滇西牟定—香格里拉电性剖面及深部构造   总被引：1，自引：0，他引：1       下载免费PDF全文

李文军  邵志刚  闻学泽  王启欣  王根成  张营  蒋长胜  王武星 《地球物理学报》2016,59(1):229-239

通过对滇西NW—SE向牟定—香格里拉大地电磁测深剖面的反演并结合地质构造、小震精定位资料,综合分析了剖面经过地区的深部构造.在滇西北地区深部发育一规模巨大的近水平产出地壳高导层,此高导层从香格里拉一直延伸到永胜盆地以东,沿剖面水平延伸超过200km.地壳高导层又可分为两段,两段高导层在剖面上形成两个香蕉型相连的复合形态,高导层之上的高阻体则形成两个碗型相连的复合结构,碗型内部有向东倾斜的相对低阻带存在.滇西北地区整体构造格架可以解译为一套两个主推覆面构成的叠瓦式推覆系统,两个主推覆面高低起伏形成总长度超过250km的底部滑脱带.第一个主推覆面的长度超过150km,并在丽江东部上翘到接近地表,小金河断裂是其延伸到地表的主要破裂带.第二个主推覆面长度超过120km,过程海断裂后上翘并在永胜以东地区出露地表.根据反向低阻带影像,可以推断推覆体反冲构造发育,在玉龙山至丽江以东和永胜盆地西缘至平川盆地东缘形成两处冲起构造.推覆面在剖面上呈现出平缓-陡峭-再平缓-再陡峭的断坪和断坡相间的阶梯状结构.  相似文献   

An Effective Control System of Thrust and Moment Modulation for a Dynamically Positioned Vessel     

Cho-Chung Liang  Tso-Liang Teng  Wen-Hui Cheng 《Marine Geodesy》2013,36(4):211-227

Dynamic positioning (DP) is an operation method whereby the position of a surface vessel is maintained in close proximity to a required position in the horizontal plane through the controlled application of forces and moments generated by purposely installed thrusters. When estimating thrust, this kind of conventional control system often uses many acceleration sensors, velocity sensors, environment sensors, and filters. Usually, these sensors have measured electrical errors. To reduce the number of sensors used and to decrease the measurement errors, this article presents an effective control system for estimating thrust and moment commands, which is based on energy and impulsemomentum principles. Donha and Brinati's example is followed to verify the feasibility of the present control system, which performs semisubmersible platform positioning using an LQG controller, and the results are feasible and economical. A simulated coring vessel marine positioning in southern Taiwan is presented, which can estimate the counterthrust and moment commands, and the complex environmental forces and moments are described. The results can provide a valuable control system for dynamically positioned vessels.  相似文献   

并联式TBCC发动机排气系统性能数值模拟          下载免费PDF全文

莫建伟  徐惊雷  乔松松 《海洋科学进展》2013,(4):463-469

针对一个并联式涡轮基组合循环(Turbine Based Combined Cycle, TBCC)发动机排气系统的气动方案,对其在整个飞行包线范围内典型工作点上的流场进行了数值模拟研究,获得了飞行包线范围内排气系统相应的推力系数、升力、俯仰力矩随飞行马赫数的变化关系。计算结果显示,在整个飞行包线范围内,排气系统的轴向推力系数随着飞行马赫数先减小后增大,在跨声速飞行时降到最低 Ma=0.9,涡喷不加力时为0.562,加力时0.662),在设计点附近达到最大;升力和俯仰力矩性能在亚声速及跨声速飞行时较差,在超声速飞行时随着飞行马赫数增加逐渐好转。表明排气系统在跨声速飞行范围内工作时应采取措施以改善其性能。   相似文献   

Geomorphic appraisals of active tectonics associated with uplift of the Gohpur–Ganga section in Itanagar, Arunachal Pradesh, India     

R.K. Mrinalinee Devi   《Geomorphology》2008,99(1-4):76-89

The Gohpur–Ganga section is located southwest of Itanagar, India. The study area and its adjacent regions lie between the Main Boundary Thrust (MBT) and the Himalayan Front Fault (HFF) within the Sub-Himalaya of the Eastern Himalaya. The Senkhi stream, draining from the north, passes through the MBT and exhibits local meandering as it approaches the study area. Here, five levels of terraces are observed on the eastern part, whereas only four levels of terraces are observed on the western part. The Senkhi and Dokhoso streams show unpaired terraces consisting of very poorly sorted riverbed materials lacking stratification, indicating tectonic activity during deposition. Crude imbrications are also observed on the terrace deposits. A wind gap from an earlier active channel is observed at latitude 27°04′42.4″ N and longitude 93°35′22.4″ E at the height of about 35 m from the present active channel of Senkhi stream. Linear arrangements of ponds trending northeast–southwest on the western side of the study section may represent the paleochannel of Dokhoso stream meeting the Senkhi stream abruptly through this gap earlier. Major lineament trends are observed along NNE–SSW, NE–SW and ENE–WSW direction. The Gohpur–Ganga section is on Quaternary deposits, resting over the Siwaliks with angular contact. Climatic changes of Pleistocene–Holocene times seem to have affected the sedimentation pattern of this part of the Sub-Himalaya, in association with proximal tectonism associated with active tectonic activities, which uplifted the Quaternary deposits. Older and younger terrace deposits seem to mark the Pleistocene–Holocene boundary in the study area with the older terraces showing a well-oxidized and semi-consolidated nature compared to the unoxidized nature of the younger terraces.  相似文献   

The Monagas Fold-Thrust Belt of Eastern Venezuela. Part I: Structural and thermal modeling     

Marien Parra  Gilberto J. Sánchez 《Marine and Petroleum Geology》2011,28(1):40-69

The Eastern Venezuelan Basin (EVB) contains one of the largest hydrocarbon accumulations in the world. Main petroleum targets are buried structures of the Monagas Fold-Thrust Belt (MFTB) which forms the northeastern edge of the EVB. The objective of this study is to integrate the seismic and well data that has been acquired over the last 10 years across the MFTB and EVB, to create an updated structural model. Three regional cross sections 60-75 km long are presented across an area of 4000 km².Five structural domains are described: Amarilis, Furrial, Jusepín, Cotoperí and Pirital. They are characterized by thrusts and high-angle reverse faults. Structural style changes along strike are related to variations in depth of detachment levels and to the strike-slip component of the deformation. We have estimated a shortening between 43 and 59 km that increases eastward over a distance of 40 km.The evolution of the MFTB is divided in four episodes based on stratigraphic, structural and thermal maturity evidences: (1) Oligocene-early Miocene initial movement of Pirital thrust. (2) Early Miocene simultaneous movement on Pirital, Furrial and Cotoperí thrusts. (3) Middle Miocene increases in velocity and change in geometry of Pirital thrust, during an out of sequence period of thrusting. (4) Late Miocene to Holocene minor thrust activity. This evolution is consistent with the oblique convergence between the Caribbean and South American plates and the convergence between North and South America that affected Eastern Venezuela during the Cenozoic.By analyzing the along-strike variations in structural style, new exploratory opportunities have been identified. Under the Orocual and Santa Bárbara fields two untested duplex structures are proposed; they were developed during the middle Miocene. Other prospective hydrocarbon traps are associated to oblique transpressive faults that create anticline structures.  相似文献   

InSAR analysis of a blind thrust rupture and related active folding: the 1999 Ain Temouchent earthquake (M w 5.7, Algeria) case study     

Samir Belabbès  Mustapha Meghraoui  Ziyadin Çakir  Youcef Bouhadad 《Journal of Seismology》2009,13(4):421-432

We study the surface deformation associated with the 22 December 1999 earthquake, a moderate sized but damaging event at Ain Temouchent (northwestern Algeria) using Interferometric Satellite Aperture Radar images (InSAR). The mainshock focal mechanism solution indicates reverse faulting with a NE–SW trending rupture comparable to other major seismic events of this section of the Africa–Eurasia plate boundary. Previously, the earthquake fault parameters were, however, poorly known because no aftershocks were precisely determined and no coseismic surface ruptures were observed in the field. Using a pair of ERS data with small baseline and short temporal separation in the ascending orbit we obtained an interferogram that shows the coseismic surface displacement field despite poor coherence. The interferogram measures four fringes and displays an ellipse-shaped lobe with ∼11 cm peak line-of-sight displacement. The elastic modeling using a boundary element method (Poly3Dinv) indicate coseismic slip reaching up to 1 m at 5 km depth on the N 57° E trending, dipping 32° NW Tafna thrust fault. The geodetic estimate of seismic moment is 4.7 × 10¹⁷ N m. (Mw 5.7) in is good agreement with seismological results. The elliptical shape of the surface displacement field coincides with the NE–SW trending Berdani fault-related fold. The consistency between the geological observations and InSAR solution shed light on the precise earthquake location and related Tafna fault parameters.  相似文献   

Transition from frontal accretion to underplating in a part of the Nankai Trough Accretionary Complex off Shikoku (SW Japan) and extensional features on the lower trench slope     

Jeremy Leggett  Yutaka Aoki  Takefumi Toba 《Marine and Petroleum Geology》1985,2(2):131-141

Migrated multichannel seismic reflection profiles and bathymetry from a 200 × 120 km area of the Nankai Trough inner slope reveal three physiographic-tectonic domains on the lowermost slope. Linear ridges demarking laterally-continuous hangingwall anticlines above ramps in a relatively simple imbricate stack of trench turbidites characterize the western domain. An imbricate fan underlies a relatively flat structural terrace in the east. Between these two domains lies a compound knoll (Minami Muroto Knoll) some 40 km long, opposite which the thrust front pushes some 10 km further seaward than is the case in the domains to east and west. In the western ‘linear-ridge’ domain previous DSDP drilling penetrated turbiditic trench fill uplifted in the lowermost thrust-fold terrace above a decollement within the underthrusting Shikoku Basin (oceanic plate) sequence. The Shikoku Basin sequence in the western domain is divided into an upper, poorly reflective, hemipelagic claystone unit and a lower, strongly reflective, unit comprising Pliocene turbidites. The lower unit is traceable intact up to c.20 km landward below the lower trench slope and in the better resolved profiles the decollement lies along the base of the claystone unit. A similar decollement within the Shikoku Basin sequence in the eastern domain is traceable up to c.22 km landward. A critical seismic record crossing the western part of Minami-Muroto Knoll shows that the decollement is traceable only 8 km landward to a point, under the steep slope at the front of the knoll, landward of which the subducting Shikoku basin sequence is apparently thickened by as much as twice. This thickening, occuring as it does immediately along-strike from a simple imbricate fan to the east of the knoll and a relatively simple imbricate stack to the west (both evidently involving no strata from the lower Shikoku Basin unit) we ascribe to underplating by formation of duplexes of Shikoku Basin strata. Strike-parallel extension, akin to that postulated for high structural levels in certain thrust belts, is caused by uplift of the knoll as a result either of the underplating, or segmentation of the subducting oceanic crust, or both: a normal fault throws to the west off the west flank of the knoll. It bounds a transverse, trough-like, slope-basin with at least 900 m of fill. Upslope from the knoll broadly slope-parallel normal faults cut, and pond, recent slope sediments. The most impressive is a listric growth fault which dips trenchward. Alternative explanations for these involve extensional collapse of this part of the prism resulting from the subduction of a topographic high, or a zone of selective underplating below the trenchward portion of Minami Murato Knoll.  相似文献   

辽宁西部八家子多金属矿田控矿构造型式     

陈荣度  苏传玉 《国土资源》1991,(4)

本文分析了八家子多金属矿田的地质构造特征,提出该区的构造型式为一个滑脱—逆冲推覆构造。它是在北西问南东方向的侧向挤压作用下,由八家子附近的中上元古界与古生界地质块体,沿着与基底花岗岩的界面自北西向南东滑移造成的。主要表现特征是:在前缘形成了呈铲式的收缩型滑脱断层、逆冲断层等挤压性构造,在后缘则出现张裂带并陷落成盆地,两侧发育具有转换断层性质的走滑断层。逆冲断层及边界走精断层是区内主要控矿构造。八家子滑脱—逆冲推覆构造的主要活动时期为三叠纪晚期,结束于早侏罗世。  相似文献   

造山带与前陆盆地结构构造及动力学研究思路和进展   总被引：5，自引：0，他引：5  

董云鹏  张国伟 《地球科学进展》1997,(1)

运用大量的研究成果，综合分析了大陆岩石圈结构和动力学特征，在此基础上探讨了造山带研究的思路和方法，总结了造山带结构、构造及其形成演化研究的新进展。指出前陆盆地的研究是深入研究造山带的关键，前陆盆地是前陆冲断作用引起岩石圈挠曲变形的结果，阐述了前陆盆地形成机制的研究进展  相似文献   

Fabric controls on strain accommodation in naturally deformed mylonites: The influence of interconnected micaceous layers     

《Journal of Structural Geology》2016

We present microstructural analyses demonstrating how the geometrical distribution and interconnectivity of mica influences quartz crystallographic preferred orientation (CPO) development in naturally deformed rocks. We use a polymineralic (Qtz + Pl + Kfs + Bt + Ms ± Grt ± Tur) mylonite from the Zanskar Shear Zone, a section of the South Tibetan Detachment (NW Himalaya), to demonstrate how quartz CPO intensity decreases from quartz-dominated domains to micaceous domains, independently of whether or not quartz grains are pinned by mica grains. We then use a bimineralic (Qtz + Ms) mylonite from the Main Central Thrust (NW Himalaya) to show how increasing mica grain connectivity is concomitant with a systematic weakening of quartz CPO. Our results draw distinctions between CPO weakening due to: (i) second phase drag, leading to ineffective recovery in quartz; and (ii) increased transmission and localisation of strain between interconnected mica grains. In the latter case, well-connected micaceous layers take up most of the strain, weakening the rock and preventing straining of the stronger quartz matrix. Our findings suggest that rock weakening in quartz-rich crustal rocks is influenced not only by the presence of mica-rich layers but also the degree of mica grain connectivity, which allows for more effective strain localization through the entire rock mass.  相似文献