Microstructural evidence of restite is meagre or absent in high-level metaluminous (I-type) granitic plutons, and is limited in high-level peraluminous (S-type) granitic rocks. The microgranitic enclaves (autoliths, 'cognate xenoliths') that occur abundantly in both metaluminous and peraluminous granitic rocks are probably formed by quenching of magma in the plutonic environment. The enclaves are best explained by mingling and quenching of globules of more mafic magma in the host granitic magma, although some may be solid fragments of quenched magma. Several quenching processes are feasible, provided incorporation of partly liquid material is postulated. However, mineralogical and microstructural evidence of hybridism suggests that many microgranitic enclaves may be the result of magma mixing, either in the same reservoir as the host granitic rock or elsewhere.-N.C.N.S.
|Number of pages||27|
|Journal||Journal & Proceedings, Royal Society of New South Wales|
|Publication status||Published - 1983|