OSTRACODA FROM SUBSURFACE SEDIMENTS OF KARIMATA STRAIT AS INDICATOR OF ENVIRONMENTAL CHANGES

Karimata Strait is a part of Sunda Shelf connected South China Sea with Malacca Strait, Indian Ocean and Java Sea. This shelf was a large Sunda Land that has been detected by many evidences as records of various paleo-environments. The purpose of this study is to recognize the characteristic community of ostracoda related to the environmental history of this shelf. Three selected cores sediments represented east (A), middle (B) and west (C) parts of Karimata Strait were used for Ostracoda based on standard method on micropaleontology. Additional method was applied of SEM-EDX analysis to abnormal specimens. The result shows that there are 43 species of ostracoda belonging to 34 genera identified in the study area. The highest number of ostracoda is found in Core B, in the middle part of the strait, and the lowest value belongs to the Core A that close to the land of Kalimantan. Several genera of Ostracoda were documented in all cores: Actinocythereis, Cytherella, Cytherelloidea, Keijia, Keijella, Hemicytheridea, Hemikrithe, Neocytheretta, Neomonoceratina, Loxoconcha, Pistocythereis, Stigmatocythere and Xestoleberis. Vertically, ostracoda are mostly found in the upper part of the cores and decrease or disappear in the lower part of Cores A and C where dominated by black organic materials. It may relate to a wide swampy area before the last sea level rise as part of the history of the SundaShelf about 15,000 years ago. Some major elements (C, CaO, Al2O4, FeO, SiO2, MgOdan SO3 covered or filled abnormal specimens that can provide additional information about environmental changes in the study area, such as Carbon may relate to charcoal from land of Kalimatan and Sumatera Keywords: Ostracoda, subsurface sediment, EDX, environmental changes, Karimata Strait Selat Karimata merupakan bagian dari Paparan Sunda menghubungkan Laut China Selatan dengan Selat Malaka, Samudera Hindia, dan Laut Jawa. Paparan ini merupakan sebuah Dataran Sunda yang luas yang terdeteksi dari bukti-bukti sebagai rekaman berbagai lingkungan purba.Tujuan dari studi ini adalah untuk mengetahui karakteristik komunitas ostracoda berkaitan dengan sejarah lingkungan paparan ini. Terpilih tiga sedimen pemercontoh inti mewakili bagian timur (A), tengah (B) dan barat (C) Selat Karimata digunakan untuk studi Ostracoda berdasarkan metoda standar pada mikropaleontologi. Metoda tambahan adalah aplikasi SEM-EDX terhadap spesimen abnormal. Hasil menunjukkan bahwa di daerah penelitian teridentifikasi 43 spesies ostracoda termasuk dalam 34 genera. Jumlah ostracoda tertinggi ditemukan di Core B dari bagian tengah selat dan terendah di Core A yang berdekatan dengan daratan Kalimantan. Beberapa genera ostracoda ditemukan di semua sampel: Actinocythereis, Cytherella, Cytherelloidea, Keijia, Keijella, Hemicytheridea, Hemikrithe, Neocytheretta, Neomonoceratina, Loxoconcha, Pistocythereis, Stigmatocythere dan Xestoleberis. Secara vertikal, ostracoda umumnya ditemukan di bagian atas dari core dan menurun atau menghilang di bagian bawah Core A dan C yang di dominasi oleh material organik berwarna hitam. Hal ini kemungkinan berkaitan dengan daerah rawa yang luas dan sebelum muka laut naik terakhir pada sejarah Paparan Sunda sekitar 15.000 tahun yang lalu. Beberapa zat kimia (C, CaO, Al2O3, FeO, SiO2, MgO dan SO3) menutupi atau mengisi spesimen abnormal dapat memberi informasi tambahan tentang perubahan lingkungan di daerah penelitian, seperti karbon mungkin berkaitan dengan arang dari daratan Kalimantan dan Sumatera. Kata kunci: Ostracoda, sedimen bawah dasar laut, EDX, perubahan lingkungan, Selat Karima

THE CORRELATION BETWEEN BENTHIC FORAMINIFERA AND SEDIMENT TYPES OF SOUTH MAKASSAR STRAIT

South Makassar Strait is located between Kalimantan and Sulawesi Islands that is an important oceanographic pathway connecting between the Pacific and Indian oceans. This area is a part of sedimentary basin that has specific seabed morphology and sediment characteristics, including foraminifera as a component of sediments. The purpose of this study is to determine community structure of benthic foraminifera related to sediment characteristics. This study used 20 top core sediment samples from water depth between 200 and 1500 m. There are identified 38 species of benthic foraminifera and some of them are characterized the study area: Anomalinoides colligerus, Lenticulina suborbicularis, Planulina wuellerstorfi, , and Pseudonodosaria discrete. The diversity index is categorized as moderate values (1.0=H'= 3) and the average of evenness values is about 0.79. The dominance values are less than 0.5 indicate that there is no dominant species in the study area. In relation to sediment characteristics, it shows that the high abundance of benthic foraminifera occurs in sediment type of silty sand and sandy silt. Moderate abundance appears in sand following by low abundance in silt and sandy silt sediment types. Keywords: benthic foraminifera, community structure, sediment types and Makassar Strait Makassar bagian selatan terletak diantara Pulau Kalimantan dan Sulawesi yang merupakan jalur oseanografik yang penting menghubungkan Samudera Pasifik dan. Wilayah ini merupakan bagian dari cekungan sedimen yang mempunyai morfologi dasar laut dan karakteristik sedimen tertentu termasuk foraminifera sebagai komponen sedimen. Tujuan dari penelitian ini adalah untuk mengetahui struktur komunitas foraminifera bentik dalam kaitannya dengan tipe sedimen dasar laut. Penelitian ini menggunakan 20 sampel sedimen bagian atas dari pemercontoh inti pada kedalaman antara 200 dan 1500 m. Ada 38 spesies foraminifera bentik dan beberapa diantaranya mencirikan daerah penelitian: Anomalinoides colligerus, Lenticulina suborbicularis, Planulina wuellerstorfi, dan Pseudonodosaria discrete. Indeks keanekaragaman termasuk dalam kategori sedang (1,0=H’=3) dan nilai rata-rata keseragaman sekitar 0,79. Nilai dominasi lebih kecil dari 0,5 itu menandakan tidak ada spesies yang dominan pada lokasi penelitian. Terkait dengan karakteristik sedimen menunjukkan bahwa kelimpahan foraminifera bentik tinggi terdapat pada jenis sedimen pasir lanauan dan lanau pasiran. Kelimpahan sedang ditemukan pada jenis sedimen pasir diikuti kelimpahan rendah yang dijumpai pada sedimen lanau dan lanau pasiran. Kata kunci: foraminifera bentik, struktur komunitas, jenis sedimen, Selat Makassar

LAND-SEA INTERACTIONS IN COASTAL WATERS OFF NE KALIMANTAN: EVIDENCE FROM MICROFAUNAL COMMUNITIES

Microfauna (ostracoda and foraminifera) as component of sediments has been used to detect the dynamics of sea floor condition in NE Kalimantan, particularly off Nunukan and Sebatik Islands. In general, the microfaunal components tend to increase (both number of species and specimens) from near shore to the open sea. The microfauna occur rarely at locations surrounding the islands due to high content of plant remains from the land. The marine origin of microfaunas occurs very abundantly in the inner part of the study area between Tinabasan and Nunukan Islands. This finding is interested due to their occurrence as unusual forms: brownish shells, broken and articulated ostracod carapaces. Additional interested findings are: the incidence of abraded test of Elphidium, the occurrence of dominant species of both ostracoda and foraminifera at some stations; various morphological forms of foraminiferal genus, Asterorotalia that reaches about 1% and distributed in the open sea. The various unusual forms may relate to the dynamics of local environmental changes such as postdepositional accumulation in the sediment, biological activities, and drift currents from open sea to landward. Keywords: Ostracoda, Foraminifera, North East Kalimantan, land-sea interaction Mikrofauna (ostracoda dan foraminifera), sebagai komponen sedimen dapat digunakan untuk mendeteksi dinamika kondisi dasar laut di Kalimantan Timur, tepatnya di sekitar Pulau Nunukan dan Sebatik. Secara umum, komponen mikrofauna cenderung bertambah (baik dalam jumlah spesies maupun spesimen) dari perairan sekitar pantai ke arah laut lepas. Mikrofauna yang ditemukan sangat jarang di lokasi sekitar pulau-pulau disebabkan oleh keterdapatan sisa-sisa tanaman dari daratan. Mikrofauna asal lautan ditemukan sangat melimpah di bagian dalam daerah penelitian antara Pulau Tinabasan dan Nunukan. Temuan ini sangat menarik karena adanya bentukan abnormal: cangkang berwarna kecoklatan, rusak dan cangkang ostracoda berbentuk tangkupan. Temuan tambahan yang juga menarik adalah: keterdapatan cangkang Elphidum yang rusak, keterdapatan beberapa spesies ostracoda dan foraminifera secara dominan di titik lokasi tertentu, dan kenampakan morfologi yang bervariasi dari genus foraminifera, Asterorotalia, yang mencapai 1% dan tersebar di laut lepas. Berbagai bentukan abnormal tersebut kemungkinan berkaitan dengan dinamika kondisi lingkungan setempat seperti akumulasi setelah pengendapan dalam sedimen, aktivitas biologis dan alur arus dari laut terbuka kearah daratan. Kata kunci: ostracoda, foraminifera, Kalimantan Timur, interaksi daratan-lauta

THE CHARACTERISTIC OF DEEP SEA FORAMINIFERAL COMMUNITY IN TOMINI BAY, SULAWESI

A total of 14 sediment samples from Tomini Bay, Sulawesi were used for this study as a component of sediment. The samples were carried out by using a gravity corer at water depth range between 600 and 1400 m. This study was a part of mapping activity on marine geology and geophysics during the first cruise of R/V Geomarin III in 2010. The purpose of this study was to examine the subsurface geology related to the potency of energy and mineral resources. Top core sediment samples were washed through 0.063mm opening sieve and then dried in an oven.  About maximum 300 foraminiferal specimens were picked from every dried washed residue sample to separate them from other particles under a binocular microscope with brush and water. The result showed that most samples were dominated by planktonic foraminifera (>90%), such as Globorotalia menardii, Orbulina universa, Globigerinoides ruber and others as typical of deep sea sediments.  On the other hand, benthic foraminifera was found less than 10% that was represented by Cibicidoides wuellerstorfi, Ceratobulimina pacifica, Pyrgo sp., Bolivinita quadralatera, Uvigerina peregrina, etc. The characteristic of deep sea foraminiferal community of this area may be used for interpreting environmental deposition in the adjacent areas that is useful for petroleum exploration. Keywords: foraminifera, deep sea, Tomini Bay, Sulawesi

Ostracoda from the Java Sea, West of Bawean Island, Indonesia

Ostracod faunas from surface and core sediment samples from west of Bawean Island, Java Sea, Indonesia have been studied- quantitatively. A total of 113 species including seven new species, 1 new subspecies and 16 species which remain in open nomenclature were recorded. The following new species and subspecies were erected: Polycope baweaniensis sp. nov., Cytherella javaseaense sp. nov., lAglaiocypris susilohadii sp. nov., Loxoconcha wrighti sp. nov., Loxoconcha ismailusnai sp. nov., Keijia tjokrosapoetroi sp. nov., Keijella carriei sp. nov. and Foveoleberis cypraeoides baweani ssp. nov. Ostracod faunas from surface and core sediment samples from west of Bawean Island, Java Sea, Indonesia have been studied- quantitatively. A total of 113 species including seven new species, 1 new subspecies and 16 species which remain in open nomenclature were recorded. The following new species and subspecies were erected: Polycope baweaniensis sp. nov., Cytherella javaseaense sp. nov., lAglaiocypris susilohadii sp. nov., Loxoconcha wrighti sp. nov., Loxoconcha ismailusnai sp. nov., Keijia tjokrosapoetroi sp. nov., Keijella carriei sp. nov. and Foveoleberis cypraeoides baweani ssp. nov. The species spectra of the study area show a close biogeographical relationship with other assemblages from the Malacca Strait and the southern part of South China Sea. A moderate affinity with eastern part of Indonesia including Gulf of Carpentaria, the Solomon Islands and Arafura Sea is probably due to the presence of shelf break in the Banda Sea which has more than 5000 m depth. Changes in ostracod diversity and density from core samples of the study area were documented. The ostracod faunas on the upper part (at interval 0-60 cm) were more abundant and diverse than on the lower parts. This change and also variation in sedimentoiogical and geochemical data (such as texrural changes, abundance of calcareous ooliths, very low phosphorus and organic contents in some intervals of the cores), it is inferred that a stadia! period occurred in the study area. In certain areas during this period, this was indicated by the present of a oligohaline and less agitated environment On the basis of radiocarbon data from surrounding areas, it is suggested that this period was at about 10 ka ago

Ostracoda: objek alternatif untuk studi mikropaleontologi

Buku ini membahas materi persiapan penelitian ostracoda, ostracoda, klasifikasi dan identifikasi ostracoda, ostracoda dan kurun waktu geologi, serta peranan dan aplikasi ostracod

SEBARAN SPASIAL FORAMINIFERA DALAM KAITANNYA DENGAN KEDALAMAN LAUT DAN JENIS SEDIMEN DI TELUK BONE, SULAWESI SELATAN

Sebanyak 25 sampel sedimen dasar laut dari Teluk Bone bagian utara, Sulawesi Selatan telah digunakan untuk analisis foraminifera dalam kaitannya dengan jenis sedimen dan kedalaman. Hasil analisis diperoleh 97 spesies foraminifera bentik dan beberapa genera diantaranya mendominasi titik lokasi tertentu, seperti Amphistegina, Operculina, Heterolepa, Brizalina, Elphidium dan Quinqueloculina.Setiap genus mempunyai distribusi spasial tertentu sesuai habitatnya dengan beberapa anomali. Kisaran kedalaman daerah penelitian antara 23 dan 85 m dicirikan oleh kehadiran Amphistegina, Cibicides, Rotalia, Cavarotalia. Dalam kaitannya dengan kedalaman, sebaran foraminifera cenderung terakumulasi di sebelah timur daerah penelitian. Setiap satuan sedimen dicirikan oleh genus foraminifera tertentu. Kata kunci: foraminifera, distribusi spasial, kedalaman laut, jenis sedimen, Teluk Bone, Sulawesi Selatan A total of twenty five surface sediment samples from the northern part of Bone Bay, South Sulawesi were selected for foraminiferal study. The purpose of this study is to recognize spatial distribution foraminifera in relation with water depth and sediment types. There are 97 identified species, some ot them are dominant at certain sites, such as Amphistegina, Operculina, Heterolepa, Brizalina, Elphidium and Quinqueloculina. Each genus has certain spatial distribution as its habitat with some anomalies. The range of water depth is between 23 and 85 m that characterized by Amphistegina, Cibicides, Rotalia, Cavarotalia. In relation to water depth, the distribution of foraminifera tends to accumulate in the eastern part of the study area. Sediment unit is characterized by certain foraminifera genus. Keywords : Foraminifera, spatial distribution, water depth, sediment type, Bone Bay, South Sulawesi

ANALISIS PENTARIKHAN RADIOKARBON UNTUK PENENTUAN FLUKTUASI MUKA LAUT DI SEBELAH UTARA PULAU BANGKA

Salah satu metode penentuan umur absolut batuan, fosil, sedimen atau artefak adalah menggunakan pentarikhan radiokarbon (C14) dari material organik. Data umur tersebut dapat berguna untuk menunjang berbagai penelitian terkait dengan sejarah bumi dan kehidupan manusia. Tujuan dari tulisan ini adalah untuk melacak fluktuasi muka laut berdasarkan data umur sedimen bawah dasar laut di sebelah utara Pulau Bangka. Hasil analisis pentarikhan radiokarbon terhadap tiga sampel sedimen menunjukkan dua umur yang berbeda. Sedimen dari bagian bawah (70-80 cm) dibawah dasar laut telah diperoleh umur 15.050± 60 SM dan 15.250 ±850 SM. Rentang waktu ini termasuk dalam segmen 2 pada saat laut naik sedang dari kedalaman -114 ke -96 m dari muka laut saat ini. Sedimen dari bagian atas (30 cm) telah diperoleh umur 6.500 ± 360 SM pada saat muka laut mendekati posisi sekarang. Studi ini memperlihatkan fluktuasi muka laut di wilayah lokal di sekitar Pulau Bangka. Katakunci: pentarikhan karbon, muka laut, Pulau Bangka One method for absolute dating of rocks, fossils, sediments or artefacts is by using radiocarbon dating (14C dating) of organic materials. This age data can be useful for supporting various researches related to the history of earth and human being. The purpose of this paper is to trace the sea level fluctuation based on subsurface sediments from northern part of Bangka Island. The radiocarbon dating from three sediment samples has resulted two different age. Sediments at the bottom part of the core (70-80 cm) below seafloor have been dated at 15.050 ± 60 BP and 15.250± 850 BP. It belongs to segment 2 when sea rose moderately from -114 to-96 m of the present-day sea level. The sediment at the upper part (30 cm) has been dated at 6.500 ± 360 BP when sea level as close as present-day position. This study shows sea level fluctuation in the local area off Bangka Island. Keywords: radiocarbon dating, sea level, Bangka Islan

ABNORMAL MICROFAUNAL SHELLS AS EARLY WARNING INDICATOR OF ENVIRONMENTAL CHANGES SURROUNDING BERAU DELTA, EAST KALIMANTAN

A total of 25 sediment samples from surrounding Berau Delta, East Kalimantan have been used for microfaunal study. It is found some abnormal shells of ostracoda, foraminifera and other forms with darkish shells (black, dark green and dark brown). These forms were analyzed using SEM-Energy Dispersive X-ray spectroscopy (EDX or EDS) to know their chemical composition. The result shows that these abnormal forms composed of CaO, SiO2, C, FeO, Al2O3, K2O, and small amount of Na2O and Cl. They may derive from different sources: CaO and MgO from neutralized component during the environmental management to handle the Acid Mine Drainage (AMD). The other components may derive from coal ash during combustion process or other activities. From this result, the small amount (less than 5%) of abnormal shells may be used as early warning indicator of environmental changes in the study area. Keywords: abnormal microfaunal shells, chemical composition, Berau Delta. Sebanyak 25 sampel sedimen dari sekitar Delta Berau, Kalimantan Timur telah digunakan untuk studi mikrofauna. Ditemukan cangkang abnormal dari ostracoda, foraminifera dan spesimen bentuk lain dengan cangkang kegelapan (hitam, hijau tua dan coklat tua) Bentuk-bentuk ini kemudian dianalisa menggunakan SEM-Energy Dispersive X-ray spectroscopy (EDX or EDS) untuk mengetahui komposisi kimiawinya. Hasilnya menunjukkan bahwa cangkang-cangkang mikrofauna yang abnormal ini mengandung CaO, SiO2, C, FeO, Al2O3, K2O, dan sedikit kandungan Na2O dan Cl. Komponen ini kemungkinan mempunyai sumber yang berbeda: CaO dan MgO mungkin berasal dari bahan penetral selama pengelolaan lingkungan untuk mengatasi air asam tambang (AMD). Komponen lain berasal dari abu batubara saat proses pembakaran atau aktivitas lain. Jumlah cangkang abnormal yang sedikit (kurang dari 5%) ini kemungkinan dapat digunakan sebagai indikator peringatan dini adanya perubahan lingkungan di daerah penelitian. Kata kunci: cangkang mikrofauna abnormal, komposisi kimiawi, Delta Bera

ABNORMAL MICROFAUNAL SHELLS AS EARLY WARNING INDICATOR OF ENVIRONMENTAL CHANGES SURROUNDING BERAU DELTA, EAST KALIMANTAN

A total of 25 sediment samples from surrounding Berau Delta, East Kalimantan have been used for microfaunal study. It is found some abnormal shells of ostracoda, foraminifera and other forms with darkish shells (black, dark green and dark brown). These forms were analyzed using SEM-Energy Dispersive X-ray spectroscopy (EDX or EDS) to know their chemical composition. The result shows that these abnormal forms composed of CaO, SiO2, C, FeO, Al2O3, K2O, and small amount of Na2O and Cl. They may derive from different sources: CaO and MgO from neutralized component during the environmental management to handle the Acid Mine Drainage (AMD). The other components may derive from coal ash during combustion process or other activities. From this result, the small amount (less than 5%) of abnormal shells may be used as early warning indicator of environmental changes in the study area