Reduction of topography effect in inductive electromagnetic profiles: application on coastal sambaqui (shell mound) archaeological site in Santa Catarina state, Brazil

Santos, Vinicius Rocha; Porsani, Jorge Luís; Mendonça, Carlos Alberto; Rodrigues, Selma Isabel; DeBlasis, Paulo

doi:10.1016/j.jas.2009.05.014

Cited by 24 publications

(16 citation statements)

References 25 publications

(16 reference statements)

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“…Corrections are necessary in order to improve contrast between physical properties of background and subsurface targets. A good discussion about topographic drift correction can be found in Santos et al (2009). On the other hand, Sudduth et al (2001) showed that there is an increase in values of apparent ground conductivity with decreasing temperature, and vice versa.…”

Section: Acquisition and Data Treatmentmentioning

confidence: 99%

Comparing performance of instrumental drift correction by linear and quadratic adjusting in inductive electromagnetic data

Santos

Porsani

2011

Journal of Applied Geophysics

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Electromagnetic induction (EMI) method results are shown for vertical magnetic dipole (VMD) configuration by using the EM38 equipment. Performance in the location of metallic pipes and electrical cables is compared as a function of instrumental drift correction by linear and quadratic adjusting under controlled conditions. Metallic pipes and electrical cables are buried at the IAG/USP shallow geophysical test site in São Paulo City, Brazil. Results show that apparent electrical conductivity and magnetic susceptibility data were affected by ambient temperature variation. In order to obtain better contrast between background and metallic targets it was necessary to correct the drift. This correction was accomplished by using linear and quadratic relation between conductivity/susceptibility and temperature intending comparative studies. The correction of temperature drift by using a quadratic relation was effective, showing that all metallic targets were located as well deeper targets were also improved.

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Section: Acquisition and Data Treatmentmentioning

confidence: 99%

Comparing performance of instrumental drift correction by linear and quadratic adjusting in inductive electromagnetic data

Santos

Porsani

2011

Journal of Applied Geophysics

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“…Technological advances in the last decades have generated significant increase of geophysical investigations applied to archaeological studies as can be observed in the literature (Chamberlain et al, 2000;Weinstein-Evron et al, 2003;Persson and Olofsson, 2004;Barton and Fenwick, 2005;Sauck et al, 2006;Santos et al, 2009;Rodrigues et al, 2009). According to Reynolds (1997) and Conyers (2004), among others, the use of non-invasive geophysical methods has been contributing effectively with nondestructive actions, orienting archaeological excavations, and optimizing time and costs related with archaeological surveys and excavations.…”

Section: Introductionmentioning

confidence: 99%

“…Despite this scenario, recent research projects have been incorporating geophysical methods in order to characterize archaeological sites, to identify areas with great archaeological potential, and guide archaeological excavations (Roosevelt, 1991;Cezar et al, 2001;Schimmel et al, 2002;Bevan and Roosevelt, 2003;Fen, 2006;Santos et al, 2009;Rodrigues et al, 2009). Roosevelt (1991) applied GPR, electric and magnetic methods aiming at mapping archaeological sites associated with ceramic occupations in Marajó Island, in the mouth of the Amazon River, Pará state, Brazil.…”

Section: Introductionmentioning

confidence: 99%

“…Details about its construction and some GPR results can be found in Porsani et al (2006), Rodrigues and Porsani (2006), Porsani and Sauck (2007). Santos et al (2009) used electrical conductivity profiles obtained with inductive electromagnetic method in a coastal shell mound, located in Santa Catarina state, southern Brazil, aiming the identification of geophysical anomalies with potential interest for excavation. The authors observed a linear dependence between conductivity values and topographical variation, which is rather conditioned by the presence of a variable water table depth or a conductive sediment layer.…”

Section: Introductionmentioning

confidence: 99%

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GPR survey at Lapa do Santo archaeological site, Lagoa Santa karstic region, Minas Gerais state, Brazil

Porsani

Jangelme²,

Kipnis

2010

Journal of Archaeological Science

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“…The application of geophysical techniques to shell mounds only began in the last decade, and such approaches focused initially on the ability of instruments (especially GPR) to map the spatial layout or extent of shell midden features, or the depth of the shell deposits Santos et al 2009;Thompson et al 2004). To date, there are very few studies documented on the magnetic susceptibility of shell mound deposits (see Connah et al 1976) and a reason for this may be due to their complex stratigraphy (Stein et al 2003).…”

Section: Methodsmentioning

confidence: 99%

Understanding Australia’s cultural history through archaeological geophysics

Lowe¹

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The aim of this thesis is to develop and apply geophysical methods for Australian archaeology. The methods focus on magnetic susceptibility and ground-penetrating radar (GPR). The techniques are contextualised through application to the following four key archaeological questions: 1) Can magnetic susceptibility assist in resolving questions surrounding the potential downward movement of stone artefacts in rockshelter deposits? 2) Is human occupation persistent through the changing climatic regime associated with the last glacial maximum (LGM) at a Pleistocene-aged rockshelter in interior Australia? 3) How might we identify burials in a geologically complex rockshelter deposit? 4) How might magnetic susceptibility contribute to knowledge about the formation of 'archaeologically instantaneous' shell matrix sites?In exploring these questions, research was conducted at two rockshelters in northern Australia and on three shell mounds in the Gulf of Carpentaria, Australia. Magnetic susceptibility studies were undertaken at Gledswood Shelter 1 (GS1), a rockshelter occupied at ca 38,000 BP, to understand its history and formation processes. An experimental burning program using off-site samples was conducted to confirm that magnetically enhanced sediments in the cultural deposits were the direct result of anthropogenic burning rather than natural fires, pedogenesis or weathering. This change coincides with the level at which stone artefacts appear in the sedimentary sequence, indicating that they are in situ and have not moved down from higher layers above. Demonstrating that an increase in magnetic susceptibility is associated with human occupation is a crucial development in Australian archaeology. This will provide an opportunity to link sediments and artefacts-and this is critical to comprehending the timing of initial occupation of the continent.Magnetic susceptibility data combined with micromorphology and geoarchaeological data also revealed that occupation was continuous through the LGM at GS1, without any abandonment of the site. GS1 is situated in a region that has been characterised as a potential corridor for early colonists moving into the arid interior. The appearance of stone artefacts in the deposits corresponding with an increase in magnetic susceptibility as well as clay and charcoal coatings on quartz grains in the Pleistocene units in thin section, indicate that the site was occupied through this period, thereby implying that water was at least locally available.Despite the absence of any obvious permanent water sources, water availability at the site is ii reliant on summer rainfall. This suggests that the monsoons driven by the Coral Sea off the northeast Australian coastline may have been active during this time. This has important implications for understanding climatic conditions during that period, and allows one to infer that water must have been available regionally for people to have maintained their use of the site.GPR carried out in advance of archaeological excavations at Madjedbe...

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Reduction of topography effect in inductive electromagnetic profiles: application on coastal sambaqui (shell mound) archaeological site in Santa Catarina state, Brazil

Cited by 24 publications

References 25 publications

Comparing performance of instrumental drift correction by linear and quadratic adjusting in inductive electromagnetic data

Comparing performance of instrumental drift correction by linear and quadratic adjusting in inductive electromagnetic data

GPR survey at Lapa do Santo archaeological site, Lagoa Santa karstic region, Minas Gerais state, Brazil

Understanding Australia’s cultural history through archaeological geophysics

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