【摘要】 罗圈组为一套以杂砾岩为主的沉积建造广泛分布于华北地块南缘。本文对河南汝州罗圈组的杂砾岩沉积特征及其成因进行初步的探讨。在该套地层中见有大块的冰川漂砾及砾石表面的刻蚀痕迹等现象,推断该套地层形成的沉积环境与冰川作用相关。另外,层状杂砾岩及含砾纹泥岩中的砾石多为次棱角—棱角状,且对围岩的上、下层理具有明显的扰动,形成了具有"上凸下绕"形态的沉积构造,即坠石构造;在显微镜下砂级碎屑颗粒也见有此类坠石构造。砾石及砂级颗粒对其围岩层理的影响表明其为坠石构造,从而可指示罗圈组沉积期间具有冰筏沉积作用的存在。更多还原

【Abstract】 On southern margin of the North China Platform,the Luoquan Formation is characterized by the conglomerates. Based on the relationship between the gravels and the beddings around them,the geological causes of the Luoquan Formation were studied in this paper. The glacier boulders and the nicks on their surface,one of the tillite characteristics,were found in this formation. In the Luoquan Formation,the gravels in the conglomerates and the layered grain-mudstons generally show an angular or subangular. In addition,the beddings around the gravels and the sand-grade clasts are generally curved to show a dropstone-structure,indicating the existence of ice-rafting deposition. Therefore,the sedimentary environment of the Luoquan Formation was related to a glaciation.更多还原