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separates areas of different lithologies, while other faults in the set offset major geologicalboundaries; for example the Tung Chung Fault displaces the contact between Tsuen WanVolcanic Group and the Lantau Formation. This set also appears to offset some other faulttrends, including the eastnortheast-trending North Lantau Fault Zone (discussed below).A magnetic survey of North Lantau Harbour (Electronic and Geophysical Services, 1991) hasalso identified a series of northwest trends along which anomalies are displaced, and these areinterpreted as faults.Major quartz veins, up to 25 m wide, at Sha Lo Wan, Yam Tsai and Tsing Chau Tsai also trendnorthwestwards and are likely to be associated with northwest-trending faults. In some places theveins contain breccia of country rock; for example the granite blocks in a quartz vein at Hau HokWanThrust faultFaultCaldera boundary faultThe Brothers Islandsx"M~"Peng Chauf : ( Hei Ling ChauCheung ChauSyeniteRhyolite Dyke ComplexGraniteRepulse Bay Volcanic GroupTsuen Wan Volcanic GroupCarboniferousFigure 10 - Solid Geology of the District, Showing the Main Faults Inferred from AH Data SourcesNortheast-trending Faults (andphotolineaments)Strong northeast-trending lineaments on air-photographs and satellite images are inferred to beone set of faults. One of the clearest, between Yam 0 and Pui 0, apparently smistraliy offsetsgramte and syenite contacts by about 1 km. Some similarly-trending, small-scale faults also showapparent simstral displacements (Plate 39). Other lineaments in this set cross major geologicalboundaries with no apparent offset, such as the lineament west of Tung Chung which crossesboundaries between granite and syenite, and syenite and Lantau Formation98