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Plate 48 - Sandy Beach at Fan Lau Sai Wan (025 073), with Quartz Syenite Exposed near the Jetty, andFine-grained Granite on the Hills to the South120
of uncertain stratigraphical significance have been recognised, associated principally withlarge-scale erosional and depositional events during the last sea-level lowstand and thesucceeding transgression. However, the basal part of this unit may include sediments thatpre-date these events,The major formation- or sequence-bounding reflectors have been correlated with borehole, conepenetration test, and vane test data. The reflectors generally correspond to significant changes ina number of parameters, including lithology, geotechnical properties, palaeontology andgeochemistry. However, difficulties of interpretation and correlation arise where minor variationsin facies and lithology occur laterally across, and vertically through a deposit, but these changesare not clearly displayed on the seismic records. These subtle changes within and acrossformation and sequence boundaries have led to the inclusion of two facies within the offshoredeposits that are based on their genetic character; marine sand sheets and marine sand banks.Within the Pearl River (Zhujiang) Estuary, a twofold stratigraphical division has been describedby Long and Huo (1990), comprising a lower Zhongshan Formation (40 000 to 12 000 BP) andan upper Shunde Formation (12 000 BP to Present). Both formations have been subdivided intothree units. From the limited published descriptions, the lower unit of the Zhongshan Formationappears to be the equivalent of the Chek Lap Kok Formation, the middle unit of the ZhongshanFormation matches the features of the Sham Wat Formation, and the middle and upper units ofthe Shunde Formation are similar to those of the Hang Hau Formation (Shaw & Fyfe, 1992).Over most of the offshore area of the district there is a thick mantle of superficial deposits, withrock exposures at the sea bed confined mainly to shoals such as Pun San Shek (2510 2030), tonearshore exposures, and to areas swept by currents with relatively high velocities, such as thenarrow channels of Kap Shui Mun (2400 2230) and around Tsing Yi (2630 2300). Thesuperficial deposits generally lie on a rock surface that is steeply inclined near the coast,continuing the generally steep coastal slopes. The slopes tend to flatten out at c. -20 to -30 mPD,although in some places close to the coastline they descend to lower than -50 mPD. Away fromthe coast, the superficial deposits commonly infill broad, relatively smooth depressions, althoughthere are areas, such as around Sha Chau and The Brothers islands, where the superficialdeposits onlap and thin over local rock highs.A number of factors control the thickness of the superficial sediments. These include the formand elevation of the rock surface, tidal currents, the sediment sources and their depositionalenvironment. These are in turn influenced by the proximity of the coastline. For example, in arelatively narrow tidal channel north of Lantau Island, between Ma Wan and Sha Chau,superficial sediment thickness varies from zero around Ma Wan to about 50 m at the Territory'sboundary west of Chek Lap Kok, Within the central part of the tidal channel, superficialsediments can be relatively thin (
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UNIVERSITY OF HONG KONGLIBRARIES
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© Government of Hong KongPublished
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CONTENTSTitle pagePage1ForewordCont
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Distribution and Lithology 73Detail
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Chapter 10 Economic Geology 149Intr
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(Plates)Plate 22 - Porphyritic Medi
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Table 1 — Grain Size Description
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0 1 2 3 4 5 k mCONTOURS AT 100m INT
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properties of the marine deposits b
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Archival DataAll records from the s
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Chapter 2Outline of GeologyThe soli
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The Mesozoic volcanic rocks are div
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Chapter 3Palaeozoic Sedimentary Roc
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Carboniferous metasedimentaiy rocks
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Plate 1 - Fining-Upward Sequence of
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Plate 3 - Well-bedded Sandstones an
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Reef Island. The northern end of th
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Table 3. Evolution of Nomenclature
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are crudely stratified and welded i
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Shing Mun FormationThe type localit
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Tai Che Tung. Crystal tuff, interpr
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Plate 7 • Lapilli-Ash Crystal Tuf
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Plate 11 - Pyroclastic Breccia (086
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appears fragmental, and contains mu
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exposures in the stream bed consist
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Lin Fa Shan. The steep eastern flan
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dipping northwest at 46°, is prese
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Sunset Peak MemberThe Sunset Peak M
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Plate 16- Block and Lapilli-bearing
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Chapter 5Major IntrusionsClassifica
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in grain size from 0.4 to 1.5 mm, a
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20 - Megacrystic Medium-grained Gra
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Pui O Wan. Porphyritic medium-grain
Page 71 and 72: minimum age of c. 145 Ma (see earli
Page 73 and 74: The granite on Chek Lap Kok is most
Page 75 and 76: Southeast of Tin Sam, on the wester
Page 77 and 78: About 1 km east of Nam Shan, exposu
Page 79 and 80: Plate 25 - Thin Section of Porphyri
Page 81 and 82: Chapter 6Minor IntrusionsIntroducti
Page 83 and 84: The microgranite grades southwards
Page 85 and 86: the Lantau Formation, however, and
Page 87 and 88: Plate 29 - Flow-banded Quartzphyric
Page 89 and 90: also cut volcanic rocks of the Tsue
Page 91 and 92: Silver Mine Bay. On the headland so
Page 93 and 94: Plate 33 - Core stone Development i
Page 95: Plate 37 - Thin Section ofLamprophy
Page 98 and 99: Pre-Yensfaanlan StructureWithin the
Page 100 and 101: separates areas of different lithol
Page 102 and 103: NeotectonicsFault activity in the r
Page 105 and 106: Chapter 8Metamorphism and Alteratio
Page 107 and 108: the majority of rocks in the distri
Page 109: Chapter 9Superficial GeologyIntrodu
Page 112 and 113: Detailstal O. Alluvial deposits for
Page 114 and 115: trains. The regolith on most steep
Page 116 and 117: Plate 44 - Boulder Debris on the So
Page 118 and 119: gazetted for recreational purposes.
Page 120 and 121: DetailsTai O. Extensive intertidal
Page 124 and 125: Pre-Chek Lap Kok Formation Deposits
Page 126 and 127: formation. The sequence is usually
Page 128 and 129: BOREHOLE NO: ESC 17GRID REFERENCE:
Page 130 and 131: BOREHOLE NO: A5/1GRID REFERENCE: 80
Page 132 and 133: formation, thinly laminated clays o
Page 134 and 135: Quinqueloculina seminulum, which is
Page 136 and 137: Channel and Transgressive Deposits.
Page 138 and 139: Figure 20 - Areas of Acoustic Turbi
Page 140 and 141: West Lamma Channel These may be att
Page 142 and 143: Figure 23 - Depth-Averaged, Maximum
Page 144 and 145: The formation is Holocene in age. T
Page 146 and 147: Boreholes (A5/1, A5/2, B2/1, ESC17
Page 148 and 149: Plate 51 - Deep Weathering Profile
Page 151 and 152: Chapter 10Economic GeologyIntroduct
Page 153 and 154: Non-metalliferous MineralsFissure v
Page 155 and 156: REFERENCESAddison, R. (1986). Geolo
Page 157 and 158: James, J.W.C. (1993). The offshore
Page 159 and 160: Sewell, R.J., Strange, PJ., Langfor
Page 161 and 162: Appendix 1Microfossils identified f
Page 163 and 164: Appendix 2 (continued)Sample HK9913
Page 165 and 166: Appendix 2 (continued)Sample HK1054
Page 167 and 168: Appendix 4aSelective normalized pal
Page 169 and 170: ,Appendix 5 -Radiocarbon and Other
Page 171 and 172: construction materials 151contact m
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molybdenite 149Mong Tung Hang 151Mo
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talus 107,115Tarn Tsui Wan 71,87Tan
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LB 555.125 G34 LGeology of Lantaii
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