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41.
42.
库鲁克塔格赛马山地区前震旦纪地层,经历了多期变质变形作用改造.通过建立岩石序列和构造变形序列,解析变质变形作用,结合同位素地质年代学研究,厘定出该套地层在阜平、五台、吕梁、四堡、晋宁5个构造期发生的沉积作用、火山作用、变质作用、岩浆侵入活动及产生的构造形迹组合,在此基础上构建区域地质事件表. 相似文献
43.
Five volcanic rock samples and two granite samples taken from the volcanic basins in western Fujian and southern Jiangxi were dated by using the zircon laser albation-inductively coupled plasma mass spectrometry U-Pb method. Together with previously dated ages, the dates obtained provide important constraints on the timing of late Mesozoic tectonic events in SE China. The volcanic rock samples yield ages of 183.1±3.5 Ma, ca. 141 Ma to 135.8±1.1 Ma, 100.4±1.5 to 97.6±1.1 Ma, confirming three episodes of late Mesozoic volcanic activities, which peaked at 180±5 Ma, 140±5 Ma and 100±5 Ma, respectively, along the Wuyishan belt. Moreover, based on field investigations of these volcano-sedimentary basins, we have recognized two compressional tectonic events along this belt. The early one was characterized by Upper Triassic to Middle Jurassic NNE-trending folds that were intruded by late Jurassic granites; and the late one caused the Lower Cretaceous volcano-sedimentary layer to be tilted. The dated age 152.9±1.4 Ma of the granitic samples from the Hetian granitic pluton in the Changting Basin and that from the Baishiding granitic pluton, 100.2±1.8 Ma, in the Jianning Basin, give the upper boundaries of these two tectonic events respectively. Hence, the late Mesozoic tectonic evolution of SE China was alternated between extension and compression. 相似文献
44.
Detrital Zircon Dating of Meso- and Neoproterozoic Rocks in North China and Its Implications 总被引:4,自引:0,他引:4
Gao Linzhi Liu Pengju Yin Chongyu Zhang Chuanheng Ding Xiaozhong LIU Yanxue Song Biao 《《地质学报》英文版》2011,85(2):271-282
New dates from Meso- and Neoproterozoic strata contribute to the recently defined Precambrian stratigraphical timescale of China agreed by the Subcommission on the Precambrian System, and the National Commission on Stratigraphy of China on Nov. 24, 2009. First, the age range of the Changcheng System, including the Changzhougou, Chuanlinggou, Tuanshanzi and Dahongyu formations has been constrained to 1.8–1.6 Ga. Second, the Jixian System including the Gaoyuzhuang, Yangzhuang, Wumishan, Hongshuizhuang and Tieling formations has been constrained to 1.6–1.4 Ga. Third, an as-yet unnamed (undefined) system (1.4–1.0 Ga) is only developed in the Xiamaling Formation at the Jixian section, Tianjing. Fourth, the Qingbaikou System, including the Luotuoling and Jing’eryu formations has been constrained to 1.0–0.78 Ga. Fifth, the Nanhuan System ranges between 780–635 Ma, and the Sinian System is within 635–542 Ma. However, according to a series of SHRIMP U-Pb dates from the late Precambrian in the Jiangnan Orogen Belt in South China Platform, the constrained strata will be redefined as in the upper part of the Qingbaikou System. To aid global geodynamics, it is useful to denote a late Precambrian section with unified, precise and high-precision chronological dating; this is here defined in North China Block and Jiaoliao-Korean Block. However, the Neoproterozoic Qingbaikou study in North China will be influence in whole Meso- and Neoproterozoic in the Jiangnan Orogenic Belt in between the Yangtze Block and the Cathaysia Block in South China. 相似文献
45.
示波极谱法测量电锌液中微量镍 总被引:1,自引:0,他引:1
提出在丁二酮肟-亚硝酸钠-氨水-氯化铵体系中,准确测定电锌液中微量镍的新方法:克服原子吸收光谱法测定微量镍回收率偏低问题。 相似文献
46.
47.
车仓峪钼矿位于小秦岭中生代娘娘山花岗岩体与太华群基底的接触带内,矿体发育在由一组X节理控制的石英脉内。本文对车仓峪钼矿开展了辉钼矿Re-Os定年以及黄铁矿微量元素LA-ICP-MS原位分析工作。所得辉钼矿Re-Os模式年龄为133.8±4.3Ma和132.7±2.2Ma,表明车仓峪钼矿的成矿年龄为早白垩世,与娘娘山岩体的成岩年龄一致。辉钼矿样品的Re含量较低,为83×10-6和86×10-6,指示了成矿物质可能来源于I型花岗岩——娘娘山花岗岩。对与辉钼矿共生的黄铁矿进行LA-ICP-MS微量元素原位分析,发现黄铁矿中Ni含量低(4.5×10-6~76.1×10-6,平均17.4×10-6),表明其来源应该是酸性岩,也就是其围岩娘娘山花岗岩。综合辉钼矿定年以及黄铁矿微量元素分析结果,车仓峪钼矿应该是早白垩世娘娘山花岗岩侵位时,由岩浆冷凝分异出的成矿流体充填和交代围岩形成。同时,小秦岭燕山期Mo矿化并不伴随Au矿化,结合已有资料,从侧面说明燕山期可能并不是小秦岭金的主成矿期。 相似文献
48.
《Geoforum》2015
This article examines changing water governance modalities in the context of the neoliberalization of nature. Specifically, it focuses on Brazilian water sector reforms passed in 1997 that mandate decentralized and participatory decision-making at the river basin scale. Critics have suggested that rescaling, decentralization, and participatory governance mechanisms – supposedly intended to render decision-making more equitable, accessible, and relevant – can serve to legitimate, facilitate, and thus further embed processes of neoliberalization. Examining the impact of Brazil’s water sector reforms on the state–society relationship, this article presents a case study of water governance in the São Francisco River Basin and finds that the reforms – despite their neoliberalizing potential – have not significantly contributed to the neoliberalization of governance therein. Instead, water governance continues to be characterized by longstanding patterns of traditional elite control. Through an institutional and socio-natural analysis, this article describes and accounts for the continued dominance of these patterns relative to neoliberalization and explores activists’ efforts to use water sector reforms to pursue more progressive possibilities. The article concludes with a discussion of the implications for variegation and contestation in ongoing debates over neoliberal natures. 相似文献
49.
智能型全站仪结合边角后方交会原理在高速铁路测量工作中得到广泛应用,其在CPⅢ高精度铺轨控制网的基础上进行自由重叠设站的精度能满足高铁测量的精度要求。在板式无碴轨道底板放样和轨道板安装时,可以根据仪器误差参数计算得出每个测站进行放样时误差不超限的最远放样距离,供测量人员参考。 相似文献
50.
对温度观测资料进行质量控制时,僵值和突变是常见的疑误类型,针对城市复杂环境中僵值和突变疑误数据进行研究,对降低城市自动站温度资料质量控制的误检率有重要价值。文章针对城市复杂环境(以上海世博园为例)中18个自动气象站一年(2010年5月至2011年4月)逐时温度资料进行质量控制,着重探讨僵值及突变疑误数据的分布特征和可能原因。结果表明:(1)僵值疑误数据集中出现在冬季夜间,局地性强。阴天或多云天气,通风不佳的测站感热项较小,易出现僵值过程,最长持续11 h。(2)温度突变疑误数据可分“突升”和“突降”两类,“突升”集中出现在秋冬季,而“突降”集中在春夏季;“突升”集中出现在日出前后,而“突降”主要出现在午后至夜晚,“突升”局地性强而“突降”各站间趋同性较强。分析发现,城市复杂环境下,日照突然增加或减少以及午后短时强降水是导致温度突变疑误数据的主要原因。因此,这些“疑误”数据是城市复杂环境影响或特定天气条件导致的,为真实有效的观测资料。针对城市复杂环境下的温度观测资料开展质量控制时,需结合观测环境等元数据进一步甄别。 相似文献