Some Aspects of Diagenesis of the Broach Group of Tertiary Sediments Around Jhagadia, District Broach, Gujarat

The supra-Trappean Broach Group of Tertiary sediments show evidences of a variety of diagenetic changes. The arenaceous sediments of the Vagalkhod Formation contain proofs of recrystallisation of sparry and micrite cement indicating pore-filling and shallow depth of burial. The calcareous sediments of the Bhilod Formation (Nummulitics) show limonitisation suggesting low temperature metasomatism and precipitation in shallow waters. The argillaceous rocks of the Tarakeshwar Formation reveal authigenic sparite, also indicative of shallow burial. Silica cementation, authigenesis and limonitisation are some of the important diagenetic changes discernible in the overlying rudaceous Babaguru Formation. These changes suggest redoxomorphic stage, precipitation from gel and epidiagenesis. The calcareous sediments of the Kand Formation reveal recrystallisation of spa rite from micrite, which may suggest diagenetic transformation. The arenaceous sediments of the Jhagadia Formation bear evidence of the activity of carbonate cementation ~nd replacement, which may perhaps indicate locomorphic stage of diagenesis.