峨眉山溢流玄武岩省高钛玄武岩的两种不同地幔源特征

为探讨和揭示峨眉山高钛玄武岩的幔源特征,以二滩高钛玄武岩为研究对象进行了主要元素、微量元素和Sr-Nd-Pb同位素的系统研究。研究表明:二滩高钛玄武岩可分为A和B两组玄武岩;两组岩石间的微量元素(Rb﹑K﹑Ba﹑Th﹑Nb和Ta)富集程度和微量元素比值(Ba/Nb﹑Ba/Th﹑Zr/Nb﹑Th/La、Zr/Hf)以及同位素比值(⁸⁷Sr/⁸⁶Sr、²⁰⁸Pb^*/206Pb^*)均存在较为明显的差异。造成这种差异的原因不是岩浆过程(结晶分异、地壳混染、部分熔融)的不同,而是A组和B组具有不同的地幔源。A组具有EM II特征,可能为富含辉石岩的交代地幔部分熔融所形成;B组则具有EM I和C组分的混合特征,可能为交代谱系较宽的地幔物质熔融所形成。     

Study On Development And Application Of A Regional Pbl Numerical Model

A regional scale (a few km to a few hundred km, minutes to days)planetary boundary layer (PBL) numerical model (RPBLM) has been successfully developed to simulateprecisely the boundary-layer three-dimensional characteristics. The RPBLM model with a high-resolutionnon-hydrostatic E - turbulence closure scheme has been applied to diagnose and prognosticate the PBL characteristicsover a complex underlying surface in the Hong Kong area of 60 km × 48 km. It is shown that the RPBLMmodel can be used to simulate the PBL characteristics including wind, temperature, water vapour andturbulence over such a complex underlying surface and that the simulated result is reasonably in agreementwith observations.     

济阳坳陷古近系成岩作用及其对储层质量的影响?

大量的储层分析化验资料研究表明，济阳坳陷古近系砂岩储层经历了压实、胶结等多种成岩作用。压实作用以机械压实为主，压溶作用较少。胶结作用主要有十分普遍的石英次生加大胶结、碳酸盐胶结、粘土矿物胶结。碳酸盐胶结物有早、晚两期，早期泥晶方解石主要分布在浅层，连晶方解石充填的深度分布范围大，中深部最为发育。溶蚀作用主要有碳酸盐胶结物、长石颗粒和少量岩屑溶蚀。储层孔隙经历了由原生到次生的演化过程，在成岩演化过程中，长石的溶蚀作用、碳酸盐矿物的沉淀与溶解作用是影响孔隙大小的关键因素，早期方解石的胶结有利于后期次生孔隙的发育。不同凹陷次生孔隙发育的深度不同。在济阳坳陷西部的惠民凹陷次生孔隙主要发育于1500-2400m深度，向东至东营凹陷则主要发育于1650-2450m，再向东到沾化凹陷为2300-3500m，车镇凹陷为2200-2700m。从西向东、由南向北次生孔隙的发育深度逐步增大是受盆地沉积沉降中心的迁移规律控制的。     

京北云蒙山变质核杂岩南东侧剥离断层带的构造热演化

以云蒙山变质核杂岩东侧的河防口低角度正断层为研究对象,通过矿物(黑云母)的变形特征和形成环境分析,获得了该断层带上的构造热演化环境:温度为780～860℃,压力约为7.3×108～8.6×108Pa.提出云蒙山变质核杂岩的成因机制是,在区域伸展背景下,处于半固结状态的云蒙山花岗岩在东南侧卷入河防口-水峪伸展型韧性剪切带,使花岗岩发生中高温条件的韧性变形;之后,该韧性剪切带在隆升过程中不断向浅层次过渡,形成了一些浅层次的脆性伸展变形构造.     

Main Factors Affecting the Distribution of the Macroscopic Destruction Field of Earthquake

It is proposed that some possible macroseismic epicenters can be determined quickly from the relationship that the microseismic epicenters located by instruments bear with faults.Based on these so-called macroseismic epicenters,we can make fast seismic hazard estimation after a shock by use of the empirical distribution model of seismic intensity.In comparison with the method that uses the microseismic epicenters directly,this approach can increase the preccision of fast seismic hazard estimation.Statistical analysis of 133 main earthquakes in China was made.The result shows that the deviation distance between the microseismic epicenter and macroseismic epicenter falls within the range of 35km for 88% earthquakes of the total and within the range of 35to 75km for the remaining ones.Then,we can take the area that has the microseismic epicenter as its center and is 35km in radius as the area for emphatic analysis,and take the area within 75km around the microseismic epicenter as the area for general analysis.The relation between the 66 earthquake cases on the N-S Seismic Belt in China and the spatial distribution characteristics of faults and the results of focal mechanism solution were analyzed in detail.We know from the analysis that the error of instrumental epicenter determination is not the only factor that gives effects to the deviation of the macroseismic epicenter.In addiditon to it,the fault size,fault distribution,fault activity,fault intersection types,earthquake magnitude,etc,are also main affecting factors.By sorting out ,processing and analyzing these affecting factors,the principle and procedures for quickly determining the possible position of the macroseismic epicenter were set up.Taking these as a basis and establishing a nationwide database of faults that contains relevant factors,it is possible to apply this method in practical fast estimation of seismic hazard.     

宁夏旅游经济与生态环境耦合协调过程与格局

实现区域旅游经济与生态环境协调发展是旅游业发展的重要目标,也是实现沙漠旅游主导型省区旅游产业可持续发展的关键。构建沙漠旅游主导型省区旅游经济与生态环境耦合协调评价指标体系,综合运用耦合协调度模型、剪刀差模型以及ArcGIS空间可视化表达方法对2009—2018年宁夏旅游经济与生态环境耦合协调过程与格局进行了分析研究。结果表明：宁夏旅游经济与生态环境发展水平呈逐年增长态势,且各市发展程度差异显著;耦合协调度指数由2009年的0.3121上升至2018年的0.5655,旅游经济与生态环境的关系不断改善,趋向于协调发展,耦合协调程度由低水平失调的旅游经济滞后型发展为高水平协调的生态环境滞后型;宁夏旅游经济与生态环境耦合协调空间格局变化明显,且差异显著;剪刀差整体演化速率较为稳定,波动趋势极为平缓,表明两系统演化速率差异基本保持稳定状态;而耦合度夹角在45°—90°波动变化,表明两系统正处于协调发展阶段。     

SHRIMP U-Pb zircon geochronology and Hf isotope analyses of Middle Permian–early triassic intrusions in southern Manzhouli area,Northeast China: implications for the subduction of Mongol-Okhotsk plate beneath the Erguna massif

ABSTRACT

The results of SHRIMP U-Pb ages and in situ Hf isotope of zircons from three granites in the southern Manzhouli region of northeast China, provide new data to understand the subduction process of Mongol-Okhotsk Plate beneath the Erguna massif. SHRIMP U-Pb zircon geochronology results yield an age of 265.5 Ma (middle Permian) for fine-grained monzogranite. Rocks from the Early–Middle Triassic are mainly granodiorite (247.4 ± 4.6 and 249.3 ± 4.9 Ma), the granites are with SiO₂ = 60.0–77.4 wt.%, Al₂O₃ = 12.3–16.8wt.% and Na₂O/K₂O = 0.7–1.9. Chemically, they are metaluminous to peraluminous and belong to the high-K calc-alkaline series. Enrichments in the large ion lithophile elements (e.g., Rb, Ba, and K) and depletions in the high field strength elements (e.g., Nb, Ta, and Ti) are typical for these rock types. The monzogranite (~265 Ma) and granodiorite (~247 Ma) contain zircons with εHf(t) values of 6.3–8.5 and 5.1–7.9, yielding T_DM2 model ages of 888–752 and 958–774 Ma, respectively. These geochemical and zircon Hf isotopic data indicate that primary magmas for Middle Permian–Early Triassic granites crystallized from primary magmas generated by Neoproterozoic crustal materials, formed in an active continental margin setting. The andesite of the Gegenaobao formation is similar with the Izu–Bonin–Mariana arc, relating to subduction initiation. Based on the characteristics of exposed rocks and zircon U-Pb ages of andesite and granitoid rocks in the study area, we conclude the onset subduction of Mongol-Okhotsk Plate beneath the Erguna massif may occur at early-middle Permian.     

Spatio-temporal evolution of drought and flood disaster chains in Baoji area from 1368 to 1911

Based on the collation and statistical analysis of flood and drought information in Baoji area from 1368 to 1911, and in the context of climate change, we investigated the spatio-temporal evolution characteristics of drought and flood disaster chains in this area during the Ming and Qing dynasties using the methods of moving average, cumulative anomaly and wavelet analysis. The results are as follows: (1) We found a total of 297 drought and flood events from 1368 to 1911 in Baoji. Among these events, droughts and floods occurred separately 191 and 106 times, which accounted for 64.31% and 35.69% of the total events, respectively. (2) We observed distinct characteristics of flood and drought events in Baoji in different phases. The climate was relatively dry from 1368 to 1644. A fluctuant climate phase with both floods and droughts occurred from 1645 to 1804. The climate was relatively wet from 1805 to 1911. Moreover, we observed a pattern of alternating dry and wet periods from 1368 to 1911. In addition, 3 oscillation periods of drought and flood events occurred around 70 a, 110 a and 170 a, which corresponded to sunspot cycles. (3) We also observed an obvious spatial difference in drought and flood events in Baoji. The northern and eastern parts of Weihe River basin were regions with both frequent droughts and floods. (4) The sequential appearance of drought and flood disaster chains in Baoji from 1368 to 1911 was in response to global climate change. Since the 1760s, global climatic deterioration has frequently led to extreme drought and flood events.     

Optimal spatial allocation of water resources based on Pareto ant colony algorithm

The spatial allocation of water resources is optimised using the multi-objective functions and multi-constrained conditions of the Pareto ant colony algorithm (PACA). The objective function is the highest benefit to the economy, society and the environment, while the constraints include water supply, demand and quality. The PACA is improved by limiting local pheromone scope and dynamically updating global pheromone levels. Since both strategies guide the ant towards borders of high-pheromone concentration, the new approach enhances the global search capability and convergence speed. Programming, database management and interface tools are then integrated into geographic information systems (GIS) software. The study area is located in Zhenping County, Henan Province, China, and water resource data are obtained using remote sensing (RS) and GIS technology. The improved PACA is solved in the GIS environment. Optimal spatial allocation schemes are obtained for surface, ground and transferred water and the model yields optimal spatial benefit schemes of water resources, embracing economic, social and ecological benefits. The results of improved PACA are superior to those of other intelligent optimisation algorithms, including the ant colony algorithm, multi-objective genetic algorithm and back-propagation artificial neural network. Therefore, the integration of RS, GIS and PACA can effectively optimise the large-scale, multi-objective allocation of water resources. The model also enhances the global search capability, convergence speed and result precision, and can potentially solve other optimal spatial problems with multi-objective functions.