U-Pb ages of Kude and Sajia leucogranites in Sajia dome from North Himalaya and their geological implications

~~U-Pb ages of Kude and Sajia leucogranites in Sajia dome from North Himalaya and their geological implications~~ FallMeetingSuppl.Abstr.,2001,0830h. 10.Lee,J.,Hacker,B.R.,Dinklage,W.S. et al.,Evolution of theKangmarDome, southernTibet:Structural, petrologic, and ther- mochronologic constraints,Tectonics,2000,19:872—895. 11.Parrish,R.R.,Roddick,J.C.,Loveridge,W.D. et al.,Ura- nium-lead analytical techniques at the geochronology laboratory,GeologicalSurvey ofCanada,Geol.Sur…     

Terrace dating as an archive of the run-through of the Sanmen Gorges

Analysis of morphological properties in the Sanmen Gorges region of the Yellow River shows that four river terraces have been developed at the entrance to the gorges. Commonly, thick aeolian loess-paleosol sequence was deposited on the terraces, which makes it easy to date the terraces. The dating of paleomagnetic, loess-paleosol sequence matching and thermoluminescence show that terraces T₂, T₃ and T₄ were formed 0.129 Ma, 0.625 Ma and 0.865 Ma ago, respectively. The formation of these terraces in this region indicates that the Yellow River has experienced four intensive downcutting events during the last 0.9 Ma. The Yellow River cut through the Sanmen Gorges and inpoured into the East China Sea no later than 0.865 Ma.     

SHRIMP U-Pb zircon dating for Qiashikansayi granodiorite, the Northern Altyn Tagh Mountains and its geological implications

The Qiashikansayi granodiorite is foliated resulting in a granodioritic gneiss. Its geochemical features, such as alumina saturation index(A/CNK) of 0.81-0.99, Na2O/K2O values>1, TiO2 contents <1.0%, LREE enrichment with high fractionation factors, weakly negative or no Eu anomalies, and significant Ba and Ti negative anomalies, suggest that it is similar to a typical island arc pluton. The trace elements of the Qiashikansayi granodiorite are plotted in the island arc field in the tectonic setting discrimination diagrams as well. Cathodoluminescence images demonstrated that the zircons have clear rhythmic crystallized zoning, without any remnant core and new crystallized rim, suggesting the zircons be magmatic ones. Their U and Th contents vary in the range of 574-870 μg/g, and 279-556μg/g respectively, with the Th/U ratio in the range of 0.52-0.68. SHRIMP zircon U-Pb dating yielded the 481.5±5.3 Ma age for the intrusion of the granodiorite, which is coeval with the island arc volcanic rocks in the no     

三维锰钒配位聚合物Mn2(phen)2(VO3)4(H2O)2的水热合成与光电子能谱的表征

三维锰钒配位聚合物Mn2(phen)2(VO3)4(H2O)2在水热的条件下被合成出来,并在元素分析、红外光谱分析、光电子能谱分析和X-射线衍射方面进行了结构表征.X-射线分析表明,此化合物是三维结构.光电子能谱分析结果显示标题化合物显示出了有意义的信号,g值为1.997说明分子中V原子呈现 4价氧化态.     

川西坳陷断裂活动期次、热流体性质和油气成藏过程分析

川西坳陷中生代陆相地层中的众多油气藏成因,与该坳陷由持续构造沉降折向脉动性隆升的重大构造逆转事件,以及隆升过程中多期次断裂活动和流体运动密切相关。通过对充填不同期次构造裂缝和溶蚀孔洞的次生石英和方解石标型特征、ESR年龄测定、流体包裹体均一温度、盐度和密度、沥青包裹体反射率,以及氧碳同位素分析的综合研究,结合众多前人研究成果,认为：该坳陷自早白垩世至中新世的断裂活动可划分为燕山晚期早幕(I期,125～110Ma)和晚幕(Ⅱ期,94～82Ma)、喜马拉雅早幕(Ⅲ期,63～53．7Ma)、喜马拉雅中期早幕(Ⅳ期,45～21.6Ma)和晚幕(V期,14．9Ma)五个主要期次;在渐趋开放的体系中,沿各期次构造裂缝运移的热流体以继承性发展演化的载烃油田水为主,但在Ⅱ期和Ⅳ期晚时混入有深部高盐度地层水;构造裂缝为油气运移、聚集和成藏作用提供了重要通道条件;相关的成藏过程为I期石油窗阶段,Ⅱ期原始油气藏阶段,Ⅲ期原生油气藏破坏和早期次生油气藏阶段,Ⅳ期次生油气藏主要成藏阶段,V期“浅层远源次生”天然气藏阶段,Ⅳ期和V期为最重要的2个关键成藏期。     

Zircon SHRIMP U-Pb dating for the Cangshuipu volcanic rocks and its implications for the lower boundary age of the Nanhua strata in South China

Continental volcanic rocks and volcaniclastic sedi-mentary conglomerates of the Cangshuipu Formation oc- cur as wedge-shaped Neoproterozoic strata in the Yiyang region, Hunan Province. They overlie with a high-angle unconformity the Lengjiaxi Group of the Upper Meso- proterozoic Eonothem. The wedge-shaped Neoproterozoic strata of the continental clastic rocks and the Mesopro-terozoic deep marine flysch turbidites of the Lengjiaxi Group represent two distinct stages of basin-tectonic evo-…     

Determination of U-Pb age and rare earth element concentrations of zircons from Cenozoic intrusions in northeastern China by laser ablation ICP-MS

Using the in situ zircon U-Pb dating method of LA-ICPMS, we analyzed the 31 Ma old SHRIMP U-Pb age of the Yongsheng nepheline syenite from southern Jilin Province under different spot sizes. The obtained ages are comparable with that of SHRIMP in both accuracy and precision. The age is also identical to that of the Yinmawanshan gabbro from the Liaodong Peninsula within error. Both the Yongsheng nepheline syenite and the Yinmawanshan gabbro represent the youngest known exposed intrusions in northeastern and even eastern China. The results indicate the Eocene mantle-derived magmatic underplating, and the rapid crustal uplifting of this region since 30 Ma. The analyses also document extremely high LREE concentrations and relatively fiat REE patterns for the zircons from the Yongsheng nepheline syenite, which represent a new type of zircon REE pattern.     

U-Pb dating of zircon grains from the ore-bearing plagioclase amphibolite in the Dashuigou Te deposit

The Dashuigou Te deposit is a unique independent one found in the world, and hosted in the plagioclase arnphibolite. The upper intercept age of single zircon from the arnphibolite can be considered to be the crystallization age of the source-rock of the amphibolite (tholeiitic basalt), while the lower intercept is nearly consistent with the time of the tectono-thermal event.     

AMS dating on glacial tills at the source area of the Urumqi River in the Tianshan Mountains and its implications

Using accelerating mass spectrometry (AMS) dating method, a dating has been made on the primary calcium carbonate in tills and secondary calcium carbonate coating on till gravel and the roche moutonnee formed since the Last Glaciation at the source area of the Urumqi River valley in the Tianshan Mountains, northwestern China. The results reveal that the carbonate content in the tills in this noncarbonate area is high enough to date by AMS, that the carbon in the coatings on the newly exposed roche moutons and in the modern till is modern carbon and so the¹⁴C dating results in the ancient till can represent the actual ages of the till formation, and that the warm period during the Holocene began as early as 6 500 a B. P. and lasted to 1 800 a B. P.     

高时间分辨电子自旋共振波谱仪设计中的几个技术问题

本文着重探讨在高时间分辨电子自旋共振波谱仪设计中的几个重要技术问题：零拍平衡混频器，宽带放大，信噪比以及信号的接收。