Paleoenvironmental Reconstructions using Organic Source Indicators: A Summary of Examples from Sri Lanka

The qualitative and quantitative analysis of sedimentary organic matter (i.e., the residue of past biota) provides integrated histories of marine and continental past life and paleoenvironmental /paleoclimatic changes. Organic geochemical investigations are possible by combining (i) bulk properties such as elemental compositions, stable isotope ratios, and Rock-Eval pyrolysis data, and (ii) biomarker molecular compositions such as n-alkanes, sterol, and polycyclic aromatic hydrocarbons compositions. The analytical approaches described in this overview illustrate the published examples of lacustrine and marine organic geochemical studies in Sri Lanka. In summary, the Jurassic Andigama and Tabbowa Basins provide different sources of organic matter, followed by availability of nutrient for algal growth and the amount of land runoff to the basins. Rock-Eval analysis of the Cretaceous to Paleogene sedimentary rocks in the offshore Mannar Basin reveal the presence of gas-prone land-plant organic matter mainly and minor oil-prone algal organic matter. The amounts and types of organic matter variations in Bolgoda Lake sediments indicate changes in Holocene sea-level, coastal geomorphology, and continental climates during the last 7,000 years. In future directions, applications of novel organic geochemical proxies and understanding of original biologically synthesized materials in tropics would improve interpretations of paleoenvironmental changes. Besides, local and regional paleoclimatic proxy and model studies would refine future paleoenvironmental reconstructions in Sri Lanka

Qualitative mineralogical analysis of Barracuda exploration well in the offshore Mannar Basin (the Indian Ocean) using FTIR and XRD techniques

The Mannar Basin plays a vital role in petroleum exploration in Sri Lanka, and its Barracuda exploration well was drilled up to 4206 m in depth. The objective of the current study is to identify mineralogy using Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) analyses. The FTIR and XRD analyses confirm the presence of quartz, feldspar, clay minerals (e.g., kaolinite, montmorillonite), calcite, and hematite in all marlstone and mudstone samples. These sedimentary rocks can be identified as potential petroleum source rocks in the Mannar Basin. Quartz, carbonate, and hematite cementations are directly reduced porosity and permeability, and thus primary migration of hydrocarbons from potential source rocks. Clay minerals act as a seal for hydrocarbon migrations in the Mannar Basin. A variety of dominant clay mineral assemblages allows the reconstruction of several paleoclimatic chronozones in warm/wet and arid climates. In contrast, feldspar dissolution promotes the primary migration of hydrocarbon from potential petroleum source rocks. Consequently, this study concluded that common minerals such as quartz, carbonate, and hematite are associated with the trapping and binding processes of hydrocarbons

Characteristics of Lowland Tropical Peatlands: Formation, Classification, and Decomposition

Tropical peatlands occur mostly in coastal lowlands, and it can be considered as larger sinkers of carbon and important ecosystem services for water resources, bio-resources and biodiversity. This article summarised characteristics, formation and classification of tropical lowland peatlands. Tropical peatlands cover about 11% of the global peatland resource (441,025 km2 in area) and the estimation value can be changed with including all histosols and shallow organic soils. Tropical coastal peatlands were predominantly developed during the middle to late Holocene (between 3,500 to 6,000 years BP) under the wet conditions generated after the stabilisation and regression of middle Holocene sea-level highstands. Hydrology is a fundamental factor to the formation and function of tropical peatlands. There is no specific definition for the peatlands based on available references. The available definitions can be broadly divided into authoritative and scientific definitions. The authoritative definitions depend on specific uses and applications, while scientific definitions depend on field observations and experimental design/analytical methods. Tropical peatlands store abundant organic matter. However, the recent anthropogenic activities enhance the emission of stored carbon as greenhouse gasses such as CH4 and CO2

Mechanochemical Conversion of Ilmenite to Synthetic Rutile: A Green Technology

Titanium minerals such as ilmenite (FeTiO3), leucoxene (altered ilmenite) and rutile (TiO2) are economically imported in the global heavy mineral market. In this regard, high quality ilmenite, leucoxene, and rutile concentrates can be directly used as feedstock for TiO2 pigment production. However, lower quality ilmenite requires prior processing to titanium slag or synthetic rutile.Chemical routes such as Sulphate and Chloride processes are traditionally followed to prepare synthetic rutile from ilmenite. However, chemical methods yield environmentally unfriendly byproducts such as iron(III) chloride and acidic iron(II) sulphate. Consequently, the current study is focussed on upgrading Sri Lankan ilmenite using crystalline vein graphite and commerciallyavailable sulphur as reducing agents. In this mechanochemical method, the ball milling induced Sulphurisation and carbothermic reductions were examined using X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and particle size analysis. XRF results suggest that raw ilmenite was characterised by over 95% of FeTiO3, ~2% of SiO2, ~1% of Al2O3 and the rest compensated by other minor elements. Ilmenite was mixed with a combination of sulphur and vein graphite in three ratios by weight as 1:1, 2:1 and 4:1. These mixtures were uniquely milled for 4 hours and 6 hours each. The reduction in the intensity of sulphur and graphite peaks and the broadening of ilmenite peaks in XRD spectra obtained after milling. It indicates a possible dissolution of sulphur and graphite into the ilmenite structure through cleavage planes. The incorporation of additives into the ilmenite structure was confirmed using the SEM images. Pseudorutile peaks observed in the XRD spectra of milled samples. Each sample was separately annealed at 800o C, 1,000o C and 1,200o Crespectively. Consequently, the effective temperature was determined to be 1,000o C. Each ratio produced similar results and the optimum ratio was obtained at 4:1. The pseudorutile peaks were disappeared whereas, brookite and rutile peaks appeared in the XRD spectra of the annealed samples. It was concluded that mechanical attrition applies beneficial outcome on the diminishingtemperatures of ilmenite reduction. Consequently, this environmentally friendly method could be applied to convert ilmenite to synthetic rutile.Keywords: Ball milling and isothermal annealing, Ilmenite, Sulphur and vein graphite, Environmentally friendl

Qualitative Mineralogical Analysis of Deep-Sea Sediments Based on the Lithology in the Offshore Mannar Basin by using FTIR and XRD Techniques

The Mannar Basin, with a total area of 45,000 km2, is a key sedimentary basin for petroleum prospecting in Sri Lanka. It stretches from southeast India to southwest Sri Lanka and the basin is made primarily of Precambrian high-grade metamorphic rocks. In 2011, Cairn Lanka Private Limited (Cairn) drilled three exploration wells (Dorado, Dorado North, and Barracuda) and one exploration well (Wallago) in the recent petroleum exploration in Mannar basin. Source rock quality and maturity are important factors to consider when evaluating oil and gas potential. As a result, mineralogy plays an important role in the geochemical characterization of source rocks. In this study sediment samples of Barracuda exploration well in Mannar basin were collected from Petroleum Resources Development Secretariat in Sri Lanka (PRDS) at depth ranging from 2,260 to 4,740 m, and the samples were cleaned before analysis to eliminate drilling mud. The powdered material was made by crushing the cleansed sediment samples with a motor and petal, then screening them through a 53 µm standard sieve. After that sediment samples were analyzed through Fourier Transformation Infrared Spectroscopy (FTIR) and X-Ray Diffractometer (XRD) to obtained the available mineralogy qualitatively. The observed data were interpreted based on sample age, depth, and lithology, as well as their impact on the Mannar basin. According to previous research, the detected FTIR band wavelengths were used to determine the accessible mineralogy of the samples. The XRD peaks were determined using Crystal Impact Match 3.0 software and literature. The presence of quartz, feldspar, kaolinite montmorillonite, and calcite in the entire marlstone and mudstone samples is confirmed by FTIR analysis. The XRD analysis revealed that calcite, and quartz are dominant in marlstone with black carbon sediment samples and marlstone sediment samples. Quartz, illite, and calcite dominate in argillaceous marlstone sediment samples. Illite, montmorillonite, kaolinite, and calcite are dominant in slightly calcareous mudstone sediment samples. Quartz overgrowth and cementation were caused by the presence of quartz. In the Mannar Basin, quartz cementation can reduce reservoir rock porosity and have an effect on permeability by increasing rock brittleness and occupying pore space. Overgrowths of quartz reduce reservoir porosity and permeability. Feldspar alteration changes porosity and permeability, whereas dissolution increases secondary porosity and permeability of source rock in the basin. Clay minerals have an impact on hydrocarbon formation, accumulation, migration, and reservoir quality in the basin. Also, tectonics and sedimentation modify the abundance and crystal structure of clay minerals. Furthermore, the presence of carbonate minerals and hematite is responsible for the cement's creation. Calcite cement has an effect on the basin's reservoir quality, while hematite cement is uncommon. Keywords: Mannar basin, Sediment, Mineralogy, FTIR, XR

A FUZZY EXPERT SYSTEM FOR BUSINESS INTELLIGENCE

Business Intelligence (BI) is recognized as an increasingly important support for business decision making in emerging business environment, where a huge amount of data is growing fast and scattered around. Explicit knowledge can be presented formally and capable of effective (fast and good quality) communication of data to the user where as commonsense knowledge can be represented in informal way and further modeling needed for BI. Acquiring useful Business Intelligence (BI) for decision-making is a challenging task in dynamic business environment. In this paper we present an approach for modeling commonsense knowledge in Business Intelligence. A fuzzy expert system based on principal component analysis (PCA) and statistical fuzzy inference system for modeling Business Intelligence in commonsense knowledge is introduced in, which enables holistic approach for disaster management. This paper describes one such approach using classification of human constituents in Ayurvedic medicine. Evaluation of the system has shown 77% accuracy. Key words: Business Intelligence, Statistical inference system, Common sense knowledge, Principal component analysis and Ayurvedic medicineFor full Paper: [email protected]

Reconstruction of Quaternary Environmental Changes on Eastern Coast of Sri Lanka.

Coastal sedimentary archives are important to recognise the past dynamics of environmental changes and climate variability. The current study describes paleoenvironmental changes in the eastern coast of Sri Lanka. A core sample (length=10 m) was collected from a stagnant shallow water coastal body next to the Koddiyar Bay. The sampling site is not presently connected to the Indian Ocean through the Koddiyar Bay. Sediment samples were sliced into 5 cm intervals, and oven-dried at 60º C for 48 hours before geochemical analyses. Weight percentages of Total carbon (TC), total nitrogen (TN) and total sulphur (TS) were measured using CHNS/O elementary analyser. Mineral phases of the sediments were determined using X-ray diffractometry (XRD). In the lower sedimentary succession, TC (range from 0.25% to 0.32%) and TS (range from 0 to 0.54%) are low from the depth of 460 cm to 205 cm. These values can suggest a low productive and oxic depositional environment. However, TC and TS values are slightly increased in the regions of 415 cm to 375 cm. This organic matter rich brackish chronozone can probably indicate short-livedenvironmental changes such as paleo tsunami or saltwater intrusion. In the upper sedimentary succession, TC (range from 0.32% to 7.37%), TN (range from 0.1% to 0.37%), and TS (range from 0.54% to 3.19%) values are gradually increased in the depth from 210 cm to the Recent sediments. It can probably indicate anthropogenic activities in the watershed. In addition, this upper sedimentary succession is characterised by the deposition of organic matter rich sediment under the anoxic to oxygen-poor conditions. According to XRD results, clay minerals such as illite and smectite are abundant throughout the core. Pyrite can also be identified as an abundant mineral in upper sedimentary succession suggesting that bacterial sulphate reduction and formation of sedimentary pyrite. In conclusion, a clear unconformity can be identified for the major environmental change at 210 cm in depth may be due to land degradation in the region.Keywords: Carbon burial, Sediments, Depositional environment, Paleo tsunam