The geology study of Tolo Habour area based on integrated geophysicial and borehole geology data

Abstract

The marine geophysical survey is more economic comparing to the traditional borehole investigation in sea, which can provide a larger extent surveyed area and many data points. The objective of this project is to review and utilize the geophysics surveyed data, and incorporate with borehole geology data in Tolo Habour, in order to reconstruct the geological model of the study area.

The scope of study area includes Sha Tin Hoi area, and it extends to offshore of Tai Po Industrial Area. The source of the information is mainly based on the updated geophysical surveyed data in EGS report 2013, and the existing borehole reports. The geological map and the related reports and memoir are reviewed. The various geological layers contour plans, cross section, 3D models, and solid geology in the study area are constructed.

The Hang Hu Formation marine deposit and the Check Lap Formation alluvium deposits are the major superficial deposits in the studied geological model. In the southern part of the study area, the diamict, and karst deposits are deposited in marble zone. The northwestern part of the study area, the majority of the rock is Jurassic Yim Tin Tsai Formation tuff, and this formation is locally intruded by the Jurassic Tai Po Granodiorite. The Jurassic Tai O Formation sedimentary rock forms the middle part of the study area. In southwestern part, the Jurassic Shatin and Needle Hill Granite are present with Carboniferous Ma On Shan Marble wedge, which is mainly bounded by the faults.

The geophysical survey method and the borehole investigation can provide the supplementary data to each other, but both methods have their limitations which should be understanding and considering during the ground investigation planning in order to acquire the necessary information.