Despite the variations in primary composition and facies ofBrent Group sandstones the main diagenetic processes areconsidered to be similar for all formations (Bjørlykke et al., 1992).Dissolution of feldspar, the precipitation of kaolinite, and carbonatecementation occurred at shallow depth related to fresh water flow,while albitization of K-feldspar, quartz precipitation and theformation of authigenic illite occurred during burial diagenesis(Bjørlykke, 1983; Bjørlykke et al., 1992; Giles et al., 1992). In theBrent Group, quartz cementation increases significantly at depthsexceeding 3 km (Bjørlykke et al., 1992). Studies of quartz cemen-tation in sandstones from the Norwegian continental shelf (Wal-derhaug, 1994b; Bjørkum, 1996; Oelkers et al., 2000) show thatquartz cementation is a temperature controlled process sourced bydissolution along stylolites and is rather insensitive to changes ineffective stress.
đang được dịch, vui lòng đợi..
