摘要
以地震测深剖面提供的地壳结构为初始模型,结合大陆科学钻探岩芯和地表地质资料,对苏鲁地区40000 km2的1∶10万航磁资料进行了处理。根据岩石磁性参量与岩性的相互关系,对该区3条断面进行了约束反演计算,获得了3条断面的岩层结构特征:5 km深度范围内主要为榴辉岩、大理岩和片麻岩,5~7 km为含柯石英榴辉岩的超高压变质岩片,7 km至上地壳底部为经历超高压变质的片麻岩或花岗闪长岩;中地壳(10~19 km)主要为高压变质片麻岩和后期侵入的花岗岩,下地壳(>19 km)主要为酸性、基性麻粒岩。3条剖面上的超高压变质岩片向北倾斜至地表,说明它很可能是华北克拉通的俯冲和原路折返的结果。
The areomagnetic data of the 1∶100 000 from JiangsuShandong orogenic belt are processed based on the primary model of the earth crust structure provided by the deep seismic reflection and other geophysical investigations with magnetism of the core petrology at the CCSD pilot-hole.According to the relationship between the magnetic parameters of the rocks and lithology,restraint inversion is carried out for three sections.Based on the magnetic features of the three sections and deep seismic feflection data,the terrane structure characteristics are given.Pofile I,46 km long,starts from Dazhai of Zhucheng to Boerzhen of Jiaonan;profile II,80 km,from Bahu of Linyi City to Hushan,Rizhao City;and Profile Ⅲ,139 km long,from Tancheng,Shandong to Lianshui,Jiangsu.The inversion results show that the area within a depth of 5 km is dominated by eclotite,marble and gneiss.While inversed magnetic bodies,5 and 7 kilometers deep below the surface,are mainly the UHPM rock slices containing mainly coesite-bearing eclogite.The strata from 7 km to the bottom of upper crust mainly consist of gneiss,granite and granite diorite that have undergone ultra high pressure metamorphic process.Middle crust(10—19 km) is mostly composed of UHPM gneiss and granite of later intrusion.The lower crust contains acid and basic granulite.The northward dipping to the surface of the three profiles reveals that they may have been resulted from the subduction of North China craton and returned along the original path in Triassic period.