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Characteristics of the middle-Late triassic sedimentary facies assemblages in the Songpan-Ruoergai area

Progress in Natural Science:Materials International 2007年第3期17卷 305-313页

作者： YAN Zhen, YU Liangjun, LI Jiliang, BIAN Qiantao, WANG Zongqi and YANG Yongcheng ( Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China Shaanxi Insititute of Geology Survey, Xianyang 712000, China) Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Shaanxi Insititute of Geology Survey Xianyang 712000 China

The middle-Late triassic sedimentary rocks in the Songpan-Ruoergai area mainly consist of calcareous siltstone, muddy limestone, lithic arkose, feldspathic litharenite, mudstone, wormkalk, oolithic limestone, and conglomerate. Except for limestone bed increasing eastward longitudinally and vertically, the calcareous component of the sandstones increases obviously. Abundant benthic and plant fossils and their clasts occur within these rocks. The sedimentary structures predominately contain flaser, parallel, tabular, wavy, and herringbone cross beddings. These data coevally imply that the middle-Late triassic sediments deposited in the fluvial, lake and tide environments. Additionally, the rocks display graded, parallel, hummocky beddings, and sandy lamination, a feature characteristic of storm deposits.

关键词： middle-upper triassic fluvial-lake environments tide environment tempestite Songpan-Ruoergai

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Discowry of Cosmic Dust in Gold Deposits in Northwestern Sichuan and Its Significance

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Acta Geologica Sinica(English Edition) 1995年第4期69卷 396-405,448页

作者： Zheng M inghua, Zhou Yufeng, Fu Reaping Department of Mineral Resources, Chengdu University of Technology, Chengdu, Sichuan Fei Zhenbi

In recent years, a considerable amount of microscopic spherules have been found in concentrates recovered from some stratabound gold deposits occurring in middle-upper triassic turbidite series in northwestern Sichuan. Study indicates that these spherules are cosmic dust. It is the first time that cosmic dust of extraterrestrial origin has been found in hydrothermal gold deposits in *** spherules are steel-grey in colour and show metallic luster. Their grain size is commonly less than 100 μm. According to their composition, they belong to chromium-rich iron cosmic dust. The spherules have complex and diverse microscopic structures and textures, i.e. they show a very distinct Widmanstaten *** variation of cosmic dust content in gold deposits exhibits a positive correlation with the mineralization intensities and hydrothermal alteration. Such a relation indicates that the ore sub- stances may transport not only mechanically but also may chemically in hydrothermal solutions.

关键词： gold deposit cosmic dust northwestern Sichuah middle-upper triassic

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