赛什塘矿区侵入岩的地球化学特征及构造环境分析

青海赛什塘地区岩体分布普遍,是多期次侵入的结果。岩体主要以高钾、过铝质、同属钙碱性系列为特征,具有较低含量的稀土元素丰度值,轻稀土富集,重稀土亏损,铕异常不明显,属I型花岗岩。岩体有Y/Tb值高低不同的两个源区,一是由柴达木地块东南缘岩石圈地幔构成的地幔楔形体,另一个是受其它物源污染的岩浆,是岛弧形成过程中不同阶段的产物。矿区内发现埃达克岩,岩体富含成矿元素,为成矿提供了物质条件。     

粘土中圆形隧道上限解的研究

根据极限分析上限理论,基于Davis等人提出的隧道垮落模型,提出了剪切区参数α等于1时的新的隧道垮落模型。由不可压缩性条件和速度连续性条件求出了剪切区速度和间断线表达式,计算了该模型间断线上能量耗损、剪切区能量耗损和总外力所做的功。利用功能原理,求出了稳定率的表达式,并计算了相应的稳定率。从求解结果来看,所得上限解小于Davis等人的结果,因而该上限解将更接近真实解。从与实验结果比较来看,该上限解位于实验值附近,能与实验结果比较好地吻合,从而说明该模型更加接近真实隧道垮落情形。该上限解可为隧道支护提供理论依据。     

A catastrophic rockslide-debris flow in Wulong, Chongqing, China in 2009: background, characterization, and causes

On June 5, 2009, a catastrophic rockslide-debris flow occurred at the crest of the Jiweishan Mountain in Wulong, Chongqing, China. Approximately five million cubic meters of limestone blocks slid along a weak interlayer of bituminous and carbonaceous shale. The source mass descended from the upper part of the slope rapidly, crossing a 200-m wide and 50-m deep creek in front of it. Blocked by the opposite steep creek wall, the sliding mass changed its direction and traveled a further 2.2 km along the creek in debris-flow mode, finally forming a large accumulation zone with an average depth of 30 m. This is one of the most catastrophic rockslide events in recent years in China. It buried 12 houses and the entrance of an iron mining tunnel where some 27 miners were working inside. Ten people died, 64 missing, and eight wounded. Immediately after this disaster happened, the government organized an expert team to assist the rescue work. As one of the geological experts, the author did a lot of field investigations and collected first-hand information. Multi-methods including the remote sensing, 3D laser scanning, geophysical exploration, and numerical modeling were used for analyzing the characteristics and the triggering mechanism of the Wulong rockslide. The preliminary investigation results reveal that this rockslide with poor geological conditions was mainly induced by the gravitation and the karst effect and also affected by the previous mining activities. The research in this paper is meaningful and useful for further research on such kind of rockslides that are geologically similar to the Wulong rockslide.     

藏南亚东地区片麻状含石榴子石黑云花岗闪长岩LA-ICP-MS锆石U-Pb测年及其地质意义

亚东岩组是高喜马拉雅地区重要的前寒武纪变质地层之一。利用LA-ICP-MS锆石U-Pb测年技术对侵入亚东岩组的片麻状含石榴子石黑云花岗闪长岩进行了测年,获得岩浆结晶年龄为(499.2±3.9)Ma(中寒武世),提供了泛非构造-岩浆事件的记录。岩石地球化学分析表明,黑云花岗闪长岩SiO2含量为68.04%～68.92%,在(K2O+Na2O)-SiO2图解上样品点落入亚碱性系列的花岗闪长岩区,A/CNK指数均大于1.1,在Shand指数图解上落入过铝质系列区。稀土元素配分模式属轻稀土元素富集的右倾曲线,出现弱Eu负异常(δEu=0.62～0.79);微量元素表现出Ba、Nb、Ta、Sr亏损和Rb、Th、U相对富集的特征。通过Rb-(Y+Nb)和Rb-Hf-Ta图解判别,认为亚东地区片麻状含石榴子石黑云花岗闪长岩形成于后碰撞构造阶段。     

Parameters optimization based on the combination of localization and auto-calibration of SWAT model in a small watershed in Chinese Loess Plateau

This study simulated the watershed flow and sediment responses based on calibration of the SWAT model in the semi-arid Chinese Loess Plateau (LP) where soil erosion intensively occurs. After the model’s initiation and manual modification, a 7-year inconsecutively observed flow and sediment data from 1984 to 1990 was used to analyze the model’s application in the selected watershed called AJW in the Chinese LP region. The model procedure included sensitivity analysis, parameter calibration and model validation. The best parameter set was finally determined based on the combination of parameter localization and auto-calibration. Then the model was assessed for its accuracy based on the NSE estimation, resulting in 0.77 and 0.67 for calibration and 0.46 and 0.32 for validation on simulations for flow and sediment, respectively, which is a moderately satisfactory accuracy among the applications of the SWAT model. Annual watershed assessment on flow and sediment with the calibrated SWAT model resulted in a multiyear averaged annual runoff coefficient of about 2.7% and an erosion modulus of 797 t/(km²·a⁻¹) in the AJW, indicating a beneficial consequence from the implementation of the historical soil and water conservations.     

地震弯线技术在地形复杂地区煤田勘探中的应用

环县地区属于典型的巨厚黄土覆盖区,山大沟深,地形复杂。激发和接收条件极差,若采用常规直测线设计,野外施工非常困难,且地震勘探效果较差。面对山区、丘陵沟壑区的复杂地震地形条件,在精确计算接收点和激发点坐标的基础上,通过试验确定了弯曲测线折线转角大小、面元大小、叠加次数等主要参数,并利用共反射面元叠加原理进行资料处理,取得了良好的地质效果。     

Analysis of Baishuihe landslide influenced by the effects of reservoir water and rainfall

Since the impoundment of the Three Gorges Reservoir in June 2003, a number of new landslides have occurred and existing landslides have been made worse. The 1,260 × 10⁴ m³ Baishuihe landslide, located at 56 km west of the Three Gorges Dam, began to deform more noticeably after the first impoundment in early July 2003. The sliding of the two blocks comprising the landslide, one an active block and the other a relatively stable block, became apparent after approximately 5 years of monitoring. Field recordings show that the landslide displacement is affected by the combined effects of the rainfall and water level in the reservoir. These effects have been investigated in the present paper, including the deformation characteristics (movement pattern, direction, displacement and velocity) earmarking the temporal evolution of the active block. Based on a practical creep model of a large rock slide, alert velocity thresholds for pre-alert, alert and emergency phases have been computed corresponding to the imminence of failure. The alert velocity thresholds are being proposed to be included as a part of an early-warning system of an emergency plan drawn up to minimize the adverse impact in the event of landslide failure. The emergency plan is intended to be implemented as a risk management tool by the relevant authorities of the Three Gorges Reservoir in the near future.     

The impact of Greenland melt on local sea levels: a partially coupled analysis of dynamic and static equilibrium effects in idealized water-hosing experiments

Local sea level can deviate from mean global sea level because of both dynamic sea level (DSL) effects, resulting from oceanic and atmospheric circulation and temperature and salinity distributions, and changes in the static equilibrium (SE) sea level configuration, produced by the gravitational, elastic, and rotational effects of mass redistribution. Both effects will contribute to future sea level change. To compare their magnitude, we simulated the effects of Greenland Ice Sheet (GIS) melt by conducting idealized North Atlantic “water-hosing” experiments in a climate model unidirectionally coupled to a SE sea level model. At current rates of GIS melt, we find that geographic SE patterns should be challenging but possible to detect above dynamic variability. At higher melt rates, we find that DSL trends are strongest in the western North Atlantic, while SE effects will dominate in most of the ocean when melt exceeds ~20 cm equivalent sea level.     

TZ Lyrae： an Algol-type Eclipsing Binary with Mass Transfer

We present a detailed investigation of the Algol-type binary TZ Lyrae, based on 55 light minimum timings spanning 90 years. It is found that the orbital period shows a long-term increase with a cyclic variation superimposed. The rate of the secular increase is dP/dt = 7.18 × 10?8d yr?1, indicating that a mass transfer from the less massive component to the more massive one at a rate of dm = 2.21 × 10-8M⊙yr-1. The cyclic component, with a period of P3 = 45.5 yr and an amplitude of A = 0d.0040, may be interpreted as either the light-time effect in the presence of a third body or magnetic activity cycles in the components. Using the latest version Wilson-Devinney code, a revised photometric solution was deduced from B and V observations. The results show that TZ Lyr is an Algol-type eclipsing binary with a mass ratio of q = 0.297(±0.003). The semidetached configuration with a lobe-filling secondary suggests a mass transfer from the secondary to the primary, which is in agreement with the long-term period increase of the binary system.     

Numerical study of two‐phase fluid distributions in fractured porous media

Two‐phase fluid distributions in fractured porous media were studied using a single‐component multiphase (SCMP) lattice Boltzmann method (LBM), which was selected among three commonly used numerical approaches through a comparison against the available results of micro X‐ray computed tomography. The influence of the initial configuration and the periodic boundary conditions in the SCMP LBM for the fluid distribution analysis were investigated as well. It was revealed that regular porous media are sensitive to the initial distribution, whereas irregular porous media are insensitive. Moreover, to eliminate the influence of boundaries, the model's buffer size of an SCMP LBM simulation was suggested to be taken as approximately 12.5 times the average particle size. Then, the two‐phase fluid distribution of a porous medium was numerically studied using the SCMP LBM. Both detailed distribution patterns and macroscopic morphology parameters were reasonably well captured. Finally, the two‐phase fluid distributions in a fractured porous media were investigated. The influence of the degree of saturation, fracture length, and fracture width on the fluid distributions and migration was explored. Copyright © 2015 John Wiley & Sons, Ltd.