通化盆地早白垩世混积碎屑岩类型与沉积模式

Types and sedimentary model of Early Cretaceous peperites in Tonghua Basin

通化盆地为一个火山--沉积共同作用的中生代断陷盆地。下白垩统发育果松组、鹰嘴砬子组、林子头组、下桦皮甸子组、亨通山组和三棵榆树组,为火山岩-沉积岩充填,岩性及岩相类型复杂。盆地发育特色的火山--沉积成因的混积碎屑岩,依据钻井岩芯,可以识别出混积粗碎屑岩、混积细碎屑岩和熔岩-碎屑熔岩等三组岩石类型。根据岩石组分、粒度特征区分出水下热碎屑流、水下基浪流、水下火山泥石流、熔岩流及火山碎屑浊流5种岩相类型。建立了通化盆地早白垩世混积碎屑岩的发育模式,明确了构造-火山作用下的混积盆地充填特征,认为盆地早白垩世火山-沉积旋回是盆地周期性走滑伸展的产物。

Tonghua Basin is a Mesozoic faulted basin controlled by coefficient volcanism-induced sedimentation,which comprises Early Cretaceous Yingzuilazi, Linzitou, Xiahuapidianzi, Hengtongshan and Sankeyushu formations. There exists a volcanic-sedimentary sequence with complicated lithologic-petrofacies and characteristic peperites formed by volcanism-induced sedimentation. Three types of rocks are identified on the basis of the drill cores including coarse peperites,fine peperites and lava-pyroclastic lava. Five facies types can be recognized based on rock components and grain size,namely subaqueous pyroclastic flow,subaqueous surge,subaqueous lahar,lava flow and pyroclastic turbidity current. The model of peperites is established and the characteristics of basin filling under the tectono-volcanism are made clear. Research indicates that volcano-sedimentary cycles of the Early Cretaceous in Tonghua Basin are produced by periodic strike-slip and extension.