北京下苇甸地区新元古代景儿峪组–寒武纪府君山组界线硅质角砾形成模式  

Formation of Chert Breccia from the Transitional Beddings between Neoproterozoic Jingeryu Formaiton and Cambrian Fujunshan Formation in Xiaweidian Section,Beijing

作　　者：李辰卿 董琳 沈冰 LI Chenqing;DONG Lin;SHEN Bing(Key Laboratory of Orogenic Belts and Crustal Evolution(MOE),School of Earth and Space Sciences,Peking University,Beijing 100871)

机构地区：[1]造山带与地壳演化教育部重点实验室,北京大学地球与空间科学学院,北京100871

出　　处：《北京大学学报（自然科学版）》2023年第3期415-426,共12页Acta Scientiarum Naturalium Universitatis Pekinensis

基　　金：国家自然科学基金(41402025)资助。

摘　　要：为探讨华北板块在新元古代与寒武纪之间沉积间断后再次接受沉积的具体过程和环境变化,选取北京西山地区下苇甸剖面青白口系景儿峪组和下寒武统府君山组的硅质沉积作为研究对象,通过沉积学、岩石学及地球化学分析,发现景儿峪组顶部硅质层及府君山组底部硅质条带角砾具有相似的接近海水的Ge/Si比值和稀土配分特征,揭示府君山组硅质条带角砾可能来自下伏景儿峪组。研究结果还表明,府君山组底部含角砾白云岩不具有层理,且其中角砾成分复杂,磨圆分选程度较低,排列杂乱,可能代表一次冰川沉积。To investigate the specific processes of deposition and environmental changes in the North China Block during Late Neoproterozoic to Early Cambrian when it received deposition again after a depositional hiatus,chert breccia of the Qingbaikou Series Jingeryu Formation and the Lower Cambrian Fujunshan Formation in the Xiaweidian section of Xishan area of Beijing was analyzed.Based on petrological and geochemical studies,chert layers in Jingeryu Formation and chert breccia in the bottom of the overlying Fujunshan Formation have similar Ge/Si ratios and rare earth element patterns.It indicates that Fujunshan chert breccia might originated from Jingeryu Formation.Breccia-bearing dolomite in the bottom of the Fujunshan Formation is block-shaped,without bedding.The breccia is mixed in component and size,with poor sorting and roundness,and disorderly arranged.Breccia-bearing dolomite in the bottom of Fujunshan Formation may represent glacial deposits.

关 键 词：景儿峪组 府君山组 古风化壳 GE/SI 稀土元素 

分 类 号：P512.13[天文地球—地质学] P595P534