Dolerite occurs as blocks within serpentinite in the Kurosegawa Belt, located between the Northern and Southern Chichibu belts on Shima Peninsula, Mie Prefecture, Southwest Japan. On the peninsula, this dolerite is considered as a significant component of the “Kurosegawa Paleozoic Rocks” that define the Kurosegawa Belt. However, dolerite itself is not necessarily the component because it also appears, to a minor extent, in Jurassic accretionary complexes distributed across the Northern and Southern Chichibu belts, with a previous work having associated the dolerite with the Jurassic accretionary complexes of the Chichibu Belt on the basis of geochemistry and structural relationships.

Whole-rock geochemical analyses were conducted on dolerite within the serpentinite in the Shima Peninsula to determine its origin. The dolerite has a geochemical signature consistent with island-arc tholeiite, according to geochemical discrimination diagrams and trace-element spider-diagrams normalized to N-MORB and chondrite. This feature suggests that the dolerite is not an oceanic component within the Jurassic accretionary complexes. On the basis of the geochemistry of the mafic Kurosegawa Paleozoic Rocks in other areas, the dolerite within the serpentinite on the Shima Peninsula is inferred to be correlative with one of the Kurosegawa Paleozoic Rocks. The dolerite might also be associated with the Mitaki Igneous Rocks in the Kurosegawa Belt in Shikoku, Southwest Japan.

The Omika Debris Avalanche Deposit is exposed along the construction site of the Shin-Tomei Highway east of Mt. Fuji. This deposit is 9.3×10⁶ m³ in volume, and consists of slumped S-5 to S-22 scoria fall deposits (Fuji volcanic products) on the steep slope of Mt. Obora. This avalanche occurred between AD 848 and the middle of the 10th century, as inferred from the stratigraphy of the underlying Kozu-Tenjosan tephra and a new ¹⁴C age for the overlying soil. The AD 887 Nin'na earthquake, which was a great subduction earthquake along the Nankai Trough, took place during this period and presumably triggered the Omika Debris Avalanche.

The Sennan Rhyolites, located in the southern margin of the Late Cretaceous volcanic area of the Inner Zone of southwest Japan, are distributed in a small area along the Median Tectonic Line. They are intruded by Cretaceous granitic rocks and unconformably overlain by the Upper Cretaceous Izumi Group. We present the results of laser-ablation-inductively coupled plasma-mass spectrometry zircon U-Pb dating and fission-track (FT) dating of rhyolitic welded tuff from the Sennan Rhyolites on Awaji Island. The analyses yielded a weighted mean ²³⁸U-²⁰⁶Pb age of 94.0±1.1 Ma (2σ) and a FT age of 72.3±2.6 Ma (1σ), respectively. The U-Pb age, which is consistent with existing geochronological data and observed intrusive relationships between the Sennan Rhyolites and granitic rocks, constrains the eruption age of the Sennan Rhyolites. The FT age is significantly younger than the U-Pb age and indicates thermal resetting by granitic rocks.

Glaciological studies have been conducted on snow patches in Japan since 1910th, including the recent identification of active glaciers in the Hida Mountains. This identification was presented at an open symposium organized by the Data Center for Glacier Research of the Glaciological Society of Japan, which recognized that the snow patches have a considerable mass of ice that shows evidence of downward flow along a valley. International cryosphere-related organizations, however, have defined the glacier as a “stagnant or flowing ice mass”, and the international classification of glaciers as published by The International Commission of Snow and Ice (ICSI) requires the criterion of flow for only certain classes of glaciers, such as the valley glacier etc. The presence of ice flow is not considered necessary to define mountain glaciers and glacierets. On the basis of a pilot study in the Himalayan region as used by the ICSI, several snow patches with ice masses in Japan can be considered as a type of glacier. However, the classification is unclear in terms of criteria based on flow, size, and thickness of an ice mass, as well as in terms of distinctions between valley glaciers, mountain glaciers, glacierets, and snow patches, which should be re-examined and clarified to create a better definition and classification of snow and ice masses on Earth.

We report petrographic characteristics and whole-rock chemical compositions of the Stage 3 (after 16 ka) eruption products of Kusatsu-Shirane Volcano, central Japan. The Stage 3 eruption products analyzed in this study are from the Shirane Pyroclastic Cone Group (SPCG), the Ainomine Pyroclastic Cone, and the Yumi-ike Maar, which are all located in the northern summit area of Kusatsu-Shirane Volcano. All lavas and juvenile pyroclasts of the Stage 3 eruption products contain phenocrysts of plagioclase, orthopyroxene, clinopyroxene, and opaque minerals. In addition to these minerals, some rocks contain rare olivine, quartz, and biotite phenocrysts. The lavas that were erupted during the early activity of the SPCG (the Hebei-ike, Kagusa, and Shirane-higashi lavas) have wide variations in SiO₂ content from andesitic to dacitic and in some outcrops exhibit a heterogeneous mingled appearance. In contrast, the lavas and pyroclasts that were erupted during the later stage of the SPCG (Shirane Pyroclastic Deposits and the Mizugama Lava Dome), as well as the Ainomine and the Yumi-ike Pyroclastic Deposits, are homogeneous in appearance and have andesitic compositions. Irrespective of the relative eruption ages, the analyzed Stage 3 eruption products are all associated with the calc-alkaline and medium-K series.