A Comparative Study On The Diagenetic And Metallogenic Depths Of The Antuoling, Gangzidonggou Deposits In Hebei Province And Bainaimiao Deposit In Inner Mongolia

The deposits of Antuoling, Gangzidonggou and Bainaimiao are lying in thedifferent position of the north China platform. They have different types of ores andminerals. Many scholars have paid their attention to them for their rich types. Basedon these studies, this article is focused on the study of the diagenetic and metallogenicdepths, and compare the applicability of the different geobarometers, which to theaccurate diagenetic and metallogenic depths. These results will be reached to providetheoretical foundation to deep prospecting and deep prediction.Through the systematically research of these3deposits, their diagenetic andmetallogenic depths are calculated by using granite geobarometer, biotitegeobarometer and fluid inclusion geobarometer respectively. After compare andanalyse these results, the conclusions as followed:(1) The depths by using granite geobarometer are more shallow than the depthswhich are calculated by using biotite geobarometer. Moreover, as a result of the datais according to CIPW theoretical formula, the depths may be deviation from the actualsituation. Thus, these results are only counted as semi-quantitative ones.(2) Before using geobarometer, we must pay attention to the different conditions.For example, the hornblende geobarometer is more suitable for calculating the depthsof the calcic-alkalic granite, and the suitable range is2.0—13kbar; the biotitegeobarometer is more suitable for calculating the depths less than2.0kbar.(3) The system info of fluid inclusion geobarometer is more advanced and moreaccurate than others. Because of the fluid inclusion is sensitive to pressure, fluidinclusion’s temperature-measuring and calcutation will be changed by the structuraldeformation in post-oreperiod. So, through the petrographical and statistics analysis,the proper pressure could be determined in the consideration of actual geologicalcondition.(4) With the help of granite geobarometer, the diagenetic pressures of rock bodyin Antuoling, Gangzidonggou and Bainaimiao deposits are119—167MPa,43—140MPa and84—151MPa; the metallogenic pressures which are calculated byusing biotite geobarometer are116.3—160.3MPa,32.4—128.1MPa,103.8—133.5MPa; the forming pressures of Gangzidonggou and Bainaimiao depositswhich are calculated by fluid inclusion geobarometer are50—125MPa and 100—150MPa. By the consideration of lithostatic pressure and pressure gradient of27MPa/km, the diagenetic depths of these3deposits are4—6km,1—5km,3—6kmand the metallogenic depths are4—6km,1—5km,3—5km.