论文部分内容阅读
白垩纪是距今最近的“温室地球”时期,研究其气候演变对认识现今气候环境格局形成及演变具有重要意义。通过对六盘山地区下白垩统六盘山群李洼峡组中段红色、绿色泥岩的元素地球化学特征研究,发现2种泥岩中大部分元素变异趋势相似;化学风化指数(CIA)相当(红色泥岩平均为66.3%,绿色泥岩平均为65.5%),反映中—低化学风化强度;A-CN-K图解显示源岩单一。利用CaCO3质量百分含量,(CaO+Na2O+K2O)/Al2O3,TFeO/Mn,Ti/Sr,Rb/Sr,Sr/Ba比值等指标分析显示泥岩颜色差异与气候背景有关,红色泥岩形成时气候较为稳定,表现为相对湿润且氧化的环境,而绿色泥岩形成时气候波动较大,表现为相对干旱且还原的环境。
The Cretaceous is the most recent “Greenhouse Earth” period, and studying its climate evolution is of great significance for understanding the formation and evolution of today’s climate and environment. The elemental geochemical characteristics of the red and green mudstone in the middle Liwuxia Formation of the Lower Cretaceous Liupanshan Group in the Liupanshan region show that the variation tendency of most of the two mudstone elements is similar. The chemical weathering index (CIA) is similar (average of red mudstone 66.3%, with an average of 65.5% for green mudstone), reflecting mid-low chemical weathering intensity. A-CN-K shows source rocks are single. The analysis of the indexes of CaCO3 content, (CaO + Na2O + K2O) / Al2O3, TFeO / Mn, Ti / Sr, Rb / Sr and Sr / Ba ratio shows that the mudstone color difference is related to the climate background. Stable and relatively humid and oxidized environment, and the formation of green mudstone climate fluctuations, the performance of the relatively dry and reducing environment.