Article Per Year (5 Year)
p-Index From 2020 - 2025
0.23
P-Index
This Author published in this journals
All Journal Jurnal Geologi dan Sumberdaya Mineral (Journal of Geology and Mineral Resources)
Joko Subandrio
Pusat Survei Geologi
Chemistry Earth & Planetary Sciences Energy

Published : 2 Documents Claim Missing Document
Claim Missing Document
Check
Articles

Found 2 Documents
Search

 1 
Mineralogi dan Geokimia Tuf Berumur Tersier dan Kuarter di Daerah Cibadak, Sukabumi, Jawa Barat Sam Permanadewi; Sigit Maryanto; Joko Subandrio
Jurnal Geologi dan Sumberdaya Mineral Vol. 18 No. 4 (2017): Jurnal Geologi dan Sumberdaya Mineral
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v18i4.295

Abstract

Fine-grained pyroclastic rocks  found in the Cibadak area, Sukabumi divided into two groups, namely Tertiary tuff composing of Jampang Formation and Quarternary tuff as the result of  young volcanic eruptions. The relationship between mineralogy and geochemistry of those tuffs are discussed in this paper. Laboratory testing was conducted on fifty rock samples taken from the field. A kind of mineralogy composing the rock can be identified by the XRD (X-Ray Diffraction) mineralogy test, while the major oxide of the rock can be calculated with the XRF (X-Ray Fluorescence) geochemistry test. The XRD mineralogy test shows  two secondary mineral that becomes the differentiation between the two tuffs are zeolites and clay minerals. The zeolites present at most of the Tertiary tuffs as a result of the rock alteration which involves an increasing in formation temperature and pressure. Clay minerals are mostly present at the Quarternary tuffs as a result of rock wheathering on the surface. The zeolite and clay minerals are associated with almost all chemical oxides of the rocks. The chemical oxides including SiO2, Al2O3, Fe2O3, MgO, K2O, TiO, and MnO. The XRF rock-chemically characters show there are no differences of the chemical oxide components on both of these pyroclastic rock groups. Keywords: mineralogy, geochemistry, tuff, Tertiary, Quarternary.
Trace and Rare Earth Elements Compositional Change on Andesite Alteration in Kaligesing, Purworejo Joko Subandrio; Ronaldo Irzon
Jurnal Geologi dan Sumberdaya Mineral Vol. 21 No. 1 (2020): Jurnal Geologi dan Sumberdaya Mineral
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33332/jgsm.geologi.v21i1.452

Abstract

The change of chemical composition because of hydrothermal alteration process is related to the modification on mineralogy and elements mobility. Different alteration conditions could lead to dissimilar geochemical character. This study aims to discuss the alteration effect on trace and rare earth elements composition of an andesite outcrop with hydrothermal alteration in Kaligesing, Purworejo, Central Java Province. Microscopic analysis at Central for Geological Survey was applied to determine the modal mineral composition of the selected samples whilst trace and rare earth elements abundances was measured using Inductively Coupled Plasma – Mass Spectrometry. Plagioclase is the major phenocryst embedded in the fine-grained feldspar and glass groundmass of relatively fresh andesite. On the other hand, sericite, chlorite, epidote, and iron oxide are detected in the altered rock. The more Sr and Rb compositions on unaltered sample exhibit their common existence in plagioclase. The bigger Rb/Sr and the lower Ba/Sr ratios inward to the center of alteration might indicate the more degree of K-bearing mineral formation than Ca-rich mineral alteration. The Ba/Zr escalation and Zr/Y reduction from relatively fresh rock through to the vein of the studied samples are parallel to the previous investigation about andesite alteration. Chondrite-normalized rare-earth elements (REE) pattern of unaltered, altered, and vein samples depicts similar patterns: strong enrichment of Low REE, positive Eu anomaly, and relatively flat high REE. The decrease of Eu anomaly may reflect the reduction of plagioclase modal composition because of alteration and might indicate a reductive alteration state.Keywords: Alteration, andesite, geochemistry, trace and rare earth elements.
Co-Authors Ronaldo Irzon Sam Permanadewi Sigit Maryanto