| 华北和圣弗朗西斯科克拉通前寒武纪地质对比 |
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| 引用本文： | 彭,澎,孙风波,王,冲,王欣平苏向东,张志越,周小童.华北和圣弗朗西斯科克拉通前寒武纪地质对比[J].地质科学,2018,0(2):363-399. |
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| 作者姓名： | 彭 澎 孙风波 王 冲 王欣平苏向东 张志越 周小童 |
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| 作者单位： | 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;中国科学院大学地球科学学院 北京 100049;山西师范大学地理科学学院 山西临汾 041004 |
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| 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-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～2.7 Ga前；不同之处是，华北古陆经历了显著的～2.5 Ga前的陆壳生长和改造，而圣弗朗西斯科克拉通则似乎没有。华北古陆2.4～2.2 Ga期间发育少量变质火山-沉积岩系和花岗岩，～2.1 Ga前后广泛发育裂谷火山-沉积建造及侵入岩，2.0～1.9 Ga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2.4～2.0 Ga岩浆作用，指示长期处于大陆边缘弧或者岛弧背景，～2.0 Ga还发育超高温变质作用。两个古陆都发育～2.0 Ga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。1.8 Ga以来，两个古陆均发育多期岩墙群，部分基本同期，如～1.78 Ga岩墙群、～1.7 Ga岩墙群和～0.92 Ga岩墙群等；不同的是，华北古陆发育约1.3～1.2 Ga岩床/墙群，而圣弗朗西斯克拉通发育～1.5 Ga岩墙群。1.8～0.8 Ga，两个古陆上都断续发育（火山）-沉积建造：1.8～1.6 Ga以及1.4～1.2 Ga，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；1.2～1.0 Ga前，两者的记录均较少，或暂不能确定；1.0～0.8 Ga，两者均发育碎屑岩和碳酸盐岩；1.6～1.4 Ga，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～1.5 Ga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-喷流型铅锌矿等。不过，华北古陆发育的古元古代硼矿、菱镁矿，中元古代碳酸岩型稀土矿等在圣弗朗西斯科不发育；而后者发育的绿岩带型相关金矿、镍矿、祖母绿宝石矿等，华北似乎不发育。另外，0.7～0.5 Ga，圣弗朗西斯科克拉通周边广泛发育泛非期造山带，而华北古陆并没有这一事件的明确记录；显生宙，圣弗朗西斯科克拉通相对稳定，中生代与刚果克拉通分离；但华北古陆内部经历强烈的构造-岩浆活动（峰期在中生代）。华北与圣弗朗西斯科克拉通前寒武纪是否相邻还需进一步地质对比和古地磁工作，尤其应关注约2.0～1.9 Ga岩浆-变质（造山）事件、约1.8～1.7 Ga岩浆-沉积（裂谷）事件以及约0.9 Ga岩浆-沉积（裂谷）事件。从地质记录的相似性角度来看，华北东南缘与圣弗朗西斯科南缘的地质记录相似性最大，可延续性最强，最可能相邻。
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| 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 |
| 收稿时间： | 2017-08-10 |
| 修稿时间： | 2017-08-10; |
Comparing the Precambrian geology of the North China Craton and the São Francisco Craton |
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| Peng Peng Sun Fengbo Wang Chong Wang XinpingSu Xiangdong Zhang Zhiyue Zhou Xiaotong.Comparing the Precambrian geology of the North China Craton and the São Francisco Craton[J].Chinese Journal of Geology,2018,0(2):363-399. |
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| Authors: | Peng Peng Sun Fengbo Wang Chong Wang XinpingSu Xiangdong Zhang Zhiyue Zhou Xiaotong |
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| Institution: | Precambrian Geology Group, State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029;School of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049;School of Geographic Sciences, Shanxi Normal University, Linfen, Shanxi 041004 |
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| Abstract: | Recently, an Early Neoproterozoic North China-São 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 São 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 São 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 São 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 São 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-dominated suite in the São Francisco Craton. It needs to be mentioned that there are plenty of ～1.5 Ga detrital zircons in the Neoproterozoic strata in the North China Craton, of which rare coeval igneous rocks have been reported, comparing with a distinct igneous event peak in the São Francisco Craton. Both cratons developed Archean-Paleoproteorzoic banded iron formation-related iron deposits, Paleoproterozoic graphite ore deposits, and Meso-Neoproterozoic volcanic-sediments-related sulphide lead-zinc ore deposits. Paleoproteroizc boron and magnesite deposits, and Mesoproterozoic carbonatite-related rare earth element ore deposits were developed in the North China Craton, but not in the São Francisco Craton; on the other hand, greenstone belt-type gold and nickel deposits, as well as emerald gem deposits are important in the São Francisco Craton but not in the North China Craton. During ～0.7～0.5 Ga, the São Francisco Craton was surrounded by the Pan-Africa orogenic; whereas it seems absent in the North China Craton. During Phanerozoic, the São Francisco Craton was stable, except that its broke away from the Congo Craton during the Mesozoic; while the North China Craton has experienced strong tectno-magmatic event during Mesozoic. More work based on detailed geological comparison and paleo-magnetic poles is needed to confirm their neighbourhood, focusing especially on the ～2.0～1.9 Ga igneous-metamoprhic（orogenic）event, the ～1.8～1.7 Ga igneous-sedimentation（rifting）event, and the ～0.9 Ga igneous-sedimentation（rifting）event. Nevertheless, if the two blocks were neighbours, the eastsouthern margin of the North China Craton and the southern margin of the São Francisco Craton are possible linking positions for their similar and continous geology. |
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| Keywords: | North China Craton São Francisco Craton Precambrian Basement Mafic dyke swarms Sedimentary formations Mineral deposits |
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