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101.
The Baimazhai nickel deposit, Yunnan Province, China, is located in the southern part of the Sanjiang (Tri-river) alkali-rich intrusive rock belt (Sanjiang ARIR). In this paper was conducted ^40Ar-^39Ar dating of two phlogopites in lamprophyres which are, as dikes, widely distributed in the orefield, and two plateau ages were acquired, i.e., 32.46±0.62 Ma and 32.01±0.60 Ma, respectively (averaging 32.23±0.60 Ma). The ages are obviously younger than those of the ore-hosted complex and mineralization of the Baimazhai nickel deposit. In combination with the characteristics, it is indicated that lamprophyres in the orefield and those in the Sanjiang ARIR are similar in tectonic setting, mineral assemblage and geochemistry. It is considered that lamprophyres in the orefield are the important component of the Sanjiang ARIR, and the lamprophyres and ore-hosted complex in the orefield represent the products of two times of different magmatic activity from different mantle sources. On the other hand, the age of lamprophyres in the orefield is older than that of the strike-slip shearing of the Ailaoshan-Honghe fault belt, suggesting that the strike-slip shearing of the Ailaoshan-Honghe fault belt is not the factor leading to magmatic activity of lamprophyres in the orefield, while it is more possible that magmatic activity of the Sanjiang ARIR promoted strike-slip shearing of the fault belt. 相似文献
102.
Extensive organic-matter (OM) rich facies (black shales) occur in the Ordo-Silurian boundary successions in the Yangtze area, South China. To investigate the redox changes of the Yangtze Sea during the Ordo-Silurian transition, two OM sections (Wangjiawan in Yichang, Hubei Province, and Sanjiaguan in Zhangjiajie, Hunan Province) straddling the Ordo-Silurian boundary are studied. The measurements finished in this study include contents of the total organic carbon (TOC), pyrite sulphur, and different species of Fe, including dithionite-extractable Fe (FED), pyrite Fe (FeP), HCl-extractable Fe (FeH), and total Fe (FeT), in black shales, as well as other redox proxies, such as the SIC ratio, the ratio between highly reactive Fe (FeHR = FeD + FeP) and FeT, and the FeP/(FeP + FeH) ratio, known as the degree of pyritization (DOP). In the Wangjiawan section, the Middle Ashgill sediments have high FeHR/FeT ratios (0.20-0.77; avg. 0.45), high DOP values (0.21-0.72; avg. 0.54), and a relatively constant sulfur content independent of the organic carbon content. By the contrast, the mid-early Hirnantian deposits generally have low FeHR/FeT ratios (0.10-0.35; avg. 0.21), low DOP values (0.11- 0.40; avg. 0.28), and SIC values are clustering on the normal marine value (SIC = 0.36). The late Hirnantian and early Rhuddanian deposits, similar to those of the Middle Ashgill deposits, are characterized by high FeHR/FeT ratios (0.32-0.49; avg. 0.41), high DOP values (0.46-0.68; avg. 0.53) and fairly constant sulfur contents. These data suggest the occurrences of marine anoxia on the Yangtze Sea shelf during intervals of the Mid Ashgill, Late Hirnantian and Early Rhuddanian, and ventilated and oxygenated marine conditions during the mid-early Hirnantian time. The mid-early Hirnantian ventilated event was concomitant with the global glacial period, likely resulted from the glacio-eustatic sea-level fall and subsequent circulation of cold, dense oxygenated waters 相似文献
103.
对专项农用土地整理-"金土地工程"区大比例尺农业地质调查中的土壤地球化学测量方法及精度进行了试验.结果表明,单样分析能更真实地反映土壤地球化学的分布特征,经济实用的采样密度为16点/ km2~32点/ km2(100ha),地球化学图件编绘以距离倒数插值法成图效果更好. 相似文献
104.
基于RBF(Radial Basis Function)网络的正交最小平方算法,对攀枝花地质样品进行动态非线性基体效应校正.首先采用EDXRF仪器对样品进行测量,并对样品的荧光计数进行归一化,设计出自动分类模型和动态非线性数据基体效应校正模型的二级串联结构,用自组织神经网络(SOFM)进行分类,然后用RBF网络预测了未知样品元素Ti的百分含量.结果表明:对所预测样本的Ti的百分含量与化学分析相比的误差均小于0.5%.由此可见,用RBF方法可以有效地对地质样品进行非线性基体效应校正,能够达到工矿生产的要求. 相似文献
105.
106.
根据天津含水介质的结构和组成,选择代表性的2种含水介质,分析了土样和胶体的主要物理和化学性质,系统测定不同胶体对氨氮吸附的动力学曲线和吸附等温线,并分析了胶体粒径、ζ电位、电泳淌度对吸附作用的影响。结果表明,含水介质胶体对氨氮的吸附动力学过程为对数曲线,其平衡时间约为20~24 h;不同胶体的吸附等温线均为直线型理想吸附,并且当水相中氨氮浓度低于一定浓度时,不但不产生吸附,反而使胶体中的残留氨氮释放出来;胶体颗粒细,比表面积大,表面能大,吸附能力就越大;胶体的ζ电位和淌度愈高,胶体的稳定性愈大,与铵离子接触的机会多,容易吸附铵离子。 相似文献
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