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51.
Roughness length for heat over an urban canopy 总被引:1,自引:0,他引:1
The roughness length for heat zT was evaluated over an urban canopy, using the measured sensible heat flux and radiometric temperature. To overcome thermal heterogeneity in the urban area, the measured radiometric temperature was transformed into the equivalent temperature of an upward longwave radiation flux. The equivalent temperature was found to provide an effective parameterization of the radiometric temperature. The daytime average of the resulting ln(zT/z0) was 10, where z0 is the aerodynamic roughness length. This result generally agrees with previous studies; however, the anthropogenic heat is a large uncertainty, which could cause an error at least 240% in zT. 相似文献
52.
Electrokinetic phenomena associated with a water injection experiment at the Nojima fault on Awaji Island, Japan 总被引:2,自引:0,他引:2
Hideki Murakami Takeshi Hashimoto Naoto Oshiman Satoru Yamaguchi Yoshimori Honkura Norihiko Sumitomo 《Island Arc》2001,10(3-4):244-251
Abstract Self-potential variations were measured to estimate the magnitude of electrokinetic and hydrological parameters (zeta potential and permeability) of the Nojima Fault zone in Awaji, Japan. The study observed self-potential variations that seemed to be associated with water flow from the injection well to the fracture zone, which were induced by turning the injection on and off. Amplitudes of the variations were a few to 0.03 V across 320–450 m dipoles. These variations can be explained well with an electrokinetic model. The quantity k/ζ (permeability/zeta potential) is in the range 1.6 × 10−13 − 5.4 × 10−13 m2 /V. Permeability of the Nojima fault zone can be estimated as approximately 10−16 –10−15 m2 on the assumption that the zeta potential is in the range –0.01 to –0.001 V. 相似文献
53.
Harutaka Sakai Minoru Sawada Yutaka Takigami Yuji Orihashi Tohru Danhara Hideki Iwano Yoshihiro Kuwahara Qi Dong Huawei Cai Jianguo Li 《Island Arc》2005,14(4):297-310
Abstract Newly discovered peloidal limestone from the summit of Mount Qomolangma (Mount Everest) contains skeletal fragments of trilobites, ostracods and crinoids. They are small pebble-sized debris interbedded in micritic bedded limestone of the Qomolangma Formation, and are interpreted to have been derived from a bank margin and redeposited in peri-platform environments. An exposure of the Qomolangma detachment at the base of the first step (8520 m), on the northern slope of Mount Qomolangma was also found. Non-metamorphosed, strongly fractured Ordovician limestone is separated from underlying metamorphosed Yellow Band by a sharp fault with a breccia zone. The 40 Ar–39 Ar ages of muscovite from the Yellow Band show two-phase metamorphic events of approximately 33.3 and 24.5 Ma. The older age represents the peak of a Barrovian-type Eo-Himalayan metamorphic event and the younger age records a decompressional high-temperature Neo-Himalayan metamorphic event. A muscovite whole-rock 87 Rb–86 Sr isochron of the Yellow Band yielded 40.06 ± 0.81 Ma, which suggests a Pre-Himalayan metamorphism, probably caused by tectonic stacking of the Tibetan Tethys sediments in the leading margin of the Indian subcontinent. Zircon and apatite grains, separated from the Yellow Band, gave pooled fission-track ages of 14.4 ± 0.9 and 14.4 ± 1.4 Ma, respectively. These new chronologic data indicate rapid cooling of the hanging wall of the Qomolangma detachment from approximately 350°C to 130°C during a short period (15.5–14.4 Ma). 相似文献
54.
Asbjrn Johan Breivik Rolf Mjelde Paul Grogan Hideki Shimamura Yoshio Murai Yuichi Nishimura 《Tectonophysics》2005,401(1-2):79-117
The western Barents Sea and the Svalbard archipelago share a common history of Caledonian basement formation and subsequent sedimentary deposition. Rock formations from the period are accessible to field study on Svalbard, but studies of the near offshore areas rely on seismic data and shallowdrilling. Offshore mapping is reliable down to the Permian sequence, but multichannel reflection seismic data do not give a coherent picture of older stratigraphy. A survey of 10 Ocean Bottom Seismometer profiles was collected around Svalbard in 1998. Results show a highly variable thickness of pre-Permian sedimentary strata, and a heterogeneous crystalline crust tied to candidates for continental sutures or major thrust zones. The data shown in this paper establish that the observed gravity in some parts of the platform can be directly related to velocity variations in the crystalline crust, but not necessarily to basement or Moho depth. The results from three new models are incorporated with a previously published profile, to produce depth-to-basement and -Moho maps south of Svalbard. There is a 14 km deep basement located approximately below the gently structured Upper Paleozoic Sørkapp Basin, bordered by a 7 km deep basement high to the west, and 7–9 km depths to the north. Continental Moho-depth range from 28 to 35 km, the thickest crust is found near the island of Hopen, and in a NNW trending narrow crustal root located between 19°E and 20°E, the latter is interpreted as a relic of westward dipping Caledonian continental collision or major thrusting. There is also a basement high on this trend. Across this zone, there is an eastward increase in the VP, VP/VS ratio, and density, indicating a change towards a more mafic average crustal composition. The northward basement/Moho trend projects onto the Billefjorden Fault Zone (BFZ) on Spitsbergen. The eastern side of the BFZ correlates closely with coincident linear positive gravity and magnetic anomalies on western Ny Friesland, apparently originating from an antiform with high-grade metamorphic Caledonian terrane. A double linear magnetic anomaly appears on the BFZ trend south of Spitsbergen, sub-parallel to and located 10–50 km west of the crustal root. Based on this correlation, it is proposed that the suture or major thrust zone seen south of Svalbard correlates to the BFZ. The preservation of the relationship between the crustal suture, the crustal root, and upper mantle reflectivity, challenges the large-offset, post-collision sinistral transcurrent movement on the BFZ and other trends proposed in the literature. In particular, neither the wide-angle seismic data, nor conventional deep seismic reflection data south of Svalbard show clear signs of major lateral offsets, as seen in similar data around the British Isles. 相似文献
55.
Colin M. Graham John W. Valley John M. Eiler Hideki Wada 《Contributions to Mineralogy and Petrology》1998,132(4):371-389
Using a recently developed ion microprobe technique, a detailed oxygen isotope map of calcite grains in a coarse-grained
marble has been constructed, supported by trace element (Mn, Sr, Fe) analysis and cathodoluminescence (CL) imaging, in order
to constrain scales of oxygen isotope equilibrium, timescales and mechanisms of metamorphic fluid infiltration, and fluid
sources and pathways. Results are compared with a previous study of this sample (Wada 1988) carried out using a cryo-microtome
technique and conventional oxygen isotope analysis. The marble, from the high temperature/low pressure Hida metamorphic belt
in north-central Japan, underwent granulite facies followed by amphibolite facies metamorphic events, the latter associated
with regional granite intrusion. The CL imaging indicates two types of calcite, a yellow luminescing (YLC) and a purple luminescing
(PLC) variety. The YLC, which occupies grain boundaries, fractures, replacement patches, and most of the abundant deformation
twin lamellae, post-dates the dominant PLC calcite and maps out fluid pathways. Systematic relationships were established
between oxygen isotope and trace element composition, calcite type and texture, based on 74 18O/16O and 17 trace element analyses with 20–30 μ m spatial resolution. The YLC is enriched in Mn and Fe, and depleted in 18O and Sr compared to PLC, and is much more 18O depleted than is indicated from conventional analyses. Results are interpreted to indicate infiltration of 18O-depleted (metamorphic or magmatic) fluid (initial δ18O = 9‰–10.5‰) along grain boundaries, fractures and deformation twin lamellae, depleting calcite grains in Sr and enriching
them in Mn and Fe. The sample is characterised by gross isotopic and elemental disequilibrium, with important implications
for the application of chromatographic theory to constrain fluid fluxes in metacarbonate rocks.
Areas of PLC unaffected by “short-circuiting” fluid pathways contain oxygen diffusion profiles of ∼10‰/∼200 μm in grain boundary
regions or adjacent to fractures/patches. When correction is made for estimated grain boundary/fracture and profile orientation
in 3D, profiles are indistinguishable within error. Modelling of these profiles gives consistent estimates of Dt (where D is the diffusion coefficient and t is time) of ∼0.8 × 10−8 m2, from which, using experimental data for oxygen diffusion in calcite, timescales of fluid transport along grain boundaries
at amphibolite facies temperatures of ∼103 to ∼104 years are obtained. These short timescales, which are much shorter than plausible durations of metamorphism, imply that
rock permeabilities may be transiently much higher during fluid flow than those calculated from time integrated fluid fluxes
or predicted from laboratory measurements. The preservation of 18O/16O profiles requires either rapid cooling rates (∼100–600 °C/million years), or, more plausibly, loss of grain boundary fluid
such that a dry cooling history followed the transient passage of fluid. The δ18O/trace element correlations are also consistent with volume diffusion-controlled transport in the PLC. Fluid transport and
element exchange occurred by two inter-related mechanisms on short timescales and on different lengthscales – long-distance
flow along cracks, grain boundaries and twin lamellae coupled to ∼200 μm-scale volume diffusion of oxygen.
Received: 8 December 1997 / Accepted: 18 May 1998 相似文献
56.
57.
Hideki Shimamura Morio Ino Hisayoshi Hikawa Takaya Iwasaki 《Pure and Applied Geophysics》1984,122(6):933-946
Microtemperature measurements of groundwater with a relative precision better than 1/1000°C have been made in several seismically active areas in Japan. The measured temperatures show clear coseismic signals as well as a correlation with atmospheric pressure. Simultaneous observations at various depths have shown that these temperature changes were not induced by simple groundwater level changes. Also, distinctive signals occurred before several earthquakes and seem to be caused by a different mechanism than the coseismic signals. The microtemperature at some observation sites shows excellent correlation with records of nearby sensitive borehole strainmeters. Simultaneous recording of microtemperature and strain has been initiated in some boreholes. 相似文献
58.
Takeshi Naganuma C. Julius Meisel Hideki Wada Yukihiro Kato Akira Takeuchi Katsunori Fujikura Jiro Naka & Kantaro Fujioka 《Island Arc》1999,8(2):232-244
A biological community was discovered in the Northern Okushiri Ridge, northeastern Japan Sea. The community was closely associated with sea-floor fissures, and presumed to be supported by methanotrophic and/or thiotrophic bacterial production. Sediments inside of and in the vicinity of the fissures were collected, and the short-chain (C9–20 ) sediment fatty acids were analyzed for amounts and compositions. The fatty acid compositions were compared with those from a known methane seep and a submarine volcano in the Sagami Bay, central Japan, and from a whale skeleton at the Torishima Seamount, northwestern Pacific Ocean. As a result, a close relationship between the sediments from the Northern Okushiri Ridge, the known methane-seep, and the whale skeleton was found. This finding represents the first discovery of methane seepage and associated biological communities in the Japan Sea. This also supports the hypothesis that the eastern margin of the northern Japan Sea is at the early stage of new subduction. 相似文献
59.
60.
Detrital zircon multi‐chronology,provenance, and low‐grade metamorphism of the Cretaceous Shimanto accretionary complex,eastern Shikoku,Southwest Japan: Tectonic evolution in response to igneous activity within a subduction zone 下载免费PDF全文
Hidetoshi Hara Yoshihiro Nakamura Kousuke Hara Toshiyuki Kurihara Hiroshi Mori Hideki Iwano Tohru Danhara Shuhei Sakata Takafumi Hirata 《Island Arc》2017,26(6)
Detrital zircon multi‐chronology combined with provenance and low‐grade metamorphism analyses enables the reinterpretation of the tectonic evolution of the Cretaceous Shimanto accretionary complex in Southwest Japan. Detrital zircon U–Pb ages and provenance analysis defines the depositional age of trench‐fill turbidites associated with igneous activity in provenance. Periods of low igneous activity are recorded by youngest single grain zircon U–Pb ages (YSG) that approximate or are older than the depositional ages obtained from radiolarian fossil‐bearing mudstone. Periods of intensive igneous activity recorded by youngest cluster U–Pb ages (YC1σ) that correspond to the younger limits of radiolarian ages. The YC1σ U–Pb ages obtained from sandstones within mélange units provide more accurate younger depositional ages than radiolarian ages derived from mudstone. Determining true depositional ages requires a combination of fossil data, detrital zircon ages, and provenance information. Fission‐track ages using zircons estimated YC1σ U–Pb ages are useful for assessing depositional and annealing ages for the low‐grade metamorphosed accretionary complex. These new dating presented here indicates the following tectonic history of the accretionary wedge. Evolution of the Shimanto accretionary complex from the Albian to the Turonian was caused by the subduction of the Izanagi plate, a process that supplied sediments via the erosion of Permian and Triassic to Early Jurassic granitic rocks and the eruption of minor amounts of Early Cretaceous intermediate volcanic rocks. The complex subsequently underwent intensive igneous activity from the Coniacian to the early Paleocene as a result of the subduction of a hot and young oceanic slab, such as the Kula–Pacific plate. Finally, the major out‐of‐sequence thrusts of the Fukase Fault and the Aki Tectonic Line formed after the middle Eocene, and this reactivation of the Shimanto accretionary complex as a result of the subduction of the Pacific plate. 相似文献