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

<p>The elastic thickness (Te) of continents is a matter of much debate. Recent studies have shown that a number of factors control the continental Te, including age, heat flow, and lithospheric thickness. Here, we estimate the Te structure of the whole Indian shield using an improved isotropic fan wavelet land ocean deconvolution methodology, and we compare these results with the global published Te estimates in the Archean, Proterozoic and younger geological provinces. Our study reveals low (0-45 km/0-35 km), intermediate (45-70 km) and high (70-100 km) Te values in the Archean/Quaternary, the Proterozoic, and the Tertiary provinces, respectively, of the Indian shield. This is in contrast with global estimates of Te in similar geological provinces. In the absence of any correlation of Te with any controlling parameters, we propose that the mantle properties, rather than the tectonic history, are responsible for influences on the Te values within the Indian shield. The global positioning system horizontal velocity vectors yielded a locking depth of ca. 20 ±4 km, and the aseismic creep beyond correlates well with the high strength of ca. 70 km to 100 km in the central Himalayan foreland.</p>

Download Full-text

Radioactive heat generation and heat flow in the Indian shield

Earth and Planetary Science Letters ◽

10.1016/0012-821x(76)90008-x ◽

1976 ◽

Vol 30 (1) ◽

pp. 57-64 ◽

Cited By ~ 111

Author(s):

R.U.M. Rao ◽

G.V. Rao ◽

Hari Narain

Keyword(s):

Heat Flow ◽

Heat Generation ◽

Indian Shield

Download Full-text

Thermal regime of the lithosphere in the Canadian ShieldThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.

Canadian Journal of Earth Sciences ◽

10.1139/e09-059 ◽

2010 ◽

Vol 47 (4) ◽

pp. 389-408 ◽

Cited By ~ 17

Author(s):

Claire Perry ◽

Carmen Rosieanu ◽

Jean-Claude Mareschal ◽

Claude Jaupart

Keyword(s):

Heat Flow ◽

Heat Generation ◽

Seismic Refraction ◽

Surface Heat ◽

Canadian Shield ◽

P Wave ◽

Seismic Velocities ◽

Flow Measurements ◽

Surface Heat Flow ◽

Mantle Heat Flow

Geothermal studies were conducted within the framework of Lithoprobe to systematically document variations of heat flow and surface heat production in the major geological provinces of the Canadian Shield. One of the main conclusions is that in the Shield the variations in surface heat flow are dominated by the crustal heat generation. Horizontal variations in mantle heat flow are too small to be resolved by heat flow measurements. Different methods constrain the mantle heat flow to be in the range of 12–18 mW·m–2. Most of the heat flow anomalies (high and low) are due to variations in crustal composition and structure. The vertical distribution of radioelements is characterized by a differentiation index (DI) that measures the ratio of the surface to the average crustal heat generation in a province. Determination of mantle temperatures requires the knowledge of both the surface heat flow and DI. Mantle temperatures increase with an increase in surface heat flow but decrease with an increase in DI. Stabilization of the crust is achieved by crustal differentiation that results in decreasing temperatures in the lower crust. Present mantle temperatures inferred from xenolith studies and variations in mantle seismic P-wave velocity (Pn) from seismic refraction surveys are consistent with geotherms calculated from heat flow. These results emphasize that deep lithospheric temperatures do not always increase with an increase in the surface heat flow. The dense data coverage that has been achieved in the Canadian Shield allows some discrimination between temperature and composition effects on seismic velocities in the lithospheric mantle.

Download Full-text

Present-day geothermal regime of the Uliastai Depression, Erlian Basin, North China

Energy Exploration & Exploitation ◽

10.1177/0144598718785970 ◽

2018 ◽

Vol 37 (2) ◽

pp. 770-786 ◽

Cited By ~ 3

Author(s):

Wei Xu ◽

Shaopeng Huang ◽

Jiong Zhang ◽

Ruyang Yu ◽

Yinhui Zuo ◽

...

Keyword(s):

Thermal Conductivity ◽

Heat Flow ◽

Thermal Structure ◽

Rheological Characteristic ◽

Rheological Parameter ◽

Lithospheric Thickness ◽

Terrestrial Heat Flow ◽

Geothermal Regime ◽

Mantle Heat Flow ◽

Erlian Basin

In this study, we calculated the present-day terrestrial heat flow of the Uliastai Depression in Erlian Basin by using systematical steady-state temperature data obtained from four deep boreholes and 89 thermal conductivity measurements from 22 boreholes. Then, we calculated the lithospheric thermal structure, thermal lithospheric thickness, and lithospheric thermo-rheological structure by combining crustal structure, thermal conductivity, heat production, and rheological parameter data. Research from the Depression shows that the present-day terrestrial heat flow ( qs) is 86.3 ± 2.3 mW/m2, higher than the average of 60.4 ± 12.3 mW/m2 of the continental area of China. Mantle heat flow ( qm) in the Depression ranges from 33.7 to 39.3 mW/m2, qm/ qs ranges from 40 to 44%, show that the crust plays the dominant position in the terrestrial heat flow. The thermal thickness of the lithosphere is about 74–88 km and characterized by a “strong crust–weak mantle” rheological characteristic. The total lithospheric strength is 1.5 × 1012 N/m under wet mantle conditions. Present-day geothermal regime indicates that the Uliastai Depression has a high thermal background, the activity of the deep-seated lithosphere is relatively intense. This result differs significantly from the earlier understanding that the area belongs to a cold basin. However, a hot basin should be better consistent with the evidences from lithochemistry and geophysical observations. The results also show the melts/fluids in the study area may be related to the subduction of the Paleo-Asian Ocean. The study of the geothermal regime in the Uliastai Depression provides new geothermal evidence for the volcanic activity in the eastern part of the Central Asian Orogenic Belt and has significant implications for the geodynamic characteristics.

Download Full-text