论文部分内容阅读
西藏松多榴辉岩系典型的古洋壳俯冲产物。通过岩相学观察与热力学计算,证实了西藏古洋壳俯冲时经历了还原反应,俯冲洋壳中Fe~(3+)和S~(6+)等物质被还原成Fe~(2+)和S~(2-),在俯冲通道内释放出富含CO_2和H_2S的流体。后者因密度低,从俯冲通道上升至岛弧火山之下的岩浆房中,最终通过火山喷发的方式排放至大气圈。因此认为,深俯冲的印度洋洋壳在地球深部也经历了相似的还原反应,将俯冲洋壳表层的硫酸盐转变为含硫流体,再通过坦博拉火山喷发的方式释放出来。现今洋壳持续俯冲,地球深部的还原反应持续进行,新生成的含硫流体正源源不断地汇聚于岛弧火山之下的岩浆房之中,因此,未来坦博拉式火山爆发是大概率事件。
A typical paleo-oceanic crust subduction product from the Songdo eclogite in Tibet. Through the lithofacies observation and thermodynamic calculation, it is confirmed that the ancient oceanic crust experienced the reduction reaction during the subduction, and the Fe 3+ and S 6+ materials in the subducted oceanic crust are reduced to Fe 2+. And S ~ (2-), the fluids rich in CO_2 and H_2S are released in the subducting channel. Due to its low density, the latter rises from the subducting channel into the magma chamber below the island arc volcano and is eventually discharged to the atmosphere by volcanic eruptions. Therefore, it is considered that the deep-subducted Indian oceanic crust also experienced a similar reduction reaction in deep earth, and converted the sulphate in the subducting oceanic surface to sulfur-bearing fluid and released it through the Tambora volcanic eruption. Nowadays, the oceanic crust continues to subdually and the deep earth reduction reaction continues. The newly generated sulfurous fluid is continuously flowing into the magma chamber under the island arc volcano. Therefore, the future Tombola volcanic eruption is a large probability event .