17:15 〜 18:30
[MIS16-P23] Os同位体分析に基づく古第三紀超温暖化イベントにおける化学風化フィードバックの考察
キーワード：Os同位体比、古第三紀、超温暖化、化学風化、地球システムフィードバック
During the early Paleogene, multiple rapid global warming events called ‘hyperthermals’ occurred in a geologically short time scale (104–105 yr) [1]. These events coincided with distinct negative carbon isotope (δ13C) excursions, which indicates that the cause of hyperthermals was massive injection of 13C-depleted greenhouse gases [2].
Chemical weathering of continental silicate rocks is known as one of the recovery processes from such warming events. Some previous studies have shown an intensification of the chemical weathering during the Paleocene-Eocene Thermal Maximum (PETM), using an osmium isotope ratio (187Os/188Os) in the ocean, which can constrain the changes in chemical weathering associated with short-term warming [3,4]. However, the marine Os isotope record during the early Eocene hyperthermals, including the PETM, has not been reported from the pelagic area of the Pacific Ocean.
In the presentation, we will report the results of 187Os/188Os measurement of deep-sea sediment samples collected from Ocean Drilling Program Site 1215 Hole A in the central North Pacific Ocean, which record multiple hyperthermal events including the PETM, Eocene Thermal Maximum (ETM) 2 and ETM3 [5]. Based on the analytical results, we will discuss the changes in the intensity of chemical weathering of continental silicate rocks during each hyperthermal event.
[1] Zachos et al. (2008) Nature 451, 279-283. [2] Lunt et al. (2011) Nature Geoscience 4, 775-778. [3] Ravizza et al. (2001) Paleoceanography 16, 155-163. [4] Dickson et al. (2015) Palaeogeography, Palaeoclimatology, Palaeoecology438, 300-307. [5] Leon-Rodriquez and Dickens (2010) Palaeogeography, Palaeoclimatology, Palaeoecology 298, 409-420.
Chemical weathering of continental silicate rocks is known as one of the recovery processes from such warming events. Some previous studies have shown an intensification of the chemical weathering during the Paleocene-Eocene Thermal Maximum (PETM), using an osmium isotope ratio (187Os/188Os) in the ocean, which can constrain the changes in chemical weathering associated with short-term warming [3,4]. However, the marine Os isotope record during the early Eocene hyperthermals, including the PETM, has not been reported from the pelagic area of the Pacific Ocean.
In the presentation, we will report the results of 187Os/188Os measurement of deep-sea sediment samples collected from Ocean Drilling Program Site 1215 Hole A in the central North Pacific Ocean, which record multiple hyperthermal events including the PETM, Eocene Thermal Maximum (ETM) 2 and ETM3 [5]. Based on the analytical results, we will discuss the changes in the intensity of chemical weathering of continental silicate rocks during each hyperthermal event.
[1] Zachos et al. (2008) Nature 451, 279-283. [2] Lunt et al. (2011) Nature Geoscience 4, 775-778. [3] Ravizza et al. (2001) Paleoceanography 16, 155-163. [4] Dickson et al. (2015) Palaeogeography, Palaeoclimatology, Palaeoecology438, 300-307. [5] Leon-Rodriquez and Dickens (2010) Palaeogeography, Palaeoclimatology, Palaeoecology 298, 409-420.