Abstract: Chemo-stratigraphic analysis will help to solve the problem of the Ordovician-Silurian Boundary, which might locate in the bed of mudstone intercalated with dolostone from the top part of the Lower Member to the basal part of the Middle Member of the Kepingtage formation at the Dawangou Section in the Keping County. Systematically collected seventy two samples were measured by ICP, and data were compared and emended. The w(Ce)/w(La) chemo-stratigraphic analysis indicates that this bed can be subdivided into three chemo-beds. The chemo-fluctuation might reflect the fluctuation of oxidation-deoxidation, and can be correlated with the changes of fossils. The chemo-spike might be corresponding with the anomaly around the boundary of the Ordovician-Silurian at the east Yangtze Gorger.

Key words: chemo_stratigraphy, Silurian, Kepingtage formation, Dawangou, Tarim

摘要： 新疆塔里木盆地奥陶系-志留系界线可能在柯坪县大湾沟剖面柯坪塔格组下段顶部-中段底部的泥岩夹白云岩地层内穿过，化学地层分析将有助于该界线问题的解决。对系统采集的72个样品进行ICP测试和数据对比、校正，w(Ce)/w(La) 化学地层分析结果表明，柯坪塔格组下段-中段界线层可细分为3个化学地层段，化学波动趋势可能反映了古水体氧化-还原度的变化，其与生物化石的变化趋势可对比，出现的异常峰可能与峡东奥陶系-志留系界线附近的异常相对应。

关键词: 化学地层, 志留系, 柯坪塔格组, 大湾沟, 塔里木