Struktur dan canggaan Lapisan Mersing di Teluk Bangka, Mersing, Johor


Author : Harminzar Mansor, Ibrahim Abdullah, Azirul Liana Abdullah, Jatmika Setiawan & Mohd Syukri WahidPublication : Bulletin of the Geological Society of MalaysiaVolume : 49Page : 85-92Year : 2004


Description

Bulletin of the Geological Society of Malaysia, Volume 49, April 2004, pp. 85 - 92

 

Struktur dan canggaan Lapisan Mersing di Teluk Bangka, Mersing, Johor

HARMINZAR MANSOR, IBRAHIM ABDULLAH, AZIRUL LIANA ABDULLAH, JATMIKA SETIAWAN & MOHD SYUKRI WAHID

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

 

Abstrak: Kawasan kajian tertumpu di sepanjang bahagian barat Teluk Bangka, Mersing yang terdiri daripada singkapan pantai. Litologi yang dicerap di kawasan ini terdiri dari metakuarzit, filit dan selang lapis antara metakuarzit dan filit yang dikenali sebagai Lapisan Mersing berusia sekitar Karbon-Perm. Pemetaan geologi yang terperinci telah dilakukan di kawasan ini menggunakan kaedah grid bagi menghasilkan peta litologi dan struktur. Struktur geologi yang dijumpai di kawasan ini ialah lipatan, sesar, kekar, telerang dan ira. Terdapat empat arah lipatan di kawasan ini. Sesar mendatar kanan (dekstral) dan kiri (sinistral) banyak dicerap. Sesar mendatar kiri di kawasan ini wujud dalam dua arah, iaitu timur-tenggara (TTG) dan tenggara (TG) manakala sesar mendatar kanan berarah hampir utara-selatan (U-S) hingga timurlaut (TL). Empat set kekar ditemui di kawasan ini. Telerang pula mempunyai lima arah utama iaitu U222°T, U316°T, U(54-60)°T, U(84-90)°T dan U114°T. Di kawasan ini terdapat dua jenis ira iaitu ira sabak dan ira retakan. Secara keseluruhannya, kawasan ini ditafsirkan telah mengalami empat fasa canggaan. Canggaan yang pertama (D1) dihasilkan oleh mampatan berarah timur-timurlaut, membentuk lipatan ketat yang mempunyai paksi menunjam ke utara-baratlaut (selatan-tenggara). Canggaan kedua (D2) pula dengan mampatan berarah timur-barat menerbitkan struktur lipatan yang terlipat semula dengan paksi menunjam ke utara. Selain itu, canggaan ini juga membentuk sesar mendatar konjugat kanan dan kiri masing-masing berjurus U55°T dan U112°T berserta telerang. Canggaan ketiga (D3) dengan mampatan berarah timur-tenggara, membentuk lipatan terbuka dengan paksinya menunjam ke arah utara-timurlaut (selatan–baratdaya), sesar mendatar kiri berarah U140°T dan telerang. Canggaan keempat (D4) pula dengan mampatan berarah utara-timurlaut menerbitkan lipatan terbuka yang paksinya menunjam hampir timur (barat), sesar mendatar kanan berarah hampir utara-selatan berserta telerang.

 

Abstract: The study area is situated along the western part of Teluk Bangka, Mersing where the rocks are exposed on the coast. The lithology observed here consists of the Permo-Carboniferous metaquartzite, phyllite and interbedded metaquartzite and phyllite, known as Mersing Bed. A detailed geological mapping has been done in this area using a grid method to produce a lithologic and structural map. Geological structures found are folds, faults, joints, veins and cleavages. There are four trends of folds in this area. Both right lateral (dextral) and left lateral (sinistral) faults are numerous. The left lateral faults are striking east-southeast (ESE) and southeast (SE), while right lateral faults aligning in almost north-south (N-S) to northeast (NE) directions. There are four sets of joints and five sets of veins were formed. The veins align in N222°E, N316°E, N(54-60)°E, N(84-90)°E and N114°E. There are experienced two types of cleavages, i.e. slaty and fracture cleavages. It is interpreted that this area had suffered four phases of deformation. The first deformation (D1) was related to the compression from east-northeast, forming tight folds with the axis plunging towards north-northwest (south-southeast). The second deformation (D2) resulted from east-west compression producing refolded folds plunging north. This deformation was also responsible for the formation of the conjugate right and left lateral slip faults striking N55°E and N112°E respectively. The third deformation (D3) related to the east-southeast compression, forming open folds plunging north-northeast (south-southwest), left lateral fault striking N140°E and veins. The fourth deformation (D4) with compression from north-northeast was responsible in the formation of almost east-west plunging open folds, north-south striking right lateral faults.