2020年10月15日地磁垂直强度极化异常与玛多M7.4地震

利用地磁垂直强度极化法对2020年1月至2021年5月期间中国大陆西部的磁通门磁力仪秒采样观测资料开展了5 ～100 s频段的极化分析.发现2020年10月15日出现一次异常,高值出现的地震台站集中在甘肃、青海、四川、重庆、广西等地,插值后的空间分布图中形成一个大范围高值异常区,从青海中部一直延伸至了广西北部.同时,对...     

基于GPS应变、地震应变率与震源应力场对帕米尔高原现今构造变形特征的分析

研究帕米尔高原的构造变形特征对于理解印度板块向北推挤过程中的应变分配方式以及应力转换模式具有重要的意义.本文利用区域GPS应变场、地震应变场与震源应力场分析帕米尔高原的构造形变特征.主要结论为:(1)该区域变形主要以NNW-SSE或近N-S向的挤压为主,在高原内部伴有明显的近ENE-WSW或E-W向拉张,应力方向在帕米尔高原与塔吉克盆地区域呈现逆时针旋转的趋势,而在塔里木盆地则显示几乎与帕米尔高原的一致的应力状态,这可能与两侧盆地块体的强度差异有关.(2)安德森断层参数A∅显示帕米尔高原北缘与西侧区域为逆断层应力状态,在高原内部为正断层应力状态,这与GPS应变的结果显示的应变主要集中在主帕米尔断裂与阿莱谷地附近而在高原内部应变较低是一致的,另外应力在喀喇昆仑断裂北段的方向基本平行于断层走向,以及断层北端较低的滑动速率,这说明了地壳挤压缩短可能是帕米尔高原主要的的构造变形特征,并不支持由于边界走滑断裂导致的应变分异或者块体挤出的模式.(3)综合考虑地震应变方向与SHmax从帕米尔北部NNW-SSE方向到天山北部的近N-S方向的转换,GPS应变方向在帕米尔高原两侧盆地都存在不同程度的旋转,应力场安德森参数A∅显示的应力状态以及SKS的结果显示的近ENE-WSW方向,我们认为印度板块向北推挤与天山造山带碰撞导致帕米尔高原不对称的径向逆冲是帕米尔高原现今构造变形的主要成因与构造模式.     

Crustal Architecture,Geochemistry and Geochronologyofthe Ophiolitesand Ophiolitic Mélangesin Southeastern Anatolia

正The Neotethyan ophiolites exposed in SE Anatolia–Syria occur along two,ENE-WSW-trending,sub-parallel belts(Fig.1).The ophiolites and ophiolitic mélanges in the southern belt include the Cretaceous K?z?lda?(Hatay),     

沙丘移动的研究现状与未来研究思路

沙丘移动的研究经过数十年的发展与完善,基本上已自成体系。但是由于起步较晚,加之现象的复杂性,目前仍有很多重要的理论问题没能彻底解决,至少还未达成共识,成为学术界长期以来争论的焦点,从而影响了它的继续发展。本文在剖析沙丘移动研究现状的基础上,浅析其未来研究思路。重点对沙丘移动的判定指标进行了讨论,指出了Lancaste(r1988)提出的指标表达式不能够直接应用于我国,必须建立与我国国情相符合的指标体系。     

Effect of weather conditions on the incidence of Lophodermium yellow needle blight in the dwarf mountain pine in the Karkonosze and Izerskie Mountains (Poland)

The study aimed to determine, by using a statistical model, the effect of weather conditions on the incidence of Lophodermium yellow needle blight causing by new species for science- Lophodermium corconticum, in the mountain dwarf pine growing in the subalpine Karkonosze Mountains and the Izerskie Mountains(Poland). Needles showed symptoms of yellow spots, gradual discolouration and premature fall in July. The assessment of healthiness of infected mountain dwarf pine needles spanned three years(2011- 2013) and was conducted in several test sites in the Karkonosze and Izerskie Mountains. The results were analyzed by taking into account the meteorological conditions. Field observations seem to indicate that the highest infestation of mountain dwarf pine occurs in June and July, while September and October see a significantly lower disease index in the Karkonosze Mountains. The lower indices of the infestation of mountain dwarf pine are characteristic for the vegetation in the Hala Izerska high mountain pasture; whereas the environmental conditions prevailing in the Kocio? Ma?ego Stawu cirque and above the Samotnia hostel are conducive to the development of Lophodermium yellow needle blight.     

Refining the Stratigraphy of the Taghdout Group by Using the U-Pb Geochronology of the Taghdout Sill(Zenaga inlier,Anti-Atlas,Morocco)

正The Anti-Atlas belt of southern Morocco is situated on the northern edge of the West African craton(WAC).It corresponds to a broad anticlinorium some 800 km long and 200 km wide,trending ENE-WSW,parallel to the     

Neoarchaean-Palaeoproterozoic Mafic Dyke Swarms from the Singhbhum Granite Complex,Singhbhum Craton,Eastern India: Implications for Identification of Large Igneous Provinces and Their Possible Continuation on Other Formerly Adjacent Crustal Blocks

正The Singhbhum craton of the eastern India consists of the Singhbhum Granite Complex(SGC)and the Chotanagpur Gneissic Complex(CGC)separated by the Singhbhum Mobile Belt(SMB).The CGC is intruded by Mesoproterozoic as well as Cretaceous mafic dykes;in     

Geochronology of Mafic Intrusions

正Baddeleyite(ZrO_2)is today recognized as a key mineral for dating the emplacement of mantle-derived rocks such as gabbros,alkaline(Si-poor)rocks and dolerite dykes and sills,but also in hydrothermally-driven deposits(Heaman     

新疆伽师MS6.4地震前地磁日变化异常分析

以新疆伽师M S6.4地震为案例,利用地磁日变化异常分析方法,对中国地磁台网所记录的地磁观测资料进行分析,结果显示:1、离震中最近的喀什台震前59 d和39 d出现一组逐日比高值异常,排除干扰,且地磁日变形态也出现明显的畸变,异常集中于震中附近台站,震中位于异常阈值线附近;2、震前,新疆及周边地区出现地磁垂直分量日变化幅度的极小值时间在空间上出现地磁低点位移现象,低点时间分界线横穿南天山西段,呈现近EW走向分布,分界线两侧低点时间相差超过2 h,发震日期为异常发生后的38(41±4)d,震中位于低点位移分界线附近;3、地磁逐日比和低点位移异常的发生时间和空间分布可能与伽师M S6.4地震的孕育和发生有非常高的关联性。该研究进一步推广和检验了地磁日变化异常分析方法在地震预报方面的应用。     

Mesozoic Evaniidae (Insecta: Hymenoptera) in Spanish Amber: Reanalysis of the Phylogeny of the Evanioidea

<正>One new genus and five new species of the family Evaniidae are described from the Early Cretaceous (Albian)Spanish amber of Penacerrada-Ⅰ(Province of Burgos),San Just and Arroyo de la Pascueta(both in the Province of Teruel):Cretevania alonsoi sp.nov.,C.montoyai sp.nov.,C.alcalai sp.nov.,C.rubusensis sp.nov.,and Iberoevania roblesi gen.and sp.nov.Taxonomic changes include Cretevania pristina(Zhang and Zhang,2000) comb.nov.,C.exquisita(Zhang,Rasmtsyn,Wang and Zhang,2007)comb.nov.,C.vesca(Zhang,Rasnitsyn,Wang and Zhang,2007)comb.nov.,and C.cyrtocerca(Deans,2004)comb.nov.,as a result of the reinterpretation of the genera Procretevania and Eovernevania.The new well preserved specimens of the genus Cretevania,together with the characters shown by the type specimens of the synonymized genera,give new information about their anatomical characters of taxonomical importance,and the genus Cretevania Rasnitsyn,1975 is re-diagnosed.The holotypes of the Russian species in amber have been revised.A cladistic analysis of fossil and extant groups of the superfamily Evanioidea is included.Cretevania had a wide palaeogeographic distribution,with the highest diversity known from Spain.The 13 known Cretevania species show a high interspecific variation mainly in wing characteristics,and a wide range of body and wing size.