GENERAL GEOLOGY OF THE LIMESTONE AT SELECTED SITES IN THE NORTHWEST PART OF PENINSULAR MALAYSIA WITH EMPHASIS ON THE IMPACT OF VARYING DEGREE OF METAMORPHISM ON THE ROCK’S TRIAXIAL STRENGTH AND SOME PETROPHYSICAL PROPERTIES.

In geological terms, metamorphism bears the meaning of changes in mineral assemblage and texture; this is the resultant effect of subjecting a rock to elevated amount of heat and pressure which differs from the original condition in which the rock was formed. Samples of carbonates and detrital bands of the Ordovician to Lower Devonian, and Devonian to older rocks from selected areas within the Northwestern domain of Peninsula Malaysia varying in terms of metamorphism were collected and the degree of the effect of metamorphism on the sample were identified via microscopy analysis and field observations, x-ray diffraction (XRD) and energy dispersive scan (EDS) were mainly used to supplement mineral identification from microscopy analysis. In addition to that, geological maps were produce for each outcrop studied to further comprehend the general geology of the study area. Since, the lithology of interest of this study is on limestone and dolomite which is essentially made up of either minerals calcite or dolomite, metamorphism on this type of rock would result in the original calcite/dolomite crystals growing larger to form marble or dolomitic marble. The strength or the load that a mass of solid rock can withstand before failing is an important aspect in geotechnical parameter for engineering purposes not only in the oil and gas industry but also in for construction and mining purpose. The strength of a rock is influenced by its textural and mineral characteristics. Therefore, it can be postulated that with varying degree of metamorphism which alters the textural and mineralogical arrangement of the rock in terms of grain size and grain to grain contact coupled with other parameters such as structural environment and other geological defects, some level of variation on the strength of the rock would also be observed. From the results a trend appears whereby as the degree of metamorphism becomes more prominent, the shear strength increases and porosity decreases, in terms of thermal conductivity, the values obtained are more point-dependent. Through this study it was identified that