Neoproterozoic tectonic evolution of the northwestern margin of the Yangtze Block (southwestern China): Evidence from sandstone geochemistry and detrital zircon U-Pb ages of the Hengdan Group
Neoproterozoic tectonic evolution of the northwestern margin of the Yangtze Block (southwestern China): Evidence from sandstone geochemistry and detrital zircon U-Pb ages of the Hengdan Group
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扬子地块西北缘新元古代构造演化：来自横丹群砂岩地球化学和碎屑锆石U-Pb年龄的证据
DOI：
10.1016/j.precamres.2020.105737
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发表时间：
2020-07
影响因子：
3.8
通讯作者：
Li Xiaobing
中科院分区：
文献类型：
--
作者：
Gao Feng;Pei Xianzhi;Li Ruibao;Li Zuochen;Pei Lei;Chen Youxin;Wang Meng;Zhao Shaowei;Liu Chengjun;Li Xiaobing
碧口地体西北部的横丹群保存了扬子地块西北缘新元古代早、中期构造演化的沉积档案，但其沉积时代、物源和构造环境仍存在争议。本文报道了横丹群砂岩的地球化学和年代学研究。研究表明，横丹群砂岩经历了较低程度的化学风化和沉积再循环作用，其物源主要为酸性-中性火成岩。此外，它们的元素含量（即，La、Ce、Th和REE）和比率（即，LaN/YbN和Eu/Eu~*）与活动大陆边缘环境沉积物具有可比性。所有样本产生相似的年龄分布，具有主导的年龄范围约为。850~720 Ma。结合这些年龄碎屑锆石以角状-次角状为主的形态和明显的振荡或宽环带内部结构，表明横丹群的源区应是新元古代早中期的岩浆岩。此外，横丹群砂岩中最年轻的一组碎屑锆石U-Pb年龄表明，该群沉积的开始和结束时间晚于约1000年。第741章我和你722 Ma，分别。结合前人的工作，横丹群最有可能是在约1000年左右沉积的。741~717Ma，形成于燕山期西北缘的弧前盆地中，物源可能来自附近的酸性-中性火成岩。进一步支持了扬子地台西北缘在新元古代早中期（约1000年）应是一个长期的活动大陆边缘环境。835~717Ma），华南地块应位于Rodinia超大陆的相对外围位置。
The Hengdan Group in the northwestern part of the Bikou Terrane preserves sedimentary archives for the debated early to middle Neoproterozoic tectonic evolution of the northwestern margin of the Yangtze Block (YB), while its depositional age, provenance and tectonic setting remain controversial. This research has reported the geochemical and geochronological studies on the sandstones in the Hengdan Group. Our work indicates that the sandstones in the Hengdan Group experienced low degree of chemical weathering and sedimentary recycling, and are mainly sourced from acidic to intermediate igneous rocks. In addition, their elemental contents (i.e., La, Ce, Th and ΣREE) and ratios (i.e., LaN/YbNand Eu/Eu*) are comparable to those deposited in an active continental margin setting. All samples yield similar age distribution, having a dominated age range at ca. 850 to 720 Ma. Together with the dominantly angular to subangular morphology and clear oscillatory or broad zoning internal structure of these aged detrital zircons, indicating that the Hengdan Group should be proximally sourced from the early to middle Neoproterozoic igneous rocks. In addition, the youngest group of detrital zircon U-Pb ages of the sandstones in the Hengdan Group suggest that the onset and ending of the deposition of this group is later than ca. 741 Ma and ca. 722 Ma, respectively. Combining with previous work, the Hengdan Group was most likely deposited during ca. 741 to 717 Ma in a forearc basin setting at the northwestern margin of the YB, and with its primary provenance probably from nearby acidic to intermediate igneous rocks. In addition, all these above further supports that the northwestern margin of the YB should be a long-lived active continental margin setting during early to middle Neoproterozoic (ca. 835 to 717 Ma) and, the South China Block should be located at the relative peripheral location of the Rodinia supercontinent.
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影响因子：
3
作者：
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