Carbon isotopic equilibrium of the surface waters as a proxy for climate change through the last glacial/interglacial cycle in the Southwest Pacific

<p>Carbon-13 is a relatively understudied geochemical property in the world ocean. The Southwest Pacific, in particular, is devoid of δ¹³C data. This thesis therefore has two main objectives: to create a model to describe the modern distribution of δ¹³C around New Zealand (30-70°S, 140°E-150°W), and to describe changes in δ¹³C in a latitudinal transect of cores to the east and south of New Zealand. A model using multiple linear regression was created by comparing δ¹³C with potential temperature, salinity, density, and oxygen data. This model matches well with ship board δ¹³C measurements taken throughout the region. The resulting models were then compared to core top data to determine how well modern δ¹³C values compare to the Holocene, pre-industrial values. A new model, based on previous pre-industrial models, was created at much higher resolution to recreate the pre-industrial δ¹³C distribution. Core top values were found to be intermediate between Holocene and modern values. Down core δ¹³C data was split into six regions based on oceanographic conditions to determine what caused and how δ¹³C change occurred in the past. Data was run through 1000 iterations of a Monte Carlo simulation to determine a robust δ¹³C curve back through time. The biologic pump was found to dominate the δ¹³C levels in the region through iron fertilization and increased productivity in the polar zone. The LGM and deglacial δ¹³C values reflect greater influence on δ¹³Catm, suggesting that an increase in upwelling along the Antarctic coast and a possible strengthening of the westerly wind belt caused changes in ocean circulation throughout the region. The ACR and Early Holocene periods show good correlation with atmospheric CO₂ records, suggesting increasing temperatures may have increased productivity. The remainder of the Holocene to the present is mainly influenced by δ¹³Catm, suggesting relatively stable conditions in ocean and atmosphere.</p>

Carbon isotopic equilibrium of the surface waters as a proxy for climate change through the last glacial/interglacial cycle in the Southwest Pacific

<p>Carbon-13 is a relatively understudied geochemical property in the world ocean. The Southwest Pacific, in particular, is devoid of δ¹³C data. This thesis therefore has two main objectives: to create a model to describe the modern distribution of δ¹³C around New Zealand (30-70°S, 140°E-150°W), and to describe changes in δ¹³C in a latitudinal transect of cores to the east and south of New Zealand. A model using multiple linear regression was created by comparing δ¹³C with potential temperature, salinity, density, and oxygen data. This model matches well with ship board δ¹³C measurements taken throughout the region. The resulting models were then compared to core top data to determine how well modern δ¹³C values compare to the Holocene, pre-industrial values. A new model, based on previous pre-industrial models, was created at much higher resolution to recreate the pre-industrial δ¹³C distribution. Core top values were found to be intermediate between Holocene and modern values. Down core δ¹³C data was split into six regions based on oceanographic conditions to determine what caused and how δ¹³C change occurred in the past. Data was run through 1000 iterations of a Monte Carlo simulation to determine a robust δ¹³C curve back through time. The biologic pump was found to dominate the δ¹³C levels in the region through iron fertilization and increased productivity in the polar zone. The LGM and deglacial δ¹³C values reflect greater influence on δ¹³Catm, suggesting that an increase in upwelling along the Antarctic coast and a possible strengthening of the westerly wind belt caused changes in ocean circulation throughout the region. The ACR and Early Holocene periods show good correlation with atmospheric CO₂ records, suggesting increasing temperatures may have increased productivity. The remainder of the Holocene to the present is mainly influenced by δ¹³Catm, suggesting relatively stable conditions in ocean and atmosphere.</p>

Prospects of primary gold potential in southern Siberian platform based on study results for placer gold morphological and geochemical features

Data on geological structure and minerals of the southern Siberian platform are presented. Placer and primary gold occurrences widespread in this region are briefly characterized. Based on placer gold morphological and geochemical property studies using electron microscopy, its four types are revealed. Conclusions are made about potential primary sources of various placer gold types. Using retrospective data and based on the authors’ placer gold morphological and geochemical studies, Ust-Ilimskaya, Chernorechinskaya and Buraevskaya gold areas are characterized, their prospects for discovering primary gold deposits of various genetic types are determined.

Physical and Geochemical Investigation of Cross River Sand at Ozizza, Ndibe, Kpoghirikpo and Unwana, Afikpo-North Ebonyi State, South-East Nigeria

High strength, high hardness and very tough engineering material derived from geologically occurring minerals and processed into a tool that rubs or wears off by friction is regarded as an abrasive. Abrasives are produced in different forms and shapes and they afford good opportunities for precision scraping away or machining. In this empirical paper, effort is made in establishing a case for the production of abrasive tools that are formulated with silicon carbide and aluminium oxide as catalytic raw materials. These are locally found in the researchers’ locality a place that has many geological deposits of solid minerals. At each of Ozizza, Ndibe, Kpoghirikpo and Unwana beaches, eleven samples of sand were collected at random locations from the Cross River that is flowing through Ozizza down to Unwana for physical and geochemical investigation to determine its suitability for abrasive making. Sand at the four locations were subjected to physical and geochemical investigation. Generally, the sand was physically characterized by bright colours of white, brown and yellow. Some samples at some locations contained dark specks of organic matter. From the distribution, the sand is generally of medium grade size as shown by the Scanning Electron Microscopy (SEM). Geochemically by X-ray fluorescence (XRF) analysis, the oxide contents are: SiO2 (91.73%), CaO (0.045%), Al2O3 (4.24%), Fe2O3 (1.36%), TiO2 (0.21%), K2O (0.86%). The silica content (91.73%) of the sand is well above the industrial specification of 80% for sanitary ware making and suitable for the silica brick industry, for road dressing mixed with special asphalt. The physical and geochemical property results indicate that the sand is a good material for direct use in abrasive (sand paper and sand blasting).making, glass making and in the building and construction industries.