Gunawan, Rachmi Mustika Pertiwi Putri and Suhendro, Indranova (2023) Chemical and textural studies of the youngest pyroclastic deposits at Mt. Seminung (South Sumatra, Indonesia): A window for understanding the explosive behavior of a post-caldera volcano; Kemijska i teksturna istraživanja najmlađih piroklastičnih naslaga na planini Seminung (Južna Sumatra, Indonezija): okvir za razumijevanje ponašanja vulkana nakon stvaranja kaldere. Rudarsko Geolosko Naftni Zbornik, 38 (5). 61 – 77. ISSN 03534529
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The youngest tephra deposits of Seminung Volcano in South Sumatra, Indonesia, was studied by addressing the stratigraphy (field data), componentry, petrography, glass and mineral compositions, and textural analysis of vesicles to interpret the magmatic system and eruption dynamics. Based on the componentry and grain size characteristics, the section is divided into three different units: (1) massive block and ash, (2) interbedded ash and lapilli, and (3) massive lapilli. All units include grey pumice (GP), brown pumice (BP), and scoria (SC) as the main juvenile types, while porphyritic lava occurs as the non-juvenile phase (lithics). Noteworthy, minor banded pumice (BaP) can be observed in all units, and accretionary lapilli (AL) is exclusive in the interbedded ash and lapilli unit. The similarity in mineralogy and the linear correlation of all major elements of glass compositions suggest that grey and brown pumice originated from the same shallow, biotite-bearing more silicic magma (64.5-74.9 wt. ), while scoria originates from the deeper, biotite-free less silicic magma (62.1-69.2 wt. ). The fact that grey pumice shows higher silica content and pheno-bubble fraction with lower phenocryst content than brown pumice suggests the rough stratification of the more silicic magma reservoir. Furthermore, the more silicic magma was likely intruded by the deeper less silicic magma, as indicated by the bimodal distribution of anorthite (An#) in grey and brown pumices (i.e. the peak of the high anorthite content is similar to that of scoria). Thus, the accumulation of pheno-bubble and magmatic recharge were likely responsible for triggering the eruption. Finally, the fact that juvenile clasts from units 2 and 3 had the highest matrix-vesicle number density (MVND) implies that the eruption intensity reached its peak towards the final eruption stage. © 2023, Faculty of Political Sciences, University of Zagreb. All rights reserved.
Item Type: | Article |
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Additional Information: | Cited by: 2; All Open Access, Gold Open Access |
Uncontrolled Keywords: | Indonesia; South Sumatra; Feldspar; Mica; Petrography; Silica; Stratigraphy; Indonesia; Magma mingling; Magma stratification; matrix; Matrix-bubble; Overpressure; Pheno-bubble; Seminung; Silicic magmas; Sumatra; anorthite; grain size; juvenile; phenocryst; pumice; pyroclastic deposit; silica; tephra; volcanic eruption; Glass |
Subjects: | G Geography. Anthropology. Recreation > GB Physical geography |
Divisions: | Faculty of Geography > Departemen Geografi Lingkungan |
Depositing User: | Sri JUNANDI |
Date Deposited: | 05 Nov 2024 07:10 |
Last Modified: | 05 Nov 2024 07:10 |
URI: | https://ir.lib.ugm.ac.id/id/eprint/10867 |