This paper reports the results of secondary ion mass spectrometry （SIMS） U-Pb dating of rutile within eclogitic xenoliths from the Early Cretaceous adakitic rocks in the Xuzhou-Huaibei area of China and discusses th...This paper reports the results of secondary ion mass spectrometry （SIMS） U-Pb dating of rutile within eclogitic xenoliths from the Early Cretaceous adakitic rocks in the Xuzhou-Huaibei area of China and discusses the geological significance of these new dates. The dating of rutile from pargasite-bearing eclogite and garnet clinopyroxenite （retrograde eclogite） yielded ages of 209 ± 25 and 132 ± 7 Ma, respectively. The former is consistent with the timing of the first stage of exhumation of the Dabie-Sulu orogenic belt and provides evidence of crustal thickening within the southeastern margin of the North China Cra- ton during the early Mesozoic, related to subduction and collision between the Yangtze and North China cratons. The latter age is similar to the timing of emplacement of the hosting intrusion and indicates that the rutile U-Pb system was triggered after uplifting by the intrusion of the hosting magmas. It implies that garnet clinopyroxenite was previously at the depth where the temperature was above the futile U-Pb closure temperature.展开更多
基金supported by National Natural Science Foundation of China(Grant No.41222023)National Basic Research Program of China(Grant No.2015CB856101)
文摘This paper reports the results of secondary ion mass spectrometry （SIMS） U-Pb dating of rutile within eclogitic xenoliths from the Early Cretaceous adakitic rocks in the Xuzhou-Huaibei area of China and discusses the geological significance of these new dates. The dating of rutile from pargasite-bearing eclogite and garnet clinopyroxenite （retrograde eclogite） yielded ages of 209 ± 25 and 132 ± 7 Ma, respectively. The former is consistent with the timing of the first stage of exhumation of the Dabie-Sulu orogenic belt and provides evidence of crustal thickening within the southeastern margin of the North China Cra- ton during the early Mesozoic, related to subduction and collision between the Yangtze and North China cratons. The latter age is similar to the timing of emplacement of the hosting intrusion and indicates that the rutile U-Pb system was triggered after uplifting by the intrusion of the hosting magmas. It implies that garnet clinopyroxenite was previously at the depth where the temperature was above the futile U-Pb closure temperature.
