Describe and explain the nature of Igneous body A and explain the distribution of olivine and its significance?

Igneous body A intrudes concordantly into the country rock and has baked and chilled margins on both sides of the igneous contact. This show's that is a structure known as a sill.The Olivine forms a band parallel to one of the contacts. This distribution occurs due to Olivine being the highest temperature mineral to crystallise out of the melt which can be seen on Bowen's reaction series. The crytals are denser than the surrounding magma and through gravataional settling sink through the magma to form a band of olivine cummulates. The presence of Olivine in the sequence indicates a slow cooling history, therefore the sill formed in the lower crust. Also the band of olivine must form at the base of sill due to gravity which shows whether it's the right way up. In the case of igneous body A the band is at the top of sill, which show's that the sequence has been overturned.