中国东部北黄海盆地白垩纪红色泥岩致色矿物特征及其古环境效应
- 收稿日期:
2023-10-09
- 网络出版日期:
2024-02-29
摘要: 白垩纪在地质历史上曾发生过极端温室气候、全球大洋缺氧以及富氧事件，在此时期出现的白垩纪红层蕴含着重要的古气候和古环境信息，对理解地球表层系统具有十分重要的意义。论文以中国东部北黄海盆地白垩纪发育的一套湖相红色厚层泥岩为主要研究对象，对取自钻井的中侏罗统至下白垩统的红色和灰色泥岩岩心样品分别开展了 X 射线衍射与漫反射光谱分析，半定量-定量分析岩石中致色矿物的组成及含量，并结合普通薄片、扫描电镜等方法观察泥岩中致色矿物的赋存特征，如含铁矿物的形态、分布、晶型大小等。结果显示，红色泥岩致色矿物有赤铁矿和针铁矿，其中以赤铁矿为主，最高含量可达14%，而灰色泥岩中不含赤铁矿和针铁矿；红色泥岩在显微镜下可见赤铁矿集合体，局部可见蚀变现象；扫描电镜下可见赤铁矿呈颗粒状或板状集合体。利用赤铁矿与针铁矿含量变化特征得出气候表现为:晚侏罗世至早白垩世早期气候相对湿润，早白垩世中期至晚期气候以炎热干旱为主。结合岩性特征和北黄海盆地及其邻区资料，发现在研究区内利用铁氧化物反映古气候变化的方法具有可行性，综合分析认为白垩纪红色泥岩中的致色矿物具有一定的古气候与古环境指示意义。
Characteristics of Chromogenic Minerals in Cretaceous Red Mudstones and the Palaeoenvironmental Effect in the North Yellow Sea Basin, Eastern China
- Received Date:
2023-10-09
- Available Online:
2024-02-29
Abstract: During the Cretaceous period, extreme greenhouse climate, global oceanic anoxia and oxygen enrichment events occurred in geological history, and the Cretaceous red beds that appeared during this period contain important information related to paleoclimate and paleoenvironment, which is of great significance to the understanding of stratigraphic surface systems. In this paper, a set of red mudstones developed during the Cretaceous in the North Yellow Sea Basin of eastern China is taken as the object of study. X-ray diffraction and diffuse reflectance spectroscopy (XRD) analyses were carried out on the red and grey mudstones of the Middle Jurassic to Lower Cretaceous, in order 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 chromogenic minerals in the red mudstone, such as the morphology, distribution and crystalline size of iron-containing minerals. XRD results show that the chromogenic minerals in the red mudstone are hematite and goethite, of which hematite is the main content, the highest content can reach 14%, while 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 in the form of granular or plate aggregates under the scanning electron microscope; Using the characteristics of changes in hematite and goethite content, it is concluded that the climate was relatively humid from the Late Jurassic to the Early Cretaceous, and hot and dry from the Middle to Late Early Cretaceous. 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 is found to be feasible, and a comprehensive analysis suggests that the chromogenic minerals in the red mudstone of the Lower Cretaceous have indicative significance for the paleoenvironment and paleoclimate.
岑欣, 王任, 殷科, 石万忠, 李顾盼, 胡小强. 中国东部北黄海盆地白垩纪红色泥岩致色矿物特征及其古环境效应[J]. 沉积学报. doi: 10.14027/j.issn.1000-0550.2024.001
Characteristics of Chromogenic Minerals in Cretaceous Red Mudstones and the Palaeoenvironmental Effect in the North Yellow Sea Basin, Eastern China[J]. Acta Sedimentologica Sinica. doi: 10.14027/j.issn.1000-0550.2024.001
| Citation: |
Characteristics of Chromogenic Minerals in Cretaceous Red Mudstones and the Palaeoenvironmental Effect in the North Yellow Sea Basin, Eastern China[J]. Acta Sedimentologica Sinica. doi: 10.14027/j.issn.1000-0550.2024.001
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