Mineral and Organic Distributions and Relationships Across the Green River Formation's Saline Depositional Center, Piceance Creek Basin, Colorado

摘要

Stratigraphically correlated profiles of organic matter concentration and profiles of 8 major mineral x-ray diffraction peak heights in oil shales, through Colorado's Green River Formation near its saline depositional center, are presented in histogram form. The profiles are used to show distributions and relationships of the minerals and organic matter. Strong direct relationships between the volume of organic matter in Colorado's Green River Formation oil shales and the relative amounts of the silicate minerals--quartz, soda feldspar, and potash feldspar-- were demonstrated singly and collectively. The silicate minerals were also shown to be directly related to each other. Dawsonite in the saline zone of the Formation was also shown to be directly related to the volume of organic matter and indirectly to the amount of nahcolite. These relationships were all interpreted as the results of CO sub 2 evolution from organic matter in the sediment. A strong direct relationship demonstrated between dawsonite and quartz was credited to both the organic CO sub 2 mechanisms and to ash-fall decomposition. Significant non-correlation with organic matter or any of the other minerals was found for calcite and analcime. Lack of significant correlation among any of the components in one particular section demonstrated absence of geochemical control during its deposition. The relationships provide an additional interpretive tool for the Green River Formation. (ERA citation 04:021599)