New data on the evolution of the Tan–Lu fault belt: constraints from geological–geophysical surveys in the southern segment     

《International Geology Review》2012,54(13):1562-1578

The Tan–Lu fault is a well-known active fault belt in eastern China that has been the focus of geologic studies over the past 40 years. Since the late 1990s, numerous geophysical and geological investigations of this dislocation zone have been carried out by Chinese oil companies, as well as by universities. However, its deep structure, active periods of slip, and fault mechanism remain obscure. This study focuses on the deep structures within the Jiashan–Lujiang segment of the Tan–Lu fault belt, using high-precision geophysical tools, including magnetotelluric and magnetic sounding, and artificial seismic exploration using active source methods. Our results suggest that this segment is composed of several sub-faults. The southern part of the Tan–Lu fault belt, along the Jiashan–Lujiang sub-fault, can be divided into two parts on the basis of contrasting geological features. The Chihe–Taihu sub-fault is taken as the boundary between the two. The region east of the Chihe–Taihu sub-fault is dominated by strike–slip activity along several sub-faults. Only the Jiashan–Lujiang sub-fault is exposed at the surface, forming a large, positive flower structure, the result of late Middle Jurassic to early Late Jurassic strike–slip movement along the dislocation zone. Three sub-faults are present in Dingyuan County, two of which disappear in the southern Hefei Basin. Only the Chihe–Taihu sub-fault extends to the eastern edge of this basin, creating a half-graben depression that formed during the Early Cretaceous. Our results indicate that the present-day deep structure of the southern portion of the Tan–Lu fault zone is the result of a combination of strike–slip and extensional tectonics.  相似文献   

Controls on large‐scale patterns of fluvial sandbody distribution in alluvial to coastal plain strata: Upper Cretaceous Blackhawk Formation,Wasatch Plateau,Central Utah,USA     

GARY J. HAMPSON  M. ROYHAN GANI  HIRANYA SAHOO  ANDREAS RITTERSBACHER  ANDREW RANSON  JOHN A. HOWELL  SIMON J. BUCKLEY  BRYAN BRACKEN 《Sedimentology》2012,59(7):2226-2258

Current models of alluvial to coastal plain stratigraphy are concept‐driven and focus on relative sea‐level as an allogenic control. These models are tested herein using data from a large (ca 100 km long and 300 m thick), continuous outcrop belt (Upper Cretaceous Blackhawk Formation, central Utah, USA). Many channelized fluvial sandbodies in the Blackhawk Formation have a multilateral and multistorey internal character, and they generally increase in size and abundance (from ca 10% to ca 30% of the strata) from base to top of the formation. These regional, low‐resolution trends exhibit much local variation, but are interpreted to reflect progressively decreasing tectonic subsidence in the upper Blackhawk Formation and overlying Castlegate Sandstone. The trend may also incorporate progressively more frequent channel avulsion during deposition of the lower Blackhawk Formation. Laterally extensive coal zones formed on the coastal plain during shallow‐marine transgressions, and define the high‐resolution stratigraphic framework of the lower Blackhawk Formation. Large (up to 25 m thick and 1 to 6 km wide), multistorey, multilateral, fluvial channel‐complex sandbodies that overlie composite erosion surfaces occur at distinct stratigraphic levels, and are interpreted as fluvial incised valley fills. Low amplitude (<30 m) relative sea‐level variations are interpreted as the dominant control on stratigraphic architecture in the lower Blackhawk Formation, which was deposited up to 50 km inland from the coeval shoreline. In contrast, the high‐resolution stratigraphy of the upper Blackhawk Formation is poorly defined, and channelized fluvial sandbodies are poorly organized. Vertical and laterally offset stacking of a small proportion (<10%) of sandbodies produced ‘clusters’ that are not confined by ‘master’ erosion surfaces. Avulsion is interpreted to dominate the stratigraphic architecture of the upper Blackhawk Formation. This data‐driven analysis indicates that alluvial to coastal plain stratigraphic architecture reflects a combination of various allogenic controls and autogenic behaviours. The relative sea‐level control emphasized in sequence stratigraphic models is only rarely dominant.  相似文献   

岷江上游水系对龙门山断裂带右旋走滑作用的响应   总被引：1，自引：0，他引：1  

陈浩  李勇 《山地学报》2013,31(2):211-217

汶川8.0级特大地震是岷江上游流域最新一次区域构造活动,在此次地震中,岷江河道因北川-映秀断裂北西盘的右旋走滑作用而被水平错动0.8±0.2 m,岷江河道南西方向的河流阶地也被同步位错0.6±0.1 m。切过龙门山主干断裂的岷江上游干、支流水系因若干次历史地震驱动的走滑作用而发生同步弯曲。根据水系水平扭错量和岷江干、支流初始形成时间计算可知,穿越岷江支流河道的汶川-茂县断裂右旋走滑速率为1～1.4 mm/a,切过岷江干流河道的北川-映秀断裂和彭县-灌县断裂右旋滑动速率分别为0.94 mm/a和0.71 mm/a。计算结果表明,龙门山各主干断裂右旋走滑作用有自北西向南东减弱的趋势。  相似文献   

Determinable and non-determinable parameters of galvanic distortion in magnetotellurics   总被引：3，自引：0，他引：3  

H. M. Bibby  T. G. Caldwell  C. Brown 《Geophysical Journal International》2005,163(3):915-930

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高瓦斯面顶板走向钻孔抽放数值模拟与试验     

邓明  张国枢  刘泽功  秦汝祥 《煤田地质与勘探》2008,36(5)

高瓦斯矿井"U"型通风工作面采空区上隅角容易积聚瓦斯。以渗流理论为基础,根据气体扩散定律和质量守恒定律,建立了顶板走向钻孔抽放采空区瓦斯流场数学模型,并用6点隐式有限差分法进行了求解。以VB6.0为平台,利用工程软件SURFER模拟了抽放钻孔周围瓦斯压力场,并在现场进行了工业试验。理论研究与现场实践均表明:顶板走向钻孔抽放采空区瓦斯是解决高瓦斯工作面上隅角瓦斯积聚的一种行之有效的措施;顶板裂隙程度和状态是影响瓦斯抽放量的主要因素,将钻孔布置在适当的裂隙带中,瓦斯抽放浓度可达30%～90%,抽放负压可达50～55 kPa;数值模拟方法研究采空区瓦斯运移等工程实际问题是可行的。  相似文献   

西藏扎西康铅锌银矿床含矿走滑断裂地球物理特征及找矿方向          下载免费PDF全文

焦彦杰  梁生贤  郭镜  张伟  廖国忠 《地质找矿论丛》2016,31(3):434-439

扎西康铅锌银矿床位于北喜马拉雅大陆边缘褶冲带内,是西藏扎西康整装勘查区中大型铅锌锑银共生矿床之一。矿床赋存于下侏罗统日当组,容矿岩石为含碳钙质板岩、钙质板岩和构造角砾岩,矿体严格受近SN向和NE向断裂控制,呈脉状、透镜状产出。通过岩石物性分析,认为矿体具有中低电阻和中低极化的物性特征。在矿集区开展了音频大地电磁法(AMT)和激发极化法试验,结合地质地球物理初始模型,从地质背景、勘查模型角度分析,含矿走滑断裂的围岩具有中低极化率、断裂走向与极化率条带一致的特征;认为在中低极化率区域存在断裂,且断裂走向的垂直方向存在高极化、低电阻区,赋矿可能性较大。  相似文献   

Mesozoic and Cenozoic structural deformation in the NW Tarim Basin,China: a case study of the Piqiang–Selibuya Fault     

Yong Yang  Wen-Qian Yao  Jia-Jia Yan  Ying Guo  Da-Qing Xie 《International Geology Review》2018,60(7):929-943

The Piqiang–Selibuya Fault is the most significant fault in the NW Tarim Basin, China. It has attracted increasing attention because of the discovery of a series of oil (gas) fields in and around the fault zone. The structural characteristics and evolution of the Piqiang–Selibuya Fault remain controversial. Field geological surveys and seismic data interpretation reveal that the fault has experienced three stages of activity. The thicknesses of the Permian and Miocene strata on opposing sides of the fault are clearly different, and these reveal that the fault has experienced two stages of significant thrusting. The first stage took place at the end of the Triassic and was associated with the Qiangtang Block amalgamated to the south margin of Eurasia. The second stage occurred at the end of the Miocene and might have been caused by the northwards overthrusting of the Pamir. These two stages of thrusting led to the lower–middle Cambrian detachment layer in the eastern part of the Keping thrust belt being 2 km shallower than in the western part. Since the Pliocene, the southern Tien Shan orogenic belt has been reactivated and thrust towards the interior of the Tarim Basin, and a series of ENE–WSW-trending thrust sheets have formed in the Keping thrust belt. Because of the different depth of the detachment layer on the opposing sides of the Piqiang–Selibuya Fault, the number and spacing of thrust sheets formed to the east of the fault differ from those to the west. This dissimilar deformation led to the strike–slip displacement on the Piqiang–Selibuya Fault. The three stages of fault activity record three important tectonic events in the NW Tarim Basin. Qualitative analysis of this activity helps us better understand the influence of the far-field effect of the collisions that occurred on the southern margin of the Eurasia plate on the structural deformation of the NW Tarim Basin.  相似文献   

我国西南地区斑岩矿床与走滑断裂关系及其勘查意义     

秦建华 《地质与勘探》2010,46(6):1028-1035

我国西南地区是我国重要的斑岩矿床勘查开发基地,自20世纪60年代以来,相继勘查发现了玉龙、驱龙、普朗、多不杂等特大型斑岩铜矿。初步研究表明,西南地区斑岩矿床的集聚与走滑断裂存在着密切的空间关系。认识并深入研究斑岩矿床与走滑断裂存在着的这种关系,对于斑岩矿床勘查具有重要的意义。在西南地区现有的5个斑岩成矿带开展斑岩矿床勘查时,在沿区域性走滑断裂方向勘查并加强对走滑断层带内或其周围派生的局部引张或挤压地区开展找矿的同时,还应注意开展对鲜水河-小江左旋走滑断裂带及两侧斑岩矿床的勘查。  相似文献   

雪峰山西麓中生代盆地属性及构造意义   总被引：6，自引：0，他引：6  

张进  马宗晋  杨健  陈必河  雷永良  王宗秀  李涛 《地质学报》2010,84(5):631-650

雪峰山西侧发育一系列的中生代盆地,它们的形成与后期变形是华南地区晚三叠世以来板内变形的响应。晚三叠世-早、中侏罗世,雪峰山地区由于桃江-安化-溆浦断裂的左行压剪作用,在雪峰山西北侧形成早期沅麻前陆盆地,而在雪峰山中南段由于走滑作用形成拉分盆地,雪峰山西侧印支期并不存在统一的前陆盆地,其印支期造山规模很有限,为陆内造山。从白垩纪开始,雪峰山西麓盆地进入不同的构造体制环境,总体上经历了三期主要的盆地形成和改造事件。白垩纪早期沅麻盆地进入区域伸展阶段,该期的盆地并不是前人认为的前陆盆地,古水流表明物源为东西两侧的雪峰山和武陵山,而中期沅麻盆地继承早期的伸展体制,生长地层、地堑、地垒结构发育,古水流指示物源依旧是两侧山地,该期伸展可能与整个华南同期的伸展一样受控于同样的机制。进入新生代,雪峰山西麓盆地经历了两期重要的变形改造阶段,早期由于桃江-安化-溆浦的右行走滑,产生了北东向的主压应力,在沅麻盆地中产生了北东走向的张节理,这些节理在后期往往发育成正断层,造成这期变形的原因是由于55～25Ma之间,印度-欧亚板块的碰撞在整个东亚地区产生的一系列右行走滑断裂所致。新生代后期变形体现在北西—南东向挤压,在沅麻盆地以及天柱盆地东缘形成了一系列的逆冲构造,古生界以及元古界逆冲于中生界之上,这期挤压在盆地中形成了稳定分布的一组共轭节理。这期变形与整个东部中新世变形可能有同一的构造背景,其原因与太平洋板块的俯冲无关,而与菲律宾海板块于中新世左右由南向北运移并与华南大陆碰撞有关。  相似文献   

金管冲铀矿床控矿构造特征分析   总被引：2，自引：0，他引：2  

陈小东  李建威  傅昭仁  李紫金 《铀矿地质》2001,17(5):273-279

金管冲铀矿床位于湘东地区丫江桥黑云母二长花岗岩体接触带。通过成矿构造背景和矿床构造研究，本文系统论述了不同级虽构造对铀成矿的 控制作用，认为NNE向走滑断裂与铀成矿作用之间具有密切的成因联系。晚三叠世－侏罗纪时期的构造会聚走滑导致剪切重熔型花岗岩－丫江桥岩体的形成和成矿元素的富集。白垩纪－第三纪的构造离散走滑在矿区及其附近形成张扭性断裂和离散走滑盆地，这些断裂和盆地为成矿流体的运移、循环及成矿物质的沉淀提供了良好的构造场所。  相似文献