北京十三陵中元古代串岭沟期地质事的探索

宏观、微观和地球化学研究结果证明在北京十三陵中元古界长城系串沟组有地质事件层。宏观标志包括一系列地震滑塌、砂体液化、层内错断和角砾化构造等；微观标志包括火山晶屑，火山玻璃的假象，显微层内错位等。地球化学资料表明，Ｒｅ、０ｓ及其同位素和Ｉｒ含量异常，某些稀有元素含量的对比等等，都有可能说明地质事件引起了异常现象的出现，笔者认为串岭沟组的地质事件是由于燕山裂陷槽形成早期的火山活动及由其引发的地震事件产

A Studyof Geological Event Records in the ProterozoicChuanlinggou Formation of the Ming Tombs District, Beijing

A geological event set in the middle part of the Chuanlinggou Formation was demonstrated by a series of macroscopic, microscopic, and geochemical records. The macroscopic event structures include interformational slumps and faults, sand-liquefaction, carbonate brecciation etc. ; the microscopic ones include micro-fault, micro-liquefaction veinlets, pyroclastic crystals, and pseudomorphs of tuff glass etc. Earthquake shocking induced all of above events, which are interpreted in this paper as a result of volcanic eruption. Besides, there are abnormal geochemical records such as Re, Os, Ir as well as other rare elements in black silty mudstones or shales of the Chuanlinggou Formation. The geological event records in the Chuanlinggou Formation give a clue to interpret the interruption of so-called oldest metazoan trace fossils from the overlying Changzhougou Formation. Besides, this paper suggests that an authigenic rare earth element mineral-monazite might be found from the Chuanlinggou and Changzhougou Formations according to the anomalously high Ce content because the authigenic monazite has been already discovered from the Precambrian mudstone of the Dalian area. The discovery of authigenic monozite provides a possibility for isotopic age determination by using the U and Th-Pb methods. The authors of this paper hold that the Chuanlinggou Formation of the Ming Tombs District of Beijing corresponds to the upper part of the Chuanlinggou Formation of the Jixian section of Tianjin.