论文部分内容阅读
鄂东南位于江南造山带中部区段,是扬子地块与华夏地块结合带,自东向西从明确到争议的过渡区域,区内新元古界冷家溪群顶部普遍发育一套含砾层位——大药菇组。调查发现,通山小洞剖面是研究冷家溪群顶部层位的理想剖面,剖面中大药菇组可分为上下两个岩性段:下段以含砾层为主,结合药菇山剖面可将大药菇组砾岩分为五种类型;上段以粉砂质板岩为主。碎屑锆石研究表明大药菇组至少形成于~826 Ma之后,甚至有可能略晚于820 Ma,与武陵运动的年龄范围十分接近,说明大药菇组沉积时限短,为近源快速堆积的产物,结合沉积特征的研究,认为大药菇组下段的砾岩以斜坡碎屑流沉积为主,而非前人认为的浊积物。相对而言,小洞剖面的大药菇组沉积于斜坡之上,碎屑流沉积占主导地位;药菇山剖面的大药菇组沉积更靠近坡底,浊流沉积比重略有增加。
Southeast of Hubei is located in the central section of the Jiangnan orogenic belt and is a transition zone from the clear-to-controversial zone that is a combination belt of the Yangtze block and the Huaxia block. The top of the Lengjuxi Group in the Neoproterozoic in the area generally develops a set of gravel Horizons - large mushroom group. The survey shows that Tongshan Cave is the ideal section for studying the top layer of the Lengjiaxi Group. There are two lithologic sections in the section: the lower part is dominated by gravel layer, Large mushroom group conglomerate can be divided into five types; the upper part of the main silty slate. Detrital zircons study showed that the group formed at least after 826 Ma, and may even be slightly later than 820 Ma, very close to the age range of the Wuling movement, indicating that the sedimentary period is short, the rapid accumulation of near-source Based on the study of sedimentary characteristics, it is concluded that the conglomerate in the lower part of the Lvzhugu Formation is dominated by slope debris flow, rather than the turbidity sediments previously thought. Relatively speaking, the large group of mushrooms in the small cave sediments are deposited on the slope, and the debris flow deposition dominates. The large mushroom group in the section of Yutu Mountain is deposited closer to the bottom of the slope, and the turbidity flow sediment proportion slightly increases.