Paleoproterozoic mafic dyke from Kongling terrain in the Yangtze Craton and its implication  

作　　者：PENG Min WU YuanBao WANG Jing JIAO WenFang LIU XiaoChi YANG SaiHong 

机构地区：[1]State Key Laboratory of Geological Processes and Mineral Resources, Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China [2]State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an 710069, China

出　　处：《Chinese Science Bulletin》2009年第6期1098-1104,共7页

基　　金：Supported by National Natural Science Foundation of China (Grant Nos. 40772042, 90714010 and 40521001);the Ministry of Education of China (Grant Nos. IRT0441, B07039 and NCET-06-0659);Foundation of the State Key Laboratory of Continental Dynamics, Northwest University

摘　　要：Mafic dyke is a sign of regional extension, and thus has important tectonic significance. A great amount of mafic dykes occur in the Kongling terrain of the Yangtze Craton, which have great bearing on the early evolution of the Yangtze Craton. Their ages, however, have not been well constrained. In this paper we report an integrated study of zircon U-Pb age and Hf isotope compositions for a mafic dyke in the Kongling terrain. The zircons yielded a weighted mean 207Pb/206Pb age of 1852±11Ma, which represents its intrusion age. They have εHf(t) values of -6.3 to 0.5, with a weighted mean of -3.06±0.88, suggesting that the mafic dyke came from metasomatic mantle. The results indicate that the Yangtze Block had transformed into post-collisional extensional regime at ca. 1850 Ma. In the same period, the Yangtze Craton shows enough rigidity to produce brittle rupture, and thus has the characteristics of a craton.Mafic dyke is a sign of regional extension, and thus has important tectonic significance. A great amount of mafic dykes occur in the Kongling terrain of the Yangtze Craton, which have great bearing on the early evolution of the Yangtze Craton. Their ages, however, have not been well constrained. In this paper we report an integrated study of zircon U-Pb age and Hf isotope compositions for a mafic dyke in the Kongling terrain. The zircons yielded a weighted mean ^207Pb/^206Pb age of 1852±11Ma, which represents its intrusion age. They have εHf（t） values of -6.3 to 0.5, with a weighted mean of -3.06±0.88, suggesting that the mafic dyke came from metasomatic mantle. The results indicate that the Yangtze Block had transformed into post-collisional extensional regime at ca. 1850 Ma. In the same period, the Yangtze Craton shows enough rigidity to produce brittle rupture, and thus has the characteristics of a craton.

关 键 词：扬子克拉通 镁铁质 古地形 岩墙 加权平均 同位素组成 构造意义 早期演化 

分 类 号：P597[天文地球—地球化学] P313.2[天文地球—地质学]