Table 6.2a - Summary of the field and petrographic characteristics of the Lamma Suite, 'I-type' Subsuite

LAMMA SUITE
'I-type' Subsuite
UNIT Tai Po
Granodiorite
Lantau
Granite
Colour grey grey
Rock Type Hornblende-biotite granodiorite hornblende-biotite monzogranite
Dominant texture porphyritic medium to fine grained porphyritic coarse to fine grained
Mafic minerals hornblende, biotite hornblende, biotite
Feldspar orthoclase zoned oligoclase microcline mesoperthite zoned oligoclase
Accessory minerals zircon, titanite, apatite, allanite, Fe-oxide zircon, allanite, titanite, Fe-oxide
Alkali feldspar megacrysts common common
Pluton shape irregular irregular
Area exposed (km2) 30 35
Mineralization Mo -

Table 6.2b - Summary of the field and petrographic characteristics of the Lamma Suite, 'A-Type' Subsuite

LAMMA SUITE
'A-Type' Subsuite
UNIT Chek Mun
Rhyolite
Chek Lap Kok
Granite
Tai Lam
Granite
Tsing Shan
Granite
Colour light grey or white white light grey or white light pinkish grey
Rock Type quartzphyric rhyolite monzogranite biotite monzogranite biotite monzogranite
Dominant texture porphyritic fine grained equigranular fine grained porphyritic medium to fine grained porphyritic coarse to fine grained
Mafic minerals biotite biotite biotite biotite
Feldspar orthoclase albite mesoperthite albite orthoclase albite microcline, mesoperthite, zoned oligoclase
Accessory minerals zircon, apatite zircon, fluorite, Fe-oxide zircon, allanite, muscovite, fluorite zircon, allanite, monazite
Alkali feldspar megacrysts absent absent common common
Pluton shape (dyke swarm) circular elliptical elliptical
Area exposed (km2) <1 11.5 80 40
Mineralization - F Mo,Pb,F,Zn,Cu,Be,W,Sn Mo,Sn,W,F

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