江汉盆地当阳向斜区主要不整合面剥蚀厚度

本文利用磷灰石裂变径迹、(U-Th Sm)/He及镜质体反射率Ro％等古温标方法综合分析了江汉盆地当阳向斜区主要不整合面剥蚀厚度.结果表明:发育于古近纪末期不整合面T1界面累积剥蚀厚度超过1000m,且局部正反转区域如谢家湾断褶带等则遭受更大规模的剥蚀,剥蚀厚度可能超过2000m,而发育于晚侏罗世一早白垩世的不整合面T11界面累积剥蚀厚度超过4000m,且主要是晚侏罗世早白垩世构造事件的结果,表明该期剥蚀量明显大于古近纪末T1界面剥蚀量;晚三叠世—侏罗纪期间,当阳地区发育前陆坳陷带,侏罗纪堆积体具有明显东厚西薄的楔形体特征,位于盆地东部的前渊区沉积厚度可超过5000m;包括现今三叠系和侏罗系出露区以及江陵凹陷局部断隆区在内的前白垩系在侏罗纪前陆坳陷带发育时期达到最大埋深和最高古温度,其Ro％主要是该期获得的;晚白垩世—古近纪发育的断陷盆地范围可能远比现今残留盆地分布广,江陵凹陷上白垩统—古近系厚度超过9000m,其中古近系可能超过7000m,而在河溶凹陷谢家湾断褶带古近系厚度可超过3300m.     

三维Douglas-Peucker算法的等高线间接综合方法研究

提出一种用三维Douglas-Peucker算法综合无格式离散点,再回放等高线,进而将其作为综合结果的等高线间接综合方法,并进行编程验证。初步试验证明,在主要地貌结构线辅助下,用该方法综合的等高线兼具几何精确性与拓扑一致性,且方法本身对等高线的输入输出形式适应性较强,具有良好的应用前景。     

一种基于曲率法的曲线特征点选取方法

本文提出使用弯曲树来组织曲线的弯曲形态,根据弯曲特征以一定范围计算曲线弯曲程度所得到的值度量点的宏观弯曲量,作为特征点的选取标准;并根据微观弯曲量微调领域内特征点的位置,来确定特征点。实验对比发现,本算法可以在一定程度上克服传统曲率算法的不足,选取的特征点能够控制曲线的宏观形态,并且位置准确。     

EXPERIMENTS ON THE GROUP GENERALIZATIONG OF CONTOUR LINES FOR TOPOGRAPHIC MAPS

ABSTRACT

This paper analyzes the advantages and disadvantages of two technical lines for automatic group generalization of contour lines. The author suggests that it is possible to get faster and better generalization results if we simulate the intelligence of human experts in program designing, retrieve geomorphological structural information using the input data of 2-D contour lines and derive and output the generalized 2-D results directly.     

带有劳动收入的最优消费和投资问题研究进展

现代投资组合理论一直是金融工程中活跃的研究方向.首先阐述了消费-投资组合问题的研究现状,介绍了不同时期国内外学者的研究成果和方法,接着较为详细地论述了带有劳动收入的最优消费和投资组合问题并给出了所要研究的模型,即含有时变的投资机会和动态劳动收入的模型,最后给出所要研究模型在通胀环境和Knight不确定下的拓展框架.     

基于CLUE-S模型的深圳海岸带土地利用变化模拟

以深圳海岸带为研究区,基于1996、2005、2011年遥感影像得到研究区土地利用历史数据,选取自然、社会统计数据作为驱动因素,利用CLUE-S模型分别从不同时间尺度和空间尺度对研究区2005、2011年的土地利用分布予以模拟,并对模拟结果分别从类别和景观水平予以精度评价。从类别水平角度,选择ROC曲线对各地类的Logistic回归拟合精度进行评价;从景观水平角度,选取Kappa指数对模拟效果予以评估,以验证所选驱动因子的合理性。结果表明:在研究区范围内,CLUE-S模型的类别精度随着空间分辨率的改变而有所差异,100 m分辨率为本研究模拟的最佳尺度,各地类的ROC值均高于0.7;随着模拟时间的缩短模拟精度有所增加;东海岸由于受到人类影响较小,模拟效果整体相对较好。总体而言,CLUE-S模型适用于研究区土地利用模拟,所选驱动力因子能够对研究区土地利用变化予以较好的解释。     

西藏措勤隆格尔铁矿岩体成岩时代及其地质意义

西藏措勤县的隆格尔铁矿位于拉萨地块隆格尔-工布江达弧背断隆带的西段,是冈底斯西段中生代矽卡岩型铁矿中重要的矿床之一。野外和室内工作表明,隆格尔铁矿床属矽卡岩型铁矿,与成矿有关的岩体为粗粒二长花岗岩。因此,本文通过对隆格尔铁矿成矿岩体的LA_ICP_MS和SHRIMP锆石U_Pb定年来探讨其成矿时代。分析结果表明:隆格尔粗粒二长花岗岩年龄为115.5±2.1 Ma,可近似代表铁成矿年龄。隆格尔铁矿与其东侧同处于同一构造单元内的尼雄铁矿床成岩成矿年龄为110~116 Ma,两者间的洛布勒铁矿床的成岩成矿年龄为111.3±1.6 Ma。这些铁矿床处于相同的构造单元,具相似的成矿特征和相近的成岩成矿年龄,构成一条东西向展布的早白垩世矽卡岩型铁矿成矿带,并可能向西延伸包括帮部勒、龙认拉、查加寺等矽卡岩型铁矿床。该带上还发育有晚白垩世的矽卡岩型铜金矿床,如日阿铜金矿床,成矿年龄均为87 Ma。因此,这一成矿带应当具有相同或相似的地质背景和构造-岩浆演化过程。隆格尔铁矿床乃至整个成矿带成铁的岩浆活动可能与洋壳断离前的板片回卷过程相关,成铜金的岩浆活动可能与洋壳断离过程相关,而矿区内石英闪长岩的侵入处于两者之间。     

Chronology and Crust-Mantle Mixing of Ore-forming Porphyry of the Bangongco: Evidence from Zircon U-Pb Age and Hf Isotopes of the Naruo Porphyry Copper-Gold Deposit

The Naruo porphyry copper-gold deposit(hereinafter referred to as the Naruo deposit) in Tibet is a potentially ultra-large, typical gold-rich porphyry copper deposit, which was recently discovered in the Bangongco-Nujiang metallogenic belt. This study analyzed U-Pb chronology and Hf isotopes of the ore-bearing granodiorite porphyry in the Naruo deposit using the LA-ICPMS dating technique. The results show that the weighted average age is 124.03±0.94Ma(MSWD=1.7, n=20), and 206Pb/238 U isochron age is 126.2±2.7 Ma(MSWD=1.02, n=20), both of which are within the error. The weighted average age represents the crystallization age of the granodiorite porphyry, which indicates that the ore-bearing porphyry in the Naruo deposit area was formed in the Early Cretaceous and further implies that the Neo-tethys Ocean had not been closed before 124 Ma under a typical island-arc subduction environment. The εHf(t) of zircons from the granodiorite porphyry varies from 2.14 to 9.07, with an average of 5.18, and all zircons have εHf(t) values greater than 0; 176Hf/177 Hf ratio is relatively high(0.282725–0.282986). Combined with the zircon age―Hf isotope correlation diagram, the aforementioned data indicate that the source reservoir might be a region that is mixed with depleted mantle and ancient crust, which possibly contains more materials sourced from depleted mantle. Rock-forming ages and ore-forming ages of the Duolong ore concentrate area are 120–124 Ma and 118–119 Ma, respectively, which indicate 124–118 Ma represents the main rockforming and ore-forming stage within the area. The Naruo deposit is located in the north of the Bangongco-Nujiang suture, and it yielded a zircon LA-ICPMS age of 124.03 Ma. This indicates the Bangongco-Nujiang oceanic basin subducted towards the north at about 124 Ma, and the Neo-tethys Ocean had not been closed before the middle Early Cretaceous. It is possible that the crust-mantle mixing formed the series of large and giant porphyry copper-gold deposits in the Bangongco.     

Luoping Biota: Representative of the Third Biological Radiation

<正>The third biological radiation refers to the Middle Triassic biological radiation in the world.In 2007,the China Geological Survey during field investigations of the project"Regional Geological Survey in Datong,Guishan,Luoping County and Pengzha at a scale of 1:50000 in Yunnan Province"first discovered and named the Luoping Biota(Fig.1).This Middle Triassic biota emanates from     

New Technology “Flotation to Form Agglomerates and Magnetic Separation” Allows Great Breakthrough for World Low-Grade Light Rare Earth Ores

<正>Rare earth resources are relatively scarce worldwide,but their global consumption is increasing year-by-year.At present,China has about 36%of the global rare earth reserves,but provides 90%of the world’s supply,which has generally met world demand and promoted the development of the world economy.In order to continuously and stably supply rare earths to international markets,the Chinese Government has financially