Longitudinally different variations of lower tropospheric carbon dioxide concentrations over the North Pacific Ocean     

TAKAKIYO NAKAZAWA  SHOHEI MURAYAMA  KOHJI MIYASHITA  SHUHJI AOKI  MASAYUKI TANAKA 《Tellus. Series B, Chemical and physical meteorology》1992,44(3):161-172

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Metamorphic Petrology of the Northern Tokoro Metabasites, Eastern Hokkaido, Japan     

SAKAKIBARA  MASAYUKI 《Journal of Petrology》1991,32(2):333-364

The metabasites within the Tokoro belt of eastern Hokkaido,Japan, suffered pervasive high–P/ Tetamorphism. Mineralassemblages and compositions of more than 400 metabasites fromthe Saroma–Tokoro district were investigated. The metabasites are divided into six metamorphic zones basedon mineral assemblages. The laumontite (Lm) zone is definedby the presence of laumontite. The prehnite–pumpellyite(Pr–Pp) zone is characterized by the association of prehnite+ pumpellyite. The lawsonite–sodic. pyroxene (Lw–Napx)zone is defined by the assemblage lawsonite + pumpellyite +sodic pyroxene + chlorite. The epidote–sodic pyroxene(Ep–Napx)(1) and (2) zones are charecterized by the assemblage epidote+ pumpellyite + sodic pyroxene + chlorite. The former is characterizedby the absence of aragonite, sodic amphibole, and winchite,as well as the presence of jadeite–poor sodic pyroxene(maxJd mol% = 13), whereas these minerals occur in the Ep–Napx(2)zone, together with jadeite–rich sodic pyroxene (max.Jd mol % = 34). In the epidote–actinolite (Ep–Act)zone, the most common assemblages contain epidote+ actionolite+ pumpellyite + chlorite. The Lm zone corresponds to the zeolite facies (150–200?Cand 1–2 kb) and the Pr–Pp zone is equivalent tothe prehnite–pumpellyite facies (200–250?C and 2–2–5kb). The Ep–Napx(I) zone appears to be stable at 200–250?C and 2? 5?3?5 kb. The pressure conditions in the Lw–Napx,Ep-Napx(2), and Ep–Act zones appear to range from 5 to6 kb, and the temperatures are estimated to be 200–230,230–270, and 270–300? C, respectively. The sequenceof the metamorphic zones is charaterized by the curved P–Tpath. The stability field of pumpellyite+ sodic+ pyroxene+ chloritein Fe₃+ bearing metabasites is located in the lower–temperatureand higher–pressure part of the pumpellyite–actionolitefacies. On the basis of Schreinmaker's method, the stabilityfield of the assemblage is bounded by a high–pressurereaction Pp+ Napx+ Chl+ Ab+ Qz+ H₂O= Lw+ Gl, and by a high-temperaturereaction Pp Napx+ Chl+ Ab+ Qz = Ep + Gl + H₂O.  相似文献   

Simulation of CO<Subscript> <Emphasis Type="Bold">2</Emphasis> </Subscript> concentrations at Tsukuba tall tower using WRF-CO<Subscript> <Emphasis Type="Bold">2</Emphasis> </Subscript> tracer transport model     

SRABANTI BALLAV  PRABIR K PATRA  YOUSUKE SAWA  HIDEKAZU MATSUEDA  AHORO ADACHI  SHIGERU ONOGI  MASAYUKI TAKIGAWA  UTPAL K DE 《Journal of Earth System Science》2016,125(1):47-64

Simulation of carbon dioxide (CO₂) at hourly/weekly intervals and fine vertical resolution at the continental or coastal sites is challenging because of coarse horizontal resolution of global transport models. Here the regional Weather Research and Forecasting (WRF) model coupled with atmospheric chemistry is adopted for simulating atmospheric CO₂ (hereinafter WRF-CO₂) in nonreactive chemical tracer mode. Model results at horizontal resolution of 27 × 27 km and 31 vertical levels are compared with hourly CO₂ measurements from Tsukuba, Japan (36.05°N, 140.13 ^oE) at tower heights of 25 and 200 m for the entire year 2002. Using the wind rose analysis, we find that the fossil fuel emission signal from the megacity Tokyo dominates the diurnal, synoptic and seasonal variations observed at Tsukuba. Contribution of terrestrial biosphere fluxes is of secondary importance for CO₂ concentration variability. The phase of synoptic scale variability in CO₂ at both heights are remarkably well simulated the observed data (correlation coefficient >0.70) for the entire year. The simulations of monthly mean diurnal cycles are in better agreement with the measurements at lower height compared to that at the upper height. The modelled vertical CO₂ gradients are generally greater than the observed vertical gradient. Sensitivity studies show that the simulation of observed vertical gradient can be improved by increasing the number of vertical levels from 31 in the model WRF to 37 (4 below 200 m) and using the Mellor–Yamada–Janjic planetary boundary scheme. These results have large implications for improving transport model simulation of CO₂ over the continental sites.  相似文献   

A newly discovered high-pressure terrane in eastern Hokkaido, Japan     

MASAYUKI SAKAKIBARA 《Journal of Metamorphic Geology》1986,4(4):401-408

Abstract The upper Jurassic Nikoro greenstone complex of eastern Hokkaido suffered high-pressure intermediate type metamorphism. Characteristic minerals include lawsonite, aragonite, sodic pyroxene of the aegirinejadeite series, winchite. sodic amphibole of the glaucophane-riebeckite series, pumpellyite, epidote and actinolite.
High-pressure metamorphism of the Nikoro greenstone complex is related to subduction of the Kula plate toward the Palaeo-Okhotsk Land during Cretaceous time.  相似文献   

The Kamuikotan zone in Hokkaido, Japan: tectonic mixing of high-pressure and low-pressure metamorphic rocks   总被引：1，自引：0，他引：1  

HIDEO ISHIZUKA  MASAYUKI IMAIZUMI  NOBUO GOUCHI  SHOHEI BANNO 《Journal of Metamorphic Geology》1983,1(3):263-275

Abstract. In the Kamuikotan zone, central Hokkaido, Japan, two distinct types of metamorphic rocks are tectonically mixed up, along with a great quantity of ultramafic rocks; one type consists of high-pressure metamorphic rocks, and the other of low-pressure ones. The high-pressure metamorphic rocks are divided into two categories. (1) Prograde greenschist to glaucophaneschist facies rocks derived from mudstone, sandstone, limestone, a variety of basic rocks such as pillow and massive lavas, hyaloclastite and tuff, and radiolarian (Valanginian to Hauterivian) chert, among which the basic rocks and the chert, and occasionally the sandstone, occur as incoherent blocks (or inclusions) enveloped by mudstone. (2) Retrograde amphibolites with minor metachert and glaucophane-calcite rock, which are tectonic (or exotic) blocks enclosed within prograde mudstone or serpentinite, or separated from these prograde rocks by faults. The K-Ar ages of the prograde metamorphic rocks (72, 107 and 116 Ma on phengitic muscovites) are younger than those of the retrograde rocks (109, 132, 135 and 145 Ma on muscovites, and 120 Ma on hornblende). The low-pressure metamorphic rocks consist of the mafic members of an ophiolite sequence with a capping of radiolarian (Tithonian) chert with the metamorphic grade ranging from the zeolite facies, through the greenschist (partly, actinolite-calcic plagioclase) facies to the amphibolite (partly, hornblende-granulite) facies. The low-pressure metamorphism has a number of similarities with that described for'ocean-floor'metamorphism. The tectonic evolution of such a mixed-up zone is discussed in relation to Mesozoic plate motion.  相似文献