Woro Sri Sukapti, Woro Sri
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GEOLOGI KUARTER DATARAN PANTAI JEPARA, JAWA TENGAH Lumbanbatu, Ungkap M; Hidayat, Suyatman; Sukapti, Woro Sri; Patriani, Emma Yan
Jurnal Geologi dan Sumberdaya Mineral Vol 15, No 1 (2014): Jurnal Geologi dan Sumberdaya Mineral
Publisher : Pusat Survei Geologi

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Abstract

Untuk mengetahui dinamika Kuarter di daerah penelitian, urut-urutan lingkungan pengendapan baik secara vertikal dan mendatar perlu dilakukan. Selain itu, untuk menafsirkan proses pengisian cekungan sedimen, korelasi beberapa penampang stratigrafi sangat diperlukan. Pengumpulan data geologi bawah permukaan dilakukan dengan pemboran dangkal menggunakan bor tangan. Sejumlah 52 pemboran telah dilakukan dengan kedalaman maksimum 11,50 m dan total kedalalaman 268,61m. Berdasarkan data tersebut diketahui bahwa satuan batuan di daerah ini dapat dipisahkan Tanah penutup (S), endapan dataran banjir (FP), endapan cekungan banjir (FB), endapan alur Sungai Purba), endapan pasir dataran pantai (B), endapan pasir pematang pantai (BS), endapan rawa bakau (SW), endapan paya (LG), koral / reef (Q), endapan laut dangkal (SM), endapan volkanik / (V), endapan pre-Holosen (pHs). Secara vertikal kombinasi urut-urutan lingkungan pengendapan tersebut menghasilkan 16 tipe penampang. Hasilnya beberapa fenomena geologi dapat diamati seperti adanya perulangan lingkungan endapan rawa, satu indikasi daerah yang mengalami penurunan secara perlahan lahan. Kehadiran endapan volkanik muda berupa tuf dapat ditafsirkan sebagai hasil aktivitas Gunung api Muria paling Muda. Indikasi proses-proses progradasi atau retrogradasi garis pantai ditunjukkan oleh proporsi mangrove yang perlahan-lahan semakin berkurang sementara polen-polen grassland semakin meningkat. Dari kedalaman 150 cm, kecenderungan perubahan itu berbalik yaitu proporsi polen-polen mangrove semakin bertambah sementara polen-polen grassland semakin berkurang. Secara umum kondisi cekungan sedimen pada saat proses pengendapan adalah dalam kondisi tenang (stabil). Dengan demikian abrasi tidak berhubungan dengan kegiatan tektonika.Kata kunci : Dinamika kuarter, retrogradasi, progradasi, kondisi tenang
IDENTIFIKASI POTENSI BENCANA GEOLOGI DI DATARAN PANTAI JEPARA, JAWA TENGAH Lumbanbatu, Ungkap; Sukapti, Woro Sri; Patriani, Emma Yan
Jurnal Geologi dan Sumberdaya Mineral Vol 15, No 3 (2014): Jurnal Geologi dan Sumberdaya Mineral
Publisher : Pusat Survei Geologi

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Abstract

Identifikasi potensi bencana geologi di dataran pantai Jepara perlu dilakukan untuk mengantisipasi laju perkembangan pembangunan seiring dengan pertambahan penduduk yang sangat pesat. Oleh karena itu, perencanaan pengembangan wilayah yang baik perlu dipersiapkan. Dalam menyusun tata ruang, potensi bencana geologi dan potensi sumber daya alam harus dipertimbangkan. Metode penelitian yang digunakan adalah dengan pendekatan sedimentologi dan stratigrafi. Untuk maksud tersebut dilakukan pemboran dangkal dengan menggunakan bor tangan (hand auger). Beberapa bencana geologi dapat dikenali yaitu abrasi pantai, agradasi pantai (pendangkalan) dan kerentanan liquifaksi. Tataan geologi daerah penelitian menunjukkan bahwa, abrasi dan agradasi serta karakteristik pantai sangat boleh jadi tidak terkait dengan aktivitas tektonik.Kata kunci: bencana geologi, geologi bawah permukaan, dinamika Kuarter, Jepara
Late Holocene Pollen Record of Environmental Changes in Karimata Strait, Sunda Shelf Region Yulianto, Eko; Sukapti, Woro Sri; Dewi, Kresna Tri
Indonesian Journal on Geoscience Vol 6, No 1 (2019)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2677.631 KB) | DOI: 10.17014/ijog.6.1.41-55

Abstract

DOI: 10.17014/ijog.6.1.41-55Pollen analysis has been conducted on a 90 cm gravity core taken from the Karimata Strait to reveal pollen facies in marine sediment and Late Holocene environmental changes in the central Sunda Shelf region. The core site is at 32 m water depth and located about 170 km northwest of Bangka Island, Indonesia. Ten samples were collected at 10 cm intervals through the core. The total number of pollen grains counted in the samples varies between very low (<50 grains) to abundant (>200 grains). High frequencies (50 - 70%) of mangrove pollen are found at 90 to 40 cm indicating that pollen facies in offshore marine sediment may be comparable with those in mangrove forest floor sediment. The core site has been in a neritic environment since its early deposition ca. 1,800 yr B.P. (~150 A.D.) when mangroves vastly grew on the tidal flats of the surrounding islands and they persisted to ca. 700 yr B.P. (~1,250 A.D.). In the middle of this period, a catastrophic event speculatively due to the 535 A.D. Krakatau eruption might have responsible for the decrease of mangroves and the disappearance of benthic foraminifers. The deposition of silicious materials (tephra) due to this eruption might have provided an opportunity for benthic foraminifers to increase their population subsequently. From ca. 700 yr B.P. (~1,250 A.D.) mangroves declined, as indicated by lower frequencies of pollen grain in samples from 30 cm deep upward. It occurred simultaneously with the deposition of coarser sediment and the increase of benthic foraminifer abundance. Interplay of anthropogenic activities, strengthening ENSO cycle, and lowering erosion base level might have been responsible for these environmental changes.
Late Holocene Pollen Record of Environmental Changes in Karimata Strait, Sunda Shelf Region Yulianto, Eko; Sukapti, Woro Sri; Dewi, Kresna Tri
Indonesian Journal on Geoscience Vol 6, No 1 (2019)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2677.631 KB) | DOI: 10.17014/ijog.6.1.41-55

Abstract

DOI: 10.17014/ijog.6.1.41-55Pollen analysis has been conducted on a 90 cm gravity core taken from the Karimata Strait to reveal pollen facies in marine sediment and Late Holocene environmental changes in the central Sunda Shelf region. The core site is at 32 m water depth and located about 170 km northwest of Bangka Island, Indonesia. Ten samples were collected at 10 cm intervals through the core. The total number of pollen grains counted in the samples varies between very low (<50 grains) to abundant (>200 grains). High frequencies (50 - 70%) of mangrove pollen are found at 90 to 40 cm indicating that pollen facies in offshore marine sediment may be comparable with those in mangrove forest floor sediment. The core site has been in a neritic environment since its early deposition ca. 1,800 yr B.P. (~150 A.D.) when mangroves vastly grew on the tidal flats of the surrounding islands and they persisted to ca. 700 yr B.P. (~1,250 A.D.). In the middle of this period, a catastrophic event speculatively due to the 535 A.D. Krakatau eruption might have responsible for the decrease of mangroves and the disappearance of benthic foraminifers. The deposition of silicious materials (tephra) due to this eruption might have provided an opportunity for benthic foraminifers to increase their population subsequently. From ca. 700 yr B.P. (~1,250 A.D.) mangroves declined, as indicated by lower frequencies of pollen grain in samples from 30 cm deep upward. It occurred simultaneously with the deposition of coarser sediment and the increase of benthic foraminifer abundance. Interplay of anthropogenic activities, strengthening ENSO cycle, and lowering erosion base level might have been responsible for these environmental changes.