黑龙江嘉荫地区白垩系与古近系界线附近的古气候分析

Analysis on Palaeoclimate neighbouring the Cretaceous and Paleogene boundary in Jiayin area, Heilongjiang Province

本文在前人应用古生物及锆石测年资料确定的黑龙江嘉荫地区白垩系与古近系界线附近,用地球化学指标分析了该区在该时段的气候变化趋势。作者主要是应用电感耦合等离子发射光谱仪(ICP-AES)测定了界线附近全岩样品的部分元素含量,从中提取能指示气候变化的常规气候指标CaO/MgO、Sr/Ba,并用因子分析的方法综合探讨该区在界线附近的古气候变化。分析结果显示,嘉荫地区在白垩纪末到古近纪初,气候整体上呈气温下降、降水增多的趋势,这一趋势与前人在该区从古生物方面得出的结果以及当时的生态相似区(北美)的气候变化基本一致。

By using geochemical indexes, climatic change tendency was analyzed during the Cretaceous-Paleogene period neighbouring the Cretaceous and Paleogene boundary in Jiayin area, Heilongjiang Province, which was determined by paleontologic materials and zircon-dating data by preresearchers. First, the contents of some major and trace elements in the bulk samples of Baishantou section, a typical outcrop neighbouring the Cretaceous-Paleogene boundary, were determined with Inductively Coupled Plasma-Atomic Emission Spectrometry （ICP-AES）. Then, ratios of CaO/MgO, Sr/Ba and Factor Analysis method were utilized to analyze the climatic change at that time in that area. The results reveal that the descent of temperature and the increase of precipitation were the main climatic characteristics in this area during the Late Cretaceous to Early Paleogene. This conclusion is consistent with other study results by different means （such as paleontology analysis）in this area and with some studies on the palaeoclimatic change in the similar ecology area （the North America）in environment.