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141.
142.
Penang Island represents the northwestern extension of the western magmatic belt of Peninsular Malaysia. Thirty-one samples of highly evolved biotite-and biotite-muscovite granites were used in an integrated study to unravel the complex magmatic, tectonic and cooling histories of these rocks. Highly distorted Rb–Sr whole-rock age patterns are evident. These are attributed to the partial post-magmatic Sr homogenization within the granite batholith which led to the rotation of isochrons towards younger ages and higher (87/86)Sr intercepts. The recognition of this mechanism allowed the establishment of a new Rb–Sr interpretation model. The intrusion ages of the granites can be extrapolated based on the evolutionary trend of the initial (87/86)Sr. Including the data of Bignell and Snelling, three episodes of granite emplacement at 307±8 Ma, 251±7 Ma and 211±2 Ma are suggested for Penang and the NW Main Range. The late-Triassic intrusive induced a hydrothermal conductive convection system which affected all the granites. It is considered to be responsible for the Rb–Sr whole-rock age distortion, the Rb–Sr and K–Ar biotite age resetting and the textural and mineralogical changes in the granites. The duration of the hydrothermal convections, deduced from the Rb–Sr whole rock ages, is about 6 Ma and 20 Ma in the northern and southern parts of Penang respectively. Fast regional cooling to 350±50°C within a time span of 1–3 Ma is recognized for the late-Triassic Feringgi intrusive from the mica ages, followed by a generally slow cooling rate of about 1°C/Ma. Fission track ages, in addition, indicate blockwise uplift along the N-S and NW-SE tending faults, thus resulting in the exposure of deeper crustal levels in southern and eastern Penang. A change in the tensional regime since Oligocene/Miocene, accompanied by a southwest tilting of the island, is indicated by the fission track apatite ages. Variable sometimes younger K–Ar, respectively Rb–Sr biotite ages mainly depend on the degree of hydrothermal overprint at different crustal levels. An increase of the reaction surface by grain size reduction influences Rb–Sr and K–Ar mica ages in similar ways, as has been demonstrated by experimental data. 相似文献
143.
Rounded and indented bedrock fragments amongst pyroclastics are evidence of fluidisation during maar eruption. Some fragments also show shrinkage cracks caused by volcanic heat. Compaction of bedding may form striated cone-like features after deposition. 相似文献
144.
Zhenhong Du Sensen Wu Mei-Po Kwan Chuanrong Zhang Feng Zhang Renyi Liu 《International journal of geographical information science》2018,32(10):1927-1947
Spatiotemporal kriging (STK) is recognized as a fundamental space-time prediction method in geo-statistics. Spatiotemporal regression kriging (STRK), which combines space-time regression with STK of the regression residuals, is widely used in various fields, due to its ability to take into account both the external covariate information and spatiotemporal autocorrelation in the sample data. To handle the spatiotemporal non-stationary relationship in the trend component of STRK, this paper extends conventional STRK to incorporate it with an improved geographically and temporally weighted regression (I-GTWR) model. A new geo-statistical model, named geographically and temporally weighted regression spatiotemporal kriging (GTWR-STK), is proposed based on the decomposition of deterministic trend and stochastic residual components. To assess the efficacy of our method, a case study of chlorophyll-a (Chl-a) prediction in the coastal areas of Zhejiang, China, for the years 2002 to 2015 was carried out. The results show that the presented method generated reliable results that outperform the GTWR, geographically and temporally weighted regression kriging (GTWR-K) and spatiotemporal ordinary kriging (STOK) models. In addition, employing the optimal spatiotemporal distance obtained by I-GTWR calibration to fit the spatiotemporal variograms of residual mapping is confirmed to be feasible, and it considerably simplifies the residual estimation of STK interpolation. 相似文献
145.
An analytical model including the boundary-layer effect is developed to find the steady drift induced by the non-linear effect of the surface-wave motion. The analytical result is compared with the experimental results obtained from a wave tank. Results show a qualitative agreement. A semi-empirical formula which predicts drift velocity of a contaminant layer on the free surface is introduced and its validity is investigated. 相似文献
146.
Cai Yuebo Kwan Kwokhung Cheung Yaukai Chan Honchuen
Senior Engineer Material Structure Department Nanjing Hydraulic Research Institute Nanjing P. H. Doctor 《中国海洋工程》1995,(3)
- With the modern development of chemical and mineral admixtures, it is now possible to produce much higher performance concrete than before. Higher performance does not only mean higher strength, but also better durability, lower risk of thermal cracking and higher dimensional stability etc. The three most effective admixtures for producing high performance concrete are superplastieizer, pulverized fuel ash and condensed silica fume. This paper outlines the properties of these materials and presents some practical guidelines for their usage. 相似文献
147.
Takeshi Kawano Michio Aoyama Terry Joyce Hiroshi Uchida Yasushi Takatsuki Masao Fukasawa 《Journal of Oceanography》2006,62(6):777-792
An updated batch-to-batch difference table of IAPSO standard seawater (SSW) up to P145 is proposed. The batch-to-batch difference
table is based on several recent SSW comparison experiments, including the experiments conducted independently at the Japan
Agency for Marine-Earth Science and Technology (JAMSTEC) and Woods Hole Institute of Oceanography (WHOI) at about the same
time using the same procedure. Proposed batch-to-batch differences range from 1.2 × 10−3 to −1.9 × 10−3 with reference to the average of those from P91 to P102. Batch-to-batch differences from P29 to P145 with reference to the
recent batches and this average over every 5 years since 1960 are also presented, together with standard deviation. This reveals
that inconsistency among batches has improved since 1980s. In particular, the standard deviation was 0.3 × 10−3 in this decade, which is about one-half the value reported previously and almost equal to the modern measurement precision
(0.2 × 10−3) and is within-batch difference (<0.3 × 10−3). Proposed batch-to-batch differences were applied to the observational results of the WOCE hydrographic onetime section
(WHP onetime) in the Indian Ocean. Average absolute salinity differences at 14 crossover points in the Indian Ocean were slightly
larger, from 1.2 × 10−3 to 1.5 × 10−3, when the batch-to-batch difference table was applied; however, when results from the Indian, Pacific, and Atlantic Oceans
were combined, application of the batch-to-batch difference table yielded statistically acceptable salinity differences. The
table was also applied to WHP sections P1 and P17 (revisited about 10 years after the original observations during the WOCE
period) and sections I1, I7, and I8 (visited twice by different research vessels in the same year). In all cases, the table
corrected unrealistically large salinity changes in space and time. The results suggest that the application of the batch-to-batch
table to well-controlled salinity data such as WOCE datasets would be effective in making the datasets more consistent in
space and time. 相似文献
148.
Hydrographic Structure and Transport of Intermediate Water in the Kuroshio Region off the Boso Peninsula, Japan 总被引:1,自引:1,他引:1
Kosei Komatsu Yutaka Hiroe Ichiro Yasuda Kiyoshi Kawasaki Terrence M. Joyce Frank Bahr 《Journal of Oceanography》2004,60(2):487-503
Hydrographic structure and transport of intermediate water were observed in the Kuroshio region south of Japan, focusing on
the 26.6–27.5σθ density in six cruises from May 1998 through September 2001. In the section off the Boso Peninsula where the Kuroshio exfoliates
eastward, the intermediate water was clearly clustered into three groups meridionally composed of the coastal water, the Kuroshio
water and the offshore water. Compared with the Kuroshio water characterized by warm, salty water transported by the Kuroshio,
the coastal and offshore waters significantly degenerated due to mixing with cold, fresh waters originated from the subarctic
region: the former was affected by alongshore spread of the coastal Oyashio and the latter by direct intrusion of the new
North Pacific Intermediate Water (NPIW) into the southern side of the Kuroshio current axis. Particularly the offshore water
showed higher apparent oxygen utilization (AOU) in layers deeper than 26.9σθ while it showed lower AOU in layers shallower than 26.9σθ, which indicated that colder, fresher and higher AOU water was distributed on the southeastern side of the Kuroshio in deeper
layers. In May 1998, the Oyashio-Kuroshio mixing ratio was estimated to be typically 2:8 for the offshore water on the assumption
of isopycnal mixing. Moreover, northeastward volume transport of the Kuroshio water was obtained from geostrophic velocity
fields adjusted to lowered acoustic Doppler current profiler (LADCP) data to yield 6.1 Sv at 26.6–26.9σθ and 11.8 Sv at 26.9–27.5 σθ.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
149.
Potential Orthopyroxene,Clinopyroxene and Olivine Reference Materials for In Situ Lithium Isotope Determination 总被引:1,自引:0,他引:1 下载免费PDF全文
Ben‐Xun Su Xiao‐Yan Gu Etienne Deloule Hong‐Fu Zhang Qiu‐Li Li Xian‐Hua Li Nathalie Vigier Yan‐Jie Tang Guo‐Qiang Tang Yu Liu Kwan‐Nang Pang Aaron Brewer Qian Mao Yu‐Guang Ma 《Geostandards and Geoanalytical Research》2015,39(3):357-369
Over 1400 electron probe and 700 ion probe microanalyses were performed on eleven mineral separates to evaluate their potential as reference materials for in situ Li isotopic determination. Our results suggest the homogenous distributions of major elements, Li and its isotopes for each sample. Hence, these samples are suitable to be used as reference materials for in situ measurements of Li abundance and Li isotopes by secondary ion mass spectrometry (SIMS) or laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS). These samples have the advantage of mitigating probable matrix effects during calibration owing to the wide range of compositions. The effect of composition on the δ7Li of olivine measured by SIMS is a linear function of composition, with δ7Li increasing by 1.0‰ for each mole per cent decrease in forsterite component. 相似文献
150.
Considering that urban areas may suffer more substantial losses than riparian farmlands during floods, diverting floodwater into riparian areas for temporal detention is expected to mitigate flood damage in downstream urban areas. In this study, an assessment has been conducted to evaluate the effect of flood mitigation through riparian detention in response to a changing climate in the Tou-Chien River basin of Taiwan. An integrated 1D–2D flow model was used to simulate the movement of flood wave in the main stream and the overbank flow inundating into the nearby lowlands. Based on the numerical simulation results, the flooding extents in the basin corresponding to different return periods of flood using existing flood prevention infrastructures were investigated. A detention strategy by lowering the levee along the riparian farmlands was proposed to avoid severe flooding in the densely populated urban areas of the basin. Research findings showed that the proposed detention measure can completely protect the downstream areas from overbank flooding when a flood having 20-yr period occurs, and can effectively alleviate the downstream flooding area from 27.4 to \(7.6\,\hbox {km}^{2}\) for a flood possessing 200-yr period. 相似文献