I noticed that in some data related to sidewall cores (SWC) analyses of clastic reservoir deposited in shallow marine environment (deltaic env.). some XRD samples shows a high concentration of siderite (up to 50%) and other samples have less than 10% and in some others samples there is no trace of siderite.
Is there any explanation for this high concentrations of siderite intervals, in term of depositional setting ? or it may be related to other factors ? if yes what are these factors ?