Late Silurian halysitid corals from the Okanaro Group in Ehime Prefecture, Southwest Japan

The Triassic Taho Formation crops out in Taho, Shirokawa Town, Seiyo City, Ehime Prefecture, Southwest Japan. The formation is newly divided into the Tahogawa and Sakuragatouge members. The Tahogawa Member consists mainly of partly dolomitized light-, dark-, brownish-gray and black bedded limestones, and yields abundant Early to Middle Triassic conodonts, ammonoids, gastropods, bivalves, brachiopods and fish remains. The Sakuragatouge Member is dominated by brownish gray lenticular conglomeratic limestone and massive gray and white limestones that contain Middle to Late Triassic conodonts, gastropods, bivalves, echinoids and fish remains. In the Tahogawa Member, conodont assemblages are composed of 13 genera and 45 species, including three new species: Neospathodus arcus Maekawa sp. nov., Novispathodus shirokawai Maekawa sp. nov., and Nv. tahoensis Maekawa sp. nov. The member is divided into five conodont zones in ascending order: the Ns. dieneri Zone, the Ns. cristagalli Zone, the Nv. ex gr. waageni Zone, the Nv. pingdingshanensis Zone and the Nv. brevissimus Zone. The Nv. ex gr. waageni Zone contains three conodont subzones (the Eurygnathodus costatus Subzone, the Guangxidella bransoni Subzone and the Scythogondolella milleri Subzone), and the Nv. brevissimus Zone includes the Icriospathodus collinsoni Subzone. The conodont biostratigraphy of the member indicates a late Dienerian to early Spathian age, and correlates with that of Tethyan and Panthalassean sections. The Induan-Olenekian boundary is indicated by the first occurrence of Nv. ex gr. waageni. The Smithian-Spathian boundary is immediately below or intercalated within the Nv. pingdingshanensis Zone.

Gross morphology and internal texture of tufa deposits in Shirokawa Town, Ehime Prefecture, vary due to local environments (including flow condition, substrate topography, and associated biota) within the tufa-bearing stream. Variations in gross morphologies of the tufa deposits include 1) tufa encrusting boulders, 2) plane slope, 3) mound, 4) terraces, and 5) cascade. These types are basically related to variations in the original topography although they share similarities in a local environment of strong water flow which is an essential condition for active tufa deposition. Laminated internal texture, the most striking feature of the Shirokawa tufa, normally develops in tufas colonized by cyanobacteria inhabiting the surface. Regular lamination is most commonly developed along the narrow water passage of the lower stream where strong water flow continues throughout the year. The laminated tufas consist of repetition of dense lighter-colored laminae and porous darker-colored laminae, which correspond to the summer and winter deposits, respectively. The lighter laminae are characterized by thick calcite encrustation on upward-growing filamentous cyanobacteria. The darker laminae also mainly consist of calcite encrustation of cyanobacterial filaments, but the porosity largely remains. The annual rhythm seen in the laminated texture can be explained by seasonal variation in abiotic calcite precipitation rate (large in summer and small in winter) which increases with water temperature, Ca2+ contents, and flow strength. Because of the well-defined chronological constrains, continuous deposits of laminated tufas can be excellent material for reconstructing terrestrial climates.

Two rudist taxa, Epidiceras speciosum (Munster) and Monopleura sp. were discovered from the allochthonous Torinosu-type limestone blocks in the Oriai Formation of the Imaidani Group in the Shirokawa area, Southwest Japan. The occurrence of Epidiceras speciosum, indicating a late Kimmeridgian to early Valanginian age, is consistent to the previous age assignment based on the occurrences of middle Kimmeridgian to early Tithonian ammonites (Hybonoticeras) from the overlying Nakatsugawa Formation and the Tithonian radiolarian assemblage of the Imaidani Group. These limestone blocks were thus originally deposited in a shallow marine shelf in the late Kimmeridgian-early Tithonian, and were transported into a deeper environment of shelf slope in the early Tithonian. Monopleura sp. from the Shirokawa area possibly represents the earliest record of this genus and family. The occurrence of Late Jurassic rudists in Torinosu-type limestone suggests that rudists had already expanded globally and that a tropical-subtropical condition prevailed in the shallow marine shelf of East Asia, where the Torinosu-type limestone was deposited at that time.

Katayamalite occurs as a fine-grained accessory mineral amounting to 0.3–0.5 percent by volume in the aegirine syenite from Iwagi Islet, Ehime Prefecture, Southwest Japan. It coexists usually with albite, aegirine and pectolite. To the naked eye, katayamalite is white in color and phosphorescent to the ultraviolet rays. Striation white, luster vitreous. Hardness (Mohs) 3.5–4.0. Specific gravity 2.899 (calc), 2.91 (meas.). (001) cleavage is perfect. In thin section it is colorless with strong absorption. α=1.670, β=1.671, γ=1.677, γ−α=0.007, 2V(+)=ca. 32°.Chemical analysis shows SiO2 52.31, TiO2 10.99, Fe2O3 0.29, MnO 0.22, Li2O 3.25, CaO 28.25, Na2O 0.22, K2O 2.89, H2O 1.21, F 0.34, –O=F2 0.14, total 99.83%, corresponding ideally to (K, Na)Li3Ca7(Ti, Fe+3, Mn)2[Si6O18]2(0H, F)2 with Z=4.Katayamalite is triclinic with a0=9.721, b0=16.923, c0=19.942A, α=91.43°, β=104.15°, γ=89.94°, Space group C1. The strongest lines in X-ray powder data are 3.23 (100) (006·0-44), 3.06 (30) (2-43), 2.943 (30) (-3-14·3-11·-153), 2.898 (30) (-2-44·2-42), 2.417 (30) (008), 1.933 (40) (00.10).Katayamalite resembles baratovite (Dusmatov et al., 1975) both structurally and also chemically, but it is distinguished from the latter by the difference in crystal system and unit cell parameters. Dominance of OH over F and lacking of Zr replacing Ti are another chemical features of katayamalite.The name katayamalite is given for the mineralogist, Emeritus Professor Nobuo Katayama.

Bottom environmental changes during the past 200 years in Mishou Bay, Ehime Prefecture, South west Japan

P-264 Bottom environmental changes during the last 150 years in Mishou Bay, Ehime Prefecture, Southwest Japan

Invited] (entry) Granitic magma processes during the Cretaceous flare-ups recorded in Cretaceous plutonic rocks from Kajishima Island, Ehime Prefecture, southwest Japan.

Murakamiite (IMA2016-066), ideally LiCa 2 Si 3 O 8 (OH), is a new mineral that was recently discovered in an aegirine-augite albitite exposed on the Iwagi Islet, Ehime Prefecture, Japan. It occurs as prismatic crystals and monomineralic aggregates up to 1.7 mm long, is white to colourless with a white streak, and has a vitreous to silky lustre. It has a Mohs hardness of 4½–5 and is brittle with a splintery fracture and perfect {1 0 0} and {0 0 1} cleavage. Measured and calculated densities are D meas = 2.86(1) and D calc = 2.85(1) g·cm −3 , respectively. Murakamiite is optically biaxial (+) and non-pleochroic, with refractive indices (in white light) of α = 1.602(1), β = 1.611(1), γ = 1.643(1), and with 2 V meas = 56–59(2)° and 2 V calc = 57°. Dispersion is weak, with r > v . The optical orientation is X ^ c 10–11°, Y ^ a 10–14°, Z ^ b 0–5°. Murakamiite is triclinic, belonging to space group P 1 ¯ with the unit-cell parameters a = 7.9098(2) A, b = 7.0320(2) A, c = 6.9863(2) A, α = 90.596(2)°, β = 95.589(2)°, γ = 102.767(2)°, V = 376.98(2) A 3 ( Z = 2). The eight strongest lines in the X-ray powder diffraction pattern are [ d obs /A( I )( h k l )]: 2.897(100)(2 2 ¯ 0), 3.055(49)(0 1 2, 1 0 2, 1 1 ¯ 2 ¯ ), 3.295(41) (1 0 2 ¯ ), 3.225(33)(2 0 1), 3.845(20)(2 0 0), 2.284(19)(1 0 3 ¯ ), 2.720(15)(1 2 1 ¯ , 2 2 ¯ 1, 2 0 2 ¯ ), and 6.962(15)(0 0 1). The chemical composition is (average of sixteen analyses by LA–ICP–MS, H 2 O by TG–DTA, wt%): SiO 2 54.94, Al 2 O 3 0.01, FeO 0.38, MnO 0.80, MgO 0.04, CaO 34.14, Na 2 O 4.37, Li 2 O 2.52 and H 2 O 2.80. The empirical formula of murakamiite, based on 9 O apfu , is (Li 0.55 Na 0.46 ) Σ1.01 (Ca 1.98 Mn 0.04 Fe 0.02 ) Σ2.04 Si 2.98 O 8 (OH) 1.01 ; thus, muakamiite is a H-bearing pyroxenoid with three-periodicity of SiO 4 tetrahedra and the Li-analogue of pectolite. The species is named in honour of the late Professor Emeritus Nobuhide Murakami (1923–1994) of Yamaguchi University, Japan. Type specimens are housed in the National Museum of Nature and Science, Tsukuba, Japan, and the Geological and Mineralogical Museum of Faculty of Science, Yamaguchi University, Japan.

The effect of nineteenth century reclamation to seafloor environment in Mishou Bay, Ehime Prefecture, Southwest Japan.

Sugilite occurs as an essential mineral amounting to 3–8 percent by volume in aegirine syenite from Iwagi Islet, Ehime Prefecture. It is associated with albite, aegirine, pectolite and a Ca-K-Ti silicate (a still to be identified mineral). Sugilite is light brownish yellow, luster vitreous, streak white. Symmetry hexagonal. Cleavage 0001 weak. Hardness 6–61/2. Specific gravity 2.802 (calc.), 2.74 (meas.).Under the microscope, it is uniaxial negative with e=1.607, ω=1.610, ω−e=0.003, and colorless.Estimated chemical composition is SiO2 71.38, TiO2 0.51, A12O3 2.97, Fe2O3 12.76, FeO 0.19, Li2O 3.14, Na2O 4.37, K2O 3.76, H2O(+) 0.81, H2O(−) 0.12, total 100.01%, corresponding ideally to (K, Na)((H2O), Na)2(Fe3+, Na, Ti, Fe2+)2(Li, Al, Fe3+)3(Si12O30) with Z=2.The unit cell dimensions are a0=10.007(2), c0=14.000(2)A. Space group D26h−P6⁄mcc. X-ray powder data resemble those for sodgianite, milarite, osumilite, merrihueite, roedderite and brannockite.It is clear from the above-cited data that sugilite has milarite-type structure and resembles sodgianite and brannockite in containing lithium in tetrahedral site, but it is distinguished by a high content of ferric iron in 6-coordination.The name is given in honour of the late Professor Ken-ichi Sugi (1901-1948), who first found the occurrence of this mineral with Mr. M. Kutsuna.

Geochronological Examination and Geomorphic Evolution of River Terraces Distributed along the Hiji-kawa River in Ehime Prefecture, Southwest Japan: Based on Topographic Continuity and Weathered Degree of Gravels

愛媛県西予市の田穂層(三畳紀前期)産の板鰓類リソドゥスの歯化石

Carbon isotope stratigraphy of the Late Jurassic and earliest Cretaceous was revealed from Torinosu‐type limestone, which was deposited in a shallow‐marine setting in the western Paleo‐Pacific, in Japan. Two sections were examined; the Nakanosawa section of the late Kimmeridgian to early Tithonian age (Fukushima Prefecture, Northeast Japan), and the Furuichi section of the late Kimmeridgian to early Berriasian age (Ehime Prefecture, Southwest Japan). The age‐model was established using Sr isotope ratio and fossil occurrence. The limestone samples have a low Mn/Sr ratio (mostly <0.5) and lack a distinct correlation between δ13C and δ18O, indicating a low degree of diagenetic alteration. Our composite δ13C profile from the two limestone sections shows three stratigraphic correlation points that can be correlated with the profiles of relevant ages from the Alpine Tethyan region: a large‐amplitude fluctuation (the lower upper Kimmeridgian, ∼152 Ma), a positive anomaly (above the Kimmeridgian/Tithonian boundary, ∼150 Ma), and a negative anomaly (the upper lower Tithonian, ∼148 Ma). In addition, we found that δ13C values of the Torinosu‐type limestone are ∼1‰ lower than the Tethyan values in the late Kimmeridgian. This inter‐regional difference in δ13C values is likely to have resulted from a higher productivity and/or an organic burial in the Tethyan region. The difference gradually reduces and disappears in the late Tithonian, where the Tethyan and our δ13C records show similar stable values of 1.5–2.0‰. This isotopic homogenization is probably due to changes in the continental distribution and the global ocean circulation, which propagated the 13C‐depleted signature from the larger Paleo‐Pacific to the smaller Tethys Ocean during this time.

The Median Tectonic Line active fault system (MTL), with an average slip rate as high as 5-10 mm/yr, is one of the most active inland faults in Japan. However, the long-term seismic risk of the MTL has been poorly known, because of insufficient paleoseismological data, especially timing and displacement associated with the most recent surface faulting.We carried out a trench excavation survey across the Hatano fault in Doi town, Ehime Prefecture, and were able to precisely determine the timing of the latest faulting event. The survey site is located between range-facing fault scarps level 0.8 m high on an alluvial fan. We first excavated two trenches across the fault to precisely locate fault traces. Faults cutting Holocene sediment were exposed on both walls of each trench. The sense of apparent displacement across the fault zone is down to the south, which is consistent with fault scarps around the trench site. Then we excavated two trenches parallel to the fault zone to expose stratigraphic evidence of horizontal displacement associated with past earthquakes.The sediment exposed on the trench walls contains evidence of two faulting events in the past 3500 years B.P. The most recent surface faulting along the Hatano fault occurred between 1520 cal A.D and 1660 cal A.D. This is the first paleoseismological data that precisely constrain the timing of the most recent faulting event of the MTL. We have estimated 2.5 ± 0.5 m right-lateral displacement and 0.3-0.5 m vertical displacement up to the north during the most recent faulting event based on an offset of paleo-channel deposit.

Abstract. The apparatuses of Triassic ellisonid conodonts: Cornudina breviramulis, Hadrodontina aequabilis, and Staeschegnathus perrii gen. et sp. nov. from the Taho Formation in Higashiuwa-gun, Ehime Prefecture, Southwest Japan and Furnishius triserratus from the Iwai Formation in Nishitama-gun, Tokyo were reconstructed on the basis of the multielement structure of natural assemblages previously reported. Ellisonia triassica was remarked on this occasion. These species well agree with the general septimembrate apparatus structure containing 15 elements: angulate or pastinate P1, angulate P2, breviform digyrate M, alate S0, extensiform digyrate S1 and S2, and bipennate S3 and S4 elements. Having compared the morphologic features of apparatus elements of the Ellisonidae, I propose herein the new subfamily Hadrodontinae within it. Among the Ellisonidae and other taxa of the Prioniodinina, a phylogenetic relationship is recognized only between E. triassica and Upper Devonian Hibbardella angulata. Other speci...