吉南太古宙地体钾事件成因研究

Origin of potassium events on Archean terrain from southern Jilin, China

吉林南部的通化、柳河和白山地区的太古宙表秃岩系和TTG杂岩中，广泛存在钾化、钾长石石英脉和钾质伟晶岩脉，显示在地质历史时期中该区曾经发生过广泛的钾事件。经野外地质调查、显微镜观察以及电子探针、X-射线衍射及稳定同位素综合分析，确定出：①不同产状的钾长石的主要氧化物含量稳定；②从变黑云钾长花岗岩、黑云长英片麻岩到花岗伟晶岩脉，钾长石三斜度和有序度略显增高，但变化幅度较小；③不同产状钾长石的护δ^18O值较集中，变化于（4.90～8.49）×10^-3。认为，该区的钾长石是来自于同一个岩浆源的物质在同一岩浆作用过程中不同阶段、不同就位方式的产物。

Potash replacement, potash veins, potash-quartz veins and kah-pegmatite are widely distributed in Tonghua, Liuhe and Baishan area, southern Jilin Province. It suggests that potassium events ever occurred in the area during the geological time. By field investigation, microscope observation, compositional analysis by EPMA, X-rays diffraction analysis as well as oxygen isotope analysis of potash, it is clear that the compositions of potash in different occurrences are stable; from metamorphic biotite-potash granite to biotite-felsic gneiss and to granite-pegmatite, the anorthic degree of potash increases slightly; and theδ^18O is also stable in value from 4.90×10^-3 to 8.49×10^-3. It shows that the potassium feldspars in the studied area were from the same magma source but occurred in different stages and processes.