The Early Cambrian Mianyang-Changning Intracratonic Sag and Its Control on Petroleum Accumulation in the Sichuan Basin, China

Table 3

Differential diagenesis of Early Cambrian Longwangmiao Formation across the intracratonic sag.

Well	JS-1	GS-17	MX-12
Location	Western margin of sag	Center of sag	Eastern margin
Lithology	Crystalline dolomite	Dolomitic grainstone, crystalline dolomite	Dolomitic grainstone
Mudstone recrystallization	No	Weak	Weak
Dolomitization	Strong	Strong	Strong
Cementation	Weak	Moderate	Strong
Freshwater karstification	Weak	Moderate	Strong
Compaction, pressure solution	Moderate	Moderate	Moderate
Recrystallization	Strong	Strong	Strong
Epigenic karstification	Weak	Moderate to strong	Moderate
Hydrothermal dolomite	Moderate	Strong	Moderate
First charging of hydrocarbon and bitumen	No	Moderate	Strong
Second charging of hydrocarbons	No	Moderate	Strong

(For locations, see Figure 1.)