西南次海盆洋壳温度变化对岩石热导率的影响  

INFLUENCE OF OCEANIC TEMPERATURE ON THERMAL CONDUCTIVITY OF ROCKS IN THE SOUTHWEST SUB-BASIN OF SOUTH CHINA SEA

作　　者：孟林[1,2] 张健[3] 张训华[1,2] 温珍河[1,2] 

机构地区：[1]青岛海洋地质研究所,青岛266071 [2]海洋国家实验室海洋矿产资源评价与探测技术功能实验室,青岛266071 [3]中国科学院大学地球科学学院,北京100049

出　　处：《海洋地质与第四纪地质》2016年第2期109-119,共11页Marine Geology & Quaternary Geology

基　　金：国家973课题(2013CB429701);国家自然科学基金项目(41174085)

摘　　要：温度对岩石热导率的影响是一个重要的地热学研究课题。在前人岩石热导率实验的基础上,结合南海西南海次盆地壳实际资料,用数值模拟的方法,对倒数型、直线型和指数型热导率-温度模型系数进行了约束,并对温度对热导率影响条件下莫霍面深度的求解方法以及海底热流与莫霍面温度关系的探讨产生了新的认识。计算结果表明：倒数型（K（T）=a＋b/（T＋c）,a、b、c为常数）和直线型（K（T）=a·T＋b,a、b为常数）热导率-温度模型系数呈线性相关,指数型（K（T）=a·ebT,a、b为常数）则更符合二次多项式形式,据此可简化热导率-温度表达式系数个数,使岩石热导率与温度之间的定量化描述更进一步。根据模拟结果与实验室统计结果对比分析得到西南次海盆莫霍面深度为14~16km。通过热导率-温度模型系数反演发现,热导率受温度影响时海底热流值同莫霍面温度呈正相关,当海底热流为100~125mW/m2、莫霍面深度为10.3km时,西南次海盆莫霍面温度为420~540℃,且随莫霍面深度增加而升高,当莫霍面深度增至14~16km时则可达600~1 000℃。The influence of temperature on thermal conductivity of rocks is an important research topic in earth sciences.On the basis of previous experiments on thermal conductivity of rocks,we further solved nonlinear differential heat conduction equation with numerical methods,and then estimated the coefficients of reciprocal,linear and exponent thermal conductivity-temperature models in this paper.After that,based on the above postulated models and related actual crustal data of the Southwest Sub-basin in the South China Sea,we constrained Moho depths and explored the correlations between seafloor heat flux and Moho temperature using thermal simulation and inversion methods.The results indicate that the coefficients that constituted the reciprocal or linear model were linearly related,while the coefficient relationship in the exponent model was more according to quadratic polynomial fitting form.By that way,we can simplify the model expression and make a further step towards the quantified expression about thermal conductivity and temperature.Through comparing the results of numerical simulation and experimental statistics,we obtained that the crustal thickness of Southwest Sub-basin was 14~16km,and according to the inversion results about model coefficients we drew another conclusion that seafloor heat flux and Moho temperature was positively related when thermal conductivity was influenced by temperature.When seafloor heat flux is 100~125mW/m2 and Moho depth is 10.3km,Moho temperature of Southwest Sub-basin is 420~540 ℃;Moho temperature increases with Moho depth,being as large as 600~1 000℃ when Moho depth increases to 14~16km.

关 键 词：温度 热导率 非线性微分方程 数值模拟 南海西南次海盆 

分 类 号：P736.3[天文地球—海洋地质]