【摘要】 思茅中生代红层盆地中央的宁洱和通关两地在第四纪均发生过小规模的玄武岩浆喷发,喷发渣锥至今清晰可见,而同属于该盆地中央的思茅-普洱地震区百年来6级地震密集发生。思茅盆地中央断裂发育,新构造隆升显著,壳幔速度和电性结构意味着该地区现今仍有可能存在着岩浆活动。然而,对宁洱-通关火山区目前到底有无壳内岩浆房和岩浆活动,以及岩浆活动与思普地震带地震活动的关系仍知之甚少。利用该地区的温泉资料和水化学分析数据,我们对宁洱-通关火山区及邻区范围内的36个温泉的热储温度进行了估算,得到了36个点的热储温度数据,通过克里金插值方法获得了宁洱-通关火山区的热储温度空间分布。结果发现:在宁洱火山和通关火山附近存在2个热储温度在220℃以上的温度场高值异常区。综合考虑我们的地热场结果、前人的速度和电性结构等深部探测资料,我们认为:宁洱-通关火山区现今仍存在2个岩浆房,第1个岩浆房位于宁洱县城一带,第2个岩浆房位于墨江通关火山区附近;但宁洱火山和通关火山已不在现今岩浆房的正上方,各反向错开约18km,由此推断把边江断裂(F2)为右旋错动,其中更新世以来的右旋错动速率为18mm/y;宁洱地区频繁而密集的中强地震活动与深部岩浆活动及其产生的深源流体活动密切相关。岩浆的存在使上部地壳与下伏地壳充分解耦并产生应力集中,深源流体活动则有利于断层发生错动。更多还原

【Abstract】 Small-scale eruptions of basaltic magma occurred at both Ning’er and Tongguan in the central Simao Mesozoic Red Strata Basin( SMRSB) in Quaternary,and these eruption cinder cones are still clearly visible at present. In the meanwhile,earthquakes with magnitude 6 frequently occurred in the Simao-Pu’er earthquake zone,which is also in the center of SMRSB,during the last one hundred years. Significant Neotectonism such as faulting and uplifting,the crust and mantle velocity and the electrical structure in central SMRSB mean that magmatism may still exist in this region today. However,whether crustal magma chambers actually exist or not in Ning’er-Tongguan volcanic zone present day and how magmatism interacts with seismicity in Simao-Pu’er seismic zone are still poorly understood. Here,using the pre-existing and our thermal spring chemical composition data,we estimate geothermal reservoir temperatures of 36 springs in Ning’er-Tongguan volcanic zone and adjacent areas,obtaining the spatial distribution pattern of reservoir temperatures in Ning’er-Tongguan volcanic zone by using Kriging Interpolation Method( KIM). Our data show that there exist two anomalous areas where the reservoir temperatures are above 220℃ in the vicinity of Ning’er and Tongguan volcanoes. Combining with deep exploration data such as velocity and electrical structure,our results suggust that there still exist two magma chambers in Ning’erTongguan volcanic zone today. The first magma chamber locates in Ning ’er town,and the second magma chamber locates near Tongguan volcano,Mojiang,but both Ning’er volcano and Tongguan volcano locate no longer above their today’s magma chambers,respectively. These two volcanos drift from their magma chamber about 18 km in the opposite directions,suggesting the Babianjiang fault( F2) is of dextral strike-slip fault,which dextral dislocation rate has been being up to 18mm/y since Middle Pleistocene; The frequent and dense moderate-strong earthquake activity in Ning’er areas is closely related to deep magmatism and magma-derived fluids activities; The presence of magma fully decouples the upper crust from the underlying crust and results in stress concentration,and magma-derived fluids activity is beneficial to faulting.更多还原