This paper reports a newly discovered Late Mesoproterozoic-Early Neoproterozoic stromatolite assemblage, named here the "Jiawengmen stromatolite assemblage", represented by a Conophyton-Baicalia association in the J...This paper reports a newly discovered Late Mesoproterozoic-Early Neoproterozoic stromatolite assemblage, named here the "Jiawengmen stromatolite assemblage", represented by a Conophyton-Baicalia association in the Jiawenmen area in the southern belt of the Eastern Kunlun. This stromatolite assemblage is dominated by large-scale conical stromatolites and related elements, i.e., Conophyton garganicus var. inkeni, C. cf. ressoti Menchikov, Jacutophyton cf., Conicodomenia f., which commonly co-exist with elements of the group of Baicalia. This assemblage can be correlated with that of the middle Jixian-middle Qingbaikou System in North and Northwest China, but is different from that in South China. Correlation can also be made with that in the upper horizon of the Middle Riphean-lower horizon of the Upper Riphean in the South Ural Mountains and Siberia of Russia, in North Africa, and in the Alaskan Peninsula of North America. These facts suggest that the Jiawengmen stromatolite assemblage probably colonized during 1300-850 Ma ago. Accordingly, the stromatolite-bearing carbonate rocks are then proposed to correspond to the middle Jixian System-middle Qingbaikou System or the upper Middle Riphean-lower Upper Riphean. Our stromatolite data further suggest that a Precambrian microblock, named the Xialawen microblock here, occurred in the southern belt of Eastern Kunlun, the western part of the Maqên microblock. Similar stromatolite assemblages in the Maqên microblock and those blocks that occurred in North China, Siberia and North Africa point to similar paleogeographic and paleoenvironmental conditions. These microblock and blocks were probably located at low latitudes and on the continental margins of the Rodinian supercontinent, where warm epicontinental seas were favorable to widespread colonization of stromatolites during the Late Mesoproterozoic-Eady Neoproterozoic. However, these stromatolite assemblages are quite different from those of the South China block, which is suggestive of different paleogeographic contexts, and probably also of a different tectonic affinity.展开更多
矿产资源保障能力不仅是矿产资源开发利用程度对国家经济发展支撑能力的反映,也是资源安全程度的重要体现。为了科学地分析评价我国矿产资源保障能力,文章从资源禀赋、国内供需、国际市场三方面构建矿产资源保障能力指标体系,形成包含...矿产资源保障能力不仅是矿产资源开发利用程度对国家经济发展支撑能力的反映,也是资源安全程度的重要体现。为了科学地分析评价我国矿产资源保障能力,文章从资源禀赋、国内供需、国际市场三方面构建矿产资源保障能力指标体系,形成包含三类基本指标十种要素指标的体系框架,建立熵权TO P S IS模型矿产资源保障能力评价方法,并以锰矿为例,对我国锰矿资源保障能力进行评价与分析。结果表明,2009—2018年我国锰矿资源保障能力经历了较安全、基本安全、较危险三个阶段,总体呈下降趋势。展开更多
基金This work was supported by the KIP Key Project of the Chinese Academy of Sciences(KZCX3-SW-143)the KIP Key Project of the Chinese Academy of Sciences(KZCX2-SW-119)+3 种基金the Key Project of the National Natural Science Foundation of China(Grant No.40334044)the Chinese National Key Basic Research Project(2002CB4 12600)the National Natural Science Foundation of China(Grant No.49872077)the Lu Jiaxi Foundation of the Chinese Academy of Sciences.
文摘This paper reports a newly discovered Late Mesoproterozoic-Early Neoproterozoic stromatolite assemblage, named here the "Jiawengmen stromatolite assemblage", represented by a Conophyton-Baicalia association in the Jiawenmen area in the southern belt of the Eastern Kunlun. This stromatolite assemblage is dominated by large-scale conical stromatolites and related elements, i.e., Conophyton garganicus var. inkeni, C. cf. ressoti Menchikov, Jacutophyton cf., Conicodomenia f., which commonly co-exist with elements of the group of Baicalia. This assemblage can be correlated with that of the middle Jixian-middle Qingbaikou System in North and Northwest China, but is different from that in South China. Correlation can also be made with that in the upper horizon of the Middle Riphean-lower horizon of the Upper Riphean in the South Ural Mountains and Siberia of Russia, in North Africa, and in the Alaskan Peninsula of North America. These facts suggest that the Jiawengmen stromatolite assemblage probably colonized during 1300-850 Ma ago. Accordingly, the stromatolite-bearing carbonate rocks are then proposed to correspond to the middle Jixian System-middle Qingbaikou System or the upper Middle Riphean-lower Upper Riphean. Our stromatolite data further suggest that a Precambrian microblock, named the Xialawen microblock here, occurred in the southern belt of Eastern Kunlun, the western part of the Maqên microblock. Similar stromatolite assemblages in the Maqên microblock and those blocks that occurred in North China, Siberia and North Africa point to similar paleogeographic and paleoenvironmental conditions. These microblock and blocks were probably located at low latitudes and on the continental margins of the Rodinian supercontinent, where warm epicontinental seas were favorable to widespread colonization of stromatolites during the Late Mesoproterozoic-Eady Neoproterozoic. However, these stromatolite assemblages are quite different from those of the South China block, which is suggestive of different paleogeographic contexts, and probably also of a different tectonic affinity.
文摘矿产资源保障能力不仅是矿产资源开发利用程度对国家经济发展支撑能力的反映,也是资源安全程度的重要体现。为了科学地分析评价我国矿产资源保障能力,文章从资源禀赋、国内供需、国际市场三方面构建矿产资源保障能力指标体系,形成包含三类基本指标十种要素指标的体系框架,建立熵权TO P S IS模型矿产资源保障能力评价方法,并以锰矿为例,对我国锰矿资源保障能力进行评价与分析。结果表明,2009—2018年我国锰矿资源保障能力经历了较安全、基本安全、较危险三个阶段,总体呈下降趋势。