Research On Structural Character And Deforming Conditions About Tectonic Schist Of Xiamaling Formation, Southern Of Fangshan Pluton

The studied area, which locate in the middle and upper proterozoic, have under through Archean, Indosinian, Yanshanian and Himalayan tectonic cycles, during the Indosinian tectonic cycle, there was a detachment fault formed between the basement and the cover, together with a EW striking sub-detachment fault which formed at the upper and under side of Xiamaling formation, Qingbaikou group, on the top-wall of the main fault. During the Yanshanian tectonic cycle, as the Fangshan pluton intrusived from SE to NW, the contacting zone under gone replacement and formed tectonic schist, with the newly formed foliation S1 parallel to S0.For the Fangshan pluton and Fangshan metamorphic dome, the tectonic schist of Xiamaling formation must be the ligament of them, so the study of it could be helpful for their correlation. Based on the field observe, micro-investigation, quantitative analysis on the deformation character and deformation mechanism of the tectonic schist, this thesis draw the conclusion as follows: The schist with its schistose S1 parallel to S0 was the result of the thermodynamic metamorphism of magmatic diaper of Fangshan pluton.On the permeative foliation there are directional mineral growth lineation formed, based on the analysis of the conjugate fractures and zonations on the cross section of andalusite, it could be realized that the andalusite, which undergone syntectonic progressive deformation, was the production of Fangshan pluton which intrusived timed.Based on the statistic analysis of the mineral growth lineation, the |ò3 trace on the southern side of the contacting zone of the Fangshan pluton concentrate between 130?? and 160??, based on the statistic analysis of sub-grains and recrystallized grains of quartz, this thesis worked out the difference stress during the pluton intrusion is 75MPa~90MPa.Fluid nclusion decrepitation and garnet-biotite thermometer temperature is about 600??, combining with the unconventionally geothermal gradient(220?? .km-1), thecalculated depth where the dynamic-thermal metamorphism formed was 2.69-3.11km. The time when the schist formed was 133Ma~127Ma based on the relativity of the schist and Fangshan pluton.