16:30 〜 16:45
[AHW18-20] Reconstruction of Holocene provenance and delivery mass of change in Beppu Bay in using mineral composition
キーワード：別府湾、古環境、海洋堆積物、X線回折、PARAFAC解析 (多変量解析的手法)、鉱物組成
Mineral composition of terrestrial debris reflects environment such as climate, validation, weathering, and delivering. Thus, analyzing mineral composition of debris in past deposition can reconstruct paleo-environment in watershed. Proxies relate paleo-reconstruction is valid, and paleo-reconstruction using composition of terrestrial debris in humid climate and in river system including various geology in watershed could be effective. Therefore, we researched Beppu Bay, Oita river, and Ono river in northeast Oita. Riverine water sampled in December 2010 and July 2016, and Beppu Bay core sampled in previous study are analyzed. BP09-03 is recognized as continuous record in past 3000 years, so era change of provenance and transport of terrestrial debris in Beppu Bay watershed in the Holocene can be estimated.
We analyzed concentration of suspended sediment using riverine water and riverine mineral composition using PARAFAC to understand. Also, mineral composition of Beppu Bay core and riverine debris of Oita River and Ono River are analyzed by X-ray diffraction.
Concentration of suspend sediment on July 2016 was more 40 times than on December 2010, and Compared with past data of concentration of suspended sediment at Water Information System of MLIT, there were far higher concentration in our study’s sample, because it was heavy rain when we gained samples and data between heavy rain cannot have been gained by MLIT routine observation.
We performed parallel factor analysis (PARAFAC) analyzation to present XRD profiles of Beppu Bay core as superimpose of clastic end-member. The result is that 7 end-member mixing model were most suitable. XRD profiles of end-member are confirmed as three hemipelagic, two events, and the other (biogenic, sea salt). Considered change of each end-member across the ages, it was identified that biogenic and sea salt were almost constant, and that of hemipelagic and event presented characteristic change.
Compared with other proxies, substantiation of result showed this research and relevancy to other paleo-environmental were indicated as the one of methods of paleo-environmental reconstruction.
We analyzed concentration of suspended sediment using riverine water and riverine mineral composition using PARAFAC to understand. Also, mineral composition of Beppu Bay core and riverine debris of Oita River and Ono River are analyzed by X-ray diffraction.
Concentration of suspend sediment on July 2016 was more 40 times than on December 2010, and Compared with past data of concentration of suspended sediment at Water Information System of MLIT, there were far higher concentration in our study’s sample, because it was heavy rain when we gained samples and data between heavy rain cannot have been gained by MLIT routine observation.
We performed parallel factor analysis (PARAFAC) analyzation to present XRD profiles of Beppu Bay core as superimpose of clastic end-member. The result is that 7 end-member mixing model were most suitable. XRD profiles of end-member are confirmed as three hemipelagic, two events, and the other (biogenic, sea salt). Considered change of each end-member across the ages, it was identified that biogenic and sea salt were almost constant, and that of hemipelagic and event presented characteristic change.
Compared with other proxies, substantiation of result showed this research and relevancy to other paleo-environmental were indicated as the one of methods of paleo-environmental reconstruction.