Email this article 
Hide
Show all
Komparasi Geokimia Batuan Gunung Api Kuarter dan Tersier di Tepian Selatan Lampung
DOI: http://dx.doi.org/10.55981/eksplorium.2020.6053
Abstract
ABSTRAK Keterdapatan batuan gunung api di Sumatra diakibatkan oleh penunjaman Lempeng Samudra India-Australia ke bawah Lempeng West Sumatra sejak Eosen. Tanggamus adalah kabupaten di ujung selatan Lampung dengan keterdapatan beberapa unit batuan gunung api berumur Tersier maupun Kuarter. Studi ini bertujuan untuk membandingkan komposisi geokimia batuan gunung api Tersier Formasi Hulusimpang dengan batuan gunung api Kuarter Gunung Tanggamus. Perangkat XRF dan ICP-MS dimanfaatkan untuk mengetahui kadar oksida utama, unsur jejak, dan unsur tanah jarang pada penelitian ini. Berdasarkan karakter geokimia, sampel dari Formasi Hulusimpang adalah batuan gunung api kalk-alkali, metalumina hingga peralumina, dan dalam rentang trakiandesit basaltik hingga riolit. Sampel batuan gunung api berumur Kuarter berada pada rentang kadar silika yang lebih sempit dan cenderung metalumina. Studi ini membuktikan bahwa kedua kelompok batuan berasal dari magma yang sama, tetapi dengan kontaminasi kerak selama diferensiasi. Proses pembentukan yang berbeda pada kedua kelompok batuan diperjelas oleh derajat kemiringan kurva diagram laba-laba UTJ dan jenis anomali Eu.
ABSTRACT The presence of volcanic rocks in Sumatra is due to the subduction of the Indian-Australian Ocean Plate under the West Sumatra Plate since the Eocene. Tanggamus Regency situated at the southern edge of Lampung with the occurrence of several Tertiary and Quaternary volcanic rock units. The aim of this study is to compare the geochemical composition of Tertiary volcanic rocks from the Hulusimpang Formation and Quaternary volcanic rocks from Mount Tanggamus in the Tanggamus Regency. XRF and ICP-MS devices were used to determine the compositions of major oxides, trace elements, and rare earth elements in this study. Based on geochemical characters, samples from the Hulusimpang Formation are calc-alkaline volcanic rocks, metaluminous to peraluminous, and in the basaltic trachyandesite to rhyolite ranges. Quaternary samples are in a narrower range of silica content and tend to be metaluminous. This study proves that the two rock groups originate from the same magma but with crustal contamination during differentiation. The two volcanic should experience through different formation processes based on the slope of the heavy-REE and the type of Eu anomaly.
Keywords
Full Text:
PDF (Bahasa Indonesia)References
[1] Y. Eyuboglu, M. Santosh, dan S.L. Chung, “Crystal Fractionation of Adakitic Magmas in the Crust–Mantle Transition Zone: Petrology, Geochemistry and U–Pb Zircon Chronology of the Seme Adakites, Eastern Pontides, NE Turkey,” Lithos, 121(1–4), 151–166, 2011, doi: 10.1016/j.lithos.2010.10.012.
[2] R.R. Almeev, J.I. Kimura, A.A. Ariskin, dan A.Y. Ozerov, “Decoding Crystal Fractionation in Calc-Alkaline Magmas from the Bezymianny Volcano (Kamchatka, Russia) using Mineral and Bulk Rock Compositions”, Journal of Volcanology and Geothermal Research, 263, 141–171, 2013, doi: 10.1016/j.jvolgeores.2013.01.003.
[3] R. Irzon, “Comagmatic Andesite and Dacite in Mount Ijo, Kulonprogo: A Geochemistry Perspective,” Jurnal Geologi dan Sumberdaya Mineral, 19(4), 221–231, 2018, doi: 10.33332/jgsm.geologi.v19i4.185.
[4] B. Tuller-Ross, P. S. Savage, H. Chen, dan K Wang, "Potassium Isotope Fractionation during Magmatic Differentiation of Basalt to Rhyolite,” Chemical Geology, 525, 37–45, 2019, doi: 10.1016/j.chemgeo.2019.07.017.
[5] K. S. Widana, dan B. Priadi, “Karakteristik Unsur Jejak Dalam Diskriminasi Magmatisme Granitoid Pulau Bangka,” Eksplorium, 36(1), 1–16, 2015, doi: 10.17146/eksplorium.2015.36.1. 2766.
[6] I. Zulkarnain, “Sumatra is not a Homogenous Segment of Gondwana Derived Continental Blocks: A New Sight based on Geochemical Signatures of Pasaman Volcanic in West Sumatera,” RISET Geologi dan Pertambangan, 26(1), 1–13, 2016, doi: 10.14203/risetgeotam2016.v26.271.
[7] R. Irzon, I. Syafri, A. A. Ghani, A. Prabowo, J. Hutabarat, dan P. Sendjaja, ”Petrography and Geochemistry of the Pinkish Lagoi Granite, Bintan Island: Implication to Magmatic Differentiation, Classification, and Tectonic History,” Bulletin of the Geological Society of Malaysia, 69, 27–37, 2020, doi: 10.7186/bgsm69202003.
[8] A. Bani, G. Echevarria, E. Montargès-Pelletier, F. Gjoka, S. Sulejman, dan J. L. Morel, “Pedogenesis and Nickel Biogeochemistry in a Typical Albanian Ultramafic Toposequence,” Environmental Monitoring and Assessment, 187(7), 4431–4442, 2014, doi: 10.1007/s10661-014-3709-6.
[9] R. Irzon dan B. Abdullah, ”Element Mobilization During Weathering Process of Ultramafic Complex in North Konawe Regency, Southeast Sulawesi Based on A Profile from Asera,” Indonesian Journal on Geoscience, 5(3), 277–90, 2018, doi: 10.17014/ijog.5.3.277-290.
[10] E. H. Suryawan, A. Hilyah, M. H. M. Fajar, dan A. Pajrin, “Identifikasi dan Penentuan Volume Endapan Nikel Laterit Berdasarkan Data Geolistrik Metode Sounding Studi Kasus Blok Selatan Daerah Pomalaa, Sulawesi Tenggara,” Jurnal Geosaintek, 5(2), 53–60, 2019, doi: 10.12962/j25023659.v5i2.5393.
[11] Z. Azadbakht, D. R. Lentz, C. R. M. McFarlane, dan J. B. Whalen, “Using Magmatic Biotite Chemistry to Differentiate Barren and Mineralized Silurian–Devonian Granitoids of New Brunswick, Canada,” Contributions to Mineralogy and Petrology, 175(7), 1–24, 2020, doi: 10.1007/s00410-020-01703-2.
[12] H. Yilmaz, F. N. Sonmez, dan E. J. M. Carranza, “Discovery of Au–Ag Mineralization by Stream Sediment and Soil Geochemical Exploration in Metamorphic Terrain in Western Turkey,” Journal of Geochemical Exploration, 158, 55–73, 2015, doi: 10.1016/ j.gexplo.2015.07.003.
[13] R. Irzon, “Thorium and Total REE Correlation in Stream Sediment Samples from Lingga Regency,” Eksplorium, 39(1), 1–16, 2018, doi: 10.17146/eksplorium.2018.39.1.3558.
[14] M. L. Benhaddya dan M. Hadjel, “Spatial Distribution and Contamination Assessment of Heavy Metals in Surface Soils of Hassi Messaoud, Algeria,” Environmental Earth Sciences, 71(3), 1473–1486, 2014, doi: 10.1007/s12665-013-2552-3.
[15] R. Irzon, I. Syafri, J. Hutabarat, P. Sendjaja, dan S. Permanadewi, “Heavy Metals Content and Pollution in Tin Tailings from Singkep Island, Riau, Indonesia,” Sains Malaysiana, 47(11), 2609–2616, 2018, doi: 10.17576/jsm-2018-4711-03.
[16] A. J. Barber dan M. J. Crow, “Structure of Sumatra and its Implications for the Tectonic Assembly of Southeast Asia and the Destruction of Paleotethys,” Island Arc, 18(1), 3–20, 2009, doi: 10.1111/j.1440-1738.2008.00631.x.
[17] I. Metcalfe, “Tectonic Evolution of Sundaland,” Bulletin of the Geological Society of Malaysia, 63, 27–60, 2017, doi: 10.7186/bgsm63201702.
[18] M. J. Salisbury, J. R. Patton, A. J. R Kent, C. Goldfinger, Y. Djadjadihardja, dan U. Hanifa, “Deep-Sea Ash Layers Reveal Evidence for Large, Late Pleistocene and Holocene Explosive Activity from Sumatra, Indonesia,” Journal of Volcanology and Geothermal Research, 231–232, 61–71, 2012, doi: 10.1016/j.jvolgeores. 2012.03.007.
[19] J. Stimac, A. M. Sihotang, W. Mussofan, M. Baroek, C. Jones, J. N. Moore, dan A. K. Schmitt, “Geologic Controls on the Muara Laboh Geothermal System, Sumatra, Indonesia,” Geothermics, 82, 97–120, 2019, doi: 10.1016/j.geothermics.2019.06.002.
[20] S. Liu, I. Suardi, M. Zheng, D. Yang, X. Huang, dan P. Tong, “Slab Morphology Beneath Northern Sumatra Revealed by Regional and Teleseismic Traveltime Tomography,” Journal of Geophysical Research: Solid Earth, 124(10), 10544–10564, 2019, doi: 10.1029/ 2019JB017625.
[21] A. J. Barber, “The origin of the Woyla Terranes in Sumatra and the Late Mesozoic Evolution of the Sundaland Margin,” Journal of Asian Earth Sciences, 18(6), 713–738, 2000, doi: 10.1016/S1367-9120(00)00024-9.
[22] V. Acocella, O. Bellier, L. Sandri, M. Sébrier, dan S. Pramumijoyo, “Weak Tectono-Magmatic Relationships along an Obliquely Convergent Plate Boundary: Sumatra, Indonesia,” Frontiers in Earth Science, 6, 3, 2018, doi: 10.3389/feart.2018.00003.
[23] I. Zulkarnain, “Petrogenesis Batuan Vulkanik Daerah Tambang Emas Lebong Tandai, Provinsi Bengkulu, Berdasarkan Karakter Geokimianya,” Jurnal Geologi Indonesia, 3(2), 57–73, 2008, doi: 10.17014/ijog.vol3no2.20081.
[24] T. C. Amin, Sidarto, S. Santosa, dan W. Gunawan, “Peta Geologi Lembar Kotaagung, Sumatra,” Bandung: Pusat Penelitian dan Pengembangan Geologi, 1993.
[25] A. J. Barber, M. J. Crow, dan J. Milsom (Eds.), Sumatra: Geology, Resources and Tectonic Evolution, London: Geological Society , 2005.
[26] E. A. K. Middlemost, “Naming Materials in the Magma/Igneous Rock System,” Earth-Science Reviews, 37(3-4), 215–224, 1994, doi: 10.1016/0012-8252(94)90029-9.
[27] M. H. Roselee, A. A. Ghani, dan M. R. Umor, “Petrology and Geochemistry of Igneous Rocks from Southern Tioman Island, Pahang, Peninsular Malaysia,” Bulletin of the Geological Society of Malaysia, 62, 79–89, 2016, doi: 10.7186/bgsm62201611.
[28] K. S. Widana, “Petrografi dan Geokimia Unsur Utama Granitoid Pulau Bangka: Kajian Awal Tektonomagmatisme,” Eksplorium, 34(2), 75–88, 2013, doi: 10.17146/eksplorium.2013.34.2.708.
[29] G. Abdul-Jabbar, H. Rachmat, dan M. Nakagawa, “Temporal Change of Barujari Volcano Magmatic Process: Inferred from Petrological Study of Erupted Products Since AD 1944,” Journal of Physics: Conference Series, 1363(1), 012030, 2019, doi: 10.1088/1742-6596/1363/1/012030.
[30] A. K. El-Shazly, D. D. Sanderson, dan J. Napier, “Petrogenesis of I-type Granitoids from the Melrose Stock, East-Central Nevada,” International Geology Review, 53(13), 1522–1558, 2011, doi: 10.1080/ 00206811003755396.
[31] R. Irzon, “Contrasting Two Facies of Muncung Granite in Lingga Regency Using Major, Trace, and Rare Earth Element Geochemistry,” Indonesian Journal on Geoscience, 2(1), 23–33, 2015, doi: 10.17014/ijog.2.1.23-33.
[32] W. V. Boynton, “Cosmochemistry of the Rare Earth Elements: Meteorite Studies,” Developments in Geochemistry, 2, 63–114, 1984, doi: 10.1016/B978-0-444-42148-7.50008-3.
Refbacks
- There are currently no refbacks.
Copyright EKSPLORIUM: Buletin Pusat Pengembangan Bahan Galian Nuklir (e-ISSN 2503-426x p-ISSN 0854-1418)
National Research and Innovation Agency (BRIN), KA. B.J. Habibie, Jl. M.H. Thamrin No.8, Jakarta, 10340, Indonesia.
