Petrography, geochemistry and physico-mechanical properties of dolerite from Oghi (Mansehra), Khyber Pakhtunkhwa, Pakistan
Keywords:
Dolerite, Petrography, District Mansehra, Mechanical properties, Aggregate, Dimension stone.Abstract
Dolerite dykes having excellent exposures around Maira Chanser and Jodan Khatta areas of District Masehra are studied in terms of their suitability for aggregates and dimension stone using a combination of petrographic, geotechnical and geochemical characteristics. Petrographically, these rocks, known as black granites in commercial market, are fine to medium-grained having ophitic to sub-ophitic texture. Plagioclase and clinopyroxene occurs as the major mineral phases, whereas opaques, quartz, biotite, amphibole, olivine, apatite, chlorite, orthopyroxene and epidote constitute minor to accessory phases. Geochemically, these dolerites show sub-alkalic, metaluminous, tholeiitic to alkalic basalt character and fall in gabbroic category. These rocks have relatively high TiO2 contents and are ferroan in nature. The geotechnical properties such as unconfined compressive strength (32702psi-34965psi), unconfined tensile strength (485psi - 535psi), specific gravity (3.109 and 3.169), water absorption (0.14% - 0.61%), loss Angeles abrasion (17.34% -17.36%), soundness (13.86 - 14.31), and flexural test values (30.065 N/mm2 - 30.066 N/mm2) show their suitability for construction work as aggregate for concrete and light foundation loads as well as indoor and outdoor dimension stones. The strength properties of all the studied samples have inverse ratio with the plagioclase content which is more probably due to perfect cleavage pattern of the plagioclase. The samples from Jodan Khatta show a relatively small grain size and fractured nature and demonstrate slightly weak mechanical properties as compared to Maira Chanser dolerite. Similarly, the Jodan Khatta samples show more alteration along their grain boundaries which have also affected their grain to grain relationship and thus have lower down their strength values. Moreover, their relatively fine-grained nature has also contributed to higher extent of alteration. The study confirms that mineralogical and textural variations have an important control on mechanical properties of the studied rocks.
References
Bailey, D. K., 1983. The chemical and thermal evolution of rifts, Tectonophysics, 94, 585-597.
Bell, F. G., 2007. Engeneering Geology. 2nd Edition, an Imprint of Elsevier, Butterworth-Heinemann.
Blyth, F. G. H., De Freitas, M. H., 1974. A Geology of Engineers. ELBS and Edward Arnold, London, 514.
Borner, K., Hill, D., 2010. Große Enzyklopa die der Steine: Die Naturstein-Datenbank. CD-ROM. Abraxas Verlag GmbH.
Brattli, B., 1992. The influence of geological factors on the mechanical properties of basic igneous rocks used as road surface aggregates. Engineering Geology. 33, 31-44.
Calkins, J. A., Offield, T. W., Abdullah, S., Ali, S. T., 1975. Geology of the southern Himalaya in Hazara, Pakistan, and adjacent areas, The United States Government Publishing Office, 2330-7102.
Cox, K. G., Pankhurst, R. J., 1979. The interpretation of Igneous Rocks: London, Allen & Unwin 450.
Gansser, A., 1980. The significance of the Himalayan suture zone. Tectonophysics, 62, 37–52.
Gunsallus, K. L., Kulhawy, F. H., 1984. A comparative evaluation of rock strength measures. International journal of rock mechanics and mining sciences, Geological Society of America, New York, 223–289.
Irfan, T., 1996. Minerology, fabric properties and classification of weathered granites in Hong Kong. Quarterly Journal of Engineering Geology and Hydrogeology, 29(1), 5-35.
Irvine, G. J., Baragar, W. R., 1971. A guide to the chemical classification of common volcanic rocks. Canadian Journal of Earth Sciences, 8, 523-548.
Kempe, D. R., Jan, M. Q., 1970. An alkaline igneous province in the North-West Frontier province, West Pakistan. Geological Magazine, 107(04), 395-398.
Le Bas., Mian, M. J. I., Rex, D. C., 1987. Age and nature of carbonatite emplacement in North Pakistan. International Journal of Earth Sciences, 76, 317-323.
Le Maitre, R. W., 2002. Igneous rocks: a classification and glossary of terms, 2nd edition. Cambridge University Press.
Lindqvist, J. E., Åkesson, U., Malaga, K., 2007. Microstructure and functional properties of rock materials. Materials Characterization, 58, 1183–1188.
Majid, M., Danishwar, S., Hamidullah, S., 1991. Petrographic and chemical variations in the rift-related basic dykes of the Malka Area (Lower Swat), NWFP, Pakistan. Geological Bulletin, University of Peshawar, 24, 1-23.
Olsson, W. A., 1974. Grain size dependence of yield stress in marble. Journal of Geophysical Research, 79(32), 4859-4861.
Pogue, K. R., Wardllaw B. R., Harris, A. G, Hussain, A., 1992. Paleozoic and Mesozoic stratigraphy of the Peshawar Basin, Pakistan correlation and implications. Bulletin of the Geological Society of America, 104, 915-927.
Rafiq, M., Jan, M. Q.,1988. Petrography of Ambela granitic complex, NW Pakistan, Geological Bulletin, University of Peshawar, 21, 27-48.
Sajid, M., Arif, M., Muhammad, N., 2009. Petrographic characteristics and mechanical properties of rocks from Khagram-Razagram area, Lower Dir, NWFP, Pakistan. Journal of Himalayan Earth Sciences, 42, 25-36.
Sajid, M., Coggan, J., Arif, M., Andersen, J., Rollinson, G., 2016. Petrographic features as an effective indicator for the variation in strength of granites. Engineering Geology, doi:10.1016/j.enggeo, 2016.01.001.
Sajid, M., 2012. Petrography, geochemistry and mechanical properties of igneous rocks from the Utla area of Gadoon, NW Pakistan. Unpublished thesis University of Peshawar, Pakistan.
Shams, F., Ahmed, Z., 1968. Petrology of the basic minor intrusives of the Mansehra-~ mb state area, N. West Pakistan, part I, the dolerite. Geological Bulletin University of Punjab, 7, 45-56.
Shand, S. J., 1943. Eruptive Rocks, 2nd Edition, John Wiley.
Treloar, P. J., Rex, D. C., 1990. Cooling and uplift histories of the crystalline thrust stack of the Indian plate internal zones west of Nanga Parbat, Pakistan Himalaya. Tectonophysics, 180, (2-4), 323-349.
Tugrul, A, Zarif, I. H., 1999. Correlation of mineralogical and textural characteristics with engineering properties of selected granitic rocks from Turkey, Engineering Geology, 51, 303-317.
Wilson, M., 1989. Igneous petrogenesis, A global tectonic approach. London, Boston, Sydney, Wellington: Unwin Hyman.
