백악기 연질퇴적변형구조의 산상 및 성인과 퇴적암내 유체유동의 구조적 제어

Abstract

Deformation structures are commonly observed in sedimentary rocks that is important in many fields of geology such as fluid flow and site evaluation of major nation facilities. In this dissertation, I mainly investigated soft-sediment deformation (SSD) structures and post-depositional structures in the sedimentary rocks based on detailed geological survey, qualitative and quantitative analysis together with geochronological and geochemical method. First, I studied the SSD in the late Cretaceous Wido Volcanics, Southwestern Korean Peninsula that focused on characteristics of syn-depositional deformation structures and interpretation of their origin and trigger agents. I conclude that the earthquakes that caused the development of SSD structures in the study area were closely related to syndepositional magmatic activities, as is the case for modern tectonic earthquakes around active volcanoes. Next, I researched the SSD in the Late Cretaceous sedimentary-volcanic successions such as Buan, Uhangri and Dadaepo area as well as Wido area, Southern Korean Peninsula. I carried out field survey and geochronological analysis in order to investigate relationship between timing of SSD and volcanic activity during the Late Cretaceous in the Korean Peninsula. I conclude that the timing of SSD exactly coincide with peak of magmatic activities during the Late Cretaceous in the Korean Peninsula. Lastly, I investigated different types of bleaching patterns in order to understand the factors that controlled their development, along with the leakage process of paleo-fluid flow in a reservoir-cap rock system. I demonstrate that bleaching is primarily controlled by the lithological properties (e.g., permeability or porosity) of the reservoir-cap rock system; however, structural discontinuities (e.g., faults or fractures) can also strongly affect it. In addition, multiple layered sedimentary rock shows different damage zone width and characteristics of fluid flow. This study provides new insight into understating of syn- and post-deformation structures in sedimentary rocks. In addition, fluid-flow processes and rock-fluid interaction in sedimentary rocks. Our results may also be very useful in evaluating the feasibility of geological sites for CO2 sequestration and HLW disposal, particularly for identifying potential CO2 leakage in a reservoir-cap rock system and formulating related hazard assessments.