Honeycomb Weathering of Limestone Building on The Archaeological Sites on Leptis Magna (Libya): Causes, Processes and Damages.

نوع المستند : المقالة الأصلية

المؤلف

conservation department faculty of archaeology south valley university(Egypt)

المستخلص

Honeycomb weathering is a common surface phenomenon affecting a variety of rocks in a range of environments. The processes involve the progressive of closely spaced cavities which are generally small with an average width few millimeters to several centimeters in diameter. Honeycomb weathering, also known as fretting, cavernous weathering, alveoli/alveolar weathering, stone lattice, stone lace or miniature tafoni weathering. Incipient honeycomb weathering in a homogeneous limestone has been experimentally reproduced by wind exposure and salt crystallization. It is a type of salt weathering common on coastal and semi-arid limestone. Honeycomb weathering occurs in many populated region and must have been noted in archaeological sites at Leptis Magna (Libya). Leptis Magna is a World Heritage site on the Mediterranean coast of North Africa in the Tripolitania region of Libya. In order to create an appropriated conservation concept, it was necessary to investigate the damage processes. For this purpose, X-ray powder diffraction (XRD), optical and scanning electron microscope (SEM) attached with EDX, Stereo microscope, polarizing microscopes (PM) were used. Bio-deterioration problems in the site were analyzed taking into account their impact on the substrate and their relationship with environmental factors. Chemical analysis and field observations indicated that honeycomb weathering in coastal exposures of limestone at archaeological sites of the Leptis Magna results from evaporation of salt water deposited by wave splash from Mediterranean Sea. Microscopic examination of weathered samples show that erosion results from disaggregation of minerals grains rather than from chemical decomposition. Thin walls separating adjacent cavities seem to be due to protective effects of organic coatings produced by microscopic algae inhabiting the rock surface.

الموضوعات الرئيسية

المراجع

Auger F. (1987) Alteration des roches sous influence marine;
degradation des pierres en oeuvre et simulation acceleree en
laboratoir. These Doctorat d’Etat es Siences. Universite de
Poitiers, France.
 Bandineli, R. B., Caffarelli, E.V. and Caputo G.(1964) The
Buried City: Excavation at Leptis Magna,1st edition, Weidenfeld
and Nicolson, 1964
 Cardell C, Rivas T, Mosquera MJ, Birginie JM, Moropoulou A,
Prieto B, Silva B, Van Grieken R. (2002) Patterns of damage in
igneous and sedimentary rocks under conditions simulating seasalt weathering. Earth Surf Processes Landform, in press.
 Cardell C., Delalieux F., Roumpopoulo K., A. Moropoulou, F.
Augerc, Van Grieken, R. (2003)Salt-induced decay in calcareous
stone monuments and buildings in a marine environment in SW
France, Construction and Building Materials 17, pp.165–179
 De Freitas VP, Abrantes V, Crausse P. (1996) Moisture
migration in building walls. Analysis of the interface
phenomena. Build Environ; 31(2): pp.99 –108.
 Dorn RI. Digital (1995) Processing of backscatter electron
imagery: a microscopic approach to quantifying chemical
weathering. Geol Soc Am Bull;107:725 –41.
 Don Hallett,(2004) Petroleum geology of Libya, El-sevier ltd,
London , pp.252-254
 Dunham, R.J., (1962) Classification of carbonate rocks
according to deposition texture. In: HAM, W,F.(ed):Classification of carbonate rocks, Tulsa akla-Am. Assac. Petrol.
Geol. Publ., 1, pp. 108:121
 Fred G.B. (1999) Karst and cavernous rocks In Engineering And
Construction, M.G. Culshaw, Tony Waltham,
 Hume, W. F., (1925) Geology of Egypt, v.1, Surface features:
Cairo, Government press, pp. 214-216.
 Jain, K. K., A. K. Mishra, and Singh T. (1993) Biodeterioration
of stone: A review of mechanism involved. In Recent Advances
in Biodeterioration and Biodegradation, vol.1, Calcutta: Naya
Prokash, pp 323-354.
 Kumar, R., Anuradha V.K., (1999) Biodeterioration of stone in
tropical environments, Paul Getty trust, printed in the USA,.
 Mustoe, G. E. (2010) Biogenic origin of coastal honeycomb
weathering. Earth Surface Processes and Landforms, V.35, pp.
424:434.
 Mustoe, G. E., (1982) The Origin of Honeycomb Weathering,
Geological Society of America Bulletin, V. 93, pp. 108-115.
 Miller S., Mcgibbon F. M., Caldwell, D. H. & Ruckley N. A.,
(2006) Geological tools to interpret Scottish medieval carved
sculpture: combined petrological and magnetic susceptibility
analysis, Geomaterials in Cultural Heritage. Geological Society,
London, Special Publications, 257, pp.283-305.
 Mustoe, G. E. (1982) The Origin of Honeycomb Weathering,
Geological Society of America Bulletin,V. 93, pp. 108-115.
 Okafor N., Ejiofor M.A.N., (1985) The linamarase
of Leuconostoc mesenteroides, production, isolation and some
properties. J. Sci. Food Agric., 36:, pp 667-678.
 Raper K.B., Fennell D.I, The Genus Aspergillus, Baltimore:
Williams & Wilkins Company, 1965, pp 686
 Rotherham, F., Spode, F., Elbah, S., & Fraser, D., (2003) A
comparison of limestone quarries and their potential for
restoration and after –use in Libya and the UK., proceedings of
the 7th international conference of the international affiliation ofland reclamationists runcorn/United Kingdome/13-16 May,
pp.331-340.
 Rodriguez, C. N., Doehne E., Sebastian E., (1999), Origins of
honeycomb weathering: The role of salts and wind, GSA
Bulletin, V. 111, NO. 8, pp. 1250-1255.
 Rodriguez, C., Navarro, Doehne,E., and Sebastian,E.,( 1999)
Origins of honeycomb weathering, the role of salts and wind,
GSA Bulletin, V. 111, no. 8, pp. 1250-1255
 Saxena, V. K., K. K. Jain, and. Singh T.( 1991) Mechanisms of
biologically induced damage to stone materials. In
Biodeterioration of Cultural Property: Proceedings of the
International Conference on Biodeterioration of cultural
property, Held at national Research Laboratory for Conservation
of Cultural Property, in Collaboration with ICCROM and
INTACH. New Delhi: Macmillan India. Pp.249-258.
 Smith, B.J., Torok, A., McAlister, J.J. and Megarry, Y.(2003),
Observations on the factors influencing stability of building
stones following contour scaling: a case study of oolitic
limestone from Budapest, Hungary. Building and Environment،
n.38, pp.1173–1183.
 Young A.R.M (1987) Salt as an agent in the development of
cavernous weathering. Geology; 15:962 –6.

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