华北陆块基底构造格局及早期大陆克拉通化过程

Tectonic framework of North China Block and its cratonization in the early Precambrian.

依据区域构造分析及同位素年代学数据库 ,华北克拉通变质基底主要可以区划为以下构造单元 :1)鄂尔多斯陆块新太古代被动边缘沉积 ;2 )恒山 -承德太古代末期构造带 ;3)太古代末期五台 -登封岛弧带杂岩及构造缝合带 ;4)鲁西 -冀东 -辽吉新太古代活动大陆边缘岩浆杂岩带 ;5 )胶辽陆块 ;6 )冀北 -固阳古元古代初造山带及内蒙 -冀东再造麻粒岩相带 ;7)吕梁 -中条古元古代裂谷带 ;8)辽南古元古代裂谷带。华北克拉通早期构造演化历史主要涉及东部陆块西缘的岛弧增生及其与西部陆块的碰撞拼合 ,太古代末期克拉通北缘开始形成增生型陆缘活动带 ,并造成克拉通中部的裂谷作用。东部古郯庐断裂带的活动造成辽南 -鲁北古元古代裂谷带的形成。最后 ,以古元古代末期的拗拉谷系、基性岩墙群为标志的伸展构造体制 。

The tectonic division of North China Block(NCB) basement and its evolution in early Precambrian is an important issue, as many efforts are concentrated in its petrology, metamorphic geology and isotopic chronology. Recently, many new evidences are revealed, which bring new light to its tectonic evolution in early Precambrian. Based upon preliminary tectonic analysis and isotopic age database, we subdivide NCB's basement into following unites from west to east: 1) Ordos Neoarchean khondalites associated with passive continental margin(2.50Ga); 2) Hengshan Chengde Neoarchean high pressure granulite bearing tectonic belt(2.50~2.45Ga); 3) Wutai Dengfeng island arc complex and suture zone( 2.50Ga ); 4) Taihang Neoarchean accretionary prism(2.60Ga); 5) West Shandong island arc TTG complex greenstone belts(2.70~2.60Ga); and 6) Liaoning Mesoarchean relic blocks(>2.70Ga). Furthermore, Lliang Zhongtiao rifting genetic supracrustal belts (2.50~2.30Ga) are superimposed upon the central portion of NCB, and a huge granulite facies province(GFP) occurs along its northern margin associated with south directed subduction accretion and reworking in the Palaeoproterozoic (2.50~2.40Ga). With plate tectonic model, the tectonic evolution of NCB from Neoarchean to early Palaeproterozoic could be well interpreted; its cratonization involves at least three periods of accretion or collision. At first, West Shandong island arc was formed along the western margin of Liaoning Block in the Neoarchean. Lately, Ordos passive margin subducted to the east in Neoarchean, leading to generation of Wutai island arc and collision of Ordos with Wutai. Finally, subduction belt jumped to the northern margin of NCB resulted in the opening of Lliang Zhongtiao rift in its central portion, and formation of GFP along its northern margin (2.50~2.40Ga). The closure of Lliang Zhongtiao rift is associated with the long distance intra plate orogeny in the Palaeoproterozoic (2.30Ga), marking the finial cratonization of NCB.