Process length variation of the cyst of the dinoflagellate Protoceratium reticulatum in the North Pacific and Baltic‐Skagerrak region: calibration as an annual density proxy and first evidence of pseudo‐cryptic speciation     

Kenneth Neil Mertens  Manuel Bringué  Nicolas Van Nieuwenhove  Yoshihito Takano  Vera Pospelova  Andre Rochon  Anne De Vernal  Taoufik Radi  Barrie Dale  R. Timothy Patterson  Kaarina Weckström  Elinor Andrén  Stephen Louwye  Kazumi Matsuoka 《第四纪科学杂志》2012,27(7):734-744

Process length variation of cysts of the dinoflagellate Protoceratium reticulatum (Claparède et Lachmann) Bütschli in surface sediments from the North Pacific was investigated. The average process length showed a significant inverse relation to annual seawater density: σ_{t annual} = ?0.8674 × average process length + 1029.3 (R² = 0.84), with a standard error of 0.78 kg m^?3. A sediment trap study from Effingham Inlet in British Columbia revealed the same relationship between average process length and local seawater density variations. In the Baltic–Skagerrak region, the average process length variation was related significantly to annual seawater density: σ_{t annual} = 3.5457 × average process length ? 993.28 (R² = 0.86), with a standard error of 3.09 kg m^?3. These calibrations cannot be reconciled, which accentuates the regional character of the calibrations. This can be related to variations in molecular data (small subunit, long subunit and internal transcribed spacer sequences), which show the presence of several genotypes and the occurrence of pseudo‐cryptic speciation within this species. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

泰国北部Inthanon带外来硅质岩块的中、晚二叠世放射虫：对与古特提斯消减有关的混杂岩形成时代的约束     

Yoshihito KAMATA  Hidetoshi HARA  Katsumi UENO  Apsorn SARDSUD  Thasinee CHAROENTITIRAT  Punya CHARUSIRI  Ken-ichiro HISADA 《地球学报》2012,33(S1):36-37

The Inthanon Zone of Northern Thailand, origi-nally proposed by Barr and Macdonald (1991), is characterized by the occurrence of Paleo-Tethyan pe-lagic sediments including Carboniferous–Permian seamount-type carbonate associated with oceanic ba-saltic rocks and Middle Devonian–Middle Triassic radiolarian chert (Ueno, 1999; Ueno and Hisada, 2001; Ueno and Charoentitirat, 2011). These pelagic rocks have been mainly studied from the viewpoint of bio-stratigraphy to clarify the duration of their deposition. These studies concluded the Paleo-Tethys to be a vast ocean basin once existed between the Indochina and Sibumasu continental blocks during Devo-nian–Triassic times.  相似文献   

泰国北部三叠系Lampang群Doi Long组的有孔虫组合与沉积环境     

Akira MIYAHIGASHI  Katsumi UENO  Thasinee CHAROENTITIRAT  Yoshihito KAMATA 《地球学报》2012,33(S1):45-49

A rich foraminiferal assemblage, consisting of abundant Aulotortus sinuosus and A. tumidus in association with Lamelliconus multispirus, Endoteba ex gr. controversa, E. ex gr. badouxi, Endotebanella kocaeliensis, Endotriada tyrrhenica, Endotriadella wirzi, Malayspirina fontainei, Ammobaculites rhaeticus, Diplotremina astrofimbriata, Agathammina austroalpina, and others, was found in the Doi Long Formation of the Triassic Lampang Group, Northern Thailand. These foraminifers suggest that the formation is referable to the Carnian (early Late Triassic), which is consistent with the age estimated by ammonoids. In microfacies, peloidal grainstone, bioclastic grainstone, sponge-microbial boundstone, and oolitic grainstone were recognized in the Doi Long Formation. Based on microfacies, three depositional facies, the lagoon facies, reef facies, and shoal facies, are recognized in this formation. These lines of evidence are suggestive that the Doi Long Formation was deposited in a reef or bank setting rather than a ramp setting.  相似文献   

Concentrations of 137Cs, 90Sr, 108m Ag, 239+240 Pu and atom ratio of 240Pu/239Pu in tanner crabs, Chionoecetes japonicus and Chionoecetes opilio collected around Japan     

Morita T  Ohtsuka Y  Fujimoto K  Minamisako Y  Iida R  Nakamura M  Kayama T 《Marine pollution bulletin》2010,60(12):2311-2322

The anthropogenic radionuclides, ¹³⁷Cs, ⁹⁰Sr, ^108mAg, ^239+240Pu, were measured in two Chionoecetes species, red queen crab (Chionoecetes japonicus) and snow crab (Chionoecetes opilio) collected around Japan during 1996–2007. There was no increase in the concentrations of these radionuclides and no large variation of the atom ratio of ²⁴⁰Pu/²³⁹Pu during this research period. These results indicated that the source of the radionuclides was not the radioactive wastes dumped by the former USSR and Russia and originated from past nuclear weapon tests. The higher atom ratio in the crab species than that from global fallout would be contributed by the Pacific Proving Grounds close-in fallout. The variability of the concentration of radionuclides in the crab species would result from the variability of the composition and quantity in the diet. However, the decrease in the concentration of radionuclides with sampling depth would depend on the concentration in the seawater and diet.  相似文献   

Opening and closing process of the Paleo-Tethys in Northern Thailand     

Hidetoshi HARA  Koji WAKITA  Jun-ichiro KURODA  Toshiyuki KURIHARA  Katsumi UENO  Yoshihito KAMATA  Ken-ichiro HISADA  Punya CHARUSIRI  Thasinee CHAROENTITIRAT  Pol CHAODUMRONG 《地球学报》2009,30(Z1):12-12

The Paleo-Tethys formed a large ocean basin that existed between Laurasia and Gondwana during Late Paleozoic to Early Mesozoic times. It opened in the Early Devonian by the rifting of Gondwanaland and closed at around latest Triassic time by the collision of the Cimmerian continent to Laurasia (Metcalfe, 1999). We reconstructed opening and closing process of the Paleo-Tethys in Northern Thailand.  相似文献   

The role of crabs (Macrophthalmus japonicus) burrows on organic carbon cycle in estuarine tidal flat,Japan     

Sosuke Otani  Yasunori Kozuki  Ryoichi Yamanaka  Hiromitsu Sasaoka  Tetsu Ishiyama  Yoshihito Okitsu  Hajime Sakai  Yoji Fujiki 《Estuarine, Coastal and Shelf Science》2010,86(3):434-440

The objective of this study is to elucidate the burrow structure and to clarify the role of burrows in material cycle in the tidal flat. In our work, we focused on the dominant species in muddy tidal flat, crab Macrophthalmus japonicus.Burrow structure of Macrophthalmus japonicus was investigated on a Katsuura river tidal flat in Tokushima prefecture, Japan, using in situ resin casting. Sampling was conducted in August 2006, and a total of 48 burrow casts were obtained. Burrows consisted mainly of J-shaped structures (98%) while the rest belonged to U-shaped structures (2%). The maximum measured burrow volume was 120 cm³ and wall surface area was 224 cm², while maximum burrow length and depth were 23.2 cm and 16.5 cm, respectively. Burrow volume and surface area were strongly correlated with carapace width of M. japonicus. Investigation of the individual number of M. japonicus in 13 quadrats (50 × 50 × 20 cm) was conducted using 2 mm sieve. The number of M. japonicus was 15–31 ind./m². Using cohort analysis we estimated that surface area of burrows was 0.07–0.15 m²/m².CO₂ emission rate was measured at the surface sediment during the period from June to December 2008. Results varied from 13.8 ± 2.2 to 49.4 ± 3.2 mg CO₂/m²/h, and organic carbon decomposition was 3.8 ± 0.6–13.5 ± 0.9 mg C/m²/h. This leads the increase of organic carbon decomposition by 1.1 times, because of the expansion of the tidal flat surface area by burrowing activity. Organic carbon decomposition in burrow walls therefore contributed to organic matter decomposition in the tidal flat. These results indicated that in situ activities of Macrophthalmus japonicus significantly influence the material cycle and it is important to consider the existence of burrow in order to understand the fluxes of materials and to evaluate the purification function of the tidal flat.  相似文献   

泰国东南部Rayong省Klaeng地区的中-晚泥盆世放射虫     

Yoshihito KAMATA  Miyako KATO  Katsumi UENO  Akira MIYAHIGASHI  Thasinee CHAROENTITIRAT  Apsorn SARDSUD 《地球学报》2012,33(S1):33-35

Tectonic subdivision of mainland Thailand has been discussed by means of Paleozoic and Mesozoic stratigraphy, micropaleontology represented by fo-raminiferal and radiolarian biostratigraphy and paleo-biogeography, tectonic settings of granitoids, and ul-tramafic rocks that are distinctive of suture lines. Re-cently, Ueno (2002) and Ueno and Charoentitilat (2011) proposed a new tectonic scheme of mainland Thailand and divided it into three geotectonic units: the Sibu-masu Block, Sukhothai Zone, and Indochina Block from west to east, which are separated by the Mae Yuan Fault, the Chiang Rai Tectonic Line, and the Nan–Uttaradit Suture, respectively. In Northern Thai-land, moreover, the peculiar Inthanon Zone is recog-nized in the eastern part of the Sibumasu Block, where Paleo-Tethyan oceanic rocks are widely distributed as tectonic slices. These geotectonic subdivisions in Northern Thailand are relatively clear. However, the tectonic subdivisions of Central and Southeast Thai-land have not been well documented and are still con-troversial because there is short of information about basement rocks in those areas. In this circumstance, we have examined Paleozoic to Mesozoic stratigraphy, lithology, and radiolarian ages of siliceous rocks dis-tributed in Southeast Thailand to clarify the geotec-tonic belongings of this area and the southern exten-sions of geotectonic units consisting of Northern Thailand. In the course of this research, we could ob-tain Middle to Late Devonian radiolarians from well-bedded siliceous rocks distributed in southwest of Klaeng, Rayong Province. In this study, we report lithology and age of the radiolaria-bearing rocks and discuss their stratigraphy and geological correlation nearby the Klaeng region.  相似文献   

Storm-time characteristics of low-latitude whistlers     

Yoshihito Tanaka  Masashi Hayakawa 《Planetary and Space Science》1973,21(10):1797-1798

Using the results from special observations, the storm-time effects on whistler characteristics at low latitudes were examined and found to agree with previous statistical studies. A short discussion is made on the link between spread-F irregularities and magnetospheric whistler ducts. The enhanced whistler activity is explained as a consequence of the stable whistler duct region during spread-F conditions.  相似文献   

Early Permian ammonoids from the Kaeng Krachan Group of the Phatthalung-Hat Yai area, southern peninsular Thailand   总被引：1，自引：1，他引：1  

Masayuki Fujikawa  Katsumi Ueno  Apsorn Sardsud  Wirote Saengsrichan  Yoshihito Kamata  Ken-ichiro Hisada 《Journal of Asian Earth Sciences》2005,24(6):739

An Early Permian small ammonoid fauna consisting of Neocrimites sp., Agathiceras suessi Gemmellaro, A. girtyi Böse, Agathiceras? sp., and Miklukhoceras sp. was found in nodules of a fine sandstone bed exposed in the Phatthalung-Hat Yai area of southern peninsular Thailand. The ammonoid-bearing bed belongs stratigraphically to the uppermost part of the Kaeng Krachan Group, which is essentially a clastic-dominant, Late Carboniferous (?) to Early Permian stratigraphic unit, widely distributed in western and peninsular Thailand. This ammonoid fauna is considered to be of Bolorian (Kungurian) age and includes Agathiceras girtyi Böse, which is described for the first time from Thailand. The present discovery of Bolorian ammonoids suggests that the uppermost part of the Kaeng Krachan Group is slightly younger than previously considered and around the latest Early Permian. This further implies that the continental margin environment of the Sibumasu Block drastically changed at around Bolorian time from a cool, clastic-dominant shelf condition to a temperate to subtropical, carbonate platform due to rapid northward drift after middle Artinskian rifting.  相似文献   

Equatorial field-aligned irregularities deduced from the echo-train and hybrid whistlers     

Masashi Hayakawa  Yoshihito Tanaka 《Pure and Applied Geophysics》1973,111(1):2336-2340

Summary Equatorial field-aligned irregularities have been studied by using low-latitude echotrain and hybrid whistlers observed at Sakushima Station (geomag. lat. 24°). The structure is discussed in relation to the propagation mode trapped by field-aligned irregularities. We then find that the field-aligned irregularities responsible for the trapping of low latitude whistlers are of such small dimension as the HF ducts.  相似文献