【摘要】 中生代中晚期的燕山运动在中国东南部形成一系列断陷、断拗盆地和火山洼地,其中堆积或沉积了巨厚的火山岩和河湖相碎屑沉积,浙江永康、东阳盆地白垩系馆头组(113 Ma)和朝川组(99~110 Ma)的湖相碳酸盐岩就是形成于这个时期。从岩性、沉积相和生物群特征分析,它们形成于热带雨季、旱季交替气候。早白垩世早期温暖湿润,早白垩世中、晚期向炎热干旱化演变,湖泊蒸发量逐渐大于降雨量,导致湖水中溶解的陆源碎屑碳酸盐浓度不断增加,析出沉淀,形成大量钙质结核乃至大小不一的泥晶灰岩透镜体,到朝川组沉积后期,随着气候更加干旱炎热,湖盆碳酸盐沉积除了在紫红色碎屑岩中形成更多的钙质结核和泥晶灰岩透镜体外,还形成了薄层—中层状泥晶灰岩夹层。更多还原

【Abstract】 A series of fault block basins and volcanic depressions formed in southeastern China were formed due to the middle-late Mesozoic Yanshan movement and were filled with thick volcanic and fluvio-lacustrine sediments.Early Creataceous lacustrine carbonate rocks in the Guantou(99~110 Ma)and Chaochuan(113 Ma)formations in the Yongkang and Dongyang basins are part of this sedimentary fill.Their lithology,sedimentary facies and fossils suggest they were deposited in a tropical wet-dry alternating climate.The climate in southeastern China was warm and humid during the early stage of the Early Cretaceous,and then became hot and arid towards the middle and late stages of the Early Cretaceous.With evaporation gradually exceeding rainfall in Yongkang and Dongyang basins,calcium carbonate became supersaturated in lake waters and in terrigenous sediments,promoting the formation of calcareous concretions and lenticular calsilutite bodies.In the upper Chaochuan Formation,in addition to calcareous concretions and lenticular calsilutite bodies,thin-and middle-bedded calsilutite beds were deposited and interbedded with red siltstones,suggesting hotter and more arid climates.更多还原