Ryan Dwi Wahyu Ardi
Geological Engineering Study Program, Faculty Of Earth Sciences And Technology, Institut Teknologi Bandung

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Multi-method Approach in Fulfilling Clean Water Resources for Inhabitants in A Rural Area: Preliminary Results Aditya Pratama; Abdullah Husna; Ryan Dwi Wahyu Ardi; Yogi Adi Prasetya
JURNAL PERTAMBANGAN DAN LINGKUNGAN Vol 2, No 2 (2021): Desember 2021
Publisher : Universitas Muhammadiyah Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31764/jpl.v2i2.6148

Abstract

Clean water scarcity is among the crucial issues for inhabitants at Cikakaban Village, Tasikmalaya City. The complexity of the geological and hydrogeological conditions around Cikakaban Village makes groundwater exploration quite difficult. Regionally, Cikakaban Village has low aquifer productivity and is located at the contact of two formations which are passed by a fault. Therefore, a multi-method approach should be used in water sources exploration to obtain comprehensive results. In this paper, we presented the preliminary results which consist of the detailed geological and hydrogeological conditions of Cikakaban Village and its surroundings based on direct field observations. These observations aim to know the lithology that composes the research area and its characteristics, the potential of aquifers and water resources around the research area, as well as an overview of the distribution of groundwater depth and its flow direction. Geological survey includes observation of outcrops, both lithological description and geological structure evidence. Meanwhile, hydrogeological survey includes observation wells (location plotting, measuring ground water level elevation and depth, and checking water quality), as well as observation of the other potential water resources around Cikakaban Village. It can be inferred that rocks underlying the study area have fine grain sizes, dominated by claystone and tuff. However, the presence of geological structure causes these rocks to potentially become productive aquifers. Other potential water sources around the research area are springs and intermittent rivers.
MIDDLE MIOCENE BIOSTRATIGRAPHY AND PALEO-OCEANOGRAPHY OF SUPIORI ISLAND, PAPUA BASED ON CALCAREOUS NANNOFOSIL ASSEMBLAGES Ryan Dwi Wahyu Ardi; Nadila Novandaru; Istiana Istiana; Alviyanda Alviyanda; Rubiyanto Kapid; G.M. Lucky Junursyah; Rahmat Y Saragih
Bulletin of Geology Vol 3 No 3 (2019): Bulletin of Geology
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.2019.3.3.4

Abstract

Calcareous nannofossil assemblages have been analysed from three stratigraphic sections on Supiori Island to determine biozonation and paleo-oceanographic condition. Based on Neogene Calcareous Nannofossils Zonation (Martini, 1971), section BK 78 (Wainukendi Formation) classified into three zones, which coeval to NN7–NN9 and or younger (Middle Miocene). Section BK 95 (Napisendi Formation) categorised into five zones, which equivalent to NN5–NN9 (Middle Miocene), and section BK 98 (Wafordori Formation) is considered to be equivalent to NN7 (Middle Miocene). Those results indicate a correlatable interval (NN7) and an interfinger contact between Wainukendi, Wafordori, and Napisendi Formations. Paleo-oceanographic parameters namely thermocline/nutricline depth and paleosalinity were analysed in this research. Thermocline/nutricline depth analysis from Discoaster abundance and mean coccolith size of Reticulofenestra and Coccolithus indicate sea surface condition changes from oligotrophic (NN5–NN7) to eutrophic (early NN8) and then again into oligotrophic (from late NN8 to NN9). Paleosalinity analysis based on abundance comparison between Sphenolithus neoabies, Helicosphaera carteri, and Calcidiscus leptoporus denotes paleosalinity shift from normal saline (NN7) to hyposaline condition (NN8 – NN9). Those paleo-oceanographic parameters changes most likely related to the closing of Indonesian Seaway due to regional uplift, which triggered the formation of proto West Pacific Warm Pool (WPWP), Equatorial Under Current (EUC), and eventually a La Nina-like condition on late Middle Miocene (NN8–NN9).
BIOSTRATIGRAFI DAN PALEOEKOLOGI WILAYAH LEPAS PANTAI BARAT DAYA SUMBA SEJAK PLEISTOSEN AKHIR BERDASARKAN KUMPULAN FORAMINIFERA PLANKTONIK Ardi, Ryan Dwi Wahyu; Maryunani, Khoiril Anwar; Yulianto, Eko; Putra, Purna Sulastya; Nugroho, Septriono Hari
Bulletin of Geology Vol 3 No 2 (2019): Bulletin of Geology
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.2019.3.2.3

Abstract

Foraminifera are microfaunas/microfossils that frequently applied in geology especially for biostratigraphy and paleoecological analysis. This research aim to create biozonation and paleoecological analysis in the region off the southwest coast of Sumba based on planktonic foraminiferal assemblages. This region heavily affected by northwest monsoon – southeast monsoon shift and located next to one of the ITF’s outflow paths (Ombai Strait – Savu Sea) which eventually form its ecological condition. A 235 cm long deep sea sediment core coded ST08 will be used as research material. Foraminifera specimens were determined quantitatively by observing approximately 300 specimens for each split. Each taxon determined from that part then calculated for each individu that was found while different taxa determined from other splits are considered to be one. Biozonation was determined based on either Blow biozonation or Bolli and Saunders biozonation. One zone was obtained based on Blow biozonation which is N23 zone, equal to Pleistocene – Holocene. Two zones were determined based on Bolli and Saunders biozonation which are Globigerinella calida – Clavarotella bermudezi zone (below 147 cm depth), equal to Late Pleistocene and Globorotalia fimbriata zone (0 – 147 cm depth), equal to Holocene. Paleocological analysis focused on the thermocline depth parameter inferred from the relative abundance of thermocline dweller taxa that consist of Neogloboquadrina dutertrei, Puleniatina obliqueloculata, and Globorotalia menardii. Themocline dweller abundance were relatively higher during Pleistocene (49,76 – 75,66%, average 60,01%), indicating shallower thermocline (eutropic condition) while during Holocene its abundance relatively lower (33,90 – 57, 17%, average 45,77%), which indicated thermocline deepening (more oligotropic condition). Those conditions were related to the southeast monsoon domination during Pleistocene (stronger ITF) before its weakening on Holocene which induced northwest monsoon strengthening (weaker ITF).
Mikrofasies Batugamping Formasi Sentolo, Daerah Karangsari, Kulon Progo, Daerah Istimewa Yogyakarta Nurhidayah, Efrilia Mahdilah; Akmaluddin, Akmaluddin; Ardi, Ryan Dwi Wahyu; Maulida, Nisa' Khofiyan; Sholichah, Wahyunia Mar'atus
Jurnal Geosains dan Teknologi Vol 8, No 1 (2025)
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jgt.8.1.2025.49-59

Abstract

Penelitian mikrofasies batugamping Formasi Sentolo dilakukan di daerah Karangsari, Kulon Progo, Yogyakarta. Formasi Sentolo terdiri dari batugamping dan perselingan napal-batugamping. Penelitian ini bertujuan untuk mengetahui variasi mikrofasies dan lingkungan pengendapanpada batugamping di Formasi Sentolo menggunakan analisis petrografi. Analisis dilakukan terhadap sepuluh sampel batugamping menggunakan metode petrografi untuk menginterpretasikan tipe mikrofasies dan lingkungan pengendapan, dengan delapan sampel di antaranya juga dianalisis foraminifera bentik besar untuk menentukan umur relatif. Karakteristik yang paling menonjol pada hasil analisis komposisi batuan adalah melimpahnya fragmen fosil foraminifera bentik besar dan alga. Analisis foraminifera bentik besar pada lokasi penelitian menunjukan umur Miosen (Te5–Tf), berdasarkan kehadiran asosiasi spesies Operculinoides panamensis, Amphistegina bowdenensis, Amphistegina lessonii, Operculina sp., dan Elphidium sp. Dua mikrofasies utama berhasil diidentifikasi, yaitu fasies foraminiferal wackestone yang mewakili lingkungan laut dalam toe-of-slope (FZ3), dan fasies amphistegina grainstone/ packstone yang mencerminkan lingkungan open marine (FZ7) pada bagian backreef. Perubahan lingkungan pengendapan dari laut dalam menuju laut dangkal mengindikasikan adanya pengaruh fluktuasi muka air laut serta kontrol morfologi sisa gunungapi purba terhadap sistem pengendapan karbonat di Pegunungan Kulon Progo.
LAST GLACIAL MAXIMUM – HOLOCENE RAINFALL SHIFTS IN THE WESTERN SAVU STRAIT BASED ON GEOCHEMICAL PROXIES Ardi, Ryan Dwi Wahyu; Aswan, Aswan; Maryunani, Khoiril Anwar; Yulianto, Eko; Putra, Purna Sulastya; Nugroho, Septriono Hari; Nurhidayah, Efrilia Mahdilah
JGE (Jurnal Geofisika Eksplorasi) Vol. 11 No. 2 (2025)
Publisher : Engineering Faculty Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jge.v11i2.493

Abstract

The Indo-Pacific Warm Pool significantly influences global atmospheric circulation, with tropical rainfall patterns highly sensitive to glacial–interglacial climate changes. During the Last Glacial Maximum (LGM), approximately 26,500 years before present, lower insolation, expanded ice sheets, and reduced sea levels weakened the Australian–Indonesian Monsoon (AIM) due to a southward shift of the Intertropical Convergence Zone (ITCZ). In contrast, the Holocene period experienced intensified monsoon systems and increased precipitation. However, high-resolution hydroclimate reconstructions from the western Savu Strait remain scarce. This study reconstructs rainfall variability from the LGM to the Holocene using geochemical proxies from sediment core ST10 (at 1 cm interval), located in the western Savu Strait. Three elemental ratios (Ti/Ca, K/Ca, and Rb/Sr) from X-ray fluorescence (XRF) core scanning were used to indicate terrigenous input, chemical weathering, and fluvial discharge. The age model was established using radiocarbon dating and stable isotope alignment with the Greenland ice core δ¹⁸O record. Log-transformed elemental ratios reveal four intervals of increased rainfall: the LGM, Heinrich Event 1 (HE1), Younger Dryas to Early Holocene, and the Late Holocene. These periods are characterized by elevated Ti/Ca, K/Ca, and Rb/Sr values, suggesting enhanced monsoonal rainfall and continental runoff. Conversely, lower proxy values during the Early Deglaciation, Bølling–Allerød, and Mid-Holocene indicate drier climatic conditions. These patterns align with regional proxy records from southwest Sumba and the Timor Sea, confirming the reliability of elemental ratios in reconstructing past hydroclimate variability. This study provides the first continuous record of rainfall shifts in the western Savu Strait from the LGM to Holocene and contributes to understanding long-term monsoon dynamics in southeastern Indonesia, highlighting the complex response of tropical hydroclimate to global climate forcing.