On the relationship between mean monthly global radiation and air temperature     

Prof. Dr. Jen-hu Chang  Barry Root 《Theoretical and Applied Climatology》1975,23(1-2):13-30

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滨海滩涂全极化SAR影像相干斑滤波方法研究     

江畅 《测绘学报》1957,49(11):1510-1510

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Geochemical dispersion patterns of As, Sb, Bi and Se associated with sulfide mineralization at Avoca, Eire     

C.J. Moon  M. Hale 《Journal of Geochemical Exploration》1983,19(1-3)

At Avoca, Eire, Kuroko-like sulfide mineralization comprising massive stratiform cupriferous pyrite, accompanied by hanging-wall galena-sphalerite mineralization and footwall stringer pyrite, is hosted by Ordovician sediments, calc-alkaline lavas and pyroclastics. The sequence has been subjected to low-grade regional metamorphism, isoclinal folding and thrusting. The surficial cover comprises nonexotic glacial drift some 2 m thick. Previous work has demonstrated that major-element lithogeochemistry reflects the wall-rock alteration associated with the mineralization, but these signatures are absent from the overlying till. There is a poor heavy metal-expression at surface of the concealed mineralization.Analysis of wall rock, basal till and surface till samples for the chalcophile pathfinder elements As, Sb, Bi and Se (by rapid techniques which involve the introduction of their volatile hydrides into an inductively coupled plasma emission spectrometer) shows that a primary zonation of these elements around the mineralization can, in part, be traced to surface. In wall rocks, Bi enrichment is associated with the massive pyrite and footwall mineralization, Sb and Se anomalies occur in the hanging wall, and an As halo extends across all three types of mineralization. At surface, Bi and As anomalies are found over the massive pyrite and footwall zones, and an Sb anomaly occurs above the hanging-wall mineralization. The development of these patterns is attributed to mainly hydromorphic dispersion.The primary and surficial dispersion patterns of the chalcophile pathfinders should prove useful in exploration for other examples of Kuroko-type mineralization. The determination of these elements in geochemical exploration can be carried out quickly and cost-effectively.  相似文献   

Jurassic uplift and erosion of the northeast Queensland continental margin: evidence from (U–Th)/He thermochronology combined with U–Pb detrital zircon age spectra     

Y. Cheng  M. Danišík  F. Sahlström  Z. Chang 《Australian Journal of Earth Sciences》2020,67(4):591-604

Abstract

The Jurassic–Cretaceous Great Artesian Basin is the most extensive, and largest volume, sedimentary feature of continental Australia. The source of its mud-dominated Cretaceous infill is attributed largely to contemporary magmatism along the continental margin to the east, but the source of its Jurassic infill, dominated by quartz sandstone, remains unconstrained. This paper investigates the question of a Jurassic sediment source for the northern part of the basin. Jurassic uplift and exhumation of the continental margin crustal sector to the east provided the primary Jurassic sediment source. (U–Th)/He data are presented for zircon and apatite from Pennsylvanian to mid Permian granitoids of the Kennedy Igneous Association distributed within the northern Tasmanides between the Townsville and Cairns regions and for coeval granites of the Urannha batholith from the Mount Carlton district (N Bowen Basin), also within the northern Tasmanides. The data from zircon indicate widespread Jurassic exhumation of a crustal tract located to the east of the northern Great Artesian Basin and largely occupied by rocks of the Tasmanides. Detrital zircon age spectra for samples of the Jurassic Hutton and Blantyre sandstones from the northeastern margin of the Great Artesian Basin show their derivation to be largely from rocks of the northern Tasmanides. In combination, the detrital age spectra and (U–Th)/He data from zircon indicate exhumation owing to uplift generating appreciable physiographic relief along the north Queensland continental margin during the Jurassic, shedding sediment westward into the Great Artesian Basin during its early development. A portion of (U–Th)/He data for zircon are consistent with late Permian–mid Triassic exhumation within the Tasmanides, attributable to the influence of the Hunter--Bowen Orogeny. Evidence of Cretaceous and Paleocene exhumation episodes is also indicated for some samples, mainly by apatite (U–Th)/He analysis, consistent with data previously published from fission track studies. Overall, new data from the present study reveal that the exhumation related to Jurassic regional uplift and the subsequent erosional reworking of the northeast Australian continental margin is critical for the evolution and development of the northern side of the Great Artesian Basin in eastern Australia. Apart from this, another two previously suggested Permian–Triassic and Cretaceous exhumation and uplift episodes along the northeast Australian continental margin are also confirmed by the dataset of this study.

1. KEY POINTS

2. U–Pb detrital zircon ages of sandstone samples from the northeastern Eromanga Basin reveal Paleozoic (480–280 Ma) and Proterozoic (1800–1400 Ma) age clusters.

3. (U–Th)/He zircon and apatite dating results of granitoids samples from Cairns, Townsville and the Mount Carlton districts are dominated by Jurassic (198–164 Ma) and Permian–Triassic (272–238 Ma) age clusters.

4. Combination of above two datasets proves the regional uplift-driving Jurassic exhumation episode in the northeast Australian continental is vital for the development of the northern Great Artesian Basin.

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Air quality model performance evaluation   总被引：3，自引：0，他引：3  

J. C. Chang  S. R. Hanna 《Meteorology and Atmospheric Physics》2004,87(1-3):167-196

Summary This paper reviews methods to evaluate the performance of air quality models, which are tools that predict the fate of gases and aerosols upon their release into the atmosphere. Because of the large economic, public health, and environmental impacts often associated with the use of air quality model results, it is important that these models be properly evaluated.A comprehensive model evaluation methodology makes use of scientific assessments of the model technical algorithms, statistical evaluations using field or laboratory data, and operational assessments by users in real-world applications. The focus of the current paper is on the statistical evaluation component. It is important that a statistical model evaluation exercise should start with clear definitions of the evaluation objectives and specification of hypotheses to be tested. A review is given of a set of model evaluation methodologies, including the BOOT and the ASTM evaluation software, Taylors nomogram, the figure of merit in space, and the CDF approach. Because there is not a single best performance measure or best evaluation methodology, it is recommended that a suite of different performance measures be applied. Suggestions are given concerning the magnitudes of the performance measures expected of good models. For example, a good model should have a relative mean bias less than about 30% and a relative scatter less than about a factor of two.In order to demonstrate some of the air quality model evaluation methodologies, two simple baseline urban dispersion models are evaluated using the Salt Lake City Urban 2000 field data. The importance of assumptions concerning details such as minimum concentration and pairing of data are shown. Typical plots and tables are presented, including determinations of whether the difference in the relative mean bias between the two models is statistically significant at the 95% confidence level.  相似文献   

Transport in the Hudson estuary: A modeling study of estuarine circulation and tidal trapping     

Ferdi?L.?HellwegerEmail author  Alan?F.?Blumberg  Peter?Schlosser  David?T.?Ho  Theodore?Caplow  Upmanu?Lall  Honghai?Li 《Estuaries and Coasts》2004,27(3):527-538

The effects of estuarine circulation and tidal trapping on transport in the Hudson estuary were investigated by a large-scale, high-resolution numerical model simulation of a tracer release. The modeled and measured longitudinal profiles of surface tracer concentrations (plumes) differ from the ideal Gaussian shape in two ways: on a large scale the plume is asymmetric with the downstream end stretching out farther, and small-scale (1–2 km) peaks are present at the upstream and downstream ends of the plume. A number of diagnostic model simulations (e.g., remove freshwater flow) were performed to understand the processes responsible for these features. These simulations show that the large-scale asymmetry is related to salinity. The salt causes an estuarine circulation that decreases vertical mixing (vertical density gradient), increases longitudinal dispersion (increased vertical and lateral gradients in longitudinal velocities), and increases net downstream velocities in the surface layer. Since salinity intrusion is confined to the downstream end of the tracer plume, only that part of the plume is effected by those processes, which leads to the largescale asymmetry. The small-scale peaks are due to tidal trapping. Small embayments along the estuary trap water and tracer as the plume passes by in the main channel. When the plume in the main channel has passed, the tracer is released back to the main channel, causing a secondary peak in the longitudinal profile.  相似文献   

Geological and morphological study of the Jiufengershan landslide triggered by the Chi-Chi Taiwan earthquake   总被引：2，自引：4，他引：2  

Kuo-Jen Chang  Alfredo Taboada  Yu-Chang Chan 《Geomorphology》2005,71(3-4):293-309

The Jiufengershan rock and soil avalanche is one of the largest landslides triggered by the Chi-Chi earthquake Taiwan 1999. The landslide destabilized the western limb of the Taanshan syncline along a weak stratigraphic layer. It involved a flatiron remnant, which was almost entirely mobilized during the earthquake. The avalanche was slowed down by NS trending ridges located downstream along the Jiutsaihu creek. The landslide affected a 60 m thick and 1.5 km long sedimentary pile composed of shales and sandstones, which dip 22°SE toward a transverse valley. The triggering mechanism and the sliding process were analyzed by means of geological and morphological data from aerial photographs and observed in the field. A high-resolution airborne Light Detection and Ranging (LiDAR) image taken 2.5 years after the landslide allows the identification of morphological structures along the sliding surface and the landslide accumulation. The sliding surface shows several deformation structures such as fault scarps and folds. These structures are interpreted in terms of basal shear stresses created during the avalanche. Three major joint sets were identified at the sliding surface. The isopach map of the landslide was calculated from the comparison between elevation models before and after the earthquake. The coseismic volume of mobilized material and landslide deposit data are 42 × 10⁶ m³ and 50 × 10⁶ m³, respectively. The geometry of the landslide accumulation in the field has an irregular star shape. The morphology of the deposit area shows a sequence of smooth reliefs and depressions that contrast with the neighboring ridges.  相似文献   

Synrift stratigraphic geometry in a transfer zone coarse-grained delta complex, Miocene Pohang Basin, SE Korea   总被引：2，自引：0，他引：2  

Young Kwan Sohn  Moon Son† 《Sedimentology》2004,51(6):1387-1408

The Gojusan fan delta is a coarse‐grained delta complex on the western margin of the Miocene Pohang Basin, SE Korea. The deposits consist of five facies associations (FA): alluvial‐fan conglomerates (FA I), shallow‐marine mouth‐bar sandstones (FA II), fluvial and mouth‐bar conglomerates (FA III), Gilbert‐type foreset conglomerates (FA IV) and hemipelagic mudstones (FA V). Different facies associations characterize the northern, central and southern parts of the delta complex. To the north, FA IV is laterally juxtaposed with FA I or the basement, with scarp‐derived breccias along the contact. Centrally, and to the south, FA I is laterally juxtaposed with FA II, with an abrupt facies change and local inliers of basement rocks along the contact. Early alluvial fan and mouth‐bar deposits are overlain by the topset (FA III) and truncated by the foreset (FA IV) of a Gilbert‐type delta in the central part of the fan delta complex, whereas FA II passes transitionally upward into FA III in the south, with the latter extending basinward into a gently inclined shoal water delta front. Gilbert‐type and shoal‐water geometries are therefore developed in the same delta complex. The composite delta geometry is interpreted as reflecting (1) its development near an extensional transfer zone where the hangingwall relief was variable over short distances along strike, and (2) the operation of intrabasinal faults. This interpretation contrasts with previous studies that viewed the delta complex as having formed along a pull‐apart basin margin.  相似文献   

遥感变化检测技术发展综述   总被引：32，自引：2，他引：32  

马建文  田国良  王长耀  燕守勋 《地球科学进展》2004,19(2):192-196

卫星遥感的复轨能力，稳定一致的传感器参数和系列运行计划，连续记录了地表的显著变化信息。对遥感观测到的变化信息，还需要区分是地表物理生物要素变化引起的变化，还是辐射传输路径上其它干扰因素造成的变化信息，需要从各种变化信息组分中区分目标变化信息。因此，遥感变化检测是遥感信息科学、地球系统科学、统计学和计算机技术等学科技术交叉后新的增长点，代表了当前遥感数据处理技术发展方向。为了促进遥感变化检测技术在我国的发展，收集阅读了近几年国外主要遥感刊物发表的论文、专著，综合了我国遥感变化检测技术发展现状以及大量的网络资料。  相似文献   

天然洞围岩稳定性评价   总被引：2，自引：1，他引：2  

常士骠 《岩土工程技术》2004,18(2):72-73,77

天然洞体不稳定是绝对的 ,稳定是相对的。天然洞体围岩的顶板、底板、侧面三者的稳定 ,顶板的稳定最重要。顶板的稳定性 ,与天然洞体的形成原因 ,岩面的成层条件、断面形状、裂隙情况 ,漏水情况 ,天然洞体形成和稳定的时间 ,山体的地质构造条件等有关。  相似文献