Coupling of tectonic factors and precipitation variability as a driver of Late Quaternary aggradation in Northeast Brazil

• Published in: Earth surface processes and landforms 2020-11, Vol.45 (14), p.3525-3539
• Main Authors: Fonsêca, Drielly Naamma, Barros Corrêa, Antonio Carlos, Azevêdo Cavalcanti Tavares, Bruno, Rodrigues de Lira, Daniel, Magalhães de Barros, Ana Clara, Silva Mützenberg, Demétrio
• Format: Article
• Language: English
• Subjects: Accretion; Aggradation; Borborema Plateau Piedmont; Climate; colluvium; Context; continental margin; Continental margins; Coupling; Deposition; Dismantling; Dynamics; Evolution; Fluvial deposits; Foothills; Geological time; Geomorphology; Holocene; Landforms; Landscape; luminescence OSL dating; paleoclimates; paleoenvironmental reconstruction; Passive margins; Precipitation; Precipitation variability; Quaternary; Sediment; Sediments; Tectonics; Tropical climate; Variability
• ISSN: 0197-9337; 1096-9837
• DOI: 10.1002/esp.4982

The coupling between tectonic factors and climate processes is a key element in understanding landscape evolution. However, few studies address this issue in the context of unglaciated tropical areas in passive continental margins. Thus, this research aimed to understand the origins and evolution of the geomorphological landscape in the eastern sector of Northeast Brazil along the Late Quaternary, between the Last Interstadial (Marine Isotopic State 3) and the Upper Holocene. The morphostratigraphic approach, coupled with sedimentological analyses and optically stimulated luminescence dating of sediments, showed that the depositional record stored in the landscape ranges from at least 60 000 years BP until the Upper Holocene. Depositional intervals suggest that there were moments of climatic instability followed by moments of relative geomorphological quiescence. Such active moments coincide chronologically with Heinrich and Dansgaard‐Oeschger events, which are likely linked to changes in paleo‐pluviosity that might respond to the dismantling of elluvial covers and colluvial deposition in the area. Likewise, reworking of hillslope materials led to increased deposition in the fluvial realm. In addition, such deposits might have been affected by the neotectonic complexity of the area, responsible for the creation of non‐concatenated accommodation spaces, indicating a dynamics of uplifting and subsidence of blocks typical of passive margin taphrogenic environments. Therefore, the formative processes that led to the Late Quaternary deposition of sediments in a platform margin context reflect a coupling between tectonic and climatic factors. The former, driven by precipitation variability on a regional scale, triggered fluvial and high‐energy hillslope processes that resulted in ubiquitous valley floor and piedmont aggradation, whereas the latter led to the dismantling of local base levels, transforming depositional units into new denudational landforms subject to the current climate dynamics. © 2020 John Wiley & Sons, Ltd. Quaternary sediments in the study area: CM01 and CM02 debris flows in the west of the area; CM03 massive fine‐grained colluvial units separated by gravelly layer; CM04 alluvial paleo‐plain located on the top of the hillslope and disconnected from the current drainage base level; CM05 paleo‐channel on top of hillslope close to a shear‐zone outcropping area; CM06 colluvial deposits to east of the study area on its highest elevations; CM07 and