古代青铜器基体与其锈蚀产物铅同位素对比研究

利用Finnigan MAT262质谱仪和ICP—AES测试了不同地区出土的青铜样品的锈蚀产物和基体的铅同位素比值及其化学成分，以研究铅同位素在青铜器腐蚀过程中是否发生变化，以及是否存在因不同产地铅料混用引起的混合不均匀现象．结果初步显示，铅同位素组成不受青铜器锈蚀的影响，可以用锈蚀产物的铅同位素比值代替其基体的；同时，不同产地铅料在青铜器中的混用且又混合不均，可能造成青铜器基体的铅同位素比值和锈蚀产物的明显不同．     

Isotopic characteristics of the postorogenic granites in orogenic belt of northern China and their implications in crustal growth

The orogenic belt of northern China is characterized by widely developed postorogenic Ⅰ fractionated and A-type granites in the Phanerozoic. The isotopic data display relatively high ε Nd(t) and 206Pb/ 204Pb values and low I Sr ratio. The low T DM model ages (<100 Ma) suggest that the Neo-Proterozoic-Phanerozoic is one of the main stages in the continental growth.     

Recent progress of deep seismic experiments and studies of crustal structure in northern South China Sea

The South China Sea (SCS) is one of the largest marginal seas in the western Pacific. Its northern part has the features of a passive continental margin. The studies of deep crustal structure in this area are very important for understanding the tectonic nature, evolution history, basin formation of the northern margin, and the origin of the SCS. In the past decades, the deep seismic experiments of crustal studies in the northern SCS have gone through three stages, namely the sonobuoy, two-ship Expanding Spread Profile (ESP), and Ocean Bottom Hydrophone/Seismometer (OBH/OBS). Along the continental slope, the sonobuoy experiments provided useful information about the velocity structure of the upper crust, while the ESP data recorded for the first time the seismic signals from deep crustal structure and Moho interface. And the OBH/OBS profiles revealed the crustal structure in much greater detail. This paper first gives a brief historical review of these deep seismic experiments and studies, then a summary of the latest progress and important research results. The remaining problems and suggestions for further research work are presented as conclusive remarks.     

一种改进的基于节点相异度的社团结构划分算法

提出一种改进的基于节点相异度的社团结构划分算法.首先根据度和平均度评估标准,筛选出核心节点作为初始核心节点集,然后基于节点相异度进行划分,直至社团结构划分完成.实验结果证明,与其他一些算法相比,该算法的划分效果比较精确且易于实现.     

华北克拉通北缘早白垩世岩石圈减薄: 钾玄岩的Pb同位素证据

内蒙古四子王旗地区出露的早白垩世玄武岩属于钾玄岩。岩石富集大离子亲石元素（LILE）、轻稀土元素（LREE）,亏损高场强元素（HFSE）,其地球化学特征总体与洋岛玄武岩(OIB)相似。w(Rb)/w(Nb)、w(K)/w(Nb)、w(Zr)/w(Nb)、w(Th)/w(Nb)和w(Th)/w(La)比值主要落在EM1-OIB范围内。w(²⁰⁶Pb)/w(²⁰⁴Pb)、w(²⁰⁷Pb)/w(²⁰⁴Pb)和w(²⁰⁸Pb)/w(²⁰⁴Pb)分别变化在17.18～17.81, 15.40～15.50和37.54～38.05之间,岩石的Pb同位素组成接近EM1型地幔端元。随着Pb含量(质量分数)的增加,Pb同位素比值几乎没有变化,表明四子王旗钾玄岩没有经历明显的地壳物质混染。钾玄质母岩浆源于软流圈地幔的减压低度部分熔融。四子王旗钾玄岩是华北克拉通岩石圈减薄事件的产物。     

LA-(MC)-ICPMS U-Pb zircon geochronology and Lu-Hf isotope compositions of the Taihua complex on the southern margin of the North China Craton

Widely distributed on the southern margin of the North China Craton, the Taihua complex extends roughly in an east-west direction and the relatively complete successions are found in Lushan County, Henan Province. Like many other Archean terranes, the Taihua Complex can be divided into two major lithological units along the Dangze River, namely gneisses series and supracrustal rocks. The former is located on the north side of the river and chiefly composed of TTG gneisses and amphibolites; the latter on the south side of the river is mainly supracrustal rock. Coupled with the previous studies, the results obtained by this study show that the Taihua complex was formed in a large time span from Neoarchean to Palaeoproterozoic. The TTG gneisses and amphibolites are dated at Neoarchean (2794–2752 Ma). The 2.9 Ga and 3.1 Ga zircons in amphibolites could be xenocrysts. In the North China Craton, the 2.8–2.7 Ga old rocks crop out in several areas e.g. western Shandong Province, Jiaodong Peninsula and Lushan area of Henan Province. In addition, 2.8–2.7 Ga detrital zircons or xenocryst zircons have been recognized in Huai’an, Fuping, Wutai areas of North China Craton and also reported in the Early Paleozoic diamondiferous kimberlites in Mengyin and Fuxian. All these age results indicate that the 2.8–2.7 Ga rocks may have been developed much broader region than today’s outcrops. Zircon Hf and whole rock Nd isotopes show that the 2.8–2.7 Ga tectono-thermal event represents an important period of crustal growth with minor ancient crust reworked in the North China Craton. However the formation of supracrustal rocks is limited to 2.2–2.0 Ga in the Palaeoproterozoic time, not the Archaean, as previously believed. Combined with the chronological data of aluminium-rich metamorphic rocks (Khondalite series) on the southern margin of the North China Craton and adjacent areas, it is suggested that the above areas have widely developed Paleoproterozoic passive continental margin environment.     

Deep crustal structure of Baiyun Sag,northern South China Sea revealed from deep seismic reflection profile

This paper discusses deep crustal architecture of the Baiyun Sag of the Pearl River Mouth Basin, northern South China Sea based on velocity analysis, time-depth conversion and seismic interpretation of the deep seismic reflection profile DSRP-2002. The profile was acquired and processed to 14 S TWT by the China National Offshore Oil Corp. (CNOOC) in 2002. It extends across the Baiyun Sag of the Pearl River Mouth Basin, from the northern continental shelf of the SCS to the deepwater province. As the first deep seismic reflection profile in the Pearl River Mouth Basin, this profile reveals seismic phases from basement down to upper most mantle. The Moho surface appears in the profile as an undulating layer of varying thickness of 1-3 km. It is not a single reflector interface, but a velocity gradient or interconversion layer. The crust thins stepwisely from the shelf to the continental slope and the abyssal plain (from north to south), and also thins under depocenters. The crustal thickness is only 7 km in the depocenter of the main Baiyun Sag, which corresponds to a Moho upwelling mirroring the basement topography. In the lower slope and the ocean-continental transition zone of the southernmost portion of the profile, three sub-parallel, NW-dipping strong reflectors found at depths around 10--21 km are interpreted as indications of a subducted Mesozoic oceanic crust. Crustal faults exist in the northern and southern boundaries of the Baiyun Sag. The intense and persistent subsidence of the Baiyun Sag might be related to the long-term activity of the crustal faults.     

Helium isotopic study on mantle degassing in the Altay orogenic zone, China

New helium isotopic data of ores and rocks from the Altay orogenic zone, Xinjiang, China are reported, which show that the pegmatites from No. 3 vein in the Keketuohai area have high³He/⁴He ratios up to 1.795 × 10⁻⁶ and 2.54 × 10⁻⁶. Such a result suggests that the metallogenic process of rare metal deposits in the Altay orogenic zone might be related to mantle degassing.     

南大别变质块体温压结构的初步探讨

根据对太湖地区大坝附近榴辉岩的峰期变质P-T条件的研究,以及前人对南大别榴辉岩的P-T条件的分析,同时结合榴辉岩的空间分布状态的研究,文章认为南大别变质块体自北向南可分为金刚石、柯石英榴辉岩、石英/柯石英榴辉岩和石英榴辉岩4个变质单元;变质P-T条件总体上显示逐渐降低的趋势,反映了南大别变质块体俯冲时的连续性,而现今榴辉岩的P-T分布型式则代表南大别多板片的折返状态。     

Tectonic affinity of Paleozoic stratigraphic slices along the northern margin in Dabie Orogen, central China: evidence from Pb isotope of rocks

Metavolcanic and metasedimentary rocks from the Paleozoic tectono-stratigraphic units along the northern margin in the Dabie orogen show that there are two types of Pb isotopic compositions, which have some affined regularity with tectonic subdivision. Compared with the main tectonic units of the Qinling orogen, the Dingyuan Formation should be the part of the South Qinling orogenic belt or the northern margin of the Yangtze craton, characterized by less radiogenic Pb isotopic composition, and the Guishan Formation, Nanwan Formation-Foziling Group and the Carboniferous should be the part of the North Qinling orogenic belt which is extended to the east, characterized by more radiogenic Pb isotopic composition. These facts combined with the distribution of the geological units suggest that the Paleozoic subduction zone between the Yangtze and North China cratons should be located in the north boundary of the Nanwan Formation-Foziling Group or somewhere that is covered by the Nanwan Formation-Foziling Group now. From the Pb isotopic evidence and suggestion presented here, one aspect of the constraint is provided for determining the position of the Triassic collision suture between the two cratons.     

草酸在铅阴极上还原反应的机理探讨

本文用稳态极化曲线法和线性电位扫描法,研究了草酸水溶液在铅阴极上的电化反应机理,从电极催化观点提出一个 EC 机理模型,实验证实了模型,从而为电极材料的选择和工艺条件的设计提供了依据.     

豫西栾川中鱼库锌(铅)矿床闪锌矿Rb-Sr年龄及其地质意义

中鱼库矽卡岩型锌(铅)矿床位于华北陆块南缘河南省西部栾川Mo-W-Pb-Zn-Ag多金属矿集区南部,矿体呈层状-似层状赋存于新元古界栾川群三川组碎屑岩、碳酸盐岩地层中.因缺乏精确的成矿年代学研究,对该矿床成因的争议较大.本文在矿床地质背景和岩石矿物学研究的基础上,对13件矿石样品中的闪锌矿进行Rb-Sr同位素年代学研究.闪锌矿87 Rb/86 Sr和87 Sr/86 Sr同位素比值分别集中在0.802～18.98和0.713 359～0.748 684,二者具有良好的线性关系;其等时线年龄为(136.4士0.8) Ma (2σ,MSWD=3.6),(87 St/86 Sr)t=0.711 913士0.000 074.Rb-Sr同位素年龄反映该矿床形成于早白垩世,稍晚于研究区内的斑岩-矽卡岩型Mo-W矿床(146士2 MaB.P.),与区内最后一阶段花岗质岩浆活动(142～136MaB.P.)有关,属于栾川Mo-W-Pb-Zn-Ag多金属成矿系统.结合区域资料,认为该矿床形成于中生代陆-陆碰撞过程中由挤压向伸展转变的阶段,或碰撞后造山的局部伸展背景.     

大渡河金川水电站区域地壳稳定性定量化评价

金川水电站地理位置处于不同构造单元的多组构造交汇复合地带,新生代以来构造活动、地震活动和水热活动均较强烈.为服务于大渡河金川水电工程规划建设的需要,作者对大渡河流域金川地区进行了地壳稳定性评价.依据地壳稳定性定量评价的原则和方法,将地壳稳定性划分为四个等级:稳定、次稳定、次不稳定和不稳定.综合各项研究资料确定定量评价指标,并采用模糊数学方法对地壳稳定性进行综合评价,结论表明,该地区适宜修建大型水电工程.     

铅锑复合渣于低温真空蒸发直接制备纳米Sb2O3

以铅锑复合渣为原料,用低温真空蒸发法直接制备纳米Sb2O3.通过XRD、激光粒度仪、SEM和白度仪分别对Sb2O3的结构、形貌、粒度和白度进行表征,探讨温度、残压、时间等对Sb的蒸发率以及Sb2O3的纯度、白度和粒度的影响.研究结果表明：在温度为893 K、残压为250 Pa和时间为2 h的条件下,纳米Sb2O3具有立方晶型,其平均颗粒粒度为72 nm,比表面积为15.5 m^2/g,白度为90.0%,纯度为98.50%.     

铅处理对小麦种子萌发和幼苗生长的影响

以小麦种子为材料,研究了不同浓度的铅(Pb)溶液对小麦种子的发芽、幼苗生长、幼苗叶片丙二醛(MDA)含量和细胞膜透性的影响.结果表明,高浓度的Pb可延缓和抑制小麦种子的萌发和幼苗生长;侧根、主根和芽对Pb的敏感程度为侧根＞主根＞芽;小麦幼苗在低、中浓度的Pb胁迫下通过增加侧根数来抵御Pb胁迫;高浓度Pb2 使膜脂过氧化产物MDA含量升高,使膜透性增加.     

大别山区旅游经济联系空间结构特征及驱动因素

以大别山区24个县(市)为研究对象,选取2011年、2014年、2017年3个年份旅游经济指标数据,基于引力模型和社会网络分析法,分析网络密度、中心度、核心—边缘、凝聚子群等旅游经济空间结构特征,运用QAP分析法,探讨旅游经济空间特征影响因素.研究结果表明：1) 大别山区旅游经济网络发育程度低,区域旅游经济联系不紧密,旅游经济网络化发展有待加强;2) 2011—2017年间大别山区核心区数量减少,存在明显核心-边缘结构,核心区对边缘区带动作用强;3) 麻城市中心度高,旅游经济发展好,领导控制作用强,但易导致过度依赖,使大别山区旅游经济网络呈现脆弱性特征;4) 大别山区凝聚子群划分行政壁垒严重,同一子群联系紧密,不同子群联系薄弱,旅游经济一体化程度低;5) 区位交通条件和旅游发展能力对大别山区旅游经济发展影响显著,区域经济水平影响较小.     

南兴安岭晚中生代火山岩的岩石成因(II):Pb同位素制约

 对南兴安岭地区晚中生代火山岩的Pb同位素进行了分析,结合其主微量元素和Sr-Nd同位素地球化学特征,探讨了火山岩的岩石成因。满克头鄂博组低钾拉斑-钙碱性玄武安山岩表现出富集LILE、LREE和HFSE亏损元素地球化学特征以及稍高放射性成因Sr、Pb (⁸⁷Sr/⁸⁶Sr=0.704 88～0.704 99; ²⁰⁶Pb/²⁰⁴Pb=18.18～18.23)和弱相对亏损至弱富集的Nd同位素组成(ε_Nd((t)=-0.12～+0.68),其来源于俯冲沉积物参与改造富集地幔熔融源区。该组的英安岩-流纹岩较基性岩浆具有稍高放射性成因Sr、Pb (⁸⁷Sr/⁸⁶Sr=0.705 22～0.707 09; ²⁰⁶Pb/²⁰⁴Pb=18.16～18.33)和低Nd同位素组成 (ε_Nd(t))=-1.5～-0.4), 且在空间上与玄武岩共生,为玄武质岩浆结晶分异,并同化混染作用 (AFC)的产物。玛尼吐组英安岩具有与现代俯冲带adakite岩石相似的特征;在Sr-Nd-Pb同位素组成上,它们较同期或近期玄武安山岩更低Sr、Pb (⁸⁷Sr/⁸⁶Sr=0.704 09~0.704 25;²⁰⁶Pb/²⁰⁴Pb=18.15~18.17)和高Nd同位素比值(ε_Nd((t))=+0.9~+2.1),为造山带下地壳镁铁质岩石的部分熔融产物。