The Catalão I niobium deposit, central Brazil: Resources, geology and pyrochlore chemistry

The Catalão I alkaline–carbonatite–phoscorite complex contains both fresh rock and residual (weathering-related) niobium mineralization. The fresh rock niobium deposit consists of two plug-shaped orebodies named Mine II and East Area, respectively emplaced in carbonatite and phlogopitite. Together, these orebodies contain 29 Mt at 1.22 wt.% Nb₂O₅ (measured and indicated). In closer detail, the orebodies consist of dike swarms of pyrochlore-bearing, olivine-free phoscorite-series rocks (nelsonite) that can be either apatite-rich (P2 unit) or magnetite-rich (P3 unit). Dolomite carbonatite (DC) is intimately related with nelsonite. Natropyrochlore and calciopyrochlore are the most abundant niobium phases in the fresh rock deposit. Pyrochlore supergroup chemistry shows a compositional trend from Ca–Na dominant pyrochlores toward Ba-enriched kenopyrochlore in fresh rock and the dominance of Ba-rich kenopyrochlore in the residual deposit. Carbonates associated with Ba-, Sr-enriched pyrochlore show higher δ¹⁸O_SMOW than expected for carbonates crystallizing from mantle-derived magmas. We interpret both the δ¹⁸O_SMOW and pyrochlore chemistry variations from the original composition as evidence of interaction with low-temperature fluids which, albeit not responsible for the mineralization, modified its magmatic isotopic features. The origin of the Catalão I niobium deposit is related to carbonatite magmatism but the process that generated such niobium-rich rocks is still undetermined and might be related to crystal accumulation and/or emplacement of a phosphate–iron-oxide magma.     

Book Reviews

Books reviewed:
M. Petrou and P. Bosdogianni, Image Processing, The Fundamentals
S. N. Lane, K. S. Richards and J. H. Chandler, Landform Monitoring, Modelling And Analysis
T. M. Lillesand and R. W. Kiefer, Remote Sensing And Image Interpretation
A. S. Câmara and J. Raper, Spatial Multimedia And Virtual Reality
M. N. Demers, Fundamentals Of Geographic Information Systems
J. L. Casanova, Remote Sensing In The 21st Century: Economic And Environmental Applications
G. McGrath and L. M. Sebert, Mapping A Northern Land: The Survey Of Canada
A. S. Milman, Mathematical Principles Of Remote Sensing: Making Inferences From Noisy Data
K. Kraus, Photogrammetrie Band 3: Topographische Informations-systeme
E. M. João, Causes And Consequences Of Map Generalisation
R. B. Parry and C. R. Perkins, World Mapping Today
P. M. Mather, Computer Processing Of Remotely Sensed Images: An Introduction
M. E. Schaepman, Calibration Of A Field Spectroradiometer
J. C. Iliffe, Datums And Map Projections For Remote Sensing, Gis And Surveying     

大别山地区三个花岗岩体的地球化学特征及其成因学意义

大别山地区的主薄原，天柱山，白马尖三个花岗岩体主要由花岗闪长岩和二长花岗岩组成，岩石为准铝质到弱过铝质（ACNK＝0．78－1．05），为轻稀土富集型，富含大离子亲石元素Rb,Th，以及稀土元素La,Ce,Nd,Sm，通过花岗岩地质学，岩石学和地球化学研究，认为这在个岩体的地球化学特征相似，属I型花岗岩，其构造背景为碰撞后环境。     

国外^129I在水文地质中应用综述

本文讨论了~(129)Ⅰ的三个起源:大气起源、地下起源和人工起源,通过三个实例,介绍了~(129)Ⅰ在石油勘探、水文地质研究和环境监测中的应用进展,并且指出了未来研究方向。     

碱性红13分光光度法测定氰化物浸出液中金(Ⅰ)的研究及应用

本文研究和确定了碱性红13显色、乙酸异戊酯萃取光度法,直接测定氰化物浸出液中金(I)的条件和方法。Au(CN)_2离子与显色剂形成1:1的离子缔合型配合物被乙酸异戊酯萃取,在有机相中至少稳定22h,配合物在540nm波长处有最大吸收,表观摩尔吸光系数ε_((?)40)=4.4×10~4L·mol~(-1)·cm~(-1)。金含量在0～20ug/5ml乙酸异戊酯范围内符合比尔定律。方法具有简便、快速、重现性好、毒性较小、成本低、实用性较强等优点,用于金矿浸出液的分析,结果令人满意。     

多摄站系统质量分析及其法方程病态现象的克服

本文介绍了一个多摄站（全方位）摄影测量系统，它适宜于近景摄影测量灵活的构网形式，包括全方位摄影，文中分析了多摄站摄影测量网平差的精度和可靠性，并介绍一种该系统试用的克服法方程病态现象的新方法。     

南票热变煤中不溶有机质的谱学研究

通过对南票热变煤的Ⅰ·Ｒ、Ｒｏｃｋ—ｅｖａｌ与ＸＲＤ的研究，对其成煤母质、煤级、矿物与热变煤的物理化学结构演化等方面有了新的认识：该煤生成有低等生物参与；煤脱矿作用使脂肪结构优先低温氧化，煤中矿物对Ｓ２峰影响较大；Ｔｍａｘ、ＴＰＩ、ＯＰＩ、ｄ００２、Ｌｃ等为较好的成熟度参数，而ＨＩ、Ａ因子、Ｃ因子、脂芳比受成熟度与母质双重因素影响；ｄ００２、Ｌｃ与温度和有机质受热速度有关；镜质体反射率主要取决于稠环芳香结构规整程度；Ｌａ、Ｌｃ下降与Ｌａ／Ｌｃ＞１是热变煤特征；热变煤的物理化学结构演化类似区域变质煤。     

湖南古丈山体滑坡影响因子分析

为研究湖南省古丈县2016年7月17日群体滑坡的地质环境与降水诱发成因,基于GIS空间分析平台,利用古丈县1:5万地质灾害详查资料、地形地貌、公路河网、坡度坡向、地下水类型、滑坡体与岩土产状关系等空间数据,分析古丈县多种地质环境因子与滑坡事件的影响系数;采用贝叶斯后验概率分析法确定古丈滑坡降水阈值曲线(I-D曲线);基于多要素地质环境因子、临界降水条件及滑坡触发有效雨量综合分析了本次群体滑坡事件的主要成因。结果表明:出现大于当地滑坡阈值的极端降水事件(一定的滑坡降水强度、持续时间和滑坡触发有效雨量)是诱发古丈群体滑坡的主要外源动力,脆弱的岩土结构、滑坡体与岩层产状一致的滑坡类型、公路(铁路)和河网修建对山体切坡的影响、敏感的坡度区间、高风险的坡向区间等地质因子是导致古丈默戎"7·17"滑坡的地质成因,相关研究方法和结论对该地区未来地质灾害预警预报提供了方法和数据支持。     

地理栅格数据并行I/O的研究与实现

随着遥感和测绘技术的进步,日益增大的数据量和高效的数据I/O矛盾逐渐凸显。本文针对这个问题提出了地理栅格数据的一种并行I/O模式,并对该I/O模式进行了相应的编程实现。通过设计实验验证其正确性和效率,我们发现相比传统的栅格数据I/O库（GDAL库）而言,采用本文提出的并行I/O模式对应的I/O库将能同时保证结果的正确性和高效性。     

The Politics of the Map in the Early Twentieth Century

Drawing on material from several countries, principally Britain, France, and the United States, this paper considers the politics of mapmaking in the years before, during, and immediately after World War I. Following a discussion of some noteworthy but hitherto overlooked mapping projects from the period around 1900, the paper examines the wartime production of maps as aids to geopolitical strategy in three Allied cities—London, Paris, and New York—with particular reference to the major geographical societies in these locations.