摘要
以国家油气资源战略选区项目研究成果为基础,结合近年来该区积累的大量区域地质调查资料和已发表的数据,对东北及内蒙古东部地区早古生代以来的大地构造性质及其演化进行综合对比分析。东北地区晚古生代以来的构造演化以稳定的大陆地块为主体,而非两大板块间多岛洋演化形成的造山带。东北地区的各地块均具有前寒武纪—早前寒武纪、甚至是太古宙的古老基底,它们在早古生代早期(490~510Ma)同时遭受了区域变质作用和花岗质岩浆侵入。350~450Ma,各地块均处于相对稳定的构造环境,以普遍缺失这一时期的花岗质岩浆活动记录为标志。从早古生代晚期开始,东北及内蒙古东部地区至少已存在2个早古生代早期固结的微陆块,即额尔古纳—兴安微陆块和松嫩—佳木斯微陆块,这2个微陆块向北分别与俄罗斯境内的额尔古纳微陆块和布列亚微陆块相连。二者在早石炭世沿北北东向展布的开鲁—嫩江—黑河—诺拉—索霍提(Nora-Soukhotin)一线碰撞拼合,形成统一的东北亚晚古生代大陆板块。西拉沐伦河断裂西端被北北东向构造所截,向东延至开鲁—嫩江断裂,并没有延伸到松辽盆地内,说明西拉沐伦河断裂可能与开鲁—嫩江碰撞带的形成有关。从晚石炭世开始,东北亚大陆板块整体处于伸展构造背景,至少在中国境内具有北陆南海的构造-沉积古地理格局,早期发育以火山岩为主的断陷盆地,到中二叠世演化成一个规模巨大的海相沉积盆地。中生代以来,东北地区的构造体制转换及物质成分演化不仅仅是古亚洲洋构造域和西太平洋构造域叠加转换的结果,蒙古—鄂霍茨克构造域的演化对该区现今构造体制的形成也具有重要影响。地质和地球物理综合证据显示,大兴安岭北部的得尔布干断裂、内蒙古中部的贺根山断裂和黑龙江省东部的跃进山断裂可能并不是具有一定深度规模的构造分区断裂。东北地区的中、新生代盆地之下并非都是变质结晶基底,而是存在一个规模巨大的晚古生代海相沉积盆地。
The authors accumulate a large amount of new data of regional geology and geochronology in recent years and makes a generalization and summation of the tectonic nature and evolution in Northeastern China.A comprehensive study indicates that the NE China continent is composed mostly of relatively stablae massifs,rather than orogenic belt since Late Paleozoic.All of these massifs include the basements of Precambrian-Early Precambrian,even Archean,and were simultaneously subjected to metamorphism and granitic magmatism in early Early Paleozoic(490-510 Ma).During 350-450 Ma,at least two stable microcontinents of Erguna-Xing'an and Songnen-Jiamusi composed of massifs solidified in 490-510 Ma existed in NE China,marked by without magmatism,which are northwards linked together with Erguna and Buriya massifs in Russia,respectively.These two microcontinents collided together along a NNE-trending Kailu-Nenjiang-Heihe(NE China)-Nora-Soukhotin(Russia) in Early Carboniferous and formed a Northeast Asia continental plate(NACP).The well-known Xilamulunhe fault is commonly referred as a final collision zone between NACP and North China plate,but the west end of the fault is cut by NNE-trending fault,and east end linked together with Kailu-Nenjiang collision zone and not stretches eastwards into Songliao basin,indicating the Xilamulunhe fault is possibly related to the formation of Kailu-Nenjiang collision zone.From Late Carboniferous to Mid Permain,the NACP on the whole was at extension setting where at least in NE China,a series of faulted basins with predominant volcanics formed in early time and a large marine sedimentary basin formed in Mid Permian.All of the Late Paleozoic volcanics and sedimentary rocks do not suffer regional metamorphisam.The transformation of Mesozoic tectonic regime in NE China is related not only to superposition and transformation of Paleo-Asia ocean tectonic system by west Pacific tectonic system,but the evolution of Mongolia-Okhotsk tectonic system plays an important role in transforming tectonic regim,especially in Mid-Late Jurassic.The evidences of geology and geophysics show that the well-known three faults of Derbugan in Da-Xinganling Mountains,Hegenshan in central part of Inner-Mongolia and Nadanhada in east part of Heilongjiang Province are not deep faults controlling tectonic units probably.The parts under Mesozoic-Cenozoic basins in NE China for the most part are not metamorphosed crystalline basement,but a large marrine sedimentary basin.
出处
《吉林大学学报(地球科学版)》
EI
CAS
CSCD
北大核心
2012年第5期1269-1285,共17页
Journal of Jilin University:Earth Science Edition
基金
国家油气战略选区专项(14B09XQ1201)
国家自然科学基金重点项目(40739905)
国家深部探测专项项目(SinoProbe-02-04)