Heat flow and heat generation in the Archaean Dharwar cratons and implications for the Southern Indian Shield geotherm and lithospheric thickness

Gupta, Mohan L.; Sundar, A.; Sharma, Somya

doi:10.1016/0040-1951(91)90275-w

Cited by 106 publications

(43 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Temperature-depth calculations depend heavily on the heat production value assigned to the upper crust. Thus, for WDC and EDC, we use the detailed compilation of Gupta et al (1991) for the Dharwar craton. In case of EDC, we have not considered anomalous heat generation value of Hyderabad granitic terrain and for WDC, we restrict only to the values belonging to the Chitradurga supracrustal belt and its surrounding areas.…”

Section: Heat Flow Distribution Temperature Regime and Geoelectric Smentioning

confidence: 99%

“…Our recent detailed study (Pandey et al, 2002) suggests that highly radioactive granitic layer at Hyderabad does not extend beyond a kilometer or so at depth. For SGT, heat generation Gupta and Rao (1970), Gupta et al (1987Gupta et al ( , 1991, Roy and Rao (2000) and Rao et al (1976Rao et al ( , 2001. NSGT and SSGT denote Northern and Southern block of SGT.…”

Section: Heat Flow Distribution Temperature Regime and Geoelectric Smentioning

confidence: 99%

“…1, 2). This profile runs through the entire breadth of the northern block of SGT In this region, crust has been interpreted as consisting of four Data Source: Gupta et al (1987Gupta et al ( , 1991; Roy and Rao (2000); Gupta and Rao (1970);Rao et al (1976Rao et al ( , 2001; Ray et al (2000).…”

Section: Crustal Velocity Structurementioning

confidence: 99%

See 2 more Smart Citations

Unusual lithospheric structure and evolutionary pattern of the cratonic segments of the South Indian shield

Agrawal

Pandey

2014

Earth Planet Sp

View full text Add to dashboard Cite

The southern Indian shield, characterised by several prominent geological and geophysical features, can be divided into three distinct tectonic segments: Western Dharwar craton (WDC), Eastern Dharwar craton (EDC) and Southern Granulite terrain (SGT). With the exception of WDC, the entire crust beneath EDC and SGT has been remobilized several times since their formation during the mid-to late Archeans (3.0-2.5 Ga). In order to understand the evolutionary history of these segments, a multiparametric geological and geophysical study has been made which indicates that the south Indian shield, characterized by a reduced heat flow of 23-38 mW/m 2 has a much thinner (88-163 km) lithosphere compared to ∼200-450 km found in other global shields. In the EDC-SGT terrain, high velocity upper crust is underlain by considerably low mantle velocity with a thick high conductive/low velocity zone sandwiched at mid crustal level. Our study reveals that the entire EDC region is underlain by granulite facies rocks with a density of about 2.85 to 3.16 g/cm 3 at a shallow depth of about 8 km in the southern part and at even shallower depth of about 1 to 2 km below the Hyderabad granitic region in the north. Cratonic mantle lithosphere beneath EDC may contain a highly conductive, anisotropic and hydrous metasomatic zone between the depth of 90 and 105 km where estimated temperatures are in the range of 850-975• C. It is likely that before the early Proterozoic, the entire south Indian shield was a coherent crustal block which subsequently got segmented due to persistent plume-induced episodic thermal reactivations during the last 2.7 Ga. These reactivations led to self destruction of cratonic roots giving rise to negative buoyancy at deeper levels which may have been responsible for crustal remobilisations, followed by regional uplifting and erosion of once substantially thick greenstone belts. Consequently, the crustal column beneath the EDC has become highly evolved and now corresponds closely to SGT at depth.

show abstract

Section: Heat Flow Distribution Temperature Regime and Geoelectric Smentioning

confidence: 99%

Section: Heat Flow Distribution Temperature Regime and Geoelectric Smentioning

confidence: 99%

See 1 more Smart Citation

Unusual lithospheric structure and evolutionary pattern of the cratonic segments of the South Indian shield

Agrawal

Pandey

2014

Earth Planet Sp

View full text Add to dashboard Cite

show abstract

“…Seismic tomography data suggest that the West Australian Archean lithosphere is 200-300 km thick [Simons et al, 1999] and thermal modeling implies a depth of 170-230 km for the 1300°C isotherm [Artemieva and Mooney, 2001]. Assuming ∆z L = 200-250 km, ∆T L = 1280-1300°C, and uniform thermal conductivity k = 3 W m −1°C−1 for the lithosphere, equation (8) Jones, 1988;Gupta et al, 1991;Jaupart and Mareschal, 1999;Russell et al, 2001]. In fact, q m must be lower than this, perhaps by as much as 5 mW m −2 , because of the contribution of heat production in the crust [e.g., Jaupart and Mareschal, 2003].…”

Section: Archean Q Cmentioning

confidence: 99%

Thermal and mechanical controls on the evolution of archean crustal deformation: Examples from Western Australia

Bodorkos

Sandiford

2006

Archean Geodynamics and Environments

View full text Add to dashboard Cite

Dome-and-keel formation in Archean granite-greenstone terrains was uniquely favored by high abundances of heat-producing elements (HPEs) in the crust, and the ubiquity of pre-doming "greenstone-over-granite" stratification, which constituted large-scale density inversions and facilitated long-term steepening of the geotherm via burial of felsic basement-hosted HPEs. This contribution investigates the influence of these factors on the thermo-mechanical stability of the crust, with reference to two contrasting Archean granite-greenstone terrains in Western Australia. In the Neoarchean Eastern Goldfields Province, the rapid (2715-2665 Ma) accumulation of a thin (8-km) greenstone succession atop HPEpoor felsic crust (radiogenic heat flow contribution q c = 45 mW m −2 ) raised midcrustal temperatures from 230°C to 370°C prior to 2650 Ma dome-and-keel formation. In such cold, strong crust, the development of broad, granite-cored antiforms and narrow, greenstone-cored synforms with little strike variation is likely to directly reflect far-field, horizontal tectonic forces, oriented perpendicular to the regional structural grain. In contrast, the Mesoarchean East Pilbara Granite-Greenstone Terrane underwent slow (3515-3325 Ma) accumulation of tick (14-km) greenstones atop HPE-rich (q c = 70 mW m −2 ) basement, which raised mid-lower crustal temperatures from 400°C to 750-800°C, prior to 3300 Ma dome-and-keel formation. The effective viscosity of this hot, weak crust was further reduced by partial melting of the felsic basement; the resulting "classical" architecture (featuring granite domes flanked by greenstone keels with a variety of strike orientations) may therefore reflect partial convective overturn and vertical reorganization of the crust during thermo-mechanical stabilization.

show abstract

“…In summary, there are various lithospheric thicknesses, apparently in a stable equilibrium, coexisting over the convecting Earth's mantle: Secondary convection seems to bring a heat flow of the order of 40 mW/m 2 to the base of thin lithospheres; a mantle heat flow of only 15 mW/m 2 arrives at the base of the thick cratonic roots [Jones, 1988;Gupta et al, 1991;Pinet and Jaupart, 1987]. The petrological buoyancy of the cratonic lithosphere is often invoked to explain its great thickness and stability [Jordan, 1988] .…”

Section: Introductionmentioning

confidence: 99%

Mantle convection and stability of depleted and undepleted continental lithosphere

Doin¹,

Fleitout²,

Christensen³

1997

J. Geophys. Res.

188

145

View full text Add to dashboard Cite

Abstract.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 I and 2). The equilibrium thickness of the oceanic lithosphere (around 100 km) implies that the viscosity in the asthenosphere is less than 7x10 •s Pa s. Only models with strongly pressure-dependent viscosity laws (activation volumes greater than 9x10 -6 ma/mol) are able to reconcile this value with the average upper mantle viscosity (5 x 10 •'ø 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.

show abstract

Heat flow and heat generation in the Archaean Dharwar cratons and implications for the Southern Indian Shield geotherm and lithospheric thickness

Cited by 106 publications

References 43 publications

Unusual lithospheric structure and evolutionary pattern of the cratonic segments of the South Indian shield

Unusual lithospheric structure and evolutionary pattern of the cratonic segments of the South Indian shield

Thermal and mechanical controls on the evolution of archean crustal deformation: Examples from Western Australia

Mantle convection and stability of depleted and undepleted continental lithosphere

Contact Info

Product

Resources

About