The Fault Block''s Framework in Boli Basin and its Control Over the Deposition     

Cao Chengrun  SHAN Xuanlong  Wang Dongpo  WANG Xianmin  Yao Ping 《世界地质(英文版)》2001,4(1)

Boli basin, between Yishu fracture belt and Dunmi fracture belt, is the biggest Mesozoic coal basin in the east of Heilongjiang Province. Now it is a fault - fold remnant basin. The basin' s shape is generally consistent with the whole distribution of the cover folds, an arc protruding southwards. The basement of the basin can be divided into three fault blocks or structural units. The formation and evoluation of the basin in Mesozoic was determined by the basement fault blocks' displacement features rusulted from by the movement of the edge faults and the main basement faults.  相似文献   

安徽巢湖大型平卧褶皱研究   总被引：3，自引：0，他引：3  

张开均  施央申 《大地构造与成矿学》1993,17(2):179-189

巢湖平卧褶皱由一个背斜和一个向斜组成,枢纽呈NNE向,轴面微向NWW平卧背斜根部倾斜。卷入褶皱的地层为上震旦统至上三叠统,厚达3.1km。褶皱分布面积约380km~2,波长9km,波幅18km。后期直立褶皱叠加于平卧褶皱之上,褶皱缩短量达19.17km,缩短率约53.7％,褶皱受控于大玵台阶状滑脱断层。褶皱地层由NWW往SEE运动,是一种变动滑脱褶皱。  相似文献   

The Migif–Hafafit gneissic complex of the Egyptian Eastern Desert: fold interference patterns involving multiply deformed sheath folds     

Abdel-Rahman Fowler  Baher El Kalioubi 《Tectonophysics》2002,346(3-4)

The Wadi Hafafit Complex (WHC) is an arcuate belt of orthogneisses, migmatites and other high-grade metamorphic rocks, which marks the boundary between the Central Eastern and the South Eastern Deserts of Egypt. In the WHC, gneissic meta-gabbro outlines macroscopic fold interference patterns characterized by elliptical to irregular culminations cored by gneissic meta-tonalite to meta-trondhjemite. The five main culminations of the WHC have previously been labeled A (most northerly), B, C, D and E (most southerly). A detailed structural investigation of B, C, D and E reveals that these structures are a result of the interference of four macroscopic fold phases, the first three of which may represent a single deformation event. The first folding involved sheath-like fold nappes, which were transported to the N or NW, assisted by translation on gently dipping mylonite zones. The regional gneissosity and mineral extension lineations formed during this folding event. The fold nappes were deformed by mainly open upright small macroscopic and mesocopic folds with approximately NE-trending hinges. As a probable continuation of the latter folding, the sheaths were buckled into large macroscopic folds and monoclines with the same NE-trends. The fourth macroscopic folding resulted from shortening along the NE–SW direction, producing mainly NW–SE-trending upright gently plunging folds. Gravitative uplift is disputed as a component of the deformation history of the WHC. The peculiarities of the fold interference pattern result from the interesting behaviour of sheath folds during their refolding.  相似文献   

Is there any detachment in the Lower Dolpo (western Nepal)?Y a-t-il un détachement dans le bas Dolpo (Népal occidental) ?     

Rodolfo Carosi  Chiara Montomoli  Dario Visonà 《Comptes Rendus Geoscience》2002,334(12):933-940

A structural transect in the Lower Dolpo highlights that the deformation and metamorphism of the Tibetan Zone (TZ) increase toward the bottom of the sequence. The contact with the underlying HHC is marked by a metamorphic jump from amphibolite facies in the carbonatic rocks of the upper part of the HHC to greenschist facies marbles in the TZ. Moreover, the HHC and the TZ show different metamorphic histories. The contact zone shows a strain increase accompanied by asymmetric folds with a top-to-the-northeast vergence, connected to a down-to-the-northeast tectonic transport. The contact is interpreted as an extensional shear zone, connected to the South Tibetan Detachment System. To cite this article: R. Carosi et al., C. R. Geoscience 334 (2002) 933–940.  相似文献   

岳西菖蒲地区超高压变质带内的构造地层序列与叠加褶皱型式     

钱存超  汤加富  高天山 《大地构造与成矿学》2003,27(3):212-221

以大别造山带南部菖蒲地区为解剖区,结合区域地质调查分析,建立了包括浅变质岩层、超高压变质岩片在内的构造地层序列—岩片组合。对其组成特征、界面性质、形成时代、变形序列等,进行了较系统阐明,并对叠加褶皱型式及形成机制进行了讨论。  相似文献   

Curvature analysis of triangulated surfaces in structural geology   总被引：6，自引：0，他引：6  

Philippe Samson  Jean-Laurent Mallet 《Mathematical Geology》1997,29(3):391-412

This paper addresses the problem of characterizing the shape of a geological surface on the basis of its principal curvatures. The surface is assumed to be modeled as a set of adjacent triangles defined by the location of their vertices and a method is proposed for estimating numerically the principal curvatures at the vertices of the triangles using a local C² interpolant. Also shown is how principal curvatures can be useful for studying the deformation of a geological surface (with application to 3D balanced unfolding), and analyzing the folding or faulting of the interface between two adjacent layers.  相似文献   

冀东迁安铁矿区早前寒武纪硅铁岩矿层褶皱变形序列     

顾德林  李志忠 《现代地质》1990,4(3):60-69

文中根据硅铁矿层的褶皱形态、复合关系等确定迁安铁矿区在中元古代之前发生过6期褶皱变形,叙述了这6期褶皱的特征和分布,讨论了褶皱的成因。区内各期褶皱形态演化规律反映了变形过程中岩石塑性有规律递减的特点。这一演化规律对研究早前寒武纪地区褶皱变形和指导该区找矿工作有重要意义。  相似文献   

Reappraisal of the structure of the Western Iron Ore Group, Singhbhum craton, eastern India: Implications for the exploration of BIF-hosted iron ore deposits   总被引：1，自引：0，他引：1  

Gautam Ghosh  Joydip Mukhopadhyay 《Gondwana Research》2007,12(4):525-532

The middle to late Archean Iron Ore Group rocks occurring along the western margin (the Western Iron Ore basin) of the Singhbhum Granite massif in the Singhbhum craton were deformed during Iron Ore orogeny and are disposed in a horseshoe-shaped synclinal structure in the eastern part of the Indian shield. The Western Iron Ore basin hosts almost all the major high-grade iron ore deposits of eastern India. Contrary to the established view, present analysis emphasizes that the horseshoe fold in reality is a synclinorium consisting of a syncline–anticline fold pair which were later cross-folded along an east–west axis.

Structural analysis in the eastern anticline of the ‘horseshoe synclinorium’ suggests that the BIF hosting the high-grade iron ore bodies are disposed in three linear NNE–SSW trending belts, each showing an open synclinal geometry. Later cross folding produced development of widespread dome and basin pattern at the sub-horizontal hinge zones of these synclinal fold belts. The major iron ore deposits in the eastern anticline at the present level of erosion are preferentially localized within shallow elongated basinal structures only. The axis of the adjoining western syncline was similarly uplifted as partial culminations where cross-folded against E–W anticlinal axes. But here, the BIF-iron ore bodies are preferentially localized within elongated domal structures in contrast to the basinal sites in the adjacent eastern anticline. Such an inference based on structural analysis could probably be utilized as a potential tool for all future explorations, reserve estimation and recovery of the iron ore deposits in the terrain.  相似文献   

Late Paleozoic and Mesozoic deformations in the southwestern Primorye region     

V. P. Utkin  P. L. Nevolin  A. N. Mitrokhin 《Russian Journal of Pacific Geology》2007,1(4):307-323

Two types of tectonic deformations indicating different geodynamic settings are defined in the southwestern Primorye region. Near-latitudinal compression forces were responsible for the oldest, Late Paleozoic deformations. The Permian stratified complexes host a near-meridional system of folds and zones of dynamothermal metamorphism, cleavage, and foliation oriented orthogonally relative to the compression. Late Proterozoic (?) mafic-ultramafic rocks are characterized by similar deformations. In the Late Permian, the deformations were accompanied by granitoid magmatism controlled by fold and cleavage structures. The younger, Mesozoic deformations produced by near-meridional compression are represented by NE-trending sinistral strike-slip faults and their structural parageneses: an ENE-trending system of folds and downdip-thrusts both superimposed on Paleozoic protostructures and manifested in Mesozoic and Cenozoic sequences. It is inferred that, at the Paleozoic-Mesozoic boundary, near-latitudinal compression was replaced by near-meridional compression, probably, in response to the corresponding change in direction of the lateral displacement of the interacting Asian continent and (or) Pacific Plate.  相似文献   

Cenozoic folding in the Cumuruxatiba basin,Brazil: An approach to the deformation trigger by the Abrolhos magmatism     

《Marine and Petroleum Geology》2014

The Cumuruxatiba basin is located in the central portion of the eastern Brazilian margin surrounded by Cenozoic magmatic highs that belong to the Abrolhos Magmatic Complex. This basin was formed by rifting, in the Neocomian followed by thermal subsidence during late Cretaceous like other basins along the Eastern Brazilian margin. In the Cenozoic, the Abrolhos magmatism took place as sills and dykes intruded the sedimentary section, primarily during the Paleogene. In that time, there was a strong NS contractional deformation in the basin represented by folds related to reverse faults coeval with Abrolhos magmatism activity. The structural restorations of regional 2D seismic sections revealed that most of the contractional deformation was concentrated at the beginning of the Cenozoic with maximum peak at the Eocene (up to 33% of total shortening and rate of 6 km/Ma). The Post-Eocene period was marked by a decrease in the strain rate that continues to the present day (around 4 km/Ma to less than 1). 3D structural modelling exhibited a major, well-developed E–W to NE–SW fold belt that accommodated most of the contractional Cenozoic deformation between Royal Charlotte and Sulphur Minerva magmatic highs. Volcanic eruptions and magmatic flows from the Abrolhos complex resulted in differential overburden on edge of the basin, acting as a trigger for halokinesis and the subsequent formation of fault-related folds. In general, such structures were developed close to adjacent magmatic highs, commonly exhibiting vergence towards the centre of the basin. Some magmatic features formed coeval with Cenozoic syn-deformation sediments clearly indicate that Abrolhos magmatism activity and contractional deformation development were associated. The study of the thickness variation of the syn-deformation section in relation to fault-related folds on deformation maps and maximum strain diagrams revealed that most folds were activated and re-activated several times during the Cenozoic without a systematic kinematic pattern. This lack of systematic deformation might be related to the variation of the magmatic pulse activity of adjacent magmatic highs resulting in a complex interference pattern of Cenozoic folds. These structural interpretations of the timing of fault-related folds that are potential Cenozoic traps in the Cumuruxatiba basin play a fundamental role in petroleum systems and exploration of low-risk hydrocarbon prospects.  相似文献