Reimold W. U. auteur aut IRD Ferriere L. auteur aut IRD Crosta A. P. auteur aut IRD Vasconcelos M. A. R. auteur aut IRD Gottwald M. auteur aut IRD da Silva Borges M. auteur aut IRD de Almeida T. I. R. auteur aut IRD Pereira F. L. auteur aut IRD Goes A. M. auteur aut IRD Hauser N. auteur aut IRD Jessell M. auteur aut IRD Baratoux David auteur aut IRD text journalArticle eng text/pdf born digital access The Nova Colinas structure is an approximately 7 km wide, nearly circular feature centered at 07 degrees 09 ' 33 ' S/46 degrees 06 ' 30 ' W in Nova Colinas municipality in southwestern Maranhao State, Brazil. The area has been investigated for 40 yr and it has been suggested repeatedly that the structure could be of impact origin-without proof having been furnished. Magnetic anomaly maps depict the structure clearly with a strong, positive magnetic anomaly over the apparent rim zone. The central area is characterized by significant positive K and Th radiometric anomalies. Fieldwork showed that the structure has annular features along the outside and some prominent, structurally dissected hills in the interior. Thirty-three arenite samples were collected for petrographic analysis, mostly from within the structure. Microdeformation, in the form of cataclasis; concussion fractures related to compaction, and presence of planar fractures, feather features, and planar deformation features in quartz are reported. Three samples with a multitude of quartz grains with these microdeformations were analyzed by universal stage to determine the crystallographic orientations of planar fractures and planar deformation features. The results provide robust evidence that these microdeformation features represent shock metamorphism, with low (approximately 5-10 GPa) to moderate (10-16 and 10-20 GPa) shock levels. Thus, the Nova Colinas structure is now confirmed as a bona fide meteorite impact structure. The structure is moderately eroded, as shown by the absence of stronger shock deformation. The still limited available structural geological field evidence, paired with remote sensing and geophysical data, indicates that the innermost part of the structure may have a sizable remnant of a central uplift. The Nova Colinas impact age is only poorly constrained from stratigraphic inference to an upper limit of about 200-250 Ma. specialized BRESIL 064 [Early access] [23 ] 2022 1086-9379 https://www.documentation.ird.fr/hor/fdi:010085336 10.1111/maps.13833 1086-9379 [F B010085336] https://www.documentation.ird.fr/hor/fdi:010085336 https://www.documentation.ird.fr/intranet/publi/2022-09/010085336.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2022-09-02 2025-02-24 fdi:010085336 fre