Dear Josiah Oluwaleye.

There are some structural and petrography criteria to identify granitic cumulates, and they are summarized by Vernon & Collins in the attached paper.

I hope this could help you

Best regards

Using bulk-rock geochemistry to identify the cumulate origin of any coarse grained rock is fraught with uncertainty and should not be used without careful consideration of the petrology of the rock on the hand-specimen and microscopic scale, and by looking at structural information on the outcrop scale. Imagine taking a fist-sized sample of a granitic rock. It may only contain one or two k-feldspar megacrysts, hidden from view in your hand specimen, but volumetrically these could make up the bulk of the sample. Any whole-rock analysis may very well just end-up looking like a slightly-odd k-feldspar analysis, and will tell you nothing of the origin of the rock as a whole!

Cumulates have distinct textures and they are relatively well sorted. Geochemistry will not help you in this case and you need to look at thin sections!

Okay Cesar Alfredo Tarazona Velasquez Daniel Müller Jeremy Preston . Thanks for your replies.

I have found that it is difficult to determine the amount of cumulate versus adcumulus minerals based on single specimens examined under the microscope in most instances. I have found it very useful to have a traverse of thin sections of specimens from the pluton margin in to where the grain size remains similar to the bulk of the pluton. that way you start from a pretty clear idea of what the crystal content of the pluton is and can see the changes that occur with slower cooling and overgrowths on cumulate or at least early crystal content formed prior to intrusion to the depth now exposed. Very empirical and time consuming but you will have a good idea of what is going on. lots of touching euhedral crystals with minor late stage interstitial minerals are the simplest to assign to cumulte facies rocks, but if the magmatic proportion is of felsic composition then your observations to determine if the rock is a cumulate are going to be critical.