摘要
在松辽盆地上白垩统青山口组中首次发现核形石灰岩,见于细砂岩、粉砂岩和泥质岩层系中。核形石有三种类型:环状、石笋状和姜状核形石。多数核形石由核心和多环纹层组成,少数具不明显核心或呈单层环状。该套核形石形成于湖泊三角洲前缘分流河口砂坝侧翼的水下分流间湾环境。地形坡度和三角洲前缘的生长,致使核形石普遍发生准同生变形。由于核形石出现于青山口组二、三段,处于温湿向干热气候转变时期,因此核形石可能作为重要的古气候变迁标志。
Oncolitic limestone was firstly discovered in the Qingshankou Formation of Cretaceous in Songliao Basin. It occurs primarily in fine-grained sandstone, siltstone and the mudstone. Based on the metamorphic features, the oncolites from the study area can be divided into three types： annular oncolite, stalagmite oncolite, and ginger-shaped oncolite. Most oncolites are composed of a core and multi-ring lamina, but minor amount doesn＇t have distinct core or monolayer lamina. Research indicated that the oncolites formed mainly in the underground shallow bay environment of lake delta front. The penecontemporaneous deformation of the oncolites is attributed to growing of topographic slope and deltaic front. The fact that the oncolites occur in the second and third sections of the Qingshankou Formation indicates a transitional period from humid to dried and hot climates, and therefore, the rock can be considered an important index of paleoclimate changes.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2008年第5期594-600,共7页
Acta Geologica Sinica
基金
国家重点基础研究发展计划项目(编号2006CB701403)资助的成果
关键词
松辽盆地
白垩系青山口组
核形石
沉积环境
古气候标志
Songliao Basin
Qingshankou Formation of Cretaceous
oncolite
depositional environment
paleoclimatic mark
