卧龙湖煤矿岩浆侵入特征及控制因素分析

岩浆侵入对煤矿生产影响极大,淮北煤田卧龙湖煤矿是受岩浆侵入较严重的矿井之一,其地质构造是控制岩浆侵入和岩浆岩展布的重要因素。卧龙湖煤矿自侏罗纪以来岩浆活动剧烈,发生了中性岩浆的侵入,多以岩床形式顺层侵入煤层顶底板及煤层中间。本文基于矿区钻孔数据揭露的岩浆岩分布情况,分析了结果表明卧龙湖矿区岩浆侵入规律,受煤层的形态、结构、理化性质以及产状的控制。     

一种改进的点与多边形关系的叉乘判别法

本文针对叉乘判别法只适用于凸多边形的缺陷提出了改进,将其推广至凹多边形和自相交多边形,改进方法利用叉乘值的正负变化,选择对点的积分路径,从而判断是否有闭合的路径包围被测点。并通过检测多边形是否环绕被测点,判断点与多边形的关系,属于非零环绕数法。经过实验,改进方法被证明有较快的速度和较强的适应性。     

一种提高大比例尺航测精度的方法试验研究

针对现有规范关于1∶500与1∶1000平坦地形测图必须采用全野外高程控制测量的规定,本文的试验采用装载组合宽角相机的无人飞艇低空航测系统,通过空中三角测量内业方法,突破了此技术限制。文中详述了三个试验测区的地理状况,以及采用的控制网布设方法,尤其是新设计的标志点之优点。成果表明,用航测内业加密方法所成图的高程和平面精度均超过现有规范标准。说明利用无人飞艇低空航测系统可以实现1∶500和1∶1000测图的全部航测任务,符合"允许采用新技术以更高质量的成果突破现有规范限制"的规定。     

气象业务系统融入“天擎”“天镜”的技术要点分析

随着气象业务系统的集约化程度越来越高,“云”+“端”的业务构建模式将成为主流,省级气象部门新的业务系统构建直接基于“天擎”作为数据和算力支撑,“天镜”提供统一实时业务监控的模式开展。而原来研发的气象业务系统则要通过“云化”改造融入“天擎”“天镜”。本文通过分析融入“天擎”“天镜”技术要点,总结贵州前期系统融入过程中的经验,为今后各单位业务系统顺利融入提供借鉴和指导。     

滇西大理至瑞丽铁路沿线地温场特征及其工程地质意义

在整理、分析云南大理至瑞丽拟建铁路沿线及其邻区现今地温场分布特征的基础上,进一步总结前人的资料,综合研究、探讨了该区地温场与岩浆活动、活动构造、地震活动、区域深部构造的关系。结果表明,该区中高温温泉（中高地温场）的空间分布与地表岩浆岩的出露、地表主要活动断裂带的分布都具有较好的对应关系。综合研究后认为,该区的中高温温泉可归结为岩浆热源型、断裂深循环型和岩浆热源叠加断裂深循环作用型3种基本成因类型。同时还发现,该区的温泉分布与区域地震活动空间上也存在密切的关系,并据此将区内划分为4个地震区带。研究结果表明,本区地表温泉分布所反映出的地温场特征对本区的工程稳定性评价具有重要的指示意义。     

评花岗岩的哈克图解

哈克图解是研究岩浆岩地球化学必用的图件,许多结论就是根据哈克图解做出的。哈克图解只是一个逻辑推理的工具,它所推出的结论是否正确,不是由图解本身决定的,而是由实践决定的。岩浆演化的理论是对的,岩浆演化的理论是从研究层状侵入体得来的,它仅适用于玄武质岩浆,而不适用于花岗质岩浆。实践是检验真理的唯一标准,由哈克图解得出的结论没有经过实践的检验是不能成为真理的,这是最基本、最简单的道理。     

西藏驱龙斑岩铜矿床岩浆演化过程中的Cu同位素分馏

随着同位素测试技术的发展,高温下重同位素分馏逐渐运用到地球化学领域.为了探索岩浆演化过程中是否会发生Cu同位素分馏,文章对西藏驱龙斑岩铜矿床同来源、不同演化阶段的两套岩浆岩(闪长岩包体和花岗闪长岩)进行了Cu同位素测试.测试结果显示,闪长岩包体的δ65Cu值集中在+0.08‰-+0.35‰之间,平均值为+0.25‰,花岗闪长岩的δ65Cu值为+0.42‰～+0.87‰,平均值为+0.60‰.△65Cu花岗闪长岩-闪长岩包体≈+0.4‰,并且δ65Cu值与样品w(SiO)变化存在一定的正相关性.结合地质学及同位素方面考虑,花岗闪长岩和闪长岩包体的Cu同位素组成差异可能是岩浆演化过程中发生了Cu同位素分馏所致.在驱龙矿区中新世岩浆演化过程中,随着岩浆去气作用,63Cu随HS-、Cl-等挥发分优先进入气相,导致残留岩浆熔体相对富集65Cu.此外,两者的Cu同位素组成差异也可能与岩浆演化过程中斜长石、角闪石、黑云母等矿物的不断结晶分离有关,矿物结晶分离时,基性矿物富集63Cu,而残余熔体则富集65Cu.     

玄武岩成分变异原因

笔者等研究发现山东栖霞和浙江西垄两地新生代玄武岩中分别产有奇特的富钾霞石质和富透长石质熔体玻璃地幔捕虏体,而且它们与寄主玄武岩之间有强烈的混染反应.表明玄武岩浆不是一元系岩浆,而是不同期多元系岩浆.多元系所占比例差别很大,决定了玄武岩浆成分的多样性.另外,此玄武岩成分也很特别:①不见斜长石,主要是铬透辉石(Mg质太多);②含有较多霞石;③全岩SiO2低,37％ ～39％.此玄武岩应称为透辉石岩.     

Miocene andesitic lavas of Sierra de Angangueo: a petrological,geochemical, and geochronological approach to arc magmatism in Central Mexico

ABSTRACT

The early and middle Miocene andesitic lavas of the Sierra de Angangueo (MALSA) represent one of the most prominent landforms of intermediate magmatism in Central Mexico. In this paper, we present new petrological, geochemical, thermobarometric, and geochronological data in order to discuss the conditions of MALSA’s emplacement in the lithosphere.

MALSA comprises a voluminous eroded early Miocene andesitic structure, emplaced on a Mesozoic basement. MALSA shows a wide variety of textures, from glassy and aphanitic to porphyritic, mainly composed of plagioclase (An_10-55), clinopyroxene (Wo_60-65; En_35-40), amphibole (Mg-hornblende/edenite), and rarely olivine (Fo_75–86) or orthopyroxene (En_72-80). Major and trace elements plots follow a typical calc-alkaline trend with relatively increasing fractionation.

The ⁸⁷Sr/⁸⁶Sr isotopic signatures range between 0.703343 and 0.704459 and εNd values from +1.37 to +4.84; apparently without a significant contribution of an old, thick, or highly radiogenic continental crust. Lead isotope values ²⁰⁶Pb/²⁰⁴Pb vary between 18.68 and 18.83, ²⁰⁷Pb/²⁰⁴Pb from 15.57 to 15.65, and ²⁰⁸Pb/²⁰⁴Pb from 38.39 to 38.67, suggesting contamination of magmas by juvenile crust. Thermodynamic calculations indicate equilibrium conditions at ≤900°C and ~2 kbar and an average log ?O₂ ≈ ?10.

Ar–Ar and K–Ar dating carried out on whole rock, matrix, amphibole, and plagioclase phenocrysts yielded ages between 13.0 ± 0.5 and 23.9 ± 0.3 Ma. These dates indicate a series of pulses with maximum magmatic activity between 24 and 18 Ma.

The geochemical and petrologic data suggest partial melting processes in the lower or middle crust associated with possible magma mixing during its ascent; such a mechanism could explain a hybrid mantle-lower crust origin of this large volume of andesites. The MALSA, as well as the early to middle Miocene magmatism from Western Mexico, could represent two coeval and independent magmatic arcs prior to the present Trans-Mexican Volcanic Belt (TMVB) in Central Mexico.     

Timing of granitic magma mixing in the southeastern Gyeongsang Basin,Korea: SHRIMP-RG zircon data

Late Cretaceous calc-alkaline granites in the Gyeongsang Basin evolved through the mixing of mafic and felsic magmas. The host granites contain numerous mafic magmatic/microgranular enclaves of various shapes and sizes. New SHRIMP-RG zircon U–Pb ages of both granite and mafic magmatic/microgranular enclaves are 75.0?±?0.5 Ma and 74.9?±?0.6 Ma, respectively, suggesting that they crystallized contemporaneously after magma mixing. The time of injection of mafic melt into the felsic magma chamber can be recognized as approximately 75 Ma by field relations, petrographic features, geochemical evolution, and SHRIMP-RG zircon dating. This Late Cretaceous magma mixing event in the Korean Peninsula was probably related to the onset of subduction of the Izanagi (Kula)–Pacific ridge.