Overturned folds, superposed thrusts and structural overprints near Sungai Buah, Selangor

702001-101149-954-B
Author : Zaiton Harun and H.D. Tjia
Publication : Bulletin of the Geological Society of Malaysia
Page : 225-236
Volume Number : 17
Year : 1984
DOI : https://doi.org/10.7186/bgsm17198411

Bulletin of the Geological Society of Malaysia, Volume 17, Dec.1984, pp. 225 – 236

 

Overturned folds, superposed thrusts and structural overprints near Sungai Buah, Selangor

ZAITON HARUN & H.D. TJlA

Jabalan Geologi, Universiti Kebangsaan Malaysia, Bangi

 

Abstrak: Berhampiran dengan sempadan Selangor-Negeri Sembilan di Kampung Sungai Buah, terdapat lapisan batu pasir metamorf berfoliasi dan filit (1) membentuk lipatan-lipatan terbalik yang besar beramplitud sekitar 25 m dengan satah paksi berkemiringan sederhana hingga landai;(2) yang tersungkup ke arah barat di sepanjang sesar-sesar songsang yang bersudut kecil, di samping sungkupan ke arah tenggara yang menindan arah pertama; (3) mempamerkan foliasi tersendeng curam memotong foliasi berkemiringan landai, jurus kedua-duanya adalah serupa; (4) menunjukkan perhubungan yang tidak lazim di antara ira yang berkemiringan lebih curam daripada perlapisan dalam satu lapisan nipis yang terbalik. Kebanyakan struktur mencadangkan adanya canggaan polifasa. Dari segi litologi, batuan ini mempunyai keserupaan batuan Bukit Kenny di kawasan Kuala Lumpur. Oleh itu, canggaannya besar kemungkinan berlaku semasa Trias-Awal Jura. Selain dari kemungkinan canggaan polifasa, penyungkupan bertindan juga ditafsirkan sebagai hasil dari penyungkupan umum ke barat, sementara penyungkupan ke arah tenggara di anggap sebagai penyungkupan berlawanan secara tempatan.

 

Abstract: In the vicinity of the Selangor-Negeri Sembilan border at Kampung Sungai Buah are folialed metasandstone and phyllite (1) forming large: overturned folds with moderately to gently dipping axial planes and ampliltudes in the order of 25 m: (2) that were: thrusted along low-angle reverse faults towards west and also superposed on this direction thrusted towards southeast; (3) exhibiltng steeply inclined foliation transecting gentler dipping foliation, both having similar strikes; (4) showing anomalous relation of cleavage dipping steeper than bedding in an overturned layer. Polyphase deformation is suggested by most of the structures. Lithologically, the rocks are similar to Kenny Hill rocks of the Kuala Lumpur area. Therefore, the deformation very probably occurred in Triassic-Early Jurassic time. In spite of the probability of polyphase deformation, yet the superposed thrusts are interpreted as being products of general thrust westward, while the southeasterly directed thrust is considered as localized “backward thrusting". 

https://doi.org/10.7186/bgsm17198411