Paleomagnetism of the Chibougamau greenstone belt,Quebec, and the effects of Grenvillian post-orogenic uplift     

H. Ueno  E. Irving 《Precambrian Research》1976,3(4):303-315

A paleomagnetic survey (34 sites, 200 core samples) of an Archean greenstone belt just north of the Grenville Front is described. Sixty per cent of the samples have blocking temperatures less than 400° C and remanent coercive forces predominantly below 100 Oe, and they provide no information about the Precambrian geomagnetic field. The other samples contain many magnetizations of which two (CS and CH) can be clearly recognized. The CS magnetization occurs in basic sills, and has high blocking temperature (550 to 650°C) and remanent coercive force (often exceeding 1000 Oe) and a direction (186°,?38°) that is not significantly different from that in Matachewan diabase dikes (2690 m.y.). CS is thought to have been caused by uplift following the Kenoran orogeny and its age is probably about 2600 m.y. No older magnetization has been found. The CH magnetization occurs in several different bodies and has a direction (119°, +51°) similar to that observed in rocks from other places close to the Grenville Front. CH has more variable blocking temperatures (200 to 650°C) and remanent coercive forces (200 to > 1000 Oe) and is considered to have been acquired by heating during uplift of the highly metamorphose Grenville Province to the south. Uplift occurred about 1000 m.y. ago, and the CH magnetization is considered to be of this age. Evidence is presented to support the suggestion that there was an extensive magnetization episode both within and adjacent to the Grenville Province at that time.  相似文献   

Classification of the Sibumasu and Paleo-Tethys tectonic division in Thailand using chert lithofacies     

Yoshihito  Kamata  Katsumi  Ueno  Hidetoshi  Hara  Megumi  Ichise  Thasinee  Charoentitirat  Punya  Charusiri  Apsorn  Sardsud  Ken-ichiro  Hisada 《Island Arc》2009,18(1):21-31

Two types of chert are defined in Thailand based on lithology, faunal content, and stratigraphy. 'Pelagic chert' consists of densely packed radiolarian tests in a microcrystalline quartz matrix with no terrigenous material and is found as blocks embedded within sheared matrix. 'Hemipelagic chert' also has a microcrystalline quartz matrix, and contains not only scattered radiolarian tests, but also calcareous organisms such as foraminifers. The pelagic cherts range in age from Devonian to Middle Triassic, whereas hemipelagic chert is only from the Early to the Late Triassic. Lithological and stratigraphic characteristics indicate that the pelagic chert originated in the Paleo-Tethys, whereas the hemipelagic chert accumulated on the eastern margin of the Sibumasu Block. The hemipelagic and pelagic chert are exposed in two north-trending belt-like zones. The western zone includes the hemipelagic chert, as well as glaciomarine and other Paleozoic to Mesozoic successions, overlying a Precambrian basement that consists exclusively of Sibumasu elements. The eastern zone contains pelagic chert and limestone and should be correlated to the Inthanon Zone. The Inthanon Zone is characterized by the presence not only of Paleo-Tethyan sedimentary rocks, but also of Sibumasu Block elements that structurally underlie the Paleo-Tethyan rocks. The boundary between the Sibumasu and Paleo-Tethys zones is a north-trending, low-angle thrust that resulted from the collision of the Sibumasu and Indochina blocks.  相似文献   

Investigating the Influence of Non‐Spectral Matrix Effects in the Determination of Twenty‐Two Trace Elements in Rock Samples by ICP‐QMS          下载免费PDF全文

Tetsuya Yokoyama  Yuichiro Nagai  Yu Hinohara  Tomohiko Mori 《Geostandards and Geoanalytical Research》2017,41(2):221-242

The influence of non‐spectral matrix effects on the determination of twenty‐two trace elements (Rb, Sr, Y, Cs, Ba, lanthanides, Pb, Th and U) in rock samples using ICP‐MS was investigated. Three types of multi‐element solutions were synthesised containing the twenty‐two trace elements, In, Tl and ten major rock‐forming elements with varying mass fractions mimicking the compositions of basalt, peridotite and dolomite. The synthetic solutions were conditioned to have dilution factors (DF) of 1000–10000. The extent of sensitivity suppression relative to the DF = 10000 solution became more significant for smaller DF solutions, which was not constant across different elements in a single solution but displayed general dependence on m/z. This indicates that at least two internal standards (e.g., In and Tl) are required for the correction of sensitivity variation. On the basis of the results, a new isotope dilution‐internal standardisation method for the determination of twenty‐two trace elements with ICP‐MS was developed, in which the sensitivity variation was corrected by monitoring two enriched isotopes, ¹¹³In and ²⁰³Tl. This method, coupled with the quantitative correction of interference from oxides and hydroxides, achieved precise determination of twenty‐two trace elements in some rock reference materials with reproducibilities of ±2% for basaltic to andesitic samples.  相似文献   

Phytoplankton community structure in Otsuchi Bay,northeastern Japan,after the 2011 off the Pacific coast of Tohoku Earthquake and tsunami     

Aiko Tachibana  Yuichiro Nishibe  Hideki Fukuda  Kyoko Kawanobe  Atsushi Tsuda 《Journal of Oceanography》2017,73(1):55-65

The tsunami caused by the 2011 off the Pacific coast of Tohoku Earthquake seriously damaged the Pacific coast of northeastern Japan. In addition to its direct disturbance, a tsunami can indirectly affect coastal pelagic ecosystems via topographical and environmental changes. We investigated seasonal changes in the phytoplankton community structure in Otsuchi Bay, northeastern Japan, from May 2011, which was 2 months after the tsunami, to May 2013. The phytoplankton species composition in May 2011 was similar to that observed in May 2012 and 2013. The present results are consistent with the dominant species and water-mass indicator species of phytoplankton in past records. These results suggest that there was no serious effect of the tsunami on the phytoplankton community in Otsuchi Bay. Community analysis revealed that two distinct seasonal communities appeared in each year of the study period. The spring–summer community was characterized by warm-water Chaetoceros species, and dinoflagellates appeared from May to September. The fall–winter community was characterized by cold neritic diatoms, which appeared from November to March. The succession from the spring–summer community to the fall–winter community took place within a particular water mass, and the fall–winter community appeared in both the surface water and the Oyashio water mass, suggesting that water-mass exchange is not the only factor that determines the phytoplankton community structure in Otsuchi Bay.  相似文献   

Asia-Pacific mussel watch: monitoring contamination of persistent organochlorine compounds in coastal waters of Asian countries   总被引：27，自引：0，他引：27  

Monirith I  Ueno D  Takahashi S  Nakata H  Sudaryanto A  Subramanian A  Karuppiah S  Ismail A  Muchtar M  Zheng J  Richardson BJ  Prudente M  Hue ND  Tana TS  Tkalin AV  Tanabe S 《Marine pollution bulletin》2003,46(3):281-300

Contamination of persistent organochlorines (OCs) such as PCBs (polychlorinated biphenyls), DDT and its metabolites (DDTs), HCH (hexachlorocyclohexane) isomers (HCHs), chlordane compounds (CHLs), and HCB (hexachlorobenzene) were examined in mussels collected from coastal waters of Asian countries such as Cambodia, China, Hong Kong, India, Indonesia, Japan, Korea, Malaysia, Philippines, Far East Russia, Singapore, and Vietnam in 1994, 1997, 1998, 1999, and 2001 to elucidate the contamination status, distribution and possible pollution sources and to assess the risks on aquatic organisms and human. OCs were detected in all mussels collected from all the sampling sites investigated. Considerable residue levels of p,p(')-DDT and alpha-HCH were found in mussels and the concentrations of DDTs and HCHs found in mussels from Asian developing countries were higher than those in developed nations suggesting present usage of DDTs and HCHs along the coastal waters of Asian developing countries. On the other hand, lower concentrations of PCBs detected in mussels from Asian developing countries than those in developed countries indicate that PCBs contamination in mussels is strongly related to industrial and activities. To our knowledge, this is a first comprehensive report on monitoring OCs pollution in the Asia-Pacific region.  相似文献   

Exact solution of a line-transfer problem in kernel approximation     

S. Ueno 《Astrophysics and Space Science》1974,30(1):35-41

In recent years approximate solutions for line-transfer problems using a kernel representation have been discussed by several authors (cf. Avrett and Loeser, 1966; Hummer and Rybicki, 1967). In this paper, extending an invariant imbedding method to the line-transfer problem with a kernel approximation as a sum of exponentials, we show how to get an exact solution of Milne's integral equation for the frequency-independent line source function with the aid of the resolvent kernel. A Cauchy system for an auxiliary function and the resolvent is suitable for numerical computation by means of high-speed digital computers.  相似文献   

Numerical results for Sobolev's function Q of radiative transfer     

J. Buell  R. Kalaba  S. Ueno 《Astrophysics》1971,7(1):12-20

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An inverse problem in a three-dimensional radiative transfer     

Alan P. Wang  Sueo Ueno 《Astrophysics and Space Science》1989,155(1):105-111

In a series of papers (cf. Bellmanet al., 1965a, b; Kagiwadaet al., 1975), an estimation of optical properties of turbid media has been made, in the least-squared sense, with the aid of quasi-linearization and invariant imbedding. Recently, an extension of the above procedure to the three-dimensional case with horizontally inhomogeneous albedo of the underlying surface has been attempted (Ueno, 1982). From computational aspects the numerical evaluation is not so easy, even by means of high-speed electronic computers. In the present paper it is shown that the latin-square algorithm is a useful estimate for the least-squares inference of the optical properties of turbid media bounded by an inhomogeneous reflecting surface.  相似文献   

Nutrient status of Otsuchi Bay (northeastern Japan) following the 2011 off the Pacific coast of Tohoku Earthquake     

Hideki Fukuda  Ryosuke Katayama  Yanhui Yang  Hiroyuki Takasu  Yuichiro Nishibe  Atsushi Tsuda  Toshi Nagata 《Journal of Oceanography》2016,72(1):39-52

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青藏高原那曲地区冰冰雹天气系统中的大气电场   总被引：12，自引：9，他引：3  

周筠 Kajik.  M 《高原气象》2000,19(3):339-347

利用１９９８年４～９月间进行的ＧＡＭＥ－ＴＩＢＥＴ青堪稿原云和降水的多普勒雷达及大气平均电场加强期观测实验资料,对青藏高原那曲地区的冰雹天气系统中的大民电场作了定量观测和研究。结果表明：在降雹过程中大气电场强度基本上系统中的大气电场强度基本上均为负值,其峰值也均强于－２２ｋＶｍ＾－１;在降雹过程中随着降雹时间的临近,大民场强度基本不断增强,但降雹开始时大气电场强度并不达到其峰值,峰值出现的时刻比开  相似文献