摘要
华北克拉通古生代的大地构造演化始于大约520 Ma,此时冈瓦纳古陆的聚合正处于峰期。中寒武世华北克拉通古生代最早的沉积记录始于其边缘的更老地层或者变质基底之上。随后,海相环境扩展,广泛的海侵导致中寒武世晚期馒头组及其上的地层广泛分布于华北克拉通。华北克拉通北部以北的白乃庙岛弧带新的研究结果显示这一岛弧始于520 Ma,并延续到420 Ma,其可以向东延伸到我国东北的四平以东。沿着华北克拉通南部边缘,商丹洋在514~420 Ma期间发生向北的俯冲。华北克拉通的大部分地区在中奥陶世马家沟期发生海退。近10年来在华北克拉通北缘识别出一个又一个泥盆纪深成岩体和火山岩。石炭纪晚期开始的新的沉积层序以"G层"铝土矿为底,其平行不整合,或假整合在中奥陶世马家沟组灰岩之上。铝土矿很可能是从内蒙古古隆起,一个深位剥蚀的岩浆弧,曾经发育的火山喷发活动形成的广布的火山灰转变而来。这进一步说明晚古生代华北克拉通北缘曾经是一个安第斯型活动大陆边缘。这一沉积序列以碎屑岩为主,下部夹海相灰岩和火山灰层,表明其形成于海陆过渡的火山弧环境。二叠纪早期之后华北克拉通的沉积环境转变为陆相。华南地块与南秦岭地块和华北克拉通之间的勉略洋在晚古生代持续向北俯冲增生,三叠纪晚期发生碰撞,导致大别—苏鲁超高压变质带的形成。与此同时,在华北克拉通北部显著的构造变形和岩浆作用发生在三叠纪晚期。燕山地区盘山等地三叠纪晚期的强烈褶皱、冲断发生在约210 Ma,与华北克拉通周缘的强烈构造变形同期。这也暗示华北克拉通此时已经开始失去克拉通的稳定构造性质。
The Early Paleozoic tectonic stage of the North China Craton(NCC)began around520Ma,when Gondwana assembled in its peak tectonism.The Middle Cambrian deposition occurred on older strata or basement rocks along margins of the NCC.Then the marine environment expansion and its extensive invasion led to the late Middle Cambrian marine deposition,with the Mantou Formation and afterward strata distributed throughout the NCC.New research results of the Bainaimiao arc belt to the north of northern NCC indicate that the arc was active from520Ma and lasted until420Ma,which could extend to east Siping in Northeast China.Along the southern edge of the NCC the northward subduction of the Shangdan Ocean took place during ca.514-420Ma.Marine regression occurred later than the Majiagou phase in Middle Ordovician in most parts of the NCC.Recently some Devonian plutons and volcanic rocks were recognized in northern NCC.The Late Carboniferous sedimentary sequence with the'G'layer of bauxites at its bottom overlies the Middle Ordovician limestone in unconformity.The bauxites were derived mainly from ashes produced by volcanism mainly in the Inner Mongolia Paleo-uplift during Paleozoic period,particularly in latest Early Carboniferous to Early Permian when the northern margin of the NCC evolved as an Andean-style active continental margin.The sequence is mainly clastic formations composed of coal-bearing sandstones and siltstones interlayered with marine limestone and volcanic ash,which demonstrates that they formed in a terrestrial-marine transitional or terrestrial environment with volcanic arc settings.After late Early Permian a terrestrial environment was dominant in the NCC.In southern NCC and the Qinling Orogenic Belt spreading of the Mianlue Ocean between the South China Craton and the South Qinling Block was sustained in Late Paleozoic,and the northward subduction-accretion of the Mianlue Ocean was active in Late Paleozoic.In Triassic the collision between the South China Craton and the South Qinling Block along the Mianlue su
作者
赵越
翟明国
陈虹
张拴宏
ZHAO Yue;ZHAI Mingguo;CHEN Hong;ZHANG Shuanhong(Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China;Key Laboratory of Paleomagnetism and Tectonic Reconstruction, Ministry of Land and Resources, Beijing 100081, China;Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China)
出处
《中国地质》
CAS
CSCD
北大核心
2017年第1期44-60,共17页
Geology in China
基金
科技部973课题(2012CB416604)资助~~
