CHEMICAL COMPOSITION OF THE FLUID PHASES FROM MICROINCLUSIONS IN MINERALS LIFTED FROM THE SG-4 ULTRADEEP DRILLHOLE IN THE URALS

Abstract

The data from cores of deep and ultradeep drillholes allow us to identify the depths associated with the various temperature intervals (i.e., the depths at which various volatile components were liberated), the compositions of the inclusions and the ratios of the phases present at various depths, as well as differences in the compositions and elemental ratios of the phases that separated at the low and high temperatures. In the present paper we describe the chemical composition of fluid inclusions from some minerals identified in cores from the SG-4 drillhole lifted from various depths shallower than 2400 m. The composition of the volatiles extracted from the minerals was analyzed by mass spectrometry and thermography. The results indicate the following. 1. As depth increases, so does the fraction of water that must be liberated from the minerals at high temperatures. In most cases, the water and other volatiles were liberated simultaneously. The ratios of CO2 and H2O in the inclusions increased markedly with the depth from which the cores were lifted. 3. The number of discrete stages in the liberation of volatiles from the inclusions increases with the depth of sampling, i.e., their liberation becomes more discontinuous. 4. The ratio of reduced and oxidized forms of carbon (e.g., the ratio of CH4 to CO2) tends to decrease with depth, at least down to 2100 m. 5. The ratio of light hydrocarbons (CH4) to heavier hydrocarbons (C2H6, C3H3) tends to decrease with depth (from 290 to 2400 m). All of the specimens from the drillhole tend to be relatively rich in hydrocarbons.