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    Petrology, metallogeny and U-Pb geochronology of the Paleoproterozoic mafic-ultramafic Hamutenha intrusion, Angolan Shield
    (Elsevier BV, 2022-10-12)
    The Hamutenha intrusion (Huíla province, SW Angola) is a 3-km-long elongated magmatic body defined by a set of two intrusive units. The northern unit is formed by alternating bands of dunites and olivine gabbros, while the southern unit is composed of amphibole diorites. The Hamutenha body is hosted by the Paleoproterozoic Epupa Complex in the Angolan Shield, SW margin of the Congo Craton. A mineralogical, petrological and geochemical study of the Hamutenha intrusion has been performed. The constrained compositional features of the parental melt suggest interaction of tholeiitic magmas with a significant enrichment in Fe and Ti. Although disseminated Fe–Ni–Cu-(Co) secondary sulphides are observed, both the crustal contamination parameters and generally low bulk-rock metals contents indicate that these elements were most likely previously extracted from the parental melt. U–Pb zircon dating of amphibole diorite samples from the southern unit yields a date of 1844 ± 14 Ma. These data suggest that the emplacement of these rocks was previous to the KC emplacement and it was probably related to the Paleoproterozoic Epupa Complex magmatism.
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    Revealing inherited Precambrian crustal structure of the Vaupés Arch in the Colombian Amazonian Craton using teleseismic receiver functions and gravity spectral analysis
    (Taylor and Francis Ltd., 2026-01-01)
    Uncovering the crustal structure is essential for understanding the tectonic history of a region. However, such analysis in remote and poorly exposed areas such as the Colombian Amazonian Craton is often challenging due to limited geological and geophysical data. This research presents a new regional Moho model for the southeastern Amazonian region in Colombia, encompassing the Sub-Andean basins and part of the northwestern Amazonian Craton. We combined Moho depth estimates from gravity analysis, using a 2D radially averaged power spectrum, with those derived from receiver functions using the H-k stacking technique at five seismic stations. The resulting Moho map reveals notable crustal heterogeneities along the NW-SE trending Vaupés Arch, with depths ranging from 33 to 51 km. In the light of the limited evidence of Phanerozoic tectonic activity in the Colombian Amazonian Craton and the inconsistency between Moho depths and present-day topography as indicated by an isostatic model, we suggest that the observed Moho depth variations likely reflect a polyphase history of Precambrian contraction and extension in the NW Amazonian Craton. This history is linked to Neoproterozoic rifting during Rodinia's break-up, which led to discontinuous crustal thinning in crustal domains previously thickened by Paleo-Mesoproterozoic orogenic pulses and the compressional phases of the Putumayo Orogen. Our findings underscore the value of integrating geophysical methods to better understand the tectonic evolution of cratonic regions with sparse surface data.