Water Tracing Experiments in Low-pH Quartzite Karst Water, Chapada Diamantina, Northeastern Brazil

Auler, Augusto S.; Meus, Philippe; Pessoa, Paulo Fernando Pereira

doi:10.1007/978-3-030-14015-1_21

Cited by 2 publications

(2 citation statements)

References 17 publications

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“…The lowest pH values are found in the area with the highest moisture content, which might be enhanced by the water presence itself. Groundwater derived from the sandstone bedrock tends to have a more acidic pH (Auler et al, 2020;Mecchia et al, 2014;Sauro et al, 2019) and enhanced SiO 2 dissolution. The high moisture content in the bottom South corner of the sequence is likely the result of groundwater coming in through the sandstone bedrock.…”

Section: Site Taphonomymentioning

confidence: 99%

Making the Invisible Stratigraphy Visible: A Grid-Based, Multi-Proxy Geoarchaeological Study of Umhlatuzana Rockshelter, South Africa

et al. 2021

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Umhlatuzana rockshelter is an archaeological site with an occupational record covering the Middle Stone Age, Later Stone Age, and Iron Age. The presence of both Middle and Later Stone Age assemblages makes Umhlatuzana the ideal location for the study of the MSA–LSA transition (20–40 ka) in southern Africa. This transitional period is characterized by important modifications in stone tool technology, from prepared core technology to a toolkit based on microlith production. These changes are argued to have occurred in response to changes in climate and environment leading up to the Last Glacial Maximum. The deposits bearing the transitional assemblages at Umhlatuzana rockshelter appear homogeneous with no visible stratigraphic boundaries. This study integrates geoarchaeological techniques in order to explore fine-resolution geochemical differentiations of the sediments that are macroscopically invisible, and that will provide insight into (post-)depositional processes over time. Samples were systematically retrieved from the western profile of the site following a grid-based sampling strategy and analyzed for pH, elemental composition (XRF), and Magnetic Susceptibility. Additionally, the results were integrated with preliminary micromorphological observations. Our study reveals a steady, gradual change in the geochemistry of the deposits throughout the Pleistocene, related to a combination of environmental change and occupation intensity. We suggest that the part of the sequence reported to bear Middle to Later Stone Age transitional industries is characterized by wetter environmental conditions compared to the underlying deposits. Additionally, we support results from previous studies that excluded large scale post-depositional movement of the sedimentary sequence. Our study offers a successful multi-proxy approach to systematically sample and study archaeological deposits at the macro and micro scale, integrating a variety of geoarchaeological techniques. The approach provides insight into the depositional and post-depositional history of the site, and allows for questions of stratigraphic integrity, anthropogenic input, preservation, and environmental change to be addressed.

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Section: Site Taphonomymentioning

confidence: 99%

Making the Invisible Stratigraphy Visible: A Grid-Based, Multi-Proxy Geoarchaeological Study of Umhlatuzana Rockshelter, South Africa

et al. 2021

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“…They drew attention to the need to define the scales at which higher permeabilities may play a significant role for flow (at least 100 m). Auler et al (2020) studied fast flow routes in the quartzites of Chapada Diamantina (Bahia, Brazil). These routes are guided by bedding planes and large-scale fractures and, even during low stage conditions, could reach maximum velocities of 60 m/h.…”

Section: Introductionmentioning

confidence: 99%

Tracer tests to infer the drainage of the multiple porosity aquifer of Luxembourg Sandstone (Grand-Duchy of Luxembourg): implications for drinking water protection

Meus¹,

Willems

2021

Hydrogeol J

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The Luxembourg Sandstone is the main strategic aquifer of the Grand-Duchy of Luxembourg, providing one third of the total drinking water resource in the country. In the unconfined part, the aquifer discharges through more than 400 springs, which are used for supply. The long-lasting diffuse contamination by pesticides (more recently Metolachor ESA) has been previously simulated assuming the aquifer as an equivalent porous medium, and using environmental tracers and baseflow characteristics. A statistical analysis of the whole data set of artificial tracer tests made for this aquifer (112 injections involving 102 springs) emphasized the role of the main fissures (NE-SW) for preferential groundwater flow and the importance of including them in a conceptual model involving a multiple-porosity aquifer. The results show that these fissures are influencing the whole flow system. The average peak velocity is 16 m/h and the average first arrival (maximum) velocity is 52 m/h (32 m/h for injection-well to spring traces alone), with a recorded maximum velocity of 350 m/h. The threats of infiltrating streams within catchments have also been characterized, suggesting the usefulness of tracer tests for optimizing protective measures. The main benefit of the study is the improvement in the ability to delineate safeguard zones accurately, according to more representative velocities and the strong anisotropy.

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Water Tracing Experiments in Low-pH Quartzite Karst Water, Chapada Diamantina, Northeastern Brazil

Cited by 2 publications

References 17 publications

Making the Invisible Stratigraphy Visible: A Grid-Based, Multi-Proxy Geoarchaeological Study of Umhlatuzana Rockshelter, South Africa

Making the Invisible Stratigraphy Visible: A Grid-Based, Multi-Proxy Geoarchaeological Study of Umhlatuzana Rockshelter, South Africa

Tracer tests to infer the drainage of the multiple porosity aquifer of Luxembourg Sandstone (Grand-Duchy of Luxembourg): implications for drinking water protection

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