Istiana Istiana
Jurusan Teknik Geologi UPN "Veteran" Yogyakarta

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Perubahan Iklim Pada Pliosen Akhir Berdasarkan Studi Palinologi Formasi Tapak, Daerah Bentarsari, Kabupaten Brebes, Jawa Tengah Istiana Istiana; Zulfiah Zulfiah
Jurnal Ilmiah Geologi PANGEA Vol 9, No 1sp (2022): Jurnal Ilmiah Geologi PANGEA Edisi Spesial
Publisher : PROGRAM STUDI TEKNIK GEOLOGI FAKULTAS TEKNOLOGI MINERAL UPN VETERAN YOGYAKARTA

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31315/jigp.v9i1sp.9409

Abstract

Abstrak – Analisis polen dan spora telah dilakukan pada 20 sampel yang diambil dari singkapan vertikal di permukaan pada Formasi Tapak daerah Bentarsari. Penelitian ini bertujuan untuk merekonstruksi perubahan iklim berdasarkan data palinologi yang berlangsung selama Pliosen Akhir pada Formasi Tapak saat diendapkan di Cekungan Bentarsari. Berdasarkan analisis sampel yang telah dilakukan diperoleh 30 tipe kelompok Arboreal Pollen/AP, 11 tipe kelompok Non Arboreal Pollen/NAP, 28 tipe kelompok Pteridophyta/Spora dan ditemukan 7 tipe kelompok palynomorf lainnya seperti zoomorf dan fitoplankton. Kehadiran Podocarpus imbricatus pada sampel bagian bawah dan kemunculan akhir Stenochlaenidites papuanus pada sampel bagian atas menunjukkan bahwa Formasi Tapak pada daerah penelitian berumur Pliosen Akhir. Setidaknya terdapat lima interval kejadian penting yang berhubungan dengan perubahan iklim. Dari keseluruhan interval kejadian perubahan iklim tersebut iklim pada daerah penelitian didominasi oleh iklim yang lebih hangat dan lembab. Hal tersebut didukung oleh tingginya jumlah tipe kelompok Arboreal Pollen/AP dan tipe kelompok Pteridophyta/Spora pada daerah penelitian. Kata Kunci: Palinologi, Perubahan Iklim, Cekungan Bentarsari, Palinomorf, Formasi Tapak Abstract – Abstract – Pollen and spore analysis has carried out on 20 samples taken from vertical outcrops on the surface of the Tapak Formation in the Bentarsari area. This study aims to reconstruct climate change based on palynology data during the Late Pliocene in the Tapak Formation when deposited in the Bentarsari Basin. Based on the sample analysis that has been carried out, 30 types of Arboreal Pollen/AP groups were obtained, 11 kinds of Non-Arboreal Pollen/NAP groups, 28 types of Pteridophyta/Spora groups, and found seven types of other palynomorph groups such as zoomorphs and phytoplankton. The presence of Podocarpus imbricatus in the lower part of the sample and the late appearance of Stenochlaenidites papuanus in the upper part indicate that the Tapak Formation in the study area is Late Pliocene. There are at least five crucial event intervals related to climate change. Of all the climate change event intervals, the climate in the study area is dominated by a warmer and more humid environment. This is supported by the high number of Arboreal Pollen/AP group types and Pteridophyta/Spora group types study area. Keywords: Palynology, Climate Change, Bentarsari Basin, Palinomorph, Tapak Formation
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).
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).