柴北缘与华北西缘中—新元古界地层对比及构造亲缘性分析

发布时间：2018-10-22 11:45

【摘要】：全吉地块是位于柴达木盆地北缘的一个微地块,其恰好处于华北板块、塔里木板块以及扬子板块的包围之中,大地构造位置尤为特殊。全吉群为发育在该地块变质结晶基底之上的一套中元古代稳定沉积盖层。从上世纪开始,不断有学者针对柴北缘的构造亲缘性提出了自己的认识,但由于缺乏可靠的同位素年龄支持或论据较单一难以令人信服,导致在该问题上始终莫衷一是,没有定论。其中最具代表性的一种观点认为:全吉地块是塔里木板块的一个裂解体,其在古元古界与华北板块相似,而在中-新元古界,则与扬子板块特征更加吻合。测年数据为地层划分以及构造亲缘性分析提供了很好的佐证。本文将实验测试数据与野外实测资料相结合,重点选择对柴北缘全吉山以及华北西缘阿拉善龙首山、宁夏贺兰山以及豫西等地区进行详细地质观测和研究。通过对上述区域的沉积序列、地层接触关系、火山事件层以及特殊标志层(冰碛砾岩层与含磷层)等几方面展开对比分析,最终确认了柴北缘与华北西缘在中-新元古界时期存在着较高的构造亲缘性和古环境相似性,而非对比扬子板块,其盖层沉积的形成和岩石组合特征可能响应了哥伦比亚(Columbia)超大陆的裂解作用。
[Abstract]:Quanji block is a microblock located in the northern margin of Qaidam basin, which is surrounded by North China plate, Tarim plate and Yangtze plate, especially in the tectonic position. Quanji Group is a set of Mesoproterozoic stable sedimentary caprocks developed on the metamorphic crystalline basement of the block. Since the beginning of the last century, many scholars have put forward their own understanding on the tectonic kinship of the northern margin of Qaidam. However, due to the lack of reliable isotopic age support or the fact that the argument is relatively simple and unconvincing, there has always been disagreement on this issue. There is no conclusion. One of the most representative views is that the Quan Ji block is a pyrolysis of the Tarim plate, which is similar to the North China plate in the Paleoproterozoic, while in the Meso-Neoproterozoic, it is more consistent with the characteristics of the Yangtze plate. The dating data provide good evidence for stratigraphic classification and structural phylogenetic analysis. In this paper, the experimental data are combined with the field data, and the detailed geological observation and study are carried out on the northern margin of Qaidam, the western margin of North China, the Alashan Longshou Mountain, the Helan Mountain of Ningxia and the west of Henan Province. The sedimentary sequence, stratigraphic contact relationship, volcanic event layer and special marker layer (moraine conglomerate layer and phosphorous layer) in the above mentioned areas are compared and analyzed. Finally, it is confirmed that the northern margin of Qaidam and the western margin of North China had relatively high tectonic affinity and paleoenvironmental similarity in the Meso-Neoproterozoic period, rather than contrasting the Yangtze plate. The formation of caprock sediments and the characteristics of rock assemblages may respond to the fragmentation of the (Columbia) supercontinent in Colombia.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P534.3;P542

【相似文献】