The late- to post-collisional stage in orogenic systems is characterized by the coeval existence of bimodal potassic to ultrapotassic magmatic activity related to partial melting of an enriched lithospheric mantle together with crustal derived melts. In this paper, we present new whole rock geochemical analyses combined with zircon and titanite UPb and zircon Hf isotopic data from potassic to ultrapotassic rocks from six plutons that occur within the Archean Itacambira-Monte Azul block (BIMA), to discuss their petrogenesis and the tectonic implications for the São Francisco paleocontinent. The new UPb ages range from ca. 2.06 Ga to 1.98 Ga and reveal long-lasting potassic magmatism within the BIMA, which is within the late- to- post-collisional stage of the São Francisco paleocontinent evolution. The ultrapotassic rocks are compatible with a fluid-related metasomatized mantle source enriched by previous subduction events, whereas the potassic rocks are bimodal and have a transitional shoshonitic to A-type affinity. These rocks have a hybrid nature, possible related to the mixing between the mafic potassic/ultrapotassic rocks and high temperature crustal melts of the Archean continental crust. Our results also show an increase of within-plate signature towards the younger potassic magmas. The participation of an important Archean crustal component in the genesis of these rocks is highlighted by the common and occasionally abundant occurrence of Archean inherited zircons. The Hf isotopic record shows that most of the zircon inheritance has dominantly subchondritic ε_Hf(t) values, which fits a crustal reworking derivation from a similar Eo- to Paleoarchean precursor crust. However, the presence of juvenile 2.36 Ga zircon inheritance in an ultrapotassic sample reveal the existence of a hidden reservoir that is somewhat similar to the described for the Mineiro Belt in southern São Francisco paleocontinent.

造山系统中的碰撞后期至碰撞后阶段的特征是，同时存在与富集岩石圈地幔部分熔融和地壳衍生熔体有关的双峰钾盐至超钾盐岩浆活动。在本文中，我们介绍了新的全岩石地球化学分析，并结合了来自太古代Itacambira-Monte Azul区块（BIMA）内6个岩体的钾盐至超钾盐岩石的锆石和钛铁矿U Pb和锆石Hf同位素数据，讨论了它们的成因和对圣弗朗西斯科古大陆的构造意义。新U铅的年龄范围从大约 从2.06 Ga到1.98 Ga并显示出BIMA内的钾盐岩浆作用持久，该岩浆作用属于圣弗朗西斯科古大陆演化的后期至碰撞后阶段。超钾质岩与以前俯冲作用富集的与流体有关的交代地幔源相容，而钾质岩是双峰的，具有过渡的生铁质至A型亲和力。这些岩石具有混合性质，可能与镁铁质钾质/超钾质岩石与太古代陆壳的高温地壳熔体之间的混合有关。我们的研究结果还表明，板内特征对年轻的钾质岩浆的作用增加。太古代遗留下来的锆石的共同且偶尔的大量出现，突显了重要的太古宙地壳成分在这些岩石的成因中的参与。f同位素记录表明，大多数锆石遗传都以软骨下为主ε_的Hf（吨）值，其适合从类似的EO-到古太古代前体地壳地壳返工推导。但是，在超钾盐样品中存在2.36 Ga锆石的遗传物质表明存在一个隐藏的储集层，该储集层与南圣弗朗西斯科古大陆南部的Mineiro带描述的储集层有些相似。