The Longshan Group And Comparison With Qinling Group In GanSu Tianshui Area

As one of three kinds of rock types, the metamorphic rock is always studied as the emphasis by Petrologist and geologist , and the metamorphic rock in erogenic zone is especially more important.The paper emphasises on the Longshan Rock Group and the Qinling Rock Group in GanSu Tianshui area, where the Qilian orogenic zone and the North Qinling orogenic zone are united, The study of the basement rock series can help to understand the tectonic characteristics . mechanical transition . the orogenetic process and provide the scientific basis for connection and comparison.The paper combinds 1:250,000 Tianshui regional geological survey, and researches the Longshan Rock Group and the Qinling Rock Group with the rock association . the character of petrology.the petrochemistry . original rock recovery . the environment of formation . geochemistry . metamorphism. deformation . time correlation, and on basis of the study, comparison with them.Consider that both of metamorphic basement rock series have the identical following character: 1 .Rock associationThe Longshan Rock Group and the Qinling Rock Group are all composed of felsic gneiss> allitic gneiss^ diopsidite plagioclase granulite and marble, and all kinds of rock have the same character of rockassociation.2 .PetrochemistryTo dedicate that the Longshan Rock Group and the Qinling Rock Group have the same original rock style-terrigenous fragmentary rock series, and verify the tectonical enviroment from the plagioclase amphibolite. Both of them are belong to oceanic island and the continental tholeiite series, have the identical formational tectonic enviroment. 3.GeochemistryThe standardized curve of rare-earth element chondritic meteorite has the same trend, the right inclination, have the obvious negative europium, all these features continousily hold the conclusion that the original rock is the parablastesis, has the later archean feature of sedmentary rock, and the data of microelement dedicte that both of them are near the continental edge tectonic enviroment. 4.MetamorphismMetamorphism based on the petrography,the main metamorphism is jinning-caledon period, and undergo the identical formation history. 5. ChronologyThe data of chronology explanates that both of them are belong to the Proterozoic Era.Conclusion: As the basement rock series, the Longshan rock groupand the Qinling rock group have the very similar above character, although they have the different distribution of location, and conclude that they are the same rock group.