Quartz OSL sensitivity from dating data for provenance analysis of pleistocene and holocene fluvial sediments from lowland Amazonia

Author(s)

Souza, Priscila E. ; Pupim, Fabiano N. ; Mazoca, Carlos E. M. ; del Rio, Ian ; Mineli, Thays D. ; Rodrigues, Fernanda C. G. ; Porat, Naomi ; Hartmann, Gelvam A. ; Sawakuchi, Andre O.

• Document type: Journal article
• Source: QUATERNARY GEOCHRONOLOGY; v. 74, p. 10-pg., 2023-01-29.

Abstract

The properties of the quartz luminescence signal have been shown to be a useful tool for sediment provenance analysis. These provenance studies are based on the sensitivity of the fast optically stimulated luminescence (OSL) component, which is also used for sediment dating. Besides the widespread occurrence of quartz in terrigenous sediments, OSL sensitivity can be acquired using relatively fast and low-cost measurements compared to sediment provenance analysis methods based on accessory minerals or isotopes. Additionally, laboratories worldwide already have an extensive database of recorded quartz OSL signals primarily measured for dating studies, and these data could potentially be repurposed for provenance analysis of Quaternary sedi-mentary systems through OSL sensitivity calculation. Here, we investigate the use of OSL quartz signals measured in sediment dating surveys for OSL sensitivity calculation and evaluation of changes in sediment sources. The OSL sensitivity was calculated and expressed as %BOSLF, which corresponds to the percentage of the fast OSL component signal (blue stimulation) to the total OSL curve; such approach is advantageous as it does not require any normalisation of the measured signal intensity to dose or aliquot size (weight). Three sets of samples from Amazonian fluvial sediments are investigated: two sets of Holocene floodplain sediments representing different sediment sources to the Amazonian fluvial system, i.e. the Amazon craton and the Andes Mountain belt, and a set of samples from the Ic ' a Formation, a paleo-fluvial system active during the Pleistocene whose provenance is not fully known. Results show that the quartz OSL signal derived from the first test doses (Tn) applied in dating protocols had the best performance for %BOSLF calculation when compared to results from a measurement protocol designed specifically for sediment provenance analysis. There is significant correlation (R2 = 88) be-tween sensitivities derived from Tn and a specific OSL provenance analysis protocol. The proposed approach indicates to be appropriate for sediment provenance analysis since it is able to discriminate signal differences among samples from known sources: Brazilian cratonic quartz yield high sensitivity values (mean %BOSLF >70), in contrast to the relatively lower values from Andean quartz (mean %BOSLF <50). In general, quartz OSL sensitivities from the Ic ' a Formation samples fall into the same range of modern sediments transported by the Ica ' and Japur ' a rivers draining the Andean Eastern Cordillera of Colombia and Ecuador. We also observe a decrease in quartz OSL sensitivity during the Holocene, notably after 4 ka, with younger deposits showing lower sensi-tivity. Sediment provenance variations are discussed in terms of watershed rearrangement and/or precipitation -driven changes during the Late Pleistocene and Holocene across Amazonia. (AU)

• FAPESP's process: 20/11047-1 - Characterizing the establishment of the watershed divide between the Orinoco and Amazonas river basins and its influence on paleoenvironments and biotic diversification
• Grantee: Fabiano do Nascimento Pupim
• Support Opportunities: Regular Research Grants
• FAPESP's process: 18/12472-8 - Origin and chronology of sandy substrates in Amazonia: implications for quaternary evolution of open vegetation ecosystems
• Grantee: Fernanda Costa Gonçalves Rodrigues
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 19/20588-9 - Understanding the climate-tectonic interaction in Western Amazonia (Acre Basin) during the Quaternary using luminescence techniques
• Grantee: Ian Aitor Del Rio Garcia
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 21/14022-2 - Reorganization of the Western Amazon drainage system during the Neogene and Quaternary based on the provenance of sediments solved by luminescence techniques
• Grantee: Priscila Emerich Souza
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 18/23899-2 - Trans-Amazon Drilling Project: origin and evolution of the forests, climate, and hydrology of the South American tropics
• Grantee: André Oliveira Sawakuchi
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants