Climate and Slopes

Climate and carbonates

Generation of carbonates in the marine setting is controlled by temperature of the seawater, amount of carbon dioxide in the water. Sea level (as controlled by climate, not just tectonics) also plays a role in the creation of carbonates. When sea level is at a highstand, the slope is apt to receive the largest amounts of sediment during these times as a result of the carbonate platform being its most productive.

carbonate sediments only precipitate from waters that are low in CO2. In order for the waters to contain small amounts of CO2, the waters must be warm (because carbon dioxide is less soluable than in colder waters). Therefore, carbonate sediments occur primarily in tropical seas where the seawater temperatures do not drop below 18ºC (64ºF). Therefore, most commonly they are deposited in shallow seas in tropical regions, generally, between 30ºN and 30ºS.

For example, during glacial times, sea level, carbon dioxide values, and seawater temperatures were all lower. Therefore, these would all play a part in changing the distribution of carbonate deposits on continental slopes during glacial times.

Notice on the map below the areas of the ocean which are greater than 18ºC (light green, yellows, oranges, and reds):



Now, notice how this temperature map corresponds to the distribution of carbonate sediments:

After (Archer, 2000)


Ancient Slopes

Tuesday, February 24, 2015
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