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41.
Peixin Duan Cui Liu Xuanxue Mo Jinfu Deng Jinhua Qin Yu Zhang Shipan Tian 《地学前缘(英文版)》2018,9(5):1417-1431
The Chalukou porphyry Mo deposit, located in the Great Hinggan Range, is the largest Mo deposit in northeast China, although the age and genesis of the associated magmatic intrusions remain debated.Here we report zircon U-Pb ages and trace elements, whole rock geochemistry and Sre Nd isotope data with a view to understand the relationship between the magmatism and molybdenum mineralization.Zircon U-Pb analysis yield an age of 475 Ma for rhyolite in the older strata, 168 Ma for the premineralization monzogranite, and 154 Ma for the syn-mineralization granite porphyry. The granite porphyry and quartz porphyry are considered as the ore-forming intrusions. These rocks are peraluminous, alkali-calcic, and belong to high-K to shoshonitic series with a strong depletion of Eu. They also display characteristics of I-type granites. The rocks exhibit wide variations of(87 Sr/86 Sr)iin the range of 0.705426 -0.707363, and ε_(Nd)(t) of -3.7 to 0.93. Zircon REE distribution patterns show characteristics between crust and the mantle, implying magma genesis through crust-mantle interaction. The Fe_2O_3/FeO values(average 1) for the whole rock and EuN/Eu*Nvalues(average 0.45), Ce~(4+)/Ce~(3+) values(average 301)for zircon grains from the granite porphyry are higher than those from other lithologies. These features suggest that the ore-forming intrusions(syn-mineralization porphyry) had higher oxygen fugacity conditions than those of the pre-mineralization and post-mineralization rocks. The Chalukou Mo deposit formed in relation to the southward subduction of the Mongol-Okhotsk Ocean. Our study suggests that the subduction-related setting, crust-mantle interaction, and the large-scale magmatic intrusion were favorable factors to generate the super-large Mo deposits in this area. 相似文献
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LI Xianqing FENG Songbao XIAO Xianming TANG Yongchun XIAO Zhongyao MI Jingkui TIAN Hui LIU Dehan SHEN Jiagui 《中国地球化学学报》2013,32(2):157-169
The Kela-2 gas field, found in the Kuqa Depression of the Tarim Basin, northwestern China, is a large-sized dry gas field (C1 /C1-5 =0.992 0.999) and characterized by ultra-high pressure (pressure factor up to 2.0 2.2). The pyrolysis experiment was carried out under isothermal gold-tube closed system, with samples collected from the Jurassic coal, Jurassic mudstone and Triassic mudstone in the Kuqa Depression. The result of gas yield showed that the Middle and Lower Jurassic source rocks have higher gas generation potential than the Triassic source rocks. The kinetic modeling of gas generation and methane carbon isotope fractionation suggested that the Kela-2 gases belong to the products of high-over mature stages and were mainly derived from the Middle and Lower Jurassic coal-bearing strata. The Triassic source rocks made a minor contribution to the Kela-2 gases. The Kela-2 gases chiefly generated from coal-bearing source rocks with R o values from 1.3% to 2.5%, and thus primarily accumulated after 5 Ma. 相似文献
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瑞利波法检验客运专线湿陷性黄土地基处理效果 总被引:1,自引:0,他引:1
黄土地基具有明显的湿陷性,试验采用3种方法(柱锤冲扩桩、挤密桩、强夯)进行处理.测试得到地基在3种方案处理前后的瞬态瑞利波频散曲线,比较处理前后的瑞利波波速分布图,反演分析地基剪切波速度,得到黄土地基处理后的波速变化特性.结果表明,经3种方案处理后的黄土地基弹性波波速均得到了提高,波速增大幅度从大到小分别为柱锤冲扩桩、挤密桩和强夯,与静力触探法对比结果较为一致,表明瞬态瑞利波测试方法能大面积无损测试地基处理效果. 相似文献
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Guan Qing Yu Pan Bao Tian Li NaLi Qiong Zhang JundiGao Hongshan Liu Jia 《Comptes Rendus Geoscience》2010,342(3):189-196
Records of two loess sections located in mid-eastern and western margins of the East Asian Monsoon area captured 20 Dansgaard-Oescher events and six Heinrich events. All these suggested that the climate in the East Asian Monsoon area fluctuated rapidly on millennial to century timescales during the whole Last Glacial. We found that these loess-based events of rapid climate fluctuations were generally synchronous with those of GRIP records, but that there were differences between the Shagou loess section in the west and the Wangguan loess section in the east: the former was more sensitive to climate change than the latter. Compared with earlier studies on loess records covering the Last Glacial from neighboring areas, we discovered that the magnitude of Dansgaard-Oeschger cycles decreased gradually from west to east and we suggest that it resulted from the combined effect of the Westerlies and the East Asian Monsoon. 相似文献
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鳗鲡目鱼类线粒体基因组的基因组成较为保守,在58个线粒体基因组中,仅有3个物种存在基因数量的差异。在19个鳗鲡目鱼类线粒体基因组中存在主编码基因的重排。主编码基因的变异位点分析结果支持nad5、nad4和nad2基因作为cox1和lrRNA基因辅助的分子标记。鳗鲡科Anguillidae的20个种(亚种)聚在一起,强烈支持鳗鲡科为单系群(BPP=100)。鳗鲡科下属的3个类群(大洋洲类群、大西洋类群和印度洋-太平洋类群)也同时得到有力的验证(BPP均为100)。线鳗科Nemichthyidae和锯齿鳗科Serrivomeridae亲缘关系最近,二者聚类后,与鳗鲡科Anguillidae构成姊妹群(BPP=100)。在囊喉鱼亚目Saccopharyngoidei中,宽咽鱼科Eurypharyngidae与囊鳃鳗科Saccopharyngidae聚类(BPP=100),同时,单颌鳗科Monognathidae与月尾鳗科Cyematidae聚类(BPP=100),4个科聚在一支,支持囊喉鱼亚目为单系群(BPP=100)。在囊喉鱼亚目线粒体基因组中,3个物种(吞鳗Eurypharynx pelecanoides、拉文囊鳃鳗Saccopharynx lavenbergi和杰氏单颌鳗Monognathus jesperseni)存在主编码基因的重排。16种鳗鲡(细美体鳗Ariosoma shiroanago、短吻颈鳗Derichthys serpentinus、凯氏短尾康吉鳗Coloconger cadenati、鸭颈鳗Nessorhamphus ingolfianus、龟草鳗Thalassenchelys sp.、粗犁齿海鳗Cynoponticus ferox、百吉海鳗Muraenesox bagio、巨斑花蛇鳗Myrichthys maculosus、大吻沙蛇鳗Ophisurus macrorhynchos、几内亚副康吉鳗Paraconger notialis、哈氏异康吉鳗Heteroconger hassi、小头鸭嘴鳗Nettastoma parviceps、弱头鳗Leptocephalus sp.、斑点长犁齿鳗Hoplunnis punctata、尖吻小鸭嘴鳗Facciolella oxyrhyncha和星康吉鳗Conger myriaster),与鳗鲡目线粒体主编码基因的原始排列相比,共享nad6基因的易位。同时,基于线粒体基因组13个蛋白质编码基因构建的系统演化树,强烈支持这16个物种聚为一支(BPP=100)。然而,由此而带来的海鳗科Muraenesocidae、拟鯙科Chlopsidae和糯鳗科Congridae是否为单系群的问题,值得今后深入探究。 相似文献
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