Heat flow, heat production, and crustal temperatures in the Archaean Bundelkhand craton, north‐central India: Implications for thermal regime beneath the Indian shield

Abstract

Heat flow and heat production data sets constrain the crustal thermal structure in the 2.5–3.5 Ga Bundelkhand craton, the oldest cratonic core in northern Indian shield, for the first time and allow comparisons with the southern Indian shield. Temperature measurements carried out in 10 boreholes at five sites in the craton, combined with systematic thermal conductivity measurements on major rock types, yield low heat flow in the range of 32–41 mW m−2, which is distinct from the generally high heat flow reported from other parts of the northern Indian shield. Radioelemental measurements on 243 samples of drill cores and outcrops reveal both large variability and high average heat production for the Neo‐Archaean to Palaeo‐Proterozoic granites (4.0 ± 2.1 (SD) μW m−3) relative to the Meso‐Archaean tonalite‐trondhjemite‐granodiorite (TTG) gneisses (2.0 ± 1.0 (SD) μW m−3). On the basis of new heat flow and heat production data sets combined with available geological and geophysical information, a set of steady state, heat flow‐crustal heat production models representative of varying crustal scenarios in the craton are envisaged. Mantle heat flow and Moho temperatures are found to be in the range of 12–22 mW m−2 and 290–420°C, respectively, not much different from those reported for the similar age Dharwar craton in southern India. This study reveals similar mantle thermal regimes across the northern and southern parts of the Indian shield, in spite of varying surface heat flow regimes, implying that much of the intraprovince and interprovince variations in the Indian shield are explained by variations in upper crustal heat production.

Thermal and Physical Properties of Deccan Basalt and Neoarchean Basement Cores From a Deep Scientific Borehole in the Koyna−Warna Seismogenic Region, Deccan Volcanic Province, Western India: Implications on Thermal Modeling and Seismogenesis

“…Density of the basement rocks in the present study (range from 2,600 to 2,820 kg m −3 with an average of 2,720 kg m −3 ) is significantly lower than the basement rocks of the Killari borehole (range from 2,690 to 3,060 kg m −3 , with an average of 2,819 kg m −3 ) (Tripathi et al., 2012), but slightly higher than the range that is observed for the granitic rocks of the Dharwar Craton (2,520–2,730 kg m −3 with an average of 2,640 kg m −3 ) (Vijaya Raghava et al., 1977), as well as upper crustal granitic/gneissic rocks from different regions of the Indian shield (Chopra et al., 2018, 2020; Podugu et al., 2017; Ray et al., 2003). These studies yielded two important points: (a) the subsurface basement density is not the same in different parts of the DVP, which as corroborates the results of Tiwari et al.…”

Reconciling Geophysical and Petrological Estimates of the Thermal Structure of Southern Tibet

“…In our preferred model of the initial steady‐state Indian thermal structure (shown in Figure 4), based on crustal data from the cratonic western Dharwar province (Roy & Mareschal, 2011), we use a 19‐km upper crust of tonalite‐trondhjemite‐granodiorite gneiss, overlying a 19‐km lower crust of mafic granulite, with radiogenic heat production of 1.1 and 0.36 μW m −3 , respectively, yielding a surface heat flux of 41.0 mW m −2 . Given the paucity of comprehensive data on crustal structure and heat production, we also trial three further models (Figure 4) for crustal heat production, based on values for the eastern Dharwar (Roy & Mareschal, 2011) and Bundelkhand (Podugu et al., 2017) provinces, all summarized in Table S1. Figure 5 then shows a comparison between our preferred model (western Dharwar) and the other three models.…”

“…The third row shows a model using a modified set of values for eastern Dharwar with a less‐depleted lower crust. The fourth row shows a model using the heat production values from the Bundelkhand craton in northern India (Podugu et al., 2017).…”

Bundelkhand Craton

“…The Dhala impact structure, Shivpuri district, M.P., India since its confirmation as a bona fide terrestrial meteoritic impact structure based on the observation of diagnostic evidences of shock metamorphism (Pati, 2005;Pati et al, 2008;Pati et al, 2019) continues to attract the attention of geoscientific community. Gaur et al (2016) considered the impact melt breccia as "felsic volcanics" and further suggested that this "acid volcanic activity" is correlated to a global event at 1 Ga. Roy et al (2017) reported subsurface data from 14 boreholes out of 70 locations drilled (up to a depth of 476.55 m) in different parts of Dhala structure in search of uranium and the laudable extensive drilling activity by the Atomic Minerals Directorate for Exploration and Research, Govt. of India immensely helped in the better understanding of the impact cratering process at Dhala.…”

“…Li et al (2018) studied the impact melt breccia and reported the presence of reidite, a high pressure polymorph of zircon and further constrained the age of Dhala impact between 2.44 and 2.24 Ga, although both findings have been questioned (Pati et al, 2018). Podugu et al (2017) reported heat flow, heat production and crustal temperatures of BuC based on data collected from 10 borehole cores in five locations (one to the north of BTZ and four to the southern part). They observe a low heat flow (32-41 mWm -2 ) unlike AC but similar to Dharwar and other Archean Cratons worldwide.…”