3-D shear wave velocity structure in the shallow crust of the Tan-Lu fault zone in Lujiang,Anhui,and adjacent areas,and its tectonic implications

The Tan-Lu fault zone is a large NNE-trending fault zone in eastern China.Investigations of the structures of the fault zone and its surrounding areas have attracted much attention.In this study,we used dense-array ambient noise tomography to construct a threedimensional shear wave velocity model of shallow crust in an area about 80km×70km in Lujiang,Anhui Province,eastern China.For approximately one month we collected continuous ambient noise signals recorded by 90 short-period seismographs in the region,and obtained the short-period Rayleigh wave empirical Green's functions between stations by the cross-correlation method;we also extracted 0.5–8 s fundamental mode Rayleigh wave group velocity and phase velocity dispersion curves.Based on the direct surface wave tomography method,we jointly inverted the group velocity and phase velocity dispersion data of all paths and obtained the 3-D shear wave velocity structure in the depth range of 0–5 km.The results revealed important geological structural features of the study area.In the north region,the sedimentary center of the Hefei Basin—the southwestern part of the Chaohu Lake—shows a significant low-velocity anomaly to a depth of at least 5 km.The southwestern and southeastern regions of the array are the eastern margin of the Dabie orogenic belt and the intrusion area of Luzong volcanic rocks,respectively,and both show obvious high-speed anomalies;the sedimentary area within the Tan-Lu fault zone(about 10 km wide)shows low-velocity anomalies.However,the volcanic rock intrusion area in the fault zone is shown as high velocity.Our shallow crustal imaging results reflect the characteristics of different structures in the study area,especially the high-speed intrusive rocks in the Tan-Lu fault zone,which were probably partially derived from the magmatic activity of Luzong volcanic basin.From the Late Cretaceous to Early Tertiary,the Tan-Lu fault zone was in a period of extensional activity;the special stress environment and the fractured fault zone morphology provided conditions for magma in the Luzong volcanic basin to intrude into the Tan-Lu fault zone in the west.Our 3-D model can also provide important information for deep resource exploration and earthquake strong ground motion simulation.

Deep- Seated Tectonic Activation of Tancheng-Lujiang Fault Zone and Its Control over Jiaodong Gold Concentrated Region, China

A comprehensive discussion on the deep seated genesis of gold metallogenic materials and the tectono magmatic controls over gold deposits is given in this paper, which is based on the crustal and upper mantle structural characteristics of the Jiaodong massif, the property, activation history and styles of the Tancheng Lujiang fault zone, as well as a series of accompanying tectono magmatic events. Prediction for further prospecting gold deposits in the area is also made.

The Formation and Evolution of the Lujiang-Zongyang Volcano-Structural Depression in Anhui and Its Relation to Mineralization

The Lujiang-Zongyang volcano-structural depression resulted from the combined action of tectonism and volcanism. Its evolution progressed through five stages from 190 to 105 Ma B.P., during which nine types of metal and pyrite deposits were formed. These deposits show obvious regularities in the temporal-spatial distribution and have certain genetic relation, forming a minerogenetic series related to shoshonite within or around the volcano-structural depression on the basement that sank for a long period of time. This paper suggests a four-dimensional model of the formation and evolution of a typical volcano-structural depression and its related mineralizalion in a transition belt from the active margins to the inner part of a plate under alternating shear-compressive and shear-extensional stress conditions, but predominantly shear-extensional stress conditions.

The Geothermal Study of the Mid-Segment of the Tancheng-Lujiang Fault Zone and Its Neighboring Region

In this paper,25 new terrestrial heat flow values newly observed along the mid-segment of the Tancheng-Lujiang fault zone are listed.With these geothermal data and 37 other terrestrial heat flow values(previously published),we describe the distribution features of terrestrial heat flows in the area.In this research,the two-dimensional temperature structure from the surface to lithospheric bottom of the Huaibei-Sixian-Jinhu profile is inferred by using the finite-element method and the temperature and heat flow of sedimentary,granitic,and basaltic layers is calculated.

Geological Evidence and Characteristics of Activity of the Wuhe-Mingguang Section of Tancheng-Lujiang Fault Zone in Late Pleistocene

As the most influential strike-slip fault in East China,the Tancheng-Lujiang fault zone draws scholars attention for its strong seismic activity. Nevertheless,most research has been conducted along segments in Shandong Province and Bohai Bay where huge earthquakes occur frequently. Meanwhile,it is generally believed that segments lying to the south of Huaihe River have been inactive since the late Quaternary and thus it is incapable of generating moderate or strong earthquakes. However,these understandings about the Tancheng-Lujiang fault have been questioned by our recent work for part of the fault south to the Huaihe River. Based on interpretation of high-resolution satellite images,detailed field investigations near Wuhe county and Mingguang City in northern Anhui Province and elaborate microstructure analysis, we come to the conclusion that the Tancheng-Lujiang fault zone mainly consists of four branches and at least one should be active since the late Pleistocene for the Wuhe-Mingguang section. This segment is monopolized by dextral strike-slip motion in late Quaternary. Different from obvious faults in bed rocks or consolidated sediments,the latest activity trace in Quaternary loose sediment revealed by trench excavation is not obvious or even invisible to visual observation. According to our recent work and previous studies, we call for more attention to be paid to invisible faults in young sediment and also suggest that more research be conducted along this seemingly placid segment.

Characteristic Analysis of Anomalies of Strong Earthquakes along the Tancheng-Lujiang Fault Zone and Both Its Sides

This article made a systematic statistical analysis on the duration,spatial distribution,form,range,type and reliability of precursory anomalies based on the observations of precursors of 24 moderate-strong earthquakes occurring along the Tancheng-Lujiang fault zone and its bilateral areas in Shandong,Liaoning,Hebei,Jiangsu and Jiangxi Provinces in the period from 1966 to 2005. Results show that:( 1) For M7. 0 and M6. 0earthquakes,med-term abnormities are the greatest in number,short-term abnormities come second,and imminent anomalies are the least. For M5. 0 earthquakes,short-term abnormities are often the most in number,imminent anomalies come second,and the med-term ones are the least.( 2) Precursory anomalies are periodical,part of the med and short-term anomalies are shown as short-term and imminent anomalies during their development.( 3) The development of precursor shows quasi-synchronism; the closer to earthquake occurrence time,the more turning changes of anomalies will appear.( 4)Anomalies mainly occur within an epicenter distance of 100 km, showing a relative concentrated distribution in space,and the shorter the distance to epicenter,the higher the anomaly station / item rate.( 5) The spatial distribution of anomalies is relatively correlated to the strike of structures,having a good consistency with the structure.( 6)There is no significant correlation between duration of abnormities and the epicenter distance.( 7) The higher the magnitude of the earthquake,the greater the amplitude of the abnormities measured with the same observation approach.( 8) In terms of the itemsof the observations,fluid abnormities are the greatest in number,followed by deformation and electromagnetism observations.( 9) For all observation items,med and short-term abnormities make up the majority and short-term and imminent anomalies the minority.( 10) In fluid,deformation and electromagnetism observations,fairly reliable anomalies are about double the number of reliable anomalies.

Motion and Deformation State of the Tancheng-Lujiang Fault Zone Derived from GPS Data

Based on the rotation in the entire block and homogeneous strain model ( REHSM) ,we firstly analyze the motion and deformation features across the southern part of Tancheng- Lujiang fault zone from GPS velocity fields in period of 1999 ～ 2001,2001 ～ 2004,2004 ～ 2007 and 2007 ～ 2009. The results show a dextral strike-slip feature in the Weifang- Tancheng segment and sinistral strike-slip in the Tancheng-Lujiang segment. And the deformation perpendicular to the Tancheng-Lujiang fault zone alternates between tension and compression in different time-intervals. Then we resolve the relative rigid motion of blocks around Bohai Bay to the Circum-Bohai Sea area by deducting the entire rigid motion of the Circum-Bohai Sea area. We find that the Yanshan-Bohai seismic belt split this area into two parts,the northern part moving NW,and the other SE.

Prehistoric Earthquakes in the Chishan Segment of the Tancheng-Lujiang Fault Zone during the Mid-Late Pleistocene

Chishan is located in Sixian County of Anhui Province, and the west branch fault of Tancheng-Lujiang fault zone passes through here. According to previous research, the Chishan segment of Tancheng-Lujiang fault zone has been obviously active since the Quaternary. Trenches excavated perpendicular to the Chishan segment for this study have revealed many prehistoric earthquake ruins-the multi-phase reverse faulting colluvial wedge, which is represented as the western brick-red sandstone of the late Cretaceous or maize gravel stratum of the mid Pleistocene of the hanging wall of the fault overlapping eastward the mid-late Pleistocene brown clay. In the base of the wedges, steep NW-dipping faults were found, and the steep fault planes turned upward to gently dipping collapse planes. As revealed by the trenches, the connection line of the breaking points strikes NNE in general. Heaving landforms are preserved at most parts of the tailing edge of the hanging wall where the fault passes through, and some EW-trending gullies were offset by right-lateral faulting. The two walls of several trenches have consistently shown that the collapse of traces have been pushed by a west-to-east force. Among them, Tc1~Tc4 show that the brick red limestone(K2)overthrust and collapsed on the yellow-brown clay containing ferro-manganese nodules (Q2-3P); Tc5 reveals that the yellowish-white gravel (Q2P) and the sandstone (K2) and overthrust and collapsed on the aforementioned clay. Reverse faulting colluvial wedges are found on both walls of each of the 8 trenches, but the number of wedges revealed in different trenches is different: there is 1 wedge, and 2 wedges in Tc1 and Tc3. 3 wedges in Tc2, Tc4 and Tc5, and in individual trenches, few wedges are revealed. This may be related to the trench’s location, depth and height of the remaining denudation. From the analysis of the trenches and the thermoluminescence dating results, we can preliminarily conclude that multiple large-scale reverse faulting stick events have taken place on the Chishan segment of the Tancheng-Lujiang fault zone during the mid-late Pleistocene, that is to say, many pre-historic strong earthquakes have occurred.

New Evidence of Late Quaternary Activity on the Xinyi-Wuhe Segment of the Tancheng-Lujiang Fault Zone

The Tancheng-Lujiang fault zone has great influence in eastern China. Studies have shown obvious signs of neotectonic activities on the Xinyi-Wuhe segment of the Tancheng-Lujiang fault zone. In this study,on the basis of the previous work,many seismological surveys are made along the Tancheng-Lujiang fault zone and trenches are excavated in key sites.Combined with the analysis of the seismic activities along the fault,the fault movement features and future seismic risk are discussed. Much first-hand information obtained in the paper can provide an important reference value for the study of large earthquake recurrence rules and the mid and long-term earthquake prediction on the Xinyi-Wuhe segment of the Tancheng-Lujiang fault zone.

INDUSTRIAL ACCUMULATION OF MANTLE SOURCE HELIUM AND THE TANCHENGLUJIANG FRACTURE ZONE

Helium abundance in the air is only 5.3 x 10-6. 3He forms as universe-nuclear is synthesized. 4He is the result of α-decay of some radioactive isotopes, such as 235U, 238U and 252Th. There are three kinds of helium sources in the earth, that is, meteoric helium, mantle source helium and crust source helium. Their distinguishing sign depends on 3He/4He value.

A stony meteorite fallen in Lujiang, Anhui Province

A stony meteorite fell in Lujiang County, Anhui Province. Its falling, minerals, chon-drules, shock metamorphism and oxidation are simply revealed. The meteorite is composed of olivine, bronzite, diopside, clinoenstatite, plagioclase, muscovite, phlogopite, whit-lockite, ka-macite, taenite, troilite, chromite, ilmenite and oxides of iron. Based on its characteristics of mineralogical chemistry and petrology, the chemical rock type of the meteorite is LL6.

音频大地电磁测深法在深部地热构造勘查中的应用

为探测江苏泗洪县柳山湖景区的深部地热构造,搜集已有的地质地球物理资料和已知勘探钻孔资料,布置了14条音频大地电磁测深(AMT)测线,通过资料采集、预处理、反演,得到了研究区2000 m以浅地质体电阻率空间分布情况。勘探结果表明:研究区存在较好的低阻分布带,且连续性好,推测发育两条深部构造断裂带f_(1)和f_(2),其中f_(2)断裂带规模较大,破碎带中含水,而断裂带上部为完整-较完整的高阻层,可能是良好的盖层。因此,推测深部断裂破碎带f_(2)可能是良好的含水和储水通道,建议在构造带低阻异常中心位置重点研究,为下一步钻孔布设提供依据。

安徽庐江方言语气词研究

研究根据语法意义的不同,将庐江方言语气词分为三类:事态语气词、情态语气词与疑问语气词。庐江方言语气词特色鲜明,有四大特点:数量总体多于普通话,十分丰富;用于陈述句的语气词少于普通话中用于陈述句的语气词,说明庐江人民不常用平调表达感情,易采用有变化的升调或降调传递语气;语气词和语气之间并不是一一对应的,同一语气可以用不同语气词来表示,不同语气可以用同一语气词表示,具有很大的灵活性;语气词与其所在的江淮官话区保持较高的相似性,但是部分语气词较为独特,表现出相对的独立性。研究考察了部分庐江方言语气词来源,并指出了其语法化路径。

长江中下游成矿带庐枞矿集区花岗岩型铀矿床成矿作用研究进展

安徽庐枞矿集区是长江中下游成矿带重要的多金属矿集区,也是华南铀成矿省内重要的花岗岩型铀矿成矿区,系统开展铀矿床成矿作用和成矿规律研究,对于完善区域成矿理论、指导铀矿找矿勘探具有基础性意义。庐枞矿集区铀矿床主要分布在庐枞火山岩盆地东南侧的A型花岗岩带上,但近年深部探测科学钻孔揭示火山岩盆地内隐伏正长岩中也存在铀矿化线索。与A型花岗岩有关的铀矿床呈NE向分布,矿体产出于石英正长岩与围岩接触带,受到侵入接触构造、断裂构造及层间构造的控制,具有典型热液充填成矿的特征,成矿年龄集中在114~108 Ma;赋矿岩体为多期次侵位的复式岩体,主体年龄为127~123 Ma,末阶段碱性长石花岗岩株年龄为115~110 Ma,岩石属于A1型花岗岩,形成于伸展的构造背景下;成矿物质主要来源于赋矿岩体及围岩地层,成矿流体具有深循环大气降水与岩浆流体混合的特征。火山岩盆地内的铀矿化产出于火山岩盖层之下的隐伏正长岩中,具有热液充填成矿的特点,成矿年龄为131~129 Ma;赋矿正长岩成岩年龄为131 Ma,属于橄榄安粗质岩石,形成于挤压向拉张转换的构造背景下;岩浆阶段末期分异的高温富B、F的富铀热液在开放体系下沉淀成矿。盆地内隐伏正长岩中的铀矿化为矿集区中高温铀矿化的代表,与A型花岗岩有关的铀矿床则为晚期中低温铀矿化。综合来看,产铀岩体判别标志、精确的铀成矿年龄以及幔源物质与铀成矿之间的关系应是本区未来研究的重要方向。

基于乡村振兴示范区建设的云南潞江镇传统村落振兴路径研究

传统村落是见证乡村人居环境演变规律的遗产宝库,潜藏着传统营造智慧和生计策略,是中华农耕文明和民族文化传承的精神家园。边疆少数民族地区的传统村落是推进乡村振兴建设的前沿阵地,探索其振兴路径成为新时期的重点任务。研究以潞江镇老城和坪河传统村落为对象,通过漫步叙事方法,以居民简述视角开展传统村落资源禀赋识别,从场所、村域、区域三个尺度解析资源特征和发展问题。基于乡村振兴示范区建设背景,提出以多民族共建共荣共享为主线、以民族文化传承与保护为核心、以自然资源共生与转化为途径、以区域内三产共生共融为骨架和以构建点到点联动机制为经脉的“人村境业制”传统村落乡村振兴路径,同时,基于不同尺度挖掘和识别民族文化、自然景观和人文资源特征,探索传统村落融合联动发展的途径。

灌区弃渣场设计及稳定性分析研究:以潞江灌区工程为例

弃渣场稳定运行在水利工程施工过程中至关重要。高速公路、水利水电枢纽、灌区等生产建设项目,在建设过程中大量开挖的岩土体在工程回填中往往存在较大的冗余,这将导致在工程建设时通常会产生大量废弃无用渣土,弃渣场中堆积的工程弃渣结构松散,极易因环境因素或自重因素等发生滑动失稳,可能引发严重地质灾害。结合灌区工程特点,对弃渣场设计考量因素及弃渣堆积体稳定性分析进行研究,通过摩根斯顿-普赖斯法,对潞江灌区工程涉及弃渣场的边坡稳定和挡渣墙的抗滑、抗倾覆及地基承载力稳定安全系数进行计算,以保证弃渣场在工程建设中的稳定安全,服务于潞江灌区工程水土保持工作,为同类工程弃渣场的规划设计及施工维护提供经验对比和设计参考。

全域旅游高质量发展路径研究——以庐江县为例

全域旅游是区域旅游发展的一种高级状态,也是解决区域发展不均衡、不充分问题的重要方式,符合高质量发展的要求。结构优化、要素升级、制度变革是高质量发展的三大动能,为高质量发展提供动力源泉。高质量发展时代,更加要求全域旅游注重地域景观环境营造、公共服务提升、基础设施完善和个人消费服务升级。文章剖析庐江全域旅游高质量发展问题,构建旅游高质量发展的实现路径,解析庐江县全域旅游发展实践,进而提出丰富全域产品体系、优化治理体系、构建旅游目的地品牌形象、完善旅游集散及智慧体系、打造串联全域的旅游廊道、彰显旅游服务品质、共创主客共享共治等优化实施路径,以助力其高质量发展。

郯庐断裂带江苏段山左口−泗洪断裂活动特征变化及成因分析

山左口−泗洪断裂经历了郯庐断裂带整个演化阶段,该断裂的最新活动时代具有分段性。确定该断裂的活动性分段位置及原因对研究郯庐断裂带内各分支断裂的活动性变化具有重要的参考价值。因此,利用野外地质调查、浅层地震勘探以及钻孔联合地质剖面等深浅部相结合的立体式研究方法,对山左口−泗洪断裂的活动性进行了研究。结果表明:山左口−泗洪断裂在北马陵山东侧为晚更新世活动断裂,在新沂市为中更新世断裂。新沂市嶂仓村小学新发现一条晚更新世−全新世早期活动断裂,该断裂可将山左口−泗洪断裂分为南北两段,北段为晚更新世活动断裂,南段为早中更新世断裂,北段晚更新世以来活动量向南调整至嶂仓村小学断裂带。北马陵山为郯庐断裂带内部沿断裂走向展布的基岩山体,其第四纪以来的持续抬升与山左口−泗洪断裂的活动性变化有一定的耦合关系。该研究对认识郯庐断裂带其他分支断裂的活动性变化和丘陵山脉的形成机制具有重要的参考价值。

庐江地区不同栽培方式对油菜产量及经济效益的影响

为探索庐江地区不同栽培方式对油菜产量与经济效益的影响,在相同茬口条件下,以陕油28为试验材料,研究人工育苗移栽、联合机条播和无人机撒播这3种栽培方式对油菜生育特性、产量构成因素及经济效益等的影响。结果表明,3种栽培方式同时播种,出苗基本一致,但抽薹期、初花期、盛花期和终花期人工育苗移栽较联合机条播和无人机撒播推迟7~15 d,成熟期推迟5~7 d,全生育期亦延长6~8 d。人工育苗移栽油菜产量最高,联合机条播经济效益最好,亦是目前农户主要栽培方式。