GL101 Lecture 22: Resources
Document Summary
Mississippi valley-type (mvt) deposits: unusual hydrothermal deposits, metal bearing brines migrate towards the edge of a sedimentary basin. Sedimentary deposits and react with limestone: banded iron formations. Reducing conditions in early precambrian: ferrous iron in solution: superior-type banded iron formations alternating bands of iron oxides and chert, placer deposits i. e. deposits along west lake superior. Heavy metals and minerals are sorted in streams and beaches. Mined by planning, slicing, hydraulic monitoring i. e. gold, platinum, diamonds. Metamorphic deposits: most important deposits form by contact metamorphism. Weathering deposits: secondary enrichment: concentrate metals into economically valuable deposits, bauxite: Residual of chemical weathering, soluble elements removed by leaching, less soluble oxides and hydroxides left. Petroleum migration surface: hydrocarbon fluids are mobile, less dense than water so migration is typically upward (toward, will reach surface unless stopped by a petroleum trap, at surface volatile components will evaporate, petroleum trap types: Coal: burial and decomposition of plant material, oxygen-poor depositional environment, major global fossil fuel.
