中天山天湖东铁钼矿含矿片麻状花岗岩年代学、地球化学和锆石Hf同位素-对于中天山早古生代构造演化的启示

以中天山东段的天湖东铁钼矿含矿花岗岩为例,在LA-ICP-MS锆石U-Pb年代学测定其为早古生代花岗岩（（445.3±4.6） Ma）基础上,通过岩相学、地球化学及锆石原位Hf同位素组成等多方面研究,探讨该岩体的成岩作用及其构造背景。天湖东含矿片麻状花岗岩的主要矿物为斜长石、石英、钾长石,并含少量黑云母和角闪石等。全岩地球化学分析结果表明,该片麻状花岗岩高硅、弱富铝、富钙、富钠而贫钾,ASI值为0.68~0.82,属于准铝质钙碱性花岗岩,总体上富集大离子亲石元素（LILE）Rb、Ba等和轻稀土元素La、Ce、Nd等,而亏损高场强元素Nb、Ta、Ti、Yb等,轻重稀土分异明显,轻稀土分异较为明显,而重稀土分异不明显,表现出典型岛弧岩浆岩的地球化学特征。锆石的ε_Hf(445 Ma)值为-6.31~-1.77,二阶段Hf模式年龄（T_DM2）为1.538~1.825 Ga,表明该花岗岩的源区主要为壳源物质。综合分析上述资料,认为天湖东铁钼矿片麻状花岗岩是由俯冲过程中地壳物质重熔的产物。结合前人的研究和本课题组的新近研究成果认为,在早古生代时,中天山为岩浆弧构造环境,形成一系列的钙碱性岩浆岩,而该岩浆弧的形成可能是受到介于吐哈陆块和塔里木板块之间的古天山大洋在早古生代时期向南俯冲而形成的。     

淮北矿区煤层气资源勘查潜力评价

淮北矿区地处华东腹地,煤层气资源丰富,具备大规模开发的前景。选用层次分析法与灰色聚类法评价方法,通过构建层次结构模型、计算指标权重、制定参数分类评价标准、运用灰色聚类法判别灰类、计算综合优度值,对矿区16个评价单元的山西组和下石盒子组煤层气资源潜力进行了评价,结果显示,淮北矿区山西组煤层气勘查潜力中等,下石盒子组勘查潜力较好。     

Seismic response for an isosceles triangle hill subjected to anti-plane shear waves

Acta Geotechnica - This paper presents an exact, analytical solution to the boundary value problem of the anti-plane (SH) waves scattering by an isosceles triangle hill on an elastic half-space by...     

Water–rock interaction during the process of steam stimulation exploitation of viscous crude oil in Liaohe Shuguang Oil Field, Liaoning, China

In the process of steam stimulation exploitation of viscous crude oil, the injected water, at high temperature and under high pressure, reacts intensively with the host rock. This kind of water–rock interaction in Liaohe Shuguang Oil Field was studied on the basis of analysis of water composition changes, laboratory experiments, mineral saturation indices analysis, and mass balance calculation. Compared with the injected water, the changes of the composition of discharged water are mainly the distinct decrease of pH, Na⁺, SiO₂ and Cl⁻, as well as the increase of K⁺, Ca²⁺, Mg²⁺, SO ₄ ²⁻ and HCO ₃ ⁻ . Laboratory experiments under field conditions showed: the dissolution sequence of minerals quantitatively is quartz>potassium feldspar>albite, and the main change of clay minerals is the conversion of kaolinite to analcime. Mass balance calculation indicated during the process of steam stimulation, large quantities of analcime are precipitated with the dissolution of large amounts of quartz, kaolinite, potassium feldspar, and CO₂. These results correlated very well with the experimental results. The calculated results of Liaohe Shuguang Oil Field showed that during the steam stimulation for viscous crude oil, the amounts of minerals dissolved (precipitated) are huge. To control the clogging of pore spaces of oil reservoirs, increased study of water–rock interaction is needed.     

深层地震资料采集的若干问题

本文着重叙述检波器组合效应、最大炮检距的选择、深反射层的共反射点离散效应等项技术和问题。另外讨论了比较理想的深层资料采集方法。     

张河湾水库地区断层的ESR年龄测定

本文叙述了电子自旋共振(简称ESR)法所测定的河北省张河湾水库F₁、F₇断层的年龄,将ESR年龄和以往测试的TL年龄进行对比,两种方法测试结果基本吻合,证明ESR测定第四纪断层的可能性,F₁、F₇断层的年龄值均大于定义的活动断层年龄值下限(1.1×104a)。因此,它们不属活动断层,这个结论也被其它地质观测手段所证实。      

Distribution Characteristics of Gold and Other Trace Elements in the Proterozoic Lengjiaxi Group,Northeastern Hunan Province

Systematic geochemical studies of the Proterozoic Lengjiaxi Group in northeastern Hunan Province suggest that the Lengjiaxi Group is a Au-As-Sb-W association-type Au-bearing turbidite formation.The contents of Au,As,Sb,W,Cr,Mn,Pb and Zn in the turbidite formation are more than two times as high as the average contents of trace elements in the upper continental crust.The low abundance of Ag and the close correlation between Au and As are two important characteristic features.In the Au-bearing turbidite formation the enrichment of gold is due to the extensive occurrence of Au-bearing pyrites.Higher contents of Au,W,Sb and Ag in the greywacke indicate that they also exist in the form of heavy minerals.Au,Ag,As,Sb,W and REE in the Au-bearing turbidite formation have a close genetic relation with the chemistry of the gold deposits.     

A Study on Crack Damage Stress Thresholds of Different Rock Types Based on Uniaxial Compression Tests

When rock samples are loaded until macroscopic fractures develop, the failure process can be divided into several stages based on axial and lateral strain responses or the acoustic emission sequence during uniaxial compression tests. Several stress thresholds may be identified: the crack closure stress σ _cc, crack initiation stress σ _ci, crack damage stress σ _cd, and uniaxial compressive strength σ _ucs; these may be used as a warning indicator for rock rupture. We investigated the crack damage stress σ _cd, its threshold, and a possible relationship between σ _cd and the uniaxial compressive strength. The σ _cd of different rock types were compiled from previous studies based on uniaxial compression tests. The results showed that the overall averages and standard deviations of σ _cd /σ _ucs for igneous, metamorphic, and sedimentary rocks were ~0.78 (±0.11), ~0.85 (±0.11), and ~0.73 (±0.18), respectively. There were no significant differences in σ _cd /σ _ucs between the different rock types, except that the sedimentary rock had a slightly larger standard deviation attributed to the variation of porosity in the samples, while the metamorphic rock had higher average σ _cd /σ _ucs resulting from the small statistical sample size. By excluding the higher-porosity (>10 %) rock samples, the averages and standard deviations of σ _cd /σ _ucs for igneous, metamorphic, and sedimentary rocks were ~0.78 (±0.09), ~0.85 (±0.09), and ~0.78 (±0.11), respectively. The results imply that the rock origin process (i.e., igneous, metamorphic, and sedimentary) has a minimal effect on σ _cd /σ _ucs. The ratio σ _cd/σ _ucs could be an essential intrinsic property for low-porosity rocks, which could be used in rock engineering for predicting the failure process.     

Proterozoic copper deposits in NW Queensland,Australia: Sulfur isotopic data

Sulfur isotopic disequilibrium is commonly observed between associated pyrite and copper sulfides in NW Queensland. A sulfur isotopic study of copper mineralization in dolomites at Paradise Valley and arenites at Mammoth has allowed the significance of such disequilibrium to be evaluated. Copper mineralization at Paradise Valley is characterized by a greater enrichment in ³⁴S, with δ³⁴S values often greater than +30‰, for both copper sulfides and associated syngenetic/diagneetic pyrite. At Mammoth, copper sulfides have isotopic compositions (δ³⁴S=?15.9 to ?0.3‰) transitional between disseminated syngenetic/diagenetic pyrite (δ³⁴S=?5.7 to ?1.7‰) and epigenetic vein pyrite (δ³⁴S=?17.9 to ?7.1‰) suggesting progressive reaction and replacement of syngenetic/diagenetic pyrite by a copper-bearing mineralizing fluid under oxidizing conditions. The isotopic data, within the constraints imposed by geological and geochemical factors, support a model of reaction between copper-bearing mineralizing fluids and pre-existing syngenetic/diagenetic pyrite for both the carbonate- and arenite-hosted deposits.     

Science and Technology of Delimitation of Continental Shelf and Its Application in Maritime Silk Road Cooperation*

Delimitation of the continental shelf is an emerging interdisciplinary discipline in the field of international marine science and technology. It uses the scientific and technological means to expand the jurisdiction of coastal states based on the international rules of the 《United Nations Convention on the Law of the Sea》. Therefore, it is related to the marine sovereignty rights and interests of a country and also a hot topic of science and technology that all countries have competed to develop. China has launched the research in this field simultaneously with the world's maritime powers, and formed its innovative advantages in such aspects as geological models, detection techniques and delimitation systems in the delimitation of continental shelf, which have become the brand new ties for China's cooperation with foreign countries in marine science and technology, and also the important field in the maritime silk road cooperation in the 21^st century. This paper introduced the basic principles and methods in the delimitation of continental shelf beyond 200 nautical miles (370 km), progress in the delimitation of the global continental shelf, and China's innovative science and technology as well as its application in maritime Silk Road cooperation, and provided the prospect of the future scientific and technological cooperation with foreign countries and development in this filed. And it was suggested China should develop the scientific and technological cooperation on the delimitation of the continental shelf along the Silk Road, promote the scientific and technological development of the delimitation of the continental shelf in China, and enhance China's influence and voice in international ocean affairs.