Carbon Sequestration of the Middle Miocene Sunda Shelf Facilitated Global Climate Change

作者：Ma, Pengfei^*; Liu, Zhifei; Jiang, Meichen; Cheng, Han; Zhang, Lin; Cai, Dizhu

来源：Geophysical Research Letteres, 2022, 49(21): e2022GL100638.

DOI：10.1029/2022GL100638

• ORGANIC-CARBON
• SEA-LEVEL
• MONTEREY FORMATION
• NAPLES-BEACH
• SEDIMENT
• EVOLUTION
• BURIAL
• CYCLE
• PRESERVATION
• DEPOSITION

Long-term organic carbon (OC) burial on continental shelves has been widely recognized for regulating atmospheric CO2 (pCO(2)) and the global climate. However, quantitatively assessing shelf OC burial's role and process in prominent climate transitions is challenging. Using 367 drilling sites, we evaluated the impact of OC burial on the Sunda Shelf, the world's largest tropical shelf, on the middle Miocene carbon perturbation and climate change. Comparing the Miocene Climatic Optimum (MCO) and the Middle Miocene Climate Transition (MMCT) results demonstrated that OC was buried faster during the MMCT with an increment of 0.07-0.14 x 10(3) GtC/Myr. This would cause an additional 34.77-69.16 ppm pCO(2) sequestration, contributing at least one-sixth of the global pCO(2) reduction. We found OC burial regulated the long-standing Monterey carbon isotope excursion via negative and positive feedbacks during the MCO and MMCT, respectively. Expanded terrestrial carbon reservoirs and enhanced burial efficiency were key steps in the latter positive feedback. @@@ Plain Language Summary The organic carbon (OC) formed by the photosynthesis of marine and terrestrial organisms consumes atmospheric CO2 (pCO(2)). Its long-term burial in marine environments, especially on continental shelves, could influence the global carbon cycle and induce climate change. However, precisely assessing how much OC has been buried on shelves and quantifying how it affected climate change in the geological past is challenging. This is mainly due to the difficulty of obtaining complete spatial-temporal records buried deeply on shelves and the complexity of climate feedbacks involving OC burial. To fill this gap to a certain extent, we calculated the middle Miocene OC burial of the Sunda Shelf, the world's largest tropical shelf, using 367 drilling sites and evaluated its impact on the profound carbon perturbation and climate transition of this period. We found that more OC was buried during the greenhouse period, but a faster burial rate occurred after polar cooling. The accelerated OC burial on the Sunda Shelf would cause an additional 34.77-69.16 ppm pCO(2) sequestration, accounting for at least one-sixth of the global pCO(2) reduction of the middle Miocene. Efficient OC burial on the shelf was promoted by drainage system progradation and vegetation expansion arose along with sea level drop.

• 单位
  同济大学