Japan Geoscience Union Meeting 2018

Presentation information

[JJ] Evening Poster

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS10] Paleoclimatology and paleoceanography

Wed. May 23, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Yusuke Okazaki(Department of Earth and Planetary Sciences, Graduate School of Science, Kyushu University), Atsuhiko Isobe(Research Institute for Applied Mechanics, Kyushu University), Akihisa Kitamura(静岡大学理学部地球科学教室, 共同), Masaki Sano(Faculty of Human Sciences, Waseda University)

[MIS10-P13] Analyses of XRF corescanner data of sediment cores in the Gulf of Alaska

*Keiji Horikawa1, Takehiro Motou2, Masafumi MURAYAMA3, Osamu Seki4 (1.Graduate School of Engineer and Science, University of Toyama, 2.Faculty of Science, University of Toyama, 3.Kochi University, 4.Institute of Low Temperature Science, Hokkaido University)

Keywords:Gulf of Alaska, XRF corescanner, mountain glaciers, deglaciation

The drainage area of the Gulf of Alaska (GoA) has about 13 % of mountain glaciers in the world, and a half of freshwater supplied to the GoA is attributed to the Alaskan mountain glaciers. Further, the freshwater volume supplied to the GoA is the second largest in the Pacific, influencing a freshwater mass balance in the Arctic Ocean. The melting of these Alaskan mountain glaciers represents the highest rates in the world (Woodgate and Aagaard, 2005 GRL; Royer and Grosch, 2006 GRL), and the Alaskan mountain glaciers are considered to lose 60 % of the present ice mass by 2100 year due to the global warming.
We collected a sediment core (~8.5 m long) in the GoA during the KH17-3 cruise. XRF corescanner measurements (ITRAX, Cox analytical systems) were conducted for core CL14 (59º33.350’N, 144º 09.344’W,695 m water depth) to obtain high-resolution productivity records and meltwater-related river discharge records. This core covers the last 15 kyr, which shows two higher productivity intervals marked by higher Br intervals (Dimbitsky et al., 2001). These higher productivity intervals represented Bolling/Allerod and meltwater pulse-1B. Fe and Ti, proxies for detrital materials, represented two higher intervals in the early B/A period, corresponding to meltwater pulse 1A. Higher Fe and Ti intervals during meltwater pulse 1A indicate the huge loss of the Cordilleran Ice Sheet that developed in the western Canada and America during the last glacial maxium. During meltwater pulse 1A, marine productivity was not enhanced even though colloidal-Fe was significantly supplied from the meltwater of glaciers (Schroth et al., 2014).