山东山旺中新世硅藻土的纹层类型及成因

Types and Origin of Diatomaceous Laminaeof the Miocene Shanwang Formationin Linqu,Shandong Province

山东临朐山旺地区中新世山旺组硅藻土极为发育。通过对该地区硅藻土纹层的研究 ,确定其分类和成因 ,为进一步确立年纹层的存在、利用其进行高分辨率测年、探讨高频古气候旋回奠定基础。山旺组硅藻土的单层纹层厚度一般为 10 0 μm左右。依据纹层的物质成分 ,单层纹层可分为硅藻纹层、有机纹层和粘土纹层三种类型。各类单层纹层组合成为明暗相间的层偶 ,层偶厚度一般为 10 0～ 4 0 0 μm ,常常表现为浅色的硅藻纹层逐渐向深色的粘土纹层或有机质纹层渐变过渡。纹层层偶可分为 :薄层硅藻纹层—有机质层偶 ,厚层藻纹层—有机质层偶 ,薄层粘土纹层—有机质层偶 ,厚层粘土纹层—有机质层偶和硅藻纹层—粘土纹层层偶。山旺组硅藻土中不同类型的单层纹层以及层偶的形成主要受控于当时湖盆内粘土物质的沉积速率、硅藻的繁盛程度和有机物质的沉积和保存条件。

The Miocene Shanwang Formation in Linqu of Shandong Province consists mainly of lacustrine diatomaceous sediments. Detailed sedimentary study on the laminated diatomites in the Shanwang Formation is necessary for the furtherwork on reconstruction of high-frequency climatic cycle. Based on the major mineral composition and their ratios, the diatomaceous sediments in the Shanwang Formation are distinguished as three distinct laminae (clay laminae, diatomaceous laminae and organic matter laminae) and three lamina couplet types (organic matter-clay couplet, organic matter-diatomaceous couplet and diatomaceous couplet- clay couplet). The formation of diatomaceous laminae and lamina couples in the Shanwang Formation was controlled by sedimentary rate of terrigenous clays, diatom growth, and deposition and preservation of organic matters in the basin.