浙江杭嘉湖平原区土壤中营养元素丰缺状况的评价

根据杭嘉湖平原区区域地球化学调查的结果,对本区土壤中农作物营养元素含量及有效量特征进行了评价研究。研究结果表明,本区土壤中营养元素除Mo、S含量表现缺乏外,其它元素为足量和丰富水平。不同土壤中营养元素有效量水平存在明显差异。在区域分布规律上,营养元素的含量及有效量随成土母质、成土过程和人类耕作等因素的不同而显示其差异特征。评价研究结果为本区农业生产中的合理区划、科学施肥、合理种植、土壤改良等提供了重要的地球化学依据。     

高碳黑色页岩型铂族元素矿床性探讨

简析了高碳黑色页岩型铂族元素矿床（PGED）的研究现状，并根据矿床的特征初步将该类矿床划分为中层状黑色页岩，薄层状黑色页岩和高碳构造岩型3类；并从形成环境，成因等方面对PGED形成进行了剖析，强调了源区供给，有机迁移和热液叠加作用的差异是导臻形成不同类型黑色含碳页岩型铂族元素矿床的根源，指出了我国贵州－湖南高碳黑色页岩型铂族元素成矿性较差与层薄和叠加温度低有关。     

Anomalous Enrichment of Silver in Organic Matter of the Songxi Shale-hosted Ag-Sb Deposit in Northeastern Guangdong

The silver contents of organic matter in the host rocks of the Songxi shale-hosted Ag-Sb deposit of northeastern Guangdong, South China, have been directly determined using the electron microprobe technique. The silver contents in two types of organic matter, marine vitrinite and solid bitumen, vary in the range from 100×10-6to 350×10-6, which are from tens of times to thousands of times higher than those of the host rocks in the ore deposit. The average silver content of the organic matter is also several times higher than the pay grade of silver for commercial mining of the ore deposit. It is quite obvious that the organic matter of the host rocks in the ore district is characterized by an anomalous enrichment of silver. The results of this study indicate that the silver anomalies in the organic matter have been derived from both the host rocks and the silver-bearing fluids of the Songxi black shale ore source. In the course of sedimentation and later hydrothermal reworking, organic matter was able     

内蒙古白乃庙金矿断裂构造控矿研究

白乃庙金矿由石英脉型和蚀变岩型金矿组成，并受断裂及其破碎带控制，研究了白乃庙金矿断裂构造与成矿关系，断裂构造趋势面与找矿及矿体在断裂中的富集规律，并对成矿远景进行了预测。     

内蒙古呼伦贝尔盟北部砂金矿成矿规律

呼伦贝尔盟北部地区由于新构造运动含金地质体长期风化剥蚀，促使金的活化。河流及其2－3级支流发育，流域广，水流充足，有利于砂金矿的迁移、富集。现代的乐山丘陵、宽阔沟谷有利于砂金的保存。该区已发现数十个砂金矿，多为河谷型，主要含金层为含粘土砂层或砂砾层。砂金富集与河谷地貌关系密切，河床弯曲的凸岸、变异部位、关门咀、迎门山等地貌是砂金富集有利部位。该区金直接来源于加里东和华力西花岗岩。结合金的来源、矿床的分布特征和富集规律，指出了该区今后砂金找矿方向。     

Characterization of Geochemical Distributions Using Multifractal Models

The use of multifractals in the applied sciences has proven useful in the characterization and modeling of complex phenomena. Multifractal theory has also been recently applied to the study and characterization of geochemical distributions, and its relation to spatial statistics clearly stated. The present paper proposes a two-dimensional multifractal model based on a trinomial multiplicative cascade as a proxy to some geochemical distribution. The equations for the generalized dimensions, mass exponent, coarse Lipschitz–Hölder exponent, and multifractal spectrum are derived. This model was tested with an example data set used for geochemical exploration of gold deposits in Northwest Portugal. The element used was arsenic because a large number of sample assays were below detection limit for gold. Arsenic, however, has a positive correlation with gold, and the two generations of arsenopyrite identified in the gold quartz veins are consistent with different mineralizing events, which gave rise to different gold grades. Performing the multifractal analysis has shown problems arising in the subdivision of the area with boxes of constant side length and in the uncertainty the edge effects produce in the experimental estimation of the mass exponent. However, it was possible to closely fit a multifractal spectrum to the data with enrichment factors in the range 2.4–2.6 and constant K₁ = 1.3. Such parameters may give some information on the magnitude of the concentration efficiency and heterogeneity of the distribution of arsenic in the mineralized structures. In a simple test with estimated points using ordinary lognormal kriging, the fitted multifractal model showed the magnitude of smoothing in estimated data. Therefore, it is concluded that multifractal models may be useful in the stochastic simulation of geochemical distributions.     

High-Mg potassic rocks from Taiwan: implications for the genesis of orogenic potassic lavas

Taiwan is an active mountain belt formed by oblique collision between the Luzon arc and the Asian continent. Regardless of the ongoing collision in central and southern Taiwan, a post-collisional extension regime has developed since the Plio–Pleistocene in the northern part of this orogen, and led to generation of the Northern Taiwan Volcanic Zone. Emplaced at 0.2 Ma in the southwest of the Volcanic Zone, lavas from the Tsaolingshan volcano are highly magnesian (MgO≈15 wt.%) and potassic (K₂O≈5 wt.%; K₂O/Na₂O≈1.6–3.0). Whereas these basic rocks (SiO₂≈48 wt.%) have relatively low Al₂O₃≈12 wt.%, total Fe₂O₃≈7.5 wt.% and CaO≈7.2 wt.%, they are extremely enriched in large ion lithophile elements (LILE, e.g. Cs, Rb, Ba, Th and U). The Rb and Cs abundances, >1000 and 120 ppm, respectively, are among the highest known from terrestrial rocks. In addition, these rocks are enriched in light rare earth elements (LREE), depleted in high field strength elements (HFSE), and display a positive Pb spike in the primitive mantle-normalized variation diagram. Their REE distribution patterns mark with slight Eu negative anomalies (Eu/Eu*≈0.90–0.84), and Sr and Nd isotope ratios are uniform (⁸⁷Sr/⁸⁶Sr≈0.70540–0.70551; ¹⁴³Nd/¹⁴⁴Nd≈0.51268–0.51259). Olivine, the major phenocryst phase, shows high Fo contents (90.4±1.8; 1σ deviation), which are in agreement with the whole rock Mg-values (83–80). Spinel inclusions in olivine are characterized by high Cr/Cr+Al ratios (0.94–0.82) and have compositions similar to those from boninites that originate from highly refractory peridotites. Such petrochemical characteristics are comparable to the Group I ultrapotassic rocks defined by Foley et al. [Earth-Sci. Rev. 24 (1987) 81], such as orogenic lamproites from central Italy, Span and Tibet. We therefore suggest that the Tsaolingshan lavas resulted from a phlogopite-bearing harzburgitic source in the lithospheric mantle that underwent a recent metasomatism by the nearby Ryukyu subduction zone processes. The lavas exhibit unique incompatible trace element ratios, with Rb/Cs≈8, Ba/Rb≈1, Ce/Pb≈2, Th/U≈1 and Nb/U≈0.8, which are significantly lower than the continental crust values and those of most mantle-derived magmas. Nonmagmatic enrichment in the mantle source is therefore required. Based on published experimental data, two subduction-related metasomatic components, i.e., slab-released hydrous fluid and subducted sediment, are proposed, and the former is considered to be more pervasive for causing the extraordinary trace element ratios observed. Our observations lend support to the notion that dehydration from subducting slabs at convergent margins, as a continuing process through geologic time, can account for the fractionation of these elemental pairs between the Earth's crust and mantle.     

海南岛红树林泥炭中硫及其成因研究

海南岛红树林泥炭普遍富硫。黄铁矿、硫酸盐和有机硫是泥炭中硫的三种主要赋存形态,其中,以黄铁矿硫高为特征。利用形态硫分析、硫同位素分析等手段结合硫的时空变化特征,研究了泥炭中硫的形成机理。泥炭中硫的富集与泥炭坪环境具紧密的成因联系,全硫和形态硫的时空变化受微环境的控制;潮坪水介质中的硫酸盐是泥炭中硫的最初来源;泥炭中硫的加入,主要发生于准同生价段,在加入过程中还原硫细菌起了决定性作用。定量沉积环境分析是查明古代富硫煤田硫分布的主要途径。     

嵩县雷门沟金矿地质特征及次生富集作用

本文从三条典型含金蚀变破碎带入手 ,通过对其次生富集带的分析、对比、归纳 ,揭示出次生富集带的深度、厚度和品位变化规律 ,并进一步从理论上阐明次生富集带的形成机理。     

东濮凹陷盐湖盆地油气富集规律研究

国内外油气勘探实践表明,含盐盆地的油气富集和分布与盆地内沉积的盐岩密切相关。东濮凹陷是我国东部地区典型的含盐油气富集盆地,作者通过深入研究其地层层序特征及盐岩纵横向分布特点,进一步剖析了盐岩沉积的主要控制因素及其与生储盖层的关系,搞清了含盐盆地油气的分布和富集与盐岩的关系,指出无论在垂向上还是横向上,东濮凹陷盐岩一般都与暗色烃源岩共生,而且盐岩与同期沉积的砂岩表现为长消关系。研究认为盐岩可作为油气上盖或侧向遮挡,与源岩、储集层可组成良好的生储盖配置关系,利于油气富集区带的形成,对构造和隐蔽油气藏的形成都发挥了积极的作用,并指出与盐岩有关的文东北部和胡状集地区是下一步挖潜的有利勘探方向。研究成果也可为国内外同类含盐盆地的油气勘探提供一定的借鉴经验。