doi:10.16186/j.cnki.1673-9787.2020.4.6

Received:2019/11/26

Revised:2020/01/20

Published:2020/07/15

Petrogeochemical characteristics and geological genesis of Zhangshiying rockmass in southern margin of North China block

JIANG Yuping1,2, ZHANG Sensen3

1.Henan Nonferrous Mineral Exploration Engineering Research Center， Zhengzhou  450000 ， Henan， China;2.No. 6 Geological Team of Henan Province Nonferrous Metals Geological Mineral Resources Bureau， Zhengzhou  450000，Henan， China;3.Henan General Institute ofNon-ferrous Metals Geological Exploration，Zhengzhou  450000，Henan，China

Abstract:Based on the study of geochemical characteristics of Zhangshiying rock mass， the genesis and geological significance of the rock mass were discussed. Studies of principal elements presented that granite porphyry ，hornblende quartz syenite and dark inclusions all showed the characteristics of alkaline rocks； trace elements feature showed that the hornblende syenite and dark inclusions in Zhangshiying rock mass had similar distribution pattern curves of rare earth elements， and had high amounts of rare earths， and the curve generally inclined to the right. Both of them had higher total amount of rare earth， the average value of the former was 319.28 × 10^-6 ，δEu =0.24 ~0.25 ，and that of the latter was 357. 00 × 10^-6， δEu =0. 24 ~0. 31 ， the average value of total amount of rare earths of granite porphyry in Zhangshiying rock mass was 156. 63 × 10^-6 ，δEu = 0. 12 ~0. 19. The three types of rocks showed negative anomaly of Eu and positive anomaly of Ce. The trace elements cobweb map of hornblende quartz syenite was similar to that of dark inclusions， which was rich in Rb， Th and other large ion lithophile elements， deficient in Nb， Ta and other high field strength elements， suggesting that the diagenesis was dominated by mantle source material. Granite porphyry has a low w（Nb）/w（Ta） ratio， and the formation process may have the addition of shell source material. To sum up， the Zhangshiying rock mass is a kind of shell-source granite porphyry， which was formed during the transition of tectonic system to the extension， and the subsequent large-scale extension and thinning of the lithosphere.

Key words:southern margin of the North China block;geochemical characteritic;trace element characteristic;Zhangshiying rock mass

华北陆块南缘张士英岩体岩石地球化学特征及地质意义_姜玉平.pdf