Zircon U–Pb (SHRIMP) Ages of the Jahazpur Granite and Mangalwar Gneiss from the Deoli-Jahazpur Sector, Rajasthan, NW India: A Preliminary Reappraisal of Stratigraphic Correlation and Implications to Crustal Growth
“…The Aravalli Craton of the northwestern Indian Shield exposes a well‐preserved Archaean basement in its central and southern parts, known as the Banded Gneissic Complex (BGC, Gupta, 1934; Heron, 1953). This basement has been affected by repeated deformation, metamorphism, and granitic magmatism for much of its geological history (e.g., Ahmad, Mondal, Bhutani, & Satyanarayanan, 2018; Ahmad, Mondal, & Satyanarayanan, 2019; Bhowmik, Bernhardt, & Dasgupta, 2010; Buick et al, 2010; D'Souza et al, 2019; Dey et al, 2019; Fareeduddin & Banerjee, 2020; Gopalan, Macdougall, Roy, & Murali, 1990; Kaur et al, 2019; Rahaman, Mondal, Ahmad, Bhutani, & Choudhary, 2019; Roy & Kröner, 1996; Roy, Kröner, Rathore, Laul, & Purohit, 2012; Wiedenbeck et al, 1996).…”
Section: Introductionmentioning
confidence: 99%
“…Yellow stars with corresponding crystallization ages (inset) mark major Neoarchaean granitoids in the Aravalli Craton. The age for the Jahazpur granite (i) is from Dey et al (2019). Ages for the Berach (ii) and Untala (iii) granites are from Wiedenbeck, Goswami, and Roy (1996) and Kaur, Zeh, and Chaudhri (2019).…”
Section: Introductionmentioning
confidence: 99%
“…The BGC includes many Neoarchaean granitoids, ranging in size from dykes and stocks to batholiths, and in composition from TTGs and sanukitoids to potassic granites (e.g., Dey et al, 2019; Kaur et al, 2019; Mondal & Raza, 2013; Rahaman et al, 2019; Wiedenbeck et al, 1996; Figure 1b). D'Souza et al (2019) identified a granite pluton, the Malola granite, forming the basement for the ca.…”
The Banded Gneissic Complex of the Aravalli Craton of northwestern India comprises Palaeo‐ to Neoarchaean (3.3–2.7 Ga) gneisses, including tonalite–trondhjemite–granodiorite (TTG) gneisses, intruded by Neoarchaean (2.6–2.5 Ga) TTGs, sanukitoids, and potassic granites. The latter include the Malola granite that crops out near Bhilwara and forms the basement for the Mesoproterozoic Pur‐Banera mineralized belt. The granite has experienced three deformation events, represented by an S1 foliation and superimposed open folds and dextral shears. Textural evidence and thermobarometry indicate that prograde metamorphism initially forming actinolite and subsequently diopside, and culminating in the upper amphibolite facies, was followed by retrograde metamorphism in the greenschist facies with fluid influx, forming zoisite. Zircon geochronology yields a crystallization age of 2,538 ± 11 Ma and indicates a prominent metamorphic overprint in the region at 1,307 ± 9 Ma. The Malola granite has low Sr–Nd isotopic ratios, enrichments in fluid‐mobile elements (Cs, Rb, Ba, Th, and Pb), and depletions in alteration‐resistant elements (Nb, Ta, and Ti). These characteristics combined with mineralogical evidence suggest that the granite was derived by anatexis of older crystalline crust (possibly granulitic lower crust) in the same subduction zone setting inferred previously for other Neoarchean granitoids in this region. Geochemical and Sr–Nd–Hf isotopic similarities between the Malola granite and Neoarchaean granitoids of the Aravalli, Bundelkhand, Bastar, Dharwar, and Congo cratons indicate a major role for anatectic crustal reworking in their genesis.
“…The Aravalli Craton of the northwestern Indian Shield exposes a well‐preserved Archaean basement in its central and southern parts, known as the Banded Gneissic Complex (BGC, Gupta, 1934; Heron, 1953). This basement has been affected by repeated deformation, metamorphism, and granitic magmatism for much of its geological history (e.g., Ahmad, Mondal, Bhutani, & Satyanarayanan, 2018; Ahmad, Mondal, & Satyanarayanan, 2019; Bhowmik, Bernhardt, & Dasgupta, 2010; Buick et al, 2010; D'Souza et al, 2019; Dey et al, 2019; Fareeduddin & Banerjee, 2020; Gopalan, Macdougall, Roy, & Murali, 1990; Kaur et al, 2019; Rahaman, Mondal, Ahmad, Bhutani, & Choudhary, 2019; Roy & Kröner, 1996; Roy, Kröner, Rathore, Laul, & Purohit, 2012; Wiedenbeck et al, 1996).…”
Section: Introductionmentioning
confidence: 99%
“…Yellow stars with corresponding crystallization ages (inset) mark major Neoarchaean granitoids in the Aravalli Craton. The age for the Jahazpur granite (i) is from Dey et al (2019). Ages for the Berach (ii) and Untala (iii) granites are from Wiedenbeck, Goswami, and Roy (1996) and Kaur, Zeh, and Chaudhri (2019).…”
Section: Introductionmentioning
confidence: 99%
“…The BGC includes many Neoarchaean granitoids, ranging in size from dykes and stocks to batholiths, and in composition from TTGs and sanukitoids to potassic granites (e.g., Dey et al, 2019; Kaur et al, 2019; Mondal & Raza, 2013; Rahaman et al, 2019; Wiedenbeck et al, 1996; Figure 1b). D'Souza et al (2019) identified a granite pluton, the Malola granite, forming the basement for the ca.…”
The Banded Gneissic Complex of the Aravalli Craton of northwestern India comprises Palaeo‐ to Neoarchaean (3.3–2.7 Ga) gneisses, including tonalite–trondhjemite–granodiorite (TTG) gneisses, intruded by Neoarchaean (2.6–2.5 Ga) TTGs, sanukitoids, and potassic granites. The latter include the Malola granite that crops out near Bhilwara and forms the basement for the Mesoproterozoic Pur‐Banera mineralized belt. The granite has experienced three deformation events, represented by an S1 foliation and superimposed open folds and dextral shears. Textural evidence and thermobarometry indicate that prograde metamorphism initially forming actinolite and subsequently diopside, and culminating in the upper amphibolite facies, was followed by retrograde metamorphism in the greenschist facies with fluid influx, forming zoisite. Zircon geochronology yields a crystallization age of 2,538 ± 11 Ma and indicates a prominent metamorphic overprint in the region at 1,307 ± 9 Ma. The Malola granite has low Sr–Nd isotopic ratios, enrichments in fluid‐mobile elements (Cs, Rb, Ba, Th, and Pb), and depletions in alteration‐resistant elements (Nb, Ta, and Ti). These characteristics combined with mineralogical evidence suggest that the granite was derived by anatexis of older crystalline crust (possibly granulitic lower crust) in the same subduction zone setting inferred previously for other Neoarchean granitoids in this region. Geochemical and Sr–Nd–Hf isotopic similarities between the Malola granite and Neoarchaean granitoids of the Aravalli, Bundelkhand, Bastar, Dharwar, and Congo cratons indicate a major role for anatectic crustal reworking in their genesis.
“…The NW Indian craton of Rajasthan (also known as Rajasthan craton or Aravalli craton), made up mostly of the Banded Gneissic Complex (BGC), is flanked on the west by the Proterozoic fold belts of the Aravalli and Delhi Supergroup rocks (Heron, 1953) that has attracted the attention of scientists because of its heterogeneous lithological assemblages, tectonic stacking, and early Archaean to mid Proterozoic complex magmatic-metamorphic history. The BGC has been reclassified as the Bhilwara Supergroup (BSG, Raja Rao, 1970;Gupta et al, 1997) which is made up of lithologies of granulite facies Sandmata Complex (SC, 2.29−1.72 Ga; Sarkar et al, 1989;Buick et al, 2006), amphibolite facies Mangalwar Complex (MC, 3.3−2.8 Ga; Gopalan et al, 1990) and greenschist facies Hindoli Group (younger than 2.52 Ga; Dey et al, 2018). The geology of the BSG has been worked out in detail by Guha and Bhattacharya (1995), Mohanty and Guha (1995), Gupta et al (1997), Chakrabarti et al (2004), Guha (2018), and specially the geological and petrological details of the migmatite gneisses and its enclosing granite pluton (Anjana Granite) north of the present granite pluton (Amet Granite) is dealt in detail by Guha et al (2018).…”
Allanite and REE bearing minerals are primum fama report from migmatite gneisses, plutonic Amet granite and intrusive alkaline rocks of Rajasthan, and these minerals are important for establishing REE deposit. Allanite taken from host migmatite and granite have been analysed along with host rocks containing REE minerals, both of which contain appreciably high amount of ΣREE and Th. Allanite phases identified are CaO and Ce 2 O 3 rich with positive correlation of silica and alumina. As silica proportion decreases and ΣREE increases, allanite changes to britholite and thorite indicating a role of fluid in its crystallization. The chondrite normalized REE in migmatite gneiss and allanite mineral is compatible indicating a primary nature of allanite. The carrier of REE minerals is envisaged as the alkaline intrusives which deposited their REE minerals during ascent of magma from deeper source. Chemico-mineralogical study of Allanite and its hosts suggest possible reaction between a REE bearing fluid rich in P and F brought up by alkaline rocks, and the silicate minerals, mainly biotite and hornblende of the migmatite gneiss and Amet granite. The allanite in migmatite gneiss and granite may prove to be a sumptuous deposit of REE minerals in India, and similar terrains elsewhere.
“…In the Jahajpur area two parallel ridges of dolomitic limestone occur from Ghevaria (SW) up to Jahajpur (NW) [6, 7]. Figure 1Geology map of the study area [17, 18, 19]…”
Advancement of airborne hyperspectral remote sensing techniques provides subtle variations to identify minerals and to make distinctions between rock formations. These techniques clearly define barren land versus economically viable zones containing ores and minerals. As we know profitable mineral zones are commonly associated with hydrothermal alteration zones, hyperspectral remote sensing techniques have the capability to identify and distinguish between altered, weathered, and clay minerals. In this research work, airborne hyperspectral remote sensing image from AVIRIS-NG is used to identify hydrothermally altered minerals in the Jahajpur region of Bhilwara district, Rajasthan, India. The purpose of this study is the identification of the minerals through spectral features of image spectra in corroboration with field sample spectra and USGS laboratory spectra. The spectral angle mapper (SAM) and Spectral Feature Fitting (SFF) algorithms were used for the mapping of the minerals. This study was conducted to prove the capability of AVIRIS-NG hyperspectral remote sensing data to identify zones of profitable mineral deposits.
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