Post-collisional reversely zoned plutons occurring in the Araçuaí belt frequently show basic cores enveloped by felsic rocks, with intense magma mingling/mixing features. The Venda Nova (VN) pluton presents, in addition to its mafic core composed of gabbronorites surrounded by syenomonzonites, a narrow ring of charnockite and norite. The VN is considered as a marker of the last magmatic phases of the Araçuaí orogenic collapse and bears one of the few high-quality Cambrian paleomagnetic data for the West Gondwana, but no geochronological data is yet available for it. In this paper, we report new in-situ U-Pb geochronological data (SHRIMP II) for the syenomonzonite, gabbro and charnockite of the Venda Nova pluton. These data are discussed and compared to the geochemical and geochronological data available for the post-collisional magmatic rocks of the Araçuaí orogen. The concordant ages of the syenomonzonite (496.9 ± 4.2 Ma, MSWD = 0.0019, n = 14) and gabbro (500.6 ± 3.7 Ma, MSWD = 0.0290, n = 14) are likely the crystallization age of the main plutonic body and corroborate the previous interpretation of paleomagnetic data. In contrast, two age groups were identified for the charnockite: Group I (n = 14, 624.0 ± 3.1 Ma, MSWD = 0.116), which includes zircon borders and rims without evidence of border reaction, and Group II (n = 6, 483.7 ± 7.4 Ma, MSWD = 0.0003) from zircon grains with luminous rims and older cores. Since the Venda Nova charnockite has (i) a distinct geochemical signature compared to other post-collisional charnockite bodies found in the same region, (ii) higher magnetic anisotropy degrees compared to other border units of the same intrusion, and (iii) marked sub-solidus deformation features, the Group I ages are suggested as the crystallization age of these rocks, while Group II ages would be better interpreted as a resetting due to the thermal influence of the syenomonzonite and gabbro intrusions. This implies that the VN is a composite magmatic complex with contributions of magmas from the pre-collisional magmatic arc and from the post-collisional melts originated in the crust and mantle across the Araçuaí lithosphere during orogen collapse.

发生在阿拉苏伊带的碰撞后反向成带岩体经常显示出被长英质岩石包裹的基本岩心，具有强烈的岩浆混合/混合特征。Venda Nova (VN) 岩体除了由被正长二长岩包围的辉长岩组成的镁铁质核心外，还呈现出一个由 charnockite 和 norite 组成的狭窄环。VN被认为是Araçuaí造山崩塌最后岩浆阶段的标志，是西冈瓦纳地区为数不多的高质量寒武纪古地磁数据之一，但尚无可用的年代学数据。在本文中，我们报告了 Venda Nova 岩体的正长二长岩、辉长岩和石英岩的新原位 U-Pb 年代学数据 (SHRIMP II)。讨论了这些数据，并将其与可用于 Araçuaí 造山带碰撞后岩浆岩的地球化学和地质年代学数据进行了比较。正长二长岩（496.9 ± 4.2 Ma，MSWD = 0.0019，n = 14）和辉长岩（500.6 ± 3.7 Ma，MSWD = 0.0290，n = 14）的一致年龄可能是主深成体的结晶年龄，并证实了先前的古地磁数据的解释。相比之下，为 charnockite 确定了两个年龄组：第一组 (n = 14, 624.0 ± 3.1 Ma, MSWD = 0.116)，其中包括没有边缘反应证据的锆石边界和边缘，以及来自具有发光边缘和较旧核心的锆石颗粒的 II 组 (n = 6, 483.7 ± 7.4 Ma, MSWD = 0.0003)。由于 Venda Nova 石英岩具有 (i) 与在同一地区发现的其他碰撞后石英岩体相比具有明显的地球化学特征，(ii)与同一侵入体的其他边界单元相比的磁各向异性程度，以及 (iii) 显着的亚固相线变形特征，建议 I 组年龄作为这些岩石的结晶年龄，而 II 组年龄将更好地解释为重置，因为正长二长岩和辉长岩侵入体的热影响。这意味着 VN 是一个复合岩浆复合体，岩浆来自碰撞前岩浆弧和碰撞后熔体，这些熔体起源于 Araçuaí 岩石圈的地壳和地幔，在造山带塌陷期间。