SUTANTO, sutanto (2003) GEOLOGI DAN UMUR BATUAN VOLKANIK DAERAH BERASTAGI DAN SEKITARNYA. WAHANA TEKNIK, 5 (3). pp. 160-169. ISSN lssN 1411-044X
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Abstract
Area of Berastagi laid in nofth part of Sumatra about 25 km norlh side of Toba Lake,
tectonically, represents the paft of bow of Sunda Mountain. Movement of lndies plate against
Sumatra shaping an angle about 45" causes fault of dextral Semangko and /ess active
volcanoes in Sumatra compared to Java. Volcanoes in Sumatra have composition of andesitik,
dasityc, and riolytic with affinity of kalk-alkali and kalk-alkali potasik. Tapanuli group which
consisf of Bohorok formation, Kuet formation, and Pallet formation, and also Kuala formation
and Batumilmilformation from the group of Peusangan represent pre-teftiary bedrock underlying
directly volcanic rock of Sinabun-Sikayak area. Beside, terliary rock formation is not located in
this area- The age of radiometric of volcanic rock around the Toba Lake ranges from 5,6 x 0,14
and 0,38 ! 0,11 Ma. The oldest rock is microdiorit (in Parapat), and the youngest is Toba riolitic
Tufa. Mount of Sibayak, Mount of Pintal, and Mount of Pratektekan represent center of quarTer
volcano activities located within Singkut Calderas.
| Item Type: | Article |
|---|---|
| Subjek: | Q Science > QE Geology |
| Depositing User: | sutanto sutanto - |
| Date Deposited: | 08 Nov 2017 08:14 |
| Last Modified: | 08 Nov 2017 08:14 |
| URI: | http://eprints.upnyk.ac.id/id/eprint/12373 |
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