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Sedimentary Facies, Provenance and Geochronology of the Heshangzhen Group: Implications for the Tectonic Evolution of the Eastern Jiangnan Orogen, South China
Acta Geologica Sinica-English Edition ( IF 3.5 ) Pub Date : 2020-08-30 , DOI: 10.1111/1755-6724.14570 Zhou Xiaohua 1 , Hu Xiumian 2 , Jiang Ren 1 , Gao Tianshan 1 , Ma Xue 1 , Xing Guangfu 3 , Sun Gaoyuan 4 , Shu Xujie 1 , Zhao Xilin 1
Acta Geologica Sinica-English Edition ( IF 3.5 ) Pub Date : 2020-08-30 , DOI: 10.1111/1755-6724.14570 Zhou Xiaohua 1 , Hu Xiumian 2 , Jiang Ren 1 , Gao Tianshan 1 , Ma Xue 1 , Xing Guangfu 3 , Sun Gaoyuan 4 , Shu Xujie 1 , Zhao Xilin 1
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The Neoproterozoic Jiangnan orogen plays an important role in the study of the Precambrian tectonic evolution of South China. The tectonic nature of the Neoproterozoic sedimentary basins is still controversial, due to poor understanding of the sedimentary sequences and the lack of geochronological data. Here, we present sedimentological, provenance and geochronological data from the Heshangzhen Group in the eastern Jiangnan orogen. Sedimentological analysis shows that the Luojiamen Formation was deposited in a submarine fan, and the overlying Hongchicun Formation was deposited in front of a fan delta. The youngest detrital zircons constrain the lower Luojiamen and Hongchicun formations with ages of 827.3 ± 8.4 Ma and 825 ± 12 Ma, respectively. The sandstones of the Luojiamen Formation are characterized by a large number of intermediate to felsic volcanic grains, suggesting a volcanic arc source. In contrast, quartz and sedimentary lithic grains increase in the Hongchicun Formation, showing a new input from a collisional orogenic source. Detrital zircon from six sandstone samples in the Luojiamen and Hongchicun formations yield similar age spectra of 930–820 Ma with a peak at ca. 845–860 Ma, with one main cluster at 930–820 Ma. Detrital zircons of 930–845 Ma show a positive value of ∊Hf (t) (+2.4 to +11, mean +7.6), which is similar to the volcanic arc of the nearby Shuangxiwu Group. There are a minor group of zircons with U‐Pb ages ranging from 820 Ma to 845 Ma from the middle part of the Luojiamen Formation and Hongchicun Formation, with ∊Hf (t) values between –20 to +2.4, which are consistent with the characteristics of the Shuangqiaoshan Group. within light of the bidirectional paleocurrents in the Luojiamen Formation, it is speculated that the zircons of 820–845 Ma were recycled from the Shuangqiaoshan Group, which is derived from a continental arc to the northwest. Our data suggests that the Luojiamen Formation was formed in an inter‐arc basin, while the Hongchicun Formation was formed in an accretionary wedge‐top basin. When juxtaposed with the conglomeratic characteristics at the bottom of the Luojiamen Formation, it is believed that the unconformity represented by the ‘Shen Gong Movement’ reflects the rapid erosion and accumulation process of island arc volcanic material. The disconformity between the Luojiamen and Hongchicun formations is the imprint of transition from inter‐arc basin to accretionary wedge‐top basin, which represents the collision between the Shuangxiwu arc and the Yangtze Plate.
中文翻译：
和尚镇群的沉积相，物源和年代学：对江南造山带东部构造演化的启示
新元古代江南造山带在华南前寒武纪构造演化研究中起着重要作用。新元古代沉积盆地的构造性质仍存在争议，这是由于对沉积层序了解不足以及缺乏年代学数据。在这里，我们介绍了江南造山带东部赫山镇组的沉积学，物源和年代学数据。沉积学分析表明，oji家门组沉积在海底扇形体中，上覆的洪池村组沉积在扇形体三角洲前。最年轻的碎屑锆石分别约束了较低的罗家门组和洪池村组，年龄分别为827.3±8.4 Ma和825±12 Ma。oji家门组砂岩的特征是大量的中长生质火山岩，暗示了火山弧源。相比之下，洪池村组石英和沉积岩性颗粒增加，表明来自碰撞造山源的新输入。骆家门组和洪池村组六个砂岩样品中的碎屑锆石的年龄谱相似，在930-820 Ma左右，峰值在。845-860 Ma，其中一个主星团在930-820 Ma。930–845 Ma碎屑锆石显示正值 骆家门组和洪池村组六个砂岩样品中的碎屑锆石的年龄谱相似，在930-820 Ma左右，峰值在。845-860 Ma，其中一个主星团在930-820 Ma。930–845 Ma碎屑锆石显示正值 骆家门组和洪池村组六个砂岩样品中的碎屑锆石的年龄谱相似，在930-820 Ma左右，峰值在。845-860 Ma，其中一个主星团在930-820 Ma。930–845 Ma碎屑锆石显示正值∊ Hf（t）（+2.4至+11，均值+7.6），类似于附近的双溪坞群的火山弧。在Lu家门组和洪村村组中部有一小群U-Pb年龄为820 Ma至845 Ma的锆石，∊ Hf（t）介于–20到+2.4之间的值，这与双桥山群的特征一致。根据the家门组的双向古流，推测820－845 Ma的锆石是从大陆桥向西北方向的双桥山群中回收的。我们的数据表明，oji家门组形成于一个弧形盆地中，而洪池村组则形成于一个增生的楔顶盆地中。当与the家门组底部的砾岩特征并列时，可以认为以“神功运动”为代表的不整合面反映了岛弧火山岩材料的快速侵蚀和聚集过程。
更新日期：2020-08-30
中文翻译：
和尚镇群的沉积相，物源和年代学：对江南造山带东部构造演化的启示
新元古代江南造山带在华南前寒武纪构造演化研究中起着重要作用。新元古代沉积盆地的构造性质仍存在争议，这是由于对沉积层序了解不足以及缺乏年代学数据。在这里，我们介绍了江南造山带东部赫山镇组的沉积学，物源和年代学数据。沉积学分析表明，oji家门组沉积在海底扇形体中，上覆的洪池村组沉积在扇形体三角洲前。最年轻的碎屑锆石分别约束了较低的罗家门组和洪池村组，年龄分别为827.3±8.4 Ma和825±12 Ma。oji家门组砂岩的特征是大量的中长生质火山岩，暗示了火山弧源。相比之下，洪池村组石英和沉积岩性颗粒增加，表明来自碰撞造山源的新输入。骆家门组和洪池村组六个砂岩样品中的碎屑锆石的年龄谱相似，在930-820 Ma左右，峰值在。845-860 Ma，其中一个主星团在930-820 Ma。930–845 Ma碎屑锆石显示正值 骆家门组和洪池村组六个砂岩样品中的碎屑锆石的年龄谱相似，在930-820 Ma左右，峰值在。845-860 Ma，其中一个主星团在930-820 Ma。930–845 Ma碎屑锆石显示正值 骆家门组和洪池村组六个砂岩样品中的碎屑锆石的年龄谱相似，在930-820 Ma左右，峰值在。845-860 Ma，其中一个主星团在930-820 Ma。930–845 Ma碎屑锆石显示正值∊ Hf（t）（+2.4至+11，均值+7.6），类似于附近的双溪坞群的火山弧。在Lu家门组和洪村村组中部有一小群U-Pb年龄为820 Ma至845 Ma的锆石，∊ Hf（t）介于–20到+2.4之间的值，这与双桥山群的特征一致。根据the家门组的双向古流，推测820－845 Ma的锆石是从大陆桥向西北方向的双桥山群中回收的。我们的数据表明，oji家门组形成于一个弧形盆地中，而洪池村组则形成于一个增生的楔顶盆地中。当与the家门组底部的砾岩特征并列时，可以认为以“神功运动”为代表的不整合面反映了岛弧火山岩材料的快速侵蚀和聚集过程。
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