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941.
Characteristics and uranium mineralization of ore-bearing rock series in Qianjiadian sandstone-type uranium deposits,Songliao Basin 下载免费PDF全文
Song Bai-Rong Sun Hui Yang Song-Lin Han Hong-Dou Li Qing-Chun Shi Yu-Hua Tang Jie-Yun Liu Yu-Ting 《古地理学报》1999,22(2):309-320
The Qianjiadian sandstone-type uranium deposit in Songliao Basin has become an ultra-large uranium deposit since its exploration and continuous development. The geological and metallogenic characteristics of this area have been studied widely since its discovery,but the detailed petrological features of its ore-bearing construction and favorable metallogenic conditions still require much detailed research. The mineralization of urnium deposit includes various geological processes resulting in the accumulation of uranium element. The source rock with high uranium concentration and much easier for the leaching of uranium is the basis of uranium mineralization. The later oxidation-reduction,mineral alteration are the key for the uranium deposits. In this paper,the petrological characteristic of lithology sandstone-type uranium deposit is studied by using the micro experimental analysis. It is found that the host rocks are primarily composed of medium-fine grained feldspar lithic sandstone,fine grained feldspar lithic sandstone,boulder-clay-bearing sandstone and glutenin. The amount of quartz and feldspar are close to the rock debris. The debris are mainly composed of rhyolite,rhyolitic tuff,and some trochyte,ayenite-aplite,granite,granite porphyry,andesite,silicalite and mudstone etc. the epigenetic alteration includes the carbonatization and kaolinization is general and intense at the local region,followed by the secondary epigenetic alteration includes pyritization,ferrugination and little baratization. Deep oil and gas infiltrate into the oil-bearing strata causing the oil stains,spots and spillage. The symbiosis of pyrite berry globule and micritic pyrite are common. The uranium element exists in the uranium-bearing minerals(e.g.,asphalt and coffinite)as well as the adsorbed state. The multi-genesis and multi-stages of the metallogenic model is established,i.e.,sedimentary preconcentration stage-interlayer infiltration stage-the oil and gas transformation stage-the oil and gas reduction stage. 相似文献
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944.
勉略宁地区区域地质背景,矿床类型及其成矿特点 总被引:9,自引:3,他引:6
以地质演化为基础,从沉积-构造-岩浆-变质-成矿作用角度进行综合对比分析,提出煎茶岭—七里店和黑木林—峡口驿两大构造岩浆带对勉略宁地区矿床起主控作用, 认为各类型矿床成矿作用与先存基底岩石有成生关系, 将矿床形成时代统一在秦岭陆-陆碰撞时限范围, 对该地区地质找矿工作及矿床理论研究进行了讨论。 相似文献
945.
华北地台前寒武花岗岩类、陆壳演化与克拉通形成 总被引:30,自引:12,他引:18
通过华北前寒武纪花岗岩类的研究,提出英云闪长岩和奥长花岗岩(T1T2)代表不成熟陆壳组成,T1T2G1G2代表半成熟陆壳组成,花岗闪长岩和花岗岩(G1G2)代表成熟陆壳组成。讨论了大陆根的形成与性质。识别出华北地台内10个太古陆核。讨论了中太古代初始陆核、新太古代陆核;新太古代末两个微大陆尺度的陆核的形成;早元古代两个成熟陆核的构造拼合并形成华北克拉通 相似文献
946.
江西南部鸡笼嶂组研究的新进展 总被引:8,自引:3,他引:5
分析了江西南部鸡笼嶂组划分的现状及存在的问题,提出了龙南盆地和石马剖面的“鸡笼嶂组”属中侏罗世-晚侏罗世早期余田群上部菖蒲组的一部分;菖蒲盆地的“鸡笼嶂组”属早白垩世晚期-晚白垩世早期版石群优胜组。鉴于安远、河岭、蔡坊、岩背等盆地的鸡笼嶂组属晚侏罗世,为火山喷发期的产物,而且整合于鸡笼嶂组之下的上丁组为火山初始期的产物,建议将赣南地区晚侏罗世火山活动形成的上丁组和鸡笼嶂组统称为莲花寨群。指出安远莲 相似文献
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948.
本文针对中国石油集团测井有限公司(CPL)三维阵列感应测井仪器(Three Dimensional Induction Tool,TDIT)的真实结构与参数,利用2.5维数值模式匹配技术研究建立水平层状非均质TI地层中仪器偏心情况下三维感应测井响应的高效数值模拟算法.首先,利用2.5维数值模式匹配技术给出水平层状非均质TI模型中偏心磁流源并矢Green函数的半解析解.在此基础上,结合三维阵列感应测井仪器参数以及测量过程中出现的仪器偏心与旋转等实际情况,通过叠加原理推导出该仪器响应的有效计算公式.最后,通过数值模拟结果分析考察仪器偏心、仪器自旋角等参数对测井响应的影响以及变化特征,为多分量感应资料处理与解释提供理论基础. 相似文献
949.
Strong variation in weathering of layered rock maintains hillslope‐scale strength under high precipitation 下载免费PDF全文
Jennifer Von Voigtlander Marin K. Clark Dimitrios Zekkos William W. Greenwood Suzanne P. Anderson Robert S. Anderson Jonathan W. Godt 《地球表面变化过程与地形》2018,43(6):1183-1194
The evolution of volcanic landscapes and their landslide potential are both dependent upon the weathering of layered volcanic rock sequences. We characterize critical zone structure using shallow seismic Vp and Vs profiles and vertical exposures of rock across a basaltic climosequence on Kohala peninsula, Hawai’i, and exploit the dramatic gradient in mean annual precipitation (MAP) across the peninsula as a proxy for weathering intensity. Seismic velocity increases rapidly with depth and the velocity–depth gradient is uniform across three sites with 500–600 mm/yr MAP, where the transition to unaltered bedrock occurs at a depth of 4 to 10 m. In contrast, velocity increases with depth less rapidly at wetter sites, but this gradient remains constant across increasing MAP from 1000 to 3000 mm/yr and the transition to unaltered bedrock is near the maximum depth of investigation (15–25 m). In detail, the profiles of seismic velocity and of weathering at wet sites are nowhere monotonic functions of depth. The uniform average velocity gradient and the greater depths of low velocities may be explained by the averaging of velocities over intercalated highly weathered sites with less weathered layers at sites where MAP > 1000 mm/yr. Hence, the main effect of climate is not the progressive deepening of a near‐surface altered layer, but rather the rapid weathering of high permeability zones within rock subjected to precipitation greater than ~1000 mm/yr. Although weathering suggests mechanical weakening, the nearly horizontal orientation of alternating weathered and unweathered horizons with respect to topography also plays a role in the slope stability of these heterogeneous rock masses. We speculate that where steep, rapidly evolving hillslopes exist, the sub‐horizontal orientation of weak/strong horizons allows such sites to remain nearly as strong as their less weathered counterparts at drier sites, as is exemplified by the 50°–60° slopes maintained in the amphitheater canyons on the northwest flank of the island. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
950.
SHRIMP U–Pb ages of detrital zircons from the Early Cretaceous Nakdong Formation,South East Korea: Timing of initiation of the Gyeongsang Basin and its provenance 下载免费PDF全文
To constrain the depositional age of the lowermost Nakdong Formation in the Early Cretaceous Gyeongsang Basin, SHRIMP U–Pb age determination was carried out on zircon separates. The U–Pb compositions of detrital zircons from the Nakdong Formation yield a wide range of ages from the Archean to the Cretaceous but show a marked contrast in age distribution according to the geographical locations within the basin. The provenance of the southern Nakdong Formation is dominantly the surrounding Yeongnam Massif, which is composed of Paleoproterozoic metamorphic rocks and Triassic to Jurassic plutonic rocks, whereas the central to northern Nakdong Formation records significant sediment derivation from the Okcheon Metamorphic Belt, which is distributed to the northwest, in addition to the contribution from the Yeongnam Massif. It is suggested that the maximum depositional age of the Nakdong Formation is ca 127 Ma, based on its youngest detrital zircon age population. The onset of its deposition at 127 Ma coincided with the tectonic inversion in East Asia from a compressional to an extensional geodynamic setting, probably due to the contemporaneous change in the drift direction of the Izanagi Plate and its subsequent oblique subduction. 相似文献