Lesson 1 - Assignment Flashcards
(5 cards)
How do intracratonic settings influence mineral deposit formation?
Intracratonic settings, which are geologically stable regions, foster the formation of mineral deposits through long-term sedimentary, magmatic, and erosional processes. Banded iron formations (BIF) and manganese deposits develop in ancient sedimentary basins with oxygen-poor waters. Placer deposits, such as gold and heavy minerals, accumulate due to weathering and sedimentation along coastlines.
Large igneous intrusions, like the Bushveld Complex, produce nickel, copper, and platinum group elements (Ni-Cu-PGE). Additionally, kimberlite and lamproite pipes transport diamonds from deep mantle sources, while erosion redistributes and exposes these deposits over time.
What are the key geological processes at divergent margins that lead to mineral deposit formation?
Divergent margins, where tectonic plates separate, are characterized by mantle upwelling, partial melting, and hydrothermal circulation. These processes generate key mineral deposits, including Iron Oxide-Copper-Gold (IOCG), volcanogenic massive sulfide (VMS), and nickel-copper sulfides.
Magmatic differentiation and the interaction of mantle-derived magmas with crustal rocks contribute to the formation of these ore bodies. Hydrothermal vents at mid-ocean ridges facilitate metal precipitation, particularly copper, zinc, and lead-rich VMS deposits. Additionally, basin-wide exhalative processes lead to sediment-hosted deposits like SEDEX and Kupferschiefer.
How does lithospheric and mantle dynamics influence mineral deposit formation?
Lithospheric and mantle processes play a fundamental role in mineralization. Mantle plumes, rising from deep within the Earth, drive partial melting and magma generation, forming deposits like IOCG and Ni-Cu-PGE. The subcontinental lithospheric mantle influences magmatism and metasomatism, enriching rocks with light lithophile elements and titanium.
Asthenospheric upwelling, caused by lithospheric stretching, enhances magma production, which in turn contributes to the formation of deposits at both intracratonic and divergent settings. These interactions illustrate the deep-rooted connection between tectonics and mineral resource distribution.
What are the main types of mineral deposits associated with convergent plate boundaries?
Convergent boundaries, where tectonic plates collide, create high-temperature and high-pressure environments that foster the formation of porphyry, epithermal, and volcanogenic massive sulfide (VMS) deposits. Porphyry deposits, rich in copper, gold, and molybdenum, form due to magmatic intrusions and hydrothermal fluid circulation. Epithermal deposits, enriched in gold and silver, result from metal-bearing fluids migrating through fractures. Some convergent settings also host VMS deposits, where hydrothermal vents on the seafloor expel metal-rich fluids, leading to the accumulation of copper, lead, and zinc sulfides.
How do mineral deposits form at divergent boundaries, continental rifts, and passive margins?
Divergent Boundaries: Metal-rich hydrothermal fluids circulate at mid-ocean ridges, precipitating copper, zinc, and lead in VMS deposits.
Continental Rift Zones: As continents stretch apart, rift basins form, hosting sedimentary copper and evaporite deposits. These environments concentrate metals from sedimentary layers and precipitate salts in arid conditions.
Passive Margins: While less active tectonically, these regions accumulate sediment-hosted mineral deposits, such as phosphorites, from organic-rich environments.
