论文部分内容阅读
本文报道在庐山筲箕洼组中获得细碧岩SHIRMP锆石U-Pb年龄(840±6)Ma,MSWD=1.3,流纹岩锆石U-Pb年龄(833±4)Ma,MSWD=1.4,和流纹岩锆石U-Pb年龄(831±3)Ma,对应的MSWD=1.47。而在星子群流纹岩中获得206Pb/238U年龄为(825±5)Ma,对应的MSWD=0.46。笔者依据上述精确锆石年龄,首次提出将筲箕洼组明确定位于星子岩群之下。本文结合“江南造山带”锆石U-Pb年龄:东部变质基底的双桥山群,西部变质基底梵净山群和似盖层下江群以及中部变质基底冷家溪群和似盖层板溪群的锆石SHRIMP U-Pb年龄,将筲箕洼组定位于“武陵运动”之下的新元古代地层。依据星子岩群年龄数据,首次将星子岩群明确定位于筲箕洼组之上与双桥山群为同期的深变质岩。该年龄对限定区域地层对比和构造演化都有着重要意义。上述锆石U-Pb年龄标示了赣西北地区同样存在820 Ma界面上下的新元古代地层,为江南古陆变质地层的对比提供了新的年代学数据。
This paper reports the SHIRMP zircon U-Pb age (840 ± 6) Ma, MSWD = 1.3, zircon U-Pb age of rhyolites (833 ± 4) Ma and MSWD = 1.4 from Shau Kewa Formation in Lushan, And the rhyolite zircon U-Pb age (831 ± 3) Ma, corresponding to MSWD = 1.47. However, 206Pb / 238U ages of (825 ± 5) Ma were obtained in the asteroid rhyolite, corresponding to MSWD = 0.46. Based on the above accurate zircon ages, the author first proposed to locate Shau Kewa Formation under the Xingziyan Group. In this paper, the “Jiangnan orogenic belt” zircon zircon U-Pb age: the eastern metamorphic basement Shuangqiaoshan group, the western metamorphic basement Fanjingshan group and under the caprock Jiangqu group and the central metamorphic base Lengjiaxi group and cover like The zircon SHRIMP U-Pb age of the laminatrix group locates the Shau Kewa Formation in the Neoproterozoic under the Wuling movement. Based on the age data of the Xingzi Group, the Xingzi Group is located for the first time in the deep metamorphic rock over Shakuiwa Formation and Shuangqiao Group. This age is of great significance to stratigraphic contrast and tectonic evolution in a limited area. The U-Pb zircon ages above indicate the existence of the Neoproterozoic strata above and below the 820 Ma interface in the northwestern Jiangxi Province, providing new geochronological data for the comparison of the metamorphic strata in the Jiangnan Old Paleozoic.