Comparative study of weathering signatures in felsic igneous rocks of Hong Kong

Duzgoren-Aydin, Nurdan S.

doi:10.3184/095422902782775371

Cited by 8 publications

(7 citation statements)

References 6 publications

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“…In Hong Kong, halloysite to kaolinite ratios of samples from granitic profiles are larger than those of the samples from pyroclastic ones at the same degree of weathering. This has been attributed to better leaching conditions in granitic profiles than those of the pyroclastic profiles (Duzgoren- Aydin, 2003). Thus probability and mode of occurrence of critical heterogeneities in granitic and pyroclastic profiles are likely to be different as confirmed by the landslide investigations.…”

Section: Clay Mineralogymentioning

confidence: 86%

“…Thus, while absolute abundance of quartz remains almost constant, its relative abundance continuously increases as other primary minerals (feldspar and biotite) are gradually decomposed during the course of weathering. On the contrary, absolute abundances of clay minerals and oxyhydroxides increase with the degree of weathering (Duzgoren-Aydin, 2003).…”

Section: Parent-normalized Variation Diagramsmentioning

confidence: 95%

“…It has been documented that oxyhydroxide-rich zones are more frequent in pyroclastic profiles compared to granitic profiles. This becomes particularly evident at the advance stages of the weathering (Duzgoren-Aydin, 2003).…”

Section: Oxyhydroxidesmentioning

confidence: 98%

“…Recent studies on clay minerals within weathered igneous profiles (e.g., Merriman and Kempt, 1995;Merriman et al, 1996;Kirk et al, 1997;Duzgoren-Aydin et al, 2002b;Duzgoren-Aydin, 2003;Wen et al, 2004) in Hong Kong revealed that understanding the type and abundance of clay minerals and their distribution within weathered profiles are necessary to:…”

Section: Clay Mineralogymentioning

confidence: 99%

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Chemical and mineralogical heterogeneities of weathered igneous profiles: implications for landslide investigations

Duzgoren-Aydin

Aydın

2006

Nat. Hazards Earth Syst. Sci.

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Abstract. Landslides in tropical and sub-tropical regions are generally associated with weathered rock profiles which often possess chemical and mineralogical heterogeneities at material-and mineral-scales. Such heterogeneities reach a climax by the occurrences of oxyhydroxide-and clayrich zones. Weakness and low permeability of these zones makes them ideal for the development of slip zones along which landslides take place. This paper describes the nature and distribution of chemical and mineralogical heterogeneities within weathered profiles developed from felsic igneous rocks in Hong Kong. It sets out the use of integrated geochemical and mineralogical studies to improve understanding of the development of critical heterogeneities and hence to predict their types and presence in a given weathered profile.

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Section: Clay Mineralogymentioning

confidence: 86%

Section: Parent-normalized Variation Diagramsmentioning

confidence: 95%

Section: Oxyhydroxidesmentioning

confidence: 98%

Section: Clay Mineralogymentioning

confidence: 99%

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Chemical and mineralogical heterogeneities of weathered igneous profiles: implications for landslide investigations

Duzgoren-Aydin

Aydın

2006

Nat. Hazards Earth Syst. Sci.

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“…The depth of the granitic profile (.20 m) is deeper than that of the pyroclastic profile (;10 m). Field, mineralogical, and petrographical characteristics of the profiles (Duzgoren- Aydin, 2003) are summarized in Table 2.…”

Section: Study Areasmentioning

confidence: 99%

Chemical Heterogeneities of Weathered IgneousProfiles: Implications for Chemical Indices

Duzgoren-Aydin¹

2003

Environmental and Engineering Geoscience

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This study investigates the behavior of chemical elements and the performance of chemical indices within and between weathered pyroclastic and granitic profiles. The profiles were developed under humid, relatively well-drained conditions in Hong Kong. Levels of chemical heterogeneity of the profiles are assessed, and their adverse effects on the selection and use of chemical indices are discussed. Distribution of the chemical elements varies significantly within and between the profiles. At the early stages of weathering, behavior of the elements is fairly predictable and largely controlled by the degree of weathering. At the advanced stages, however, behavior of the elements can be erratic and appears to be governed by micro-environmental conditions and the degree of weathering. Based on the nature of the chemical elements displaying unpredictable distribution along the weathered profiles, two groups of elements are identified. The first group includes K and Al together with loss-on-ignition content. Their variation can be explained in terms of the type and abundance of clay minerals. The second group comprises Fe and Mn, and their unexpected behavior can be correlated with the irregular distribution of sesquioxide-rich zones. Micro-environmental conditions, which govern the type and abundance of clay minerals and sesquioxides, ultimately determine the level of chemical heterogeneity of the profiles. Parent-normalized major element variation diagrams are useful tools for assessing the level of chemical heterogeneity of the profiles. Overall, the pyroclastic profile displays a higher level of heterogeneity than the granitic profile. Performances of chemical indices are particularly poor where a high level of chemical heterogeneity exists. Similarly, chemical indices based on the elements displaying similar geochemical behavior or the degree of decomposition of a single mineral (e.g., plagioclase) will not remain valid over the entire course of weathering. Given that each profile has its own way of responding to weathering processes, the search for a universally accepted`best chemical index' is likely to disappoint. Recognizing the significance of the processes and products of weathering in controlling behavior of the chemical elements, however, and thus in generating chemical heterogeneities helps to avoid random or subjective selection of chemical indices and to interpret unforeseen deviations.

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Cadmium and Zinc in Mar Chiquita Coastal Lagoon (Argentina): Salinity Effects on Lethal Toxicity in Juveniles of the Burrowing Crab Chasmagnathus granulatus

Beltrame

Marco

Marcovecchio

2007

Arch Environ Contam Toxicol

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The large Argentine marine littoral zone is characterized by great number of wetlands and includes only one coastal lagoon, Mar Chiquita, which has been declared as a Biosphere Reserve by the Man and Biosphere Reserve Program from UNESCO. Its margins present populations of Chasmagnathus granulatus, a semiterrestrial crab distributed along wide salinity gradients that plays an important role as a key species within the corresponding trophic web. Dissolved cadmium (Cd) and zinc (Zn) concentrations present in this ecosystem were determined. Cadmium concentrations ranged between n.d. and 0.82 mug/L and zinc levels ranged between n.d. and 1224.38 mug/L within the mentioned coastal lagoon. Cd and Zn acute semistatic toxicity bioassays were carried out for 96 h on juvenile crabs of C. granulatus. LC(50) 96-h values were 2.24 mg Cd(2+)/L and 7.07 mg Zn(2+)/L at 5 psu, and 15.42 mg Cd(2+)/L and 11.41 mg Zn(2+)/L at 25 psu. Higher salinities resulted in lower metal toxicity. This effect was stronger for Cd than for Zn. C. granulatus juveniles LC(50) 96-h values determined for Cd were three to four orders of magnitude higher than the corresponding dissolved metal concentrations in the Mar Chiquita coastal lagoon; nevertheless, those Zn values determined were similar to several ones corresponding to natural water samples.

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Comparative study of weathering signatures in felsic igneous rocks of Hong Kong

Cited by 8 publications

References 6 publications

Chemical and mineralogical heterogeneities of weathered igneous profiles: implications for landslide investigations

Chemical and mineralogical heterogeneities of weathered igneous profiles: implications for landslide investigations

Chemical Heterogeneities of Weathered IgneousProfiles: Implications for Chemical Indices

Cadmium and Zinc in Mar Chiquita Coastal Lagoon (Argentina): Salinity Effects on Lethal Toxicity in Juveniles of the Burrowing Crab Chasmagnathus granulatus

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