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“Plagioclase solution degree index”: a new index to evaluate the weathering degree of granite

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The weathering degree of rocks has an adverse influence on their strength and deformability characteristics, which in turn influences the industrial uses of rock. The need to develop a weathering index that reveals their mechanical and engineering geological behaviors is thus pertinent to enable the building of more accurate models for forecasting geological hazards. Granite weathering in the Ma On San, Shek Kip Mei and Kwun Tong areas of Hong Kong was studied using scan electron microscope (SEM) images to observe mineral shapes for detailed identification of the weathering degree of completely decomposed granite (CDG). Plagioclase images captured from the SEM were subsequently analyzed and processed with the use of a microstructural image processing system. The results of the analyses indicate that plagioclase, though sensitive to weathering, still remains in CDG and is preserved at different weathering degrees. Hence, it provides a possibility for evaluating the weathering degree more accurately. Thus, a new index referred to as the plagioclase solution degree index is proposed to evaluate the weathering degree of granite.

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  • Apollaro C, Accornero M, Marini L, Barca D, De Rosa R (2009) The impact of dolomite and plagioclase weathering on the chemistry of shallow groundwaters circulating in a granodiorite-dominated catchment of the Sila Massif (Calabria, Southern Italy). Appl Geochem 24:957–979

    Article  Google Scholar 

  • Best MG (2003) Igneous and metamorphic petrology. Oxford Blackwell Science, Malden, MA, p 729

    Google Scholar 

  • Ceryan S (2008) New chemical weathering indices for estimating engineering properties of rocks: a case study from Kürtün Granodiorite NE Turkey. Turk J Earth Sci 17:187–207

    Google Scholar 

  • Ceryan S (2012) Weathering indices for assessment of weathering effect and classification of weathered rocks: a case study from NE Turkey, earth sciences, Dar IA (ed), ISBN: 978-953-307-861-8, InTech, available from:

  • Ceryan S, Tudes S, Ceryan N (2008) A new quantitative weathering classification for igneous rocks. Environ Geol 55:1319–1336

    Article  Google Scholar 

  • Clarke DB (1992) Granitoid rocks. Chapman and Hall, London, p 283

    Google Scholar 

  • Dearman WR (1984) State of weathering. The search for a rational approach. Site investigation practice: assessing BS 5930. In Hawkins AB (ed). Geological Society Engineering Geology Special Publication

  • Dearman WR, Turk N, Irfan TY, Rowshanei H (1987) Detection of rock material variation by sonic velocity zoning. Bull Int Assoc Eng Geol 35:3–8

    Article  Google Scholar 

  • Gillott JE (1968) Clay in engineering geology. Elsevier, Amsterdam

    Google Scholar 

  • Gokceoglu C, Zorlu K, Ceryan S, Nefeslioglu HA (2009) A comparative study on indirect determination of degree of weathering of granites from some physical and strength parameters by two soft computing techniques. J Mater Charact 60:1317–1327

    Article  Google Scholar 

  • Gupta AS, Rao KS (2001) Weathering indices and their applicability for crystalline rocks. Bull Eng Geol Environ 60:201–221

    Article  Google Scholar 

  • Haralick RM (1979) Statistical and structural approaches to texture. Proc IEEE 67:786–804

    Article  Google Scholar 

  • Harnois L, Moor JM (1988) Geochemistry and origin of the Ore Chimney Formation, a transported paleoregolith in the Grenville Province of Southern Ontario, Canada. Chem Geol 69:267–289

    Article  Google Scholar 

  • Hu RL (1995) Quantitative model and engineering geologic characteristics of microstructures of viscous soil. Geological Publishing House, Beijing (in Chinese)

    Google Scholar 

  • Hu RL, Yue ZQ, Tham LG, Wang LC (2005) Digital image analysis of dynamic compaction effects on clay fills. J Geotech Geoenviron Eng 131:1411–1422

    Article  Google Scholar 

  • Huang Z (1996) The red weathering crest in southward of China. China Ocean Press, Beijing (in Chinese)

    Google Scholar 

  • Huang Z (1998) Application of SPT in eluvial soil of granite. Mod Surv 3:2–19 (in Chinese)

    Google Scholar 

  • Irfan TY (1994) Mineralogy and fabric characterization and classification of weathered granitic rocks in Hong Kong. GEO report No.41, GEO, Civil Engineering Department, Hong Kong

  • Kamei A, Fukushi K, Takagi T, Tsukamoto H (2012) Chemical overprinting of magmatism by weathering: a practical method for evaluating the degree of chemical weathering of granitoids. Appl Geochem 27(3):796–805

    Article  Google Scholar 

  • Lumb P, Lee CF (1975) Clay mineralogy of the Hong Kong soils. Proceedings of the Fourth Southeast Asian Conference on Soil Engineering, Kuala Lumpur, pp 41–50

    Google Scholar 

  • Marques EAG, Barroso EV et al (2010) Weathering zones on metamorphic rocks from Rio de Janeiro—Physical, mineralogical and geomechanical characterization. Eng Geol 111(1–4):1–18

    Article  Google Scholar 

  • Read G, Rob AK, James R (1996) Development of a feldspar weathering index and its application to a buried soil chronosequence in southeastern England. Geoderma 74(3–4):267–280

    Article  Google Scholar 

  • Reiche P (1943) Graphic representation of chemical weathering. J Sediment Petrol 13:58–68

    Google Scholar 

  • Rigopoulos I, Tsikouras B, Pomonis P, Hatzipanagiotou K (2010) The influence of alteration on the engineering properties of dolerites: the examples from the Pindos and Vourinos ophiolites (northern Greece). Int J Rock Mech Min Sci 47:69–80

    Article  Google Scholar 

  • Ruxton BP (1968) Measures of the degree of chemical weathering of rocks. J Geol 76:518–527

    Article  Google Scholar 

  • Schiavon N (2007) Kaolinisation of granite in an urban environment. Environ Geol 52(2):399–407

    Article  Google Scholar 

  • Smart P, Tovey NK (1988) Theoretical aspects of intensity gradient analysis. Scanning 8:75–90

    Google Scholar 

  • Tuğrul A, Gurpınar O (1997) The effect of chemical weathering on the engineering properties of Eocene basalts in northeastern Turkey. Environ Eng Geosci 3:225–234

    Google Scholar 

  • White AF, Bullen TD, Schulz MS, Blum AE, Huntington TG, Peters NE (2001) Differential rates of feldspar weathering in granitic regoliths. Geochim Cosmochim Acta 65:847–869

    Article  Google Scholar 

  • Xiang G (1987) Point loading test—an express method to study the weathering zone of rock. J Chengdu Coll Geol 2:2–145 (in Chinese)

    Google Scholar 

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The research reported in this paper was supported by the National Natural Science Foundation of China (No. 41330643, No. 41072226 and No. 41030750).

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Correspondence to Ibrahim A. Oyediran.

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Hu, R., Oyediran, I.A., Gao, W. et al. “Plagioclase solution degree index”: a new index to evaluate the weathering degree of granite. Bull Eng Geol Environ 73, 589–594 (2014).

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