Revealing inherited Precambrian crustal structure of the Vaupés Arch in the Colombian Amazonian Craton using teleseismic receiver functions and gravity spectral analysis

Abstract

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.