seminar slide on Mineral formations.pptx

Mineral Formation

1. OUTLINE 1. Introduction 2. Divergent Boundaries and Mineral Formation 3. Convergent Boundaries and Mineral Formation 4. Transform Boundaries and Mineral Formation 5. Case Study 1 6. Case Study 2 7. Conclusion

2. INTRODUCTION Tectonic activities shape the Earth's surface, leading to the formation of geological structures like mountain ranges, ocean basins, and volcanic arcs. Metallic ores like copper, gold, iron, and zinc form through geological processes that are often tied to tectonic activities such as plate subduction, rifting, and continental collision (Kesler & Ohmoto 2006). Figure 1:Tectonic Settings of Metal Deposits. (Adapted from Skinner and Porter, 1987

3. DIVERGENT BOUNDARIES AND MINERAL FORMATION At divergent boundaries, tectonic plates separate, allowing magma to rise and form new oceanic crust. Cooling magma forms basalt, while hydrothermal vents create seafloor massive sulfide (SMS) deposits (Smith, 2020). Figure 2: The general processes that take place at a divergent boundary. The area within the dashed white rectangle is shown in Figure 3 (https://opentextbc.ca/geology)

4. DIVERGENT BOUNDARIES AND MINERAL FORMATION Figure 3: Depiction of the processes and materials formed at a divergent boundary [SE after Keary and Vine, 1996, Global Tectonics (2ed), Blackwell Science Ltd., Oxford]

5. CONVERGENT BOUNDARIES AND MINERAL FORMATION Convergent boundaries, where tectonic plates collide, play a key role in forming metallic ore deposits. These deposits are also associated with other valuable minerals like gold and molybdenum (Jones & Brown, 2019). Figure 4 : Configuration and processes of an ocean-ocean convergent boundary (https://opentextbc.ca/geology)

6. CONVERGENT BOUNDARIES AND MINERAL FORMATION Figure 5: Configuration and processes of an ocean-continent convergent boundary (https://opentextbc.ca/geology) Figure 6 : Configuration and processes of a continent-continent convergent boundary (https://opentextbc.ca/geology)

7. TRANSFORM BOUNDARIES AND MINERAL FORMATION Though transform boundaries mainly involve lateral plate movement and seismic activity, they can also impact mineral formation. For instance, transform fault zones can concentrate gold and silver in veins through mineral-rich fluid circulation (Smith, 2020). Figure 7 : The Alpine Fault is a transform boundary. The Pacific and Australian plates are trying to slide past each other (https://www.sciencelearn.org.nz/)

8. Case Study 1: The Formation of Porphyry Copper Deposits in the Andes The Andes Mountains is a key convergent boundary where the Nazca Plate subducts beneath the South American Plate (Sillitoe, 2010). Andean porphyry copper deposits form from subduction magmatism, with metals deposited near fault zones. Figure 8: The San Andreas Fault extends from the north end of the East Pacific Rise in the Gulf of California to the southern end of the Juan de Fuca Ridge. All of the red lines on this map are transform faults (https://opentextbc.ca/geology)

9. Case Study 2: Volcanogenic Massive Sulfide (VMS) Deposits at Mid-Ocean Ridges Volcanogenic massive sulfide (VMS) deposits form at mid-ocean ridges, like the Mid-Atlantic Ridge, through hydrothermal proesses that deposit copper, zinc, lead, gold, and silver (Franklin et al., 2005). Tectonic spreading creates fractures allowing seawater to heat and deposit metals, forming massive sulfide mounds (Rona, 1985). Figure 9 : A cross-section of a typical volcanogenic massive sulfide (VMS) ore deposit as seen in the sedimentary record (https://opentextbc.ca/geology)

10. C ONCLUSION T ectonic activities play a crucial role in the formation of metallic ores. Future research should focus on the exact role of magmatic versus hydrothermal processes to refine existing models and improve predictive capabilities.

11. References Jones, L., & Brown, T. (2019). Orogeny and Ore Genesis. Cambridge University Press, 105, 669 – 688 Franklin, J. M., Gibson, H. L., Jonasson , I. R., & Galley, A. G. (2005). Volcanogenic Massive Sulfide Deposits. In Economic Geology 100th Anniversary Volume (pp. 523-560). Sillitoe, R. H. (2010). Porphyry Copper Systems. Economic Geology, 105(1), 3-41. Smith, D. (2020). Mid-Ocean Ridges and Sea Floor Spreading. The Australian Institute of Mining and Metallurgy, 15 – 21. Rona, P. A. (1985). Hydrothermal Mineralization at Slow-Spreading Centers: Red Sea, Atlantic, and Indian Ocean. Economic Geology, 80(2), 413-426. Kesler, S. E. & Ohmoto , H. (eds) (2006). Evolution of Early Earth’s Atmosphere, Hydrosphere and Biosphere – Constraints from Ore Deposits. Geological Society of America, Boulder, CO, Memoirs, 198.