中子活化技术在层序地层学中的应用

中子活化分析是一种重要的核分析技术，具有灵敏度好、精密度和准确度高、多元素分析、免除试剂的空白、基体效应小、不损坏样品等优点，在地学研究领域具有广阔的应用前景。笔者将它应用于层序地层学的研究中。通过对地层中宇宙化学特征元素（如Ｃｏ，Ｉｒ等）及ＲＥＥ元素丰度值的测定，建立了一套计算海相地层的沉积速率、相对海平面变化、间断面的精细时间结构的定量计算方法，并成功地运用于贵州紫云海相地层的层序地层学研究，恢复了该地区晚二叠世具线性时标的相对海平面变化定量曲线。

APPLICATIONS OF NEUTRON ACTIVATION ANALYSIS IN SEQUENCE STRATIGRAPHY

The neutron activation analysis is a kind of technique with high sensitivity, good accuracy, multi elemental analysis and non destruction of samples etc. Based on the applications of this technique in sequence stratigraphy, a series of new concepts about the chemical sequence stratigraphy including the condensation surface, missing time record etc. have been defined. Using the Co and La abundance examined with INAA, we can calculate the true sedimentation rates of the sediment samples, and the missing time scales of the condensation surfaces such as the subaqueous hard bottom surfaces and the weathering crust surfaces, then get the sample's absolute water depth further by using the water depth formula introduced in this paper. On the base of that all the missing time records at the erosional and hiatus surfaces are considered in the calculation of the time coordinates, we can understand quantitatively the sea level eustasy with time. This method has been used successfully on the sequence stratigraphic study of a section of Permmian carbonate in Ziyun, Guizhou, China.