Topics on carbonate relevant topics by IODP

Abstract

Integrated Ocean Drilling Program (IODP) drilled into coral reefs, deep-water coral mounds and sediments to understand the change of climate, and biogeochemical cycle. IODP Expedition 310 around Tahiti enabled to delineate the course of last deglacial sea level rise and its impact on reef growth and geometry at this island. Amplitude of the sea-level jump around melt water pulse-1A (MWP-1A) was estimated at 12-22 m (most likely 14-18 m). Sea-surface temperature variations in 20-10 kyr indicated a temperature drop of 1.5 °C at the Younger Dryas. IODP Expedition 325 recovered Pleistocene reef materials around Great Barrier Reef. More than 1,000 radiometric dates revealed detailed sea level pictures before and after the last glacial maximum (LGM: 20,000 years ago). We successfully reported more than 5℃ lowering of SST during the LGM. IODP Expedition 307 revealed the interior of a deep-water coral mound at ~800 m deep in Northern East Atlantic. Our age model based on Sr isotope recognized two growth stages; the depositionally continuous lower reef (2.6-1.7 Ma) accumulated under the low-amplitude relative sea-level change, and the discontinuous upper reef (1.0 Ma to mid-Holocene) developed under the high-amplitude relative sea-level change. The reef initiation was temporally correlated to the global cooling at the beginning of Pleistocene, when modern circulation was established in Atlantic. IODP Expedition 320/321 recovered a series of equatorial Pacific sediments covering the past 53 million years. Cenozoic evolution of carbonate compensation depth in the equatorial Pacific was reconstructed. It tracks a long-term deepening from 3.0-3.8 km during the Eocene to 4.6 km at present, which is superimposed by large fluctuations during the middle to late Eocene, and ended with a sharp >500 m deepening during the Eocene-Oligocene transition. Those variations are closely linked to changes in global climate and carbon cycle.