西南印度洋洋中脊(SWIR)热液A区的超慢速区岩浆活动的热模拟  

Numerical thermal modeling of the magmatism at ultraslow spreading zone of hydrothermal area A of Southwest Indian Ridge (SWIR)

作　　者：卞龙[1,2] 张健[1,2] 阮爱国 

机构地区：[1]中国科学院计算地球动力学重点实验室,北京100049 [2]中国科学院大学地球科学学院,北京100049 [3]国家海洋局第二海洋研究所,杭州310012 [4]国家海洋局海底科学重点实验室,杭州310012

出　　处：《中国科学院大学学报（中英文）》2016年第6期792-801,共10页Journal of University of Chinese Academy of Sciences

基　　金：国家自然科学基金(41574074;41430319;41174085);中国科学院战略先导项目(XDA1103010102);中国科学院创新团队项目(KZZDEW-TZ-19)资助

摘　　要：中国大洋环球21航次第6航段在西南印度洋洋中脊(SWIR)热液A区获取了OBS地震数据,发现了位于该区第27洋脊段的低速区.基于该低速区地震P波速度模型,用有限单元法开展热模拟计算,研究低速区可能存在的岩浆活动及其热效应.结果表明:1)现今海底热液活动特点支持岩浆房存在底部供热热源的情况.热点供热使岩浆在沿断裂移动过程中产生热异常,形成新的岩浆房,为现今热液活动提供热源.2)随温度变化的热导率对模拟计算结果影响较大.通过反演拟合热导率模型系数,并利用实验室统计结果校正热导率模型,计算出研究区莫霍面温度约为910℃,热点热流约为190 m W·m^(-2).The Chinese DY115 -21 cruse acquired valuable OBS seismic data at hydrothermal area A of SWIR and discovered a low-velocity zone which located on the 27th segment of SWIR. Based on velocity section of P wave, we use the finite element method to model the heating process, aiming to discover the possible magmatism and heat effect of the low-velocity zone. The results are given as follows. 1 ） The current seafloor hydrothermal activity indicates the existence of bottom heating power in the magma chamber. Hotspot causes thermal abnormality in the process of magma moving along the fracture and creates a new magma chamber to provide heat resource for current hydrothermal activities. 2） Temperature-dependent thermal conductivity greatly influenced the results of the thermal modeling. The modeling results show that the moho temperature of the research area is about 910 ℃ and the heat flux at the hotspot is about 190 mW·m^-2.

关 键 词：西南印度洋洋中脊 岩浆房 热模拟 莫霍面温度 热点 

分 类 号：P314[天文地球—固体地球物理学]