40Ar-39Ar dating and geological implication of auriferous altered rocks from the middle-deep section of Q875 gold-quartz vein in Xiaoqinling area, Henan, China

The 40Ar-39Ar age method is employed in this work to analyze the aurif erous altered rocks from the middle-deep section of the Q875 gold-quartz vein in the Xiaoqinling area, and the results show that the main gold deposition of the Q875 occurred in ca. 128-126 Ma. As a typical gold-bearing quartz vein in this gold-rich area, the age data obtained from the Q875 also constrain on the metal logenic time of the lode gold deposits developed in the same geological settings . This geochronological study supplies new evidence for further understanding the timing of gold mineralization, the genesis of gold deposits and the geodynamic settings in Xiaoqinling area.     

冲绳海槽火山岩同位素特征及铀系组分法测年

借助多种分析方法,对采自冲绳海槽北段和中段的火山岩进行了常量元素、稀土元素、Sr-Nd同位素组成分析及铀系组分法年龄测定,在此基础上对此地区的海槽岩浆的起源、演化及岩石类型进行了研究。结果表明:(1)海槽晚更新世(大约10万年)以来有一期广泛的酸性火山喷发活动;(2)受板块俯冲的控制,此期火山活动年龄按照与琉球岛弧距离的由近到远而由新到老;(3)海槽北、中段岩浆演化过程相似,其下很可能存在有巨大的、统一的岩浆房,但与海槽南段岩浆作用差异明显,岩浆物质很可能来源于PREMA地幔源区;(4)此地区的黑色浮岩为钙碱性系列流纹岩,岩石化学组成与海槽产出的白色浮岩相似,形成年代为17.7±2.1 ka。     

Zircon SHRIMP U-Pb dating of meta-diorite from the basement of the Songliao Basin and its geological significance

Located in the east portion of the North Orogenic Belt, the Songliao Basin is bounded by the Da Hinggan Mountains in the west, the Xiao Hinggan Mountains in the north, the Zhangguangcai Range in the east, and the North China Craton (NCC) in the south (Fig…     

重庆梁天湾14号石笋沉积特征与同位素年龄

对采自重庆金佛山梁天湾洞穴的一根长290mm的14号石笋进行了高精度的定年和稳定同位素分析．在此基础上，对石笋的沉积结构、层面构造、沉积间断等特征标志进行了研究，阐述了重庆梁天湾涧石笋的沉积特征以及洞穴占滴水的动态变化．TIMS-U系测年结果表明：该石笋形成于31．9KaB．P．，结束于15．21Ka B．P．，属于末次冰期晚期的产物．石笋的沉积基本连续。没有明显的沉积间断，共分为4个旋回，沉积速率从老到新分别为65．22mm/Ka,8．37mm／Ka，97．09mm／Ka,24．39mm／Ka．     

SHRIMP U-Pb zircon geochronology of granulites at Rimana （Southern Tibet） in the central segment of Himalayan Orogen

TheCenozoicHimalayanorogenisimportantinun-derstandingcontinentaldynamicprocesses.Lowercrustal,high-grademetamorphicrockshaverecentlybeendiscov-eredinNamcheBarwaandParmir,i.e.therespectivere-gionsofeasternandwesternsyntaxisoftheorogen[1—4].Eclogitesthatunderwentgranulite-faciesmetamorphismhaverecentlybeenreportedintheCadaareatotheeastofMountEverestinthecentralsegmentoftheHimalayanorogen[5].WiththehelpofthegeologicalsurveyofDing-gyeCountyandChentangSheets(scale1︰250000),high-pressuremafic…     

释光测年的研究简史及研究现状

针对释光现象的研究，及其在地质和考古年代测定中的应用，将释光测年的研究历史划分为3个阶段：20世纪50年代末以前，释光测年研究的萌芽阶段；60年代至80年代中期，热释光测年的研究及发展阶段；80年代中期至今，光释光测年的研究及发展阶段。最后，对释光测年的研究现状进行了简单的总结，认为对释光现象产生机制的许多细节还有待深入研究，对于非线性释光生长曲线的校正及提高测年的精度，仍是测量等效剂量(De)时研究的主要问题。     

Mineralizing age of the Rushan lode gold deposit in the Jiaodong Peninsula：SHRIMP U-Pb dating on hydrothermal zircon

Knowledge of the mineralizing timing is fundamen-tal to understand the genesis of mineral deposits, and ex-act time spectrum of mineralization is essential to com-prehending the relationship among the genesis of en-dogenic hydrothermal deposits, regional tectonic-magma-tism event and the geodynamics of mineral deposits. The Jiaodong or eastern Shandong gold province islocated in the southeastern margin of the North Chinacraton, and belongs to the Mesozoic circum-Pacific oro-genic gold system…     

Timing and setting of Guanjiagou conglomerate in South Qinling and their tectonic implications

TheGuanjiagouFormationisafault-boundterranelocatedintheSouthQinlingMountains,centralChina.Theageandtectonicsettingoftheconglomerateinthisformation(Guanjiagouconglomerate,GC)havebeencontroversialsincethe1940s,withnumerousconflictinginterpretationsandcorrelationsproposedbydifferentworkers.Forexample,itwasinitiallydescribedbyYeetal.(1944)[1],whointerpretedtheGCasSinian(LatestNeo-proterozoic)tillites.However,Huang[2]regardedtheGC,plustheBikouSystem(composedoftheBikouvolcanicandtheHengdant…     

SHRIMP U-Pb zircon dating on Nyainqentanglha granite in central Lhasa block

The Nyainqentanglha granite, a batholith with an area of 1500 km^2 in the central Lhasa block, comprises mainly medium-fine-grained biotite monzonitic granite and medium-coarse-grained biotite monzonitic granite. Their contact relationship suggests that the medlum-fine-grained biotite monzonitic granite was crystallized earlier than the medium-coarse-grained monzonitic granite. A SHRIMP U-Pb dating on zircons from representative samples of the batholith shows that the crystallization age of the medium-fine-grained biotite monzonitic granite is 18.3 Ma and that of the medium-coarse-grained monzonitic granite is 11.01 Ma. The emplacement and crystallization of the Nyainqentanglha granite, the youngest granite batholith ever known inside the Lhasa block, have a close relationship with the collisional orogeny, crustal thickening, plateau uplifting,E-W crustal extension and have a dynamic genetic relationship with the crustal partial melting.     

A combined study of SHRIMP U-Pb dating, trace element and mineral inclusions on high-pressure metamorphic overgrowth zircon in eclogite from Qinglongshan in the Sulu terrane

Methods recently advanced for discrimination on the genesis of metamorphic zircon, such as analysis of mineral inclusions and trace elements, provide us powerful means to distinguish zircon overgrowth during high-pressure metamorphism. Zircons in ultrahigh-pressure eclogite from Qinglongshan in the Sulu terrane were studied by the SHRIMP U-Pb method in combining with trace element and mineral inclusion analyses. No inherited core was identified in the analyzed zircons by means of cathodoluminescence images. The occurrence of high-pressure metamorphic mineral inclusions in zircon, such as garnet, omphacite, rutile, and the flat HREE pattern in zircon indicate that the zircon formed at high-pressure metamorphic conditions. Therefore, a weighted average U-Pb age of 227.4±3.5 Ma obtained from such a kind of zircon is interpreted to represent the timing of peak nietamorphism for the Qinglongshan eclogite.