碳酸盐(U-Th)/He同位素定年研究进展与展望  

RESEARCH PROGRESS AND APPLICATION OF CARBONATE U-TH/HE ISOTOPE DATING

作　　者：李一闪 刘红[1] 孙凤霞[1] 刘雷[1] LI Yi-shan;LIU Hong;SUN Feng-xia;LIU Lei(Institute of Earthquake Forecasting,China Earthquake Administration,100036 Beijing,China)

机构地区：[1]中国地震局地震预测研究所,地震预测短临研究室,北京100036

出　　处：《地震地质》2024年第3期723-738,共16页Seismology and Geology

基　　金：国家自然科学基金(42174115)资助。

摘　　要：近年来,碳酸盐(U-Th)/He同位素定年技术在地质学领域中引起了广泛关注。该技术以激光原位(U-Th)/He同位素定年为代表,具有高精度、非破坏性等优点,在测量年龄方面取得了重大突破。由于样品中He含量低、U、Th含量少,导致实验需要相对较大的样品,同时需要使用真空炉、质谱仪等先进设备。针对这些要求,新的(U-Th)/He测年仪也在不断开发。同时,该技术在古地磁学、沉积学、构造地质学等领域中的应用也得到了广泛的探索。碳酸盐(U-Th)/He同位素定年技术具有广阔的应用前景和研究价值,其在解决地球科学问题中将发挥重要作用。文中综述了最近20年以来碳酸盐(U-Th)/He方法和技术的进展,对影响He定年的不确定性因素进行了分析,并对未来的发展方向进行了展望。U-series dating(Uranium series disequilibrium dating)is one of the most widely used dating methods in radioisotope geochronology,mainly based on the disequilibrium relationship between radionuclide 238 U and its decay daughters 235 U/234 U and 230 Th to measure the age of rocks,minerals,and other geological bodies.U-Th/He isotope dating is based on the decay of radioactive elements such as U and Th in mineral particles to form stable 4He isotopes.By measuring the cumulative content of these radioactive element decay products,The U-Th/He dating method has a large applicable time range for many minerals(such as apatite and zircon)and most geological periods,and can be used as a thermal timer to explain the thermal history of rocks,and can also be used as a geological timer to constrain the crystallization age of minerals and different geological events.Carbonate minerals,including calcite,dolomite,magnesite and aragonite,are widely distributed in the earth s crust and formed in the processes of sedimentation,magma,metamorphism and hydrothermal fluid metasomatism.In recent years,with the development of closing temperature theory,the recognition of He diffusion behavior,and new progress in He measurement technique,it has been found that helium can be retained in the lattice of carbonate minerals,and the diffusion activation energy and low closure temperature are close to those of apatite.Carbonate U-Th/He isotope dating technology has been greatly developed and applied in the fields of geochronology and thermochronology,which attracted wide attention in the field of geology.Due to the large particle size and extremely low closure temperature,the application of low-temperature dating of carbonate minerals has received increasing attention.Ideally,a mineral crystal dating with U-TH/He should contain all helium from the decay of the U and Th radioisotopes inside the mineral,that is,there is no inheritance of previously existing helium,and there is no loss of helium after.Any factor that breaks the closure of the U-Th/He

关 键 词：同位素定年 碳酸盐 氦的扩散 

分 类 号：P597[天文地球—地球化学]