影响粘土静止侧压力的一些问题

本文讨论了土的物理属性，应力历史，结构特性、土骨架的流变性质以及测量时采用的应力－应变路径等对静止侧压力的影响，最后，说明了对不同土实在实施Ｋ０值的测定时应注意的问题及对测试设备的要求。     

Evaluation of rainfall–runoff model performance under non-stationary hydroclimatic conditions

ABSTRACT

Understanding of rainfall–runoff model performance under non-stationary hydroclimatic conditions is limited. This study compared lumped (IHACRES), semi-distributed (HEC-HMS) and fully-distributed (SWATgrid) hydrological models to determine which most realistically simulates runoff in catchments where non-stationarity in rainfall–runoff relationships exists. The models were calibrated and validated under different hydroclimatic conditions (Average, Wet and Dry) for two heterogeneous catchments in southeast Australia (SEA). SWATgrid realistically simulates runoff in the smaller catchment under most hydroclimatic conditions but fails when the model is calibrated in Dry conditions and validated in Wet. All three models perform poorly in the larger catchment irrespective of hydroclimatic conditions. This highlights the need for more research aimed at improving the ability of hydrological models to realistically incorporate the physical processes causing non-stationarity in rainfall–runoff relationships. Although the study is focussed on SEA, the insights gained are useful for all regions which experience large hydroclimatic variability and multi-year/decadal droughts.     

Laboratory examination of linearity in rainfall–runoff relationships

ABSTRACT

Certain rainfall–runoff models, e.g. the unit hydrograph, assume linear relationships between the variables. These are proportionality of runoff discharges to (net) rainfall depth and linear summations of discharges resulting from (net) rainfalls during different time intervals or over different sectors of a watershed. This study examines the validity of these assumptions by use of an extensive two-dimensional laboratory experimentation. The results indicate that proportionality would be found under high rainfall intensity through a long duration. Spatial summations would more likely yield correct discharges in cases where rainfall duration is equal to, or is longer than, the time of concentration. Temporal summations may yield correct discharges when rainfall duration is longer than one half of the time of concentration. Here, the time of concentration is determined at the beginning of gradual approach of the discharge towards the equilibrium state.     

Three-dimensional velocity images in Yunnan and its neighboring district

Using the techniques of seismic tomography three-dimensional velocity images at crust and upper mantle in Yunnan province and its adjacent region have been successfully reconstructed. The results of image are: (1) The image of the velocity in the upper crust is closely related to the well-known geological structure of the surface, the Kangdian earth axis is a distinct high velocity area, and a high velocity rock stratum, which appoaching the surface of the earth, has been formed. (2) There is a low-velocity layer between 26°–31°N and 100°–104°E in deep crust, the depth of Moho discontinuity in Sichuan bass in is less than 50 km. (3) The results of seismological tomography not only reveal the lateral heterogeneity in the researched region, but also find approximately the strike of Honghe fault from the image at bottom of crust, and the velocity in both side of the fault are different obviously. (4) There is a low-velocity column within 25 km to 110 km in Tengchong region, which may be occured by upward moving of the basalt in the mantle. (5) In studied area, the thickness of the crust in west part is thicker than in southeast part. (6) From the image at bottom of the crust we can find that earthquakes with magnitude greater than 5 occurred in big velocity gradient zones, especially in transition zone between high and low velocity. There are a few earthquake in the low-velocity area. (7) We can see from Figure 6 that there still clearly exists lateral heterogeneity at 450 depth. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 61–67, 1993.     

中大流域水沙耦合模拟物理概念模型

根据黄河中游、北方干旱地区流域的超渗产流水文特征和冬季积雪的累积及融化机制,提出了中大流域水流模拟模型,结合黄土地区小流域坡面产沙、汇沙和沟蚀产沙、汇沙计算公式,构成了中大流域水沙耦合模拟物理概念模型。该模型较好地处理了北方干旱地区中大流域用下渗曲线计算地面径流中存在的观测资料缺乏、数据处理量太大两大难题;考虑了大流域气候、下垫面因素空间的不均匀性和雨洪径流产沙与融雪径流产沙间的差异。经流域实测资料的模拟检验表明,模型结构较合理,模拟结果较好。     

自组织特征映射神经网络及其在彩色地图自动分层中的应用

地图数据分层是地图识别系统的一个重要组成部分。由于传统的基于Ｂａｙｅｓ准则识别方法要求已知概率分布密度，当实际概率分布与假设条件存在差异时，无法取得满意的识别效果。神经网络方法可以克服这些缺点。本文利用Ｋｏｈｏｎｅｎ提出的自组织特征映射网络的学习、识别能力，实现了对彩色地图扫描数据的自动分层。     

石油地震勘探中的薄层解释研究方法综述

概述了当前石油地震勘探中薄层研究的下列主要方面:关于薄层的标定,主要方法有垂直地震剖面法、理论合成记录法、平均速度法和多档滤波法;薄层厚度求取的主要方法有:相对振幅—时间厚度法、间接振幅法、反射波特征点法、积分振幅与视时差乘积法、窄带滤波法以及标定曲线法和振幅谱能量等方法;薄储集体圈定及横向预测,主要着重于由界面型剖面向岩层型剖面转换方法的研究,如:地震岩性模拟技术、合成声波测井等方法。     

Magma mixing model for the genesis of middle crust in the Izu–Bonin–Mariana arc: evidence from plutonic rocks in the Mineoka-Setogawa ophiolitic mélange,central Japan

ABSTRACT

A Paleogene accretionary complex, the Mineoka–Setogawa belt is distributed adjacent to the northern portion of the collision zone between Honshu and Izu–Bonin–Mariana (IBM) arcs in central Japan, comprising a mélange of ophiolitic fragments of various sizes. The Eocene-Oligocene plutonic rocks in this belt (gabbro, diorite, and tonalite) have been interpreted as fragments brought from the deep crust beneath the IBM arc through tectonic collisions. The geochemical characteristics of the gabbro and associated basaltic dike are similar to those of the Eocene IBM tholeiitic basalt; thus, the gabbro was likely formed via the crystallization of the Eocene tholeiitic basaltic magmas, which was produced by the partial meltings of a depleted mantle wedge. A comparison with experimental results and geochemical modeling indicates that the tonalite was generated by 10–30% dehydration melting of the gabbro. Actually, Eocene–Oligocene felsic veins, which are coeval with the plutonic rocks, occur in the Mineoka–Setogawa gabbro. Plagioclase crystals in the diorite comprise Ca-rich and -poor parts in a single crystal. Their compositional characteristics are consistent with those of plagioclase in the gabbro and tonalite, respectively. The textures and chemical composition of plagioclase indicate that the diorite was formed by the mixing between mafic and silicic magmas. The whole-rock composition of the diorite also indicates the evidence for the mixing between basaltic magmas which were fractionated to variable degrees and homogeneous silicic magma. The mixing model proposed from the first direct observations of the IBM middle crust exposed on the Mineoka–Setogawa belt is applied to the genesis of the Eocene to present intermediate rocks in the IBM arc. If the continental crust were created at intra-oceanic arc settings such as the IBM arc, the magma mixing model would be one of the most likely mechanisms for the genesis of the continental crust.     

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

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.