Analysis of slump structures at Lai Chi Chong, Eastern New Territories

Abstract

The Lai Chi Chong coastal succession is a site of special scientific interest (SSSI) in Hong Kong. It is located in the Northeastern New Territories along the southern coast of the Tolo Channel. The 500-m-long outcrop exposed along the shoreline is a unique locality as it is one of the few locations in Hong Kong where soft sediment deformation structures such as convolute bedding, slump structures and dewatering structures can be recognized. Among these, only slump structures are generally used to determine the orientation of the palaeoslope, the initial dip direction of the slope at the time of deposition. Moreover, the Lai Chi Chong Formation consists of a variety of sedimentary, volcaniclastic and pyroclastic rocks despite the relatively small area of exposure. The aim of this study was to investigate the geology of Lai Chi Chong and gain an improved understanding of the associated slump structures through field mapping and literature review in order to determine the palaeoslope direction using statistical methods. Although a southerly directed palaeoslope has been proposed by previous authors (Campbell & Shaw 2002), the palaeoslope orientation has not yet been determined using the more robust quantitative methods applied in this dissertation. The study will also draw upon observations of the geology of the Dead Sea Basin where similar soft sediment deformation structures have been observed to better appreciate the underlying processes at work in addition to the different methods of palaeoslope estimation. Based on five different techniques, the results appear to confirm a SE to S-directed palaeoslope, which would be consistent with earlier findings.