华北地台南缘苏-鲁-皖地区中-新元古界的重新划分与对比  

Redivision and Correlation of Meso-Neoproterozoic Strata in the Jiangsu-Shandong-Anhui Area, Southern margin of North China Block

作　　者：牛绍武[1] 辛后田 林晓辉[1] 

机构地区：[1]中国地质调查局天津地质调查中心,天津300170

出　　处：《地质调查与研究》2013年第3期161-172,共12页Geological Survey and Research

基　　金：全国地层委员会项目:中国主要断代地层建阶研究(200113900076);中国地质调查项目:晋冀成矿区地质矿产调查(1212011085296)

摘　　要：近些年来，燕山地区青白口系下马岭组斑脱岩锆石SHRIMP法U-Pb测年获1366～1380 Ma,下马岭组的时代已属中元古代。华北地台南缘苏-鲁-皖地区与下马岭组相当的地层当属徐淮群上部史家组至望山组，也有属中元古代的可能。淮北地区出露大面积的基性岩墙群，并侵入于徐淮群中,辉绿岩单颗粒锆石SHRIMP法U-Pb年龄为976土24～1038土26 Ma，徐淮群的时代显然老于该年龄。据此，苏-鲁-皖地区“青白口系至震旦系”的地层格架应重新进行划分与对比。结合宏观藻类化石Chuaria-Tawuia组合与蠕形类化石Pararenicola-Paleolina组合等资料，笔者将本区原“青白口系至震旦系”的地层重新划分为中元界长城系-蓟县系的徐淮群下部,金州系的徐淮群上部,新元古界下部的淮南群和新元古界上部的南华系。本区凤台组冰碛岩与劳伦古陆西缘750 Ma的拉皮坦群冰碛层似可对比；与五岗集组相当的陕西罗圈组上段泥质岩Rb-Sr年龄为722 Ma；凤台组冰碛层出现古磁极倒转，与扬子地台也有磁极倒转的古城组冰碛层大体相当，围干组-凤台组-五岗集组分别可与扬子地台的莲沱组-古城组-大塘坡组对比，其时代应划归南华纪为宜。据此，笔者全面调整了苏-鲁-皖区中-新元古界的划分与对比，并首次将华北地台南缘的冰碛层划归南华系下部，实现了华北地台与扬子地台南华系的直接对比与衔接，初步解决了华北地台与扬子地台南华系-震旦系长期悬而未决的重大地层对比问题，为重新建立我国以蓟县剖面为代表的中-新元古界地层格架提供了坚实的地层基础，此建议无疑具有重要的地层学意义和地质年代学意义。另外，该区新元古界亦可与劳伦古陆加拿大新元古界麦肯齐山超群-铜旋回和拉皮坦群冰碛层对比，进一步表明华北地台与劳伦古陆曾处在Rodinia超大陆范围内的可能。The Late Precambrian strata of Su-Lu-Wan（Jiangsu-Shandong-Anhui Provine） area is divided from lower to upper into the Huainan Group,Xuhuai Group and Suxian Group in Southern margin of North China Block. It is the Neoproterozoic Era in age. According to the stromatolites Linella-Gymnosolen-Katavia assem-blage and present reported new U-Pb ages （SHRIPM）, the Shijia Formation and Wangshan Formation of the up-per part of the Xuhuai Group may be correlated with Xiamaling Formation with a weighted mean 206Pb/U238 of 1368~1370 Ma in Yanshan Mountain area,northern China. Therefor, the Shijia Formation and Wangshan Forma-tion is of Late Mesoproterozoic Era in age. The lower part of Xuhuai Group with the stromatolites Conophy-ton-Baicaliaassemblage may be correlated with Luda Group and Gezhenpu Group in Southern Liaodong Peni-sula, Liaoning Province, China. So, it is Early-Middle Mesoproterozoic in age. Further SHRIMP U-Pb dates of 976土24 Ma（206Pb/238U） and 1038土26 Ma（207Pb/206Pb） were gained from the diabase rock in the Neoproterozoic strata in the Xu-Huai area, which indicates the origin of the Neoproterozoic magma and it is also proved that there was a great scale basic magmatic active developed in the southeastern margin of the North China Block, which can be correlated with the intrusive magma events of the Grenvillian orogenic episode in Northern Ameri-can, Mid-Africa and Easthern Greenland. So, Xuhuai Group and Suxian Group is the Neop-roterozoic Era in age in the southern margin of Northern China Block. Neoproterozoic strata is divided into Huainan Group of the low-er part of Neoproterozoic and Nanhua System of the upper part of Neoproterozoic in Su-Lu-Wan district, south-ern margin of Northern China continent. Huainan Group is divided from lower to upper into Caodian（曹店） For-mation, Bagongshan Formation, Liulaobei Formation, Shouxian Formation, Jiuliqiao Formation and Sidingshan Formation. It is of the early Neoproterozoic in age. Nanhua System is divided into Weigan Formation, Fengtai

关 键 词：华北地台 苏－鲁－皖地区 中－新元古界 划分与对比 

分 类 号：P534.3[天文地球—古生物学与地层学]