As already shown (Section 3.1), lamprophyres are overwhelmingly hypabyssal, medium-grained intrusions. Although LL commonly exist as volcanic rocks, and AL and CAL do so rarely, KIL and UML almost never do (Section 3.1.7). Again, although relatively coarsegrained (e.g. pegmatoidal) segregations do exist in some dykes (e.g. Macdonald et al. 1986), no example of a true lamprophyre ‘pluton’ has ever been identified. Because most writers can see no intrinsic reason for this (R.H.Mitchell 1986, p.43 found the absence of ‘plutonic kimberlite’ particularly strange), this raises the question of whether other named plutonic or volcanic rock-types might be equivalent to lamprophyres. The old suggestion that LL are simply volcanic lamprophyres (Section 1.3.1) can be dismissed — they are merely one type of lamprophyre — but other suggestions deserve more careful attention.
KeywordsCrystallization Quartz Geochemistry Coherence Calcite
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