沉积学报2025，Vol.43Issue(6)：1978-1991,14.DOI:10.14027/j.issn.1000-0550.2024.001
白垩纪湖相红色泥岩致色矿物特征及其古环境效应
Characteristics of Chromogenic Minerals in Lower Cretaceous Lacustrine Red Mudstones and Their Paleoenvironmental Effect:A case study from the North Yellow Sea Basin,eastern China
摘要
Abstract
[Objective]During the Cretaceous period,extreme greenhouse climate,global oceanic anoxia,and oxy-gen enrichment events occurred.The Cretaceous red beds that appeared during this period contain important informa-tion related to the paleoclimate and paleoenvironment that aid in our understanding of stratigraphic surface systems.[Methods]In this study,a set of red mudstones developed during the Cretaceous in the North Yellow Sea Basin of eastern China were taken as the object of study.X-ray diffraction(XRD)and diffuse reflectance spectroscopy(DRS)analyses were conducted on the red and grey mudstones of the Middle Jurassic to Lower Cretaceous to semi-quantitatively and quantitatively analyze the composition and content of chromogenic minerals in the rocks.We also combined the ordinary thin section and scanning electron microscope methods to observe the characteristics of chro-mogenic minerals in the red mudstone,such as the morphology,distribution,and crystalline size of iron-containing minerals.The DRS second derivative method was used to calculate the contents of hematite and goethite in mudstone samples.The paleoclimate and paleoenvironment information of red mudstone during its deposition period was obtained by combining the content and ratio of iron oxides in the samples.[Results]XRD results show that the chromogenic minerals in the red mudstone are hematite and goethite,of which hematite is the main content.The high-est content can reach 14%,whereas the grey mudstone does not contain hematite;hematite aggregates can be seen under the microscope in the red mudstone,and alteration phenomena can be seen in the local area;hematite can be seen as granular or plate aggregates under the scanning electron microscope;The DRS second derivative method cal-culated that the average content of hematite in red samples was 1.25 g/kg,and the highest was 2.62 g/kg.The average content of goethite was 0.62 g/kg,and the highest was 1.19 g/kg.Using the changes in hematite and goethite content,the climate was found to be relatively humid from the Late Jurassic to the Early Cretaceous,and hot and dry from the Middle to Late Early Cretaceous.[Conclusions]Combined with the paleoclimate data of the North Yellow Sea Basin and its adjacent areas,the method of using iron oxides to reflect the paleoclimate changes in the study area was found to be feasible.A comprehensive analysis suggests that the chromogenic minerals in the red mudstone of the Lower Cretaceous have indicative significance for the paleoenvironment and paleoclimate.关键词
红色泥岩/致色矿物/古环境/白垩纪/北黄海盆地Key words
red mudstone/chromogenic minerals/paleoenvironment/Cretaceous/North Yellow Sea Basin分类
天文与地球科学引用本文复制引用
CEN Xin,WANG Ren,YIN Ke,SHI WanZhong,LI GuPan,HU XiaoQiang..白垩纪湖相红色泥岩致色矿物特征及其古环境效应[J].沉积学报,2025,43(6):1978-1991,14.基金项目
国家自然科学基金项目(42202121)[National Natural Science Foundation of China,No.42202121] （42202121）
