of the Adriatic block. 相似文献
17.
Sedimentary genesis and lithostratigraphy of Neoproterozoic megabreccia from Mufulira, Copperbelt of Zambia 总被引：1，自引：0，他引：1
Marek Wendorff 《Journal of African Earth Sciences》2005,42(1-5):61
The Lufilian arc is an orogenic belt in central Africa that extends between Zambia and the Democratic Republic of Congo (DRC) and deforms the Neoproterozoic-Lower Palaeozoic metasedimentary succession of the Katanga Supergroup. The arc contains thick bodies of fragmental rocks that include blocks reaching several kilometres in size. Some megablocks contain Cu and Cu–Co-mineralised Katangan strata. These coarse clastic rocks, called the Katangan megabreccias, have traditionally been interpreted in the DRC as tectonic breccias formed during Lufilian orogenesis due to friction underneath Katangan nappes. In mid-90th, several occurrences in Zambia have been interpreted in the same manner. Prominent among them is an occurrence at Mufulira, considered by previous workers as a ≈1000 m thick tectonic friction breccia containing a Cu–Co-mineralised megablock.This paper presents new results pertaining to the lower stratigraphic interval of the Katanga Supergroup at Mufulira and represented by the Roan Group and the succeeding Mwashya Subgroup of the Guba Group. The interval interpreted in the past as tectonic Roan megabreccia appears to be an almost intact sedimentary succession, the lower part of which consists of Roan Group carbonate rocks with siliciclastic intercalations containing several interbeds of matrix-supported conglomerate. A Cu–Co-mineralised interval is not an allochthonous block but a part of the stratigraphic succession underlain and overlain by conglomerate beds, which were considered in the past as tectonic friction breccias. The overlying megabreccia is a syn-rift sedimentary olistostrome succession that rests upon the Roan strata with a subtle local unconformity. The olistostrome succession consists of three complexes typified by matrix-supported debris-flow conglomerates with Roan clasts. Some of the conglomerate beds pass upwards to normally graded turbidite layers and are accompanied by solitary slump beds. The three conglomeratic assemblages are separated by two intervals of sedimentary breccia composed of allochthonous Roan blocks interpreted as mass-wasting debris redeposited into the basin by high-volume sediment-gravity flows. Sedimentary features are the primary characteristics of the conglomerate interbeds in the Roan succession and of the overlying megabreccia (olistostrome) sequence. Both lithological associations are slightly sheared and brecciated in places, but stratigraphic continuity is retained throughout their succession. The olistostrome is deformed by an open fold, the upper limb of which is truncated by and involved in a shear zone that extends upwards into Mwashya Subgroup strata thrust above.Based on the sedimentary genesis of the megabreccia, local tectonostratigraphic relations and correlation with the succession present in the Kafue anticline to the west, the Mwashya Subgroup, formerly considered as a twofold unit, is redefined here as a three-part succession. The lower Mwashya consists of an olistostrome complex defined as the Mufulira Formation, the middle Mwashya (formerly lower Mwashya) is a mixed succession of siliciclastic and carbonate strata locally containing silicified ooids and tuff interbeds, and the term upper Mwashya is retained for a succession of black shales with varying proportions of siltstone and sandstone interlayers. The sedimentary genesis and stratigraphic relations of the megabreccia at Mufulira imply that the position and tectonostratigraphic context of the Katangan Cu and Cu–Co orebodies hosted in megablocks associated with fragmental rocks, which were in the past interpreted as tectonic friction breccias, need to be critically re-assessed in the whole Lufilian arc. 相似文献
18.
Existence of a possible detachment zone at Elampillai region, NW margin of Kanjamalai Hills, located in the northern part of Cauvery Suture Zone (CSZ), Southern India, is reported here for the first time. Detailed structural mapping provides anatomy of the zone, which are rarely preserved in Precambrian high grade terranes. The detachment surface separates two distinct rock units of contrasting lithological and structural characters: the upper and lower units. The detachment zone is characterized by a variety of fold styles with the predominance of tight isoclinal folds with varied plunge directions, limb rotations and the hinge line variations often leading to lift-off fold like geometries and deformed sheath folds. Presence of parasitic folding and associated penetrative strains seem to be controlled by differences in mechanical stratigraphy, relative thicknesses of the competent and incompetent units, and the structural relief of the underlying basement. Our present study in conjunction with other available geological, geochemical and geochronological data from the region indicates that the structures of the detachment zone are genetically related to thrust tectonics forming a part of subduction–accretion–collision tectonic history of the Neoproterozoic Gondwana suture. 相似文献
19.
The Monferrato is a key area of the Alps-Apennine junction. It consists of a Tertiary succession, resting on Apennine-related units, in turn overridden by the Alpine basement. The superficial expression of this crustal discontinuity is the Rio Freddo deformation zone, separating the Alpine-related Torino hill domain from the Monferrato. Stratigraphic analyses allow the recognition of different fault-bounded Oligo-Miocene successions, interpreted as tectonostratigraphic units. Some of these corresponded to high-standing blocks, others to subsiding basins. The facies distribution reflects a transpressional tectonic regime. In this general framework of wrench tectonics, sedimentation was influenced by palaeoceanographic factors during the early and latest Burdigalian, while tectonics played the dominant role during the Aquitanian and the late Burdigalian. The uniform extent and the unconformable basal boundary of the Langhian deposits suggest that the different tectonostratigraphic units presently composing the Monferrato area were in place by Langhian times. 相似文献
20.
西藏金沙江缝合带西段晚三叠世碰撞作用与沉积响应 总被引：17，自引：4，他引：17
青藏高原是由若干条缝合带和其间所夹的沉积盆地构成,其中晚三叠世北羌塘盆地位于金沙江缝合带南缘,盆地的充填实体显示为南薄北厚,为楔形沉积体;在垂向上,以不整合面为界可将该套充填地层划分为两个构造层序,下部构造层序以复理石建造为特征,上部构造层序以磨拉石建造为特征,具有典型的前陆盆地充填序列;盆地具双物源和双古流向体制,沉降中心和沉积中心具有不一致,显示其为金沙江缝合带南侧的周缘前陆盆地,从而确定了晚三叠世北羌塘前陆盆地与金沙江缝合带的成因关系。在此基础上,结合在金沙江缝合带西段新发现和确定的蛇绿岩的最小年龄和碰撞型花岗岩的年龄,本文根据下部构造层序复理石的年龄、前缘隆起的形成年龄、冲断带隆升成为地貌高地的年龄、下部不整合面的时代和前缘隆起型碳酸岩缓坡的形成时间标定了金沙江缝合带碰撞事件的时代下限,根据上部构造层序磨拉石的年龄、上部不整合面的年龄、花岗岩和构造碎裂岩成为物源的年龄标定了金沙江缝合带碰撞事件的时代上限,表明金沙江缝合带初始碰撞事件为卡尼克期与诺利克期之间,最终碰撞事件介于诺利克期与瑞替克期之间. 相似文献