甘肃北山造山带玉山钨矿成岩成矿时代及成矿机制

利用SHRIMP锆石U-Pb年龄测定、锆石阴极荧光图像和谱图特征分析等方法对新发现的东天山-北山钨矿带玉山钨矿床赋矿火山-沉积地层、周边花岗岩体、钨矿化火山岩(矿石)进行了精细定年, 揭示玉山钨矿成矿年龄(250 ± 9) Ma, 与二叠纪花岗岩体和中酸性喷出岩有密切的成因联系. 钨成矿作用受石炭纪主碰撞造山期后区域右行走滑剪切构造运动、拉分盆地形成、酸性岩浆活动控制, 应属东天山-北山二叠纪多金属成矿带的新增矿种.     

U-Pb zircon age for the Nanhua-Sinian boundary

China Commission on Stratigraphy approved a tripartite classification of the Neoproterozoic in 2001 . Top of the new system was assigned to the base of the Doushan tuo Formation, the glacier-related strata were separated from the pro-Sinian System and named the Nanhua System, in which Nanhua is after the term of “the Nanhua great glaciations” proposed by Prof. Liu. In March 2004,     

Identification of Mesoproterozoic zircons in a Triassic dolerite from the Liaodong Peninsula,Northeast China

Evolution of mantle and crust in all blocks of China and their relationship with the surrounding blocks are re-lated to amalgamation and breakup of the supercontinents. Studies on the Mesoproterozoic Grenvillian orogeny and the configuration of Neoproterozoic Rodinia provide the most important advances to the ideas of continental crustal growth and configuration of plates[1,2]. Recent studies show that there are geological records of assembly and breakup of Rodinia in the Cathaysia and Yang…     

Position of South China in configuration of Neoproterozoic supercontinent

ConfigurationandevolutionofNeoproterozoicsu-percontinentandthepositionofSouthChinawithinithavebeenveryimportanttargetsinearthsciencesconcerningmanyforefronttopicsofgeneralinterest.InthecommonreconstructionofthesupercontinentRodinia,SouthChinawaslocatedbetweenAustraliaandLaurentia,andthusliesinthecenterofthesupercontinentandsoutheastofAus-tralia[1].Accordingtothenewpaleomagneticandgeo-chronologicaldataforthe~800MaXiaofengdykeinYi-changaswellasexistingdata,Lietal.[2]suggestthatRodiniawouldp…     

Zircon U-Pb SHRIMP dating for the volcanic rocks of the Xiong’er Group: Constraints on the initial formation age of the cover of the North China Craton

The volcanic rocks of the Xiong‘er Group occur widely in the southern part of the North China Craton, which mark the beginning of the cover in the southern part of the North China Craton. The age of the volcanic rocks is thus crucial to understand the tectonic regime and evolutionary history of the North China Craton in the Proterozoic age. Zircons from five volcanic rocks and intrusions were dated by U-Pb SHRIMP method. The results indicate that the Xiong‘er Group formed in 1.80--1.75 Ga of Paleo-Proterozoic. Since the Xiong‘er Group formed earlier than the Changcheng System, the earliest rocks in the Changcheng System is therefore assumed to be formed in 1.75 Ga. A thermal-tectonic event of ca. 1.84 Ga is indicated by new zircon U-Pb SHRIMP ages in the southern part of the North China Craton. The volcanic rocks of the Xiong‘er Group thus represent the initial magmatism of the Paleo-Proterozoic breakup of the North China Craton. Numerous inherited zircons in the volcanic rocks mainly formed in ～2.20 Ga, indicating that the source magma of the volcanic rocks may be derived from the ～2.20 Ga crust, or from a mantle magma with significant contamination of the ～2.20 Ga crust.     

黑龙江富饶组上段凝灰岩的SHRIMP锆石U-Pb年龄:一个最接近白垩系/第三系界线的年龄

白垩系和第三系(K/T)界线时期发生了显生宙最后一次大规模的生物绝灭和劫后复苏．自Alvarez等人根据UT界线的Ir异常提出生物大绝灭的小行星撞击假说后,K/T界线的精确时代、重大地质事件和生物大灭绝及其内在联系一直受到国际学术界的极大关注．K／T界限时期(约65Ma)的冲击石英和微玻球粒的广泛分布以及在墨西哥尤卡坦半岛发现同时代的Chicxulub陨石坑,使得撞击说得到了学术界越来越广泛的赞同．然而,另一些研究人员则认为由地幔柱引发的大规模火山岩喷发、地幔去气,     

东北地区新生代侵入体的锆石激光探针U-Pb年龄测定与稀土元素成分分析

利用LA-ICPMS锆石U-Pb原位定年方法, 在不同斑束下对吉林省南部永胜霓霞正长岩获得的年龄与SHRIMP年龄(31 Ma)在准确度和精度上均相当. 该年龄也与采自辽东半岛的饮马湾山辉长岩体的年龄在误差范围内基本相同, 代表了我国东北乃至整个东部地区出露的最年轻侵入体, 指示了渐新世幔源岩浆底侵作用以及该区自30 Ma以来的显著地壳抬升与剥蚀. 同时, 永胜霓霞正长岩的锆石具有十分高的轻稀土元素含量和平坦的稀土元素配分型式, 这种异常的稀土元素配分型式在已发表的文献中尚未见报道, 属于一种新的锆石REE配分型式.     

某些锆石的裂变径迹年龄测定

沉积盆地中个别碎屑锆石颗粒通常能提供有价值的沉积物来源的信息。因此锆石的裂变径迹年龄测定广泛开展用以研究沉积盆地中矿物来源及其热历史。 目前已有几种较好的显示锆石中自裂变径迹的方法出现。本文报道了取自不同地区的锆石样品用不同的蚀刻程序得到的结果。根据我们的经验,我们认为蚀刻程序的选择对分析实验的成功是至关重要的,因为不同来源的锆石的蚀刻行为有很大差异。     

改进的裂变径迹定年锆石蚀刻技术

尽管用化学方法揭示锆石中裂变径迹比其他一些矿物困难得多,但锆石用于裂变径迹定年有许多优点,因此人们一直在努力发展和改进锆石的蚀刻方法。自1964年以来先后有H_3PO_4,375—500℃,100 mol/L NaOH,220℃,H_2SO_4+HF,150—180℃和NaOH     

单颗粒锆石的20 μm小斑束原位微区LA-ICP-MS U-Pb年龄和微量元素的同时测定

利用193nm LA-ICP-MS在20um小斑束条件下对3个国际标准锆石样品和一个实验室内部的标准锆石样品进行了U-Pb年龄和20个微量元素的同时测定．测定结果显示，91500，GJ1和TEMORA1（TEM）三个国际标准锆石样品的^206Pb/^238U加权平均年龄分别为（1064．4±4．8）Ma（2σ，n=15），（603．2±2．4）Ma（2σ，n=15）和（418．2±2．4）Ma（2σ，n=11），其分析的单点相对偏差（2σ）均小于2．2％，加权平均年龄的相对偏差（2σ）均小于0．6％．这些年龄测定值与推荐值之间在误差范围内完全一致．一个实验室内部标准锆石样品SK10-2（来自辽东地区细粒辉长岩）的^206Pb/^228U加权平均年龄为（31．42±0．25）Ma（2σ，n=16），其单点相对偏差（2σ）为2．4％-5．7％，加权平均年龄的相对偏差（2σ）为0．80％，与Yuan等测定结果一致．利用相同的仪器测试条件对NIST612和NIST614中微量元素进行了测定，测定值与推荐值在误差范围内完全一致．在年龄测定的同时，采用NIST610作外标，对微量元素分布不均匀的91500和GJ1锆石中的微量元素进行了分析，91500的测定值基本落在文献提供的元素含量变化范围之内，GJ1锆石中Pb，Th和U含量的测定值也落在TIMS测定值之内．4个锆石样品平滑性的稀土元素球粒陨石标准化曲线表明，所获得的稀土元素之间的相对含量也是准确的．这些分析表明，本次研究所建立的LA—ICP—MS分析方法，在20岬激光斑束条件下，不仅可准确测定锆石的U-Pb年龄，而且可以同时较准确的获得锆石的微量元素组成．