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PB RATIO ANALYSIS OF FORAMINIFERA TO OBSERVE PALEOCEANOGRAPHIC CHANGES DURING HOLOCENE IN ARAFURA SEA
Get PDFArafura Sea is influenced by several climatic dynamics, it is also a part of the coral triangle that provides most of marine organism diversity of the world. Therefore, this area is an important waters that impact the climatic dynamic so its paleoceanographic changes need to be understood. For that, we analyzed the foraminiferal PB ratio from marine sediment core ARAFURA-24 with a core length of 179 cm, collected from 47.4 m water depth, combined with that of Aru-07, taken from 276 m water depth (core length 152 cm). Both sediment cores were collected from the Arafura Sea using a gravity corer on board Geomarin III. ARAFURA-24 was sub-sampling in every 20 cm interval, while Aru-07 had been prepared in every 10 cm interval. PB Ratio values from ARAFURA-24 and Aru-07 ranged from 0,56% - 7,43% and from 29,89% to 82,66%, respectively. The age model was reconstructed by 14C radiocarbon dating derived from organic sediment, combined with tie points of PB ratio records. The result indicates that ARAFURA-24 has been sedimented since the last 9.7 kyr BP. PB ratio records reveal three maximum sea level rises, which are before 7.4 kyr BP, at 5.86 kyr, and after 3 kyr BP (approximately at 2 kyr BP at Aru-07). From the age model reconstruction, sedimentation during the last 3 kyr BP was relatively slower than that in the older period. It can be concluded that the foraminiferal PB ratio during Late Holocene was not significantly impacted by sedimentation rate (hence detrital influence), in contrast, during Mid-Holocene detrital influence had more impact on the PB ratio record
SPATIAL DISTRIBUTION OF CHLOROPHYLL-A AND NUTRIENTS IN THE TENGAH ISLAND, KARIMUNJAWA INDONESIA
Get PDFTengah Island is located between Sintok Island and Cilik Island in Karimunjawa, Jepara Regency, Central Java. Tengah Island is one of the zones for the use of marine tourism, which has the allure of attractive spots for snorkeling and diving for tourists. Coral reefs require chlorophyll-a, which is in this case produced by zooxanthellae, as a photosynthetic pigment. The chlorophyll-a concentration is influenced by many factors, including nutrients and environmental parameters. This study aims to see the spatial distribution of chlorophyll-a on Tengah Island and its relationship to nutrients, including ammonium, phosphate, and nitrate, as well as environmental parameters, namely Total Suspended Solid (TSS), salinity, pH, Dissolve Oxygen (DO), temperature, and brightness. Chlorophyll-a is analyzed using the APHA standard (2005), while nutrient analyses for ammonium, nitrate, and phosphate employ the UV-Vis spectrophotometer and Nessler reagent, the APHA 4500-No.3-B (2017), and the APHA 4500-P B, C (2017), respectively. TSS is obtained from Sentinel-2A data processing. The correlation between each dataset was carried out by a method of statistical analysis called Principal Component Analysis (PCA). The results showed that chlorophyll-a had a close relationship with ammonium (r=0.826), brightness (r=0.492), and TSS (r=-0.979). The highest chlorophyll-a concentration of 1,063 μg/L was obtained at Station 1, which is the jetty area and the closest to the mainland. This finding is supported by maximum ammonium, sourced from domestic waste and microbial activity, and good brightness, required by chlorophyll-a for photosynthesis processes
STATISTICAL PARAMETERS ANALYSIS OF SEDIMENT GRAIN SIZE FROM RAYA RIVER BENGKAYANG REGENCY, WEST BORNEO
Get PDFThe study of the statistical analysis parameters of grain size in the waters of Sungai Raya was carried out in order to understand the characteristic of the sediment in the river and coastal areas. The grain size by sieving method, and analyze the statistical parameters including the average grain size, sorting, skewness, and kurtosis. Sediment samples were acquired from six stations with each station consisting of three sampling points representing river west bank, river midstream, river east bank, and the coastal area consisting of five stations. The results of the sediment analyses showed that the average grain size in the river ranges from 1.23 to 2.77 mm, and on the beach area is between 1,52 - 2,59 mm, classified as fine sand, medium sand, very fine sand, and coarse sand with predominant fine sand in all stations. The results of the statistical parameter analysis of the grain size of the bottom sediment in the waters of Sungai Raya exhibit the average diameter value ranging from 1.23 to 2.77 mm, classified as fine sand to medium sand. This value indicates that the type of sediment in this location is dominated by silt with grain sizes ranging from < 0.05 - 0.002 mm. The sorting value ranges from 0.14 to 1.59 mm, categorized into moderately sorted, moderately well-sorted, very well sorted, and poorly sorted classes. The average value of skewness is 2.17 with the classification of the bed load being very fine and kurtosis value ranges from 0.72 to 1.67 indicates the classification in these waters is platycuric, mesokurtic, leptokurtic, and very leptokurtic. These finding concluded that in the study area there is a variation in the angularity of the sediment grains due to the different hydrodynamic processe
ASH LAYERS FROM SOUTH ANDAMAN SEA: PROBABLY SOURCED FROM TOBA CALDERA
Get PDFDeep Sea sediment core PC-1 from the South Andaman Sea (7 ̊19.85' N; 94 ̊ 39.26' E; in East Andaman Basin) below the water depth of 3144 m contain discrete ash layers at various depths. According to morphological study, these ash layers contain glass shards of different varieties i.e. Type-I, Type-II, Type-III, Type-IV and Type-V and it is comparable to glass shards of Toba volcanic reported from other parts of the world. This observation is also supported on the basis of relative biostratigraphic datum observed in the core PC-1. The Layer-A (56 cm thick) at 210 cm bsf is just above the biostratigraphic datum of ca. 0.12 Ma, correspond to Youngest Toba Tuff (YTT), followed by Layer-C belongs to Middle Toba Tuff (MTT) and Layer-D inferred as Oldest Toba Tuff (OTT). This interpretation is further supported by the geochemical data obtained from the EDX analysis, which suggest high silica and alkali contents of rhyolitic composition. Hence, geochemical composition, morphology and biostratigraphic data of these discrete tephra layers show identical characteristics to the products of Toba eruptions, including YTT, MTT and OTT
IDENTIFIKASI PIPA BAWAH LAUT MENGGUNAKAN DATA GEOMAGNET, PERAIRAN BALIKPAPAN, KALIMANTAN TIMUR
Get PDFTransmisi gas dari sumur produksi melalui pipa bawah laut menuju titik distribusi merupakan hal yang sangat penting. Kebutuhan akan gas alam yang sangat tinggi seringkali mendorong pemasangan jaringan pipa gas baru begitupun ketika terjadi gangguan terhadap jaringan pipa yang lama. Pemasangan jaringan pipa baru membutuhkan informasi mengenai lokasi jaringan pipa terpasang. Identifkasi jaringan pipa bawah laut dapat dilakukan dengan survei magnetometer dan menerapkan pengolahan data yang dapat mempermudah identifikasi, tahapan pengolahan data akan dilakukan pada rute pipa bawah laut di Perairan Balikpapan untuk mengidentifikasi keberadaan pipa bawah laut yang sudah terpasang. Metode pengolahan data dilakukan dengan analisis signal sehingga jalur pipa gas bawah laut dapat teridentifikasi dengan lebih baik. Data magnet di Perairan Balikpapan dapat mengidentifikasi setidaknya 4 (empat) jalur pipa gas bawah laut terpasang. Penggunaan metode analisis sinyal memberikan gambaran yang lebih jelas keberadaan pipa gas bawah laut
MARINE GEOMAGNETIC ANOMALY BELT AND ITS RELATIONSHIP TO THE REMNANT ARCS IN THE NORTHWESTERN JAVA SEA, INDONESIA
Get PDFThe continuous marine geomagneticsurvey within a timeintervalof1-secondsampling and a precision of 0.1 nT was conducted in the northwestern Java Sea to identify and interpret the general trend of total marine magnetic anomalies and the possibility related to thegeological resourcepotential. These magnetic data were then processed according to the formula corrected and applied to marine magnetic data. The total marine magnetic anomalies of the northwestern Java Sea indicate a well-defined lateral trend belt of anomaly contours. Anomalies are divided into four delineation zones: Zones I, II, III, and IV. A preliminary analysis of these anomalies led to the interpretation, reflecting the residual of a slightly east-west trending geological body underneath.Examination of magnetic anomalies suggests Zone I and IV characterize a basinalarea, Zone II depicts a granitic belt, and Zone III describes a Cretaceousmagmatic arc system in the east that extends from Middle Java across the Java SeathroughSouthern Kalimantan. These magnetic anomalies seem to coincide with the free air gravity anomalies data derived from TOPEX satellite data.
