Journal of Petroleum Geology, Vol.14, No.2, pp. 221-228, 1991

©Copyright 2000 Scientific Press, Ltd.

THE ORGANIC GEOCHEMISTRY OF HYDROCARBON GASES
IN FLUORITES FROM NORTHERN ENGLAND

J. Ferguson*

* Imperial College, Prince Consort Road, London SW7 2BR

Abstract

A study of the light hydrocarbon gases which occur in saline fluid inclusions in fluorite from the Alston Block area of the Northern Pennine Orefield (NPO), is reported. Reproducibility of the data is demonstrated by comparing the analysis of samples collected on two separate occasions. Although it has not proved possible to use the technique to differentiate zones in individual crystals, it has been shown that there is a good correlation between the amount of gas and the nature of the mineral. Thus, massive fluorite contains roughly twice the total amount of gas as single crystals. The balance of saturated to unsaturated gases is shown to be dependent on the temperature of emplacement of the mineral. A comparison of this data with data obtained earlier from minerals from the Askrigg Block and Derbyshire Dome has confirmed these findings. The relationship between these saline fluid inclusions, and those filled with oil from Derbyshire and elsewhere, has led to speculation on the nature and timing of the fluids responsible for mineralization.