华北陆块区渤海陆块山东部分的厘定及其地质意义

笔者以已完成的山东省1∶5万、1∶20万和1∶25万区域地质资料为基础,运用大地构造相分析方法,鉴别、厘定和划分大陆形成演化过程,编制完成1∶50万山东省大地构造相图。编图研究发现:鲁东和鲁西地区在地层建造特征、岩浆活动、构造环境和成矿作用等方面均存在较大差异,故将原划分的胶辽陆块进行解体,划为鲁西陆块和渤海陆块,并对新划分的渤海陆块进行了定义。渤海陆块是华北陆块区新划出的一个二级构造单元,它的分布范围是指夹持于郯庐断裂带以东、苏鲁-大别高压-超高压带以北的地区,地理轮廓呈狭长的三角形。渤海陆块有自己独特的演化历史,从最初的陆核到汇聚增生,大致经历了前新太古代陆核形成、新太古代大陆地壳快速增生和古元古代大陆被动陆缘和前渊盆地形成和最终汇聚期,与华北陆块的克拉通化同步。渤海陆块的厘定,代表了古老大陆地壳的板块运动的早期表现形式,多由弧火山岩沉积(表壳岩)和TTG岩石组合成为古陆壳的主体,并经历古元古代裂谷盆地发育期,最终拼合期和隆升、剥蚀期的演化过程。

Subdivision of the Bohai Landmass from the North China Block and Its Implications

Based on the data obtained from 1:50 000, 1:200 000 and 1:250 000 regional geological survey and combining with the tectonic facies analysis methods, the tectonic facies map of Shandong was proposed. In this process, we found eastern Shandong was different from western Shandong in strata, magmatism, structural set-ting and mineralization. Accordingly, this work divided the Jiaoliao landmass into twoparts: western Shandong landmass and Bohai landmass. As one of the sub-tectonic units of North China Block, Bohai landmass is a trian-gle-shaped area to the east of Tanlu Fault zones, south of the Sulu-Dabie high-pressure and ultrahigh-pressure metamorphic belt and north of the Xingmeng orogenic system. Bohai landmass has its unique evolutionary histor-ical perspective. It experienced mainly four stages of tectonic evolution:①the formation of the continental nucle-us in the early Neoarchean,②the crustal accretion in the Neoarchean,③the formation of passive margin and fore-deep basin in the Paleoproterozoic and④the final completely conjoined, synchronize with North China Craton. Bohai landmass might have been formed from ancient continental crust (supracrustal rock-TTG rock series), and experienced extensive complex rift basins, collision orogenic, uplift and denudation processes.