Differences of granitic weathering at the northern and southern feet of Dabie Mountains,Central China: Implication for tectonic and climatic environments

Previous studies of weathering generally started with geochemistry[1—8] and mineralogy[9—12], and have been focused on chemical weathering rates[1—3], removability-enrichment of elements[3—6] during chemical weathering, and the age of weathering profi…     

Zircon geochronology and geochemistry of mafic xenoliths from Liaoning kimberlites:Track the early evolution of the lower crust,North China Craton

Since the formation of the primal nucleus at 3.8Ga[1], the North China had underwent the multi-cycle geologic processes such as arc accretion[2—4] andrift[5—7], and finally accomplished the craton[8] aroundat 1.8 Ga[2,3,9]. Paleozoic Fuxian kimberlites (LiaoningProvince) contain not only abundant peridotitic butalso mafic xenoliths. The investigation on peridotiticxenoliths indicted that the North China Craton hadcold and thick lithospheric root in the middle Ordovi-cian. The deep part o…     

用双扭方法研究岩石的断裂韧性

本实验用双扭技术测量了济南辉长岩的断裂韧性.在干、湿及垂直向位移恒定的条件下,用双扭松弛方法测定裂纹的扩展速度 V.得到了与 Atkinson [1]类似的结果.济南辉长岩的断裂韧性为:KIC=2.810.03MNm-3/2.本文提出了 Spetzler[2] 和 Atkinson 关于在湿条件下亚临界裂纹扩展机制的不同看法.由声发射的实验结果看出,声发射率与应力强度因子的关系呈现了与 K1——V 曲线类似的趋势.      

山西地震带震群与地震序列活动特征

本文利用文献[1]、[2]和1)所采用的方法,对邢台地震后在山西地震带发生的震群和地震序列的U值、h值和k值进行了计算。结果表明,在山西地震带中,如果出现U≥0.6、K≥0.8或h>1的震群活动,在大华北东部都有中强地震发生。本文还讨论了山西震群与地震序列活动和大华北中强地震的关系。认为在1966—1976年大华北地震活动幕里,山西地震带的地震活动受其东部河北平原地震带的影响和控制。     

Synchrotron radiation X-ray diffraction in situ study of fine-grained minerals in shock veins of Suizhou meteorite

The Suizhou meteorite is an L6chondrite,which fell on April15,1986in Dayanpo,12.5km in the southeast of Suizhou City,Hubei Province,China[1].This meteorite is shock-metamorphosed to shock stage3—4[2].A few thin shock melt veins of0.02—0.09mm in width were observed in this chondrite[1,2].Similar to many other L6chondrites[3—5],the Suizhou shock veins contain two assemblages of high-pressure minerals[2,6—8]:(i)the“coarse-grained”assemblage of ringwoodite+majorite+NaAlSi3O8-hollandite…     

Apatite-fission-track geochronology and its tectonic correlation in the Dabieshan orogen,central China

The thermochronology based on a combination ofradiometric age and closure temperature (Tc) is widelyaccepted as a sensitive method to provide constraintson tectonic evolution of the orogen, and numerousadvances as a result of thermochronological applica-tions have been made recently in the Dabieshan oro-gen[1—5]. Zircon U/Pb, hornblende Ar/Ar and biotiteAr/Ar ages with Tc= 800—300℃[6] will yield a wealthof information on the cooling and exhumation of rockscrossing crustal levels of 30—1…     

Geochemistry of ophiolite cherts from the Qinling orogenic belt and implications for their tectonic settings

Since the 1980s, one of the important progresses in the study of the Qinling orogenic belt is marked by findings of numerous ophiolite zones[1—4]. On the basis of the former orogenic models of the Paleozoic colli-sional orogeny[1,5,6] and the Mesozoic collision[7—9], another orogenic evolution model from the Paleozoic subduction-collision along the Shangdan suture to the Mesozoic final collision orogeny along the Mianle suture[3,10], including the relicts of the Jining orogeny, has been pr…     

Wilson—θ法中非线性拐点的精确处理方法

本文在文献[1]基础上,进一步分析了用Wilson—θ法求解具有折线型非线性特性的结构动力反应分析中拐点处理的精确方法,并详细讨论了变步长Δt’的取值问题。     

初探地震活动的时间分维特征

关于分维数的基本概念及测定方法见文献[1]、[2]。     

一种消除地电阻率观测中线间漏电的新方法

本文在文献[1]、[2]的基础上,介绍了一种消除地电阻率观测中线间漏电的新方法。该法通过在安徽省灵璧地电台的实验,证明它是简单易行、投资低、收效大,具有推广价值。并为今后地电阻率观测提出了一种新的外线设计方案。 新方法的理论及实验基础 文献[1]、[2]详细讨论了地电阻率观测中线路漏电问题,系统地介绍了在安徽省屯溪地电台所做的漏电实验。其中获得的主要结论是:(1)用理论公式定量地算出供电线对     

京津地区小震(1987.4—10)震源参数

利用时间域中计算小地震震源参数的方法,求出了京津地区1987年4月至1987年11月间M_L> 1.8级20个地震的震源参数,如表1所示。表1中T,为由地震图中测出的(?)波初动半周期,u_(αm)为(?)波初动振幅,α为求出的震源半径,M_0为地震矩,Δ_σ为应力降。震源半径α是利用参考文献[1]中的T_r—α/v关系曲线,假定Q=400,破裂速度v=2.75公里/秒求出的。由[1]中图2的α/v—u′_(αm)关     

华北地区地磁场长期变化的地区差异

本文根据文献[1]给出的泰勒二次多项式曲面拟合方法,利用1980—1987年23个地磁台地磁总场F和Z分量实测资料,从年变率地区性差异方面进行了分析,从另一个侧面描述了地磁场长期变化的时空特征,达到了拟合与预测的目的。同时克服了文献[1]中外空干扰对年变率产生的系统拟合偏差的影响。此资料便于用差值法进行长期变改正,具有实用价值。     

Modeling the East Asian climate during the last glacial maximum

Climatologists have been paying much attention to the global and regional climatic charac-teristics during the LGM. A lot of paleodata were obtained in East Asia during the LGM[1—5] and laid the firm foundation of reconstructing East Asian paleoclimate t…     

Estimation on dynamic release of phosphorus from wind-induced suspended particulate matter in Lake Taihu

The internal source, especially resuspension process of the sediments in lakes and its environ- mental effect has been paid shining attention in the West as well as in China[1—6] although the influence of external source is important to water environment[7]. S鴑dergaard et al. compared the releases of soluble reactive phosphorus (SRP) in the surface sediments of Lake Arres before and after disturbance and they found that disturbing can increase the release by 20—30 times[3]. Robarts and ot…     

答商榷作者的意见

文献[1]中把(8)式变形成文献[1]中(20)式,应用了“地球物理学报第11卷第二期中平面波产生的侧波一文中所采用的方法”。 文献[1]有:     

Geospatial-temporal analysis of land-use changes in the Yellow River Delta during the last 40 years

Research on land use/land cover changes (LUCC)has been the core project of the Global EnvironmentalChanges since the 1990s[1—6]. Scientists at home andabroad have been laying emphasis on integrationstudies on land-use change by “space and process”features[7—10] as researches on LUCC are in a greatdeal. It is of paramount important for us to studyLUCC at various spatial-temporal scales and build aquantitative assessment of land-use conversion by in-tegrated spatial-temporal features. …     

重正化群方法在地震预报中的应用

本文在文献[1]—[4]的基础上,用现代统计物理学观点以及重正化群方法研究了组合模式中应力积累单元的应力积累进入非线性阶段后,一维和二维震源体的破裂问题,得到了震源体破裂概率的临界值分别为0.2063和0.1707。应用二维震源体的破裂临界值,得到了孕震空区的围空地震的能量之和与参考能量的比值的临界值为0.1872,并用大华北地区1967年—1980年的10个孕震空区和1982年—1986年大华北地区所有起始震级为M_L=2.3的孕震空区进行了检验,结果是令人满意的。初步认为,临界值0.1872可以作为孕震空区危险性的判别指标。     

Early-Mid Ordovician brachiopod diversification in South China

Since the recognition of the Cambrian Evolutionary Fauna, Paleozoic Evolutionary Fauna and Modern Evolutionary Fauna[1—3], more and more paleontolo-gists have paid attention to the great Ordovician bio-diversification event which was critical to the forma-tion of the Paleozoic Evolutionary Fauna, and during which the marine organisms experienced one of the most profound evolutionary radiations of the Phan-erozoic[4]. Three biodiversity maxima have been rec-ognized on a global scale[5] wi…     

北京地区地壳Q值随深度的分布特征

地震波在介质中的衰减,是介质的重要特性之一,而Q值则是衡量衰减特性的主要物理参数,称之谓介质的品质因子。根据文献[1]提出的方法,用北京台网记到的近震直达P波资料,测定北京地区的大量Q值表明:Q值与P、S波到时差(t_s—t_p)有关;(t_s—t_P)大,测得的Q值也大;(t_s—t_P)小,测得的Q值也小。这种现象在朱传镇、李兴才     

应重点关注已知活断层

致编者——最近在《自然—地球科学》（Nature Geoscience）杂志上发表的一篇评论[1]（见本期第34页译文：＂地震区划图上未明确标注的地震危险＂——编者注）认为地震科学和危险性评估最优先考虑的应该是大陆内部大量的隐伏断裂的识别。