Emplacement Ages and Geochemical Characteristics of Grabbroic Intrusions and Prospecting Orientation of Related Deposit in Luodian,Guizhou Province

Emplacement ages, geochemical characteristics and analysis of continental dynamics on gabbroic intrusions in Luodian County, Guizhou Province, have been discussed based on studies of isotopic chronology （the whole-rock Sm-Nd and Rb-Sr isochron methods）, major elements, trace elements and PGE. Intrusive activities of the gabbroic intrusions in the study area took place during the Late Yanshanian Orogenic Movement （the Cretaceous Period）, as indicated by the Sm-Nd isochron ages （t）=（99.6±4.5） （2σ） Ma and by the Rb-Sr isochron ages t=（97±1.6） （2σ） Ma. The gabbroic intrusions are attached to mafic rocks in cal-alkaline basaltic series. They occurred as dikes and might be formed under an extensional background of the continent. Differentiation of their magmatic crystallization resulted in obvious zonation of petrography. In the gabbroic intrusions of this study, large ion lithophile elements and LREE are enriched, and the chondrite-normalized REE distribution pattern is leftward inclined without anomalies of JCe or JEu, and there are high concentrations of PGE and ratios of Pd/Ir （averaging 4.21）. All of these imply that their source areas may be basaltic magma in the upper mantle with high-level partial melting, derived from EMl-type enriched mantle. It is different from Emeishan basalt, which may be related to the upper mantle at low-grade partial melting. Emplacement mechanism of the gabbroic intrusions in this study may suppose to be asthenosphere upheaving as an isolated hot wave in the presence of mantle fluid, resulting in basaltic magma intruded into the continental crust as a diapiric intrusion. Therefore, uplifting of faulting-block and extensional deformation could take place in the shallow part of the continental crust while vertical amassing and accretion of magmatic materials in the deep part of the continental crust. These special processes could supposed to be a special background of continental dynamics for this large-scale epithermal metallogenic domain, such as Au, As, Sb and Hg deposits, and vertical uplifting of the Yunnan-Guizhou Plateau in the Cretaceous Period.

Discriminating characters of ore-forming intrusions in the super-large Chalukou porphyry Mo deposit,NE China

The Chalukou porphyry Mo deposit, located in the Great Hinggan Range, is the largest Mo deposit in northeast China, although the age and genesis of the associated magmatic intrusions remain debated.Here we report zircon U-Pb ages and trace elements, whole rock geochemistry and Sre Nd isotope data with a view to understand the relationship between the magmatism and molybdenum mineralization.Zircon U-Pb analysis yield an age of 475 Ma for rhyolite in the older strata, 168 Ma for the premineralization monzogranite, and 154 Ma for the syn-mineralization granite porphyry. The granite porphyry and quartz porphyry are considered as the ore-forming intrusions. These rocks are peraluminous, alkali-calcic, and belong to high-K to shoshonitic series with a strong depletion of Eu. They also display characteristics of I-type granites. The rocks exhibit wide variations of(87 Sr/86 Sr)iin the range of 0.705426 -0.707363, and ε_(Nd)(t) of -3.7 to 0.93. Zircon REE distribution patterns show characteristics between crust and the mantle, implying magma genesis through crust-mantle interaction. The Fe_2O_3/FeO values(average 1) for the whole rock and EuN/Eu*Nvalues(average 0.45), Ce^(4+)/Ce^(3+) values(average 301)for zircon grains from the granite porphyry are higher than those from other lithologies. These features suggest that the ore-forming intrusions(syn-mineralization porphyry) had higher oxygen fugacity conditions than those of the pre-mineralization and post-mineralization rocks. The Chalukou Mo deposit formed in relation to the southward subduction of the Mongol-Okhotsk Ocean. Our study suggests that the subduction-related setting, crust-mantle interaction, and the large-scale magmatic intrusion were favorable factors to generate the super-large Mo deposits in this area.

Ore-forming fluid characteristics and ore-forming materials source of the Tudimiaogou – Yindongshan lead-zinc polymetallic orefield, west Henan

1 Introduction The Tudimiaogou-Yindongshan lead-zinc polymetallic orefield is located in the Tudimiaogou-Weimoshi lead and zinc silver polymetallic metallogenic belt.The belt is an important part of southwestern Henan lead and zinc

Characteristics of the ore-forming fluid in the Huayuan Pb-Zn ore filed, Northwest of Hunan Province, China

1 Geological Setting The Huayuan Pb-Zn ore field in Xiangxi is located in the southeastern margin of the Yangtze block and the mid-segment of the West Hunan-West Hubei metallogenic belt.The exposed stratum are the lower

Geological characteristics and the origin of ore-forming materials of(Laozhaiwan gold deposit, Yunnan Province

"Golden triangle"area bordered on Yunnan-Guizhou-Guangxi was one of the most important Carlin-type gold deposits concentration areas.Deep understanding of Carlin-type gold deposits in Guizhou and Guangxi Province had reached through several decades studies,but geological environment was very complex in the southeastern Yunnan,and Carlin-type gold deposits produced in the southeastern Yunnan were different from that of America,few studies were taken there.Based on a large number of field work,studies on the geological characteristics combining with geochemistry characteristics were taken,and analysis the genesis of Laozhaiwan gold deposit.The types of alteration in Laozhaiwan gold deposit were mainly silicification and pyritization,and Gold grade was high when silicification and pyritization were both occurred.It could be caculated that fluid density(g/cm3)varied from 0.7 to 4.9,salinity varied from 0.76%to 0.95%and ore-forming pressure(Pa)varied from 1.81×105 to 49.96×105 according to fluid inclusion test results,showed that Laozhaiwan gold deposit was hypabyssal hydrothermal deposit in low temperature and low salinity.According to composition of fluid inclusion analysis,combining with H-O isotope,made theδD-δ18O figure,showed that the fluid of the deposit rooted in formation water and mixed with meteoric waters later.

Mineral Geochemical Characteristics and Indication Significance of Biotite-Rutile in the Gabbro Intrusions in the Yinmin Iron-Copper District, Yunnan

1 Introduction After the Dongchuan Orogenic movement(Hudsonian Orogeny,ca.1800 Ma±),the tectonic basement layer of the continental crust on the Yangtze massif could have been formed.And then tectonic-magmatic emplacement

Ore-forming fluid characteristics and genesis of vein-type lead-zinc mineralization of Xiaohongshilazi deposit,Jilin Province, China

The Xiaohongshilazi mineral deposit in Jilin Province,China,is located in the accretion zone in the northern margin of the North China Block. The deposit contains two types of ore bodies: layered Pb-Zn ore bodies in volcanic rock and vein-hosted Pb-Zn ore bodies controlled by fractures. The vein Pb-Zn ore bodies are strictly controlled by tectonic fracture zones trending in S-N direction,which comprise sulfide veins or sulfidebearing quartz veins distributed along faults or structural fissures. The ores mainly appear mesh-vein and vein structures,and also show solid-solution separation and metasomatic textures. The metal minerals are mainly sphalerite,galena,and pyrite,etc. Wall-rock alteration includes mainly sericitization,chloritization,silicification and carbonatization,etc. Microscope observations and Raman spectroscopy analyses indicate that the oreforming fluid of the vein Pb-Zn ore bodies was mainly magmatic water with low temperature,low salinity,and a shallow depth of metallogenesis( ~ 1.5 km). Sulfur and lead isotope analyses indicate that the sulfide source is mainly formation sulfur or biogenic sulfur,which is similar to the sulfur source of hydrothermal deposit( negative( δ^(34) S values),while the main Pb source was the upper crust with some mantle input. This article argues that the vein Pb-Zn ore body of the Xiaohongshilazi deposit is a low-to medium-temperature hydrothermal vein type related to the formation of a shallow magma chamber.

Prediction of loess soil-water characteristic curve by mercury intrusion porosimetry

Mercury intrusion porosimetry(MIP)is a simple and fast way to obtain the pore distribution of soil and can be used to estimate the soil-water characteristic curve(SWCC).In previous studies,soil was assumed to be a perfect wettability material,and the contact angle(CA)of the soil-water interface was taken as zero in the SWCC prediction method.However,the CA has proved to be much greater than zero even for hydrophilic soils according to some soil wettability experiments,and it has a significant effect on predicting the SWCC.In this research,a method for predicting the SWCC by MIP,which takes the CA as a fitting coefficient,is proposed.The pore size distribution curves are measured by MIP,and the SWCCs of two loess soils are measured by pressure plate and filter paper tests.When the CA is taken as70°and 50°for the wetting and drying process,respectively,the SWCCs predicted by the pore size distribution curves agree well with the measured SWCCs.The predicted suction range of the proposed method is 0-105 k Pa.The consistency of the results suggests that utilizing the MIP test to predict the SWCC with a proper CA is effective for loess.

Ground water hydrochemical characteristics: seawater intruded area in eastern and southern coast of Laizhou Bay

Eastern and southern coastal zones of Laizhou Bay are the most representative seawater intruded areas in the world, with two intrusion sources of contemporary seawater and paleobrine. In order to reveal the complicated hydrochemical changing process and the mechanism of fresh groundwater being polluted by saltwater, we conducted long-term observation and hydrochemical analysis at four observing sections of typical salt-fresh water transitional zone. The study indicates that seawater and brine intrusion processes have different hydrochemical features, and that ion exchange and adsorption actions between water and aquifer produce great influence on the intrusion.

Research and Application of High-Density Resistivity Method in Seawater Intrusion Investigation in Laizhou Bay

The disaster of seawater intrusion seriously affects people's lives and restricts economic development,so the detection and treatment of seawater intrusion is a long-term task.On the basis of field investigation and water quality analysis,according to the change characteristics of apparent resistivity of groundwater after Cl-reaches 250 mg/L,the theoretical basis for the application of high-density resistivity method was determined,and the characteristic values of apparent resistivity for seawater intrusion interfaces in different geological characteristic regions in Laizhou Bay area were determined by typical profile tests.Combined with water quality investigation and other means,profiles for the high-density resistivity method were arranged,and the interfaces between saline and fresh water were accurately divided.

Igneous intrusion contact metamorphic system and its reservoir characteristics:A case study of Paleogene Shahejie Formation in Nanpu sag of Bohai Bay Basin,China

Taking the Paleogene Shahejie Formation in Nanpu sag of Bohai Bay Basin as an example,this study comprehensively utilizes seismic,mud logging,well logging,physical property analysis and core thin section data to investigate the metamorphic reservoir formed by contact metamorphism after igneous rock intrusion.(1)A geological model of the igneous intrusion contact met amorphic system is proposed,which can be divided into five structural layers vertically:the intrusion,upper metamorphic aureole,lower metamorphic aureole,normal sedimentary layers on the roof and floor.(2)The intrusion is characterized by xenoliths indicating intrusive facies at the top,regular changes in rock texture and mineral crystallization from the center to the edge on a microscopic scale,and low-angle oblique penetrations of the intrusion through sedimentary strata on a macroscopic scale.The metamorphic aureole has characteristics such as sedimentary rocks as the host rock,typical palimpsest textures developed,various low-temperature thermal metamorphic minerals developed,and medium-low grade thermal metamorphic rocks as the lithology.(3)The reservoir in contact metamorphic aureole has two types of reservoir spaces:matrix pores and fractures.The matrix pores are secondary"intergranular pores"distributed around metamorphic minerals after thermal metamorphic transformation in metasandstones.The fractures are mainly structural fractures and intrusive compressive fractures in metamudstones.The reservoirs generally have three spatial distribution characteristics:layered,porphyritic and hydrocarbon impregnation along fracture.(4)The distribution of reservoirs in the metamorphic aureole is mainly controlled by the intensity of thermal baking.Furthermore,the distribution of favorable reservoirs is controlled by the coupling of favorable lithofacies and thermal contact metamorphism,intrusive compression and hydrothermal dissolution.The proposal and application of the geological model of the intrusion contact metamorphic system are expected to promote the discovery of exploration targets of contact metamorphic rock in Nanpu sag,and provide a reference for the study and exploration of deep contact metamorphic rock reservoirs in the Bohai Bay Basin.

渤海湾盆地火成岩侵入接触变质系统及其储层特征--以南堡凹陷古近系沙河街组为例

以渤海湾盆地南堡凹陷古近系沙河街组为例,综合利用地震、录井、测井、物性分析和岩心薄片等资料,开展火成岩侵入接触变质岩储层研究。①提出火成岩侵入接触变质系统地质模式,该系统纵向上可划分为侵入体、上变质带、下变质带、顶板和底板正常沉积层5层结构;②侵入体特征主要表现为:顶部发育有指相意义的捕虏体,微观上岩石结构与矿物结晶由中心向边缘有规律变化,宏观上侵入体多以低角度斜穿沉积地层等;变质带特征主要为:原岩为沉积岩,发育典型的变余结构,出现多种中低温热变质矿物及岩性为中低级热变质岩等;③接触变质带储层发育基质孔隙和裂缝两种储集空间类型,基质孔隙为变质砂岩烘烤变质改造后围绕变质矿物分布的次生“粒间孔隙”,裂缝主要为变质泥岩中的构造缝和侵入挤压缝,具有层状、斑状和沿裂缝浸染状3种分布方式;④变质带储层分布主要受热烘烤强度的控制,优质储层分布是有利岩相与热接触变质、侵入挤压和热液溶蚀等作用互相耦合共同控制的结果。侵入接触变质系统地质模式的提出和应用,有望推动南堡凹陷接触变质岩勘探目标的发现,为渤海湾盆地深层接触变质岩储层研究和勘探提供参考依据。

深层砂岩储层孔隙结构特征及影响因素——以银额盆地拐子湖凹陷为例

以银额盆地拐子湖凹陷巴音戈壁组深层砂岩为研究对象,在探究储层基本特征的基础上,采用恒速压汞法区分孔隙与喉道,定量地表征孔喉特征参数;通过扫描电子显微镜和铸体薄片,定性地表征孔喉形态特征,分析微观孔隙的结构差异;结合孔喉分形维数划分孔隙类型,探讨影响储层孔隙发育的主要因素。研究结果表明,该区储层岩石类型以长石岩屑砂岩为主,成分成熟度较低,平均孔隙度为10.8%,平均渗透率为1.17 mD,属于低孔低渗型储层。储集空间类型主要为原生粒间孔、溶蚀孔和微裂缝,孔隙半径平均值为195μm,喉道半径平均值为3.5μm,储层的孔隙结构类型分为微孔小喉型、小孔小喉型和大孔粗喉型。研究区储层孔喉比总体上较大,良好的孔喉配置关系是影响储层物性的重要因素,影响孔隙发育的主控因素则是早期成岩作用、有机酸溶蚀和烃类充注的综合作用。经过相对较弱的压实作用和胶结作用改造后,原始碎屑为后期溶蚀提供了物质和空间基础,储层顶部和底部巨厚的富有机质泥岩提供了有机酸溶蚀和烃类充注的物源。

路侧侵扰影响下的机动车速度特性分析及预测

低等级道路路侧侵扰现象频繁,冲突严重,紊乱无序。准确预测其复杂交通行为特性,可揭示路侧侵扰影响下的交通事故发生机制。为此采集低等级公路和城市道路5类常见的路侧侵扰源视频,提取高分辨率车辆微观轨迹,获取行经侵扰区的车辆速度,划分侵扰区特征断面,分析车速时空特性演变规律,采用线性、对数以及三次回归建立车速预测模型。三次回归模型在侵扰区复杂场景下表现出更好的车速预测性能。结果表明:低等级城市道路侵扰区的车速降幅普遍高于公路,驾驶人在侵扰源及附近减速效应显著,当驾驶人与侵扰主体的意图协调后,驾驶人会加速通过前方侵扰区,但当侵扰主体的行为意图难以预测时,车速会出现一定波动。

基于煤层挥发分的狐偃山岩体隐伏形态特征研究

为了寻找狐偃山岩体隐伏形态特征,基于侵入岩体侧畔煤层挥发分的空间变化特征,刻画侵入岩体在煤系地层中的隐伏形态特征机理;依据西山煤田狐偃山岩体附近469组煤层挥发分数据及前人研究结果,通过制作研究区内02^(#)、2^(#)、6^(#)、8^(#)、9^(#)煤层挥发分等值线图、垂直挥发分变化方向剖面图,研究了煤层挥发分与侵入岩体距离关系。结果表明:狐偃山侵入岩体侧畔依次出现接触变质带、恒温变质带、耗散变质带及正常煤带,岩体影响带宽度在7 km左右,其中接触变质带的宽度在1 km以内,恒温变质带宽度在4~5 km范围内,耗散变质带宽度在2~4 km范围内;狐偃山侵入体在煤系中的隐伏形态为一大型岩体,其中9^(#)煤层下伏有多个小型岩株,煤层自上而下遭受岩体烘烤影响的程度逐渐增大。

单、双孔隙结构非饱和黏土孔隙分布变化规律试验研究

由于孔隙分布曲线的复杂性,在非饱和过程中黏土的孔隙结构变化规律尚不明晰,这导致基于孔隙分布模型计算土-水特征曲线存在较大的误差。针对这一问题,基于干缩试验与压汞试验,对单孔与双孔结构重塑黏土在脱湿过程中孔隙分布曲线的变化规律进行了定量分析。研究表明:在脱湿过程中孔隙分布曲线存在平移、缩放等变换。构建了t分布和双t分布函数,提取了孔隙分布曲线的自由度、峰值、峰值对应的孔隙直径作为特征参数来表征孔隙分布变化规律,发现了特征参数和土样孔隙比之间存在较好的线性关系。基于试验结果,建立了含水率-孔隙比-孔隙分布曲线关系,提出了一个考虑孔隙结构变化的重塑黏土土-水特征曲线计算框架。最后,与试验测得的土-水特征曲线进行比较,验证了所提出的计算方法的准确性。

复合调理对淤泥机械压滤脱水特性的影响机理分析

机械压滤脱水是广泛应用的河湖淤泥脱水工艺,淤泥调理方式是影响机械压滤脱水效率的关键因素之一,采用聚丙烯酰胺(PAM)为代表的絮凝剂调理以及絮凝剂与无机调理剂联用的复合调理是2种典型的淤泥调理措施。复合调理近年来发展迅速,研究絮凝剂单一调理与复合调理对机械脱水效率的影响、探索作用机理,对淤泥机械压滤脱水的工艺优化具有重要意义。以官田湖底泥为试验对象,对比PAM、新型低碱性淤泥改性剂(LAC)的淤泥调理、脱水效果,分析PAM及PAM+LAC复合调理淤泥脱水工艺参数,利用压汞试验与扫描电镜(SEM)揭示复合调理对脱水泥饼结构影响。结果表明,调理药剂的促进作用主要在过滤脱水阶段最显著;LAC具有替代和强化PAM调理效果的作用,改善了泥饼卸料性能;加入LAC有助于维持泥饼骨架结构和增大泥饼孔隙,增加的孔隙以开口孔隙为主。

潍北平原卤水入侵层位识别及垂向分布时空特征

通过在年内枯、丰水期对咸水入侵锋线处的地下水进行分层监测和取样,利用水化学和稳定同位素测试结果,分析惰性示踪剂和反应示踪剂的空间和时间变化特征。结果表明:从卤水入侵的空间分布特征上,浅表层地下水与卤水入侵的相关性较差,卤水入侵主要发生在浅层和中层地下水含水层中、深层地下水入侵程度相对较弱;不同地区入侵层位存在差异,弥河冲洪积扇入侵层位为浅表层及浅层,白浪河冲洪积扇入侵不明显,潍河冲洪积扇入侵层位为中深层。在平面上呈现南部偏淡、中部为卤水分布区、北部为海水的分布形态。淡水样品呈现中深层咸水入侵为主导的现象。咸水入侵呈现顺层楔形入侵,局部发生一定程度的越流入侵,即下部地下咸水入侵上部地下淡水。从卤水入侵的时间分布特征上,枯水期时咸水入侵在垂向上呈现楔形态势,丰水期时20~50 m的主要入侵层位的淡水向滨海推进,浅部和深部的入侵仍然在持续进行,深层水咸水入侵程度更高。本研究加深了对潍北平原咸水入侵的认识。为了进一步探明咸水入侵的周期性规律,进行水文地球化学长期分层监测十分具有必要性。

大红山矿区二道河铁矿床地质特征及成因分析

在二道河铁矿矿权内实施了钻探、坑探、取样、水工环地质调查等地质工作,对矿床进行了系统的揭露和控制。通过对各项勘察结果的综合分析,认为二道河铁矿床含矿地层为大红山群红山组地层,含矿围岩为变钠质熔岩,矿体产状和地层产状具有明显的相似性。矿体呈现上缓下陡的特征,厚度变化属复杂型,矿体内部结构复杂程度属中等型。该矿床属海底火山沉积-变质改造型矿床,即由海底火山喷流作用形成,且受后期变质改造富集作用而形成矿床。认为辉绿岩侵入体对二道河铁矿成矿的贡献是双向的,既对成矿有利,又对形成的铁矿床有一定的破矿作用,但成矿效应大于破矿效应。

Prediction of salinity intrusion in the sheltered estuary of Terengganu River in Malaysia using 1-D empirical intrusion model

Generally one dimensional （l-D） empirical salinity intrusion model is limited to natural alluvial estuary. However, this study attempts to investigate its ability to model a sheltered alluvial estuary of the Terengganu River in Malaysia. The constructed breakwater at the mouth of the river shelters the estuary from direct influence of the open sea. The salinity density along the estuary was collected during the wet and dry seasons for scenarios before and after the constructed breakwater. Moreover, the freshwater discharges, tidal elevations and bathymetry data were also measured as model inputs. A good fit was demonstrated between simulated and observed variables, namely salinity distribution and intrusion length for both scenarios. Thus, the results show that 1-D empirical salinity model can be utilized for sheltered estuarine condition at the Terengganu Estuary, but with an appropriate determination of an initial point. Furthermore, it was observed that the salinity intrusion in the study area is largely dependent on the freshwater discharge rather than tidal elevation fluctuations. The scale of the salinity intrusion length in the study area is proportional to the river discharge of the -1/2 power. It was appeared that the two lines of the 1-D empirical salinity model and discharge power based equation fitted well to each other, with the average predicted minimum freshwater discharge of 150 m^3/s is going to be required to maintain acceptable salinity levels during high water slack （HWS） near the water intake station, which is located at 10.63 km from river mouth.