High‐velocity lid of East Antarctica: Evidence of a depleted continental lithosphere

Kuge, K.; Fukao, Yoshio

doi:10.1029/2004jb003382

Cited by 13 publications

(9 citation statements)

References 45 publications

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“…The density best represents the middle point of each layer. The bottom of the model should be below the deepest lithospheric keels (<240 km, e.g., Kuge & Fukao, ), which are the main target of the present study. The uppermost layer with the central depth of 15 km is included to account for two possible uncertainties: (1) the crustal density and (2) the Moho depth in WANT and offshore, where it is relatively shallow.…”

Section: Methodsmentioning

confidence: 99%

“…Even less is known about the compositional variations in the Antarctic upper mantle. Kuge and Fukao () examined S and P velocity variations using broadband seismograms recorded at several stations within EANT and explained these with the presence of depleted continental lithosphere meaning high concentrations of olivine and a high magnesium number (Mg # = 100 Mg/(Mg + Fe)). On small scales, composition analysis has been conducted using xenolith data from rock exposure and glacier outlets (e.g., Goodge, ; Jacobs et al, ; Owada et al, ).…”

Section: Introductionmentioning

confidence: 99%

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3‐D Density, Thermal, and Compositional Model of the Antarctic Lithosphere and Implications for Its Evolution

Haeger

Kaban

Tesauro

et al. 2019

Geochem Geophys Geosyst

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We create a 3-D density, temperature, and composition model of the Antarctic lithosphere using an integrative approach combining gravity, topography, and tomography data with mineral physics constraints and seismic data on crustal structures. The latter is used to create a new Moho and crustal density model. Temperature and thermal density variations are estimated based on S wave velocities from two independent tomography models (SL2013sv and AN1-S). Results of the Antarctic continent show the well-known distinction between East and West Antarctica in temperature and density to a depth of about 200 km. Incorporating compositional variations in the temperature calculations increases temperatures in depleted regions by up to 150°C, giving improved insights into thermal structures. The thickness of the lithospheric root also varies strongly between these regions, with values below 100 km in the west and above 200 km in the east. Regions with negative compositional density variations (<−0.040 g/cm 3 at 100 km), high depletion (Mg # > 91.5), and low temperatures (<800°C; central Dronning Maud Land, along the east flank of the Transantarctic Mountains) are interpreted as Precambrian cratonic fragments. Nearly undepleted lithosphere is found in the Lambert Graben and the Aurora Subglacial Basin and is attributed to Mesozoic rifting activity that has caused lithospheric rejuvenation.Plain Language Summary Antarctica remains one of the least studied areas on Earth, because large ice masses and climate conditions strongly hinder measurements. It plays an important role in global phenomena such as sea level change. In order to understand and predict these processes, we need knowledge about the heat coming from the Earth's interior. It has been recently recognized that the thermal state of the lithosphere, the rigid outer shell of the Earth, plays an important role in controlling dynamics of the ice shield and, thus, global sea level changes. Therefore, we create a model of the lithosphere describing the variation in temperature, density, and composition. Before, such models were created by using some single data set (usually seismic tomography). We employ a new integrative approach, combining several data sets to create a comprehensive 3-D model of the Antarctic lithosphere. Combination of various data sets gives more robust models than when using a single approach. Our results of the Antarctic continent show strong differences between East and West Antarctica in temperature and density to a depth of about 200 km. Regions with negative compositional density variations and low temperatures are identified within East Antarctica and are interpreted as being substantially older than the surrounding continent.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

3‐D Density, Thermal, and Compositional Model of the Antarctic Lithosphere and Implications for Its Evolution

Haeger

Kaban

Tesauro

et al. 2019

Geochem Geophys Geosyst

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“…(2) Antarctica is another example of a huge continental region with almost no borehole heat flow measurements (Engelhardt, 2004) and very limited geophysical data on its lithospheric structure. Recently, several attempts have been done to estimate the thermal regime of the continent using seismic tomography (Shapiro and Ritzwoller, 2004a,b;Kuge and Fukao, 2005) and satellite magnetic data (Maule et al, 2005). The TC1 model, based on the sparse available age data for Antarctica and the statistical relationship (Eq.…”

Section: The Tc1 Model: Some Examplesmentioning

confidence: 99%

Global 1°×1° thermal model TC1 for the continental lithosphere: Implications for lithosphere secular evolution

2006

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This paper reports a new 1°× 1°global thermal model for the continental lithosphere (TC1). Geotherms for continental terranes of different ages (N 3.6 Ga to present) constrained by reliable data on borehole heat flow measurements (Artemieva, I.M., Mooney, W.D. 2001. Thermal structure and evolution of Precambrian lithosphere: a global study. J. Geophys. Res 106, 16387-16414.), are statistically analyzed as a function of age and are used to estimate lithospheric temperatures in continental regions with no or lowquality heat flow data (ca. 60% of the continents). These data are supplemented by cratonic geotherms based on electromagnetic and xenolith data; the latter indicate the existence of Archean cratons with two characteristic thicknesses, ca. 200 and N 250 km. A map of tectono-thermal ages of lithospheric terranes complied for the continents on a 1°× 1°grid and combined with the statistical age relationship of continental geotherms (z = 0.04 ⁎ t + 93.6, where z is lithospheric thermal thickness in km and t is age in Ma) formed the basis for a new global thermal model of the continental lithosphere (TC1). The TC1 model is presented by a set of maps, which show significant thermal heterogeneity within continental upper mantle, with the strongest lateral temperature variations (as large as 800°C) in the shallow mantle. A map of the depth to a 550°C isotherm (Curie isotherm for magnetite) in continental upper mantle is presented as a proxy to the thickness of the magnetic crust; the same map provides a rough estimate of elastic thickness of old (N 200 Ma) continental lithosphere, in which flexural rigidity is dominated by olivine rheology of the mantle. Statistical analysis of continental geotherms reveals that thick (N 250 km) lithosphere is restricted solely to young Archean terranes (3.0-2.6 Ga), while in old Archean cratons (3.6-3.0 Ga) lithospheric roots do not extend deeper than 200-220 km. It is proposed that the former were formed by tectonic stacking and underplating during paleocollision of continental nuclei; it is likely that such exceptionally thick lithospheric roots have a limited lateral extent and are restricted to paleoterrane boundaries. This conclusion is supported by an analysis of the growth rate of the lithosphere since the Archean, which does not reveal a peak in lithospheric volume at 2.7-2.6 Ga as expected from growth curves for juvenile crust. A pronounced peak in the rate of lithospheric growth (10-18 km 3 /year) at 2.1-1.7 Ga (as compared to 5-8 km 3 /year in the Archean) well correlates with a peak in the growth of juvenile crust and with a consequent global extraction of massif-type anorthosites. It is proposed that large-scale variations in lithospheric thickness at cratonic margins and at paleoterrane boundaries controlled anorogenic magmatism. In particular, mid-Proterozoic anorogenic magmatism at the cratonic margins was caused by edge-driven convection triggered by a fast growth of the lithospheric mantle at 2.1-1.7 Ga. Belts of anorogenic magmatism within cratonic interiors can ...

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“…The average thickness of the continental crust of East Antarctica was 10-20 km larger than that of West Antarctica; the corresponding lithosphere of East Antarctica posed high-velocity layers down to a depth of 150 km. Moreover, an investigation by body wave propagation within the upper mantle of East Antarctica revealed the presence of a strikingly low-velocity anomaly in the 200-km depths underneath the lithosphere [9]. In order to explain the velocity models derived from both the observed and theoretical waveforms, the presence of the unique chemical composition and thermal gradient for the "depleted mantle" was required, which characterizes the Archean age in the Earth's history.…”

Section: Antarctic Regionmentioning

confidence: 99%

Seismological Studies on the Deep Interiors of the Earth Viewed from the Polar Region

Kanao¹

2018

Polar Seismology - Advances and Impact

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Seismological studies on the deep interiors of the Earth (depth range from the mantle to the inner core) viewed from the polar region have an advantage to promote global geosciences, such as for revealing the heterogeneous structural variations along the latitude from the poles to the equators. In this chapter, major seismological investigations, which had been held during the IPY, particularly newly identified founding of deep interiors of the Earth, will be introduced.

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High‐velocity lid of East Antarctica: Evidence of a depleted continental lithosphere

Cited by 13 publications

References 45 publications

3‐D Density, Thermal, and Compositional Model of the Antarctic Lithosphere and Implications for Its Evolution

3‐D Density, Thermal, and Compositional Model of the Antarctic Lithosphere and Implications for Its Evolution

Global 1°×1° thermal model TC1 for the continental lithosphere: Implications for lithosphere secular evolution

Seismological Studies on the Deep Interiors of the Earth Viewed from the Polar Region

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