SHRIMP zircon U-Pb geochronology of Indosinian granites in Hunan Province and its petrogenetic implications

The structure, magmatism and sedimentation within the South China Block (SCB) related to the Indosinian Orogeny had attracted considerable attention since De-prat[1] and Fromagat[2] proposed the “Indosinian move-ment” based on two unconformities between Pre-Norian and Pre-Rhaetian during Triassic in Vietnam. However, Indosinian tectonic evolution of the SCB has been long debated[3―6]. Some researchers believed that the compli-cated structure-magmatism-sedimentation within the SCB w…     

SHRIMP U-Pb zircon geochronology and its implications on the Xilin Gol Complex,Inner Mongolia,China

The Xilin Gol Complex was referred to the meta-morphic rocks exposed near Daqing Pasturage, east of Xilinhot, for the first time by the Hebei Geological Survey in 1958[1]. Similar metamorphic rocks have been increas-ingly identified in the Xilin Gol-Xiwuqi-Balinyouqi re-gion since then. They all are collectively grouped into the Xilin Gol Complex and considered as a part of the Bao- yintu Group (Pt1by)[1]. However, the timing of its deposi-tion and subsequent deformation and metamorphi…     

内蒙古科尔沁右翼中旗孟恩陶勒盖岩体年代学研究

对内蒙古科尔沁右翼中旗地区孟恩陶勒盖岩体进行了LA-ICP-MS锆石U-Pb同位素年代学研究.结果表明,孟恩陶勒盖岩体形成年龄为(224±1)Ma,表明该岩体是在中三叠世侵位的.结合区域地质资料和前人相关研究,推测该区中三叠世花岗岩可能是古亚洲洋闭合碰撞时岩石圈挤压机制下的产物,该结果为华北板块与西伯利亚板块碰撞时限提供了新的年代学资料.     

40Ar-39Ar and U-Pb ages of metadiorite from the East Kunlun Orogenic Belt: Evidence for Early-Paleozoic magmatic zone and excess argon in amphibole minerals

Single-grain zircon U-Pb and amphibole 40Ar-39Ar dating have been conducted on a deformed and metamorphosed diorite in the East Kunlun Orogenic Belt, which intruded into the middle Proterozoic Kuhai Group exposed in the south of Xiangride region, Dulan County, NW Qinghai Province. The zircon gives a concordant U-Pb age of (446.5±9.1) Ma. The amphibole yields Ar plateau age of (488.0±1.2) Ma and an isochronal age of (488.9±5.6) Ma. Age results of both stepwise released Ar and conventional K-Ar analysis are remarkably higher than that of zircon U-Pb, suggesting that the amphibole contains excess argon and the amphibole plateau age cannot be taken as the timing of metamorphism or deformation. The zircon age is interpreted to be crystallization age of the diorite pluton, which suggests that an Early-Paleozoic magmatic zone indeed existed in the East Kunlun Orogenic Belt stretching along the region south to the Golmud, Normuhong and Xiangride.     

Sedimentary Siloxanes: A Geochronological Study

Selected samples of sediments from cores taken in the Ala Wai Canal (south-east Oahu, Hawaii) have been analyzed for organosilicon (silicone) content. Observed levels of silicone range from just above the detection limit (≈0.01 ppm) to over 1 ppm, and vertical distribution in the sediment column generally increases upwards, with the highest silicone content in the most contemporary sediments (dated independantly( by ²¹⁰Pb and ¹³⁷Cs measurements). Further, there is clear evidence of spike events (i.e. high levels of silicone in older, buried sediments) which appear to be associated with major, documented storm events on the island os Oahu. Silicone assay was by solvent extraction, and quantitative spectrophotometric measurement at 7.95 μm. The Ala Wai Canal is an anthropogenic hydorgraphic feature on Oahu. © 1997 by John Wiley & Sons, Ltd.     

扬子板块西缘盐边群及周边岩体地质年代学新格局

扬子板块西缘的盐边群及其周边岩体,作为前寒武纪构造岩浆活动带的核心,是观察和研究新元古代大陆壳生长的重要窗口.查明这一构造岩浆活动带内地质体的产出时代及构造岩浆活动的轨迹,是揭示新元古代大陆壳产生、发展地球动力学过程的重点环节.对盐边群及周边岩体的地质年代学研究表明:(1)区内大规模的岩浆事件集中在中元古代晚期至新元古...     

40Ar/39Ar同位素体系及其在地学上的应用

40Ar/39Ar同位素体系大体经历了3个技术阶段常规 40Ar/39Ar定年技术、40Ar/39Ar分步加热定年技术和40Ar/39Ar激光显微探针定年技术.研究表明可以通过大气中40Ar/39Ar比值随时间的变化窥探地球去气作用的时间和强度;40Ar/39Ar法不仅有助于研究岩浆冷却过程和花岗岩侵位机制等岩浆动力学的历史和壳幔演化,而且对研究热液成矿年龄也是很有效方法之一;在一定的地质条件下,沉积地层时代越老,40Ar/39Ar值越高;当今40Ar/39Ar年代法已为全球环境演变研究提供了一种强有力的工具.     

Lumineszenzdatierung quartärer Sedimente

The purpose of this paper is to discuss briefly the basis, technique and efficiency of luminescence dating. Thermoluminescence and optically-stimulated luminescence are useful for dating of quaternary sediments. Contents: Sediment Dating, Thermoluminescence Dating, Thermoluminescence (TL), Dating Method, Sources of Error, Dosimetry, Dating Techniques, Optical Dating (OSL), Sediments, References.