江苏东海超高压榴辉岩的热导率及对大陆科学钻探研究的意义

欧新功; 金振民; 金淑燕; 徐海军

江苏东海超高压榴辉岩的热导率及对大陆科学钻探研究的意义

中国地质大学地球科学学院, 湖北武汉 430074

基金项目: 国家“九五”重大科学工程中国大陆科学钻探工程项目资助

详细信息

作者简介:
欧新功(1974-), 男, 中国地质大学在读博士生, 主要研究方向为岩石物理性质及大陆深部构造. E-mail: xgou@cug.edu.cn

中图分类号: P54;P62
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出版历程
- 收稿日期: 2003-01-17
- 刊出日期: 2003-03-25

Thermal Conductivity of Donghai UHP Eclogite and Its Significance for Studying Continental Scientific Drilling

Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China

摘要

摘要: 对采自江苏东海毛北地区(中国大陆科学钻探先导孔附近) 的新鲜榴辉岩样品进行了岩石热导率的测定, 初步查明了该区榴辉岩热导率随矿物组成的变化关系, 探讨了岩石结构特征和温度变化对热导率的影响.本次所测东海超高压榴辉岩的热导率介于3.2 2 2~ 3.716Wm^-1·K^-1之间并随岩石中2种主要矿物的相对含量比而变化, 随着榴辉岩中石榴石对绿辉石体积比(V_Grt/V_Omp) 的增加而降低, 近似的函数关系满足K =3.76 7- 0.18× (V_Grt/V_Omp).岩石中矿物分布的不均匀性和面状构造的发育对榴辉岩热导率的影响较大, 由此产生的热导率各向异性可达近10 %.温度是影响热导率的另外一个重要因素.结合本次的实测资料和相应的热导率-温度关系, 建立了东海地区榴辉岩热导率随温度的变化关系方程K (T) =1/ (7.85×10^-2 +6.95×10^-4 ×T), 根据这一方程并结合东海地区的地热梯度资料推算了榴辉岩热导率随5 0 0 0m钻孔深度的变化关系, 推测东海地区科学钻探施工至5 0 0 0m深度时, 榴辉岩的热导率将比地表平均降低2 4%.该成果为钻探测井资料的解释以及该区地热结构模型的建立提供了重要依据和约束资料.
- 超高压榴辉岩 /
- 热导率 /
- 稳态半环型热导仪 /
- 大陆科学钻探 /
- 江苏东海
Abstract: UHP eclogite samples were collected from surface exposures around Chinese Continental Scientific Drilling (CCSD) drill-site in Donghai area have been measured on thermal conductivity to investigate the effect of mineral components and texture on thermal conductivity (TC) of eclogite. Measured thermal conductivities vary from 3.222 to 3.716 Wm^-1·K^-1 with average value 3.511 Wm^-1·K^-1, which depend on the volume ratio of garnet and omphacite (V_Grt/V_Omp) in the rocks. This correlation was fitted to the function K=3.767-0.18× (V_Grt/V_Omp), which shows the thermal conductivity of eclogite in this area decreased as increasing of V_Grt/V_Omp. Inhomogeneous distribution of minerals and the foliation texture in rocks also significantly affect the value of thermal conductivity and induce the anisotropy up to 10% in eclogite. For temperature dependence, according to calculations from the correlation between K-T, thermal conductivities under high temperature were also fitted to a function: K (T) =1/ (7.85×10^-2+6.95×10^-4×T), T is absolute temperature. Based on this function and the published geothermal data of this area, a depth dependence of thermal conductivity can be concluded. The K of eclogite decreased as the increasing depth of CCSD drill hole. The K values of eclogite in surface and in bottom of hole are 3.511 Wm^-1·K^-1 and 2.687 Wm^-1·K^-1, respectively. The K of eclogite will be predicted to be decreased about 24% from surface to the end of 5 000 m depth of CCSD. These research results are helpful to establish the geothermal model of this area and to interpret well logging results from CCSD.
- UHP eclogite /
- thermal conductivity /
- half-space line TC meter /
- CCSD /
- Jiangsu Donghai

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图 1 TK04半环型热导率测定仪结构简图

Fig. 1. Configuration sketch of TK04 half-space line thermal conductivity meter

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图 2 东海榴辉岩(01MB24) 热导率测试的加温曲线

Fig. 2. A heating-curve of measured thermal conductivity of eclogite (No.01MB24) from Donghai area

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图 3 单个测量数据(01MB24-01) 的热导率计算及SAM数据评估图解

Fig. 3. Diagrams of thermal conductivity calculating on single measurement (No. 01MB24-01) and SAM evaluation method

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图 4 榴辉岩热导率与矿物组成之间的关系

Fig. 4. Correlation between thermal conductivity and component of eclogite

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图 5 结构不均一性导致的榴辉岩热导率各向异性

Fig. 5. Anisotropy of thermal conductivity associated with inhomogeneous texture of eclogite

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图 6 推算的超高压榴辉岩热导率随CCSD钻孔深度的变化关系

Fig. 6. Correlation between calculated thermal conductivity of UHP-eclogite and depth of CCSD deep hole

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表 1 实验样品的矿物组成和结构特征

Table 1. Mineralogical components and texture of starting material in experiments

表 2 利用矿物成分推算的热导率与实测值的对比

Table 2. Comparison between measured value and calculated thermal conductivity from mineralogical components

表 3 利用热导率-温度关系推测的高温下的热导率

Table 3. Thermal conductivity under high temperature inferred from published correlation of K-T (Wm^-1·K^-1)

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