华北克拉通古/中元古代界线和相关地质问题讨论  

The Paleoproterozoic-Mesoproterozoic boundary of the North China Craton and the related geological issues: A review

作　　者：赵太平[1,2] 邓小芹[2,3] 胡国辉[4] 周艳艳[5] 彭澎[5] 翟明国[1,5] 

机构地区：[1]西北大学大陆动力学国家重点实验室,西安710069 [2]中国科学院广州地球化学研究所矿物学与成矿学重点实验室,广州510640 [3]中国科学院大学,北京100049 [4]中国地质科学院地质力学研究所,北京100081 [5]中国科学院地质与地球物理研究所岩石圈演化国家重点实验室,北京100029

出　　处：《岩石学报》2015年第6期1495-1508,共14页Acta Petrologica Sinica

基　　金：国家重点基础研究发展计划973项目(2012CB416606);西北大学大陆动力学国家重点实验室开放课题的联合资助

摘　　要：从18到16亿年,全球构造格局、古地理环境及生物演化发生重要变革。就全球地质演化历史而言,结晶基底的形成标志着古元古代的结束,而稳定盖层的发育标志着中元古代的开始。在国际地层年表上,古元古代末期（18-16亿年）被称之为＂固结纪＂,古/中元古代的界线被划定在16亿年。在华北克拉通,一般认为＂吕梁运动＂是结晶基底最终形成的标志性构造-热事件,此后发育以长城系为代表的地台型沉积盖层。长期以来,我国地质界一直以长城系的沉积代表中元古代的开始,并将古/中元古代的界限置于18亿年,与国际地层年表相差2亿年,以至于在中外文献中对中国18-16亿年间的地质记录的表述方式混乱。究其原因,主要有：1华北克拉通基底的形成或最终克拉通化是以＂吕梁运动＂的结束为标志,结晶基底最晚期的变质年龄不晚于18亿年;2长城系的底界年龄（18亿年）一直缺乏可靠的数据,目前对华北克拉通范围内稳定盖层发育的起始时间及代表性沉积记录,尚无统一的认识;3对华北克拉通由基底形成到盖层的演化及构造体制转折的动力学过程等见解不一,也缺少精细的年代学制约。本文综述了华北克拉通尤其是南部地区18-16亿年岩浆-沉积记录的研究进展,就古/中元古代界线及相关地层对比和划分方案进行了讨论,并指出了亟需解决的重要科学问题。作者认为：1华北克拉通18-16亿年的火山-沉积记录在其南部地区最广泛、最完整。其中,熊耳群火山岩系（18-17.5亿年）,包括底部发育的河湖相砂岩-泥岩沉积——大古石组,早于蓟县剖面的长城群,是华北陆块结晶基底形成后最早的盖层沉积。2华北克拉通古/中元古代的分界年龄目前有2种选择：一是18亿年,即熊耳群火山岩系底部大古石组的起始沉积年龄;二是16亿年,将蓟县剖面长城系的高于庄组划归蓟县系,长城系的1. 8 - 1. 6Ga is a period when the planet Earth witnessed a critical revolution in global tectonic configuration,paleogeographic environment and biological evolution. The formation of the crystalline basement represents the end of the Paleoproterozoic,whereas the development of stable sedimentary covers represents the start of the Mesoproterozoic. The Late Paleoproterozoic（ 1. 8 - 1. 6Ga） is referred as the ＂Statherian ＂ in the international chronostratigraphic chart,and the boundary between the Paleoproterozoic and the Mesoproterozoic is inferred at 1. 6Ga by the International Commision on Stratigraphy（ ICS）. In the North China Craton（ NCC）,the＂Lvliang Movement＂was usually considered to be a significant tectono-thermal event marking the final generation of the crystalline basement,which was followed by the development of platform-type sedimentary covers represented by the Changcheng System. Most Chinese geologists take the deposition of the Changcheng System represents the beginning of the Mesoproterozoic in China at 1. 8Ga,some 200 Myr older than the age proposed by ICS. The expressions of the geological records between 1. 8Ga and 1. 6Ga are confusing in both domestic and international literatures. This confusion arises as there are different viewpoints： 1） The formation of the crystalline basement of the NCC or its final amalgamation is marked by＂the Lvliang Movement＂,and the metamorphic age of the crystalline basement is no later than 1. 8Ga; 2） Although many researchers believe that the bottom boundary age of the Changcheng System is 1. 8Ga,the starting time of stable sedimentary cover and representative sedimentary records in the NCC vary in different region; 3） The geodynamic evolution in the NCC and its tectonic transition from basement formation to stable sedimentary cover development are controversial,besides,previous studies also lack precise geochronological constraints. In this paper,we review the progresses in the study of magmatic and sedimentary records in the NCC,e

关 键 词：华北克拉通 古/中元古代界限 中元古代地层划分方案 长城系 熊耳群 高于庄组 大红峪组 大古石组 

分 类 号：P534[天文地球—古生物学与地层学]