Monitoring Degree of Metamorphism in a Four-stage Alteration Process Passing from Pure Limestone to Pure Marble

 

Costas I. Sachpazis

Associate Professor, Department of Geotechnology and Environmental Engineering, Technological Educational Institute of West Macedonia, Koila 50100, Kozani, Greece

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ABSTRACT

The Bernician Great limestone from Northumberland England has been divided into four metamorphic grades: (a) un-metamorphosed, grade A, limestone, (b) low metamorphic, grade B, limestone, (c) high metamorphic, grade C, limestone, and (d) completely metamorphosed, grade D, limestone (marble).

Representative samples of these grades were collected, sectioned, their petrography and mineralogy described as well as the gradual influence of contact-metamorphism on its mineral composition, structure and texture determined.

Geotechnical Engineering tests were performed on rock cylindrical cores, and irregular lumps of the four selected grades. Among the tests carried out, were laboratory index tests for characterization, engineering źdesign╗ tests, and weathering simulation tests.

These, revealed the geotechnical properties and behaviour of all four metamorphic grades of the Great limestone and that metamorphism, as a geological agent, has a considerable effect and alteration on the geotechnical engineering properties, as shown by the gradual deterioration of its rock material geomechanical quality, with increasing metamorphosing action.

Finally, a mathematical relationship, using the correlation analysis, can be shown to exist between the geotechnical properties and the petrographic texture and structure of this rock type as metamorphosing action proceeds.

Keywords: geotechnical engineering properties; degree of contact metamorphism; index & physical & mechanical properties of limestone and marble; rock material quality and geomechanical behaviour; mathematical correlation analysis.

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