Generation of subsurface injection flow in a carbonate platform

摘要

In order to diagnose emplacement of discordant breccia body in carbonate platform, we here describe sedimentary structures and texture as well as bed geometry of two beds of the Chaomidian Formation (Frongian) in Shandong Province, China. Each breccia body consists of granule- to cobble-size clasts of peloidal grainstone and matrices of dolomitic marlstone and/or micritic limestone, showing a tunnel geometry. Marlstone in the matrix is homogeneous, whereas micritic limestone shows irregular and disoriented laminations. It is hypothesized that the breccia body formed by subsurface in situ fluidization and fragmentation and further injection into the ambient deposits. Subsurface sediment remobilization occurred most likely under cyclic loading of large storm waves. The laminated matrix is strongly suggestive of hydroplastic deformation (flowage) of fluidized material during injection. This study suggests that there exists a full spectrum of subsurface deformation from liquefaction/fluidization to injection flow.