Southern Kyushu Research Articles

Conservation of endangered ecosystem of warm-temperate evergreen broad-leaved forest (lucidophyllus forest) with local community : implementation of collaborative management in Aya Town, southern Kyushu, Japan

Conservation of endangered ecosystem of warm-temperate evergreen broad-leaved forest (lucidophyllus forest) with local community : implementation of collaborative management in Aya Town, southern Kyushu, Japan

Shipbuilding in Southern Kyushu and the Participation of the Shimazu Clan During the Warring States Period, with a Focus on Hyuga Province

Shipbuilding in Southern Kyushu and the Participation of the Shimazu Clan During the Warring States Period, with a Focus on Hyuga Province

Repeating deep tremors on the plate interface beneath Kyushu, southwest Japan

In the subduction zone south of Kyushu Island, at the western extension of the Nankai subduction zone, southwest Japan, the age of the oceanic crust increases toward the south across the subducting Kyushu-Palau ridge. While tremor activity is very high in Nankai, tectonic tremors have only recently been discovered in Kyushu. In this study, we examined tremors beneath Kyushu using an improved version of the envelope correlation method. In doing so, we distinguished tremors from normal earthquakes and background noise using the criteria of source duration and the spectrum ratio between low and high frequencies. Accurate measurement of S-P times, using cross-correlation between vertical and horizontal seismograms, constrains the tremor depth precisely. Tremor activity is low and within a small region in southern Kyushu, where thick crust of the Kyushu-Palau ridge is being subducted, at depths between 35 and 45 km (i.e., shallower than intra-slab earthquakes by about 20 km), which is consistent with the location of the plate interface within uncertainties proposed in previous studies. Establishing precise depth estimates for tectonic tremors beneath Kyushu, which results from shear slip along the plate interface, is useful in defining the plate interface within the Nankai subduction zone.

South-Vergent Imbricate Fan in the Ikenodan Formation of the Shimanto Supergroup, Southern Kyushu, Japan

The Noda area in Hokusatsu District, southwest Kyushu is underlain by Imanokoba, Ikenodan and Ogakura Formations of Cretaceous Shimanto Supergroup. The Imanokoba Formation comprises beds of sandstone and mudstone. The beds generally trend NE-SW and dip in a moderate to steep angles to east or west. The Ikenodan Formation comprises beds of sandstone, mudstone, siliceous mudstone and chert and basaltic lavas. The beds generally strike between NE and NW, and dip toward west in moderate to high angles with a westerly way-up. The chert and basaltic lava beds appear in a left-stepping en echelon arrangement. The contact between Imanokoba and Ikenodan Formations is in a N-S trending fault known as Noda Fault. The Ogakura Formation is composed of alternating beds of sandstone and mudstone. The beds generally strike between NE and NNE and dip toward west in moderate to high angles with westerly way-up. The contact relationship between Ikenodan and Ogakura Formations is not distinct. The westward disappearance of basaltic lava marks western limit of Ikenodan Formation. The en echelon array in Ikenodan Formation is interpreted as an imbricate fan with Noda Fault on its bottom as a decollement and is called the Ikenodan imbricate fan. The Ikenodan imbricate fan is considered to have been formed in an accretionary complex developed in a northbound subduction zone. The primary attitude of Ikenodan imbricate fan was probably south-vergent then turned over with its west side down. It was previously reported that strata of Shimanto Supergroup in Hokusatsu area form a regional bending structure called the Hokustasu Bend. The Noda area is situated in a hinge zone of Hokusatsu Bend, although formations in Noda area have not been involved in bending structure. The Ikenodan Formation and Noda Fault presumably extend to north without bending, otherwise bending structure occurs anywhere outside Noda area. In either case, Hokusatsu Bend is not present as interpreted in previous studies.

Effect of Digested Effluent of Manure on Yield, Forage Quality and Nitrogen Recovery Rate of Maize-Italian Ryegrass Cropping System in Southern Kyushu

Effect of Digested Effluent of Manure on Yield, Forage Quality and Nitrogen Recovery Rate of Maize-Italian Ryegrass Cropping System in Southern Kyushu

Stable Isotope and Geochemical Observations in the Kago Low-sulfidation Au/Ag Deposit, Southern Kyushu, Japan

The Kago low-sulfidation Au/Ag deposit was an extensively excavated mine, primarily in the Edo-period (1684), reaching as far as 1943. Au grades ranged from 4.1-13.3g/t, while Ag ranges from 2.6-6.6g/t. The higher grades of gold made this deposit more favourable to mine, in comparison to other operating mines such as Serigano towards the north. The deposit is located approximately 5km from both the Kasuga and Iwato high-sulfidation deposits located towards the south. In this study, surficial quartz veins were measured for 18O in quartz and 34S in pyrite hosted in the veins. Where available, fluid inclusion microthermometry was carried out to establish the likely temperature of the mineralising fluids. Fluid 18O compositions were estimated using microthermometry results. Host rocks surrounding the veins were analysed for their alteration mineralogy. Within the Central Vein Group (CVT), veins typically exhibit low temperature argillic alteration grading out into a regional propylitic zone.

Variation in Growth Attributes, Dry Matter Yield and Quality Among 6 Genotypes of Napier Grass used for Biomass in Year of Establishment in Southern Kyushu, Japan

Variation in Growth Attributes, Dry Matter Yield and Quality Among 6 Genotypes of Napier Grass used for Biomass in Year of Establishment in Southern Kyushu, Japan

Examining the factors influencing leaf disease intensity of Kalopanax septemlobus (Thunb. ex Murray) Koidzumi (Araliaceae) over multiple spatial scales: from the individual, forest stand, to the regions in the Japanese Archipelago

We investigated leaf disease intensity of Kalopanax septemlobus (prickly castor oil tree) caused by the parasitic fungus Mycosphaerella acanthopanacis, in thirty natural host populations in the Japanese Archipelago. The disease intensity observed for individual trees were analyzed using a generalized additive model as a function of tree size, tree density, climatic terms and spatial trend surface. Individual tree size and conspecific tree density were shown to have significant negative and positive effects on disease intensity, respectively. The findings suggest that the probability of disease infection is partly determined by dispersal of infection agents (ascospores) from the fallen leaves on the ground, which can be enhanced by aggregation of host trees in a forest stand. Regional-scale spatial bias was also present in disease intensity; the populations in northern Japan and southern Kyushu were more severely infected by the fungus than those in southwestern Honshu and Shikoku. Regional variation of disease intensity was explained by both climatic factors and a trend surface term, with a latitudinal cline detected, which increases towards the north. Further research should be conducted in order to understand all of the factors generating the latitudinal cline detected in this study.

Description of a new species of the hippolytid shrimp genus Eualus Thallwitz, 1892 from Japan, and clarification of the status of E. kikuchii Miyake & Hayashi, 1967 (Crustacea: Decapoda: Caridea)

This study reports on two species of the hippolytid shrimp genus Eualus Thallwitz, 1892 from Japan. The first, Eualusctenomerus n. sp., is described on the basis of six specimens from off southern Kyushu. The new species appears closestto E. cteniferus (Barnard, 1950) from South Africa, E. drachi Noël, 1978 from the Mediterranean, E. lebourae Holthuis,1951 from the eastern Atlantic, and E. pectiniformis Hanamura, 2008 from southeastern Australia. The second is referredto E. kikuchii Miyake & Hayashi, 1967, which has been considered to be synonymous with E. bulychevae Kobjakova,1955, described from the South Kuril Islands, Far East Russia. Eualus kikuchii is redescribed as a valid species on thebasis of the holotype and additional specimens from various Japanese localities. Both species occurred in the whale-fall ecosystems located off Cape Nomamisaki, Kyushu, Kagoshima Prefecture.

The role of tephras in developing a high-resolution chronostratigraphy for palaeoenvironmental reconst-ruction and archaeology in southern Kyushu, Japan, since 30,000 years ago

The role of tephras in developing a high-resolution chronostratigraphy for palaeoenvironmental reconst-ruction and archaeology in southern Kyushu, Japan, since 30,000 years ago

P92 桜島火山のマグマの地球化学及び記載岩石学的研究(ポスターセッション)

P92 桜島火山のマグマの地球化学及び記載岩石学的研究(ポスターセッション)

Global cooling in marine climates and local tectonic events in Southwest Japan at the Plio–Pleistocene boundary

This study reconstructs the temporal changes in water temperature and depth on the Pacific coast of Southwest Japan from the latest Pliocene to the earliest Pleistocene (ca. 2.6Ma) on the basis of the modern analog technique (MAT) of fossil ostracodes and factor analysis of fossil planktonic foraminifera from the Takanabe Formation. Around the Plio–Pleistocene boundary, the MAT results reveal that the mean annual, warmest month, and coldest month temperatures of bottom water were estimated at ca. 6–17, 6–17, and 6–16°C, respectively. The bottom water temperature before 2.6Ma was similar to modern temperatures of the study site. Since then, the temperature dropped several degrees. Moreover, the result of the analysis of fossil planktonic foraminifera suggests that the study site clearly changed from a marine climate under the influence of the axial part of the Kuroshio Current to that of transitional water at around 2.6Ma. Thus, the results of the microfossil analysis reveal for the first time that a global cooling event at the Plio–Pleistocene boundary influenced the Pacific coast of SW Japan. The change in water depth at ca 2.6Ma in the study site was estimated to have been extremely large in comparison with the global sea-level fluctuations during the late Pliocene, suggesting that the tectonic movement related to the rotation of the southern Kyushu Island, Southwest Japan, started at ca. 2.6Ma and that subsidence occurred in the study area.

Upper Triassic (Carnian) reef biota from the Sambosan Accretionary Complex, Kyushu, Japan

Calcified sponges, algae, and reef problematica are abundant yet poorly known from the Triassic of Japan. They are abundant in shallow-water carbonate, redeposited blocks of the Sambosan Accretionary Complex, Konose Group, and southern Kyushu. Based on study of thin-sections from reef limestone exposed along the Kuma River, some important organisms and reef microfacies are described, which seem typical of Upper Triassic reef complexes. The most abundant reef organisms are hypercalcified sponges, including sphinctozoans, inozoans and chaetetids, followed by cyanophycean algae (including “Tubiphytes”-like organisms), and solenoporacean red algae. Loose sponge spicules in one thin-section also indicate the occurrence of rare hexactinellid sponges. Chambered demosponges described from the Konose carbonate rocks include Solenolmia manon manon (Munster), Colospongia sp., Jablonskyia andrusovi (Jablonský), several unidentified chambered sponges as well as the inozoid Permocorynella sp. 1 and Permocorynella sp. 2. Also present are chaetetid sponges and solenoporacean red algae belonging to Parachaetetes cassianus (Flugel) and Parachaetetes? sp. or Solenopora? sp. Especially abundant in thin-sections are cyanophyceans and “Tubiphytes”-like organisms. Among the organisms is Cladogirvanella Ott and Hedstroemia sp. The composition of the biota and presence of typical problematic organisms increases our knowledge of shallow-water Upper Triassic carbonate rocks in a remote setting in western Panthalassa. The composition of the biota indicates a mostly Carnian age. Most comparable organisms are known from both the northeastern and southern Tethys.

Rifting of Kyushu, Japan, based on the fault-controlled concurrent eruption of oceanic island basalt-type and island arc-type lavas

The tectonic environment of Kyushu, Japan is affected both by the subduction of the Philippine Sea plate and by the extensional tectonics related to rifting of Okinawa Trough at the eastern margin of the Eurasia Plate. We found that the Sendai fault zone acts as a channel for concurrent eruption of oceanic island basalt (OIB)-type and island arc (IA)-type basaltic rocks, propagating west to east in the Sendai region of southern Kyushu. The location of the Sendai fault zone is likely to correspond to the left-lateral shear zone in southern Kyushu as inferred by GPS Earth Observation Network. A similar magmatic association is present in the Beppu–Shimabara (BS) graben system in central Kyushu. The associate magmas of OIB-type rocks in Kyushu can be classified into typical, EM II-like and their intermediate OIB-type magmas in addition to MORB-like OIB-type magma in 87Sr/86Sr–Nb/Y systematics. Typical OIB-type and intermediate OIB-type magmas are erupted within the Sendai fault zone and BS graben system, respectively. The former is characterized by highest Nb/Y but low 87Sr/86Sr similar to MORB-like OIB-type magma erupted in northern Kyushu and the latter has intermediate Nb/Y and 87Sr/86Sr between typical and EM II-like OIB-type magmas. Almost all the IA-type rocks within the Sendai fault zone are generated from parental IA-type magma in Kyushu and characterized by weak crustal assimilation, having the lowest 87Sr/86Sr similar to typical OIB-type magma but the highest 143Nd/144Nd of arc magmas in Kyushu. The ages of both types of basaltic rocks within the Sendai fault zone range from 1.6 to <0.01 Ma clearly younger than those of andesitic rocks on northern and southern outsides of the fault zone and become younger from west to east. Initial formation of the fault zone has been induced by the counterclockwise rotation of southern Kyushu during the last 2 Ma as well as the BS graben system. Kyushu has continued to be split into three parts by the Sendai fault zone and BS graben during the Quaternary; northern, central, and southern zones. Their initial formation ages are likely to be linked to the initial rifting age of the middle Okinawa Trough back-arc basin.

The Pliocene/Pleistocene boundary of the upper Takanabe Formation of the Miyazaki Group, southern Kyushu, Southwest Japan

The Pliocene/Pleistocene boundary of the upper Takanabe Formation of the Miyazaki Group, southern Kyushu, Southwest Japan

宮崎層群上部の石灰質微化石に基づく，鮮新世／更新世境界付近の海洋環境変遷

九州宮崎地域に分布する宮崎層群高鍋層上部は，鮮新世／更新世境界を含むことから，後期鮮新世から前期更新世の北西太平洋の海洋環境変遷を明らかにするのに適した地層である．同時代の黒潮変動を明らかにするために，宮崎県高鍋町永谷川沿いに露出する，高鍋層最上部から産出する石灰質ナンノ化石と浮遊性有孔虫化石群集を解析した．特に，古環境代替指標として用いた石灰質ナンノ化石のReticulofenestra属，Coccolithus pelagicusおよび浮遊性有孔虫化石のGlobigerinoides ruber, Globigerinoides quadrilobatus, Globigerinoides sacculifer, Neogloboquadrina incomptaが認められるほかに，石灰質ナンノ化石のDiscoaster属が特徴的に産出する．これらの種から，鮮新世末まで黒潮の影響下にあり海洋が成層化する環境から，漸移的な移行期を経て，更新世の冷水塊などによる湧昇流が卓越する海域へと変化したことを明らかにした．

九州南部のスギ人工林下層における絶滅危惧種ハナガガシの出現傾向

九州南部のスギ人工林下層における絶滅危惧種ハナガガシの出現傾向

九州東岸および北部におけるフタテンチビヨコバイの分布状況

Maize orange leafhopper Cicadulina bipunctata is distributed widely in tropical and subtropical regions of the Old World and feeds on various Poaceae. This species induces maize wallaby ear symptom, which is characterized by stunted growth and swelling of leaf veins. In Japan, damage by the leafhopper to young seedlings of the second forage maize crop was reported from Kumamoto Prefecture in the late 1980s. Because C. bipunctata is a potential pest of various cereal crops and the damage might become more severe due to global warming, we investigated the distribution of C. bipunctata in northern Kyushu and eastern parts of central Kyushu where an intensive survey has not yet been conducted. As a result, we newly collected the leafhopper from Oita Prefecture and clarified its wide distribution in eastern parts of central Kyushu. The leafhopper was not found in northern Kyushu including northern parts of Oita and Fukuoka Prefectures. This result indicates that the leafhopper is broadly distributed in lowland areas of central and southern Kyushu. Attention should be paid to a potential risk of damage by this leafhopper to various cereal crops in these areas.

B2-15 マグマ化学組成からみた60ka以降の桜島火山・姶良カルデラ地域におけるマグマ供給系の時間変化(マグマ供給系,口頭発表)

B2-15 マグマ化学組成からみた60ka以降の桜島火山・姶良カルデラ地域におけるマグマ供給系の時間変化(マグマ供給系,口頭発表)

Changes in nitrogen transformation in forest soil representing the climate gradient of the Japanese archipelago

Net nitrogen transformation was investigated under different climate conditions by soil transplantation and in situ incubation of forest surface soils using the resin-core method. Selected conditions were considered to reflect those of the natural climate gradient in the Japanese archipelago. Study sites were established in natural forests in northern Hokkaido (Uryu), northern Kanto (Kusaki), central Kinki (Kamigamo), and southern Kyushu (Takakuma), representing the northernmost to the southernmost island regions of Japan. Field experiments comparing soils incubated at “native” and “transplanted” sites were conducted from June 2008 to May 2009. Net production, accumulation, and leaching of soil ammonium (NH4+) and nitrate (NO3−) were measured at each of the sites during the growing season (June–October), the dormant season (November–May), and throughout the year. Net nitrate production was highest in Kusaki soil, especially during the growing season, whereas net ammonium production was highest in Uryu soil, the coldest site, especially during the dormant season. Net nitrate production increased significantly in soils transplanted to a warmer climate during the growing season. However, net ammonium production increased in soils transplanted to colder climates during the dormant season. These findings indicate that, with the exception of the infertile soil samples from Kamigamo, the range of natural climates in Japan has a significant effect on nitrogen availability in surface soil. In addition, the original characteristics of the nitrogen cycle of the surface soil from each native site were retained, even when marked changes in soil temperature (approximately 8°C) occurred after transplantation.