喇嘛苏铜矿中酸性岩体岩石学特征

采用费氏台五轴定位法和D C Noble等提出的求斜长石成分和有序度方法、鉴定图表,在喇嘛苏矿区三种中酸性岩体的岩石薄片中选择比较新鲜的、自形程度较好的斜长石,测得斜长石牌号χ(An)=24～56,有序度S=0.4～0.7,说明斜长石以中长石为主,属中温型,即在结晶过程中岩浆冷却的速度较快;斜长石环带有正常环带,也有韵律环带,表明在结晶过程中总体是正常结晶环境,而期间有上下反复运动和岩浆房内压力的反复变化。     

新疆西天山古生代侵入岩的地质特征及构造意义

新疆西天山造山带位于古亚洲构造域的中南部,古生代岩浆活动强烈,侵入岩发育。文章系统总结了新疆西天山古生代侵入岩的时空分布、地质特征及其地球化学特征,认为其是南、北天山洋盆演化的产物,早石炭世及其以前的古生代侵入岩呈带状分布于各山系中,主要为一套与洋盆收敛俯冲有关的钙碱性侵入岩,晚石炭世及其之后的古生代侵入岩则具有面状分布的特征,主要为一套与同碰撞有关的富铝花岗岩和后造山的富钾花岗岩。     

辽东半岛印支期侵入岩侵入机制与岩浆大陆动力学演化

辽东半岛广泛分布印支期侵入岩,作为研究辽东半岛印支期陆内造山作用的客观实体,意义重大.概述了印支期侵入岩地质特征、岩石化学及地球化学特征,总结出岩浆演化趋势由超基性→基性→中性→酸性→碱性.提出了岩浆源区性质为幔源、壳幔混源、壳源3种类型.总结了造山初期至造山早期伸展机制下席状侵位,造山主期穹隆式及穿刺式侵位,造山后构造崩塌被动侵位3种侵位机制模式及岩浆大陆动力学演化过程.     

新疆东昆仑白干湖钨锡矿床地质特征

白干湖钨锡矿床赋存在古元古界金水口群变质岩系中,矿体受北东向白干湖断裂带控制,加里东期酸性侵入岩与矿床关系密切.区内是钨元素地球化学高背景区,在各类地质体钨元素富集系数为9.57~25.30.目前共发现17条矿体,矿石类型为夕卡岩型白钨矿和石英脉型黑钨矿.矿床类型为沉积变质岩浆再造型钨锡矿床.     

Digital mapping of riverine waterway hydrodynamic and geomorphic features

This paper proposes an innovative, non‐intrusive method for mapping waterway characteristics in riverine areas. The technique uses photogrammetry to provide quantitative information about the dry area in the vicinity of the waterways (banks and floodplain) and image processing algorithms to characterize the flow. Riverside images of a riverine area are decomposed into quasi‐planar areas and ortho‐rectified and re‐assembled to obtain a panoramic ortho‐view of the area of interest. Morphological features of interest (such as river bank positions, flood plain edges, mud deposits, vegetation and erosion patterns) are then identified on the ortho‐view and mapped digitally. Image sequences of the river flow are recorded, allowing a surface velocity analysis to be obtained through Large Scale Particle Image Velocimetry (LSPIV). Finally, the mapped elements and the surface velocities are displayed together in a GIS‐like visualization. Through the presentation of a case study of a flood event at a culvert site, this paper demonstrates the capability of the technique to monitor characteristics of waterways over time. The method is inexpen‐sive (a conventional video or digital camera can be used), fast and requires minimum preparation. It can be applied in such important river‐related research areas as morphodynamic and sediment transport studies. It also fosters an improved understand‐ing of the coupling between the river and its banks, which is essential for river restoration and eco‐habitat studies. The present methodology is readily available for implementation in routine bridge inspections, fitted with an easy‐to‐use graphical interface. Copyright © 2009 John Wiley & Sons, Ltd.     

大兴安岭中南段杜尔基地区早白垩世侵入岩岩石地球化学特征及构造环境

杜尔基地区处于大兴安岭中南段,区内中生代侵入岩广泛发育。八个样品K—Ar全岩法测年结果为100．15～120．29Ma,形成于早白垩世。岩石化学分析结果具有高硅、高钾、富碱、过铝、贫铁、镁、钙特征,属于碱性岩系列。稀土元素总量平均值为146．85μg/g,球粒陨石标准化曲线整体平缓右倾,显示富Rb,贫Sr、Ba特征,具有Eu负异常,微量元素具有明显的Sr、Ba、Ti负异常,反映了具有强烈分异的分离结晶作用存在,说明岩石形成于长期较稳定的构造背景,可能形成于非造山板内裂谷或热点地幔柱环境。     

Effects of abnormally high heat stress on petroleum in reservoir

An igneous intrusion of 94m thick was discovered intruding into the Silurian sandstone from Tazhong 18 Well. The petroleum previously preserved in the Silurian sandstone reservoir was altered into black carbonaceous bitumen by abnormally high heat stress induced by the igneous intrusion. The reflectance of the carbonaceous bitumen reaches as high as 3.54%, indicating that the bitumen had evolved into a high thermal evolution level. Similar to the Silurian samples from the neighboring Tazhong 11, Tazhong 12, Tazhong 45 and Tazhong 47 wells, the distribution of C₂₇, C₂₈ and C₂₉ steranes of the carbonaceous bitumen is still “V”-shaped and can still be employed as an efficient parameter in oil source correlation. The “V”-shaped distribution indicates that the hydrocarbons from the Tazhong 18 and the neighboring wells were all generated from the Middle-Upper Ordovician hydrocarbon source rocks. However, the oil source correlation parameters associated with and terpanes had been changed greatly by the high heat stress and can no longer be used in oil source correlation. The δ ¹³C values of the petroleum from the neighboring wells are between −32.53%. and −33.37%., coincident with those of the Paleozoic marine petroleum in the Tarim Basin. However, the δ ¹³C values of the carbonaceous bitumen from the Tazhong 18 Well are between −27.18%. and −29.26%., isotopically much heavier than the petroleum from the neighboring wells. The content of light hydrocarbons (nC₁₄−nC₂₀) of the saturated hydrocarbon fraction in the carbonaceous bitumen is extremely higher than the content of heavy hydrocarbons. The light/heavy hydrocarbon ratios (ΣnC₂₁ ⁻/ΣnC₂₂ ⁺ are between 4.56 and 39.17. In the saturated fraction, the even numbered hydrocarbons are predominant to the odd numbered, and the OEP (Odd to Even Predominance) values are between 0.22 and 0.49. However, the content of light hydrocarbons in the petroleum from the neighboring wells is relatively low and the content of the even numbered hydrocarbons is almost equal to that of the odd numbered. Compared with the samples from the neighboring wells, the abundance of non-alkylated aromatic hydrocarbons, such as phenanthrenes, and polycyclic aromatic hydrocarbons (PAHs), such as fluoranthane, pyrene, benzo[a]anthracene and benzofluoranthene, are relatively high. Supported by the National Key Basic Research and Development Project (Grant No. 2005CB422103)     

Zircon U-Pb and geochemical analyses for leucocratic intrusive rocks in pillow lavas in the Danfeng Group,north Qinling Mountains,China

Field observation showed that there are many irregular leucocratic intrusive rocks in pillow lavas in the Danfeng Group in the Xiaowangjian area, north Qinling orogenic belt. Photomicrographs indicated that the protoliths of those altered leucocratic intrusive rocks are dioritic rocks. Geochemical analyses showed that pillow lavas have a range of SiO2 from 47.35% to 51.20%, low abundance of TiO2 from 0.97% to 1.72%, and percentages of MgO (MgO#=41―49). Chondrite-normalized REE patterns of pillow lavas are even, indicative of a weak differentiation between LREE and HREE (La/YbN=1.52―0.99). N-MORB-normalized trace element abundances showed that pillow lavas are enriched in incompatible elements (e.g., K, Rb, and Ba). Leucocratic intrusive rocks in pillow lavas have a wide range of SiO2 from 53.85%―67.20%, low abundances of TiO2 from 0.51%―1.10%, and MgO (MgO#=40―51), and higher percentages of Al2O3 (13.32%―16.62%) and concentration of Sr (342-539 μg/g), ratios of Na2O/K2O (2―7) and Sr/Y (17―28). Chondrite-normalized REE patterns of leucocratic intrusive rocks showed highly differentiation between LREE and HREE (La/YbN=12.26―19.41). N-MORB-normalized trace element abundances showed that leucocratic intrusive rocks are enriched in incompatible elements (e.g., K, Rb, and Ba), and significantly depleted in HFSE (e.g., Nb, Ta, Zr and Ti), indicative of a relationship to subduction. Isotopically, leucocratic intrusive rocks have a similar εNd(t) ( 7.45― 13.14) to that of MORB ( 8.8― 9.7), which indicates that those leucocratic intrusive rocks sourced from depleted mantle most likely. SHRIMP U-Pb analyses for zircon showed that those leucocratic intrusive rocks were formed at 442±7 Ma, yielding an age of subduction in the early Paleozoic in the north Qinling orogenic belt.     

内蒙古孟恩陶勒盖岩体的成岩时代——LA-ICP-MS锆石U-Pb同位素年代学

孟恩陶勒盖岩体侵位于兴蒙造山带晚古生代浅变质岩系内,根据岩石类型划分为中细粒英云闪长岩、花岗闪长岩和二长花岗岩3个填图单位,具有典型S型花岗岩的矿物组成和岩石化学特征.花岗闪长岩和二长花岗岩LA-ICP-MS锆石U-Pb同位素年龄测定结果分别为234±1 Ma和230±1 Ma,时代为中三叠世,代表孟恩陶勒盖岩体的侵位时代.     

辽宁凌源柏杖子金矿床地质特征及成矿模式

柏杖子金矿系辽西凌源地区重要的岩浆热液型金矿.矿区出露的地层主要为中元古代长城系大红峪组,其次为太古宙建平群变质岩系.长城系大红峪组为金矿的主要容矿围岩,太古宙建平群变质岩系为金矿的矿源层.柏杖子岩体为区域上大柱子岩体的分支岩体,柏杖子岩体由地壳深部上侵的过程中萃取了建平群变质岩系中的成矿物质,沿北北东-北东方向上侵并在长城系大红峪组地层中形成金矿体.通过总结、分析成矿的主要过程,建立了柏杖子金矿的成矿模式.