硅硼镁铝矿复杂（高次）孪晶的微结构研究

本文用透射电子显微技术研究了硅硼镁铝矿的显微结构特征。研究结果表明:该矿物发育复杂(高次)生长孪晶,即(202)孪晶,(280)(202)二次孪晶,(04I)(280)(202)三次孪晶和(443)四次孪晶。并阐明了矿物高次孪晶的相互结构关系。同时,在TEM明场象中观察到了该矿物复杂孪晶对应的结晶形态。笔者还总结了低对称复杂孪晶显微结构的分析方法。     

波—流相互作用机制与复合流的沉积构造鉴别标志*

波—流相互作用是复杂水动力条件下流体相互作用的主要方式之一,由波—流相互作用形成的复合流沉积是目前沉积学在流体相互作用这一领域研究较多的一种沉积类型。以已有的文献为基础,对波—流相互作用下细砂级颗粒的运动机制进行了综述,预测了波—流相互作用的沉积特征,总结了复合流的沉积构造鉴别标志。取得的主要认识有: (1)波—流相互作用总体上属于衰弱流(waning flow)悬浮沉积,其微观的沉积机制可分为5种: 越过崩落点的喷射沉积(S1)、残余涡动沉积(S2)、未到崩落点的喷射沉积(S3)、背流面的崩落沉积(S4)、垂直降落沉积(S5);(2)波—流相互作用的沉积过程总体上受悬砂量和沉积时间的控制,5种微观沉积机制在不同的悬砂量和沉积时间条件下可形成不同的沉积机制组合,从而导致不同的底床形态;(3)复合流沉积构造鉴别标志主要有: 复合流波痕、复合流层理、爬升型复合流层理、不对称丘状交错层理、准平行层理和频繁交替的不能充分发育的浪成波纹层理与流水层理等6类。上述认识对于复杂水动力条件下的沉积学研究及对深水、浅水沉积环境的识别均具有重要的意义。     

花岗岩力学特性的温度效应试验研究

通过实时高温（常温～850 ℃）加载和高温（常温～1 200 ℃）后冷却再加载两种情况下的单轴压缩试验,对不同高温下花岗岩的力学性质进行了研究,分析了两种情况下单轴抗压强度、弹性模量、纵波波速、剪切滑移应变等随温度的变化规律,并研究了热-力耦合效应。研究结果表明：（1）在实时高温加载作用下单轴抗压强度和弹性模量随着温度升高而发生连续劣化;（2）高温作用冷却后再加载,花岗岩在常温～600 ℃区间峰值强度变化不大,800 ℃左右岩样强度突然降低;（3）纵波波速随加热温度的升高而逐渐降低;（4）剪切滑移应变在800 ℃之前相对较小,且变化不大,之后便迅速增大,表现出明显的塑性;（5）提出了热-力耦合因子的概念,并借助其提出了一维非线性热-力耦合本构模型,模型曲线和试验曲线较吻合。     

Estimation of proportions of lithotypes using auxiliary information

The problem of estimating the proportion of lithological (ore) types in volumes of mineral deposits is considered when an auxiliary variable Z(z) is observed along with the lithology L(x) at x. The process {Z(x)} is assumed to be stationary and an assumption on the statistical relationship between {Z(x)} and {L(x)} processes is made. Consequently, the second-order stationarity of {L(x)} is not required. A method using the kriged distribution of the auxiliary variable is proposed. A case study illustrating the procedure is given.     

The comparison of the performance of ELM,BRNN, and SVM methods for the prediction of compression index of clays

The compression index (Cc) is a necessary parameter for the settlement calculation of clays. However, determination of the compression index from oedometer tests takes a relatively long time and leads to a very demanding experimental working program in the laboratory. Therefore, geotechnical engineering literature involves many studies based on indirect methods such as multiple regression analysis (MLR) and soft computing methods to determine the compression index. This study is aimed to predict the compression index by using extreme learning machine (ELM), Bayesian regularization neural network (BRNN), and support vector machine (SVM) methods. The selected variables for each method are the natural water content (w_n), initial void ratio (e₀), liquid limit (LL), and plasticity index (PI) of clay samples. Many trials were carried out in order to get the best prediction performance with each model. The application results obtained from the models were also compared based on the correlation coefficient (R), coefficient of efficiency (E), and mean squared error (MSE). The results indicate that the BRNN method has better success on estimation of the compression index compared to the ELM and SVM methods.     

高岭石对重金属离子的吸附机理及其溶液的pH条件

高岭石对Cu^2+,Pb^2+离子的吸附实验及高岭石的溶解实验表明,高岭石对重金属离子的吸附有别于石英单一表面配位模式,离子交换和表面配位模式并存,并随溶液pH由酸性往碱性的变化发生规律性的演替：pH<6.5时主要表现为外圈层配位的离子交换吸附,且在pH<4时由于受到高岭石表层中铝的高溶出及溶液中较高离子强度的影响,高岭石对Cu^2+,Pb^2+离子的吸附率较低,pH为5～6时由于高岭石端面的荷电性为近中性,吸附率则有明显的提升并且表现为一个吸附平台;pH>6.5时离子交换和表面配位均为重要吸附机制,pH再升高时沉淀机制则起着重要作用。研究表明,pH调控高岭石-水界面溶解与质子化-去质子化反应过程,并影响着Cu^2+,Pb^2+离子的吸附行为。最后采用Sverjensky(1993)表面配位的物理模型对吸附结果作了描述。     

The effect of maturation on the configuration of pristane in sediments and petroleum

The absolute stereochemistry of pristane in a sample of contemporary marine Zooplankton, Messel shale (Germany) and Djatibarang (Java) crude has been determined by gas Chromatographic methods. The relative stereochemistry in Irati shale (Brazil), Green River (U.S.) crude, Halibut (Australia) crude has also been determined, and confirmed for a sample of the Green River shale. The stereoisomer distributions indicate a loss of stereospecificity of the phytol-derived 6(R),10(S) pristane with increasing geological maturation. For example, the least mature geological sample, the Eocene Messel shale, contains solely the 6(R),10(S) isomer, whereas a mature sample, Djatibarang crude, contains 50% of the 6(R),10(S) isomer and 25% of each of the 6(R),10(R) and 6(S),10(S) isomers.     

氟碳铈矿U-Pb定年技术研究

本文以稀土矿床中的常见副矿物氟碳铈矿为研究对象,通过优化实验条件和仪器参数,分别采用激光剥蚀多接收电感耦合等离子体质谱法(LA-MC-ICP-MS)和同位素稀释热电离质谱法(ID-TIMS)对氟碳铈矿样品SAM进行U-Pb定年技术研究,并将此两种方法得到的结果进行对比。LA-MC-ICP-MS得到的U-Pb年龄为(409±18)Ma(N=27,MSWD=4.5),ID-TIMS得到的206Pb/238U U-Pb年龄为(407.8±3.3)Ma(N=3,MSWD=0.029),两种方法得到的U-Pb年龄结果在误差范围内一致。通过比较两种方法的实验流程和结果,总结了各自的优缺点,为氟碳铈矿U-Pb定年方法选择提供了参考依据。     

A study of the rate of gypsum leaching from the pore space of sandstones

Experimental studies of the rate of gypsum leaching from the pore space in sandstone revealed a zone with higher dolomite content (due to dolomitization of calcite in the peripheral region of the block), with minimum values of gypsum content and maximum ones of total porosity. It is shown that leaching from rock blocks in the near-shore zone of the Kafirnigan (Kofarnihon) River is defined by two successive stages: (1) leaching of the dolomitization zone (the slowest) and (2) from the field with background values of dolomite and calcite (fast). The average value of the coefficient of diffusion for Ca²⁺ ions in the second region is higher by ~70% than in the first one.     

Review of Microstructural Evidence of Magmatic and Solid-State Flow

Evidence of magmatic flow includes: (a) parallel to sub-parallel alignment of elongate euhedral crystals (e.g., of feldspar or hornblende) that are not internally deformed, (b) imbrication (‘tiling’) of elongate euhedral crystals that are not internally deformed, (c) insufficient solid-state strain in regions between aligned or imbricated crystals to accommodate phenocryst rotation, (d) elongation of microgranitoid enclaves without plastic deformation of the minerals, (e) magmatic flow foliations and elongate microgranitoid enclaves deflected around xenoliths, and (f) schlieren layering (if due to flow sorting) in the absence of plastic deformation of the minerals involved. These features are consistent with rotation of crystals in a much weaker medium, namely a melt phase, at a stage when the magma has become viscous enough to preserve the alignment.Evidence of solid-state flow includes: (a) internal deformation and recrystallization of grains, (b) recrystallized “tails,” (c) elongation of recrystallized aggregates (e.g. of quartz and mica), (d) grainsize reduction, (e) fine-grained folia anastomosing around less deformed relics, (f) microcline twinning, (g) myrmekite, (h) flame perthite, (i) boudinage of strong minerals, typically with recrystallized aggregates of weaker minerals (e.g. quartz and mica) between the boudins, (j) foliation passing through, rather than around enclaves, and (k) heterogeneous strain with local mylonitic zones.Several criteria suggest “submagmatic flow,” including recrystallized feldspar, inferred transitions from magmatic imbrication to solid-state S/C arrangements, evidence of c-slip in quartz, and especially evidence of migration of residual melt into lower-pressure sites.Recent experimental studies indicate that a change from grain-supported flow to suspension flow typically occurs in deforming magmas at melt contents of between 20% to 40%, and that large amounts of strain may accumulate in magmas without being recorded by the final fabric. At lower melt percentages, perhaps as low as a few percent, depending on the minerals and their shapes, strain may be accommodated by: (a) melt-assisted grain-boundary sliding, (b) contact-melting assisted grain-boundary migration, (c) strain partitioning into melt-rich zones, (d) intracrystalline plastic deformation (c-slip in quartz indicating plastic deformation at temperatures near the granite solidus), and (f) transfer of melt to sites of low mean stress. The only indication of strain in the absence of crystal plasticity may be an alignment of crystals. Moreover, magmatic flow microstructures may be destroyed by fracturing, crystal plasticity and recrystallization before the magma reaches its solidus.Many rocks show evidence of solid-state flow superimposed on magmatic flow. Evidence of magmatic flow is commonly preserved in deformed felsic metamorphic rocks: for example the alignment of rectangular K-feldspar megacrysts and of microgranitoid enclaves. However, absence of alignment does not preclude a magmatic origin for K-feldspar megacrysts in felsic gneisses, as magmatic flow may cease before the magma becomes viscous enough to preserve an alignment.     

群桩效应有限元分析

利用有限元方法,对竖向荷载作用下复合桩基的群桩效应进行了计算分析,讨论了桩长L、桩距与桩径之比Sa/d、桩数n、土类等对群桩效应及群桩效应系数η的影响。结果表明：复合桩基中各个基桩的极限承载力Qu及η随L增大而增大;当Sa/d小于某个数值时,Qu,η随Sa/d增大而增大;当Sa/d大于某个数值时,Qu,η随Sa/d增大而减小。群桩效应及η与土类有关;η存在极大值,随n增多而减小,但减幅不大。     

Elemental characterization of black shales of Khyber Pakthunkhawa (KPK) region of Pakistan using AAS

Black shale samples were collected from Chimiari Khyber Pakthunkhawa region of Pakistan and were analyzed for elemental compositions. Atomic Absorption Spectrophotometry (AAS) was utilized for the determination of elements in the digested solutions. The analysis of black shale was performed precisely with relative standard deviation (RSD) lower than 2%. Results showed that the samples contained high concentrations of Ca (11.98 %), Al (7.09%), Fe (3.03%), Mg (0.59%) and Ti (0.58%).     

Scaling properties of landslides in the Rif mountains of Morocco

Landslides in the central Rif mountains (Morocco) were analyzed by multifractal analysis. Our results suggest that spatial distribution of landslides in the region is not a homogeneous fractal structure but a heterogeneous one with generalized dimensions D(1)=1.713>D(2)>…>D(12)=1.325. The value of D(12)=D(∞) is the fractal dimension of the most intensive clustering in the heterogeneous fractal set. It is worthwhile to note that we found D(0)<D(1). The analysis of areas affected by sliding from the geological map of Beni Ahmed at a scale 1:50 000 shows the power law size distribution: N(A>a)∝a^−1.57. This confirms the scale invariance of sliding and suggests that real landslides may exhibit a Self-Organized Criticality (SOC) behaviour.     

Metamorphism of the Crystalline Basement of Central Chile

The metamorphic basement of the Cordillera de la Costa, in CentralChile, consists mainly of slate, meta-sandstone, phyllite, andmica schist but contains small quantities of greenschist. Thegreater part of the basement is comprised in the Curepto series,and is characterized by dynamo-metamorphism whose intensityincreases westward. East of this is the smaller Nirivilo series,characterized by contact metamorphism whose intensity increaseseastward toward a granodiorite batholith. At the northern endof the metamorphic belt lies the Pichilemu series, in whichthe metamorphism is dynamo-thermal and increases in intensityto the east. The rocks in the first two areas are divisibleinto zones that trend north-north-east, essentially parallelto the margin of the batholith and to the Pacific coast; butin the Pichilemu area the zoning trends north-west. In the Cureptoseries three zones were distinguished; these are, in order fromeast to west: (1) a muscovite-chlorite(-albite) slate zone,(2) a muscovite-biotite(-albite) phyllite zone, and (3) a muscovite-chlorite-albite(±garnet) schist zone. The rocks in all three zones belongto the greenschist facies; the chlorite in the third zone isbelieved to be a product of H metasomatism. In the much narrowerNirivilo area no zones were mapped, but the following eastwardsuccession of critical assemblages was recognized: (1) muscovite-biotite-chlorite-albite;(2) muscovite-biotite-chlorite-andalusite-albite; (3) biotite-muscovite-andalusite-oligoclase;(4) biotite(± muscovite)-andalusite-sillimanite (or cordierite).The muscovite in the rocks that have undergone highgrade metamorphismis largely of metasomatic origin. Part of the sillimanite hasbeen formed at the expense of biotite and andalusite. In mostof the Nirivilo area the most strongly metamorphosed rocks areof the hornblende-hornfels facies, but small parts of that areamay contain rocks of the pyroxene-hornfels facies. The Pichilemuarea comprises the following zones and subzones: (1) a biotitezone, which includes (a) a muscovite-chlorite-biotite-albitesubzone and (b) a muscovite-biotite-albite subzone; (2) a garnet-oligoclasezone; (3) a staurolite-andalusite zone; (4) a muscovite-sillimanitezone; and (5) a sillimanite-orthoclase zone which includes (a)a sillimanite-orthoclase subzone and (b) a sillimanite-orthoclase-cordierite-almandinesubzone. Some thermal metamorphism is superimposed on the regionalmetamorphism. The facies grade from the greenschist to the granuliteor intermediate between the granulite and the amphibolite facies.The three series represent different pressure conditions: theNirivilo series corresponds to a low-pressure (contact) type,Pichilemu represents a low-pressure intermediate, dynamo-thermaltype, and Curepto is a dynamothermal, high-pressure intermediatetype series. The Curepto area was affected first, the Pichilemuarea next, and the Nirivilo area last. The metamorphism in allthree series is thought to have occurred during a single tectoniccycle within Late Paleozoic time, but it was probably interruptedby periods of erosional unloading. The width of the contactaureole is thought to have been determined by the irregularexpansion of the batholith. The analogy between the metamorphicseries of the Cordillera de la Costa and Miyashiro's circum-Pacificpaired belts is briefly discussed.     

吉林省中部晚三叠世—早侏罗世火山事件地层划分刍议

根据不同比例尺的区域地质调查成果以及综合研究资料,吉林省中部早中生代火山事件地层可初步作如下划分:晚三叠大酱缸组沉积期自早而晚有:星星哨火山事件(229.5～227.5 Ma),官马火山事件(222±10)Ma,西土山火山事件(210±19)Ma;早侏罗世板石顶子组沉积期有:双丫子东山火山事件(195.04±5.01)Ma,官马金矿火山事件(193.6 Ma);早侏罗世太阳岭组沉积期有:未命名火山事件1(188.0±19.0)Ma,未命名火山事件2(184.0±1.1)Ma,北大湖火山事件(179.4±1.1)Ma,二道沟火山事件(174.0±34)Ma。     

Structural evidence of the age of folded rocks on the south coast of New South Wales

The pre‐Devonian sedimentary and volcanic sequence exposed along the south coast of New South Wales has previously been divided into three stratigraphic groups: (1) Upper Ordovician graptolite‐bearing slate which is conformable with (2) interlayered thinly‐bedded greywacke and pelite of undifferentiated Ordovician age and (3) Cambrian successions of interlayered chert, pelite and volcanic rock at Bate‐mans Bay and Narooma. The main bases for this subdivision are a change in rock types between (1) and (2), and the unconformity between (2) and (3) formerly proposed on the basis of changes in rock type and fold style across the boundary. New structural data are presented which refute the presence of the unconformity, and conformity of (2) and (3) with the fossiliferous slates is established.     

长江中下游地区九瑞矿集区邓家山花岗闪长斑岩的地球化学与成因研究

邓家山是长江中下游成矿带九瑞矿集区西北部的一处矽卡岩型Cu-Au-Mo矿床.矿区与成矿关系密切的岩体为花岗闪长斑岩.本文通过锆石SHRIMP U-Pb定年确定,该岩体侵位于早白垩世早期(138.2±1.8Ma).常微量元素分析结果表明,邓家山花岗闪长斑岩具有埃达克质岩的地球化学特征,表现为高Sr(＞650×10~(-6))、Ba(＞700×10~(-6)),低Y(＜12×10~(-6)),Yb(＜1×10~(-6)),Nb(＜10×10~(-6)),Ta(＜0.7×10~(-6)),富集轻稀土而强烈亏损重稀土(LREE/HREE=12.2～13.5).邓家山花岗闪长斑岩的~(87)Sr/~(86)Sr,为0.7068～0.7071,ε_(Nd)(t)为-2.7～-2.3,Nd同位素两阶段模式年龄T_(2DM)为1.13Ga～1.15Ga.锆石的Hf同位素分析结果表明,~(176)Ht/~(177)Hf值为0.282475～0.282539,计算的ε_(Hf)(t))值为-5.2～-7.5,Hf同位素两阶段模式年龄T2DM为1.52Ga～1.67Ga.全岩ε_(Nd)(t)与锆石ε_(Hf)(t))之间出现了较为明显的Nd-Hf同位素解耦.根据以上特征,我们认为邓家山花岗闪长斑岩是壳幔相互作用的产物,即增厚下地壳拆沉并部分熔融,岩浆在上升过程中又与地幔橄榄岩发生大规模混染.     

Economic aspects of carbonatites of India

Among the 20 carbonatite–alkaline rock associations known from India, eight contain economic deposits that are either being presently exploited or likely to become workable resources. These include deposits of fluorite (Ambadongar, Gujarat), apatite, (Newania, Rajasthan; Kutni and Beldih, West Bengal) and vermiculite (Sevattur, Tamil Nadu). Carbonatite complexes of Sevattur, Sung Valley and Samchampi hold considerable potential for Nb, P, and Fe. The Samchampi Complex, Assam contains an estimated reserve of some 300 million tons of hematite ore, besides Nb (10,970 tons), Ta (3740 tons), Y (1894 tons) and apatite (10 million tons of ore with 35% P₂O₅) and thus appears to be the most promising complex among the new discoveries. Recovery of pyrochlore±apatite, magnetite, zircon, and monazite have been evaluated for the soils at Sevattur, Sung Valley and Samchampi. A variety of elements either alone or in combination such as REE, Ba, Sr, V, Ti, Zr, Th, and U could become important co-products from these complexes.     

The partitioning of copper among selected phases of geologic media of two porphyry copper districts, Puerto Rico

In experiments designed to determine the manner in which copper is partitioned among selected phases that constitute geologic media, we have applied the five-step sequential extraction procedure of Chao and Theobald to the analysis of drill core, soils, and stream sediments of the Rio Vivi and Rio Tanama porphyry copper districts of Puerto Rico. The extraction procedure affords a convenient means of determining the trace-metal content of the following fractions: (1) Mn oxides and “reactive” Fe oxides; (2) “amorphous” Fe oxides; (3) “crystalline” Fe oxides; (4) sulfides and magnetite; and (5) silicates. An additional extraction between steps (1) and (2) was performed to determine organic-related copper in stream sediments.The experimental results indicate that apportionment of copper among phases constituting geologic media is a function of geochemical environment. Distinctive partitioning patterns were derived from the analysis of drill core from each of three geochemical zones: (a) the supergene zone of oxidation; (b) the supergene zone of enrichment; and (c) the hypogene zone; and similarly, from the analysis of; (d) soils on a weakly leached capping; (e) soils on a strongly leached capping; and (f) active stream sediment.The experimental results also show that geochemical contrasts (anomaly-to-background ratios) vary widely among the five fractions of each sampling medium investigated, and that at least one fraction of each medium provides substantially stronger contrast than does the bulk medium. Fraction (1) provides optimal contrast for stream sediments of the district; fraction (2) provides optimal contrast for soils on a weakly leached capping; fraction (3) provides optimal contrast for soils on a strongly leached capping.Selective extraction procedures appear to have important applications to the orientation and interpretive stages of geochemical exploration. Further investigation and testing of a similar nature are recommended.     

Simulation of the geochemical transformations of sterols: superacid effect of clay minerals

The heating of cholestanol 2a with kaolinite (140°C, 16 hr) mainly leads to a mixture of steranes (40%) and sterenes (35%). The major compounds which are formed have been identified as 5α(H)- and 5β(H)-cholestanes, 4a and 4b, the diacholestenes, 5, the diacholestanes, 6, and the D-homodiacholestanes 7. With the exception of the latter, these compounds have all been observed previously in ancient sediments and crude oils. Several of these compounds are identical or bear structural similarities with those obtained from cholestanol at low temperature in acidic or superacidic conditions. The comparison with the results obtained using other minerals (montmorillonite, talc, alumina, polyphos-phate-treated montmorillonite) shows that the observed transformations are catalysed by superacid sites which are present in kaolinite and montmorillonite.