Komposisi unsur surih dan major di sepanjang profil luluhawa syal Formasi Mahang di Sungai Merbok, Kedah


Author : Habibah Hj Jamil & Wan Fuad Bin Wan HassanPublication : Bulletin of the Geological Society of MalaysiaVolume : 45Page : 59-64Year : 2002


Description

Bulletin of the Geological Society of Malaysia, Volume 45, May 2002, pp. 59 - 64

 

Komposisi unsur surih dan major di sepanjang profil luluhawa syal Formasi Mahang di Sungai Merbok, Kedah

Habibah Hj Jamil and Wan Fuad bin Wan Hassan

Program Geologi, Pusat Sains Sekitaran dan Sumber Alam, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor

 

Abstrak: Sebahagian besar daripada kawasan Sungai Merbok, Kedah terdiri daripada batuan Formasi Mahang. Unit batuannya terdiri daripada syal, sabak merah, sabak kelabu dan sabak hitam. Kajian mengenai taburan unsur-unsur surih dan major terhadap syal yang mengalami luluhawa telah dijalankan. Sampel profil luluhawa telah diambil pada potongan bukit di Ladang United Pillai. Komposisi unsur surih dan major di sepanjang profil luluhawa ditentukan menggunakan kaedah pendarfluor sinar-X (XRF). Unsur-unsur major dan surih mengalami pengkayaan dan pengurangan yang ketara pada dua kedalaman iaitu di sempadan tanih-Iempung bersifat batuan (350 cm) dan lempung bersifat batuan-batuan segar (770-870 cm). SiO2, K2O dan MgO mengalami pengurangan di kedalaman 350 cm dan 770 cm manakala Fe2O3, AI2O3, TiO2, Na2O, P2O, CaO dan MnO mengalami pengkayaan. Ba, Ce dan Pb mengalami pengkayaan pada kedalaman 350 cm dan 870 cm. Cr dan Cu mengalami pengkayaan di kedalaman 350 cm. Zn meningkat mengikut kedalaman di sepanjang lapisan tanih. Ia berkurang secara mendadak pada kedalaman 350 cm. Kemudian, ia meningkat semula mengikut kedalaman profil. Ba, Ce, Cu dan Zn kaya di dalam reranting dan nodul Mn oksida. Pb tidak berubah manakala Cr tidak dikesan. Komposisi unsur major dan surih di sepanjang profil syal bergantung kepada ketahanan dan mobiliti unsur tersebut di sepanjang profil luluhawa. Aktiviti larut resap yang tinggi di kawasan ini menyebabkan unsur-unsur terlarut di permukaan profil dan berkumpul pada kedalaman tertentu di dalam profil.

 

Abstract: Most of the Sungai Merbok area, Kedah is underlain by the Mahang Formation. The rock unit comprises shale, red slate, grey slate and black slate. A study of major and trace elements composition in weathered shale has been carried out. Samples of weathering shale profile were taken from a hill-cut at Ladang United Pillai. Composition of major and trace elements along the weathering profile was determined by X-ray fluorescence method (XRF). The major and trace elements increased or depleted significantly at two depths i.e. at the boundaries of the soil-hard clay (350 cm) and the hard clay-fresh rock (770-870 cm). SiO2, K2O and MgO depleted at 350 cm and 770 cm depth whereas Fe2O3, AI2O3, TiO2, Na2O, P2O, CaO and MnO increased. Ba, Ce and Pb increased at 350 cm and 870 cm depth. Cr and Cu increased at 350 cm depth. Zn increased gradually towards the bottom of the soil layers. The concentrations decreased abruptly at 350 cm depth. Then, it increased gradually towards the bottom of the profile. Ba, Ce, Cu and Zn were enriched in dendritic Mn oxides and nodules. Pb remained constant whereas Cr was not detected. The compositions of major and trace elements in shale profile depend on their resistivity and mobility along the weathering profile. The high leaching activity in this area causes the elements to dissolve at the surface, followed by accumulation at certain depth in the weathering profile.

https://doi.org/10.7186/bgsm45200209