Final answer:
Diamonds are commonly found in allu`vial deposits, which are loose, unconsolidated materials in geological deposits formed by erosion and transported by water bodies.
Step-by-step explanation:
All`uvial deposits are loose, unconsolidated materials that are formed by the erosion of rocks and transported by water bodies like rivers and streams.
Here's a explanation of how diamonds end up in allu`vial deposits:
- 1. Primary Sources: Diamonds are formed deep within the Earth's mantle under high pressure and temperature conditions. They are brought to the surface through volcanic activity in igneous rocks called kimberlite or lamproite pipes. These primary sources contain diamonds but are usually not economically viable to mine directly.
- 2. Erosion: Over time, weathering and erosion break down the primary sources, releasing diamonds into the surrounding environment. Water bodies like rivers and streams are powerful agents of erosion and play a significant role in transporting diamonds.
- 3. Transportation: As water flows downhill, it picks up sediments, including diamonds, from the eroded rocks. The water's current carries these sediments downstream, and the diamonds become concentrated along with other heavier materials.
- 4. Deposition: When the water loses energy, such as when it slows down or encounters a change in the landscape, it deposits the sediments it carries. This leads to the formation of allu`vial deposits. The deposits may accumulate in riverbeds, floodplains, or deltas, depending on the specific geological conditions.
- 5. Diamond Concentration: As the sediments settle, diamonds, being heavy and resistant to erosion, tend to concentrate in certain areas within the allu`vial deposits. This is why all`uvial deposits are often targeted for diamond mining.
Examples of allu`vial diamond deposits include the famous diamond mines along the Orange River in South Africa and the allu`vial diamond fields in the Amazon Basin.