Kinuyo Kanamaru

Depositional evidence for the Kamikaze typhoons and links to changes in typhoon climatology

In the late 13 th century, Kublai Khan, ruler of the Mongol Empire, launched one of the world’s largest armadas of its time in an attempt to conquer Japan. Early narratives described the decimation and dispersal of these fleets by the “Kamikaze” of 1274 CE and 1281 CE, a pair of intense typhoons “divinely” sent to protect Japan from invasion. These historical accounts are prone to exaggeration, and significant questions remain regarding the occurrence and true intensity of these legendary typhoons. To provide independent insight, we present a new 2000 yr sedimentary reconstruction of extreme coastal flooding from a coastal lake near the location of the Mongol invasions. Two marine-sourced flood deposits date to the Kamikaze typhoons and are the events of record in the reconstruction. The complete reconstruction indicates periods of greater flood activity relative to modern beginning ca. 250 CE and extending past the timing of the Kamikaze events to 1600 CE. Comparisons with additional reconstructions are consistent with greater regional typhoon activity during the Mongol invasions due to the preferential steering of storms toward Japan, and driven by greater El Nino activity relative to modern. Results are consistent with the paired Kamikaze typhoons being of significant intensity, and support accounts of them playing an important role in preventing the conquering of Japan by Mongol fleets. The Kamikaze typhoons may therefore serve as a prominent example for how past increases in severe weather associated with changing climate have had significant geopolitical impacts.

New insight into Saanich Inlet varved sediments (British Columbia, Canada) from micro-scale analysis of sedimentary facies and micro-XRF core scanning analyses

The late Pleistocene and Holocene laminated marine sediments deposited in Saanich Inlet, British Columbia, contain a well-known annually resolved record of environmental change. In this paper, these sediments were analyzed for the first time with an Itrax micro-X-ray fluorescence core scanner with a resolution of 100 μm. These analyses were complemented by image analysis of backscattered scanning electron images, coupled with energy dispersive spectrometry analysis using a scanning electron microscope. Using this new information, nine sedimentary facies were identified based on distinct geochemical, sedimentological and morphological characteristics at both the macro and the microscopic scale: Facies 1: massive deposit during Termination 1 (T1), Facies 2: T1 varved sediment, Facies 3: early Holocene varved sediment, Facies 4: volcanic ash-rich sediment, Facies 5: mid-Holocene varved sediment, Facies 6: disturbed sediment, Facies 7: massive sediment, Facies 8: clay-rich layer, Facies 9: fecal pellet-rich sediment.We determined how these analyses reinforced or refined previous interpretations about the sedimentary processes responsible for their deposition, their sedimentary environments and/or their provenance with seasonal to sub-seasonal resolution. Each lithofacies has distinctive chemical and sedimentological signatures, which can be used to establish sediment provenance with seasonal to sub-seasonal resolution, and to help understand paleoclimatic variations.

Standardization and Calibration of X-Radiographs Acquired with the ITRAX Core Scanner

A calibration procedure that uses a radiographic reference sample (RRS) to compensate for instrumental, time- and sample-related variations encountered with Itrax X-radiographs is introduced. This RRS is always included whenever a core section is run on the Itrax and it allows radiographs to be standardized. This allows different cores to be compared ultimately leading to increased efficiency, cost saving and scientific value. A standardization protocol is presented that corrects for X-ray tube output (ageing), different acquisition settings and sediment core properties (diameter and material). This allows for the direct comparison and accurate concatenation of radiographic images from long sequences. Other Itrax laboratories using an identical RRS can also share radiographic data. The standardized X-ray attenuation profiles from the Itrax compare very well with attenuation profiles obtained by CT-scan, a technology providing attenuation values very close to density and not influenced by sample thickness.