ENSO事件对东亚副热带西风急流影响的诊断分析

本文利用NCEP/NCAR月平均再分析资料,用合成分析和相关分析方法就ENSO事件对东亚副热带西风急流的影响进行诊断分析.主要结论为:El Nino年冬季200 hPa东亚副热带西风急流主要在急流出口区纬向风有正距平,急流增强东扩.而La Nina年冬季急流在急流出口区纬向风有负距平,急流减弱西移.El Nino年夏季急流增强,主要在急流区内的偏南部纬向风有正距平.La Nina年夏季急流减弱,主要在急流区内的偏南部纬向风有负距平;相关分析表明东亚副热带西风急流冬、夏季纬向风与热带中东太平洋冬、夏季海表温度有显著的相关.研究表明,ENSO年冬、夏季对流层中上层有较大的气温异常,并由此产生大的经向温度梯度的异常,这可能是ENSO事件影响东亚副热带西风急流的原因之一.     

东天山喀尔里克山北坡-淖毛湖植物群落物种多样性研究

以东天山喀尔里克山北坡-淖毛湖为研究区,探讨了该区山地-荒漠生态系统的植物种类组成、植被类型及群落物种多样性特征.结果表明:该区共有高等植物33科93属133种,植物生活型组成以草本植物居多.群落物种多样性测度指数的主成分分析结果显示,物种丰富度指数(R)、Pielou均匀度指数(Jsi)、Shannon-Wiener多样性指数(H)和Simpson优势度指数(C)能很好地描述群落结构和组成特征.其中,多样性指数、均匀度指数和丰富度指数的变化趋势基本一致,优势度指数则和前三者呈负消长的关系.随着海拔升高,群落物种多样性指数、丰富度指数和均匀度指数变化均呈现单峰分布格局,即植物群落的物种多样性在山前荒漠生态系统和高海拔山地生态系统中较低,而在中海拔地区达到最大.     

山西沁水盆地热史演化特征

沁水盆地是华北克拉通内的构造盆地,是天然气勘探的潜在重要区域,盆地的热史研究是天然气储层评价的重要基础。重点应用磷灰石裂变径迹的分析与模拟,配合镜质体反射率的分析与模拟以及区域构造地质背景分析,恢复了沁水盆地的古地温梯度和地热演化模型:早古生代地温梯度稳定,为3℃/100 m,晚二叠世至三叠纪地温梯度较前期略有降低,约为2.5~3.0℃/100 m;早、中侏罗世地温梯度开始上升,约为3.0~4.0℃/100 m;晚侏罗世—早白垩世地温梯度大幅度上升,为4.5~6.5℃/100 m;晚白垩世至古近纪早、中期为高地温场的延续时期,地温梯度为5.5~6.5℃/100 m;古近纪晚期—新近纪早期地温梯度大幅度降低,从6.0℃/100 m骤降至4.2℃/100 m左右;中新世以来地温场逐渐趋于稳定,地温梯度由4℃/100 m演变到接近现代地温场的3℃/100 m左右。     

基于梯度对称性的无人机影像电力线自动提取方法

针对航空影像电力线提取过程中,背景线特征(电力杆塔、道路和植被等)干扰问题和电力线提取准确性问题,提出一种基于梯度对称性的电力线特征判别方法。采用Line Segment Detector(LSD)算法,对航空影像进行线特征提取;基于电力线附近梯度的对称性特征,实现从大量线段中准确筛选电力线段;采用缓冲区序列化线段连接算法,实现了电力线的自动连接。通过实验证明,提出的方法能够排除背景干扰并准确、完整地提取整条电力线。     

Água Bonita pull apart basin and its relationship to Transbrasiliano Lineament

The Transbrasiliano Lineament (TBL), a NE-SW trending strike slip system at least 2700 km long, is one of the main structures of the South American Platform. This lineament, along with other structures, influenced greatly the installation and depositional history of the Paraná and Parnaíba sedimentary basins. The Água Bonita Basin (ABB) occurs at an intermediate position between both basins. This work aims to provide information on the origin and evolution of the Água Bonita Basin, considered a Silurian-Devonian basin, as well as its relationship with the Transbrasiliano Lineament.Geological, aero and ground geophysics data were used to determine a structural geological model for the ABB located in the Brasilia Fold Belt in the Tocantins tectonic province. The airborne geophysical magnetic data used in the study were acquired in the 1970s by the existing 147 ground gravity stations in addition to the 498 new ground gravity and geodetic stations that were added to the existing ones.The analysis of the outcrops allowed identifying the sedimentary facies associations providing new information on the depositional environments. The compilation of existing data, satellite images analysis, geological maps and shaded relief provided an integrated model for the study area.A geological model was proposed for the ABB based on the interpretation, integration, depth analysis and 2D gravity forward modeling according to a theoretical model for an extensional duplex in a strike slip system with flower structures. We observed several segmented gravity anomalies, which were interpreted as steps/faults. This interpretation is consistent with a pull apart basin. According to the depth data estimated by this model, the maximum thickness of the Água Bonita Formation is 1.6 km and 2.4 km for the precursor rift. The basin has two dextral faults on each border, whose main fault of the TBL strike slip system and the master fault controlling the ABB are observed on the east border of the rift phase. Lineaments perpendicular to the west edge, in addition to those crossing the ABB in the N65E, delineate peculiar magnetic, gravity and geological signatures in the northern part of the basin. The basin is located in the weak region of the TBL and its main eastern fault is dipping sub-vertically to the west. This fault modeled up to the 8 km depth using the gravity data, was also observed in the Tilt Angle of the Total Horizontal Gradient (TAHG) matched filter grid result at approximately 8 km, however this may not be this fault maximum depth.Three main sedimentary-tectonic stages were observed, (i) a Pre-Devonian precursor rift present in the Água Bonita Basin and Jaibaras Group; (ii) the sag stage developed during the Devonian, when the Paleozoic basins of Paraná, Parnaíba and Água Bonita Basin were connected evidenced by the sedimentary facies and similar thicknesses; and (iii) the Pos-devonian rocks that are probably not preserved in the Água Bonita Basin.     

冻结作用下考虑补水层影响的水分迁移试验

冻融协同淋洗修复污染土壤的过程中,为了提高淋洗效率,须使土体在冻结过程中吸收更多的水分或淋洗液。因此,通过室内大尺寸单向冻结水分迁移试验,开展了开放系统下温度梯度、冻结速率及补水方式对水分迁移的影响研究。试验结果表明：冻结过程中土中水分迁移与温度梯度的变化速率有关,变化速率越大水分迁移量越大;可以通过边界温度控制冻结锋面推移速度进而影响土中水分的迁移,当冻结锋面推移速度为0.5 cm·d^-1左右时,补水速率最大;距离冻结锋面越近水分迁移量越大,当距离冻结锋面10 cm左右时,水分迁移量开始增大,可通过在土体中添加多层补水层的方式让土体吸收更多的水分;有外界水源的补给下土体含水量整体增加,但上层土体含水量增加较多,下层土体含水量增加较少。     

Present Terrestrial Heat Flow Measurements of the Geothermal Fields in the Chagan Sag of the YingenEjinaqi Basin,Inner Mongolia,China

Owing to the lack o f terrestrial heat flow data, studying lithospheric thermal structure and geodynamics of the Yingen-Ejinaqi Basin in Inner Mongolia is limited. In this paper, the terrestrial heat flow o f the Chagan sag in the YingenEjinaqi Basin were calculated by 193 system steady-state temperature measurements of 4 wells, and newly measuring 62 rock thermal conductivity and 20 heat production rate data on basis o f the original 107 rock thermal conductivity and 70 heat production data. The results show that the average thermal conductivity and heat production rate are 2.11 ±0.28 W/(m.K) and2.42±0.25 nW/m~3 in the Lower Cretaceous o f the Chagan sag. The average geothermal gradient from the Lower Suhongtu 2 Formation to the Suhongtu 1 Fonnation is 37.6 °C/km, and that o f the Bayingebi 2 Formation is 27.4 °C/km. Meanwhile, the average terrestrial heat flow in the Chagan sag is 70.6 mW/m~2. On the above results, it is clear that there is an obvious negative correlation between the thermal conductivity o f the stratum and its geothermal gradient. Moreover, it reveals that there is a geothermal state between tectonically stable and active areas. This work may provide geothermal parameters for further research o f lithospheric thermal structure and geodynamics in the Chagan sag.     

顾及梯度的高斯混合模型在三维属性场空间聚类中的应用

针对高斯混合模型(GMM)在空间聚类中由于忽视目标对象之间的空间关联性而导致的高误判率等问题,本文提出了一种顾及梯度的高斯混合模型:GMM-G,并将其应用在三维属性场的空间聚类中。GMM-G用反映标量场最大属性变化方向的梯度因子来定义邻域规则,设定梯度正交平面所通过的邻域体元更倾向于与中心体元归属于相同或相近的类别;并据此设计了符合归一性和空间连续性的空间邻域信息函数,来定义中心体元属于各类别的具有空间领域规则约束的后验概率。通过对由蒙特卡洛随机抽样构建的实验场的空间聚类结果进行对比表明,相对GMM方法,GMM-G具有更优的聚类精度及效率。最后,把GMM-G方法用于红透山铜矿区可控源音频大地电磁法(CSAMT)三维视电阻率场的空间聚类,得到了与已知岩性划分具有较高匹配度的分类结果,该方法可为物性属性场的岩性划分及地质推断提供相关的依据和参考。     

贵州深部四级断裂构造特征及与重要矿产的关系

贵州位于扬子陆块、江南造山带、右江造山带的复合部位,自新元古代以来,发生了多次重要的构造伸展运动和构造挤压变形。晚古生代之后的沉积活动,掩盖了早期地质构造形迹。多位学者曾对贵州的深部断裂进行过推断,但由于资料不足、认识差异等原因,研究存在局限和争议。在充分借鉴已有研究成果的基础上,通过综合应用重力、航磁、地质等资料,提取了贵州深部四级断裂构造体系。所推测的贵州深部Ⅰ级断裂3条,呈"H型"结构;Ⅱ级断裂15条、Ⅲ级断裂12条,基底断裂若干条,这些断裂均在上一级断裂的基础上发展演化。根据人工地震剖面资料,进一步验证了5条深部Ⅰ至Ⅲ级断裂的展布特征,发现这些断裂沿不同倾向延伸、切割深度达6~12km,为切穿沉积盖层和基底的深大断裂。结合四级断裂构造体系及贵州省内重要矿产的分布,提出贵州金、铅锌、锑、锰、磷、铝土矿分布与Ⅰ、Ⅱ、Ⅲ级深部断裂构造具有空间联系。      

Orthometric corrections from leveling, gravity, density and elevation data: a case study in Taiwan

A new orthometric correction (OC) formula is presented and tested with various mean gravity reduction methods using leveling, gravity, elevation, and density data. For mean gravity computations, the Helmert method, a modified Helmert method with variable density and gravity anomaly gradient, and a modified Mader method were used. An improved method of terrain correction computation based on Gaussian quadrature is used in the modified Mader method. These methods produce different results and yield OCs that are greater than 10 cm between adjacent benchmarks (separated by 2 km) at elevations over 3000 m. Applying OC reduces misclosures at closed leveling circuits and improves the results of leveling network adjustments. Variable density yields variation of OC at millimeter level everywhere, while gravity anomaly gradient introduces variation of OC of greater than 10 cm at higher elevations, suggesting that these quantities must be considered in OC. The modified Mader method is recommended for computing OC.Acknowledgments.This study is supported by the Ministry of the Interior (MOI), Taiwan, under the project `Measuring gravity on first-order benchmarks'. The authors are grateful to F.S. Ning and his colleagues at BSB (Base Survey Battalion) for their precision work in collecting gravity data, and to R. Forsberg for the terrain correction program. They also thank the Institute of Agricultural and Forestry Aerial Survey for elevation data and MOI for leveling data. Dr. Will Featherstone and three anonymous reviewers are thanked for their constructive comments.