Chemical, mineralogical and textural properties of the Kope Formation mudstones: How they affect its durability
| Autor: | Nadeesha H. Koralegedara, J. Barry Maynard |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Outcrop
0211 other engineering and technologies Mineralogy Stratigraphic unit Geology 02 engineering and technology Geotechnical Engineering and Engineering Geology 01 natural sciences Durability Matrix (geology) 010503 geology Oil shale 021101 geological & geomatics engineering 0105 earth and related environmental sciences |
| Zdroj: | Engineering Geology. 228:312-322 |
| ISSN: | 0013-7952 |
| Popis: | The Kope Formation is a rock unit that extends over southwest Ohio and adjacent areas of Kentucky and Indiana, USA. It is characterized by meter-scale cycles of mudstones and limestones where thick mudstone is sandwiched between thin limestone layers. Kope Formation mudstones are less durable than the mudstones in the area. They cause abundant slope failures in areas of their outcrops. This study evaluates chemical, mineralogical and textural properties of Kope mudstones to determine why it is less durable. The Two-cycle slake durability index (ID 2 ) was measured on thirty mudstones belonging to three consecutive cycles of the Kope Formation. Chemical composition and mineralogy of Kope mudstones do not show significant relationship with the ID 2 . Instead, a relationship to fabric was found. Kope mudstones with two main fabric types were observed in the field; laminated mudstones and non-laminated mudstones. Detailed micro-fabric analysis on Kope mudstones was done using the scanning electron microscope. Laminated mudstones with turbostratic fabric showed higher ID 2 and lower moisture content than the non-laminated mudstones with matrix fabric. The difference in the ID 2 of laminated mudstones and non-laminated mudstones is statistically significant. Both mudstone types exist in many cycles of the Kope Formation. Thus, core samples should be selected from both types for preliminary tests in geotechnical practice, to obtain more accurate estimations of the geotechnical properties of the Kope mudstones. The results and data interpretations of this study can be correlated with the mudstones and shale in different areas of the world. Specifically, a great attention should be paid to the macro and micro textural properties of any rock type regardless of their classification. |
| Databáze: | OpenAIRE |
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