Ages of rocks and minerals from the Okhotsk-Chukotka volcanic belt

Current geochronological data on the Okhotsk-Chukotka volcanic belt (OCVB) and relevant problems are discussed. The belt evolution is suggested to be modeled based on 40Ar/39Ar and U-Pb dates more useful in several aspects than common K-Ar or Rb-Sr dates and methods of paleobotanical correlation. Based on new40Ar/39Ar and U-Pb dates obtained for volcanic rocks in the OCVB northern part, the younger (Coniacian) age is established for lower stratigraphic units in the Central Chukotka segment of the belt, and eastward migration of volcanic activity is shown for terminal stages of this structure evolution.

本文讨论了鄂霍次克-楚科奇火山岩带（Okhotsk-Chukotka Volcanic Belt, OCVB）的现有年代学数据及其相关科学问题。研究提出，基于40Ar/39Ar与铀-铅（U-Pb）测年数据对该火山岩带的演化进行建模，此类测年手段在诸多方面优于常规的钾-氩（K-Ar）、铷-锶（Rb-Sr）测年法以及古植物地层对比方法。依托针对鄂霍次克-楚科奇火山岩带北部火山岩获取的新40Ar/39Ar与U-Pb测年数据，研究确定了该带楚科奇中部段内地层下部单元的形成时代为更年轻的康尼亚克期，并揭示了该构造演化末期阶段火山活动向东迁移的特征。