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大东山岩体位于多组深大断裂交汇处,区域构造应力环境由挤压造山变为陆壳伸展,伴随强烈的构造-岩浆活动和铀成矿作用。区内发育NE、近SN向两组构造,其中NE向为区内控制矿化的主要构造,控制了燕山期各阶段花岗质岩浆的侵入形态、定位以及铀矿点、铀矿化点及铀异常点的空间展布。在矿化部位的中基性岩脉中发育硅化、赤铁矿化、褐铁矿化及绢云母化,可见黄铁矿,方铅矿,钙铀云母等。综合分析认为研究区具有良好的硅化带型铀成矿地质条件,铀资源找矿潜力良好,铀矿化严格受北东向硅化断裂带控制。 相似文献
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利用激光剥蚀电感耦合等离子质谱(LA-ICP-MS)对三峡地区二叠系茅口组牙形石的U-Th-Pb同位素年龄进行测定。结果表明该地层中牙形石的208Pb/232Th放射年龄为269±44,Ma,207Pb/235U放射年龄为256±39,Ma,接近二叠系茅口组的生物地层年龄。206Pb/238U的年龄为196±6,Ma,虽然准确度较高,但与前人推测的地层年龄相比偏低。此外,作者对牙形石的稀土元素(REE)组成进行了分析,并且发现牙形石的REE组成和Ce异常与古海水氧化还原条件有一定的相关性,可以指示古海水的信息。 相似文献
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利用激光剥蚀电感耦合等离子质谱 (LA-ICP-MS)对三峡地区二叠系茅口组牙形石的U-Th-Pb同位
素年龄进行测定。结果表明该地层中牙形石的 208Pb/ 232Th年龄为 269 ±44Ma ,207Pb/235U为 256 ±
39Ma叠系茅口组的生物地层年龄。206b/238U年龄为196 ±Ma,虽然准确度较高,但与前人推测的
地层年龄相比偏低。此外,作者对牙形石的稀土元素(REE)组成进行了分析,并且发现牙形石的 REE组成和Ce
异常与古海水氧化还原条件有一定的相关性,可以指示古海水的信息。 相似文献
素年龄进行测定。结果表明该地层中牙形石的 208Pb/ 232Th年龄为 269 ±44Ma ,207Pb/235U为 256 ±
39Ma叠系茅口组的生物地层年龄。206b/238U年龄为196 ±Ma,虽然准确度较高,但与前人推测的
地层年龄相比偏低。此外,作者对牙形石的稀土元素(REE)组成进行了分析,并且发现牙形石的 REE组成和Ce
异常与古海水氧化还原条件有一定的相关性,可以指示古海水的信息。 相似文献
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The redox sensitive elements, molybdenum (Mo) and uranium (U), in marine sediments from the latest Permian Dalong (大隆) Formation at the Shangsi (上寺) Section, Northeast Siehuan (四川), South China, were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) to determine their response to a range of redox conditions, and to estimate the organic carbon burial rate. On the basis of the correlation between authigenic Mo abundance and organic carbon content in modern oceans, the organic carbon burial rates were calculated for the rocks at Dalong Formation, ranging from 0.48-125.83 mmol/(m2-d), which shows a larger range than the mineralization rate of organic carbon at the continental margins (1.6-4.23 mmol/(m2.d)). The Zr-normalized Mo and U abundances show large fluctuations in the entire section. The maxima of Zr-normalized Mo abundance and thus the maxima of the organic carbon burial rates were observed at the interval between the 155th and 156th beds (404-407 m above the base of Middle Permian). A decrease (the minimum) in U/Mo ratios is present in this interval. It is speculated that the oxygen-limited conditions and ultimately anoxia or euxinia may develop within this depth interval. In contrast, an enhanced enrichment of Zr-normallzed U abundance is found, in association with less enrichment in Zr-normnllzed Mo abundance in the interval from the I51st to 154th beds (395-404 m above the base of Middle Permian), inferring the dominance of a suboxic/anoxic depositional condition (denitrifying condition), or without free H2S. The presence of small quantities of dissolved oxygen may have caused the solubilization and loss of Mo from sediments. It is proposed that the multiple cycles of abrupt oxidation and reduction due to the upwelllng at this interval lead to the enhanced accumulation of authigenic U, but less enrichment of Mo. A decrease in the contents of U, Mo, and TOC is found above the 157th bed (407 m above the base of Middle Permian), in association with the enhanced U/Mo ratio, suggesting the overall oxic conditions at the end of the Dalong Formation. 相似文献
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竹筒尖矿床位于粤北下庄矿田西北部,区内碱交代作用较发育,碱交代花岗岩主要呈面状展布,与铀矿化关系密切。为研究区内碱交代过程元素变化特征及其与铀成矿的关系,文章系统采集了5件碱交代花岗岩样品,分析了其主量及微量元素组成。结果表明,与新鲜花岗岩相比,碱交代花岗岩中SiO_2、Na_2O含量明显降低,而K_2O含量显著偏高,表明区内碱交代以钾质交代为主;碱交代花岗岩中相对富集Rb、Th及U元素,亏损Ba、Sr、Ti等元素,w(LREE)/w(HREE)值相对降低,δEu值与新鲜花岗岩一致。上述特征表明,区内碱交代花岗岩与新鲜花岗岩可能具有相同的形成环境及物质来源,同时暗示流体中的U可能来自花岗岩;碱交代作用的发育有利于富铀花岗岩中铀的活化转移,为成矿流体中铀的富集创造了有利条件。 相似文献
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