【摘 要】
：
An unusual zircon SHRIMP dating result of a granitic gneiss from the Qinglongshan eclogite-gneiss roadcut section is presented in this paper. The very peculiar
【机 构】
：
Institute of Mineral Resources,Géosciences Rennes
论文部分内容阅读
An unusual zircon SHRIMP dating result of a granitic gneiss from the Qinglongshan eclogite-gneiss roadcut section is presented in this paper. The very peculiar and complicated internal structures, as well as the very low Th/U ratios (0.01-0.08) of the zircons indicate that they were formed by metamorphic recrystallization. Strongly in contrast with previously published zircon U-Pb ages of the Dabie-Sulu UHP metamorphic rocks where protolith ages of 600-800 Ma are commonly recorded, only metamorphic age of 218+5 Ma, defined by 18 analytical spots either in rim or in core of zircons, are recorded in this granitic gneiss. This age represents the time of the complete metamorphic recrystallization overprint on primary magmatic zircons. The recrystallization was derived by the UHP metamorphism,and was strengthened by the early stage of retrograde metamorphic fluid activity.
其他文献
The interdecadal variation of Pacific thermocline represented by depth anomalies of 25 σθ isopycnal surface calculated from SODA data set is analyzed. The cli
The watershed flow concentration scheme in the distributed hydrology-soil- vegetation model (DHSVM) is coupled with the mesoscale atmospheric model MM5 version
This paper reports Re-Os and Nd isotopes of black shales at the bottom of Lower Cambrian from the northern Tarim Basin and traces source materials of the black
There are many welding fixture layout design problems of flexible parts in body-in-white assembly process, which directly cause body assemble variation.The fixt
In order to determine the age of the sedimentary hiatus and its geological significance, a study of the calcareous nannofossil biostratigraphy was carried out.
Control of aggregation, by lowering temperature and protein concentrations, can enhance the extent of successful refolding. The low temperature has been used in
K-Ar ages of the Mesozoic (92-100 Ma) Fuxin alkalic basalts (western Liaoning Province) and the Tertiary (23-45 Ma) Pingquan alkalic basalts (eastern Hebei Prov
In the Linxia Basin on the northeast margin of the Tibetan Plateau, the Cenozoic strata are very thick and well exposed. Abundant mammalian fossils are discover
Dike swarms are generally ascribed to intrusion of mantle-source magma result from extension. Basic dike swarms around the Shanxi-Hebei-Inner Mogolia borders in