17:15 〜 19:15
[MIS23-P01] Non-destructive analysis of sediment cores collected on the southwestern flank of the Shatsky Rise during Cruise KH-24-1
キーワード：シャツキー海台、海底堆積物、更新世、X線CT、MSCL
Shatsky Rise is a large igneous province (LIP) in the western North Pacific Ocean, which formed between 147 and 124 million years ago. Its summit reaches 1950 m below sea level (mbsl) whereas the depth of the deep-sea basin around Shatsky Rise is 5500–6000 mbsl [1]. Since Shatsky Rise is situated within the North Pacific subtropical gyre and on the course of the westerlies, nutrient supply around the Shatsky Rise has been attributed to surface current (i.e., Kuroshio Extension and Oyashio Current) and intensified westerlies transporting eolian dust [2–5].
Recently, the nutrient supply system around the Kuroshio area and in the oligotrophic gyre southern off the Shatsky Rise has been reevaluated, considering deep-sea turbulence and upwelling involving the interaction of bottom water current and “topographic high” [6, 7]. However, observations have not verified that such a huge topography can function as a physical barrier to supply nutrients to the surface ocean from the deeper layer. Notably, previous ocean drilling on the southwestern flank of the Shatsky Rise confirmed a sedimentary hiatus between the Pliocene and Cretaceous, implying the existence of strong bottom currents in this area [8].
Therefore, Cruise KH-24-1 aimed to reveal the relationships between depositional environments and paleoceanographic changes, including the intensification of the bottom current, on the southwestern flank of the Shatsky Rise. During Cruise KH-24-1, we conducted piston and multiple coring and CTD observations. These sediment samples are considered to cover the last 500 kyrs. In this presentation, we will introduce the preliminary results of Cruise KH-24-1, focusing on the non-destructive analysis (X-ray CT and MSCL) of the sediment cores and discussing the possibility of further research related to CTD observations.
[1] Zhang et al. (2016) Earth Planet. Sci. Lett., 441, 143–156. [2] Chiyonobu et al. (2012) Mar. Micropaleontol., 96–97, 29–37. [3] Seo et al. (2018) Palaeogeogr. Palaeoclimatol. Palaeoecol., 496, 323–331. [4] Amo and Minagawa (2003) Org. Geochem., 34, 1299–1312. [5] Maher et al. (2010) Earth Sci. Rev. 99, 61–97. [6] Ohta et al. (2020) Sci. Rep., 10, 9896. [7] Kobari et al. (2020) Biogeosciences, 17, 2441–2452. [8] Bralower et al. (2002) Proc. ODP., 198
Recently, the nutrient supply system around the Kuroshio area and in the oligotrophic gyre southern off the Shatsky Rise has been reevaluated, considering deep-sea turbulence and upwelling involving the interaction of bottom water current and “topographic high” [6, 7]. However, observations have not verified that such a huge topography can function as a physical barrier to supply nutrients to the surface ocean from the deeper layer. Notably, previous ocean drilling on the southwestern flank of the Shatsky Rise confirmed a sedimentary hiatus between the Pliocene and Cretaceous, implying the existence of strong bottom currents in this area [8].
Therefore, Cruise KH-24-1 aimed to reveal the relationships between depositional environments and paleoceanographic changes, including the intensification of the bottom current, on the southwestern flank of the Shatsky Rise. During Cruise KH-24-1, we conducted piston and multiple coring and CTD observations. These sediment samples are considered to cover the last 500 kyrs. In this presentation, we will introduce the preliminary results of Cruise KH-24-1, focusing on the non-destructive analysis (X-ray CT and MSCL) of the sediment cores and discussing the possibility of further research related to CTD observations.
[1] Zhang et al. (2016) Earth Planet. Sci. Lett., 441, 143–156. [2] Chiyonobu et al. (2012) Mar. Micropaleontol., 96–97, 29–37. [3] Seo et al. (2018) Palaeogeogr. Palaeoclimatol. Palaeoecol., 496, 323–331. [4] Amo and Minagawa (2003) Org. Geochem., 34, 1299–1312. [5] Maher et al. (2010) Earth Sci. Rev. 99, 61–97. [6] Ohta et al. (2020) Sci. Rep., 10, 9896. [7] Kobari et al. (2020) Biogeosciences, 17, 2441–2452. [8] Bralower et al. (2002) Proc. ODP., 198