CLASSIFICATION OF CRYSTAL SIZE DISTRIBUTION FOR LAVA AND INTRUSION IN SOME VOLCANOES AND INTRUSION IN THE SUNDA ARC
The subduction tectonic process that occurs in the Sunda Arc causes volcanism continue to develop and making the Sunda Arc have a composition of igneous rocks, both volcanic and plutonic. One of the differences between the two types of igneous rock is the texture of the crystall size, which shows th...
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| Format: | Theses |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/82963 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | The subduction tectonic process that occurs in the Sunda Arc causes volcanism continue to develop and making the Sunda Arc have a composition of igneous rocks, both volcanic and plutonic. One of the differences between the two types of igneous rock is the texture of the crystall size, which shows that plutonic igneous rock has a relatively larger crystall size compared to volcanic rock as a function of cooling rate time. The total samples used in this research were 12 samples from lava and intrusion. They taken from various locations in the Sunda Arc which were taken either directly or through literature studies. The samples used came from Baloy, Central Kalimantan, Raung Volcano, Kelud Volcano, Lasem Volcano, Karangsambung Pillow Lava, Ciremai Volcano, Mount Batu Bandung, Mount Parang Purwakarta, Mount Bongkok Purwakarta, and 3 samples from the granitoid complex in Kotabatu, Central Lampung. The method used is crystal size distribution (CSD) to determine the diversity of crystal sizes and densities. Image data, both petrographic and scanning electron microscopy backscattered electron image (SEM-BSE) were collected for crystall size analysis using Image-J software. Based on the results of CSD data analysis, in general the intrusion samples show a more dominant crystal growth pattern compared to the lava samples which show a nucleation growth pattern. In addition, the magma storage time in intrusion samples has a relatively faster time and variations that are not too far, namely 111.62, 138.35, 161.02, 135.4, 82.6, and 185 years, compared to variations in time Magma storage in lava samples is 312.31, 225.09, 171.43, 204.08, 670.42, and 136.17 years. In general, the cooling rate of intrusions is higher than that of lava samples, the highest cooling rates in intrusive samples are in granite complex samples with cooling rates of 8.47.10-5, 8.16.10-5, and 8.89.10-5 K/s, while For the lava sample, the highest cooling rate was the Mount Kelud sample with 3.47.10-5 K/s. Based on the data from the analysis, the cooling value limit between lava and intrusion can be drawn, namely 1.22.10-7, and the average limit for the crystal size of lava and intrusion is 0.54 mm.
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