Kemala Wijayanti, Kemala
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Karakteristik Jasper Merah di Pulau Jawa Bagian Selatan Berdasarkan Analisis SEM dan XRF Wijayanti, Kemala; Rosana, Mega Fatimah; Yuningsih, Euis Tintin; Sulistyawan, Raden Isnu Hajar
Jurnal Geologi dan Sumberdaya Mineral Vol 18, No 1 (2017): Jurnal Geologi dan Sumberdaya Mineral
Publisher : Pusat Survei Geologi

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (320.014 KB)

Abstract

Jasper is one type of microcrystalline silica which include to gemstone variety. Indonesia has a high potential of jasper because its variety and a huge number of jasper that widely spread in Indonesia. There are 3 (three) types of jaspers that usually found in Indonesia, red jasper, yellow jasper, and green jasper. Among three of them, red jasper is much more abundant especially in Southern Java.Therefore, this research was held to observe the differences of red jasper's characteristic in three places in Java, i.e., Bungbulang – Garut, Samigaluh – Yogyakarta, and Donorojo – Pacitan areas. To attain the purpose of this research, SEM analysis is used to compare their textures and XRF for the chemical compositions.The research concludes that the red jaspers from those three places have the same texture, the granulated texture which derived from quartz texture. The grain size seems to increased from west to east. From the chemical composition it can be seen that the red color of jasper is strongly affected by Fe, Cr, and V. The Ti elements of red jasper also increased from west to east because there is a high Ti content in Pacitan's red jasper and perhaps by the combination of those elements resulting the purple color in red jasper.Keywords - red jasper, gemstone, composition, element, Southern Java
Geophysical Approach And Geochemistry Correlated To Discover Underground Water Flow Indicator To Mud Volcano In Quarter Volcanic System Ridwan, Pandji; Fachrudin, Kurnia Arfiansyah; Ramadian, Aldrin; Wijayanti, Kemala
Journal of Geological Sciences and Applied Geology Vol 4, No 3 (2021): Journal of Geological Science and Applied Geology
Publisher : Faculty of Geological Engineering, Universitas Padjadjaran

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24198/gsag.v4i3.32220

Abstract

No less than 108 million meter3 of hot mud has been spread out from the earth since the burst first occurred in Porong, Sidoarjo at May 29th, 2006 until this day. This mud has covered the area for more than 717.027 ha with inundation that reaches many meters deep. If a close attention is being paid, 70% contain of the mud is water. Because of that, water volumes which have been produced is no less than 75 million m3.  Therefore, information of subsurface geological data of the region around the burst site is needed to find out where the source of water came from. This study is meant to get a subsurface image of Porong so that a subsurface water channel that supplies water to the centre of mud burst can be found. Geophysical data, which is in the form of gravity method, Audio Magnetotelluric (AMT), and Magnetotelluric are correlated with geochemical study of elements of the mud. Pb, Zn, Mn, Ag, Cd, Sb, Au, Se, and Hg elements which the hot mud have is  indication of hydrothermal influence at 100°C that come from the quarter volcanic system around the mud source such as Pananggungan Mountain and Arjuna Mountain.  Not only that, result of measurement, gravity interpretation in form of Bouger anomaly, AMT, and MT data show three lineament structures in NE – SW direction in Porong, Sidoarjo. One of them extends from Watukosek Village in Pananggungan Mountain to the mud lake of Sidoarjo. This lineament is interpreted as a fault zone with 0.2 – 0.7 km deep in Watukosek Village and even gets deeper in the mud lake area (1.5 – 3 km deep). The Fault is a permeable zone which acts as the subsurface water channel. This channel is interpreted as the way of water flow, so the mud burst still continuous until this day. 
Karakteristik Hidrogeokimia dan Isotop Air Tanah di Pesisir Kota Balikpapan, Kalimantan Timur Irsyadulhaq, Irsyadulhaq; Arifin, Arifin; Ramdhan, Agus Muhammad; Rachmayani, Rima; Iskandar, Irwan; Wijayanti, Kemala
Bulletin of Geology Vol 8 No 1 (2024): Bulletin of Geology Vol. 8 no. 1
Publisher : Fakultas Ilmu dan Teknologi Kebumian (FITB), Institut Teknologi Bandung (ITB)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/bull.geol.2024.8.1.3

Abstract

Daerah studi meliputi wilayah pesisir Kota Balikpapan yang memiliki jumlah penduduk sekitar 733 ribu, dengan persentase pemanfaatan air tanah untuk keperluan domestik diperkirakan sebesar 70%. Sebagai kota penyangga bagi Ibu Kota Nusantara (IKN), diperkirakan akan terjadi peningkatan jumlah penduduk di Balikpapan pada masa yang akan datang yang dapat berdampak terhadap meningkatnya jumlah pemanfaatan air tanah dan perubahan kualitas air tanah. Studiini mengkaji karakteristik hidrogeokimia dan isotop air tanah, mengidentifikasi keberadaan dan penyebab fenomena intrusi air laut, serta merekonstruksi model konseptual hidrogeologi menggunakan data sampel air tanah, litologi, seismik, muka air tanah, dan pasangsurut air laut. Hasil studi ini menunjukkan nilai Total Dissolved Solids (TDS) air tanah berkisar antara 141 –11.023 mg/ldan pH sampel air tanah berkisar antara 4,49 hingga 9,29. Fasies air tanah terdiri dari mixed cation/HCO3-, Na+/Cl-, Na+/HCO3-,Ca2+/HCO3-,dan Na+/mixed anion. Komposisi isotop 18O dan 2H mengindikasikan evolusi kimia air tanah melalui proses evaporasi dan interaksi air tanah dengan batuan. Indikasi intrusi air laut ditemukan pada satu sampel air tanah (titik M-2.1) pada akuifer di kedalaman 30 –33 m. Intrusi air laut tersebut diperkirakan terjadi secaraalamiah. Perhitungan rasio pencampuran menunjukkan komposisi air tanah tawar sekitar 60% dan air laut sebesar 40%. Adapun model konseptual hidrogeologi di daerah studimenunjukkan perselingan batupasir dan batulempung atau perselingan akuifer dengan akuitar, dimana akuifer pada kedalaman 30 hingga 33 m di titik M-2.1 diinterpretasi terhubung dengan laut. Kata kunci: air tanah, Balikpapan, hidrogeokimia, isotop, intrusi air laut