A systematic Sm-Nd isotopic study is reported for Paleoproterozoic to Late Paleozoic strata from the Dongchuan area in the southwestern Yangtze Block. The results, combined with the available detrital zircon U-Pb ages and Hf isotope data, constrain the provenances of these sedimentary rocks and further identify three important tectono-magmatic activities. Most of the Paleo-Mesoproterozoic samples (Dongchuan Group) display a wide T_DM2 range of 1.92–2.52 Ga with corresponding ε_Nd(t) values of +4.0 to −3.5, suggesting Paleoproterozoic-dominated provenances mixed with mantle-derived materials. This corresponds to the ~1.7–1.5 Ga mafic magmatic activities commonly occurred in the southwestern Yangtze Block, which are related to the early breakup of the Columbia supercontinent. The obvious vale of T_DM2 and apex of ε_Nd(t) occurred in the Neoproterozoic strata (~0.8 Ga) of the southwestern margin over the whole Yangtze Block. This is consistent with the widely recognized mantle-derived magmatism around the Yangtze Block related to the breakup of Rodinia. However, the decreases in Nd model ages are different among various regions, indicating that the Neoproterozoic mantle inputs are more profound in the southwestern and central Yangtze Block than the southeastern Yangtze and the Jiangnan orogenic belt. The late Ediacaran to early Cambrian strata from the southwestern Yangtze exhibit a decrease in T_DM2 (from 2.00 to 1.67 Ga) and increase in ε_Nd(t) (from −9.0 to −5.2). This is in accordance with the coeval juvenile crustal materials discovered in the northwestern Yangtze, which were probably derived from the assembly of the Gondwana continent. Thus, a Gondwanan affinity is suggested for the southwestern Yangtze Block. Overall, the Nd isotopic studies of the Paleoproterozoic to Late Paleozoic sedimentary strata from the southwestern Yangtze Block identified three major episodes of magmatic activities, late Paleoproterozoic (~1.7 Ga), Neoproterozoic (~0.8 Ga) and late Neoproterozoic-early Cambrian (~0.55 Ga) in the context of Columbia, Rodinia and the subsequent Gondwana supercontinents.

扬子西南地区东川地区古元古代至晚古生代地层Sm-Nd同位素研究报道。结果与可利用的碎屑锆石U-Pb年龄和Hf同位素数据相结合，限制了这些沉积岩的出处，并进一步确定了三个重要的构造岩浆活动。大部分古中元样品（东川集团）显示一个宽的Ť _DM2 1.92-2.52 Ga中范围与对应ε_钕（吨）的值在+4.0到-3.5之间，表明古元古代占优势的物源与地幔衍生的材料混合在一起。这对应于西​​南扬子地带普遍发生的〜1.7–1.5 Ga镁铁质岩浆活动，这与哥伦比亚超大陆的早期破裂有关。明显的谷Ť _DM2和顶点的ε_钕（吨）发生在整个扬子地块西南缘的新元古代地层（〜0.8 Ga）中。这与扬子地块周围与罗迪尼亚破裂有关的地幔源岩浆作用是公认的。但是，Nd模型年龄的减少在不同地区之间是不同的，这表明扬子西南部和中部的新元古代地幔输入比扬子东南部和江南造山带更深。已故埃迪卡拉从西南扬子早寒武纪地层表现出降低Ť _DM2（2.00〜1.67 Ga）的和在增加ε_钕（吨）（从-9.0到-5.2）。这与扬子西北部发现的近代幼年地壳材料是一致的，这些材料可能来自冈瓦纳大陆的集合体。因此，建议在西南扬子地块建立冈瓦纳亲和力。总的来说，西南扬子地块的古元古代至晚古生界沉积层的Nd同位素研究确定了三个主要的岩浆活动事件，即古元古代晚期（〜1.7 Ga），新元古代（〜0.8 Ga）和新元古代晚期-早寒武世（〜0.55）。 Ga）在哥伦比亚，Rodinia和随后的冈瓦纳超大洲范围内。