Oligocene Cyclic Sedimentation Deduced from Taphonomic Analysis of Molluscs in Lacustrine Deposits of the Pematang Group, Pesada Well, Central Sumatra Basin

The Oligocene cycle of Pesada Well, Central Sumatra Basin, Indonesia is composed of a deepening-upward series of depositional cycles in a lacustrine environment affected by oscillations of the water level. Taphonomic analysis of gastropod molluscs was used to interpret the cycle architecture of the Brown Shale (Pematang Group). Four types of shell concentrations were identified. The early transgressive deposit has a distinct erosion surface at the base, contains concretions, is formed of coarse-grained sediment with abraded and broken shells, and is interpreted as reworked deposits. The late transgressive deposit contains a hiatal concentration formed by continuing lake level rise, with many complete shells preserved in life position. The maximum transgressive deposit has complete shells in life position or that have been transported, as well as juvenile molluscs and broken shells. The early regressive deposit contains alternating shell-rich and shell-poor layers. Since the lacustrine system shows no tectonic effects and also no marine influenced indications, the seven sedimentary cycles identified in the Pesada Well are likely to have been affected by oscillations between monsoonal and dry periods

SINGLE CHANNEL SEISMIC APPLICATION FOR GAS CHARGED SEDIMENT RECONNAISSANCE IN GEOHAZARD STUDY OF PORT CONSTRUCTION AT WETLAND AREA

Gas charged sediment as a one of parameter for geohazard study in infrastructure especially in swamp area. Instability of sediment layer for exampel subsidence and landslide result in geohazard potention that caused by gas charged sediment. Seismic single channel can be used to identufy gas charged sediment location. Seabed morphology is collected from bathymetry and tidal survey. From seismic profile interpretation shows gas charged sediment indication in Line A and Line B. That indication emerged by presence of acoustic turbid zone and acoustic blanking. Line A and Line B location will be spotlight in next geotechnic port construction study

Simple Statistical Testing on Existing Data of Core 39 KL SO189/2 to Reveal its Correlation Towards Sea Surface Temperature Variation

Several paleotemperature proxies using marine core sediment data have been developed and well-proven, but they need excellent laboratory handling and destructive tools. Spectrophotometer and Multi-Sensor Core Logger (MSCL) is considered rapid and non-destructive tools compared to other climate proxies. This paper enhances the correlation between existing data of spectrophotometer, MSCL, and sea surface temperature (SST) of the sediment core 39 KL from SO189/2 through a statistical test. The dataset is processed using interpolation, Pearson correlation, and K-means clustering. Pearson correlation reveals a strong correlation between spectrophotometer, MSCL, and SST. K-means clustering points out that SST is shifting from relatively colder to warmer. This study also tries to understand the source of four tephra and one terrigenous layer. It can be concluded that the spectrophotometer and MSCL have a positive correlation to SST variation. Keywords: statistical approach, existing data of SO189/2, spectrophotometer, Multi-Sensor Core Logger, sea surface temperatureBeberapa proksi paleotemperature menggunakan sedimen inti laut telah dikambangkan dan terbukti baik, namun membutuhkan penanganan laboratorium yang bagus dan bersifat destruktif. Spektrofotometer dan Multi Sensor Core Logger (MSCL) relatif lebih cepat dan tidak destruktif. Makalah ini membahas hubungan antara spektrofotometer, MSCL, dan temperature muka laut (SST) berdasarkan data sedimen inti 39 KL dari SO189/2 melalui pendekatan statistik. Data diolah menggunakan metode interpolasi, korelasi Pearson, dan kluster K-means. Korelasi Pearson menunjukkan korelasi kuat antara spektrofotometer, MSCL, dan SST. Kluster K-means menunjukkan pergeseran SST dari kondisi yang lebih dingin ke lebih hangat hubungan Stufi ini juga mencoba untuk memahami sumber 4 lapisan tefra dan 1 lapisan mineral terrigenous. Melalui studi ini, dapat disimpulkan bahwa spektrofotometer dan MSCL mempunyai korelasi positif terhadap variasi SST.Kata Kunci: Pendekatan statistik, Data existing SO189/2, spektrofotometer, Multi Sensor Core Logger, Suhu Permukaan Lau