Quartz cements in the Cambrian sandstones, Żarnowiec region, N Poland: a fluid inclusion study

Abstract

Fluid inclusion studies were conducted in quartz cements of the Cambrian sandstones from two boreholes in the Żarnowiec region (northern Poland). The research based on the microscope observations of inclusions aiming at their petrography and fluorescence characteristics as well as it comprised the routine microthemometric runs. The cathodoluminescence studies resulted in determination of generations of quartz cementing the sandstones. Two types of fluid inclusions have been found - aqueous and hydrocarbon ones. They are connected with two generations of the quartz cements in the sandstones under discussion. The aqueous inclusions yield homogenisation temperatures of about l00°C and salinities of about 8% eq. NaCI. The hydrocarbon inclusions studied display three temperature groups ranging from 71 to 110°C. An attempt of interpretation of the entrapment conditions of coeval oil and aqueous inclusions was made resulting in p-T values. Due to the limited number of fluid inclusions in the cements the representativeness of the data is, however, rather poor.