北京十三陵中元古代串岭沟期地质事件的探索  

A Study of Geological Event Records in the Proterozoic Chuanlinggou Formation of the Ming Tombs District, Beijing

作　　者：宋天锐[1] 和政军[1] 丁孝忠[1] 张巧大[1] 

机构地区：[1]中国地质科学院地质研究所,北京100037

出　　处：《地质论评》2000年第4期400-406,共7页Geological Review

基　　金：国家自然科学基金 (编号4977212)

摘　　要：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、火山玻璃的假像、显微层内错位等。地球化学资料表明,Re、Os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生的。根据北京十三陵串岭沟组地质事件记录的研究,对比蓟县、宽城和曲阳等地的剖面后,笔者认为十三陵地区的串岭沟组相当于蓟县串岭沟组的上部层位。此外,串岭沟组出现火山—地震事件可能导致常州沟组后生动物遗迹化石的延续性被破坏;串岭沟组和常州沟组泥岩中有可能存在自生独居石,自生独居石为U,Th-Pb法同位素测年提供可能。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.

关 键 词：地质事件 元古界 串岭沟组 北京十三陵 

分 类 号：P534[天文地球—古生物学与地层学]