Magnetic Structure of the Dengfeng-Lushan Crustal Cross-Section,Henan
摘要
Magnetic parameters for rocks from a crustal cross-section exposed in the Dengfeng- Lushan area,Henan Province are systematically determined.The results,along with their mineralogy, chemical composition,density and P-wave velocity,indicate that there is a general increase in susceptibility K,natural remanent magnetization J.and saturation isothermal remanence J_r with increasing metamorphic grade (apparent crustal depth) from the Early Proterozoic Angou Group (greenschist facies) through the Late Archean Dengfeng Group (amphibolite facies) to the Taihua Group (high-amphibolite to granulite facies).Metasedimentary rocks of the Angou and Dengfeng Groups show a clear paramagnetic nature,while other rock types are dominantly ferrimagnetism.The Taihua Group reflects the magnetic distribution of the lower crust of the cross-section and has average K,J_n and J_r values of 6680×10~(-6) SI,0.166 A/m and 71.78 A/m,respectively,which are in good agreement with those of other exposed high-grade metamorphic ter- rains in the world.