Analisis Morfotektonik daerah Pasar Usang, Kota Padang Panjang, Sumatera Barat berdasarkan metode Geomorfologi kuantitatif

Mukhlis Maihendra Ismail, Edy Sutriyono

Abstract


Studi tentang morfotektonik telah dilakukan di daerah Pasar Usang kota Padang Panjang dengan melakukan observasi lapangan dan analisis DEMNas. Daerah penelitian terletak di cekungan depan busur (fore-arc basin), dan disusun oleh lima satuan litologi, dari tua ke muda berturut-turut Formasi Gamping (Perem), Formasi Maihan (Perem), Formasi Granitik (Miosen), Formasi Gunung Singgalang dan Tandikat (Kuarter), dan Formasi Gunung Marapi (Kuarter). Hasil analisis morfometri memperlihatkan tiga satuan bentuk lahan yaitu Perbukitan Landai Denudasional (PLD), Perbukitan Tinggi Curam Denudasional (PTCD) dan Pegunungan Curam Denudasional (PCD). Daerah studi secara umum memiliki kelerengan yang dominan curam dengan nilai kerapatan sungai (Dd) 4,34 yang menandakan tingkat sedang, nilai faktor asimetri (Af) sebesar 69,92, nilai sinusitas muka gunung (Smf) 1,23, dan nilai rata-rata perbandingan dasar dan tinggi lembah (VF) 0,23. Berdasarkan data yang dihasilkan dari analisis morfotektonik dapat disimpulkan bahwa indeks aktifitas tektonik daerah Pasar Usang berada pada tatanan tektonik aktif. 

A study on morphotectonic has been conducted in the Pasar Usang region of Padang Panjang City using field observation and DEMNas analysis. The region is situated at the fore-arc basin and constituted by five lithologic units from older to younger consecutively Gamping Formation (Perm), Maihan Formation (Perm), Granite Formation (Miocene), Mt. Singgalang Formation, and Tandikat (Quaternary), and Mt. Merapi (Quaternary). Results of morphometric analysis reveal that there are three landform units, that is low-sloping denudational hills (PDP), steeply-sloping denudational hills (PTCD), and steeply-sloping denudational mountains (PCD). The study area generally has steep slopes with the river density value (Dd) of about 4.34, implying a medium level, an asymmetric factor (af) 69.92, sinuosity value at the mountain front (Smf) 1.23, and an average of the width-height valley (VF) 0.23. On the basis of data resulting from morphotectonic analysis, it can be concluded that the Pasar Usang region is situated in an active tectonic setting.


 

Keywords


Kemiringan Lereng;Tektonik;Smf;VF;Dd;Af

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References


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DOI: https://doi.org/10.31284/j.semitan.j.2022.v1i1.4963

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