【作者】 孙玉建；

【导师】 张传恒；

【作者基本信息】 中国地质大学（北京） ， 古生物学与地层学， 2003， 硕士

【摘要】 Grenville期造山带存在于中晚元古代，是连接Rodinia各陆块的纽带。扬子陆块在Rodinia中的位置是近几年来的热点问题，愈来愈多的证据显示它的褶皱基底是Grenville期造山带的重要组成部分，盐边群是扬子陆块褶皱基底的组成部分，研究它的地质特征和大地构造属性，可以为研究扬子陆块在Rodinia中的位置提供重要的地质线索。 在野外和室内仔细工作的基础上，本文在以下四个方面取得了进步： 1．基于对盐边群中、小尺度变形构造进行构造解析，建立了区域构造格架，通过对褶皱枢纽和劈理的分析，提出盐边群第一期透入性变形构造的走向为北东东—南西西向。 2．根据新的区域构造格架和野外连续露头的叠覆关系，重新厘定了盐边群碎屑岩的地层序列以及各碎屑组的内含。 3．通过岩石特征和地球化学分析，确定了盐边群荒田组火山岩组合为洋脊玄武岩、洋岛玄武岩、洋岛安山玄武岩系列，说明这是洋壳残片，即典型的蛇绿岩套。经过初步的侵位机制分析，可知这套火山岩经历了海沟增生楔、弧前盆地基底，并接受了盐边群碎屑岩的沉积。 4．盐边群碎屑岩碎屑骨架颗粒统计分析结果和砂岩常量元素构造环境判断图解显示，它们所处的构造环境为活动大陆边缘，初步判定它们的原型盆地为弧前盆地。 基于以上结论，讨论了Grenville期造山带在康滇地区存在的可能性及其可能的展布走向，进而讨论了扬子陆块在Rodinia中可能的位置。更多还原

【Abstract】 The Grenville-aged orogen is a tie to link most of the continental blocks in Rodinia, which existed during the period from late Mesoproterozoic through early Neoproterozoic. The position of Yangtze Block in Rodinia have been warmly discussed in the recent years. More and more evidences suggest that the fold basement of Yangtze Block is an integral part of the Grenville-aged orogen. The Yanbian Group, which resulted from post-Grenville orogen, outcrops in the Panzhihua area, Sichuan province. Hence, the studies on the geological features and geotectonic implications of the Yanbian Group can provide some clues to refine the position of Yangtze Block in Rodinia.Based on the field working and lab analysis, the following conclusions were made:1. The anatomy of small-scale to meso-scale deformational structures have resulted in the reconstruction of the structural framework of the Yanbian Group. The statistical analyses of the fold hinge and cleavages developed in the Yanbian Group suggest the trend of the first stage penetrating structures of the Yanbian Group is EEN-WWS.2. Based on the new structural framework and the overlap relationships in every continuous outcrop, the new stratigraphic sequence of the Yanbian Group is put forward, which deeply changes the rock composition of every formation.3. The analysis of the geochemical and petrologic characteristics features shows that the assemblage of volcanic rocks is the series of middle ocean ridge basalt, ocean island basalt and ocean island andesite basalt, which implies that it is the relic of the ocean crust, i.e. typical ophiolites. The primitive study on the emplacement mechanism suggests that the volcanic rocks had underwent the stages of the trench accretion and the basement of forearc basin, which received the elastics of the Yanbian Group.4. Triangular diagram of the sandstone clastic compositions and the relationship diagram of major element suggest that the proto basin of the clastic rock of the Yanbian Group was a forearc basin, which was in an active continental margin.Based on the above conclusion, the regional expression of the Grenville-aged orogen in the Kangdian Area and orogenic architecture is also discussed, and the refining position of Yangtze Block in Rodinia is proposed更多还原