| Autor: |
Andrew C. Aplin, Cathal G. Dillon, Delphine Charpentier, Richard H. Worden |
| Rok vydání: |
2003 |
| Předmět: |
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| Zdroj: |
Journal of Geochemical Exploration. :459-463 |
| ISSN: |
0375-6742 |
| DOI: |
10.1016/s0375-6742(03)00073-6 |
| Popis: |
Geostatistical image analysis of backscattered electron microscope (BSEM) images has been used to determine the degree of alignment (anisotropy) of clay minerals in late Tertiary mudstone samples from a range of depths from the Gulf of Mexico. This has been tied to mineral chemical analysis using secondary X-rays to determine whether fabric development is related to mineral diagenesis. Although compacted, mudstones at ∼ 5100 m have isotropic clay fabrics. Thousands of meters of overburden and the resulting stress have not induced the development of aligned fabric in mudstones. Mudstones adopt a progressively more anisotropic fabric with increasing depth of burial to ∼ 5600 m. Smectite is progressively replaced by illite with increasing depth over the same interval so there is a close correspondence between the illitization of smectite and fabric development. The fabric seems to be a consequence of mineral diagenesis. The kinetically controlled illitization of smectite has facilitated the development of fabric which is thus likely to be due to a dissolution and reprecipitation process rather than a solid-state process. Fabric development, with its consequences for porosity and permeability, is thus more likely to be a function of temperature and the thermal history rather than just depth and effective stress. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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Full Text from ScienceDirect