摘要
一些学者提出华北克拉通在新元古代早期之前与圣弗朗西斯科克拉通（圣弗朗西斯科一刚果克拉通）相邻，但缺少证据；本文总结两个古陆地质记录，为评价这一古构造格局模型提供线索。两个古陆陆壳生长的峰期均为-2．7Ga前；不同之处是，华北古陆经历了显著的-2．5Ga前的陆壳生长和改造，而圣弗朗西斯科克拉通则似乎没有。华北古陆2．4—2．2Ga期间发育少量变质火山-沉积岩系和花岗岩，-2．1Ga前后广泛发育裂谷火山一沉积建造及侵入岩，2．0—1．9Ga发育超高温变质作用和类似弧岩浆活动，导致两个克拉通（东、西华北克拉通）拼合形成统一的华北古陆；同一时期，圣弗朗西斯科克拉通南、北缘发育2．4～2．0Ga岩浆作用，指示长期处于大陆边缘弧或者岛弧背景，-2．0Ga还发育超高温变质作用。两个古陆都发育～2．0Ca前类似大陆边缘弧特点的岩浆活动，只是圣弗朗西斯科克拉通时代稍早。1．8Ga以来，两个古陆均发育多期岩墙群，部分基本同期，如-1．78Ga岩墙群、-1．7Ga岩墙群和一0．92Ga岩墙群等；不同的是，华北古陆发育约1．3～1．2Ga岩床／墙群，而圣弗朗西斯克拉通发育-1．5Ga岩墙群。1．8-0．8Ga，两个古陆上都断续发育（火山）-沉积建造：1．8—1．6Ga以及1．4—1．2Ga，两者的沉积建造同样以石英砂岩等碎屑岩为主，碳酸盐岩较少；1．2—1．0Ga前，两者的记录均较少，或暂不能确定；1．0—0．8C．a，两者均发育碎屑岩和碳酸盐岩；1．6—1．4Ga，华北古陆发育碳酸盐岩建造，而圣弗朗西斯科克拉通则发育碎屑岩建造。华北古陆新元古界地层中碎屑锆石常显示-1．5Ga的峰值，该期岩浆岩鲜少报道于华北古陆，但却见于圣弗朗西斯科克拉通。两个陆块都发育太古宙-古元古代条带状铁建造铁矿、古元古代石墨矿、中新元古代沉积-喷
Recently, an Early Neoproterozoic North China-Sao Francisco connection model has been proposed; however, it awaits further evidence. In this paper, Precambrian geological records of the two cratons have been summarized and compared, aiming to provide clues to evaluate the above model. Major crustal events peaked at -2.7 Ga in both cratons; however, there were distinct -2.5 Ga crustal growth and reworking events in the North China Craton, which are seemly absent in the S^o Francisco Craton. There are only a few 2.4-2.2 Ga volcanics and plutons in the North China Craton, comparing with widespread rifting-related volcanic- sedimentary formations and plutons at -2.1 Ga and arc-related igneous series and ultra-high temperature metamorphism at -2.0-1.9 Ga, which resulted in the amalgamation of the eastern North China Craton and the western North China Craton to form the unified North China paleocontinent. As for the Sao Francisco Craton, there is a long-lived magmatism event along both the northern and southern margins of the block during 2.4 - 2.0 Ga, including - 2.0 Ga ultra-high temperature metamorphism. It is likely that both cratons have experienced - 2.0 1.9 Ga arc-events except that the peak metamorphism is slightly earlier in the Sao Francisco Craton than that in the North China Craton. There are several generations of 1.8 ~ 0.8 Ga major dyke swarms in both cratons, and some of these are coeval, e.g., - 1.78 Ga, - 1.7 Ga, and - 0.92 Ga dyke swarms; however, there are - 1.3 - 1.2 Ga sills/dyke swarms in the North China Craton but -1.5 Ga dyke swarms in the Sao Francisco Craton. There are 1.8-0.8 Ga （volanic-） sedimentary formations in both cratons： they comprise of quartz-sandstone-dominated clastic rocks with minor carbonates for 1.8- 1.6 Ga and 1.4 -1.2 Ga sequences, and clastic sediments and carbonates for 1.0-0.8 Ga sequences; however few 1.2- 1.0 Ga records or sequence （s） have been confirmed. There is a 1.6-1.4 Ga carbonate-dominated sequence in the North China Craton but a clastic sediments-domi
作者
彭澎
孙风波
王冲
王欣平
苏向东
张志越
周小童
Peng Peng1＇2 Sun Fengbo1＇2 Wang Chong1＇2 Wang Xinping1＇3 Su Xiangdong1＇2 Zhang Zhiyue1,2 Zhou Xiaotong1＇2(1. Procambrlan Geology Group, State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029; 2. School of Earth Sciences, University of Chinese Academy of Sciences, Beifing 100049 3. School of Geographic Sciences, Shanxi Normal University, Linfen, Shanxi 04100)
出处
《地质科学》
CAS
CSCD
北大核心
2018年第2期363-399,共37页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
中组部万人计划资助.
关键词
华北克拉通
圣弗朗西斯科克拉通
前寒武纪
基底
岩墙群
沉积建造
矿产资源
North China Craton, Sao Francisco Craton, Precambrian, Basement, Maficdyke swarms, Sedimentary formations, Mineral deposits
