Lithosphere Mechanical Behavior Inferred From Tidal Gravity Anomalies: A Comparison of Africa and South America

Mantovani, Marta Sílvia Maria; Shukowsky, Wladimir; Freitas, S. de; Neves, Benjamim Bley de Brito

doi:10.1190/sbgf2007-469

Cited by 4 publications

(14 citation statements)

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“…Another is a recent study by Tassara et al [2007], who used wavelet Bouguer coherence to obtain spatial variations in T e . The results of these two studies, however, differ markedly: Mantovani et al [2005a] obtained large (T e > 70 km) estimates over the Andean domain comparable to those in cratonic South America. Tassara et al [2007], on the other hand, found T e in the Andes to be much lower than over the cratonic interior.…”

Section: Introductionmentioning

confidence: 81%

“…We focus on the results in the stable South American platform, first describing the tectonic domains of cratonic South America, the data sources and processing, and the methodology employed to estimate T e . We then compare our results to those of Tassara et al [2007] and Mantovani et al [2005a]. Subsequently, we examine the relationship of T e to terrane age and other proxies for lithospheric structure such as shear wave velocity and heat flow.…”

Section: Introductionmentioning

confidence: 94%

“…Most have focused on the Andean domain [Tassara, 2005;Stewart and Watts, 1997;Watts et al, 1995]. An exception are those of Mantovani et al [2005a], who estimate T e on the basis of an empirical correlation between tidal forcing and elastic thickness. Another is a recent study by Tassara et al [2007], who used wavelet Bouguer coherence to obtain spatial variations in T e .…”

Section: Introductionmentioning

confidence: 99%

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Effective elastic thickness of South America and its implications for intracontinental deformation

Pérez‐Gussinyé

Lowry

Watts

2007

Geochem Geophys Geosyst

111

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[1] The flexural rigidity or effective elastic thickness of the lithosphere, T e , primarily depends on its thermal gradient and composition. Consequently, maps of the lateral variability of T e in continents reflect their lithospheric structure. We present here a new T e map of South America generated using a compilation of satellite-derived (GRACE and CHAMP missions) and terrestrial gravity data (including EGM96 and SAGP), and a multitaper Bouguer coherence technique. Our T e maps correlate remarkably well with other proxies for lithospheric structure: areas with high T e have, in general, high lithospheric mantle shear wave velocity and low heat flow and vice versa. In this paper we focus on the T e of the stable platform. We find that old cratonic nuclei (mainly Archean and Early/Middle Proterozoic) have, in general, high T e (>70 km), while the younger Patagonian Phanerozoic terrane has much lower T e (20-30 km), suggesting that T e is related to terrane age as has already been noted in Europe. Within cratonic South America, T e variations are observed at regional scale: relatively lower T e occurs at sites that have been repeatedly reactivated throughout geological history as major sutures, rift zones, and sites of hot spot magmatism. Today, these low T e areas are surrounded by large cratonic nuclei. They concentrate most of the intracontinental seismicity and exhibit relatively high surface heat flow and low seismic velocity at 100 km depth. This implies that intracontinental deformation focuses within relatively thin, hot, and hence weak lithosphere, that cratonic interiors are strong enough to inhibit tectonism, and that the differences in lithospheric rigidity, structure, and composition between stable cratons and sites of intracontinental deformation are not transient, and may have been maintained, in some cases, for at least 500 m.y.

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Section: Introductionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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Effective elastic thickness of South America and its implications for intracontinental deformation

Pérez‐Gussinyé

Lowry

Watts

2007

Geochem Geophys Geosyst

111

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“…Pérez-Gussinyé et al (2007), baseando-se em valores na aplicação da técnica da coerência em dados topográficos e gravimétricos (anomalias Bouguer) derivados de modelos geopotenciais e obtidos em levantamentos tradicionais, obtiveram valores de T e para região superiores a 70 km. Já Mantovani et al (2005), por meio do estudo da componente M2 das marés de gravidade, determinaram valores entre 76 e 89 km para a espessura elástica efetiva deste segmento litosférico.…”

Section: Conclusõesunclassified

“…Os resultados aqui apresentados serão comparados com outros obtidos em estudos que visaram determinar valores de espessura elástica efetiva para o continente sul-americano, mas que utilizaram diferentes metodologias (Mantovani et al, 2005;Tassara et al, 2007;Pérez-Gussinyé et al, 2007).…”

Section: Introductionunclassified

Estimativa da espessura elástica efetiva da litosfera do sul do cráton são francisco usando dados da missão Grace

Oliveira¹,

Endo²,

Blitzkow³

2008

Rev. Bras. Geof.

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ABSTRACT. This paper presents the estimates of effective elastic thickness (T e) from free-air anomalies/geoid undulations and topography data in the southern São Francisco Craton, by using admittance function technique. The gravity field elements have been calculated from geopotential model GGM02C (GRACE mission).The observed admittance was computed by dividing the cross-spectra of the free-air anomalies/geoid undulations by the power of topography. Theoretical admittances were estimated based on two hypothesis of flexural compensation mechanism: surface topographic loads or loads beneath of lithosphere. The best fit was obtained by using the second hypothesis, were a negative density contrast (located at depth of 150 km) suggested 45 km for T e value. This low value of elastic thickness, combined with high heat flow and positive geoid undulations, can be explained by the presence of density perturbations in the mantle, which are associated with the chemical depletion and thermal anomalies, both are correlated with the complex geodynamic evolution of this important cratonic area in the South American plate.Keywords: gravity, geoid, effective elastic thickness, southern São Francisco Craton. RESUMO.Este trabalho apresenta os resultados de espessuras elásticas efetivas (T e) calculados com base em anomalias ar-livre/ondulações do geóide e topografia na região do Cráton São Francisco Meridional, por meio da técnica da função admitância. Os elementos do campo gravitacional foram obtidos utilizando-se o modelo geopotencial GGM02C (Missão GRACE ). A função admitância observada foi determinada pela divisão do espectro cruzado das anomalias ar-livre/ondulações do geóide e da topografia pelo espectro de potência da topografia. Numa etapa posterior foram construídas curvas de função admitância teóricas, supondo-se duas hipóteses de compensação isostática flexural: a topografia comoúnica carga atuante ou a ação de cargas na base da litosfera. Os melhores ajustes foram obtidos adotando-se a segunda suposição, a uma profundidade média de 150 km, com uma estimativa para T e de cerca de 45 km. A princípio, este valor baixo de espessura elástica, associado a um alto fluxo térmico e ondulações positivas do geóide, pode ser explicado pela presença de perturbações nas densidades mantélicas da região, originadas a partir de processos de empobrecimento químico e perturbações termais, ambos ocorrentes durante a complexa evolução geodinâmica desta importante região cratônica da placa Sul-Americana.Palavras-chave: gravimetria, geóide, espessura elástica efetiva, Cráton São

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International Polar Year 2007–2008

Carlson

2021

Encyclopedia of Solid Earth Geophysics

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Lithosphere Mechanical Behavior Inferred From Tidal Gravity Anomalies: A Comparison of Africa and South America

Cited by 4 publications

References 3 publications

Effective elastic thickness of South America and its implications for intracontinental deformation

Effective elastic thickness of South America and its implications for intracontinental deformation

Estimativa da espessura elástica efetiva da litosfera do sul do cráton são francisco usando dados da missão Grace

International Polar Year 2007–2008

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