透岩浆流体作用与矿田构造

从透岩浆流体成矿理论的角度对矿田构造进行了重新认识,提出矿田构造系统是一种复杂性动力系统的观点。根据这个模型,矿田构造是近场应力场与远场应力场强烈相互作用的产物。近场应力场由岩浆成矿系统而不是远场应力场派生,因而不能由矿田构造反演区域构造,但可以从区域构造限定矿田构造。矿田构造常有岩脉和热液脉充填,因而是可识别的。利用构造统计学方法,可以根据岩脉和/或热液脉的分布密度图(或等值线图)预测找矿靶区。     

基于分形方法的蚀变矿物多尺度特征分析

针对矿化蚀变信息常常受其他地物信息的干扰与影像空间分辨率的制约而表现得非常微弱的问题,该文以Landsat7号ETM+30m空间分辨率的影像为数据基础,重采样得到一系列不同空间分辨率的影像;运用ETM+波段3/波段1比值法获得铁染蚀变相对含量灰度图,采用分形模型计算出不同分辨率下蚀变矿物的分维值,进而获得分辨率—分维值的一元线性回归方程;最后建立了基于分形理论的蚀变矿物多尺度分析模型,得到蚀变矿物空间分布特征变化的参考尺度。结果表明,在一定尺度范围内(30~280m),蚀变矿物显示出空间尺度特征。     

ComGIS在阿克苏地区矿产资源数据库管理系统建设中的应用

采用ComGIS技术,SuperMap二次开发平台,利用可视化开发工具C#与SuperMap Object提供的控件、工具、对象库相结合的具体开发模式,设计开发了阿克苏地区矿产资源数据库管理系统。并利用GIS实现了矿产资源数据库基础数据的建设。     

ZY-102C星数据在矿山遥感监测中的应用研究与分析

利用资源一号(ZY-1)02C卫星(以下简称02C星)全色高分辨率相机(HR)和多光谱相机(MUX)数据,以河北承德多金属矿区和江西寻乌稀土矿区为实验区,开展了1∶5万矿山遥感监测应用研究;分析了应用过程中存在的问题,提出了解决方案和建议,对02C星数据在矿山遥感监测中的规模化应用起到了示范效果。研究结果表明:在数据处理流程上,对空间分辨率为2.36 m的02C星全色HR1与HR2数据需先进行正射纠正再拼接,对空间分辨率为10 m的多光谱数据MUX可采用假彩色合成方法进行模拟真彩色合成;在矿山地物识别上,与SPOT5图像比较,02C星图像可更好地反映出开采面、开采点、中转场和矿山建筑等矿山地物类型,不足之处是纹理信息较平滑、矿山地物的边界相对模糊,因而增加了室内解译的难度;在经济效益上,02C星数据的性价比优势明显。因此,尽管02C星数据处理和解译工作量较大,但其能满足1∶5万矿山遥感监测要求,总体经济效益显著。     

深部细粒碎屑岩储层成岩作用研究——以苏北盆地张家垛油田阜三段为例

毗邻烃源岩的细粒储层,由于其岩石结构、组分及沉积环境的特殊性,成岩作用表现出一定差异。本文以张家垛油田阜三段细粒碎屑岩储层为例,通过铸体薄片、X射线衍射、扫描电镜等相关分析,研究其成岩作用的特殊性。研究结果表明:(1)细粒储层的成分成熟度和结构成熟度较高,常被泥岩包裹,在压实作用中若存在欠压实,粒间孔可以被很好地保留下来;(2)细粒储层形成时水动力较弱,杂基含量高导致微孔较多;(3)大量的粘土矿物使孔隙比表面增加,抑制了后期硅质和碳酸盐胶结物的析出;(4)比表面的增加减缓了孔隙流体的对流速率和扩散速率,不利于次生孔隙的形成,粒度越细,次生孔隙越不发育。细粒碎屑岩储层有别于常规储层,对其特殊的成岩作用进行研究具有重要的理论价值和实际意义。     

Simulation of the Direct Radiative Effect of Mineral Dust and Sea Salt Aerosols in a Doubled Carbon Dioxide Climate

The authors examine the equilibrium climatic response to the direct radiative effect(DRE)of mineral dust and sea salt aerosols in a doubled-CO2climate with two-way coupling of aerosol-climate interactions.In response to the drier and windier conditions,dust emissions increase by 26%in the Sahara Desert and by 18%on the global scale relative to present day.Sea salt emissions increase in high latitudes(60°)but decrease in middle latitudes(30°–60°)of both hemispheres due to the poleward shift of westerlies,leading to a 3%decrease in global emissions.The burdens of dust and sea salt increase by 31%and 7%respectively,because reductions in rainfall over the tropical oceans increase the lifetime of particles in the warmer climate.The higher aerosol loading in the doubled-CO2climate reinforces aerosol DRE by0.2 W m 2,leading to an additional cooling of 0.1°C at the surface compared with the climatic effects of aerosols in present day.The additional cooling from changes in natural aerosols compensates for up to 15%of the regional warming induced by doubled CO2.     

Temporal and spatial variability of cation and silica export in an alpine watershed,Emerald Lake,California

A reaction set of possible mineral weathering reactions is proposed to explain observed cation and silica export for the Emerald Lake watershed, a small Sierra Nevada, California catchment. The reaction set was calculated through a stoichiometric mole‐balance method, using a multiyear record of stream flow and snowpack chemical analyses and site‐specific mineral compositions. Reaction‐set calculations were intended to explore how the processes controlling stream cation and silica export depend on differing bedrock mineralogy across the catchment as snowmelt and runoff patterns change over the year. Different regions within the watershed can be differentiated by lake inflow subdrainages, each exhibiting different stream‐flow chemistry and calculated weathering stoichiometry, indicating that different silica and cation generation processes are dominant in wet steep portions of the catchment. Short‐term differences in stream concentrations were assumed to reflect ion exchange equilibria and rapid biological processes, whereas long‐term persistent stream concentration differences in different areas of the catchment were assumed to reflect spatial variability in mineral weathering stoichiometry. Mineralogical analyses of rock samples from the watershed provided site‐specific chemical compositions of major mineral species for reaction calculations. Reaction sets were evaluated by linear regression of calculated versus observed differences between snowmelt and stream‐flow chemistry and by a combined measure. Initially, single weathering reactions were balanced and evaluated to determine the reactions that best explained observed stream chemical export. Next, reactions were combined, using mineral compositions from different rock types to estimate the dependence of ion fluxes on lithology. The seasonal variability of major solute calculated fluxes is low, approximately one order of magnitude, relative to the observed three orders of magnitude variability in basin discharge. Reaction sets using basin‐averaged lithology and Aplite lithologies gave superior explanations of stream chemical composition. Copyright © 2004 John Wiley & Sons, Ltd.     

Contrasting mineral isograd sequences in metabasites of the Cape Smith Belt, northern Québec, Canada: three new bathograds for mafic rocks

Regional-scale mapping of index-mineral isograds in mafic units of the early Proterozoic Cape Smith Thrust Belt (northern Québec) has revealed contrasting pressure-temperature regimes associated with two distinct structural domains. In the southern domain, crustal thickening was accomplished by early, piggy-back thrust faults. Isograds cross-cut the thrusts, indicating that thermal-peak mineral growth outlasted deformation associated with early imbrication. Mineral zones are: (1) actinolite (Act) + albite (Alb); (2) hornblende (Hbl) + Act + Alb; (3) Hbl + Act + oligoclase (Oli); (4) Hbl + Oli; and (5) garnet (Grt) or clinopyroxene + Hbl + Oli-andesine. The oligoclase isograd occurs at higher grade than the hornblende isograd, a sequence typical of medium-pressure terranes (5–7 kbar). An Hbl-Alb bathograd. calibrated from mixed-volatile equilibria in the NCMASH-CO₂ model system, suggests minimum pressures of about 5.4 kbar. Metamorphism in the northern domain was a consequence of re-imbrication, by means of out-of-sequence thrust faults active during and after peak metamorphic conditions. Mineral growth was coeval with thrusting, as documented by the syn-kinematic garnet porphyroblasts. Compared to the southern domain, a different sequence of isograds in mafic rocks shows that the albite-oligoclase transition takes place in the garnet zone. Based on thermobarometry in garnet-hornblende rocks, the oligoclase isograd occurs in a temperature range of 525–600°C, typical of high-pressure terranes (7–10 kbar). Calibrated bathograds for the Hbl-Ms-Alb and Grt-Alb bathozonal assemblages, respectively in the KNCMASH-CO₂ and NCMASH model systems, indicate minimum pressures in the northern domain of 6.7 and 8.5 kbar. Higher-pressure series for this domain are explained by out-of-sequence thrusts exposing deeper crustal levels. For similar structural levels, only minor amounts of syn-deformational uplift (1–2 kbar and 50–75°C) are recorded in metabasites of this domain, compared to results in adjacent metapelites of the area (essentially isothermal uplift of 3–5 kbar). RESUME La bande du Cap Smith (nord du Québec) est une ceinture de chevauchement d'ǎge protérozoique inférieur, dominée par des roches mafiques. La cartographie d'isogrades à minéraux indicateurs dans les unités mafiques de la ceinture a révelé deux régimes contrastes de pression–température, chacun associéà des épisodes distincts d'épaississement crustal. Dans le domaine sud, des failles de chevauchement en-série sont responsables pour l'empilement tectonique. Les isogrades recoupent les failles, indiquant que l'apogée thermale a suivi l'emplacement initial des nappes de charriage. Les zones minérales sont: (1) actinote (Act) + albite (Alb); 2) hornblende (Hbl) + Act + Alb; (3) Hbl + Act + oligoclase (Oli); 4) Hbl + Oli; et (5) grenat (Grt) où clinopyroxene + Hbl + Oli-andésine. L'isograde d'oligoclase apparaǐt à plus haute température que l'isograde d'hornblende, une séquence typique des terrains de pressions moyennes. Un bathograde Hbl–Alb, calibréà partir d'équilibre mixte de volatiles dans le système NCMASH–CO₂, suggère des pressions minimales d'environ 5.4 kbar. Le métamorphisme dans le domaine nord de la ceinture a été le résultat d'une réimbrication, causé par des chevauchements hors-série actifs pendant et après l'apogée thermale. La croissance minérale fǔt synchrone au chevauchement, documentée par des porphyroblastes de grenat syn-cinénatique. Comparé au domaine sud, une différente séquence d'isogrades dans les métabasaltes montre que la transition albite–oligoclase se situé dans la zone à grenat. Par la thermobarométrie dans les roches à grenat–hornblende l'isograde d'oligoclase se situe dans un écart de température de 525–600°C, typique des terrains de hautes pressions (7–10 kbar). Des bathogrades calibrés pour les assemblages bathozonales Hbl–Ms–Alb et Grt–Alb, rcspectivement dans les systèmes KNCMASH–CO₂ et NCMASH, indique des pression minimales pour le domaine nord de 6.7 et 8.5 kbar. Une zonégraphie à plus haute pression pour ce domaine est expliquée par des chevauchements hors-série exposant des niveaux plus inférieurs de la croǔte imbriqué. Pour des niveaux structuraux similaries, des soulèvements syn-métamorphiques mineurs sont enregistrés dans les métabasaltes (1–2 kbar et 50–75°C), comparés aux métapélites adjacentes avec un soulèvement (essentially isothermal uplift of 3–5 kbar.     

Petrographic, Chemical and B-Isotopic Insights into the Origin of Tourmaline-Rich Rocks and Boron Recycling in the Martinamor Antiform (Central Iberian Zone, Salamanca, Spain)

Tourmaline in the Martinamor antiform occurs in tourmalinites(rocks with >15–20% tourmaline by volume), clasticmetasedimentary rocks of the Upper Proterozoic Monterrubio formation,quartz veins, pre-Variscan orthogneisses and Variscan graniticrocks. Petrographic observations, back-scattered electron (BSE)images, and microprobe data document a multistaged developmentof tourmaline. Overall, variations in the Mg/(Mg + Fe) ratiosdecrease from tourmalinites (0·36–0·75),through veins (0·38–0·66) to granitic rocks(0·23–0·46), whereas Al increases in thesame order from 5·84–6·65 to 6·22–6·88apfu. The incorporation of Al into tourmaline is consistentwith combinations of ^xAl(NaR)_–1 and AlO(R(OH))_–1exchange vectors, where ^x represents X-site vacancy and R is(Mg + Fe²⁺ + Mn). Variations in ^x/(^x + Na) ratios are similarin all the types of tourmaline occurrences, from 0·10to 0·53, with low Ca-contents (mostly <0·10apfu). Based on field and textural criteria, two groups of tourmaline-richrocks are distinguished: (1) pre-Variscan tourmalinites (probablyCadomian), affected by both deformation and regional metamorphismduring the Variscan orogeny; (2) tourmalinites related to thesynkinematic granitic complex of Martinamor. Textural and geochemicaldata are consistent with a psammopelitic parentage for the protolithof the tourmalinites. Boron isotope analyses of tourmaline havea total range of ¹¹B values from –15·6 to 6·8;the lowest corresponding to granitic tourmalines (–15·6to –11·7) and the highest to veins (1·9to 6·8). Tourmalines from tourmalinites have intermediate¹¹B values of –8·0 to +2·0. The observedvariations in ¹¹B support an important crustal recycling ofboron in the Martinamor area, in which pre-Variscan tourmaliniteswere remobilized by a combination of mechanical and chemicalprocesses during Variscan deformation, metamorphism and anatexis,leading to the formation of multiple tourmaline-bearing veinsand a new stage of boron metasomatism. KEY WORDS: tourmalinites; metamorphic and granitic rocks; mineral chemistry; whole-rock chemistry; boron isotopes     

The importance of mineral and energy inventories

Based on the results of the Conference on Resource Assessment Techniques of IGCP Project 98 in Loen, Norway, 1976, the importance of mineral and energy inventories is demonstrated by their long-term objectives which aim at the solution of problems of quantitative and qualitative mineral and energy reserve and resource assessments, estimates of the exploration potential, supply analysis, future land-use planning, and national mineral policy. Prior to establishing a mineral and energy inventory it is essential to clearly define both the long-term and short-term objectives, because they control the scope of an inventory and determine the approach to and the method of constructing the data base. Only then can questions be answered as to the kind of data required, the advantages of regional-versus commodity-based inventories, the necessity of computer-processable data files, the availability of a user-oriented data base management system, and the usefulness of conducting a pilot project. Examples are given for simple and complex types of mineral and energy inventories. The “Mineral Deposit Inventory” of the Institute for Geosciences and Natural Resources, Hannover, Federal Republic of Germany, serves mainly as an information and reference system, whereas the mineral inventory of “Project Manitoba” of the Geological Survey of Canada forms the base for reserve and resource assessment as well as land-use planning of that province. For developing and industrialized countries alike, mineral and energy inventories are appropriate tools in planning new exploration activities and decisions on future national mineral policy. Used by the Regional Mineral Resources Development Centers of ESCAP and ECA, the United Nations economic commissions in Asia and Africa, these tools could be of great advantage and mutual benefit to the developing countries of those regions. This paper was presented at the International Geological Correlation Program (IGCP) Project 98: “Standards for Computer Applications in Resource Studies” held at Taita Hills, Kenya, November 8–15, 1977.