新疆磁海铁矿区镁铁质岩及正长岩锆石U-Pb年代学、岩石地球化学特征:对成岩、成矿作用的制约

对新疆磁海铁矿区镁铁-超镁铁质岩与铁成矿关系、正长岩与镁铁质岩关系的解剖,是认识磁海矿区成岩、成矿过程及构造背景的关键。本文利用SIMS锆石U-Pb测年法,获得磁海辉绿岩、辉长辉绿岩、磁南辉长岩、磁海北角闪石英正长岩的206Pb/238U-207Pb/235U谐和年龄分别为275.1±2.2Ma、281.9±3.2Ma、273.0±1.9Ma和273.0±1.8Ma,这与北山乃至北疆地区主要含铜镍-钒钛磁铁矿的镁铁-超镁铁质岩年龄一致。岩石地球化学特征研究显示,从辉石岩到辉长岩,再到辉绿岩,经历了Ti逐渐富集、Mg#和m/f值先增加后降低的过程,角闪石英正长岩具有A型花岗岩特征,与辉长岩、辉绿岩在成因上存在互补关系。综合年代学和地球化学特征,磁南辉石岩、辉长岩、磁海辉绿岩、辉长辉绿岩以及磁海北边的角闪石英正长岩为同源岩浆演化的产物,岩浆演化过程中受地壳混染作用微弱,在岩浆演化的早期,磁铁矿的结晶分离主导着岩浆成分的改变,当岩浆演化到辉长岩阶段,岩浆开始以结晶分异作用为主;磁铁矿的分离结晶时间早于钛铁矿,岩浆型的金属硫化物为磁铁矿和钛铁矿结晶过渡阶段的产物。磁海镁铁-超镁铁质岩石在成岩及成矿作用上可能与在时间和空间上相邻近的塔里木早二叠世大火成岩省有密切关系。     

新疆某铁矿高精度磁法勘探的应用

地面高精度磁测作为重要的物探方法之一,在开展战略性矿产远景调查项目及地质填图中得到广泛应用。利用地面高精度磁法在沉积变质型磁铁矿地区的应用效果,在新疆某铁矿勘探中,依据该区域磁异常成果并结合该区域地质特征,通过磁法工作确定该铁矿大致分布形态,获得较好的地质效果,阐述了地面高精度磁测工作在地质找矿中的意义。     

陕西省紫阳县朱溪河钛磁铁矿地质特征

紫阳县朱溪河钛磁铁矿区分布着北西向碱基性岩脉群,钛磁铁矿体多产于规模大、分异好的辉绿岩体中部暗色相带内,与围岩呈渐变过渡关系,产状与含矿岩体产状基本一致。矿石自然类型为浸染状钛磁铁矿,矿石工业类型为需选弱磁钛磁铁矿石,矿床成因类型为岩浆晚期分异型。大比例尺磁法测量磁异常能较好的反映成矿信息。     

重磁综合物探方法在大勐龙地区铁矿勘查中的应用

重力、磁法是寻找和圈定磁铁矿床经济有效的地球物理手段,通过大勐龙地区大中比例尺重、磁物理场测量和异常分析,结合火山喷溢沉积—气液变质改造型磁铁矿床的基本特征,建立了研究区的地质-地球物理磁铁矿找矿模型.并以此模型对区内圈定的重、磁物探异常进行对比、分析,不仅扩大了已知矿床的规模,而且发现了隐伏磁铁矿体.     

柬埔寨王国贡布省速富县本库比磁铁矿床地质地球物理特征及找矿标志

柬埔寨王国贡布省速富县拉巴乡本库比磁铁矿床是产于大面积第四系覆盖区下由磁铁角闪辉石岩、辉绿岩、斜长岩、斜长花岗岩组成的杂岩体内的矿床,本文通过对矿床地质地球物理特征的论述,揭示矿体产出的地质特征及赋存规律,总结提出了区域上的找矿标志：（1）地势较高地段分布的崩塌积成因的褐铁矿碎块是直接的找矿标志;（2）磁法勘探所圈定的磁异常是重要的找矿标志.（3）与矿区同期次出露的磁铁角闪辉石岩、斜长岩、辉绿岩体及斜长花岗岩组成的杂岩体或单独某一岩类是重要的找矿标志.     

高精度磁测在新疆西昆仑某隐伏磁铁矿勘探中的应用

在偏远、高寒地区开展地质勘查工作难度非常大,本次工作采用高精度磁法对新疆西昆仑某隐伏磁铁矿进行勘探。通过对磁法勘探数据进行处理,圈定了磁异常,通过对磁异常的分析,了解了隐伏矿体的展布形态,同时通过对磁测数据的反演,获得了矿体深部的空间特征,为矿山勘探节省了大量的时间和资金。     

综合物探法在东昆仑依阡巴达铁矿勘查中应用

在东昆仑祁漫塔格依阡巴达地区运用综合物探法发现多条磁铁矿体,增加了铁矿资源量,取得较好地质找矿成果。通过对M-1-1磁异常开展工作,查明高重力、高磁异常组合特征,经钻探工程验证为隐伏磁铁矿体引起。据此提出寻找矽卡岩型磁铁矿床采用以磁法为主、重力及电测深综合物探方法为辅的技术组合。     

安徽庐江泥河铁矿的发现及意义

泥河铁矿是在玢岩铁矿模式、大型矿集区成矿理论的指导下,通过系统分析和研究庐枞地区成矿地质条性和成矿规律,选择1:5万航磁异常与重力异常套合地区,在1:1万地磁测量基础上,利用钻探对磁异常进行验证而发现的,这一发现是长汀中下游地区近20年来找矿的重大突破之一.勘探成果表明,泥河铁矿是一个由大型磁铁矿、大型硫铁矿、中型硬石...     

纳米比亚奥姆博姆博航磁异常特征及找矿意义

纳米比亚奥姆博姆博地区ΔT航磁化极异常以正异常为主,反映了朝斯组的分布范围。磁铁矿露头是找矿直接标志,一般分布在磁异常梯度带上。朝斯组高磁异常带是寻找磁铁矿床的优选目标靶区。通过野外地质调查及钻井揭露,在高磁异常带上发现了较好的磁铁矿体,预测该地区具有较大磁铁矿勘探潜力。     

地面磁法测量在白山市五道羊岔铁矿勘查中的应用

以1:5 000比例尺进行地面磁法测量,采用廊坊物探大队研究所生产的电子垂直磁力仪,读取垂直磁场ΔZ。在此基础上,根据磁铁矿赋存于斑杂状斜长角闪岩中,二者都具有磁性的特点,进行间接找矿。同时,对比分析已知铁矿体磁场特征,建立磁铁矿地质-地球物理找矿模型,进行找矿预测。进而在重点区段实施初步工程验证,见矿率高,从而说明了地面磁法测量找寻磁铁矿的可行性和有效性。     

赣南新林屋—均村地区低磁性隐伏岩体的识别:来自重磁场的证据

通过在赣南新林屋—均村地区开展1∶5万高精度磁法测量工作,结合1∶20万重力测量数据,以岩石物性为基础,分析该区重磁异常并圈定隐伏花岗岩体。新林屋—均村地区低磁性、低密度的花岗岩侵入至具有磁性的前寒武纪变质岩中,形成磁低重低的异常特征;推断新林屋—均村地区存在1个呈NW向展布的隐伏花岗岩体,该隐伏花岗岩体浅部受SN—NE向弧状断裂控制,深部受NW向断裂控制,浅部分布范围较深部更广。这些信息为该区进一步找矿提供了基础地球物理资料,也为同类地区寻找隐伏花岗岩体提供参考。     

用高精度磁测识别动漫设备Xsens系统干扰源

为了查明苏州某数字公司新规划区内是否存在影响Xsens惯性动作捕捉系统摄影质量的磁性干扰源,首先在已有影棚内灵活运用不同探头高度的磁场测量结果,准确判断出了2号工作间存在影响Xsens系统摄影质量的磁性干扰源。依此方法,实测了新规划区域的磁场,并推断规划区内的磁场强度不足以对Xsens系统造成干扰,且已得到了证实。     

Surveying the anthropogenic impact of the Moldau river sediments and nearby soils using magnetic susceptibility

Measuring magnetic susceptibility is a method which is used to estimate the amount of magnetic particles in soils, sediments or dusts. Changes in magnetic susceptibility can be due to various reasons: input from different sources of sediments, e.g. from different soils or rocks, atmospheric fallout of anthropogenic dusts containing magnetic particles produced by fossil fuel combustion, steel production or road traffic. In the case of river sediments, input from the catchment is of primary significance. The main aim of this investigation was to test the potential of magnetic susceptibility screening in identifying the effect and significance of anthropogenic activities in an area with complex geological conditions. We investigated the magnetic susceptibility of riverbed sediments of the largest river of the Czech Republic, the Moldau river. Besides that, the magnetic signal of nearby topsoils as well as of outcropping bedrocks in the vicinity of the river was examined. In the upper 300 km of the river, the magnetic enhancement of the river sediments can be linked to anthropogenic activities. Positive correlations were found in the river sediments between the contents of Cu and Zn and magnetic susceptibility, while Fe, Mn and Ni did not show a correlation with magnetic susceptibility. However, the major geogenic magnetic anomaly in the area around the Slapy dam has made it impossible to unambiguously interpret the magnetic signal in terms of anthropogenic impact in the last 80 km downstream.     

东海陆架平北地区残留沉积磁性特征及其油气指示意义

本文利用1994－1995年在东海陆架平北地区获取的370个柱状样,对该区残留沉积物作磁性测试和磁性矿物鉴定,以进行陆架残留沉积物磁性特征与深部油气渗漏关系的研究。磁性测试显示本区存在磁化率异常和饱和等温剩磁异常两种磁性异常现象。根据磁性参数特征和多种矿物物理学鉴定结果,确定导致本区磁化率异常的矿物为陆源碎屑磁铁矿,导致剩磁异常的矿物为自生或次生铁硫化物胶黄铁矿和磁黄铁矿。证据显示本区剩磁异常是油气渗漏的产物;而磁化率异常则主要指示古滨海砂的分布。作者提出在本区的油气化探中,剩磁参数是有效的化探磁性指标。     

综合物探方法在甘肃梧桐井铁铜多金属矿勘查中的应用

甘肃梧桐井铁铜多金属矿区已发现的铁铜矿体主要产于大理岩和斜长花岗岩接触带上,严格受北东向断裂控制。在该矿区实施了1∶10000地面高精度磁测和1∶10000激电中梯测量工作。综合研究物探异常发现,不论磁异常还是激电异常,其展布方向均与矿区地层、构造走向基本一致,与地质构造关系密切,具有重要的找矿意义。圈定的磁异常和激电异常都是该区勘查铁、铜矿的直接找矿标志。激电异常和磁异常同时出现,特别是当激电异常处于磁异常强梯度带上时应高度重视。本次研究利用综合物探方法,结合矿区地质特征,进行了成矿预测,有效地指导了地质找矿工作,取得了较好的勘查效果。     

谢通门色药异常区铜找矿前景浅析

本文在区域地质、水系沉积物测量、土壤测量和高精度磁测等方面对色药异常区的铜找矿前景进行初步分析。利用1∶5万水系沉积物测量编制异常图,发现区内Mo、Cu、Bi、Pb、Zn、Sb、Sn、W、Ag、Hg等元素均有不同规模的异常,且Mo、Cu异常规模较大。通过高精度磁测结果显示区内有3个磁异常,已知铜矿化点均位于磁异常附近。通过土壤测量数据研究元素间的组合关系,推断区内可能的矿床类型与酸性侵入岩有关的斑岩型铜多金属矿。并对区内已发现的1号铜矿化点进行重点研究,表明区内寻找与中酸性侵入岩有关的铜多金属矿具有良好的找矿前景。     

黄河源地区磁组构特征及其地质意义

黄河源区位于青藏高原东北部,区内主要为三叠系沉积地层,发育一系列由北向南的推覆构造带,间有早期近直立的韧性剪切带。笔者对黄河源地区巴颜喀拉山群沉积岩进行了磁组构分析,结果显示岩石磁化率各向异性度P值和磁化率百分率各向异性度H值均不大,反映该地区总体韧性变形较弱,较强韧性变形仅发育于局部地段;岩石磁组构具有磁面理发育、磁线理不发育、磁化率椭球呈压扁形椭球体的特点,反映在挤压应力作用下,岩石发生了压扁变形,主应力方位主要为NNE-SSW(近SN)向,其次为NE-SW向。根据岩石磁组构分析认为黄河源地区存在两条韧性剪切带,韧性剪切带与现今湖泊水体的展布有一定的耦合关系;北部韧性剪切带沿现今黄河河谷分布,控制着扎陵湖、鄂陵湖和玛多"四姐妹湖"的展布;南部韧性剪切带沿岗纳格玛错—野牛沟一线展布,控制着岗纳格玛错和尕拉拉错等残余湖泊的分布。     

藏东昌都地区侏罗纪岩石磁组构研究及其构造意义

本文对藏东昌都地区侏罗纪汪布组、东大桥组和小索卡组红层共71个采点开展了磁组构(AMS)研究。磁组构测试结果表明,早侏罗世汪布组岩石磁线理较磁面理发育,磁化率各向异性度较高,磁化率椭球最小轴K3散布于层面缩短方向,代表了与构造成因相关的磁组构;中侏罗世东大桥组和晚侏罗世小索卡组岩石则磁面理较磁线理发育,磁化率各向异性度较低,磁化率椭球最小轴K3与层面近垂直,指示了原生沉积磁组构。早侏罗世汪布组地层的磁组构揭示了其构造应力场方向为NE-SW向。中侏罗世东大桥组的磁组构指示了其沉积时的古水流方向为SE向(138.3°),而晚侏罗世小索卡组磁组构指示了其沉积时的古水流方向为NNW向(328.3°)。古水流方向的明显变化揭示了昌都地区从中侏罗世到晚侏罗世沉积物物源发生了相应的转变,表明昌都地区南早北晚的隆升过程。     

3-D magnetic inversion and satellite imagery for the Um Salatit gold occurrence,Central Eastern Desert,Egypt

The Um Salatit is a gold occurrence situated in the Central Eastern Desert of Egypt. The studied area is characterized by an intensive imbrication zone of serpentinites and metavolcanic rocks. The integrated use of aeromagnetic and spectral reflectance remote sensing data has proved effective for mapping geology related to ore deposits. Spectral reflectance maps have been produced to discriminate various rocks, such as serpentinites, gabbros, and metavolcanic rocks. 3-D inversion of aeromagnetic data acquired over the Um Salatit study area produced a 3-D magnetic susceptibility model showing magnetic bodies surrounded by less magnetic host rock. The magnetic features are elongated ENE-WSW parallel to the major thrust fault and mapped the Um Salatit serpentinized rocks. Remote sensing data allow investigating surficial geological features and mapping the mineralized areas. Remote results, in conjunction with 3-D inversion of aeromagnetic data, demonstrate that gold occurrence in the study area was effectively restricted to the highly magnetic zone interpreted as host rocks.     

Deformation history inferred from magnetic fabric in the southwestern Okcheon metamorphic belt, Korea

Magnetic fabric and rock-magnetic studies have been carried out for the non-fossiliferous, low- to medium-grade metasedimentary rocks in the southwestern part of the Okcheon metamorphic belt (OMB). Two major metamorphic events in the study area were previously recognized: regional metamorphism (M₁) in the late Carboniferous to early Permian and contact metamorphism (M₂) due to the intrusion of granite in the middle Jurassic. The metamorphic grade of the study area increases from the biotite zone in southeast through the garnet zone to the staurolite zone towards the northwest. Magnetic fabrics of the study area are generally well defined and can be characterized according to the metamorphic zones. Magnetic foliation is the dominant magnetic fabric in the biotite zone, while magnetic lineation prevails in both garnet and staurolite zones. We interpret the metamorphism-related deformation history of the study area based on magnetic fabrics, magnetic mineralogy and previously reported metamorphic evolution as follows. Penetrative NW-dipping cleavage, represented by magnetic foliation, was formed in the study area by prevailing NW–SE shortening event during the M₁ regional metamorphism in the late Carboniferous–early Permian. This shortening event is interpreted to be associated with the collisional event between the North and South China blocks. Cleavages dipping steeply to the southeast in the staurolite zone are attributed to the pressure exerted from the intrusion of Jurassic granite in the northwestern area.