Pertanika 11(3), 375-384(1988)
Properties of Soils Derived from Some Metamorphic Rocks in Peninsular Malaysia S. ZAUYAH Department of Soil Science, Faculty of Agriculture, Universiti Pertanian Malaysia 43400 Serdang, Selangor, Malaysia. Key words: Soil properties; parent materials; pedofeatures ABSTRAK
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Sifat-sifat morfologi, fizik, kimia, mineralogi dan mikromorfologi ke atas limajenis tanahyang terbentuk daripada batuan metamorf (skis kuarza-mika, filit, skis serisit bergrafit, skis amfibol dan serpentinitj telah dikaji. Sifat-sifat ini didapati terpengaruh oleh jenis bahan induk. Tanah-tanih yang ter~ terbentuk daripada batuan yang rendah kandungan mineral senang luluhawa dan jumlah ferum rendah (skis kuarza-mika, filit, skis serisit) adalah berwarna kuning kemerahan, bertekstur lempung berkelodak, berstruktur blok serta mempunyai jumlah keupayaan pertukaran kation, ketepuan bes dan ferum oksida bebas yang rendah. Horizon diagnostik pada tanah ini ialah horizon argilik. Tanah-tanih yang terbentuk daripada batuan yang tinggi kandungan mineral senang luluhawa (skis amfibol dan serpentinit) adalah berwarna merah hingga coklatf bertekstur lempung, berstruktur gerintil, serta mempunyai jumlah keupayaan pertukaran kation rendah, ketepuan bes sederhana, kandungan ferum oksida bebas tinggi. Horizon diagnostik ialah oksik. Ciri-ciri pedo yang banyak terdapat dalam kumpulan tanah yangpertama ialah pengisian lempung dan kotoran manakala dalam kumpulan tanah yang kedua pengisisan kotoranlah yang banyak sekali.
ABSTRACT The morphological physical, chemical, mineralogical and micromorphological properties of five soils developed over some metamorphic rocks (quartz-mica schist, phyllite, graphitic sericite schist, amphibole schist and serpentinite) were examined. These properties were found to be influenced by the parent materials. Soils developed over rocks with low amounts of weatherable minerals (ferromagnesian) and low total iron content (quartz-mica schist, sericite schist and phyllite) are reddish yellow, have silty clay textures and blocky structures, low CEC and base saturation and low free iron oxide content. The diagnostic horizon is argillic. Soils formed over rocks with high amounts of weatherable minerals (amphibole schist and serpentinite) are red to brown, have clayey textures, granular structures, low CEC, moderate base saturation and high free iron oxide content The diagnostic horizon is oxic. Pedofeatures in the first group of soils are dominated by clay and excremental infillings whilst in the second group, only excremental infillings are dominant. INTRODUCTION Metamorphic rocks such as phyllite, sericite schist and quartz-mica schist are some of the common parent materials of soils mapped in Peninsular Malaysia. Although there have been many studies related to the genesis of soils in Malaysia (Eswaran
and Wong, 1977; Lim, 1977; Paramananthan, 1977; Loh, 1981; Zainol, 1984) the weathering of metamorphic rocks in relation to soil formation has received less attention than that of igneous and sedimentary rocks. Properties of soils developed on igneous rocks and sedimentary
S. ZAUYAH
6 0 km
; v.
\
P E N INSULAR M ALAYSIA
1
Sampling site of profile I.
Quartz-mica schist
2.
Graphitic sericlte schist
3.
Phyllite
4.
Amphibole schist
5.
Ssrpentinite
Fig. 1: Map of Peninsular Malaysia showing the locations of the profiles studied.
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PERTANIKA VOL. 11 NO. 3, 1988
PROPERTIES OF SOILS DERIVED FROM SOME METAMORPHIC ROCKS
rocks have been shown to be dependent on the lithology, and iron content of the rocks from which the soils are derived (Paramananthan, 1977, Zauyah, 1984). Studies on properties of soils derived from these parent rocks have provided more data for soil classification and soil survey interpretations. In this study, soils developed on five metamorphic rocks of different metamorphic grades and petrographic properties were examined. They are quartz-mica schist, phyllite, graphitic sericite schist, serpentinite and amphibole schist. The objective of this study is to examine the morphological, physical, chemical, mineralogical and micromorphological properties of these soils and relate these properties to the inherent properties of the parent materials. MATERIALS AND METHODS Materials
The five soil profiles sampled for the study are in different parts of the Peninsular Malaysia (Fig 1). The quartz-mica schist is situated in the north of Kuala Lumpur city and belongs to the Dinding Schist Formation of Lower Paleozoic. The graphitic sericite schist belongs to the Kajang Formation (predominantly of quartz sericite and graphitic sericite schists) which is of middle Upper Silurian age. It is located in the Universiti Pertanian Campus in Serdang. The phyllite outcrop is exposed 6 km from Karak town on the Kuala Lumpur-Karak Highway. It belongs to the Karak Formation which is of Lower Devonian age and consists predominantly of carbonaceous argillaceous rocks. Isolated bodies of amphibolites and serpentinites are found in several parts of Peninsular Malaysia. The serpentinite profile sampled is exposed on a roadcut of an ellipsoidal shaped intrusive body (about i.5 km long) with preCarboniferous quartz-mica schist on the Seremban -Kuala Pilah road. The amphibole schist profile sampled is a roadcut exposed along the Kuala Lumpur-Karak Highway near Bentong. It is a lenticular-shaped body (1 km long) occurring within a sequence of low—grade regionally metamorphosed schist of the Bentong Group.
Methods The soil profiles were examined and the morphological zones were first identified i.e. rock, saprock, saprolite, pedoplasmation zone and soil horizons. Field description of the soil horizons were done following the guidelines in the Soil Survey Manual (USDA, 1981) and FAO 'Guidelines for Soil Description' (1977). The horizons were then sampled by collecting about 2 kg for bulk analyses, clods for bulk density determinations and undisturbed samples in Kubiena boxes for thin sections. For the amphibole schist and the serpentinite profiles, samples were also collected close to and along the joint planes. The soil and weathered material were fractioned into clay (< 2 /xm), silt (2-50 jjm) and sand (50-200 jum) by successive sedimentation. The clays were deferrated following the method of Mehra and Jackson (1960). All the fractions were analysed for their mineralogical composition by X-ray diffraction. The routine chemical analyses carried out on the soil and some of the weathered samples are as follows: pH (1:2.5) in water, CEC and exchangeable bases (Chapman, 1965), extractable aluminium (Yuan, 1959) and extractable free iron (Mehra and Jackson, 1960), Thin sections (9 cm x 12 cm and 9 cm x 6 crn) were prepared by impregnating the samples with unsaturated polyester resin. The micromorphological features related to microstructure, coarse and fine fractions and pedofeatures were described according to the terminology of Bullock et al (1985). Fresh fracture surfaces of average size 4 mm were also examined with a Jeol 35C scanning electron microscope. Bulk density was determined by the method of Brasher (1966). The Atterberg Limits (plastic limit and liquid limit) were determined according to the BSI (1975) method of analyses. COLE values were calculated from the bulk densities of the moist soil and oven dried soil as outlined by Grossman et al (1968). RESULTS AND DISCUSSION
Morphological Properties The morphological properties of the soils studied are summarised in Table 1. From these properties
PERTANIKA VOL. 11 NO. 3, 1988
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S. ZAUYAH TABLE 1 Morphological properties of the B horizons of soils developed on some metamorphic rocks in Peninsular Malaysia. * ^ ^
Parent Phyllite
Graphitic Sericite Schist
Quartz-Mica Schist
Amphibole Schist
Serpentinite
Properties ^ ^ ^ ^ Subsoil Texture Diagnostic Horizon
Silty clay
Silty clay
Silty clay
Clay
Clay
Argillic
Argillic
Argillic
Oxic
Oxic
Reddish yellow 7.5 YR 6/8
Reddish yellow 7.5YR 6/6
Reddish yellow 7.5YR 6/8
Yellowish red 5YR 5/6
Dark reddish brown 5YR 3/3
Subangular blocky
Subangular blocky
Granular
Granular
Friable
Friable
Colour Pale brown 10YR 7/4 Structure
Consistency
Angular blocky Firm
Firm
Drainage
Moderately well drained
Well drained
Depth of Solum
Moderately deep
Moderately deep
two distinct groups of soils can be identified:those that developed over the first three parent rocks i.e. quartz-mica schist, phyllite and graphitic sericite and those over the amphibole schist and the serpentinite. The former group corresponds to rocks i.e. quartz-mica schist, phyllite and graphitic sericite schist and those over the amphibole schist and the serpentinite. The former gropp corresponds to rocks with low weatherable minerals (mainly quartz and mica) whilst the latter group has high weatherable minerals (serpentine, actinolite, epidote). In the field too, these two groups show differences in their profile morphology. The soils developed over rocks low in weatherable minerals or silica rich, have horizons which are easily distinguished in the field. They show characteristics of argillic horizons. On the other hand, soils developed over rocks high in weatherable minerals have almost indistinct horizonation and are oxic in characteristics. Other distinctintive properties of the first group of soils are : reddish yellow colours, silty clay textures, firm consistency, subangular to blocky structures and are well drained. 378
Firm Well drained
Deep
Well drained
Deep
Excessively drained Deep
The second group of soils (over serperitinite and amphibole schist) are deep, well drained to excessively drained profiles, are red to brown, have clayey textures and friable consistency. Paramananthan (1977) also noted that soils developed over parent materials high in weatherable minerals show an increase in sesquioxides which resulted in the formation of microaggregates thereby increasing the porosity. As such these soils are freely drained and lacking in features which can be used to differentiate the horizons. Chemical Properties The chemical properties of the soils are given in Table 2. The soils can be similarly grouped into those that formed on parent rocks low in weatherable minerals and total iron content (phyllite, graphitic sericite schist and quartz-mica schist) and those that formed over amphibole and serpentinite. The first group of soils show almost similar chemical properties: low pH, low CEC and base saturation, high aluminium saturation and low free iron content (by dithionite extraction).
PERTANIKA VOL. 11 NO. 3, 1988
PROPERTIES OF SOILS DERIVED FROM SOME METAMORPHIC ROCKS TABLE 2 Chemical and physical properties and mineralogy of the B horizons of soils developed on some metamorphic rocks in Peninsular Malaysia.
^•N.
Parent
SoU Nv Properties ^ " s .
CHEMICAL
pH (H2O) Charge Characteristics (c mol (+)/kg soil
Amphibole Schist
4.5
4.9
CEC < 12.5
CEC > 16
CEC < 1 6
ECEC
ECEC < 5
Al Saturation (ECEC basis)
>85%
70%
3.4-4.1%
3.4-4.9%
10.6-15.6%
16.8-19.6%
Quartz
Quartz
Quartz
Quartz
Quartz
Silt
Quartz Kaolinite Muscovite
Quartz Kaolinite Muscovite
Quartz, Kaolinite Mica-smectite
Gibbsite Goethite Kaolinite
Gibbsite Kaolinite Goethite
Clay
Kaolinite Quartz Muscovite
Kaolinite Quartz Muscovite
Kaolinite, MicaSmectite, Quartz
Kaolinite Goethite
Kaolinite Goethite
1.55-1.69
1.40-1.54
1.27-1.35
11-14
13
O
fi
MINE
4.3
Quartz-Mica Schist
ECEC < 12.5
< 10%
Sand
KYSIC
4.5
Base Saturation
Free iron oxide (dithionite)
