後氷期のサンゴ礁への炭酸カルシウム堆積速度

抄録

Calcium carbonate deposition in the ocean results in a release of CO₂ to the atmosphere. Based on this process, a "coral reef hypothesis" was proposed to explain postglacial CO₂ increase as a result of reef growth. The model assumed that if twice the mass of atmospheric carbon (2 ACM) were deposited into coral reefs between 15,000 and 10,000 years B. P., the accompanying release of CO₂ would account for 40 ppm increase of the atmospheric CO₂. In this paper, calcium carbonate deposition rates into postglacial reefs with a time scale of 1000 years is calculated based on shallow core researches to test the hypothesis. The total reef mass is estimated to be 2 ACM. Calcium carbonate deposition rates of postglacial reefs attained their maximum between 5000 and 6000 years B. P. with a rate of 0.45 ACM for 1000 years. This major deposition phase does not match the period of observed CO₂ increase in the atmosphere. This discrepancy is not in agreement with the "coral reef hypothesis" .