Discussion on origin of Pn velocity variationin China and adjacent region

IntroductionInrecentyears,theresultsfromresearchesonwavevelocitystructureofuppermostmantleusingMohorefractionwavesindicatethattheclearlateralvelocityvariationandanisotropyexistintheuppermostmantle(Hearn,1996,1999;Mele,etal,1998;WANG,etal,2002).Astotheoriginofvelocitylateralvariation,thegeneralconsiderationisthatitmayberelatedtothemate-rialcomposition,pressureandtemperatureintheuppermostmantle(Hearn,1984,1999;Beghouletal,1993).Theseismicanisotropyoftheuppermostmantleisnowanestablishedfactan…     

Geochemistry of the ophiolite and oceanic island basalt in the Kangxian-Pipasi-Nanping tectonic melange zone, South Qinling and their tectonic significance

Detailed studies indicate that Kangxian-Pipasi-Nanping tectonic zone is a complicated melange zone which includes many tectonic slabs of different origins. Ophiolite (MORB-type basalt), oceanic island tholeiite and alkaline basalt have been identified. Moreover, this tectonic melange zone is eastward connected with the Mianlue suture zone. The deformation characteristics, consisting components and volcanic rock geochemical features for the Kangxian-Pipasi-Nanping tectonic melange zone are much similar to those of the Mianlue suture zone and Deerni ophiolite. Therefore, the Kangxian-Pipasi-Nanping tectonic melange zone should be the westward extension part of the Mianlue suture zone. It indicates that the Mianlue suture zone had extended to the Nanping area.     

Geochemistry and regional distribution of ophiolites and associated volcanics in Mianle suture, Qinling-Dabie Mountains

The Mianl黣 tectonic zone has been recently identified as an ophiolitic tectonic m閘ange zone on the southern margin of the Qinling Belt[1—6]. The m?lange zone, stretching from east to west in the Mianxian-Lueyang region, represents a newly recog-nized Mianl黣 ophiolitic complex which is quite dif-ferent from the Shangdan ophiolite cropping out in the area between the North and South Qinling in terms of age and composition[1—6]. This paper is to present re-sults of geochemical studies ca…     

Comparison of eastern paleo-Tethyan ophiolites and its geodynamic significance--Evidence from Dur''ngoi ophiolite

Nd-Pb isotopic geochemistry of metabasalt from Dur'ngoi ophiolite, Qinghai Province, NW China reveals the presence of DMM mixing with EMIl components in its upper mantle source, which is comparable with present Indian MORB. Comparisons indicate that the geochemistry, chronology and source characteristics of Dur'ngoi ophiolite coincide with Paleo-tethyan ophiolites from "Sanjiang" area. Together with evidences from regional geology in adjacent areas, this study proves that independent paleo-tethyan basins evolved contemporarily,the dynamics of which is attributed to the interaction of mantle plume with over-riding lithosphere.     

一种高效的建筑物直线特征提取算法

随着遥感卫星的发射,国内影像处理事业逐渐被人们重视。高效、快速地对遥感及航测影像进行特征提取成为当前研究的热点。本次实验采用辽宁科技大学1∶2 000航拍影像图,针对教学用地建筑物直线提取中绿色植被和道路的影响,提出了一种新的直线提取算法。实验将直线拟合和Hough变换结合并进行改进,对实验结果进行对比,分析改进前后效果。实验结果表明:该方法能很好地适应复杂地形下建筑物的直线特征提取,提取速度快,有效地解决了教学用地中道路和绿色植被对建筑物直线提取的影响问题。     

一种双频载波相位周跳探测与修复方法

针对相位减伪距法只能探测出大周跳而对小周跳无能为力的问题,提出将相位减伪距法应用于双频载波相位周跳的探测与修复中。对采样率为1s、15s和30s不含周跳的观测值分别加入1周到40周不等大小的周跳,采用相位减伪距法分别对加入周跳的观测值进行处理。结果表明,该方法对于采样率为15s和30s的观测值仍然保持其优秀的大周跳探测能力,对采样率为1s的载波相位观测值则能够探测出小于1周的周跳,且其周跳探测分辨率能达到0.3周的高周跳分辨率。与其他周跳探测方法相比,该方法需要的信息量和计算量更小,效率高,算法易于计算机实现,且具有很强的实用性。     

REPORT ON THE EXCAVATION OF THE LOCALITY 13 IN CHOUKOUTIEN~1

1. INTRODUCTION When inspecting the Choukoutien area in October 1933, under the direction of the late Dr. Davidson Black, the workmen brought to the attention of the members of the Cenozoic Laboratory a fossiliferous site which had     

REPORT ON THE EXCAVATION OF THE LOCALITY 13 IN CHOUKOUTIEN~1

1. INTRODUCTION When inspecting the Choukoutien area in October 1933, under the direction of the late Dr. Davidson Black, the workmen brought to the attention of the members of the Cenozoic Laboratory a fossiliferous site which had     

紫菜丝状体DNA的提取

紫菜(Porphyra spp.)是一种大型红藻,它的孢子体世代是丝状体.丝状体适于在常温条件下(20℃左右)长期保存和培养,是筛选丝状体优良栽培品系,利用光生物反应器进行紫菜育苗的理想材料.紫菜细胞含有大量胞外多糖,主要以硫酸基多糖和羧基多糖形式存在,它们比陆生植物的中性多糖更易溶于水,与DNA产生共沉淀,从而影响限制性内切酶的消化和PCR扩增.另外,紫菜细胞DNA含量较少,DNA酶含量却很高,使紫菜DNA提取的得率不足[1].