The Experts below are selected from a list of 294 Experts worldwide ranked by ideXlab platform
Irina Artemieva - One of the best experts on this subject based on the ideXlab platform.
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The Tibet Lithosphere is not all hot
2020Co-Authors: Bing Xia, Irina Artemieva, Hans ThyboAbstract:<p>We calculated the thermal Lithosphere structure of Tibet and adjacent regions based on the new thermal isostasy method. Moho depth is constrained by the published receiver function results. The calculated surface heat flow in the surrounded Tarim, North China, and Yangtze cratons have a good match with the real measurements of surface heat flow. We recognize the northern Tibet anomaly where has a relatively thin Lithosphere with a thermal thickness of <80 km and surface heat flow of >80 - 100 mW/m 2 may cause by the removal of lithospheric mantle and upwelling of asthenosphere. In Lhasa Block, the cold and thick Lithosphere (>200 km) with a surface heat flow of 40 - 50 mW/m 2. In the east Tibet, the heterogeneous thermal Lithosphere does not follow the widely spread large scale strike-slip faults and suggested that the faults do not cut down to the Lithosphere. The surrounding cratons have different thermal Lithosphere features. The Tarim and Yangtze cratons show typical cold and thick Lithosphere with a Lithosphere of >200km and surface heat flow of <50 mW/m2. The western North China Craton has an intermated Lithosphere with a thickness of 120-200km and surface heat flow of 45-60 mW/m2. Our result suggested that high and flat Tibet has different isostatic compensation in different blocks. The heterogeneous Lithosphere thermal structure of the Tibet suggested that the uplife force drive are difference in Tibet.</p><div> <div>&#160;</div> </div>
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The Lithosphere: An Interdisciplinary Approach
2011Co-Authors: Irina ArtemievaAbstract:Foreword Preface 1. What is the Lithosphere? 2. Age of the Lithosphere 3. Seismic structure of the Lithosphere 4. Thermal regime of the Lithosphere from heat flow data 5. Thermal state of the Lithosphere from non-thermal data 6. CBL and lithospheric density from petrologic and geophysical data 7. Electrical structure of the Lithosphere 8. Flexure and rheology 9. Evolution of the Lithosphere 10. Summary of lithospheric properties References Index.
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thermal thickness and evolution of precambrian Lithosphere a global study
Journal of Geophysical Research, 2001Co-Authors: Irina Artemieva, Walter D MooneyAbstract:The thermal thickness of Precambrian Lithosphere is modeled and compared with estimates from seismic tomography and xenolith data. We use the steady state thermal conductivity equation with the same geothermal constraints for all of the Precambrian cratons (except Antarctica) to calculate the temperature distribution in the stable continental Lithosphere. The modeling is based on the global compilation of heat flow data by Pollack et al. [1993] and more recent data. The depth distribution of heat-producing elements is estimated using regional models for ∼300 blocks with sizes varying from 1°×1° to about 5°×5° in latitude and longitude and is constrained by laboratory, seismic and petrologic data and, where applicable, empirical heat flow/heat production relationships. Maps of the lateral temperature distribution at depths 50, 100, and 150 km are presented for all continents except Antarctica. The thermal thickness of the Lithosphere is calculated assuming a conductive layer overlying the mantle with an adiabat of 1300°C. The Archean and early Proterozoic Lithosphere is found to have two typical thicknesses, 200–220 km and 300–350 km. In general, thin (∼220 km) roots are found for Archean and early Proterozoic cratons in the Southern Hemisphere (South Africa, Western Australia, South America, and India) and thicker (>300 km) roots are found in the Northern Hemisphere (Baltic Shield, Siberian Platform, West Africa, and possibly the Canadian Shield). We find that the thickness of continental Lithosphere generally decreases with age from >200 km beneath Archean cratons to intermediate values of 200±50 km in early Proterozoic Lithosphere, to about 140±50 km in middle and late Proterozoic cratons. Using known crustal thickness, our calculated geotherms, and assuming that isostatic balance is achieved at the base of the Lithosphere, we find that Archean and early Proterozoic mantle Lithosphere is 1.5% less dense (chemically depleted) than the underlying asthenosphere, while middle and late Proterozoic subcrustal Lithosphere should be depleted by ∼0.6–0.7%. Our results suggest three contrasting stages of Lithosphere formation at the following ages: >2.5 Ga, 2.5–1.8 Ga, and <1.8 Ga. Ages of komatiites, greenstone belts, and giant dike swarms broadly define similar stages and apparently reflect secular changes in mantle temperature and, possibly, convection patterns.
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Lithosphere: What is the Lithosphere?
Lithosphere, 1Co-Authors: Irina ArtemievaAbstract:“Unfortunately, the term Lithosphere has recently been applied to many other concepts. The term is now in use with widely different meanings and implications.” D. L. Anderson (1995) “How wonderful that we have met with a paradox. Now we have some hope of making progress.” Niels Bohr The Lithosphere forms the outer (typically, 50–300 km thick) rigid shell of the Earth. It includes the crust and, in general, some non-convecting part of the upper mantle called the lithospheric mantle (Fig. 1.1). Oceanic Lithosphere is recycled into the mantle on a 200 Ma scale, whereas the study of the continental Lithosphere is of particular importance since it offers the only possibility of unraveling the tectonic and geologic history of the Earth over the past c . 4 Ga. Knowledge of the structure, composition, and secular evolution of the Lithosphere is crucial for the understanding of the geological evolution of the Earth since its accretion, including understanding the processes behind the formation of the early Lithosphere, the processes behind plate tectonics, and Lithosphere–mantle interaction. Many of these processes are closely linked to processes in the deep Earth and its secular cooling. Human society is strongly dependent on knowledge of the geodynamic processes in the Lithosphere which manifest themselves as variations in topography and bathymetry, deposition of minerals many of which occur only in specific lithospheric settings, and high-impact geologic hazards. Understanding processes in the deep Earth is impossible without knowledge of Lithosphere structure.
Claude Jaupart - One of the best experts on this subject based on the ideXlab platform.
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Secular cooling and thermal structure of continental Lithosphere
Earth and Planetary Science Letters, 2007Co-Authors: Chloe Michaut, Claude JaupartAbstract:Abstract Temperatures in thick continental Lithosphere do not adjust rapidly to secular changes of mantle temperature and in-situ radioactive decay. In the past, enhanced heat production may have led to geotherms that turn over above the base of the Lithosphere, such that the lower Lithosphere was hotter than, and was losing heat to, the underlying convecting mantle. Lithosphere with a turning geotherm would be unstable, undergoing delamination due to convective shear stresses imparted by the underlying mantle and in-situ partial melting if the lithospheric mantle contains small amounts of water and carbon. Both processes act to stabilize continental roots through reductions of lithospheric thickness and in-situ heat production, and hence may be responsible for the present-day characteristics of those roots that have survived until today. According to these arguments, a stable thermal structure requires that the average heat production rate in the lithospheric mantle does not exceed a critical value which depends on Lithosphere thickness. The threshold value of heat production is 0.025 μW m − 3 in Lithosphere that is thicker than 300 km. Cratonic roots that grow by underplating of oceanic Lithosphere in a subduction environment undergo an initial heating phase which may lead to partial melting and to the formation of near-solidus mantle melts without any external heating event involved.
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Secular cooling and thermal structure of continental Lithosphere
Earth and Planetary Science Letters, 2007Co-Authors: Chloe Michaut, Claude JaupartAbstract:International audienceTemperatures in thick continental Lithosphere do not adjust rapidly to secular changes of mantle temperature and in-situ radioactive decay. In the past, enhanced heat production may have led to geotherms that turn over above the base of the Lithosphere, such that the lower Lithosphere was hotter than, and was losing heat to, the underlying convecting mantle. Lithosphere with a turning geotherm would be unstable, undergoing delamination due to convective shear stresses imparted by the underlying mantle and in-situ partial melting if the lithospheric mantle contains small amounts of water and carbon. Both processes act to stabilize continental roots through reductions of lithospheric thickness and in-situ heat production, and hence may be responsible for the present-day characteristics of those roots that have survived until today. According to these arguments, a stable thermal structure requires that the average heat production rate in the lithospheric mantle does not exceed a critical value which depends on Lithosphere thickness. The threshold value of heat production is 0.025 μW m− 3 in Lithosphere that is thicker than 300 km. Cratonic roots that grow by underplating of oceanic Lithosphere in a subduction environment undergo an initial heating phase which may lead to partial melting and to the formation of near-solidus mantle melts without any external heating event involved
Chloe Michaut - One of the best experts on this subject based on the ideXlab platform.
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Secular cooling and thermal structure of continental Lithosphere
Earth and Planetary Science Letters, 2007Co-Authors: Chloe Michaut, Claude JaupartAbstract:Abstract Temperatures in thick continental Lithosphere do not adjust rapidly to secular changes of mantle temperature and in-situ radioactive decay. In the past, enhanced heat production may have led to geotherms that turn over above the base of the Lithosphere, such that the lower Lithosphere was hotter than, and was losing heat to, the underlying convecting mantle. Lithosphere with a turning geotherm would be unstable, undergoing delamination due to convective shear stresses imparted by the underlying mantle and in-situ partial melting if the lithospheric mantle contains small amounts of water and carbon. Both processes act to stabilize continental roots through reductions of lithospheric thickness and in-situ heat production, and hence may be responsible for the present-day characteristics of those roots that have survived until today. According to these arguments, a stable thermal structure requires that the average heat production rate in the lithospheric mantle does not exceed a critical value which depends on Lithosphere thickness. The threshold value of heat production is 0.025 μW m − 3 in Lithosphere that is thicker than 300 km. Cratonic roots that grow by underplating of oceanic Lithosphere in a subduction environment undergo an initial heating phase which may lead to partial melting and to the formation of near-solidus mantle melts without any external heating event involved.
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Secular cooling and thermal structure of continental Lithosphere
Earth and Planetary Science Letters, 2007Co-Authors: Chloe Michaut, Claude JaupartAbstract:International audienceTemperatures in thick continental Lithosphere do not adjust rapidly to secular changes of mantle temperature and in-situ radioactive decay. In the past, enhanced heat production may have led to geotherms that turn over above the base of the Lithosphere, such that the lower Lithosphere was hotter than, and was losing heat to, the underlying convecting mantle. Lithosphere with a turning geotherm would be unstable, undergoing delamination due to convective shear stresses imparted by the underlying mantle and in-situ partial melting if the lithospheric mantle contains small amounts of water and carbon. Both processes act to stabilize continental roots through reductions of lithospheric thickness and in-situ heat production, and hence may be responsible for the present-day characteristics of those roots that have survived until today. According to these arguments, a stable thermal structure requires that the average heat production rate in the lithospheric mantle does not exceed a critical value which depends on Lithosphere thickness. The threshold value of heat production is 0.025 μW m− 3 in Lithosphere that is thicker than 300 km. Cratonic roots that grow by underplating of oceanic Lithosphere in a subduction environment undergo an initial heating phase which may lead to partial melting and to the formation of near-solidus mantle melts without any external heating event involved
Luce Fleitout - One of the best experts on this subject based on the ideXlab platform.
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Numerical simulations of the cooling of an oceanic Lithosphere above a convective mantle
Physics of the Earth and Planetary Interiors, 2001Co-Authors: Caroline Dumoulin, Mariepierre Doin, Luce FleitoutAbstract:Numerical simulations of two-dimensional Rayleigh-Bénard convection are designed to study lithospheric cooling above a convective mantle. A strongly temperature-and pressure-dependent viscosity fluid is heated from below or from within. An imposed velocity at the surface of the box mimicks the plate motion between the ridge on one side and the subduction zone on the other side. As the Lithosphere cools, its upper part remains rigid and therefore conductive, while its bottom part is convectively unstable. Dripping instabilities are not observed close to the ridge. Nevertheless, the material flows along the slope defined by the lower part of the Lithosphere and feeds the first descending drip. Afterwards, cold downgoing instabilities develop continuously and randomly at the base of the Lithosphere and are replaced by hot material from the convecting core of the box. The Lithosphere continues to thicken even after the onset of the first instability. Surface heat flow, subsidence and lithospheric temperature structure obtained by the convective simulations are compared to the predictions of three conductive models: the Plate, Chablis, and modified Chablis models. These models differ by their applied bottom boundary condition which represents the Lithosphere/asthenosphere convective coupling, i.e. by the presence or absence of instabilities developing at the base of the Lithosphere. The conductive model which best explains the lithospheric cooling obtained by convective simulations is the modified Chablis model. In this model, a variable heat flow (depending upon the viscosity at the base of the Lithosphere) is applied along an isotherm located in the lower unstable part of the Lithosphere.
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mantle convection and stability of depleted and undepleted continental Lithosphere
Journal of Geophysical Research, 1997Co-Authors: Mariepierre Doin, Luce Fleitout, Ulrich R ChristensenAbstract:We address the question of how convective processes control the thicknesses of oceanic and continental Lithospheres. The numerical convection model involves a Newtonian rheology which depends on temperature and pressure. A repeated plate tectonic cycle is modeled by imposing a time-dependent surface velocity. One part of the surface, representing a continent, never subducts. The asymptotic equilibrium thickness of the Lithosphere varies with the viscosity at the base of the Lithosphere, but is not directly sensitive to the pressure dependence of the viscosity law and to the plate velocity. For small activation volumes, and average upper mantle viscosities deduced from postglacial rebound, the equilibrium plate thickness is more than 400 km (regimes 1 and 2). The equilibrium thickness of the oceanic Lithosphere (around 100 km) implies that the viscosity in the asthenosphere is less than 7×1018 Pa s. Only models with strongly pressure-dependent viscosity laws (activation volumes greater than 9×10−6 m3/mol) are able to reconcile this value with the average upper mantle viscosity (5×1020 Pa s). For these models, there are two lithospheric thicknesses such that the heat supplied by convection at the base of the Lithosphere equals the surface conductive heat flow (regime 3). They could be that of an aged oceanic Lithosphere and that of a shield lithospheric root. They indeed appear as points of prefered thickness in our numerical models. However, convection triggered by the lateral density jumps at the boundaries between the root and the thinner Lithosphere slowly destabilizes the thick Lithosphere. A plausible degree of chemical buoyancy in a depleted lithospheric root does not prevent convective erosion. In our simulations, long-term stability of a cratonic lithospheric root is best achieved when its material is both buoyant and more viscous than the surrounding mantle. Extensive devolatilization of the refractory rocks forming the root is invoked to explain this viscosity increase.
Xinguo Wang - One of the best experts on this subject based on the ideXlab platform.
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joint modeling of Lithosphere and mantle dynamics sensitivity to viscosities within the Lithosphere asthenosphere transition zone and d layers
Physics of the Earth and Planetary Interiors, 2019Co-Authors: Xinguo Wang, William E Holt, A GhoshAbstract:Abstract Although mantle rheology is one of the most important properties of the Earth, how a radial mantle viscosity structure affects Lithosphere dynamics is still poorly known, particularly the role of the Lithosphere, asthenosphere, transition zone, and D" layer viscosities. Using constraints from the geoid, plate motions, and strain rates within plate boundary zones, we provide important new refinements to the radial viscosity profile within the key layers of the Lithosphere, asthenosphere, transition zone, and D" layer. We follow the approach of the joint modeling of Lithosphere and mantle dynamics (Ghosh and Holt, 2012; Ghosh et al., 2013b, 2019; Wang et al., 2015) to show how the viscosities within these key layers influence Lithosphere dynamics. We use the viscosity structure SH08 (Steinberger and Holme, 2008) as a starting model. The density variations within the mantle are derived from the tomography models which, based on prior modeling, had provided a best fit to the surface observables (Wang et al., 2015). Our results show that narrow viscosity ranges of moderately strong Lithosphere (2.6–5.6 × 1022 Pa-s) and moderately weak transition zone (5–9.3 × 1020 Pa-s), as well as slightly large ranges of moderately weak asthenosphere (5–34 × 1019 Pa-s) and D" layer (4.8–18 × 1020 Pa-s), are necessary to match all the surface observables. We also find that a very strong Lithosphere (>8.6 × 1022 Pa-s) along with a weak asthenosphere (
