黑龙江省东部依兰地区金沟花岗岩的锆石U-Pb定年及其地质意义

ZIRCON U-Pb DATING AND GEOLOGICAL IMPLICATION OF THE JINGOU GRANITE IN YILAN AREA, EASTERN HEILONGJIANG PROVINCE

摘要: 为查明黑龙江岩群的形成时代及其构造背景，对出露于黑龙江省东部依兰地区侵入黑龙江岩群的金沟花岗岩体进行了锆石LA-ICP-MS U-Pb定年研究.结果显示：D2279样品锆石多具有清晰的生长振荡环带，其Th/U比值多在0.1~1之间，属于典型的岩浆成因锆石，获得的²⁰⁶Pb/²³⁸U加权平均年龄为261.18±0.74 Ma（n=20，MSWD=0.66），代表了岩体结晶年龄.金沟花岗岩体形成时代的厘定，不仅限定了黑龙江岩群的形成时代，同时为进一步探讨佳木斯地块晚古生代构造演化提供了新证据.

Abstract: The LA-ICP-MS U-Pb dating is researched for zircon from the Jingou granite in Heilongjiang rock group, which occurs in Yilan area of the Eastern Heilongjiang Province, to identify the formation age and tectonic setting of the Heilongjiang rock group. The results show that the zircon in the sample of D2279 has a clear growth zoning, with Th/U ratios mostly between 0.1 and 1, belonging to typical magmatic zircons. The ²⁰⁶Pb/²³⁸U weighted average age is (261.18±0.74) Ma (n=20, MSWD=0.66), which represents the crystallization age of the rock. The definition of the age of Jingou granite not only defines the forming age of Heilongjiang rock group, but also provides new evidence for further exploration of the Late Paleozoic tectonic evolution of Jiamusi block.