Weathering mechanisms and indices of the igneous rocks of Hong Kong

	Weathering mechanisms and indices of the igneous rocks of Hong Kong
	Ng, CWW ; Guan, P ; Shang, YJ
刊名	QUARTERLY JOURNAL OF ENGINEERING GEOLOGY AND HYDROGEOLOGY
	2001-05-01
卷号	34 页码:133-151
关键词	geochemistry geomaterials igneous rock laboratory tests weathering
ISSN号	0481-2085
文献子类	Article
英文摘要	Weathering mechanisms of volcanic and granitic rocks in Hong Kong have been studied by chemical analysis, optical microscopy on thin sections and magnetic susceptibility measurements. The mobility of elements of calcium, sodium, iron, potassium, magnesium, silicon, aluminium and constitutional water is investigated in detail using the Mobility Index. Chemical weathering processes in Hong Kong are dominated by decomposition of feldspars and biotite, leaching of alkali and alkaline earth metals, and enrichment of ferric oxide under prolonged subtropical climate conditions. Data for some granitic residual soils from five neighbouring regions in Southern China are also gathered and examined. It is found that the residual soils in Hong Kong are abnormal and immature with respect to its latitude. By examining various quantitative chemical indices and comparing them with the current six-grade material classification scheme, WPI, LOI and I-mob are found to be good indicators of the degree of weathering for both volcanic and granitic rocks in Hong Kong. Regarding the optical microscopy, the micropetrographic index (I-p) is only suitable for granitic rock but not for Volcanic rock due to the presence of fine-grained minerals and small voids. For the magnetic susceptibility measurements, consistent results with weathering grades for volcanic rocks are obtained by applying a moving average technique. However, due to the low content of Al2O3 and Fe2O3 in granitic rock, SOC and the magnetic susceptibility index, which are appropriate for quantifying the degree of weathering of volcanic rock, are not quite suitable for the granitic rock.
WOS关键词	GEOCHEMISTRY
WOS研究方向	Engineering ; Geology
语种	英语
出版者	GEOLOGICAL SOC PUBL HOUSE
WOS记录号	WOS:000168500800001
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/77093]
专题	中国科学院地质与地球物理研究所
通讯作者	Ng, CWW
作者单位	1.Hong Kong Univ Sci & Technol, Dept Civil Engn, Kowloon, Hong Kong, Peoples R China 2.Beijing Univ, Dept Geol, Beijing 100871, Peoples R China 3.Chinese Acad Sci, Inst Geol, Beijing 100029, Peoples R China
推荐引用方式 GB/T 7714	Ng, CWW,Guan, P,Shang, YJ. Weathering mechanisms and indices of the igneous rocks of Hong Kong[J]. QUARTERLY JOURNAL OF ENGINEERING GEOLOGY AND HYDROGEOLOGY,2001,34:133-151.
APA	Ng, CWW,Guan, P,&Shang, YJ.(2001).Weathering mechanisms and indices of the igneous rocks of Hong Kong.QUARTERLY JOURNAL OF ENGINEERING GEOLOGY AND HYDROGEOLOGY,34,133-151.
MLA	Ng, CWW,et al."Weathering mechanisms and indices of the igneous rocks of Hong Kong".QUARTERLY JOURNAL OF ENGINEERING GEOLOGY AND HYDROGEOLOGY 34(2001):133-151.