Investigation on influence factors of dual laterologs curve form

In order to investigate the influences of caliper, formation thickness and invaded zone on the form of dual laterologs, forward modeling technique were applied to calculate the dual laterologs for different cases. The result shows that the resistivity logs become smoother and lower as the borehole diameter increases, the increase of the contrast between mud resistivity and formation resistivity induce the logs to be more pointed. When the formation thickness is less than 1m, the two-peak on the logs for resistive invasion vanished, and for thickness between 1 m and 4 m, the form of logs does not vary significantly. If the formation thickness is greater than 4 m, a platform appears on the logs at the middle of the formation. The thinner the invaded zone is, the more obvious the invasion feature on the laterologs is. For thick invaded zone the form of logs tend to be that of an uninvaded resistive formation. The form and amplitude of logs depend on the resistivity contrast between invaded zone, uninvaded formation and adjacentlayers.     

Effective seed distribution pattern of an upward shift species in alpine tundra of Changbai Mountains

The vegetation of alpine tundra in the Changbai Mountains has experienced great changes in recent decades. Narrowleaf small reed(Deyeuxia angustifolia), a perennial herb from the birch forest zone had crossed the tree line and invaded into the alpine tundra zone. To reveal the driven mechanism of D. angustifolia invasion, there is an urgent need to figure out the effective seed distribution pattern, which could tell us where the potential risk regions are and help us to interpret the invasion process. In this study, we focus on the locations of the seeds in the soil layer and mean to characterize the effective seed distribution pattern of D. angustifolia. The relationship between the environmental variables and the effective seed distribution pattern was also assessed by redundancy analysis. Results showed that seeds of D. angustifolia spread in the alpine tundra with a considerable number(mean value of 322 per m2). They were mainly distributed in the low elevation areas with no significant differences in different slope positions. Effective seed number(ESN) occurrences of D. angustifolia were different in various plant communities. Plant communities with lower canopy cover tended to have more seeds of D. angustifolia. Our research indicated reliable quantitative information on the extent to which habitats are susceptible to invasion.     

Revision of P-wave velocity and thickness of hydrate layer in Shenhu Area,South China Sea

To revise P-wave velocity and thickness of the hydrate layer in the Shenhu area of the South China Sea, acoustic and resistivity logging curves are reanalyzed. The waterlogging phenomenon is found in the shallow sediments of five drilling wells, which causes P-wave velocity to approximate the propagation velocity of sea water(about 1500 m s-1). This also affects the identification of the hydrate layer and results in the underestimate of its thickness. In addition, because there could be about a 5 m thick velocity ramp above or below the hydrate layer as interpreted by acoustic and resistivity logging curves, the recalibrated thickness of this layer is less than the original estimated thickness. The recalibrated P-wave velocity of the hydrate layer is also higher than the original estimated velocity. For the drilling well with a relatively thin hydrate layer, the velocity ramp plays a more important role in identifying and determining the thickness of the layer.     

Comparative Assessment of Tundra Vegetation Changes Between North and Southwest Slopes of Changbai Mountains,China, in Response to Global Warming

Vegetation in high altitude areas normally exhibits the strongest response to global warming. We investigated the tundra vegetation on the Changbai Mountains and revealed the similarities and differences between the north and the southwest slopes of the Changbai Mountains in response to global warming. Our results were as follows: 1) The average temperatures in the growing season have increased from 1981 to 2015, the climate tendency rate was 0.38℃/10 yr, and there was no obvious change in precipitation observed. 2) The tundra vegetation of the Changbai Mountains has changed significantly over the last 30 years. Specifically, herbaceous plants have invaded into the tundra zone, and the proportion of herbaceous plants was larger than that of shrubs. Shrub tundra was transforming into shrub-grass tundra. 3) The tundra vegetation in the north and southwest slopes of the Changbai Mountains responded differently to global warming. The southwest slope showed a significantly higher degree of invasion from herbaceous plants and exhibited greater vegetation change than the north slope. 4) The species diversity of plant communities on the tundra zone of the north slope changed unimodally with altitude, while that on the tundra zone of the southwest slope decreased monotonously with altitude. Differences in the degree of invasion from herbaceous plants resulted in differences in species diversity patterns between the north and southwest slopes. Differences in local microclimate, plant community successional stage and soil fertility resulted in differential responses of tundra vegetation to global warming.     

Applications of variogram modeling to electrical resistivity data for the occurrence and distribution of saline groundwater in Domail Plain,northwestern Himalayan fold and thrust belt,Pakistan

This paper studies electrical resistivity dataset acquired for a groundwater study in the Domail Plain in the northwestern Himalayan section of Pakistan. Through a combination of geostatistical analysis, geophysical inversion and visualization techniques, it is possible to re-model and visualize the single dimension resistivity data into 2D and 3D space. The variogram models are utilized to extend the interpretation of the data and to distinguish individual lithologic units and the occurrence of saline water within the subsurface. The resistivity data has been calibrated with the lithological logs taken from the available boreholes. As such the alluvial system of the Domail Plain has formed during episodes of local tectonic activity with fluvial erosion and deposition yielding coarse sediments with high electrical resistivities near to the mountain ranges and finer sediments with medium to low electrical resistivities which tend to settle in the basin center. Thus a change is depositional setting happened from basin lacustrine environment to flash flooding during the Himalayan orogeny. The occurrence of rock salt in the northern mountains has imparted a great influence on the groundwater quality of the study area. The salt is dissolved by water which infiltrates into the subsurface through the water channels. Variogram aided gridding of resistivity data helps to identify the occurrence and distribution of saline water in the subsurface.     

铧厂沟金矿床北部控矿剪切带地质特征及金的富集规律

野外调研和室内分析结果表明。区域韧性剪切带在铧厂沟金矿床非常发育，并经历了右行—左行—右行多期（次）活动。北部控矿韧脆性剪切带是区域韧性剪切带演化的产物，以左行剪切为主。位于铁夹树—庙湾北部厚层灰岩的下部。北部金矿带受北部控矿剪切带控制，长度大于1km．厚度约70cm，从地表延伸至1120m标高。未见尖灭趋势。黄铁矿是该类矿石中最重要的金属矿物。自然金是主要金矿物。有明金和显微金两种。矿石结构构造较为复杂。集中反映了热液矿床的构造特征。矿带的形成可划分为热液期和表生期。原生矿石中绝大部分明金、显微金中的包体金和裂隙金都与黄铁矿密切相关。黄铁矿（Ⅰ）经历了韧脆性变形。因而是金的最佳载体矿物。北部韧脆性剪切带的多期（次）活动，使金富集成为工业矿体。结合地质特征，预测该矿带可延伸至1120m以下一定深度。     

临沂市柳航头地区地热资源特征研究

区域地质调查和地热地质勘探资料显示,临沂市柳航头地区区域构造发育较强烈,大气降水通过构造破碎带向地下深部运动,深部寒武-奥陶纪灰岩岩溶地层厚度可达1 500余米。区域地下水在深部渗透性较好的岩溶地层内径流,向柳航头地区运动过程中,不断受到地球深部热源的地温加热而形成地热水,寒武-奥陶纪岩溶地层成为热储层,其上覆地层导热率较低,是较好的盖层。结合研究区内的地热井深部测温数据和地热水化学特征数据,建立柳航头地区地热概念模型。     

高密度电法在某公路路基下隐伏岩溶探测中的应用

灰岩分布区易发生岩溶塌陷等地质灾害,高密度电阻率法是岩溶地质调查的重要手段。以某一段穿越岩溶发育区的公路为例,应用高密度电法对区内暗河、槽谷型岩溶塘、落水洞等灾害地质体进行了探测,结果显示拟建路段覆盖层厚度大约为2~20 m,基岩内岩溶极发育,岩石地表起伏大,溶沟、溶槽、岩溶塌陷、落水洞发育;岩石中溶蚀裂隙、溶洞发育。表明高密度电阻率法能够有效地判定岩溶的发育情况,可以为地质灾害评估提供科学客观的依据。     

高密度电法在老山隧道勘察中的应用

应用高密度电阻率法勘察宁淮高速公路南京老山隧道工程,查明了隧道YK5 280~ZK5 540段的地层分布和构造特征,并推断出鹰嘴山断层的位置和产状,结合勘察资料证明该断层为高角度逆断层。预测出隧道和断层破碎带相交处为浅部裂隙岩溶含水带中的优良导水带,该处涌水的可能性很大,其推断结果在施工中得到证实。说明高密度电法是进行隧道勘察和构造裂隙岩溶富水带探测的一种可靠手段。     

GEOTECTONICS CHARACTERISTICS AND THEIR RELATION WITH GAS-OIL POOL FORMATION OF THE DONGSHA FAULT-UP LIFTED MASSIF

The Dongsha fault- uplifted massif (for convenience . Dongsha massif from here on) is located in the northern continental shelf-slope of the South China Sea, where the water depth is 100-400m. The massif is considered to be a part of the large-scale fault-uplifted zone directed NE and separating the Pearl River Mouth Basin into northern and southern graben areas. The sedimentary cover of the Pearl River Mouth Graben consists mainly of a 7000-10000m thick Tertiary system. A large-scale uplift occurred in the Dongsha fault-uplifted zone during Paleocene-Eocene when the lower structural layer (lower Tertiary) existed only in the small depressions of the fault-uplifted zone. The formation and evolution of the Dongsha fault-uplifted zone could be divided into: 1) the basement formation stage (J2-K1); 2) the slowly uplifted stage (K2-E22); 3) the weathering and erosion stage (E23-E31); 4) the integrated subsidence stage (E32-N12) and 5) the last uplifted stage (N13-Q). The formation of the oil and gas pools o     

Effects of nitrogen deposition on tundra vegetation undergoing invasion by Deyeuxia angustifolia in Changbai Mountains

In recent years, herbaceous species such as Deyeuxia angustifolia(Kom.) Y. L. Chang has invaded alpine tundra regions of the western slope of the Changbai Mountains. Because atmospheric nitrogen deposition is predicted to increase under a warming climate and D. angustifolia is sensitive to nitrogen addition, field experiments were conducted from 2010 to 2013 to determine the effect of increased nitrogen deposition on the mechanisms of D. angustifolia invasion. The goal of this study is to evaluate the impact of increased nitrogen deposition on the changes in alpine tundra vegetation(consisting mostly of Rhododendron chrysanthum Pall. and Vaccinium uliginosum Linn.). The results showed that: 1) simulated nitrogen deposition affected overall characteristics and structure of R. chrysanthum and V. uliginosum communities and had a positive impact on the growth of tundra vegetation invaded by D. angustifolia; 2) R. chrysanthum was more resistant to invasion by D. angustifolia than V. uliginosum; 3) simulated nitrogen deposition could improve the growth and enhance the competitiveness of D. angustifolia, which was gradually replacing R. chrysanthum and V. uliginosum and might become the dominant species in the system in future, transforming alpine tundra into alpine meadow in the Changbai Mountains.     

高密度电阻率法在平阴县岩溶地质灾害调查中的应用

平阴县地处泰山山脉西延余脉与鲁西平原的过渡地带,地势南高北低,中部隆起,属浅切割构造剥蚀低山丘陵区。其县城及周边岩溶较发育,给当地居民住宅及生产生活造成一定影响。为查明岩溶地质灾害塌陷等造成的不良影响,利用高密度电阻率法圈定地下岩溶、溶洞等不良地质体的分布范围及第四系的大致厚度,应用效果较好。     

新疆尼勒克县喀英迪地区铅锌矿地质特征及成因

喀英迪铅锌矿主要产于早石炭世阿克沙克组及其与晚奥陶世呼独克达坂组的接触带上。通过普查工作共圈定15个铅锌矿体。其中主要矿体4个,Ⅰ-4矿体处于晚奥陶世呼独克达坂组灰岩与早石炭世阿克沙克组的不整合接触面上及其两侧,工程控制总长度为523m,最大斜深100m。倾向70°～100°,倾角一般20°～50°,连续性较好。该矿体铅单工程厚0.86～5.64m,平均2.86m,厚度变化系数为70.57%;锌单工程厚0.80～5.64m,平均1.81m,厚度变化系数为93.97%,属于变化较稳定型矿体。铅单工程品位0.62%～16.47%,平均4.53%,品位变化系数114.34%;锌单工程品位0.53%～12.37%,平均3.78%,品位变化系数57.47%。属于有用组分分布较均匀型矿体。通过对矿床地质特征的研究,认为该矿床属沉积岩容矿的、层控的、构造控制非岩浆型低温热液矿床。     

贵州六盘水水城矿区小牛煤矿钻孔中断层发育特征分析

利用钻探岩心识别断裂形变、挤压扭曲、岩心破碎带等断层标志, 有利于勘探区构造地质条件的分析。通过对钻孔岩心岩性特征、地层厚度、煤层间距等方面的研究,发现ZK13钻孔在C51与C52煤层之间地层出现明显的揉皱与破碎现象、地层厚度与煤层间距增大,同时测井曲线显示地层有重复现象,推测在C51与C52煤层之间发育一逆断层;C54与C58煤层之间地层也比较破碎、地层厚度与煤层间距减小,伽玛伽玛曲线幅值增大,推测在C54与C58煤层之间发育一正断层。     

辽宁省海水入侵成因及防治措施

海水入侵是在自然和人为因素综合作用下形成的地质灾害。辽宁省海水入侵自 70年代以来呈逐渐增加趋势 ,具有入侵面积广、发展速度快等特点。目前海水入侵已成为我国较为突出的地质灾害 ,给工农业生产和人民生活造成很大危害。针对海水入侵形成机制及危害程度的地域性 ,目前已采取不同的防治措施 ,如控制开采 ,人工回灌 ,修建地下水库等 ,取得一定效果。     

断—盖时空匹配及其对油气聚集与分布的控制作用——以南堡凹陷中浅层东营组为例

为研究南堡凹陷中浅层东营组油气分布规律,根据油气输导断裂与盖层时空匹配与油气分布之间的关系,分析油气聚集与分布的控制作用.结果表明:南堡凹陷中浅层断—盖空间匹配关系对油气分布层位的控制作用表现:(1)如果东营组二段泥岩盖层有效厚度大于90～95m,无论馆陶组三段火山岩盖层有效厚度多大,则油气主要分布在东三、四段(简称东二段、馆三段);(2)如果东二段火山岩盖层有效厚度小于90～95m,馆三段火山岩盖层有效厚度大于130～150m,则油气除分布在东三、四段外,还可以分布在东一段和馆四段;(3)如果东三段泥岩盖层有效厚度小于90～95m,馆三段火山岩盖层有效厚度小于130～150m,明下段泥岩盖层有效厚度大于90～95m时,则油气从下至上均有分布.3套区域性盖层封闭能力形成时期早于断裂输导油气的大量时期,可有效封住断裂输导运移来的油气,这是导致3套区域性盖层之下油气相对富集的重要原因.     

日照市海岸带古河道分布特征研究

根据收集到的日照市海岸带浅地层剖面测量调查资料,把多条浅地层剖面中出露的古河道断面推测性地连接起来,重建了以往的古河道体系,综合分析了日照市海岸带古河道的分布特征。日照近海区域存在一个主干河道呈SW-NE走向的梳状河道网,古河道形成于距今约4.4万a的末次冰期。古河道的形成是河流的侵蚀、搬运、沉积及后期的海平面上升、潮汐改造等多种因素共同作用的结果。在末次冰期,研究区内气候湿润,河流流速较大,河流搬运泥沙的能力较强,长期侵蚀作用形成下切古河道,在古河道中容易形成淤积较多河流携带的砂体。古河道断面形态主要呈U形、V形、W形、箱形和倒梯形。主干河道北西侧,分支河道较密,南东侧分支河道较稀疏。主河道长约40km,横截面由南西向北东逐渐变宽,最宽处达4km。分支河道多数以NW向为主,少数为NE向,长度介于8~20km之间,宽度约为1~3km。古河道主要位于16~24m水深的闭合深度以外区域,对其中的砂体经过粒度筛选可作为将来进行人工抛沙的砂源。     

Application of high-frequency magnetotelluric method in porphyry copper deposit exploration: a case study of Duobaoshan deposit area

The Duobaoshan mine area in Heilongjiang is located in the northeast section of Xingmeng orogenic belt and is in the west side of Hegang Mountain-Heihe fault zone .There exist many deposits in this area , and its metallogenic conditions are superior , which has been one of the hotspots in geological prospecting and metal -logenic research in Northeast China .On the basis of previous studies , the authors used the EH-4 electromagnet-ic imaging system to carry out the data acquisition of three survey lines in Woduhe Village , Duobaoshan Town , Nenjiang County .Through the analysis of apparent resistivity section under TE and TM polarization modes , in-tegrating regional geological data , it is concluded that:①the electrical characteristics of the metal ore in this area show a relatively low resistance , and according to its resistivity difference with surrounding rocks , the geo-metrical structures and apparent resistivity parameters of the low resistivity bodies in the lower section of the sur -vey line are defined , and the electrical anomalies can be identified;②faults F1 and F2 may have a good metal-logenic environment , so they are recommended for further exploration;③low resistance metal ore bodies have good correlation with local small structures or faults , which may play an iconic role for the delineation of key target areas;④in the process of using apparent resistivity to define the geometric structures of ore bodies un -derground , comprehensive analysis integrating the advantages of TE and TM models should be carry out to achieve more reliable inversion results .     

辽北凡河坳拉谷及其对铅-锌矿的控制作用

辽北地区中,上元古宙凡河群,据其总的构造样式;近万 m 厚的沉积—火山建造;厚度巨大的细碧岩及其与硅质岩、英安岩、凝灰岩和火山角砾岩组合;非补偿性和补偿性堆积的双层结构;平行裂陷槽延伸方向的生长性断裂和重力梯级带,以及拉伸角砾岩带、滑塌构造、碳酸盐岩的浊积岩系等,表明凡河群为中、晚元古宙分布于华北地台北缘的坳拉谷沉积。其形成作用可据 Ramberg(1972)的重力不稳定模式来阐明。该坳拉谷构造作用的早期阶段控制了关门山铅—锌矿田的成矿和分布。对该坳拉谷构造及成矿作用的研究无疑对关门山矿田新一轮找矿和靶区分析是有稗益的,同时对整个华北地台北缘构造演化研究也具有一定意义。     

Formation mechanism of freshwater zone around the Meimao Sandbank in the Changjiang estuary

This study focuses on dynamic mechanism behind the formation of the freshwater zone around the Meimao Sandbank by use of 3D numerical simulation. The Meimao Sandbank is located along the southern bank of the South Passage in the Changjiang (Yangtze River) estuary, which is considered as a freshwater resource for Shanghai City. Interaction between runoff and tide is the main mechanism of the freshwater zone formation. However, the freshwater zone often suffers from saltwater intrusion in dry season. Tidal oscillation is stronger during spring tides, able to carry freshwater farther seaward. Therefore, it is more likely to occur during the ebb of a spring tide in dry seasons. In addition, the water zone is sensitive to runoff: when runoff decreases, it disappears, and vice versa. The northerly winds favor the formation of the freshwater zone.