The Sudbury Structure (Ontario,Canada): a tectonically deformed multi-ring impact basin     

A. Deutsch  R. A. F. Grieve  M. Avermann  L. Bischoff  P. Brockmeyer  D. Buhl  R. Lakomy  V. Müller-Mohr  M. Ostermann  D. Stöffler 《International Journal of Earth Sciences》1995,84(4):697-709

The occurrence of shock metamorphic features substantiates an impact origin for the 1.85 Ga old Sudbury Structure, but this has not been universally accepted. Recent improvements in knowledge of large-scale impact processes, combined with new petrographic, geochemical, geophysical (LITHOPROBE) and structural data, allow the Sudbury Structure to be interpreted as a multi-ring impact structure. The structure consists of the following lithologies: Sudbury Breccia —dike breccias occurring up to 80 km from the Sudbury Igneous Complex (SIC); Footwall rocks and Footwall Breccia — brecciated, shocked crater floor materials, in part thermally metamorphosed by the overlying SIC; Sublayer and Offset Dikes, Main Mass of the SIC and Basal Member of the Onaping Formation (OF) — geochemically heterogeneous coherent impact melt complex ranging from inclusion-rich basal unit through a dominantly inclusion-free to a capping inclusion-rich impact melt rock; Grey Member of OF — melt-rich impact breccia (suevite); Green Member of OF — thin layer of fall back ejecta; Black Member of OF — reworked and redeposited breccia material; Onwatin and Chelmsford Formations — post-impact sediments. Observational and analytical data support an integrated step-by-step impact model for the genesis of these units. Analysis of the present spatial distribution of various impact-related lithologies and shock metamorphic effects result in an estimated original rim-to-rim diameter of the final crater of 200 or even 280 km for the Sudbury Structure, prior to tectonic thrusting and deformation during the Penokean orogeny.  相似文献   

大别山东段榴辉岩的成分特征及其成因意义   总被引：6，自引：2，他引：6       下载免费PDF全文

葛宁洁  李曙光 《地质学报》1993,67(2):109-122

大别山东段北部和南部榴辉岩的矿物组成和形成的温压条件有明显差异。北部榴辉岩有两种产状:一种产于超基性岩体内,另一种产于片麻岩內;它们均为石榴石-透辉石组合,不含石英,形成温度为600—740℃。南部榴辉岩均产于大别群片麻岩或大理岩中,为石榴石-绿辉石组合,含石英,形成温度为650—800℃。这些差异反映了它们形成环境不同,前者可能是俯冲洋壳在较深部位变质而成,后者可能与俯冲陆壳有关。  相似文献   

The Orogeny in the Altaides     

Qu Guosheng Institute of Geology  State Seismological Bureau  Beijing  He Guoqi 《《地质学报》英文版》1993,67(1)

Studies of the deformation styles, formation types and isotopic age data indicate that the Altaides has successively experienced 5 stages of orogeny: (1) the Kanas orogeny forming the angular unconformity between the Baihaba Formation (O_3) and the Habahe Group (Z-O_2); (2) the Daqiao orogeny (S_3-D_(1-2) giving rise to the early Hercynian quasi-aulacogen extensional continental crust of the area; (3) the Altay orogeny (middle-late Hercynian) leading to the oblique intracontinentai collision and the formation of large shear arc-shaped thrust system and representing a strong orogeny stage; (4) the pan-Altay orogeny (latest Hercynian-Indosinian) resulting in the uplifting and erosion of the mountains as a whole; (5) the Himalayan movement causing the rejuvenation of fault systems and block uplift of the Aitaides since the Cenozoic.  相似文献   

新疆构造运动期序及特征   总被引：6，自引：2，他引：6  

黄河源  朱庆亮 《新疆地质》1993,(4)

新疆地域辽阔,地质构造运动复杂,特征各异。前人曾对新疆构造运动的划分及命名做了大量工作,但多有不一致,有些构造运动的划分或命名依据不足,因此失去了应有的代表性。现根据实际资料,对新疆地质构造运动重新归纳和认识,提出新疆境内构造运动可划分为11期32幕(次),其中前寒武纪6期、古生代2期17幕(次),中新生代3期9幕(次)  相似文献   

晚期海西运动在塔里木盆地北部油气藏形成中的作用   总被引：2，自引：0，他引：2  

康志宏  魏历灵 《新疆地质》1994,(4)

海西晚期，塔里木板块总体为挤压背景。有资料表明，该时期存在两次性质差异较大的构造运动：早二叠世末期和晚二叠世末期构造运动。前期运动以火山活动、海防变迁为特征；后期以沉积构造格局改变、褶皱、断裂活动为特征，并叠置于前期构造之上。晚期海西运动最终定型的古隆起控制了油气聚集指向，形成的古生代坳陷和中新代坳陷控制着油源区展布，造成了众多的、具有捕获油气能力的圈闭类型。断裂和区域性不整合面为油气运移提供了通道，而且对油气再分布及破坏亦有一定影响。  相似文献   

A structural synthesis of the Proterozoic Arabian-Nubian Shield in Egypt   总被引：3，自引：0，他引：3  

R. O. Greiling  M. M. Abdeen  A. A. Dardir  H. El Akhal  M. F. El Ramly  G. M. El Din Kamal  A. F. Osman  A. A. Rashwan  A. H. N. Rice  M. F. Sadek 《International Journal of Earth Sciences》1994,83(3):484-501

Detailed structural geological and related studies were carried out in a number of critical areas in the Proterozoic basement of eastern Egypt to resolve the structural pattern at a regional scale and to assess the general characteristics of tectonic evolution, orogeny and terrane boundaries. Following a brief account of the tectonostratigraphy and timing of the orogenic evolution, the major structural characteristics of the critical areas are presented. Collisional deformation of the terranes ended about 615-600 Ma ago. Subsequent extensional collapse probably occurred within a relatively narrow time span of about 20 Ma (575 – 595 Ma ago) over the Eastern Desert and was followed by a further period of about 50 Ma of late to post-tectonic activity. The regional structures originated mainly during post-collisional events, starting with those related to extensional collapse (molasse basin formation, normal faulting, generation of metamorphic core complexes). Subsequent NNW-SSE shortening is documented by large-scale thrusting (towards the NNW) and folding, distributed over the Eastern Desert, although with variable intensity. Thrusts are overprinted by transpression, which was localized to particular shear zones. Early transpression produced, for example, the Allaqi shear zone and final transpression is documented in the Najd and Wadi Kharit-Wadi Hodein zones. Two terrane boundaries can be defined, the Allaqi and South Hafafit Sutures, which are apparently linked by the high angle sinistral strike-slip Wadi Kharit-Wadi Hodein shear zone with a tectonic transport of about 300 km towards the W/NW. In general, the tectonic evolution shows that extensional collapse is not necessarily the final stage of orogeny, but may be followed by further compressional and transpressional tectonism. The late Pan-African high angle faults were reactivated during Red Sea tectonics both as Riedel shears and normal faults, where they were oriented favourably with respect to the actual stress regime.  相似文献   

Collision orogeny at arc-arc junctions in the Japanese Islands   总被引：1，自引：0，他引：1  

Gaku  Kimura 《Island Arc》1996,5(3):262-275

Abstract In the Japanese Islands, collision tectonics are operating at arc-arc junctions in three regions: Hokkaido, Central Japan and Kyushu. Hokkaido is situated at the junction of the Kuril and Northeast Japan Arcs. The Kuril fore arc sliver collides with the Northeast Japan Arc, and the lower crust of the Kuril Arc thrusts upon the fore arc of the Northeast Japan Arc in Hokkaido. Outcrops of the lower crust are observed in the Hidaka Mountains in the fore arc of the junction area. Central Japan is in the juncture area among the Northeast Japan, Izu-Bonin, and Southwest Japan Arcs. The Izu-Bonin arc is colliding against the Honshu mainland, which has been bent by the collision. Kyushu is a juvenile collision area between the Southwest Japan and Ryukyu Arcs. The fore arc of the Southwest Japan Arc is starting to underthrust beneath the Kyushu islands along the Bungo Strait, where shallow seismicity within the crust is active in terms of the collision. Collision tectonics are observed at most of the arc-arc junctions in the circum-Pacific orogenic belts and may be an important process contributing to the relatively rapid growth of new continental crust in subduction zones.  相似文献   

海南岛后地台造山-造盆模型:火成岩地球化学制约   总被引：9，自引：4，他引：9  

邹和平 《大地构造与成矿学》1997,21(2):117-123

海南岛自海西运动晚幕之后进入后地台活化或地洼阶段，并经历了晚海西-印支期挤压（碰撞）造山、地壳隆起和燕山期以来的块断型造山-造盆作用的过程。火成岩研究资料表明，海南岛地区在晚海西-印支运动期间曾形成一个具有加厚陆壳的后地台造山带；燕山晚期开始出现的裂陷作用是在仍有山根（约60km厚的陆壳）存在的条件下造山带拉伸塌陷阶段的产物；岩石圈底层剥离与地壳山根的去除并最终导致了海南及其邻区从大陆型壳体向陆缘扩张带型壳体的转化。  相似文献   

Gravitational (Rayleigh-Taylor) instability of a layer with non-linear viscosity and convective thinning of continental lithosphere   总被引：8，自引：0，他引：8  

Gregory A. Houseman  Peter Molnar 《Geophysical Journal International》1997,128(1):125-150

  相似文献   

初论陆内造山带的造山模式──以四川龙门山为例   总被引：3，自引：1，他引：3  

林茂炳 《四川地质学报》1996,(3)

四川龙门山造山带是陆内造山带的一个典型实例。陆内造山带经历了漫长的发展演化历史。前寒武纪时期的环境是属于古板块俯冲、碰撞的历史。具活动性大陆边缘性质，岩浆变质作用强烈，构造混杂明显。古生代以来转入地台环境，形成台相沉积。中生代早期转入陆内造山阶段。由早期的褶皱造山进而转化为推覆造山。两类不同性质的造山运动伴随了两类不同性质的前陆沉积盆地的形成和两类不同性质的沉积体系的形成。最终的区域构造特征不同程度地保留了陆内造山各阶段的地质记录，而以最后一次的推覆造山作用的影响最深刻。陆内造山的动力机制是与区域性的板块构造活动的大环境密切相关的。  相似文献